Self-adjusting homing for a stepping motor

Abstract

For step motors positioned in response to an external reference location, correction for potential one step misalignment is provided. The method and the apparatus of the invention provide a read/write memory, for storing therein a phase state of the step motor at a particular location, e.g. a home position. The home position may coincide with the external reference location or may be offset therefrom by some predetermined move of the step motor. During cold starts, where memory is not retained, the step motor is moved to its home position and then the phase state of the machine is saved. On subsequent warm starts, after the step motor is moved to the assumed home position, the step motor is controlled to assume the phase state that has been previously stored.

Dependencies are inferred from the claim text.