Experimental study on operator-based robust nonlinear vibration control for an L-shaped arm with unknown load

Abstract

A linear-motor-driven L-shaped arm experimental system is studied in this article. The arm with unknown load is driven by the motor and actuated by a piezoelectric actuator at the same time. This study aims to control the motor motion and the actuator’s behavior simultaneously, resulting in less arm vibration. First, the arm vibration relating to the load and the linear motor is modeled by considering it as an Euler–Bernoulli beam. Then, the control design for the arm and motor is proposed using the operator-based nonlinear control approach involving an on-line discrete wavelet transform. The operator-based right coprime factorization is used to ensure the system stable and robust. The discrete wavelet transform is utilized to remove the influences of some undesired disturbances and improve the operator-based control performance. In addition, the load mass is estimated using fast Fourier transform based on the discrete wavelet transform decomposed vibration signal. Finally, experiments are conducted comparing with the previous study, and the results show that the proposed control is effective to reduce the arm vibration in less time.