Description:

BACKGROUND

Some vehicles are configured to operate in an autonomous mode in which the vehicle navigates through an environment with little or no input from a driver. Such an autonomous vehicle (or AV) typically includes one or more sensors that are configured to sense information about the environment. The autonomous vehicle may use the sensed information to navigate through the environment. For example, if the sensors determine that the autonomous vehicle is approaching an obstacle, the vehicle may be able to navigate around the obstacle. An autonomous vehicle may operate in various weather and lighting conditions, such as, but not limited to, days, nights, good visibility conditions, and/or reduced visibility conditions.

SUMMARY

In one aspect, a system is provided. The system may include an autonomous vehicle and an assistance center. The autonomous vehicle may include a stuck condition detection component and a communications component. The stuck condition detection component may be configured to detect a condition in which the autonomous vehicle is impeded from navigating according to a first trajectory. The communications component may be configured at least to send an assistance signal indicating that the autonomous vehicle seeks assistance navigating according to the first trajectory, and to receive a response to the assistance signal. The assistance signal may include sensor information of the autonomous vehicle, indicating low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle. The assistance center may include a communications component and a trajectory specification component. The communications component may be configured at least to receive the assistance signal, and to send the response to the assistance signal. The trajectory specification component may be configured to specify a second trajectory for the autonomous vehicle and to generate the response to the assistance signal including a representation of the second trajectory. The second trajectory may be based on the first trajectory. The second trajectory may ignore the presence of at least part of one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory.

In another aspect, a method is provided. An autonomous vehicle may detect a condition in which the autonomous vehicle is impeded from navigating according to a first trajectory. The autonomous vehicle may send, to an assistance center, an assistance signal that the autonomous vehicle seeks assistance navigating according to the first trajectory. The assistance signal may include sensor information of the autonomous vehicle indicating low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle. The autonomous vehicle may receive a response to the assistance signal. The response may include a representation of a second trajectory, where the second trajectory is based on the first trajectory. The second trajectory may ignore the presence of at least part of one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory.

In another aspect, an autonomous vehicle is provided. The autonomous vehicle may include one or more processors and a non-transitory computer readable medium storing instructions that, when executed by the one or more processors, cause the autonomous vehicle to perform functions. The functions may include detecting a condition in which the autonomous vehicle is impeded from navigating according to a first trajectory. The functions may also include sending an assistance signal, from the autonomous vehicle to an assistance center, that the autonomous vehicle seeks assistance navigating according to the first trajectory. The assistance signal may include sensor information of the autonomous vehicle indicating low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle. The functions may also include receiving a response to the assistance signal. The response may include a representation of a second trajectory that could be based on the first trajectory. The second trajectory may ignore the presence of at least part of one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory.

In another aspect, a device is provided. The device may include means for detecting a condition in which navigation according to a first trajectory is impeded, and means for sending an assistance signal to an assistance center seeking assistance to navigate according to the first trajectory. The assistance signal may include sensor information indicating low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the device. The device may also include means for receiving a response to the assistance signal from the assistance center. The response may include a representation of a second trajectory, where the second trajectory may be based on the first trajectory, and where the second trajectory may ignore the presence of at least part of one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory.

In another aspect, a method is provided. It may be determined that a speed of an autonomous vehicle is less than or equal to a threshold speed, and that the autonomous vehicle has not detected a traffic control signal. A cause C may be identified for the speed to be less than or equal to the threshold speed. A timer T may be started, where the timer T may be based on the cause C. After the timer T expires, it may be determined whether the cause C remains for the speed to be less than or equal to the threshold speed. After determining that the cause C remains for the speed to be less than or equal to the threshold speed, an assistance signal may be sent by the autonomous vehicle indicating that the autonomous vehicle is stuck.

In another aspect, an autonomous vehicle is provided. The autonomous vehicle may include one or more processors and data storage storing program instructions that, when executed by the one or more processors, cause the autonomous vehicle to perform functions. The functions may include determining that a speed is less than or equal to a threshold speed and that a traffic control signal has not been detected. The functions may also include identifying a cause C for the speed to be less than or equal to the threshold speed, and starting a timer T. The functions may further include, after the timer T expires, determining whether the cause C remains for the speed to be less than or equal to the threshold speed, and, after determining that the cause C remains for the speed to be less than or equal to the threshold speed, sending an assistance signal indicating that that the autonomous vehicle is stuck. The timer T may be based on the cause C.

In another aspect, a non-transitory computer readable medium is provided. The non-transitory computer readable medium may store instructions thereon that, when executed by one or more processors, cause the one or more processors to perform functions. The functions may include determining that a speed is less than or equal to a threshold speed, and that a traffic control signal has not been detected. The functions may also include identifying a cause C for the speed to be less than or equal to the threshold speed, and starting a timer T. The functions may further include, after the timer T expires, determining whether the cause C remains for the speed to be less than or equal to the threshold speed, and, after determining that the cause C remains for the speed to be less than or equal to the threshold speed, sending an assistance signal indicating that an autonomous vehicle is stuck. The timer T may be based on the cause C.

In another aspect, a device is provided. The device may include means for determining that a speed is less than or equal to a threshold speed and that a traffic control signal has not been detected. The device may also include means for identifying a cause C for the speed to be less than or equal to the threshold speed, and means for starting a timer T. The device may further include means for, after the timer T expires, determining whether the cause C remains as a cause for the speed to be less than or equal to the threshold speed, and means for, after determining that the cause C remains the cause for the speed to be less than or equal to the threshold speed, sending an assistance signal indicating that the device is stuck. The timer T may be based on the cause C.

In another aspect, a method is provided. An autonomous vehicle may determine to seek assistance to navigate in accordance with a first trajectory. The autonomous vehicle may be configured to receive and store data about a plurality of obstacles. A particular obstacle in the plurality of obstacles may partially or wholly obstruct the first trajectory. The autonomous vehicle may select a portion of the stored data, where the portion of the stored data is less than the totality of the stored data and includes data representing the particular obstacle. The portion of the stored data may be provided to an assistance center. A second trajectory may be received from the assistance center, where the second trajectory is not obstructed by the particular obstacle.

In another aspect, an autonomous vehicle is provided. The autonomous vehicle include one or more processors and data storage storing program instructions thereon that, when executed by the one or more processors, cause the autonomous vehicle to perform functions. The functions may include determining to seek assistance to navigate in accordance with a first trajectory. The data storage may be configured to receive and store data about a plurality of obstacles, and a particular obstacle in the plurality of obstacles may partially or wholly obstruct the first trajectory. The functions may also include selecting a portion of the stored data. The selected portion of the stored data may be less than the totality of the stored data and may include data representing the particular obstacle. The functions may further include providing, to an assistance center, the portion of the stored data, and receiving, from the assistance center, a second trajectory. The second trajectory might not be obstructed by the particular obstacle.

In another aspect, a non-transitory computer readable medium is provided. The non-transitory computer readable medium may store instructions thereon that, when executed by one or more processors, cause the one or more processors to perform functions. The functions may include determining to seek assistance to navigate an autonomous vehicle in accordance with a first trajectory. The autonomous vehicle may be configured to receive and store data about a plurality of obstacles, and a particular obstacle in the plurality of obstacles may partially or wholly obstruct the first trajectory. The functions may include selecting a portion of the stored data. The selected portion of the stored data may be less than the totality of the stored data and may include data representing the particular obstacle. The functions may further include providing, to an assistance center, the portion of the stored data, and receiving, from the assistance center, a second trajectory. The second trajectory might not be obstructed by the particular obstacle.

In another aspect, a device is provided. The device may include means for determining to seek assistance to navigate an autonomous vehicle in accordance with a first trajectory. The autonomous vehicle may be configured to receive and store data about a plurality of obstacles, and a particular obstacle in the plurality of obstacles may partially or wholly obstruct the first trajectory. The device may also include means for selecting a portion of the stored data. The selected portion of the stored data may be less than the totality of the stored data and may include data representing the particular obstacle. The device may further include means for providing, to an assistance center, the portion of the stored data, and means for receiving, from the assistance center, a second trajectory. The second trajectory might not be obstructed by the particular obstacle.

In another aspect, a method is provided. An assistance center may receive a representation of a first trajectory of an autonomous vehicle that is in a stuck condition, where the first trajectory does not relieve the stuck condition. The assistance center may receive sensor information of the autonomous vehicle, where the sensor information may include low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle. The high-level, polygonal or polyhedral representations of objects may be based, at least in part, on the low-level sensor strike input. Based on the first trajectory and the sensor information, the assistance center may determine a second trajectory that relieves the stuck condition while adhering to at least some navigational constraints.

Relieving the stuck condition may include ignoring at least one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory. The assistance center may transmit a representation of the second trajectory and instructions for the autonomous vehicle to drive in accordance with the second trajectory.

In another aspect, a non-transitory computer readable medium is provided. The non-transitory computer readable medium may store instructions thereon that, when executed by a computing device, cause the computing device to perform functions. The functions may include receiving a representation of a first trajectory of an autonomous vehicle that is in a stuck condition. The first trajectory might not relieve the stuck condition. The functions may also include receiving sensor information of the autonomous vehicle, where the sensor information may include low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle. The high-level, polygonal or polyhedral representations of objects may be based, at least in part, on the low-level sensor strike input. The functions may further include, based on the first trajectory and the sensor information, determining a second trajectory that may relieve the stuck condition while adhering to at least some navigational constraints. Relieving the stuck condition may include ignoring at least one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory. The functions may additionally include transmitting a representation of the second trajectory and instructions for the autonomous vehicle to drive in accordance with the second trajectory.

