That is super awesome and even more awesome when I read that those are direct drive motors. All the compliance is done in software. This is something I must spend some time playing with. That advent of these small brushless motors with insane amounts of torque makes all sort of things possible that weren't before.
It's the direct drive motors that make it work. As someone from GE said a century ago, "You can't strip the teeth of a magnetic field". Direct drive robot arms have been built; Adept SCARA arms were direct drive. But they used to be too heavy for mobile robots.
What makes direct drive motors work are today's really good power FETs. You can do things with FETs, capacitors, and switching power supplies to get whatever voltage and current you need, at least briefly. Motors can be overloaded by huge amounts if you monitor the temperature, and you can build up a charge in supercapacitors for the next time you need to hit the motor really hard. Putting a computer in charge of a power supply is normal today, and may even reduce the parts count.
This, and Schaft, probably spells the end of Boston Dynamics' hydraulic monsters. That approach is just too bulky for anything below mule size.
Linear motors are a lousy business. They're almost all custom, while rotary motors are standardized. Prices seem to start around 10x the price of a comparable rotary motor. Find a market for a million identical ones and the price will come way down.
Some nice linear motors.[1] Even used on eBay, they're expensive.
Is a typical example. The same gyro/accelerometer/compass 6 or 9 dof sensors from phones that the quadcopter controllers themselves use, but re-purposed into keeping the camera stable. They're really fast.
I imagine that this stuff will be great for prototyping algorithms and figuring out good applications/requirements, but eventually (like when stuff has to be mass-produced) you'll see physical structures coming back in.
Either gearwork or biologically-inspired designs, replacing some flexible electric rules and brawn with structures that have rules and brawn "baked in".
Sort of like how your knees aren't "soft-coded" for a particular set of angles, it's an emergent property of a system shaped by a particular use.
The Issus genus of jumping insects (planthoppers)[0] have a gear mechanism connecting their rear legs. The gear synchronizes the motion of the two back legs; thereby reducing 'yaw rotation' when jumping[1]. The gear communicates motion faster than a purely neurological system.
I imagine that this stuff will be great for prototyping algorithms and figuring out good applications/requirements, but eventually (like when stuff has to be mass-produced) you'll see physical structures coming back in.
I don't know about that.
This platform can be fairly cheap in mass production. The legs are really cheap. No gears. And just two motors per leg. No extra force sensors, just the control electronics.
But if you added (say) a spring into the linkages, the rest-position could be tuned mechanically to be more energy efficient (e.g: zero power). The effect of the spring could be backed out in software.
But it's not until people have played with the use-cases, etc, that one really needs to think about efficiency in terms of battery life.
But if you added (say) a spring into the linkages, the rest-position could be tuned mechanically to be more energy efficient (e.g: zero power).
That might help with one particular gait, but I think it wouldn't give as much benefit for a system as flexible as this, which can run, hop, trot, and more.
And the spring itself would need to be modeled, and would make the position and force measurements less sensitive. That's why I don't think it would be a net win.
