Position control of a two-link flexible manipulator featuring piezoelectric actuators and sensors

This paper presents a hybrid actuator scheme to actively control the end-po int position of a two-link flexible manipulator. A highly nonlinear system model including inertial effect is established using Lagrange's equation as sociated with assumed mode method. Control scheme consists of four actuator s; two servo-motors at the hubs and two piezoceramics attached to the surfa ces of the flexible links. Two sliding hyperplanes which have time-varying parameters are designed for two servo-motors. The surface gradients of the hyperplanes are determined by pole assignment technique to guarantee the st ability on the hyperplanes themselves. The sliding mode controllers corresp onding to the hyperplanes are then synthesized on the basis of an equivalen t rigid-link dynamics to the proposed flexible manipulator. During the moti on, undesirable oscillations caused by the torques based on the rigid-link dynamics are actively suppressed by applying feedback control voltages to t he piezoceramic actuators. Consequently, the desired end-point motion is ac hieved. In order to demonstrate the effectiveness of the proposed methodolo gy both regulating and tracking control responses are evaluated through exp erimental realization. (C) 2001 Published by Elsevier Science Ltd.