Feedback Linearizing Controller for a Single Link Flexible Arm with a Passive Gravity Compensation Mechanism

Abstract

Despite the benefits that the spring based gravity compensation mechanism has brought to the field of rigid robotic manipulators, there have been no substantial efforts toward transferring these developments to the field of flexible link robotics. In this paper, we present an input state feedback linearization controller for the tip positioning of a flexible link arm with a gravity compensation system based on springs. The controller is implemented into a double loop control scheme, in which the inner loop addresses the motor position control in presence of joint friction, and the outer loop deals with vibration cancellation and the tracking of fourth-order trajectories for the tip position of the flexible arm. Taking into considerations the interacting forces between the flexible link and the gravity compensation mechanism, and also the characteristics of the control law, we propose a sensory system to measure all the relevant signals. The proposed controller is tested on an experimental prototype built in our laboratory.