Identification and control of a single-link flexible manipulator

Abstract

Model identification and control of a single-link, very flexible manipulator is carried out. The objective is first to find the transfer functions relating the tip position to the motor position and the motor position to the motor current, and then to use the transfer functions to control the tip position of the manipulator. Because of the nonlinearities introduced by the static friction of the motor and due to very low damping of the manipulator, classical frequency-domain techniques cannot be used to find the transfer functions, so a novel method is proposed. A set of experiments has been performed, and transfer functions which fit this data have been obtained. The control scheme contains an inner loop for the motor position and an outer loop for the tip position. For the outside loop, feedforward control and the computed torque techniques are evaluated.