Models for PIM digital redesign of a stepping motor current regulator

A current regulator in an analog driver for a stepping motor is converted into a digital driver using the so-called plant-input-mapping (PIM) method, with the integral action in the analog controller taken into account. Since the PIM design is model-based, plant models are obtained, their efficacies evaluated, and the robustness of the resulting digital controller to plant uncertainties assessed, experimentally. The performance of the proposed digital driver is found to be very close to that of the analog driver using a very low sample rate of 4 kHz, which enables mass production and with which the conventional Tustin´s method fails to provide good performances.