In another aspect, a device is provided. The device may include means for receiving a representation of a first trajectory of an autonomous vehicle that is in a stuck condition. The first trajectory might not relieve the stuck condition. The device may also include means for receiving sensor information of the autonomous vehicle, where the sensor information may include low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle. The high-level, polygonal or polyhedral representations of objects may be based, at least in part, on the low-level sensor strike input. The device may also include means for determining a second trajectory, based on the first trajectory and the sensor information, which relieves the stuck condition while adhering to at least some navigational constraints. Relieving the stuck condition may include ignoring at least one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory. The device may additionally include means for transmitting a representation of the second trajectory and instructions for the autonomous vehicle to drive in accordance with the second trajectory.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, appearances, embodiments, and features described above, further aspects, appearances, embodiments, and features will become apparent by reference to the figures and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of an example method, according to an example embodiment.

FIG. 2 is a flow chart of another example method, according to an example embodiment.

FIG. 3 is a flow chart of yet another example method, according to an example embodiment.

FIG. 4 is a flow chart of still another example method, according to an example embodiment.

FIG. 5 shows an example autonomous vehicle operating environment, according to an example embodiment.

FIG. 6 shows a scenario where an autonomous vehicle is in a stuck condition, according to an example embodiment.

FIG. 7 is a flow chart of an example method for detecting whether an autonomous vehicle is in a stuck condition, according to an example embodiment.

FIG. 8 shows an example scenario where an autonomous vehicle is attempting to follow an original trajectory to destination, according to an example embodiment

FIG. 9 shows another example scenario where an autonomous vehicle is attempting to follow an original trajectory to destination, according to an example embodiment.

FIG. 10 is a flow chart of an example method where an autonomous vehicle requests assistance from an assistance center to relieve a stuck condition, according to an example embodiment.

FIG. 11 schematically illustrates a LIDAR unit scanning across an obstacle-filled environmental scene, according to an example embodiment.

FIG. 12 schematically illustrates an example point cloud corresponding to the obstacle-filled environmental scene of FIG. 11.

FIG. 13 schematically illustrates spatial point data indicative of a surface of a target vehicle that is stationary relative to a LIDAR unit, according to an example embodiment.

FIG. 14 schematically illustrates spatial point data indicative of a surface of a target vehicle that is moving relative to a LIDAR unit, according to an example embodiment.

FIGS. 15A, 15B, and 15C show a scenario for using a trajectory interface to relieve a stuck condition of an autonomous vehicle, according to example embodiments.

FIG. 16 is a functional block diagram illustrating an autonomous vehicle, according to an example embodiment.

FIG. 17 is a functional block diagram illustrating an assistance center, according to an example embodiment.

FIG. 18 shows a vehicle that may be similar or identical to the vehicle described with respect to FIG. 16, according to an example embodiment.

FIG. 19A is a block diagram of a computing device, according to an example embodiment.

FIG. 19B depicts a network of computing clusters arranged as a server system, according to an example embodiment.

DETAILED DESCRIPTION

Autonomous vehicles may navigate by using a number of sensors to collect information about objects in the vicinity of the autonomous vehicle, and by determining trajectories for the autonomous vehicle based on this collected information. For instance, an autonomous vehicle may be equipped with one or more video cameras, still cameras, radar units, Light Detection and Ranging (LIDAR) units, Global Positioning System (GPS) units, and/or perhaps other types of location-determining or object-detection technologies.

For instance, the autonomous vehicle may be configured with a LIDAR unit to generate the low-level data about nearby environmental features. The LIDAR unit may estimate distances to these environmental features while scanning through the surroundings of the autonomous vehicle. Thus, the LIDAR unit may assemble a cloud of point positions indicative of the three-dimensional shapes of objects in the surroundings. Individual points may be measured by generating a laser pulse and detecting a returning pulse, if any, reflected from an environmental object, and determining the distance to the reflective object according to the time delay between the emitted pulse and the reception of the reflected pulse.

The laser, or set of lasers, may be rapidly and repeatedly scanned across the surroundings to provide continuous, or nearly continuous, real-time information on distances to the objects therein. Combining the measured distances, and the orientation of the laser(s) while measuring each distance, allows for associating a three-dimensional position with each returning pulse. In this way, a three-dimensional map of points of reflective features can be generated based on the returning pulses for the entire scanning zone. Using the three-dimensional point map, high-level data defining the relative sizes, shapes, velocities, and trajectories of various objects (such as other vehicles, pedestrians, trees, structures, etc.) can be inferred. These objects may be represented as polygons or polyhedrons, or by other two-dimensional or three-dimensional representations.

From this information, as well as possible navigational requests from one or more users or controllers of the autonomous vehicle, the autonomous vehicle may develop a trajectory that it can drive from a starting point (e.g., the autonomous vehicle's current location) to an endpoint (e.g., a destination). The trajectory may also specify some number of intermediate waypoints through which the autonomous vehicle should pass while navigating from the starting point to the endpoint.

While driving in accordance with such a trajectory, the autonomous vehicle may adhere to navigational constraints. For instance, the autonomous vehicle may take steps to avoid collisions, to avoid breaking traffic laws (e.g., staying in the proper lane, obeying the speed limit, and stopping fully at stop signs), and to avoid causing inertial discomfort to passengers (e.g., rapid acceleration or deceleration, sudden turns, and so on) unless absolutely necessary. The autonomous vehicle may make use of low-level and high-level sensor information in order to adhere to these constraints. Thus, for example, if the autonomous vehicle detects an obstacle in its trajectory, it may make modifications to the trajectory in order to avoid the obstacle.

In some scenarios, an autonomous vehicle may enter into a “stuck” condition. The stuck condition may be, for instance, a condition where the autonomous vehicle might not be able to navigate in accordance with an original trajectory without relaxing any of its navigational constraints. For example, an autonomous vehicle may be configured with constraint(s) to “stay on the road” and “do not back up while on the road.” Then, while driving, the autonomous vehicle may determine that the road ahead is completely obstructed by a large object. Even if a shoulder of the road and/or the road behind the autonomous vehicle is clear, the autonomous vehicle may not be able to navigate around or away from the large object. Thus, the autonomous vehicle may determine that it is in a stuck condition.

Detecting when the autonomous vehicle is stuck may be a complex problem. Some approaches may generate an excessive number of false positive results. This may lead to over-allocation of resources to assist stuck autonomous vehicles. Other approaches lead to excessive amount of waiting until the autonomous vehicle determines that it is in a stuck condition.

As an example, consider a heuristic of setting a timer whenever the autonomous vehicle stops, and alerting when the stoppage lasts longer than a threshold N seconds. If the threshold N is set to 5 seconds, alerts may be sent while waiting for stop lights, when the autonomous vehicle is in stop and go freeway traffic, and when the autonomous vehicle is navigating stop signs at busy intersections. These alerts are likely to be considered false positives. On the other hand, if N is set to 600 seconds (10 minutes), the autonomous vehicle may wait behind a double parked car on an otherwise empty street for at least 10 minutes. In this situation, the waiting may result in a poor user experience.

Upon determining that the autonomous vehicle is in a stuck condition, the autonomous vehicle may send an assistance request to an assistance center to request assistance. This assistance request may include the location of the autonomous vehicle, as well as some basic data from one or more of the autonomous vehicle's sensors. In response, the assistance center may either accept or reject the assistance request. If the request is accepted, the assistance center may send a new trajectory for use by the autonomous vehicle.

In some cases, in order to provide the navigational assistance, the assistance center may determine that it would benefit from additional data from the autonomous vehicle. The additional data may include data that is too expensive or burdensome for the autonomous vehicle to transmit to the assistance center by default. Low-level data, such as clusters of laser strikes on surfaces in the vicinity of the autonomous vehicle, may be useful to the assistance center. For example, the laser strike data is generally more accurate than high-level object data that may be, at least partially, inferred from the laser strike data.

The low-level data may be useful to an expert in the assistance center, such as a human expert and/or an expert system. However, the autonomous vehicle may generate a large enough volume of low-level data to be impractical for the autonomous vehicle to regularly transmit. Instead, the autonomous vehicle may use heuristics to reduce the extent of transmitted data, such as but not limited to restricting the number of obstacles or objects to report based on proximity to the autonomous vehicle, sorting objects based on the autonomous vehicle's trajectory or location or perceived importance of the objects, and/or preferring expert-friendly types of data for transmission. Additionally, or alternatively, the autonomous vehicle may restrict the data to high-level (e.g., polygonal or polyhedral) representations of these objects that were derived from the low-level data.

Being able to determine when an autonomous vehicle is stuck and then when to request assistance may significantly reduce the extent of experts used to operate a fleet of autonomous vehicles. Such an expert, for instance as a human or an expert system, may be at an assistance center waiting for assistance requests. As such, one expert at an assistance center may assist multiple autonomous vehicles. Thus, if stuck conditions can be efficiently and effectively detected, experts may be freed up for other tasks and the operating costs of autonomous vehicles may be reduced.

Turning to the figures, FIG. 1 is a flow chart of method 100, according to an example embodiment. Method 100 may be carried out by an autonomous vehicle, such as described below in the context of at least FIGS. 16 and 18.

At block 110, an autonomous vehicle may detect a condition in which the autonomous vehicle is impeded from navigating according to a first trajectory, such as discussed below in the context of at least FIGS. 6 and 7.

At block 120, the autonomous vehicle may send an assistance signal to an assistance center, such as discussed below in the context of at least FIGS. 8-10 and 15A-15C. The assistance signal may indicate that the autonomous vehicle seeks assistance navigating according to the first trajectory. The assistance signal may include sensor information of the autonomous vehicle. The sensor information may indicate low-level sensor strike input, such as laser strike input discussed below in the context of FIGS. 11-14, and/or high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle, such as discussed previously, as well as below in the context of FIGS. 11-15C.

