IEEE Spectrum – Today, large suppliers and their large customers dominate industrial robotics. But almost any manufacturer can afford a Baxter (or two). In the United States alone, there are roughly 300 000 small and medium-size manufacturers, Brooks points out. So it’s not inconceivable that Rethink could make humanoid robots a normal part of the manufacturing process for businesses of all sizes. And by improving the efficiency of human employees, it could make making things in the industrialized world just as cost effective as making them in the developing world.
Baxter is unlike any other industrial robot. With two arms, each with seven axes of motion—or degrees of freedom, in robotic parlance—and a reach similar to that of a human, Baxter is designed to take over those simple, dumb, mindless tasks that humans hate to perform because they’re so, well, robotic. Whereas traditional industrial robots perform one specific task with superhuman speed and precision, Baxter is neither particularly fast nor particularly precise. But it excels at just about any job that involves picking stuff up and putting it down somewhere else while simultaneously adapting to changes in its environment, like a misplaced part or a conveyor belt that suddenly changes speed.
There are two other major barriers to the adoption of industrial robots that Rethink wants to overcome: ease of use and cost. As for the first, Baxter doesn’t rely on custom programming to perform new tasks. Once it’s wheeled into place and plugged into an ordinary power outlet, a person with no robotics experience can program a new task simply by moving Baxter’s arms around and following prompts on its user-friendly interface (which doubles as the robot’s face). And while a traditional two-armed robot, including sensors and programming, will typically set you back hundreds of thousands of dollars, Baxter costs just $22 000. To achieve that, Rethink designed the robot from scratch. Underneath Baxter’s plastic exterior lie thousands of ingeniously engineered parts and materials that enable the robot to do what it does for the cost of a midsize car.
Keeping Costs Down
As the complexity of the robot has increased, keeping the cost down has been a constant struggle. The engineers found creative ways to work with less expensive components, which often meant designing parts out of cheaper materials. (At one point they attempted to build the entire arm, including the gear systems, out of plastic, but that didn’t pan out.) And by working closely with local manufacturers, they were able to get the parts they needed more cheaply and without compromising quality.
Brooks picks up a set of gears and waves it around. A Pennsylvania shop made them, he says, using a metallurgical process involving pressed powdered metal, which ended up being only about a fifth of the cost of traditional gears. The robot has hundreds of parts like these, and so the savings add up. Rethink used this design-for-manufacturing approach for as many parts as possible, eventually procuring 75 percent of them in the United States—a fact that Baxter advertises with a big “Made in U.S.A.” sign stamped on its back.
The other way Rethink has cut costs is through software. By giving Baxter the ability to autonomously compensate for its own mechanical irregularities as well as changes in its environment, Rethink has been able to avoid having to use costly components. So Baxter may not have the most expensive motors or the stiffest bearings or the most precise gearing, but it doesn’t need those things. For example, backlash in the gears—the slack in teeth couplings that may cause motion loss and vibrations—can be modeled and then adjusted on the software side so that the arms move smoothly. And the robot can use cameras to improve the accuracy of its movements, explains Elaine Chen, vice president of product development. “You don’t need the robot to be able to go somewhere within 0.01-millimeter accuracy in order to pick something up,” she says, “because the robot is going to see it, get a fix on it, and then pick it up.”
This all gets to one of Baxter’s key features: compliance. A robot is said to be compliant when it’s not completely rigid and when it can sense and control the forces it applies to things. “If you want a robot that’s going to deal with an unstructured environment, it can’t be stiff,” says Matthew Williamson, Rethink’s director of technology development. “You need compliance.”
Photo: David Yellen for IEEE Spectrum
PROGRAM ME, PLEASE: Product manager Mike Bugda demonstrates how to program Baxter to perform a new task. He simply holds the arm by the cuff and moves it to the desired location. He tells the robot what to do using a knob and buttons.
Software, Third Party and Capability Upgrading
Rethink is offering: future potential, embodied in the promise of frequent software upgrades that will give Baxter the ability to perform entirely new tasks. Rosenberg puts it this way: “The day you buy the robot is the day that it’ll perform the least well. Over time, your investment will become more and more valuable because the software will become more and more valuable.”
To that end, the company is planning to release a software development kit, or SDK, next year that will let others delve into Baxter’s guts and modify its capabilities. There will also be a variety of third-party grippers for handling parts with different shapes. What’s more, Baxter is relying on open platforms. It currently runs Linux and ROS (short for robot operating system), a software platform that’s becoming increasingly popular within the robotics community. Rethink is now looking for people to develop a ROS-compatible SDK and is considering eventually supporting a completely open-source framework for Baxter.