Sawyer: Rethink Robotics Unveils New Robot

Photo: Cassandra Zampini
"Need a hand?"

Earlier this week, we went up to Boston to see something new from Rethink Robotics. They wouldn’t tell us what (not even a hint), but we bought plane tickets anyway, because Rodney Brooks told us that it wasn’t just some slightly different version of Baxter. And it wasn’t: it’s a completely different robot, stuffing all of the adaptive, collaborative technology that makes Baxter unique into a form factor that’s smaller, faster, stronger, and more precise.

This is Sawyer.

“It became clear that we could do some things a lot better with a different sort of arm,” Rod Brooks told us.

He explained that Sawyer is designed primarily for machine tending, circuit board testing, and other precise, repetitive tasks, specifically those that take place in the middle of a long assembly line of electronics products. There’s a huge need for a robot that can do tasks like these, especially in Asia, and that’s the market Rethink is going after with Sawyer. “We’re moving into mass electronics manufacturing,” said Brooks.

The new robot has many things in common with Baxter, but there are also major differences. Just like Baxter, Sawyer is built around series elastic actuators that make it mechanically compliant. The actuators, however, have been redesigned: Baxter uses springs made out of “C”-shaped pieces of steel, whereas Sawyer uses springs made out of titanium in the shape of a symmetrical, curvaceous “S.” The spring redesign (and running cables through the joints) allowed Sawyer’s arm to be made considerably smaller. Brooks said the arm’s seven degrees of freedom and 1-meter reach open up new possibilities for machine tending that Baxter is just too bulky for. “The arm can just snake right in there,” he said.

The improvements come at a price. The one-armed Sawyer costs a bit more than its two-armed predecessor, at US $29,000. (Baxter is listed at $22,000.)

“Baxter has done really well in certain kinds of tasks, like taking stuff off a line, or packing boxes,” said Rethink chief marketing officer Jim Lawton. “The feedback we’ve gotten from customers has been, ‘We want to do more stuff the way Baxter does stuff, but we want to do it in other kinds of tasks.’ And those other kinds of tasks require a robot to be able to perform a little bit differently.”

Rethink has integrated a hockey puck-style Harmonic Drive into each of Sawyer’s joints to help eliminate backlash. That, plus a slight overall stiffening, has made the robot faster and more precise than Baxter, although Rethink isn’t ready for numbers on things like repeatability. “Substantially better than Baxter” is all Lawton would say.

Some specs:

  • Weight: 19 kg (42 lbs)
  • Payload: 4 kg (8.8 lb) 
  • Reach: 7 degrees of freedom and 1-meter reach 
  • Actuation: Series elastic actuator and Harmonic Drive, with optical encoder
  • Repeatability: N/A
  • Force sensing: High-resolution force sensing embedded at each joint
  • Vision: Camera in the head for wide field of view and Cognex camera with built-in light source in the wrist for precision vision applications
  • Software: Intera, with software updates every 4 months
  • Body: Sealed against dust and spray [Baxter isn’t]
  • Expected lifetime: 30,000 hours
  • Price: US $29,000 (available in North America, Europe, China, and Japan)

According to Rethink, labor costs in Chinese factories are rising 15 to 20 percent every year, and it’s routine for them to see turnover rates of 25 percent per month or worse. There are hundreds of thousands of these jobs that people don’t want to be doing, but that have been resistant to automation because they require fast ROI, ease of use, and flexibility. Those are capabilities that Baxter has brought to manufacturing, and what Sawyer is prepared to bring to electronics assembly and testing.

Lawton noted that the new robot can be installed in spaces that Baxter couldn’t. Sawyer fits into a 2 x 2 x 5 feet volume, which he said is small enough to replace a human on a tightly packed electronics assembly line (try to do that with Baxter!).

Sawyer has a limited number of sensors; in talking with clients about potential applications, Rethink decided to focus on what would be most useful. The biggest upgrade is the wrist camera, which is now a Cognex with a built-in light source, repositioned so that it won’t be occluded by large grippers.

Other than that, there’s just one more camera on Sawyer’s head. And of course all of the series elastic actuators can sense forces very accurately. This allows the robot to do more delicate tasks when it manipulates and interacts with objects and the environment, and also gives Sawyer the level of intrinsic safety that made Baxter a robot that humans could work around, even if it accidentally slams on them.

Sawyer runs Rethink’s ROS-based software platform Intera and features the same interactive control system as Baxter, with just a few tweaks to the interface. You can still teach the robot to do simple tasks just by grabbing it by the wrist and showing it once, and it’ll adapt to minor changes in its environment without any additional input.

Lawton said Rethink has “signed contracts for hundreds of robots” already. For the record, “hundreds” is also the number of Baxters that have currently been sold into manufacturing. (By comparison, Universal Robots, one of Rethink’s main competitors, has sold 4,000 robotic arms and plans to sell just as many this year, including a new, smaller model, the UR3.)

Unlike Baxter, Sawyer was intended from the very beginning to be sold to clients internationally. It will be initially available in North America, Europe, China, and Japan, starting this summer.

Not surprisingly, Brooks is very proud of the newest family addition. “It’s just a gorgeous robot,” he said.

[ Rethink Robotics ]

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