At block 130, the autonomous vehicle may receive a response to the assistance signal, such as discussed below in the context of at least FIGS. 8-10 and 15A-15C. The response may include a representation of a second trajectory, where the second trajectory may be based on the first trajectory. The second trajectory may ignore the presence of at least part of one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory, such as discussed below at least in the context of FIGS. 5, 8-10, 15A-15C, and 17. For example, an expert at the assistance center may have determined that the object does not fully obstruct the first trajectory, and therefore may be at least partially ignored.

In some embodiments, the second trajectory may include a path defined by a plurality of points. The path defined by the plurality of points may include a spline connecting at least two points in the plurality of points.

Method 100 may include determining the second trajectory using an expert entity at the assistance center. The second trajectory may be determined based on the assistance signal and the sensor information. In some embodiments, the expert entity may include a human expert. In other embodiments, the expert entity may include a computing system.

In further embodiments, method 100 may include the autonomous vehicle obtaining the second trajectory from the response, and driving according to the second trajectory. Driving the autonomous vehicle according to the second trajectory may include driving according to the first trajectory after driving according to the second trajectory. For instance, the second trajectory may avoid one or more obstacles, and then may lead back to the first trajectory. In some cases, the autonomous vehicle may validate the second trajectory prior to driving according to the second trajectory.

FIG. 2 is a flow chart of method 200, according to an example embodiment. Method 200 may be carried out by an autonomous vehicle, such as described below in the context of at least FIGS. 16 and 18.

At block 210, a determination may be made that a speed of an autonomous vehicle is less than or equal to a threshold speed and that the autonomous vehicle has not detected a traffic control signal, such as discussed below in more detail in the context of at least FIGS. 6 and 7. In some embodiments, determining that the speed of the autonomous vehicle is less than or equal to the threshold speed may include determining that the autonomous vehicle is not increasing speed. The traffic control signal may include be a stop sign signal, a stop light signal, a warning sign signal, and a warning light signal. The threshold speed may be between zero and one meter per second, between zero and three meters per second, between zero and five meters per second, and so on.

At block 220, a cause C may be identified for the speed to be less than or equal to the threshold speed, such as discussed below in more detail in the context of at least FIG. 7. In some embodiments, the cause C may be based on a pedestrian, based on a vehicle other than the autonomous vehicle, and/or based on another type of object. The cause C may obstruct a trajectory of the autonomous vehicle.

At block 230, a timer T that is based on the cause C may be started, such as discussed below in more detail in the context of at least FIG. 7. At block 240, after the timer T expires, a determination may be made whether the speed is still less than or equal to the threshold speed and/or the cause C remains as a cause for the speed to be less than or equal to the threshold speed, such as discussed below in more detail in the context of at least FIG. 7. If this is the case, then, at block 250, an assistance signal indicating that the autonomous vehicle is stuck may be sent from the autonomous vehicle, such as discussed below in more detail in the context of at least FIG. 7.

In some embodiments, method 200 may further include, after sending the assistance signal, determining that the speed of the autonomous vehicle is greater than the threshold speed. Then, based on determining that the speed of the autonomous vehicle is greater than the threshold speed, a determination may be made that the autonomous vehicle is no longer stuck. In this case, the autonomous vehicle may no longer seek out assistance, and may transmit a message to the assistance center indicating that the request for assistance is cancelled.

Method 200 may also include the autonomous vehicle receiving a response to the assistance signal, where the response specifies a second trajectory for the autonomous vehicle, and navigating according to the second trajectory. The second trajectory may avoid the obstruction of cause C. In particular embodiments, method 200 may further include, after navigating according to the second trajectory, determining that the autonomous vehicle may safely return to navigating according to the trajectory. In response to determining that the autonomous vehicle may return to navigating according to the trajectory, the autonomous vehicle may switch from navigating according to the second trajectory to navigating according to the trajectory.

FIG. 3 is a flow chart of method 300, according to an example embodiment.

Method 300 may be carried out by an autonomous vehicle, such as described below in the context of at least FIGS. 16 and 18.

At block 310, the autonomous vehicle may determine to seek assistance to navigate in accordance with a first trajectory. The autonomous vehicle may be configured to receive and store data about a plurality of obstacles. A particular obstacle in the plurality of obstacles may partially or wholly obstruct the first trajectory, such as discussed below in the context of at least FIGS. 5-17. In some embodiments, the stored data may include sensor data about the plurality of obstacles, where the sensor data may comprise representations of distances between the autonomous vehicle and at least some obstacles in the plurality of obstacles, such as discussed below in the context of at least FIGS. 10-15C.

In full generality, one or more particular obstacles may obstruct the first trajectory. For instance, the autonomous vehicle may determine that two, three, or more obstacles are obstructing its trajectory. The autonomous vehcile may take action, in accordance with method 300 and/or any other embodiment herein, to navigate around or otherwise avoid these obstacles. However, for sake of simplicity, some examples herein discuss such processes in the context of a single obstacle.

At block 320, the autonomous vehicle may select a portion of the stored data. The selected portion of the stored data may be less than the totality of the stored data and may include data representing the particular obstacle, such as discussed below in the context of at least FIGS. 10 and 15A-15C. In some embodiments, the stored data may include video data about the plurality of obstacles. Then, selecting the portion of the stored data may include selecting at least some of the video data, such as discussed below in the context of at least FIGS. 8, 10, and 15A-15C.

Selecting the portion of the stored data may include determining a threshold distance D. Then, for each obstacle O1 in the plurality of obstacles, a distance D1 between the obstacle O1 and the autonomous vehicle may be determined. A further determination may be made whether the threshold distance D is greater than the distance D1. If the threshold distance D is greater than the distance D1, the obstacle O1 may be identified as a candidate obstacle for the portion of the stored data. In particular embodiments, selecting the portion of the stored data may include selecting stored data for each candidate obstacle.

In some embodiments, selecting the portion of the stored data additionally may include making a determination of a number N of obstacles in the plurality of obstacles, where N>0. Then, for each candidate obstacle O2 in the plurality of obstacles, a determination may be made whether the candidate obstacle O2 is one of N obstacles closest to the autonomous vehicle. If the candidate obstacle O2 is one of the number N obstacles closest to the autonomous vehicle, stored data about the candidate obstacle O2 may be selected.

In further embodiments, selecting the portion of the stored data about the plurality of obstacles may include determining a threshold distance D2. Then, for each obstacle O1 in the plurality of obstacles, a determination may be made of a closest distance value D3 between the obstacle O1 and a closest point on the original trajectory to O1. The plurality of obstacles may be sorted based on the closest distance values D3. Stored data about for obstacles with a closest distance value D3 less than the threshold distance D2 may be selected.

At block 330, the portion of the stored data may be provided to an assistance center, such as discussed below in the context of at least FIGS. 10 and 15A-15C. In some embodiments, providing the portion of the stored data may include transmitting a request for navigational assistance, receiving a request for information regarding obstacles, and transmitting the portion of the stored data, such as discussed below in the context of at least FIG. 10. This communication may take place between the autonomous vehicle and the assistance center.

At block 340, a second trajectory may be received from the assistance center. The second trajectory might not be obstructed by the particular obstacle, such as discussed below in the context of at least FIGS. 8-10 and 15A-15C. In some embodiments, the second trajectory may meet the first trajectory at two or more points.

FIG. 4 is a flow chart of method 400, according to an example embodiment. Method 400 may be carried out by an assistance center, such as described below in the context of at least FIG. 17.

At block 410, the assistance center may receive a representation of a first trajectory of an autonomous vehicle that is in a stuck condition. The first trajectory might not relieve the stuck condition, such as discussed below in the context of at least FIGS. 8-10 and 15A-15C.

At block 420, the assistance center may receive sensor information of the autonomous vehicle, where the sensor information may include low-level sensor strike input and high-level, polygonal or polyhedral representations of objects in the vicinity of the autonomous vehicle. The high-level, polygonal or polyhedral representations of objects may be based at least in part on the low-level sensor strike input, such as discussed below in the context of at least FIGS. 8-10 and 15A-15C.

At block 430, the assistance center may, based on the first trajectory and the sensor information, determine a second trajectory that relieves the stuck condition while adhering to at least some navigational constraints. These navigational constraints may include, for instance, the autonomous vehicle avoiding collisions, obeying traffic laws, and/or not causing inertial discomfort to its passengers. Relieving the stuck condition may include ignoring at least one high-level, polygonal or polyhedral representation of an object that obstructs the first trajectory, such as discussed below in the context of at least FIGS. 8-10 and 15A-15C. In some embodiments, the first and second trajectories may be identical.

Determining the second trajectory may include determining that the first trajectory does not relieve the stuck condition. After determining that the first trajectory does not relieve the stuck condition, the second trajectory may be determined such that the second trajectory is different from the first trajectory and the second trajectory intersects the first trajectory at two or more points.

Alternatively or additionally, determining the second trajectory may include receiving a request for navigational assistance from the autonomous vehicle, transmitting a request for additional information from the assistance center to the autonomous vehicle, and receiving a proposed trajectory from the autonomous vehicle. The second trajectory may be based on the proposed trajectory, and the proposed trajectory may intersect the first trajectory at two or more points. In some of these embodiments, the second trajectory and the proposed trajectory may be identical, perhaps indicating that the assistance center has accepted the proposed trajectory.

In yet other embodiments, the second trajectory may be determined without human interaction. In still other embodiments, the second trajectory may be determined using a computing device at the assistance center, where the computing device is coupled to a graphical user interface configured to display autonomous vehicle trajectories, and where at least some of the second trajectory may be defined using the graphical user interface.

Method 400 may further include determining that the proposed trajectory relieves the stuck condition. Method 400 may additionally include determining that the proposed trajectory does not relieve the stuck condition, and modifying the proposed trajectory so that the modified proposed trajectory relieves the stuck condition. In these cases, the second trajectory may be the modified proposed trajectory.

