Leader–Follower Robot Arm with Force Feedback

Master–slave demo using direct-drive motors

1) Master–slave control

When the master (right) moves, the slave (left) follows with a delay of approximately 10 µs, reproducing the same motion.

Position input to the slave using the master’s encoder pulses.

2) Reaction-force detection and feedback

If an external force is applied to the slave, a reaction force is fed back to the master. (Example) When the slave axis pulls a rubber band, the master side can feel the increasing resistance as the band stretches.

Feed the position-error analog monitor output back to the master as an analog input.

3) Safety alarm function

When an external force exceeds the preset threshold on the slave side, an alarm is issued and the servo turns off to stop safely. This prevents strong-contact incidents at the slave axis and protects the motor from damage. Using a hollow-shaft direct-drive motor allows cables to pass through the shaft, enabling a compact robot design.