Experimental study on PDS force control of a flexible arm considering bending and torsional deformation

This paper describes the Lyapunov-based force control suppressing the coupled bending and torsional vibrations of a one-link flexible arm with a rigid tip body. On the basis of the distributed parameter model, the output feedback control law is constructed using Lyapunov method, and the asymptotic stability of the closed-loop system is proved on the basis of the invariance principle. The constructed control law consists of the PD feedback of the motor angle, a feedback of the bending strain at the root of the flexible arm, and the feedforward of the desired bending moment torque to achieve the desired force control, which is called PDS force control. Some experiments are performed to show the effectiveness of the proposed controller. From the results, it is found that the bending strain feedback is effective for not only bending vibration absorption but also torsional vibration absorption.