At block 440, the assistance center may transmit a representation of the second trajectory and instructions for the autonomous vehicle to drive in accordance with the second trajectory, such as discussed below in the context of at least FIGS. 8-10 and 15A-15C.

In embodiments where the second trajectory is determined using a computing device at the assistance center, method 400 may further include estimating a network data rate between the autonomous vehicle and the computing device and requesting that the autonomous vehicle transmit location and sensor information to the assistance center such that the estimated data rate is not exceeded. This may involve estimating, or otherwise determining a maximum network data rate between the autonomous vehicle and the computing device and controlling the actual data rate between autonomous vehicle and the computing device so that it is no greater than the maximum data rate.

To that point, FIG. 5 shows an example autonomous vehicle operating environment 500 with a number of autonomous vehicles 510, 512, 514 in communication with assistance center 520 via network 522. In some embodiments, some or all of autonomous vehicles 510, 512, 514 may be capable of communicating with assistance center 520. Network 522 may include one or more networks, such as, but not limited to, one or more wireless wide area networks (WWANs) and/or wireless local area networks (WLANs). Each of autonomous vehicles 510, 512, 514 may be configured with a communication component at least for communicating with assistance center 520 and network 522. Also, assistance center 520 may be configured with a communications component for communicating with one or more of autonomous vehicles 510, 512, 514 and network 522. In some embodiments, some or all functions of assistance center 520 may be performed in an autonomous vehicle, perhaps by a human rider or driver.

FIG. 6 shows an example scenario 600 where an autonomous vehicle 610 is attempting to drive on road 602 according to original trajectory 630 to destination 632. However, autonomous vehicle 610 is in a stuck condition because original trajectory 630 is blocked by vehicle 614. Thus, navigation according to original trajectory 630 is not possible without adjusting a destination or trajectory of autonomous vehicle 610. Autonomous vehicle 602 may be configured to be able to drive on a left lane of road 602. However, in scenario 600, vehicle 612 blocks that trajectory. In scenario 600, vehicles 612, 614, 616, and 618 may be stopped or moving at a slow speed.

FIG. 7 shows an example method 700 for detecting whether an autonomous vehicle is in a stuck condition. At block 710, the autonomous vehicle may determine if it is either increasing speed and/or if a current speed of the autonomous vehicle is greater than a threshold speed of X meters per second (m/s). In some embodiments, X may be specified in dimensions other than meters per second; e.g., miles per hour, kilometers per hour, or feet per second. If the autonomous vehicle is either increasing speed or if the current speed of the autonomous vehicle is greater than X miles per hour, the autonomous vehicle is not stuck. In some cases, the autonomous vehicle may only determine whether its current speed is greater than the threshold speed.

Otherwise, at block 720, the autonomous vehicle may determine whether it has detected a traffic control signal. The traffic control signal may include a stop sign signal, a stop light signal, a warning sign signal, a warning light signal, yield signal, or some other type of signal that may indicate that the autonomous vehicle should be stopped or operating at a limited speed. If the autonomous vehicle has detected a traffic control signal, the autonomous vehicle is not stuck. Nonetheless, if an autonomous vehicle has been stationary or moving slowly in the presence of a traffic control signal for more than a threshold period of time, the autonomous vehicle may consider itself to be stuck. For instance, the autonomous vehicle may be stopped at a stop sign with its trajectory blocked by another vehicle.

Otherwise, at block 730, the autonomous vehicle may determine whether it is currently stopped awaiting user input. For example, the autonomous vehicle may be stopped while a user specifies a destination for the autonomous vehicle. If the autonomous vehicle is stopped awaiting user input, the autonomous vehicle is not stuck.

Otherwise, at block 740, the autonomous vehicle may identify a cause C for the autonomous vehicle not to be increasing speed and/or for the current speed less than or equal to the threshold speed. The cause C may be a cause based on a pedestrian, a cause based on a vehicle other than the autonomous vehicle, or a cause based on a particular type of object or an unknown object.

At block 750, the autonomous vehicle may set a timer T for T1 seconds, where T1 is based on the cause C. Table 1 below shows an example table of causes and corresponding T1 values.

TABLE 1 Cause T1 Vehicle 8 seconds Pedestrian 18 seconds Unknown object in trajectory 12 seconds

In some embodiments, additional causes to those shown in Table 1 may be identified by the autonomous vehicle, and consequently additional T1 values may be associated with the additional causes. In some cases, T1 values may differ from those specified in Table 1.

Alternatively or additionally, T1 values may be a function of blockage data for a location, where the autonomous vehicle may be stuck due to the nature of the location. For example, T1 values may be determined using a decision tree such as shown in Table 2 below:

TABLE 2 1. Has the autonomous vehicle traversed this location previously? a. Yes - have any vehicular obstacles been encountered at this location? i. Yes - has a vehicular obstacle been reported within a threshold period of time; e.g., 15 minutes? 1. Yes - set T1 = T1 value used for previous obstacle 2. No - set T1 = 10 seconds ii. No - is the blockage in the curbside lane? 1. Yes - set T1 = 12 seconds. 2. No - set T1 = 15 seconds. b. No - is the blockage in the curbside lane? i. Yes - set T1 = 12 seconds. ii. No - set T1 = 15 seconds.

In even other embodiments, T1 may be specified based on a combination of features including, but not limited to:

a day of week—e.g., useful for taking into account events like street cleaning days, working days, non-working days/holidays; property usage information—e.g., is the vehicle at or near building(s) where traffic may have fairly regular patterns, such as a school, a university, a factory, a hospital, a stadium or arena, an office campus, etc.; a time of day—e.g., schools tend to cause more blockages in the morning and early afternoon, factories and hospitals may have increased traffic at shift changing times, arenas may have increased traffic before and after an event; and/or a number of autonomous vehicles passing through this location per unit time as a measure of congestion. a number of non-autonomous vehicles passing through this location per unit time as a measure of congestion.



In still other embodiments, T1 may be specified using other units of time than seconds; e.g., tenths of seconds or minutes.

At block 752, timer T may run for T1 seconds; e.g., timer T may be started by the autonomous vehicle. At block 760, the autonomous vehicle may wait for timer T to expire; i.e., wait for at least T1 seconds.

At block 770, the autonomous vehicle may determine whether it is not increasing speed and/or cause C remains as the cause for the autonomous vehicle not to be increasing speed. If cause C does not remain, then the autonomous vehicle is no longer stuck. In some cases, there may be multiple causes for the autonomous vehicle to be stuck. Thus, the autonomous vehicle may examine its environment for another cause, and may attempt to address any further cause in accordance with the techniques described herein.

At block 780, the autonomous vehicle may determine that it is in a stuck condition and send an alert, such as an assistance signal, to indicate that the autonomous vehicle is stuck. In some embodiments, after completing block 780, method 700 may restart; e.g., method 700 may proceed to block 710.

Alternatively or additionally, the autonomous vehicle may process, in parallel, several causes that overlap in time. For instance, if the autonomous vehicle determines that there is another vehicle stopped in front of it and a pedestrian is also crossing the road in front of it, the autonomous vehicle may start two independent timers, one for the other vehicle and one for the pedestrian. If either timer expires, the autonomous vehicle may determine that it is in a stuck condition.

At block 790, the autonomous vehicle may determine that it is not in a stuck condition. In some embodiments, the autonomous vehicle may send an alert to the assistance center. This alert may be a “clear path” signal, to indicate that the autonomous vehicle is not stuck. In some embodiments, after completing the techniques of block 790, method 700 may restart; e.g., method 700 may proceed to block 710.

FIG. 8 shows an example scenario 800 where an autonomous vehicle 810 is attempting to drive on road 802 following original trajectory 830 to destination 832. However, autonomous vehicle 810 is in a stuck condition since original trajectory 830 is blocked by vehicle 814. In example scenario 800, vehicles 812, 814, 816, and/or 818 may be stopped or moving slowly (e.g., below a threshold speed).

Upon recognizing that it is in the stuck condition, autonomous vehicle 810 may send (perhaps wirelessly) an assistance signal to an assistance center (not shown in FIG. 8) to relieve the stuck condition. The assistance center may accept the assistance signal and request additional data from autonomous vehicle 810. Alternatively, autonomous vehicle 810 may provide the additional data to the assistance center before receiving such a request.

As mentioned above, heuristics may be applied to reduce the volume of data. One heuristic is to organize the obstacles by distance from the autonomous vehicle and/or to cap the number of obstacles to be the O nearest. Doing so may filter out any obstacles more than D meters away. For example, FIG. 8 shows that vehicle 814 is nearest to autonomous vehicle 810, and then vehicle 812, bottles 820, 822, 824, 826, and 828, and then vehicles 816 and 818. In some embodiments, D may be a function of the speed of autonomous vehicle 810; i.e., the faster the speed of autonomous vehicle 810, the larger the distance that should be considered. Thus, D may increase (or decrease) as the speed of autonomous vehicle 810 increases (or decreases).

Another heuristic may involve sorting obstacles by their distance from the nearest point on the trajectory of autonomous vehicle 810. Computing this set of obstacles may provide a more useful view of upcoming obstacles by prioritizing obstacles in the front of autonomous vehicle 810, but deprioritizing obstacles behind or off to the sides of autonomous vehicle 810. For example, with respect to new trajectory 836, FIG. 8 shows that new trajectory 836 comes closest to vehicle 814, then vehicles 816 and 812, bottles 820, 822, 824, 826, and 828, and then vehicle 818.

