Adaptive Control of a Flexible Manipulator with Varying Payload

Abstract

This research is concerned with the control of the tip position of a flexible manipulator carrying variable payload. The tip of the manipulator considered here has three degrees of freedom, viz, one rotational and two translational. The desired rotational motion is the result of a command whereas the undesired translational motions are due to the deflection caused by the payload. Lagrangian equations with assumed mode shape functions are used to derive the dynamic equations of the manipulator. A recursive least square algorithm was used to identify the parameters. Numerical problems of the algorithm were overcome by introducing a scale factor and a time varying forgetting factor. The self-tuning adaptive control algorithm scheme was successfully implemented to control the rotational motion of the tip of the flexible manipulator carrying varying payloads. For the remaining two translational motions, the PID control algorithms were developed and fine tuned. The overall simulation results demonstrated the ability of the developed control system to maneuver the flexible manipulator so that the tip reaches the target position accurately under varying payloads.