Nonlinear Control of a Two-Link Flexible Manipulator Based on Three-Step Method

For the control performance of a flexible two-link manipulator is susceptible to elastic oscillation, a three-step non-linear control strategy is presented to track the desired trajectory at the end of the manipulator and reject the oscillation of the link. First, the whole manipulator is considered as two independent subsystems and the oscillation is considered as a disturbance of the system. Then, a three-step control law is deduced for the subsystem, including the steady-state-like control law, the reference dynamic feedforward control law and the error feedback control law, which constitute the general control law with the typical structure of PID and make the disturbance (oscillation) is compensated. Finally, the scheme is validated on the platform of Quanser flexible manipulator. The experimental results show that the proposed nonlinear control method has good track tracking effect and oscillation suppression performance under several different sets of reference input signals.