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Toyota Reveals A Humanoid Robot That Can Run
Peter writes "Toyota researchers have unveiled a new humanoid robot that can run at 7 km/h, which is faster than Honda's humanoid robot ASIMO. Toyota's robot can also keep itself balanced when pushed, as shown in the video."
It looks to me like their is something below the foot that makes contact before the white part of the foot makes contact. From the high speed camera, it looks like this make contact on the front foot before the back foot leaves the ground. I thought to be running, both feet need to be in the air at once. Otherwise you were walking. Maybe I am just seeing the video wrong? Regardless, it looks very impressive.
It's about 4.4 MPH, or perhaps more usefully, a 13 minute, 40 second mile. Even us lazy nerds should be able to out-run that.
Why are all of these robots configured to work in a squatting position?
* lower center of balance
* better shock absorption
* "neutral" position more centered in range of motion
Humans don't walk that way because we have very long (and weak) legs relative to our body size and we'd exert too much energy keeping our muscles tense. But most other animals keep their legs in a "crouched" position all the time. Examine some skeletons.
How can I believe you when you tell me what I don't want to hear?
To run smoothly and efficiently robots will need joint motors that are springy and compliant just like human muscles.
I tend to agree. What you want to emulate a muscle is a spring with a variable spring constant and zero position. There are several ways to do that. A double-ended pneumatic cylinder can do it; if you pressurize both ends at a high pressure, it's stiff, and if you pressurize both ends at low pressure, it's springy. Relative differences in pressure change the zero position. If the valves are close to the cylinder, position control of pneumatic cylinders works. Someone at CWRU built a robot this way. Of course, you need an onboard air compressor.
There's a new variation on this concept - a device which is both a pneumatic cylinder and a linear motor. A pneumatic cylinder is a piston in a tube, and a linear motor is a magnet in a tube with coils outside the tube. So a device can be built which has a magnet as the piston and coils outside the tube, allowing both pneumatic and electrical operation. The linear motor does the fine positioning and the pneumatic system provides high power when needed.
It's possible to do an adjustable spring mechanically, using two actuators pulling on opposed springs. That's been tried, but most of the designs involve pulleys and strings, which tend to be troublesome. I've been working on a new string-less mechanical design in that area, one that can fit inside the space required for an R/C servo of the type used on hobbyist robots.
BigDog is hydraulic, and its actuators are very stiff. They had to put a bicycle shock absorber at the end of each leg to handle the landing shocks. But BigDog doesn't recover significant running energy. The Legged Squad Support System, the militarized successor to BigDog, may have energy recovery. There are things one can do with hydraulic accumulators and extra valves to get spring-like behavior out of hydraulics. Still, BigDog does a nice job; energy recovery will improve gas mileage, not stability.
There's also a way to fake spring-like behavior, using a "series elastic actuator". This is a leadscrew-type linear actuator in series with a stiff spring. When the spring is compressed, the drive motor frantically tries to release the pressure before the spring bottoms out. This doesn't really store much energy, but it can be used to fake something that does. Pratt at MIT came up with this, and it's a useful research tool.
There have been a number of other, more exotic muscle-line actuators, including fluids that change properties in an electric field, but so far, they're all worse than the ones mentioned above.