Iterative learning based sliding-mode position controller for linear permanent magnet brushless DC servo motors

In this paper, we propose a robust nonlinear sliding mode controller (SMC) for position control of the linear brushless direct current motor (LBLDCM). Being a nonlinear controller SMC exhibits improved tracking performance compared to the linear PID controller. For periodic position tracking, the tracking performance can be further improved by supplementing a plug-in iterative learning control (ILC) to the SMC. The experimental test results obtained from a 300 mm stroke length, DX20-C4 LBLDCM validates that the nonlinear SMC controller improves the tracking performance by a factor of 10 in comparison with the linear PID controller. Further inclusion of the plug-in ILC, the tracking performance is even improved by another factor of 2. This shows the efficacy of the proposed hybrid position controller.