Tip-position/velocity Tracking Control of Manipulator for Hull Derusting and Spray Painting based on Active Disturbance Rejection Control

Abstract

During sandblasting and spray painting for hull, the tracking performance of the end-effector of manipulator to the outer surface of the hull in uniform velocity is seriously affected by uncertainty of the electrohydraulic actuator and deflection of the manipulator. To effectively improve the tracking performance of the tip-position/velocity, a novel tracking control strategy is proposed, which is based on active disturbance rejection control (ADRC) with extended state observer (ESO) and setting position feedforward control with deflection compensation. First, to reduce tracking error caused by the deflection, the reference positions of two cylinders driving telescopic and luffing motion are calculated with consideration of the deflection influence according to manipulator geometry. And then, ADRC technique is adopted to design the position servo controller of the luffing/telescopic cylinder with the help of the estimate for the uncertainty of the electro-hydraulic system by the ESO. The stability of the whole closed-loop system and the convergence of tracking error are guaranteed theoretically, simultaneously, simulation carried out in Matlab/Simulink environment with physical parameters of a real system demonstrates the effectiveness and superiority of the proposed control strategy compared with existing control schemes. Furthermore, the experimental result is given to show the feasibility and availability of the control method.