Hybrid hydrostatic transmission enables robots with human-like grace and precision

Hybrid hydrostatic transmission enables robots with human-like grace and precision
Credit: Disney Research

A new type of hydrostatic transmission that combines hydraulic and pneumatic lines can safely and precisely drive robot arms, giving them the delicacy necessary to pick up an egg without breaking it.

This transmission has almost no friction or play, offering extreme precision for tasks such as threading a sewing needle.

The hybrid transmission makes it possible to halve the number of bulky hydraulic lines that a fully hydraulic system would require. Robotic limbs can thus be made lighter and smaller, said John P. Whitney, an assistant professor of mechanical and industrial engineering at Northeastern University, who led the development of the transmission while an associate research scientist at Disney Research.

Whitney and colleagues from Disney Research, the Catholic University of America and Carnegie Mellon University, will report on the new transmission and the upper body humanoid they built with it at the IEEE Conference on Robotics and Automation, ICRA 2016, May 17 in Stockholm, Sweden.

"The transmission provides our robot with incredibly smooth and fast motion, while also allowing life-like interaction with people and the handling of delicate objects," said co-author Jessica Hodgins, vice president at Disney Research and a professor of robotics at Carnegie Mellon. "For now, the robot is remotely controlled by a human operator, but we would expect the same level of mechanical performance once the motions are automated."

Whitney said a robot joint normally would have two hydraulic cylinders, balanced against each other. But in this latest design, the researchers paired each water-filled cylinder with an air-filled cylinder instead. The pneumatic cylinder serves as a constant force air-spring, providing the necessary preload force, allowing the joint to move in both directions with only half the number of bulky hydraulic lines.

The researchers used the new transmission to build a simple humanoid robot with two arms, with stereo cameras mounted in the head, streaming their video signal to an operator wearing a head-mounted display. The arms are coupled to an identical control figure, hidden behind a wall to enable the robot to be used for human-robot interaction research.

"This technology enabled us to build that are light, fast, and dexterous," Whitney said. "They have an incredible life-like nature, offering a combination of small mass, high speed, and precise motion not seen before."

Robots using this technology are ideally suited for naturally compliant and life-like interaction with people. When tele-operated, the low friction and lack of play allow the to faithfully transmit contact forces to the operator, providing a high-fidelity remote sense of touch.

In addition to Whitney and Hodgins, the research team included John Mars of Disney Research, who developed the camera and head-mounted display system, and Tianyao Chen, a research assistant at The Catholic University of America, who designed the robot arms while an intern at Disney Research.

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More information: "A Hybrid Hydrostatic Transmission and Human – Safe Haptic Telepresence Robot-Paper" [PDF, 3.47 MB]
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May 12, 2016
And then there were so many robots that there was not enough people working to buy the robots. It's coming.

May 12, 2016
not enough people working to buy the robots
Have you heard about guaranteed minimum income in Switzerland and canada?

But there is no reason why robots cant pay taxes the same way human workers do now. It would be far easier. Robots have the capacity to report exactly how much work they do. They can report on materials and energy consumed, maintenance and storage required, and usage of infrastructure.

They can do this directly and be taxed immediately, thereby avoiding all the opportunities owners have to fudge and misreport. Eliminating humans from the tax collection process would automatically increase revenues enormously.

Emancipate the machines I say. Let them earn their own living and pay their own taxes. This is inevitable in some form or other, so we ought to start ASAP.

Construction machines will soon be transporting themselves to and from jobsites and working directly from construction docs and schedules. This might be an easy place to start.

May 12, 2016
Machines and people already pay taxes for merely existing. Property taxes in the former. Currency in the latter instead of using money.

May 17, 2016
The "gracefulness" of the system comes from the operator, not from the actuators. As you can see from the film, there's a person moving a mirrored actuator behind a screen.

The safety factor comes from the nearly 1:1 coupiling and force feedback between the input and output so the operator feels instantly what is going on at the robot. For longer distances or automated action, the end actuator would need to run under computer control via servos, and without additional feedback it would turn as insensitive as a brick.

The problem is that the input and output need a hydraulic line between them to transmit the force, and when the line gets longer you get slack, slop and lag, and resonant modes that make the end actuators wobbly due to the expansion and contraction of the tubes and the fluid inside.

May 17, 2016
But there is no reason why robots cant pay taxes

What sense would that make? Do you tax an apple peeler or a bread dough maker? Or a thermostat by how many times a day it clicks?

Emancipate the machines I say. Let them earn their own living and pay their own taxes.

Inanimate objects do not have a "living" and they do not own what they produce or indeed earn wages because they have no use for money, so there's no sensible semantics under which you could tax a robot.

Have you heard about guaranteed minimum income in Switzerland and canada?

Yes, and if such income is large enough to live comfortably on, it will be unsustainable and lead to a malthusian catastrophe. If not, it won't solve the problem.

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