Even another heuristic is to prefer expert-friendly types of data for transmission. For example, human experts often may quickly analyze a condition of autonomous vehicle 810 using video data, or if video data is unavailable, using recent still images. Autonomous vehicle 810 may preferentially transmit video data (or still images) over other types of data, as this data is more likely to lead to resolution of the stuck condition than other types of data. In addition to these heuristics to reduce transmission load, throttling (i.e., only transmitting data every X seconds, or when there is a meaningful change) may also be used to further reduce load. Some or all of the herein-described heuristics may be used by autonomous vehicle 810 to provide data to the assistance center.

After receiving this data at the assistance center, an expert may propose new trajectory 836, which begins at a current position of autonomous vehicle 810 and finishes at endpoint 838, where new trajectory 836 joins original trajectory 830. (It is assumed that autonomous vehicle 810 can navigate according to new trajectory 836 without colliding with any objects—thus, FIG. 8, and possibly other figures as well, may not be drawn to scale.)

Upon reaching endpoint 838, autonomous vehicle 810 may switch from new trajectory 836 to original trajectory 830. After receiving and possibly validating new trajectory 836, autonomous vehicle 810 may drive according to new trajectory 836 to endpoint 838 and then according to original trajectory 830 to destination 832. In some embodiments, endpoint 838 might not be on original trajectory 830. Instead, endpoint 838 may allow autonomous vehicle 810 to proceed to a location that may partially relieve the stuck condition. From this location, autonomous vehicle 810 may calculate and/or drive according to one or more additional trajectories that may result in autonomous vehicle 810 eventually rejoining original trajectory 830.

FIG. 9 shows an example scenario 900 where autonomous vehicle 810 is attempting to drive on road 902 following original trajectory 930 to destination 932. Road 902 is similar to road 802 of FIG. 9. However, road 902 has shoulders 904, 906 while road 802 does not have shoulders. Associated with road 902 is sign 910 indicating that “SHOULDER RIDING” is “ALLOWED”. In example scenario 900, vehicles 812, 814, 816, and/or 818 may be stopped or moving slowly (e.g., below a threshold speed).

Scenario 900 shows that original trajectory 830 is blocked by vehicle 814. Although autonomous vehicle 810 may be permitted to drive on a left lane of road 902, vehicle 812 blocks that trajectory. Thus, autonomous vehicle 810 may be in a stuck condition.

In scenario 900, upon recognizing that it is in the stuck condition, autonomous vehicle 810 may send an assistance signal to an assistance center (not shown in FIG. 9) to relieve the stuck condition. As part of the assistance signal or in another communication, autonomous vehicle 810 may provide proposed trajectory 936 to the assistance center for consideration. For example, scenario 900 may have occurred after scenario 800 and autonomous vehicle 810 may have stored trajectory 836. Thus, autonomous vehicle 810 may have considered trajectory 836 for use in scenario 900 (possibly with slight modifications as bottles 820, 822, and 824 are slightly farther from vehicle 810), and proposed trajectory 936 based on the slightly-modified trajectory 836. As shown in FIG. 9, proposed trajectory 936 may rejoin original trajectory 930 at proposed endpoint (PEP) 938.

Upon receiving the assistance signal, the assistance center may request and subsequently receive additional information about autonomous vehicle 810 and its environment. In particular, an expert at the assistance center may be provided with image(s) and/or other information about sign 910, and so learn that shoulder riding is allowed. Then, the expert may examine information about shoulder 906 and determine that new trajectory 946 taking shoulder 906 may be used by autonomous vehicle 810 to bypass vehicle 814. As shown in FIG. 9, new trajectory 946 may rejoin original trajectory 930 at new endpoint (NEP) 948. New trajectory 946 has an advantage of generally keeping autonomous vehicle 810 further from obstacles. Therefore, the assistance center may reject proposed trajectory 936 in favor of new trajectory 940.

In providing new trajectory 946 to autonomous vehicle 810, the assistance center may provide a temporary override of any rules inhibiting autonomous vehicle 810 from shoulder riding at least while traveling on new trajectory 946. In scenario 900, autonomous vehicle 810 may receive new trajectory 946 with a temporary override allowing shoulder riding, verify new trajectory 946, and request the assistance center confirm new trajectory 946. Then, the assistance center may confirm new trajectory 946. Upon receiving confirmation of new trajectory 946, autonomous vehicle 810 may take new trajectory 946 to new endpoint 948. At new endpoint 948, autonomous vehicle 810 may rejoin original trajectory 930, and drive to destination 932, in accordance to original trajectory 930.

FIG. 10 is a flow chart of an example method 1000 that could be used in conjunction with either method 800, method 900, or other methods disclosed herein or defined elsewhere. In example method 1000, autonomous vehicle 1010 may request assistance from assistance center 520 to relieve a stuck condition. For instance, autonomous vehicle 1010 may determine that it is in a stuck condition and send assistance signal 1022 to assistance center 520. After receiving assistance signal 1022, assistance center 520 may send request 1024 to connect to autonomous vehicle 1010.

At block 1026, after connecting to autonomous vehicle 1010, an expert at assistance center 520 may assess a state of autonomous vehicle 1010. The expert may be a human expert, an expert system and/or other computer components, and/or a combination of human expert(s) and computer component(s).

At block 1030, the expert at assistance center 520 may determine whether or not assistance center 520 is to intervene with the navigation of autonomous vehicle 1010. If the expert at assistance center 520 determines to intervene, then assistance center 520 may send request 1032 to enter augmented mode. During augmented mode, autonomous vehicle 1010 may provide additional data to assistance center 520. This additional data may be a combination of location and sensor data from the autonomous vehicle.

At block 1040, autonomous vehicle 1010 may determine whether it should enter augmented mode. For example, autonomous vehicle 1010 may determine whether enough network capacity is available to transmit the necessary data, and/or perform other checks to determine whether or not augmented mode may be entered.

If autonomous vehicle 1010 determines that it should enter augmented mode, then autonomous vehicle 1010 may (periodically or from time to time) send additional data 1044 to assistance center 520. Autonomous vehicle 1010 may apply one or more heuristics to determine additional data 1044 prior to sending. Additional data 1044 may include low-level perceptual data about obstacles, high-level perceptual data about objects, video data, still images, location data and/or audio data. Further, as previously discussed, this additional data may be a subset of all environmental data available to autonomous vehicle 1010, selecting according to, for instance, relative importance.

In some embodiments, at block 1050, autonomous vehicle 1010 may propose a trajectory to relieve the stuck condition. The proposed trajectory may include a path from a current position of autonomous vehicle 1010 to an endpoint where the proposed trajectory joins an original trajectory that autonomous vehicle 1010 was utilizing prior to entering the stuck condition. Alternatively, endpoints that are not on the original trajectory may be used.

Autonomous vehicle 1010 may send proposed trajectory 1052 to assistance center 520. At block 1054, the expert at assistance center 520 may determine whether or not proposed trajectory 1052 relieves the stuck condition while adhering to the navigational constraints of autonomous vehicle 1010. These navigational constraints may include, for instance, the autonomous vehicle avoiding collisions, obeying traffic laws, and/or not causing inertial discomfort to its passengers. If the expert at assistance center 520 determines that this is the case, assistance center 520 may send confirmation 1056 of proposed trajectory 1052 to autonomous vehicle 1010.

If the expert at assistance center 520 determines that this is not the case, the expert at assistance center 520 may devise a trajectory to relieve the stuck condition. For example, the expert may modify an existing plan, modify a solution provided by autonomous vehicle 1010, or generate a new plan in order to devise the trajectory. The devised trajectory may include a path from the current position of autonomous vehicle to an endpoint where the devised trajectory joins the original trajectory of autonomous vehicle 1010, or to some other endpoint. Assistance center 520 may send devised trajectory 1062 to autonomous vehicle 1010.

At block 1064, autonomous vehicle 1010 may receive a representation of trajectory T, which may be either proposed trajectory 1052 or devised trajectory 1062. At block 1066, autonomous vehicle 1010 may determine whether or not it may follow trajectory T to relieve the stuck condition. For example, autonomous vehicle 1010 may determine that autonomous vehicle 1010 may actually execute the trajectory T without violating any rules of operation for autonomous vehicle 1010; e.g., traffic laws. As another example, autonomous vehicle 1010 may recheck locations of objects to verify that trajectory T will likely not lead to a collision.

If autonomous vehicle 1010 determines that it may follow trajectory T, autonomous vehicle 1010 may send final confirmation request 1070 for trajectory T. In some scenarios, autonomous vehicle 1010 may not be able to confirm trajectory T, for instance, due to a lack of sensor data regarding the safety of trajectory T. In these scenarios, autonomous vehicle 1010 may send a message to assistance center 520 rejecting trajectory T, perhaps including one or more reasons for rejecting trajectory T.

At block 1072, the expert at assistance center 520 may verify that trajectory T is valid; e.g., that trajectory T may relieve the stuck condition without violating the navigational constraints of autonomous vehicle 1010. If the expert at assistance center 520 verifies trajectory T, assistance center 520 may send confirmation 1080 of trajectory T to autonomous vehicle 1010. At block 1090, autonomous vehicle 1010 may drive according to trajectory T, to an endpoint of trajectory T, to relieve the stuck condition.

As autonomous vehicle 1010 drives according to trajectory T, autonomous vehicle 1010 may continue to receive new environmental data, such as new laser strike data. In cases where this new environmental data indicates that autonomous vehicle 1010 cannot follow trajectory T, autonomous vehicle 1010 may respond accordingly. For instance, based on the nature of the new environmental data, autonomous vehicle 1010 may avoid new obstacles, or once again determine that it is stuck. In this way, autonomous vehicle 1010 may avoid blindly following a trajectory when doing so puts autonomous vehicle 1010 at risk of colliding with another object.

