Step-out detection and error compensation for a micro-stepper motor using current feedback

We propose a method to detect step-outs for a micro-stepper motor and a way to compensate the missing steps to maintain appropriate operation. Coil currents and their behaviors are investigated to determine the onset and termination of a step-out. Exact step-out values are identified, and a corresponding compensation scheme is proposed. Even though the use of an encoder to measure position error provides a means of compensating for the error, the primary cause of the error due to the step-outs may not be clearly identified. Rather, the coil current feedback is used in place of encoder measurements, we can clearly determine amount of the step-outs which results in the position error compensation.