3 ms·

does anyone understand why we have 4 drive motors for 3 degrees of freedom? it didn't seem that way from the presentation but maybe the motor axes aren't aligne

• jbay808 5y ago
  Two of the motors have to be synchronized together, because there are certain angles where either one or the other lose any torque transmission.
• zardo 5y ago
  It eliminates gimbal lock
  • Animats 5y ago
    No, it doesn't. Watch the video out to the end, and you'll see what happens as you go through a pole. This isn't a homogeneous system; there's a moment when the gear flips.
    • jbay808 5y ago
      That's an accident of the trajectory chosen for the animation. The system doesn't have a kinematic singularity from input to output, just from output to input. Instead it has a zero from input to output, which is why it needs an otherwise redundant motor. To elaborate, there's one point where spinning an input motor doesn't rotate the output. When they reverse-generated the input trajectory from the output trajectory, that point has no unique solution; spinning the input motor has no effect on the output so the input can do whatever it wants. The animator let the input do a sudden backflip, but it didn't have to; that motion was not required and had no effect. It was probably just the output of a matlab script or something.