[Animats]

cooling

I was wondering about that. The big innovation from Schaft was that they liquid-cooled their motors. That allowed them to build a full size humanoid without going hydraulic.

What happened that made electric motors so much better since the 90’s? It’s not like we made groundbreaking discoveries about magnetism, right?

Neodymium-cobalt magnets and 3-phase drive in small packages. Also, a big market for high-power low-weight drone motors brought the price down.

http://moticont.com/direct-drive-linear-motors.htm

That's a nice little device. Those might make good finger actuators.

Linear motors have long been a tiny niche. I'd looked at Aura linear motors, which was the leading brand back in the 1990s, but Aura got themselves into serious legal trouble. They're back now, but mostly as an aerospace supplier. Power to weight ratio in small linear motors has seldom been good. It's not clear whether this is fundamental or just lack of engineering effort due to small demand.