Cars can now virtually park themselves. Having spent time in several of today's semi-automated self-parking cars, it's become clear that the idea is becoming mainstream, but the technology behind it is not commonly understood. Here's a rundown on how it works.

Many people have long contended that the selling point for autonomous cars will be when people can use them to pull up to the front door of a store, get out of the car, and tell it to go park itself. Then, when shopping is done, a quick call on the smartphone brings the car back to the front door. This autonomous valet and its convenience will be what truly sells most people on autonomous vehicle technologies. Safety concerns don't sell things. Appeals to laziness do.

Knowing that, eyeing the first major step in self-driving cars is a good way to understand how autonomous driving technology works.

Volkswagen illustrates its past and present technology progression through the first four steps of the five-step automated vehicle ladder, defined by the Society of Automotive Engineers Volkswagen

Autonomous parking was introduced, physically, about 20 years ago in research prototypes for parallel parking vehicles. Most humans find parallel parking to be difficult to master. There are many reasons for this, but this difficulty and the fact that many space-conscious parking spaces in urban environments require parallel parking has lead to this being a prime area of research for autonomous vehicles. The first vehicle to parallel park was a prototype built in France by the Institut National de Recherche en Informatique et an Automatique (INRIA), setting the foundation for what has now become commercially available in self-parking vehicles.

Most major automotive manufacturers are now working on automated or semi-automated parking. Early leaders in the tech were Volvo, Volkswagen, and Toyota. Most manufacturers such as Ford, BMW, Mercedes-Benz, Fiat Chrysler Automobiles, Toyota, and Volkswagen have introduced semi-automated parking systems in their vehicles. All are using systems designed from the basic array of tech developed by INRIA. The findings of the INRIA research eventually became the general standard for the industry through the Society of Automotive Engineers (SAE) J3016 standards.

The J3016 standard defines Driver Assistance such as semi-automated and automated parking. SAE J3016 includes five distinct levels of vehicle automation – including park assist technologies – the first three being progressions of assisted parking (Driver Assistance, Partial Automation, Conditional Automation), the fourth being near-automated (High Automation), and the fifth being totally automated vehicle operations (Full Automation). Most vehicles on the road today with assisted parking capability fall into level 2 or 3.

The basic procedure for parallel parking starts with finding a suitable parking space. Assessing the best approach for getting into that space is done by considering variables such as the space's size, the amount of room available for maneuver, and the capabilities of the vehicle to be parked. Humans can (theoretically) do this quickly and without much conscious thought. Computers require a little more training.

Sensors on the front and rear bumpers of a vehicle can be used to detect most of the variables involved. Proximity sensors for park-assist usually use electromagnetic or ultrasonic detection to determine the distance to and size of an object near the vehicle. The more common ultrasonic sensors work in a way similar to the echolocation bats use to find their way around. Once distances are determined, calculations are made by the parking system's computer to set the best course of action for parking. Since some control is still usually in the hands of the driver (mostly forward-reverse and braking), adjustments have to be made to accommodate mistakes made by the human involved.

In a Ford vehicle, for example, we have parallel parked using the above basic steps. When parking assistance is activated, the vehicle senses the available space and alerts the driver. It then begins instructions for setting up, including letting go of the steering wheel (touching the wheel to interfere with self-parking disengages the assisted parking). When the vehicle is in place, it instructs the driver as to whether braking, gear changes, or other driver-controlled portions of the procedure are required.

The vehicle otherwise steers itself into the slot and announces the completion of parking with a tone and visual image. The first few times an experienced driver tries this system it seems highly foreign, and the urge to grab the steering wheel or apply too much brake is high. This subsides after a few tries, though, and leaves one amazed at how well the system parks the vehicle, even in what would seem to be impossible spaces.

Assisted or self-parking is the logical first step towards commercialization of self-driving and fully autonomous vehicles like this prototype train of Ford Focus sedans Ford

Parallel parking is the more common of the semi-automated and automated parking systems available commercially, but perpendicular and angled parking are now also offered by many manufacturers. We have been in Ford, Fiat Chrysler, General Motors, and Volkswagen vehicles capable of both parallel and perpendicular (back-in or nose-in) parking. We've also tried angled parking in Toyota vehicles. These vehicles can also usually pull out of their space when directed, which is especially useful in backing out of perpendicular spots in tight quarters and in exiting from tight parallel spaces. As calculating techniques become more sophisticated, obstacles such as irregular spaces, moving objects (pedestrians, bicycles), or curved surfaces (irregular curbs) can be accounted for in parking maneuvers.

Fully autonomous parking is still currently a dream in terms of what's available to car buyers. It's a dream that may soon be reality, however, as companies such as Bosch and major auto manufacturers are working towards that goal as a near-future option. Volkswagen recently introduced "Trained Parking" in which a car can be "taught" to find a parking place, such as at home or at work, that is used routinely and then left to get into that spot without a driver present.

Self-parking is the first big step towards fully automated vehicles. Several manufacturers such as Nissan, Tesla, Ford, and Jaguar Land Rover have shown prototypes that can be controlled via remote control or that are capable of fully parking themselves without any input from the driver. Most in the industry are expecting fully automated vehicles to begin availability by 2020, likely with self-parking or nearly autonomous parking as a primary feature.

Sources: SAE [2]