Nonetheless, low-level data, such as clusters of laser strikes on surfaces in the vicinity of the autonomous vehicle, may be useful to the assistance center. FIG. 11 schematically illustrates a LIDAR unit 1102, perhaps mounted to, attached to, or part of an autonomous vehicle, scanning across an obstacle-filled environment. The example environment depicted in FIG. 11 includes a car 1110 and a tree 1112.

In operation, LIDAR unit 1102 may rotate according to motion reference arrow 1108 with angular velocity w. While rotating, LIDAR unit 1102 regularly (e.g., periodically or from time to time) emits laser beams, such as a laser beam 1106. Reflections from the emitted laser beams caused by objects in the environment, such as the car 1110 and the tree 1112, may be received by suitable sensors associated with LIDAR unit 1102. Time-stamping the receipt of the reflected signals allows for associating each reflected signal (if any is received at all) with the most recently emitted laser pulse, and measuring the time delay between emission of the laser pulse and reception of the reflected light.

The time delay provides an estimate of the distance to the reflective feature by scaling according to the speed of light in the intervening atmosphere. Combining the distance information for each reflected signal with the orientation of LIDAR unit 1102 for the respective pulse emission allows for determining a position of the reflective feature in three-dimensions.

In some embodiments, LIDAR unit 1102 may be configured to capture one or more laser point clouds of the environmental scene at predetermined time intervals, such as 100 milliseconds (for a refresh rate of 10 frames per second), 33 milliseconds (for a refresh rate of 30 frames per second), 1 millisecond, 1 second, etc.

In some embodiments, a single laser in LIDAR unit 1102 may have a scanning range of approximately 150 meters distance, a thirty degree vertical (“altitude”) field of view, and approximately a thirty degree horizontal (“azimuth”) field of view. Additional lasers included in LIDAR unit 1102 may have complementary ranges and fields of view as well so as to provide sufficient coverage of an environmental scene to inform navigational determinations.

FIG. 12 schematically illustrates an example point cloud corresponding to the obstacle-filled environmental scene of FIG. 11. Spatial-point data (represented by stars) are shown from a ground-plane (or aerial) perspective. Even though the individual points are not equally distributed in space throughout the sampled environment, adjacent sampled points are roughly equally spaced angularly with respect to LIDAR unit 1102. In some embodiments, point clouds may have as many as 50,000 laser-indicated points, 80,000 laser-indicated points, 100,000 laser-indicated points, etc. More or fewer laser-indicated points may be used.

Car spatial data 1214 may correspond to measured points on the surface of car 1110 with a line of sight to LIDAR unit 1102. Similarly, tree spatial data 1216 may correspond to measured points on the surface of tree 1112 visible from LIDAR unit 1102. The absence of points between car spatial data 1214 and tree spatial data 1216 indicates an absence of reflective features along the sampled line of sight paths in the plane illustrated.

Each point in the example point cloud illustrated in FIG. 12 may be referenced by an azimuth angle φ (e.g., the orientation of LIDAR unit 1102 while emitting the pulse corresponding to the point), which is determined by the orientation of a rotating angled mirror (not shown) of LIDAR unit 1102 and a line-of-sight (LOS) distance (e.g., the distance indicated by the time delay between pulse emission and reflected light reception). For emitted pulses that do not receive a reflected signal, the LOS distance may optionally be set to the maximum distance sensitivity of LIDAR unit 1102. The maximum distance sensitivity may be determined according to the maximum time delay the associated optical sensors wait for a return reflected signal following each pulse emission, which may itself be set according to the anticipated signal strength of a reflected signal at a particular distance given ambient lighting conditions, intensity of the emitted pulse, predicted reflectivity of environmental features, etc. In some examples, the maximum distance may be approximately 60 meters, 80 meters, 100 meters, or 150 meters, but other examples of maximum distance are possible for particular configurations of LIDAR unit 1102 and associated optical sensors.

In some embodiments, car spatial data 1214 may be low-level “strike input” data. This low-level data may be considered alone and/or in combination with additional sensor-indicated information, memory-based pattern-matching point clouds, and/or baseline maps of the environment to generate high-level, polygonal or polyhedral representations of objects in the environment. The high-level, polygonal or polyhedral representations may be generated by categorizing or identifying car spatial data 1214 as corresponding to car 1110 and generating a polygonal or polyhedral representation of car 1110. Similarly, tree spatial data 1216 may identified as corresponding to tree 1112 in accordance with a suitable object-detection technique and so lead to generation of a polygonal or polyhedral representation of tree 1112.

This processing may make use of an object detector. An object detector may be any configuration of software and/or hardware configured to perceive features in the environmental scene by categorizing object(s), identifying object(s), and/or generating polygonal or polyhedral representation(s) of categorized/identified objects based on the low-level laser point clouds captured by LIDAR unit 1102 and/or based on one or more of the sensors in the sensor system 1604. As a laser point cloud is captured via LIDAR unit 1102, data indicative of the captured point cloud is communicated to the object detector, which analyzes the data to determine whether there is an object present in the laser point cloud. Objects indicated by the point cloud may be, for example, a vehicle (e.g., car 1110) an obstacle (e.g., tree 1112), a pedestrian, a road sign, a traffic light, a traffic cone, etc.

To determine whether an object is present in a laser point cloud image, the object-detector software and/or module may associate arrangements of laser-indicated points with patterns matching objects, environmental features, and/or categories of objects or features. The object detector may be pre-loaded (or dynamically instructed) to associate arrangements according to one or more parameters corresponding to physical objects/features in the environment surrounding vehicle 1110. For example, the object detector may be pre-loaded with information indicating a typical height of a pedestrian, a length of a typical automobile, confidence thresholds for classifying suspected objects, etc.

If an object (or objects) is present in the point cloud, the object detector may generate a polygonal or polyhedral representation corresponding to the object. For example, when the object detector identifies an object in a point cloud, the object detector may define a bounding box encompassing the object. The bounding box may correspond to a predicted exterior surface of the point cloud indicated object. Of course, the bounding “box” may generally take the form of a multi-sided polygon or polyhedron defining the predicted outer boundaries of the object.

For each captured point cloud, positions of perceived objects and their corresponding boundary definitions are associated with a frame number or frame time. Thus, similarly shaped objects appearing in the same or roughly similar locations in successive scans of the scene may be associated with one another to track objects in time. Perceived objects appearing in multiple point cloud frames (e.g., complete scans of the scanning zone), may be considered to be the same object, and may be either stationary or in motion relative to vehicle 1110. Each perceived object may be associated, for each frame on which the perceived object appears, with a distinct bounding shape defining the dimensional extent of the perceived object.

Further, as noted above, each spatial point may be associated with a respective laser from a set of lasers and a respective timestamp. That is, in an embodiment where LIDAR unit 1102 includes multiple lasers, each respective spatial point may be associated with the particular laser that detected the respective spatial point. Additionally, each respective spatial point may be associated with a respective timestamp (e.g., a time at which the particular laser was emitted or received). In this way, the received spatial points may be organized, identified, or otherwise ordered on a spatial (laser identification) and/or temporal (timestamp) basis. Such an ordering may assist or improve an analysis of the spatial point data by allowing for organizing the spatial point data into a meaningful order. Some or all of the laser strike data, point cloud data, and/or object-related bounding box data may be stored by the autonomous vehicle.

FIG. 13 schematically illustrates spatial point data indicative of a surface of a target vehicle that is stationary relative to a LIDAR unit, according to an example embodiment. The LIDAR unit may be mounted on an autonomous vehicle or otherwise integrated or associated with an autonomous vehicle. In this example, a target surface 1318 is identified from a set of spatial points indicative of locations of reflective surfaces received from LIDAR unit 1102 by an object-detection technique mentioned herein and/or any other known or later developed. In some embodiments, the set of spatial points is received from a single sweep of LIDAR unit 1102. Target surface 1318 may be a front or rear surface of a target vehicle, such as vehicle 1110.

In this example, a first point 1320 and a second point 1326 are also identified by an object-detection technique mentioned herein and/or any other known or later developed. The first point 1320 is indicative of a first location 1322 on target surface 1318 obtained from LIDAR unit 1102 at a first time 1324, and the second point 1326 is indicative of a second location 1328 on target surface 1318 obtained from LIDAR unit 1102 at a second time 1330. Other points illustrated in FIG. 13 may be indicative of other locations on target surface 1318 obtained from LIDAR unit 1102 at other times. With this arrangement, a speed of target surface 1318 relative to LIDAR unit 1102 may be estimated based on the first location 1322, the first time 1324, the second location 1328, and the second time 1330.

In this example, the estimate of a relative speed of target surface 1318 may be determined based on an offset between first location 1322 and second location 1328 divided by a time difference between the second time 1330 and the first time 1324.

As illustrated in FIG. 13, a coordinate frame 1332 includes a longitudinal axis 1334. In this example, target surface 1318 is perpendicular to the longitudinal axis 1334. A projected first point 1336 may be determined by projecting the first point 1320 onto the longitudinal axis 1334, and a second point 1338 may be determined by projecting the second point 1326 onto the longitudinal axis 1334. With this arrangement, the offset between the first location 1322 and the second location 1328 is determined as a distance between the projected first point 1336 and the projected second point 1338.

In this example, the offset is zero because the projected first point 1336 and the projected second point 1338 are each at the same location on the longitudinal axis 1334. Accordingly, the estimate of the speed of target surface 1318 in this example is zero.

In some embodiments, the coordinate frame 1332 may include a fixed coordinate frame in an environment of LIDAR unit 1102 based on data from an inertial measurement unit (IMU) associated with a vehicle. However, in some embodiments, the defining of a coordinate frame may also be based at least in part on data from other sensors associated with the vehicle. For instance, the defining of a coordinate frame may also be based at least in part on data from a GPS associated with the vehicle. Doing so may improve estimates of the speed and trajectory of target surface 1318. Other examples are also possible.

