Vibration control of a two-link flexible robot arm

Analysis and experimentation are described for a two-link apparatus in which both members are very flexible. Attention is focused on endpoint position control for point-to-point movements, assuming a fixed reference frame for the base, with two rotary joints. Each link in instrumented with acceleration sensing and is driven by a separate motor equipped with velocity and position sensing. The control perspective adopted is to implement a two-stage control in which the vibration control problem for fine motion endpoint positioning is considered separately from the gross motion, large angle skew problem. In the first stage the control law shapes the actuator inputs for the large angle movement in such a way that minimal energy is injected into the flexible modes, while in the second phase an endpoint acceleration feedback scheme is employed in independent joint control for vibration suppression at the link endpoints