Calibrating stepper motor by driving fractional ranges

A method for calibrating a stepper motor that drives a driven member over a travel range having a travel limit, wherein the stepper motor can move the driven member to an operational point within the travel range, the method comprising:

• commanding the stepper motor to move the driven member over a travel distance from the operational point to the travel limit and doing so through a plurality of periods of continuous movement, wherein the plurality of periods of continuous movement become shorter as the driven member approaches the travel limit;
• commanding the stepper motor to stop the driven member between the plurality of periods of continuous movement;
• and
• defining a reference point upon the driven member having reached the travel limit following the plurality of periods of continuous movement.

A method of calibrating a stepper motor wherein the motor has a characteristic number of positions before a motor position cycle is repeated and wherein the motor moves a device over a known range of steps, the method comprising the steps of:

• initializing a calibration interval to be greater than the known range of steps;
• setting a next step value equal to ((1/number of positions)*calibration interval);
• driving the motor a number of steps equal to the next step value;
• determining if the calibration interval is less than a stop value;
• if yes, commencing a stopping sequence;
• or if no, modifying the calibration interval to equal (((number of positions−1)/number of positions)*calibration interval), and returning to the setting step.

A system for calibrating a stepper motor, the system comprising:

• a stepper motor wherein the motor has a characteristic number of positions before a motor position cycle is repeated and wherein the motor moves a device over a known range of steps;
• and
• a controller operatively connected to and commanding the stepper motor, the controller initializing a calibration interval to be greater than the known range of steps;
• setting a next step value equal to ((1/number of positions)*calibration interval);
• driving the motor a number of steps equal to the next step value;
• determining if the calibration interval is less than a stop value;
• if yes, commencing a stopping sequence;
• or if no, modifying the calibration interval to equal (((number of positions−1)/number of positions)*calibration interval), and returning to the setting step.