Cross-Coupled Synchronous Control of Dual-Linear Motor Servo System Based on Disturbance-Assignment Observer and Iterative Learning Control

In this article, an easy-to-implement cross-coupled synchronous control for dual linear-motors servo system based on disturbance-assignment sliding mode observer (DASMO) and iterative learning control (ILC) is proposed to solve the problems of the loss of internal forces and synchronous control in this system. First, the stress source of the crossbeam is analyzed, and the comprehensive error is defined under the cross-coupled control (CCC). Then, a controller based on super-twisting algorithm (STA) is designed under the CCC to reduce the synchronous error of dual-axis motors. Considering that the operating conditions are performed in periodic operation, ILC is introduced to compensate the tracking error of single-axis motor. Furthermore, to improve the precision of synchronous control under load, a disturbance observer with the strategy of disturbance-assignment is designed. Compared with the traditional double sliding mode disturbance observers (DSMOs), its implementation is simpler, and the reduction of synchronous error is more obvious when the load is unbalanced. In the design of the controller, the tuning of the parameters is easy to implement. Finally, the precision of synchronous control and less loss of internal force are verified by experiments at different load positions, which prove the effectiveness of the control strategy.