Comment by direwolf20
7 hours ago
Some types of motors don't require permanent magnets. If we need more motors than we can make permanent magnets, we'll adapt, perhaps with an efficiency loss.
7 hours ago
Some types of motors don't require permanent magnets. If we need more motors than we can make permanent magnets, we'll adapt, perhaps with an efficiency loss.
Motors with permanent magnets are preferred because they are much more cost- and energy-efficient, even with the painful reliance on REEs. There is a very strong incentive to find alternatives but nothing comparable has been found yet.
There are of course non-electric alternatives like hyrdaulic and pneumatic actuators but they are mostly good for power, not dexterity. The size and complicated fluid dynamics simply are not conducive for fine motor control. I do think these will play a large part eventually because even electric motors cannot economically produce enough force to be practically useful. Like, last I checked, the base-level Unitree robots can lift 2kg or so? Not even enough to lift a load of laundry.
At this point I suspect we'll end up with hydraulics for strength (arms, legs, torso) and electrics for dexterity (grippers)