My next step in getting fluent with encoders and closed-loop control. The idea: control one arm (the "leader") manually by hand, read its joint angles with encoders, and have a second arm (the "follower") mirror that motion in real time via stepper motors.

The core control loop is proven out: encoder input rotations map to commanded stepper rotations, so turning the input shaft drives the motor to match (video below). Right now that's a single-axis proof of concept on the bench; the CAD for the actual leader/follower arm pair is next on the list.