In some embodiments, the longitudinal axis 1334 may be defined based on a direction of motion of LIDAR unit 1102 and/or a direction of motion of target surface 1318. In some examples, the direction of motion of LIDAR unit 1102 is known. However, in other examples, the direction of motion of LIDAR unit 1102 may be identified based on any technique mentioned herein and/or any other known or later developed. For instance, the direction of motion of LIDAR unit 1102 may be identified based on a direction of a path that LIDAR unit 1102 is traveling, such as a roadway or a traffic lane. In some examples, the direction of motion of target surface 1318 is known. However, in other examples, the direction of motion of target surface 1318 may be identified based on any technique mentioned herein and/or any other known or later developed.

FIG. 14 schematically illustrates spatial point data indicative of a surface of a target vehicle that is moving relative to the LIDAR unit, according to an example embodiment. In this example, a first point 1440 and a second point 1446 on target surface 1318 are also identified by an object-detection technique discussed herein and/or any others known or later developed. First point 1440 is indicative of a first location 1442 on target surface 1318 obtained from LIDAR unit 1102 at a first time 1444, and second point 1446 is indicative of a second location 1448 on target surface 1318 obtained from LIDAR unit 1102 at a second time 1450. Other points illustrated in FIG. 14 may be indicative of other locations on target surface 1318 obtained from LIDAR unit 1102 at other times.

In this example, target surface 1318 has a known direction of motion 1458. Further, an estimate of a speed of target surface 1318 may be determined based on an offset between first location 1442 and second location 1448 divided by a time difference between second time 1450 and first time 1444.

A projected first point 1452 may be determined by projecting first point 1440 onto longitudinal axis 1334, and a projected second point 1454 may be determined by projecting second point 1446 onto longitudinal axis 1334. With this arrangement, the offset between first location 1442 and second location 1448 may be determined as a distance between projected first point 1452 and projected second point 1454. The offset is greater than zero because projected first point 1452 and projected second point 1454 are separated by a non-zero distance on longitudinal axis 1334. Accordingly, the estimate of the speed of target surface 1318 is greater than zero. As illustrated in FIG. 14, the distance may represent a longitudinal distance traveled 1456 by target surface 1318.

FIGS. 15A, 15B, and 15C show scenario 1500 using trajectory user interface (UI) 1510 to relieve a stuck condition of an autonomous vehicle. In some embodiments, trajectory UI 1510 may be provided using a graphical user interface (GUI) of a computing device. For example, trajectory UI 1510 may utilize one or more windows, buttons, dialogs, and other components of the GUI. In scenario 1500, trajectory UI 1510 may be utilized at an assistance center, such as assistance center 520, and may be configured to communicate with one or more autonomous vehicles and with one or more experts. The expert(s) may be human experts and/or computing components, such as but not limited to expert systems. Alternatively or additionally, trajectory UI 1510 may be utilized in an autonomous vehicle, perhaps by a passenger of the autonomous vehicle.

FIG. 15A shows a display of trajectory UI 1510 including an autonomous vehicle/data selection section 1511, autonomous vehicle display 1520, and a display control section 1570. In some embodiments, more, less, or different sections and/or displays may be provided using trajectory UI 1510.

Autonomous vehicle/data selection section 1511 includes autonomous vehicle selection button 1512, video data button 1514, low-level data button 1516, and high-level data button 1518. In some embodiments, more, less, or different buttons may be provided in the autonomous vehicle/data selection section of trajectory UI 1510.

In FIGS. 15A-15C, buttons that are selected are shown with a gray background, while buttons that are not selected are shown with a white background. For example, in scenario 1500, high-level data button 1518 is selected, while autonomous vehicle selection button 1512, video data button 1514 and low-level data button 1516 are not selected.

Upon selection, autonomous vehicle selection button 1512 may instruct trajectory UI 1510 to display a dialog or similar graphical component (not shown in the figures) listing autonomous vehicles seeking assistance. An expert may use the dialog to select an autonomous vehicle to assist, and upon selection, begin communication with the selected autonomous vehicle. Once an autonomous vehicle is selected for assistance, trajectory UI 1510 may display an identifier and/or other information for the selected autonomous vehicle. FIG. 15A shows an identifier “AVx123” for an autonomous vehicle selected for assistance during scenario 1500. Then, when the expert has finished assisting the selected autonomous vehicle, the expert may use autonomous vehicle selection button 1512 to select another autonomous vehicle to be assisted, assuming that another autonomous vehicle has requested assistance.

Video data button 1514, when selected, may be used to generate a request to a selected autonomous vehicle to provide video data. The video data may include sequences of images configured for display in succession at a constant rate and/or still images. Once video data is available, trajectory UI 1510 may display the video data using autonomous vehicle display 1520 and/or using another display or window. In some embodiments, if more than one of buttons 1514, 1516, and 1518 are selected, separate displays or windows may be provided by trajectory UI 1510 for each type of data; e.g., video data associated with button 1514, low-level data associated with button 1516, and high-level data associated with button 1514. Low-level data and high-level data are discussed below in more detail at least in the context of FIG. 16. Alternatively or additionally, some or all of video data, low-level data, and high-level data may be combined into one display.

Low-level data button 1516, when selected, may generate a request to a selected autonomous vehicle to provide low-level data. When the low-level data is available, the low-level data may be displayed using autonomous vehicle display 1520 and/or using another display or window. High-level data button 1518, when selected, may generate a request to a selected autonomous vehicle to provide high-level data. When the high-level data is available, the high-level data may be displayed using autonomous vehicle display 1520 and/or using another display or window.

In some embodiments, the autonomous vehicle selects data for transmission to the assistance center. In these embodiments, selection of one of buttons 1514, 1516, or 1518 may not lead to a request for data; rather, trajectory UI 1510 may indicate that such data is available by changing display of buttons 1514, 1516, and/or 1518 to indicate data availability. Then, if the expert selects a button associated with available data, the data may be displayed using autonomous vehicle window 1520 or another window. And, upon selection of a button not associated with available data, an error message/dialog may be generated indicating the unavailability of the selected data. In particular embodiments, even if the autonomous vehicle selects data for transmission, the autonomous vehicle may honor a request for data, and in these embodiments, upon selection of a button not associated with available data, a request for the data may be sent to the autonomous vehicle.

In scenario 1500, high-level data is provided by the autonomous vehicle and is selected, as indicated by the gray background of button 1518 in FIG. 15A. As such, autonomous vehicle display 1520 shows high-level data, represented as graphical objects, representing autonomous vehicle AVx123 1530, road 1532, gates 1534a, 1534b, bovines 1542, 1544, and calves 1546 and 1548. In scenario 1500, bovines 1542, 1544 and calves 1546, 1548 are travelling to the left, crossing road 1532 to enter a field (not shown) accessible via an opening between gate 1534a and gate 1534b. Autonomous vehicle AVx123 1530 has an original trajectory 1540 that would impact bovine 1542 at or shortly after time “17:23:04 PDT”.

As such, autonomous vehicle AVx123 1530 is in a stuck condition. In scenario 1500, prior to requesting assistance, autonomous vehicle AVx123 1530 may have waited for a timer to expire upon determining this stuck condition, such as discussed in detail in the context of FIG. 7, based on a cause that bovines 1542, 1544 and calves 1546, 1548 are obstructing trajectory 1540. At 17:23:04 PDT, as shown in FIG. 15A, only bovine 1542 remains obstructing trajectory 1540.

Display controls section 1570 of trajectory UI 1510 is shown in FIG. 15A with six buttons: show autonomous vehicle trajectory button 1580, show attractors button 1582, show repellers button 1584, draw new trajectory button 1586, send new trajectory button 1588, and approve trajectory button 1590. FIG. 15A shows that buttons 1580 and 1584 are selected and buttons 1582, 1586, 1588, and 1590 are not selected. In some embodiments, more, less, or different buttons are provided in the display controls section of trajectory UI 1510.

Autonomous vehicle trajectory button 1580, when selected, instructs autonomous vehicle display 1520 to display a trajectory for the selected autonomous vehicle. As autonomous vehicle trajectory button 1580 is selected, trajectory 1540 for selected autonomous vehicle AVx123 is displayed on display 1520. FIG. 15A shows trajectory 1540 as an arrow from a display of high-level object 1530 representing AVx123 going toward the top of the figure. In some embodiments, if autonomous vehicle trajectory button 1580 were selected again, autonomous vehicle trajectory button 1580 may act as a toggle and display 1520 would no longer display trajectory 1540.

Show attractors button 1582 may, when selected, instruct autonomous vehicle display 1520 to show “attractors.” Similarly, show repellers button 1584 may, when selected, instruct autonomous vehicle display 1520 to show “repellers.” In some embodiments, providing trajectories to an autonomous vehicle may be modeled as an energy minimization problem defined by a series of attractors and repellers. These attractors and repellers may be placed by an expert, or may be automatically determined by autonomous vehicle AVx123.

One or more attractors, or positive potentials, may exist or may be inserted along a center of a lane of road 1532. Attractors may be placed in other positions that are desirable for autonomous vehicle travel. Attractors are not explicitly shown in FIGS. 15A, 15B, and 15C.

Repellers, or negative potentials, may exist or may be inserted at undesirable positions, such at the edges of lanes and surrounding obstacles that may partially or completely block a trajectory of an autonomous vehicle. In FIGS. 15A-15C, repellers are shown in autonomous vehicle display 1520 as dashed lines. For instance, repellers 1542r, 1544r, 1546r, 1548r exist around bovines/calves 1542, 1544, 1546, 1548, respectively. Repellers are also shown near the edges of road 1532.

