High precision position control of PMSLM using adaptive sliding-mode approach

In this paper, a novel robust adaptive sliding-mode control scheme is presented high precision position control for a permanent magnet synchronous linear motor (PMSLM) servo system under the influence of unknown parameters, nonlinear friction, cogging forces, and external distance. The proposed strategy effectively combines the design techniques of adaptive control and sliding-mode control. In contrast to existing control approach, such as proportionalintegral-derivative (PID) control and adaptive robust control (ARC), the developed robust adaptive sliding-mode control not only has better tracking performance, but also provides stronger robustness. Moreover, in the ARC, the selection of robust control gain must meet certain conditions, and an observer is needed to estimate the unmeasurable states in the LuGre friction model, which makes the controller more complicated to realize. The system's stability is proved via Lyapunov stable theory. Finally, the effectiveness of the presented algorithm is demonstrated by numerical simulation for different situations.