Adaptive Dynamic Surface Control of a Flexible Robot Based on the K-State Observer

摘要

The flexible manipulator is a complex electromechanical nonlinear system with a rigid flexible coupling, and its control performance is affected by many factors, such as inaccurate modelling and measurement, load variation, and uncertainty of external disturbance. In view of improving the effect of time-varying model parameters and external disturbances on the performance of the control system, an adaptive dynamic surface control method of the flexible manipulator based on K-state observer was proposed in this study. On the basis of the analysed characteristics of the flexible manipulator system model, a K-state observer had been constructed when the system state was not completely measurable. Then, an adaptive dynamic surface control method was designed by taking the position and speed of the flexible manipulator as the control objective. Finally, the effectiveness of the control method was verified by simulation. Results show that, when no model parameter uncertainty exists in the system, the dynamic surface control has a higher tracking accuracy than the inversion control, the maximum tracking error of angular velocity is reduced by 1.3 times, and the steady-state control input is reduced by 550 times. When the system has model parameters but only the joint angle position can be measured, the conventional inversion control and dynamic surface control cannot achieve system control. The adaptive dynamic surface control can achieve high-precision system tracking at 2.5 s, and the state and parameter estimation of the system can achieve online observation at 4 s and 2.5 s, respectively; and the adaptive dynamic surface control in the steady-state control input can reach 1/18. The proposed method can provide a reference for a flexible robot to achieve high-precision tracking in a complex assembly environment.