Method for stepper motor position referencing
AssigneeTexas Instruments Incorporated
InventorEric P. Best
Life of this patent
Estimating the term…
Abstract
A method for referencing a polyphase stepper motor by monitoring the current step response in at least one driven phase is presented. The coil current step response is compared to past step responses in order to determine when an increase in or maximum load is present. A combination of step to step variance, step response variance from mean current magnitude, and average current magnitude variance, as well as other measures can be combined to create an algorithm output. The output is compared to a pre-determined threshold and if the value is greater than the threshold, the motor is commanded to halt its position, which remains magnetically synchronous. This position is then used as a reference point to zero, or to home the motor.
Claims11
A method of referencing a stepper motor to a mechanical hard stop comprising the steps of:
- measuring the motor coil electrical current step response in each driven phase;
- and
- comparing motor coil electrical current step response for a current driven phase with a statistical measure of motor coil electrical current step responses for prior driven phases;
- and
- determining the stepper motor has reached a reference position at a hard stop when variation said electrical current step response relative to said statistical measure of prior motor coil electrical current step responses meet a predetermined criteria.
Dependencies are inferred from the claim text.