Position control of linear permanent magnet BLDC servo using iterative learning control

Linear brushless direct current servo motors (LBLDCM) are widely used for high performance position control applications. Conventional proportional-integral-derivative (PID) position controller provides satisfactory performance for set-point position regulation. However with the presence of nonlinearities and uncertainties in the drive system, linear PID controller is not sufficient to provide satisfactory time-varying trajectory position tracking control. In order to improve the tracking performance for periodic time-varying trajectory, we propose a hybrid control scheme consisting of a linear conventional PID position controller together with a plug-in iterative learning control (ILC). The proposed controller is implemented on a general-purpose DSP DS1104 controller board from dSPACE to drive a 300 mm stroke length, DX20-C4 LBLDCM. Experimental results obtained demonstrate the improved tracking performance of the proposed hybrid controller.