Rethink Robotics (formerly Heartland Robotics) has come out of stealth mode with the announcement of Baxter -- a $22,000 dual-arm, human-scale robot with compliant joints. The details are available in Rethink Robotics' Baxter datasheet and brochure, but here are a few key highlights: dual 7-DoF arms with 5 lb (2.3kg) payload with a max no-load speed of 3.3 ft/sec (1m/sec). The arms are compliant owing to series-elastic actuators (SEAs) with force control and torque sensing at each joint. The robot torso sans-pedistal is 3'1" tall (94cm), and the robot has a reach of roughly 104cm. The robot weighs in at 165 lbs (75kg) and has a suite of sensors including: 5 camers (1 up top, 2 in the torso, and 2 "eye-in-hand"), a 360-deg. ring of ultrasonic range sensors in the head, and IR range sensors at the gripper, and (naturally) kinematics and torque sensing at each joint. Did I mention the starting price of $22,000 and that it starts shipping this October!?! This will be a HUGE deal for robotics. Comparable arms easily cost an order of magnitude more (~$100k each), so getting a full pair for $22k is going to completely change the game -- perhaps even more than the Kinect. It's an exciting time for robotics! Read on for pictures, an interview with Rod Brooks (CTO and co-founder of Rethink), and the press release.

Meet Baxter from Rethink Robotics

Interview with Rod Brooks

Rod Brooks is the CTO and co-founder of Rethink Robotics (and co-founder of iRobot, former CSAIL director at MIT, and my academic grandfather). Rethink and Rod afforded me a great privilege: a half-hour conversation the day preceding the launch. Here's a rough summary based on my quick notes (Rod, correct me if I make any egregious mistakes):

Hardware and Software Details:

Travis: In terms of sensing, you have the 5 cameras, some ultrasound sensors, kinematics, and joint torques. Why no 3D sensing (a la the Kinect or depth cameras)? How extensible is your hardware?

Rod: There are 5 cameras: one above the screen, two in the chest, and two "eye in hand" (wrist-mounted) cameras to help with manipulation. There's also the 360-degree sonar ring (eg. to detect people coming up behind the robot) and IR range sensors in each hand. Plus the kinematics and torques. We wanted to integrate a Kinect-like sensor, but it debuted too late in the development process.

We knew that this platform would be popular with researchers. The gripper is exchangeable. The entire system is self-contained -- no bulky external boxes [Travis: I'm looking at you, Kuka!]. We're running off a quad-core Intel machine, so there's plenty of computation. We've also included USB and ethernet onboard, so extensibility shouldn't be a problem.

Travis: On the software front...?

Rod: We plan to release a SDK to allow researchers to modify the system. It will be based on ROS.

Travis: I'm a mobile manipulation guy.... why no mobile base?

Rod: Not in this version. Two reasons. First, we already had a lot of complexity in 14-DoF worth of arms. Second, our early case studies suggested that mobility would only be useful in 3% of factory-type tasks -- such as standing stationary and doing small-object pick-and-place. [Travis: Fascinating! Wouldn't have guessed it was that low. Building a quick plug-and-play mobile base for research labs could be a nice little startup opportunity! Lots of labs will want 'em.]

Travis: OK, my one real gripe about existing hardware: it looks like its lacking a true wrist (ie. spherical joint at the end effector). Why?

Rod: Mechanical complexity and cost tradeoff. To keep the price reasonable, we have some clever gearboxes designs... the complexity of a true wrist would've been too much.

Baxter's common sense:

Travis: In the press release, it says Baxter can "Apply common sense to its environment." From a research perspective, that seems pretty vacuous. What does that even mean?

Rod: Indeed. We don't mean "common sense" from a Marvin Minsky-like strong AI perspective. Baxter's "execution" application consists of a series of behavior-based systems. During "training," the robot detects task-relevant features and uses it to build up the behavior based system.

For example, let's say a user is training the robot for a pick and place task. During the "pick" phase, a user places the gripper above an object and closes the gripper. The force on the gripper is detected by the robot. Our "training" application detects this sequence as "the robot is grasping an object"... so during "execution", Baxter won't proceed unless it actually detects an object in the robots gripper. Thus, if the object fell out, it would stop (or do something else). This is different from how existing industrial robots work -- they'd just merrily continue the pick-and-place without the object.

Collectively, these "behavior primitives" [Travis: my phrasing] are assigned and composed, ie. "learned", during "training" by having non-technical users directly manipulate the robot rather than programming it (which is also possible for those inclined). This gives the robot an air of common sense.

Safety Standards:

Travis: The press release also mentions "No need for cages." I know SEA's, force sensing, and the payload make the robot relatively safe (based on my experiences with Meka robots and the PR2). However, how do you handle existing safety regulations? I thought E-Stops, cages, and light curtains were required for industrial settings.

Rod: You're right. That whole space is in flux. Existing standards just aren't designed for these types of arms... they're too used to big, dangerous, position-controlled arms. Thankfully, factories can do their own safety analysis. We've already gone through this process, and the results are promising.

Furthermore, almost everyone in the industry is trying to revise the standards -- from Kuka, ABB, and Universal Robotics. It looks live everyone is aligned to make this happen, and things like ISO Standards for robot safety are moving in that direction

Why now?

Travis: I have my own take on this... but why now? What is special about right now that makes this possible compared to 10-15 years ago?

Rod: The usual suspects: a market need, inexpensive manufacturing, improved sensing, and the big one: computation. The computation is such that sensing (eg. vision, 3D, tracking) and kinematics (eg. gravity comp, force control, anti-collision planning) are much more feasible. The time is ripe for disruption.

[ Travis: Heh, Rod mentioned using the screen to assist with perception, eg. using it as a uniform, known background for visual segmentation. Cool idea! You could even flash a texture on the screen to do 3D imaging sans a range camera. Sorta like Grant Schindler's (Georgia Tech alum) "trimensional" app on the iPhone. ]

Intellectual Property

Travis: The Gill Pratt / Matt Williamson SEA patent is set to expire shortly (2015? It was filed in 1995 and issued in 1997). Are you worried about competitors (eg. Redwood Robotics) or knockoffs?

Rod: We've got an exclusive on the SEA patent, so we're not worried short-term. Plus, we've got several key patents in the pipeline (filed). We think we're pretty well covered. In any case, it's an exciting time for robotics.

Advice to Robotics Entrepreneurs

Travis: Do you have any advice to budding entrepreneurs? Rethink has raised something like $50 Million in VC funding and seems to be on the verge of success. What's your secret?

Rod: Here's the thing... If you had gone to any VC four years ago and pitched, say, an elder-care robot... they would've told you "you're crazy." Someone needs to prove that a super low-cost platform is possible first. Rethink is it. Now you can point to Rethink and say "see it's possible" and even build it (hopefully) using our arms. This should spawn a large number of companies using our arms in ways we never imagined -- perhaps bypassing the research labs entirely. Get out there and solve problems.

The Press Release

(Note: this is currently the unofficial version. I'll update it with the official one and a link when it's available.)