On combining slewing and vibration control in flexible manipulators via singular perturbations

The problem of designing a composite control as a strategy for controlling flexible link manipulators is addressed. The composite control consists of a slew control based on the reduced order model to achieve the desired slewing of the robot links and a fast control based on a manifold condition whose purpose is to dampen the link vibrations. The slow control is a decentralized torque control which approximately linearizes the reduced order model and adds a PI (proportional integral) control term for trajectory tracking. The fast control is a distributed actuator which consists of a thin piezoelectrically active film that when applied with a voltage produces a strain that dampens flexural vibrations. The control design is based upon a distributed parameter model of a two-link flexible manipulator. Computer results using a finite dimensional model obtained via modal expansion are presented to illustrate the control strategy