In some embodiments, an expert may specify an endpoint and a series of attractors and repellers with controls for varying the strength and radius of effect of these potentials. These data may be provided to autonomous vehicle AVx123 to define a new trajectory that tries to take attractive paths and avoid repelled paths.

Draw new trajectory button 1586, when selected, allows the expert to enter an augmented trajectory for autonomous vehicle AVx123. Send new trajectory button 1588, when selected, allows the expert to send the augmented trajectory for autonomous vehicle AVx123. Approve trajectory button 1590, when selected, allows the expert to send a message to the autonomous vehicle that approves a trajectory sent by autonomous vehicle AVx123. Once a trajectory is approved, autonomous vehicle AVx123 may drive along the approved trajectory to relieve a stuck condition, or for another purpose.

In some embodiments, an augmented or new trajectory for an autonomous vehicle may be specified based on two points: a point of departure from an existing trajectory and an endpoint. The endpoint may be a point of return to the existing trajectory or a point that is not part of the existing trajectory. For instance, the endpoint might specify a location to which the autonomous vehicle can drive that at least partially relieves the stuck condition. In particular embodiments, the point of departure may be inferred as a current position of the autonomous vehicle, and so only the point of return may be explicitly specified.

The trajectory may also include collection of waypoints to navigate between (i) the point of departure or a current position, and (ii) the endpoint of the trajectory. The collection of waypoints may be specified using a spline, which is a piecewise-smooth function connected by the waypoints. Upon reaching the endpoint, the autonomous vehicle may continue with the original trajectory. In some embodiments, some or all of the collection of waypoints may be specified other than by a spline; e.g., using piecewise linear functions, other piecewise-smooth functions, polynomials, lists of waypoints, etc.

Turning to FIG. 15B, scenario 1500 continues at time “17:23:49 PDT” where autonomous vehicle AVx123 has provided a proposed trajectory 1550 and proposed maximum speed 1552 to relieve the stuck condition. FIG. 15B shows that autonomous vehicle display 1520 portrays proposed trajectory 1550 as a relatively thin arrow from a starting point or point of departure, shown as the letter “s” in a circle, through a waypoint shown as the letter “A” in a circle, to an endpoint or point of return, shown as the letter “e” in a circle. In some embodiments, an autonomous vehicle may propose a maximum speed to travel on a proposed trajectory. FIG. 15B shows the proposed maximum speed 1552 for trajectory 1550 of 1.2 meters/second. In some embodiments, an autonomous vehicle may propose a trajectory to relieve a stuck condition (or for some other purpose) without proposing a related speed, such as a maximum, minimum or average speed. Alternatively or additionally, the autonomous vehicle may also or instead propose minimum and/or average speeds.

Upon reviewing proposed trajectory 1550, the expert may determine that proposed trajectory 1550 may come too close to bovine 1542. Then, the expert may specify a different trajectory than proposed trajectory 1550. In scenario 1500, as shown in FIG. 15B, the expert may press draw new trajectory button 1586 to specify a trajectory.

FIG. 15C shows that scenario 1500 continues at time “17:24:04 PDT” with draw new trajectory button 1586 selected. The expert has also specified new trajectory 1560 connecting the point of departure “s” and the point of return “e” of proposed trajectory 1550 using spline 1564 with three waypoints. The new trajectory 1560 takes a wider path around bovine 1542, and should be safer for autonomous vehicle AVx123 than proposed trajectory 1550. In scenario 1500, a maximum speed for traveling along trajectory 1560 may be specified by dialog 1562, which shows a current maximum speed selection of 1.2 meters per second, a “+” button for incrementing the maximum speed, and an “−” for decrementing the maximum speed.

FIG. 15C shows spline 1564 using a dotted and dashed line connecting points “s” and “e” and the three waypoints using circled numbers “1”, “2”, and “3”. In some embodiments, different techniques may be used to display trajectories proposed by autonomous vehicles and/or by experts; e.g., different colors, fonts, characters, etc. may be used to distinguish trajectories.

Feedback may be used to aid an expert in drawing a trajectory. For example, if show repellers button 1584 is selected, as shown in FIG. 15C, then trajectory interface 1510 may generate a vibration, sound, or graphical indication when a drawn trajectory touches a repeller or an object. As another example, if show attractors button 1582 is selected, trajectories may be pre-selected by trajectory interface 1510 that partially or completely follow one or more attractors that are unobstructed by objects. Other examples are possible as well.

While not shown in the figures, scenario 1500 may continue with the expert pressing send new trajectory button 1588. Pressing send new trajectory button 1588 may instruct trajectory interface 1510 to send trajectory 1560 to autonomous vehicle AVx123. Autonomous vehicle AVx123 may then examine trajectory 1560 and request approval of the trajectory. Upon receiving the request, trajectory interface 1510 may provide an indication of the request for approval. Then, the expert may press the approve trajectory 1590 button to send an approval to autonomous vehicle AVx123. Autonomous vehicle AVx123 may then drive along trajectory 1560 from point of departure “s” via waypoints “1”, “2”, and “3” to reach point of return “e”. Upon reaching point “e”, the stuck condition for autonomous vehicle AVx123 is relieved and scenario 1500 may end.

FIG. 16 shows a block diagram of components of an example autonomous vehicle 1600. In some embodiments, autonomous vehicle 1600 may include at least some of the herein-described functionality of autonomous vehicles 510, 512, 514, 610, 810, 1010, and 1800. Additionally, autonomous vehicle 1600 may be configured to operate in an operational mode, such as a non-autonomous mode, a partially-autonomous mode, or an autonomous-operation mode.

The non-autonomous mode may use human input to select and execute driving behaviors during operation of the autonomous vehicle. In some instances, while in non-autonomous mode, the autonomous vehicle may operate like a traditional, non-autonomous vehicle.

The partially-autonomous mode may involve both a vehicle control system, such as control system 1606 of autonomous vehicle 1600, and human inputs to select driving behaviors during operation of autonomous vehicle 1600. For example, the autonomous vehicle control system may generate indications of driving behaviors for review by a human driver. For each indication, the human driver may review the indication and operate the autonomous vehicle by carrying out, modifying, or ignoring the indication. In some cases, the partially-autonomous mode may involve the autonomous vehicle performing all actions to navigate and drive the autonomous vehicle, where a human driver may monitor the autonomous vehicle's performance and intervene if and when necessary; e.g., to avert an accident. In other cases, as described herein, autonomous vehicle 1600 may request assistance from an assistance center; e.g., assistance center 520. Additional techniques for operating an autonomous vehicle in a partially-autonomous mode, such as auto-piloting and automatic parking, are possible as well.

In the autonomous-operation mode, the autonomous vehicle control system may select and execute driving behaviors along at least part of a route without human input. The autonomous-operation mode may be subdivided into an autonomous mode utilizing a trained driver, an autonomous mode with a non-trained human driver, and an autonomous mode without a human driver. In autonomous-mode operation with a human driver, the vehicle control 1606 system may be configured to receive feedback from the human passenger about driving quality of the autonomous vehicle, and, in some circumstances, for the human driver to operate the autonomous vehicle.

Autonomous vehicle 1600 may include various systems such as a propulsion system 1602, a sensor system 1604, a control system 1606, one or more peripherals 1608, as well as a power supply 1670, a computing device 1680, and a user interface 1690. Autonomous vehicle 1600 may include more or fewer systems and each system may include multiple aspects. Further, each of the systems and aspects of autonomous vehicle 1600 may be interconnected. Thus, one or more of the described functions of autonomous vehicle 1600 may be divided into additional functional or physical components, or combined into fewer functional or physical components. In some further examples, additional functional and/or physical components may be added to the examples illustrated by FIG. 16.

Propulsion system 1602 may include components operable to provide powered motion for autonomous vehicle 1600. In an example embodiment, propulsion system 1602 may include an engine/motor 1610, an energy source 1612, a transmission 1614, and wheels/tires 1616. Engine/motor 1610 may be any combination of an internal combustion engine, an electric motor, steam engine, Stirling engine, or other types of engines and/or motors. In some embodiments, engine/motor 1610 may be configured to convert energy source 1612 into mechanical energy. Propulsion system 1602 may include multiple types of engines and/or motors. For instance, a gas-electric hybrid car may include a gasoline engine and an electric motor. Other examples are possible.

Energy source 1612 may represent a source of energy that may, in full or in part, power engine/motor 1610. That is, engine/motor 1610 may be configured to convert energy source 1612 into mechanical energy. Examples of energy sources 1612 include gasoline, diesel, other petroleum-based fuels, propane, other compressed gas-based fuels, ethanol, solar panels, batteries, and other sources of electrical power. Energy source 1612 may additionally or alternatively include any combination of fuel tanks, batteries, capacitors, and/or flywheels. Energy source 1612 may also provide energy for other systems of autonomous vehicle 1600.

Transmission 1614 may include aspects that are operable to transmit mechanical power from engine/motor 1610 to wheels/tires 1616. To this end, transmission 1614 may include a gearbox, clutch, differential, and drive shafts. Transmission 1614 may include other aspects. The drive shafts may include one or more axles that may be coupled to the one or more wheels/tires 1616.

Wheels/tires 1616 of autonomous vehicle 1600 may be configured in various formats, including a unicycle, bicycle/motorcycle, tricycle, or car/truck four-wheel format. Other wheel/tire geometries are possible, such as those including six or more wheels. Any combination of wheels/tires 1616 of autonomous vehicle 1600 may be operable to rotate differentially with respect to other wheels/tires 1616. Wheels/tires 1616 may represent at least one wheel that is fixedly attached to transmission 1614 and at least one tire coupled to a rim of the wheel that may make contact with the driving surface. Wheels/tires 1616 may include any combination of metal and rubber, or another combination of materials.

Sensor system 1604 may include a number of sensors configured