UNDERHAND day 46 · how much elbow does handwriting need?
shoulder motor 20 N·m · carriage 0.25 m/s · elbow budget:
With no elbow motor the forearm can only pull the pen along its own length, so at writing speed the pen hangs under the elbow and every stroke is an arc around the carriage. Letters come out as loops. The optimizer had 1200 iterations and a differentiable simulator. This is the best it found.