Adaptive pulsing motor control for positioning system

A control method for a driven-element-positioning apparatus which includes a motor for causing the driven element to approach its presently desired destination and subsequent desired destination, and means for measuring the position of the driven element and determining whether it has overshot the presently desired destination, such method comprising the following steps;

• establishing a control value for the motor;
• actuating the motor in accordance with the control value;
• setting the initial control value to cause intentional overshoot of the driven element past the presently desired destination;
• automatically changing the control value each time the driven element overshoots the presently desired destination;
• and
• retaining the changed control value as the motor control value for destination-approach movements of the driven element both to its presently desired destination and to subsequent desired destinations.

For use with a positioning system for moving a driven element in response to command signal pulses precisely to a presently desired destination and also to subsequent desired destinations, which system includes (a) a motor which exerts moving force on the driven element whenever the motor is on, and which is on when the command signal is present and off when the command signal is absent;

• and (b) means for measuring the position of the driven element and comparing it to the presently desired destination;
• that method of controlling the motor which comprises the following steps:
• setting an initial distance of driven element travel which is sufficient to cause the latter to overshoot the presently desired destination;
• turning off the motor after the initially set distance has been traveled, and permitting the driven element to coast to a stop;
• measuring the distance by which the driven element has overshot the presently desired destination;
• determining a new, shorter distance of driven element travel which depends on the distance of overshoot;
• storing the new, shorter distance for future use as the initial travel distance toward subsequent desired destinations;
• determining another new, shorter travel distance if any stored initial travel distance causes the driven element to overshoot the then desired destination;
• and
• storing the latest new, shorter travel distance for future use as the initial travel distance toward subsequent desired dedstinations.

For use with a positioning system for moving a driven element in response to command signal pulses precisely to a presently desired destination and also to subsequent desired destinations, which system includes (a) a motor which exerts moving force on the driven element whenever the motor is on, and which is on when the command signal is absent;

• and (b) means for measuring the position of the driven element and comparing it to the presently desired destination;
• that method of controlling the motor which comprises the following steps:
• establishing an alternation of motor on and motor off periods;
• causing a cycle of interim target positions short of the presently desired destination to which the motor is to move the driven element;
• establishing an initial value of driving energy applied to the motor during its on periods, which value is normally sufficient to cause the driven element to overshoot the presently desired destination after one of its on periods;
• reducing by an incremental amount the initial value of driving energy applied to the motor during its on periods after each instance in which the driven element overshoots the presently desired destination;
• storing the new, reduced initial driving energy value for future use as the initial motor driving energy value toward subsequent desired destinations;
• and
• if the driven element overshoots the then desired destination during any future cycle of such interim target positions, establishing another new, incrementally reduced value of initial motor driving energy, and storing the latest new value for future use as the initial motor driving energy value toward subsequent desired destinations.

For use with a positioning system for moving a driven element precisely to a destination in response to command signal pulses, which system includes (a) a motor which exerts moving force on the driven element whenever the motor is on, and which is on when the command signal is present and off when the command signal is absent;

• and (b) means for measuring the position of the driven element and comparing it to the destination;
• that method of controlling the motor which comprises the following steps:
• establishing an alternation of motor on and motor off periods;
• setting an interim position goal for movement of the driven element by the motor;
• establishing a first value of driving energy applied to the motor during its on periods;
• applying the first value of driving energy to the motor;
• determining whether the interim position goal has been attained;
• if the interim position goal has not been attained, increasing the value of the driving energy by an incremental amount to constitute a second value;
• applying the second value of driving energy to the motor;
• continuing a series of incremental increases in the value of driving energy until the interim position goal has been attained;
• initially setting the first value of driving energy at a level which is normally sufficient to cause the driven element to overshoot the destination;
• if overshoot does occur, reducing by an incremental amount the first driving energy value of the series of incremental increases;
• storing the reduced first driving energy value for future use as the first value of each series;
• setting a new interim position goal for movement of the driven element by the motor;
• using the new, reduced first driving energy value to begin another series of incremental driving energy value increases until the new interim position goal has been attained;
• and
• if the driven element is caused to overshoot the destination by the first driving energy value of any series, reducing by a further incremental amount the first driving energy value of the series, and storing the latest new first driving energy value of the series for future use in that function.

For use with a positioning system for moving a driven element precisely to a destination in response to command signal pulses, which system includes (a) a motor which exerts moving force on the driven element whenever the motor is on, and which is on when the command signal is present and off when the command signal is absent;

• and (b) means for measuring the position of the driven element and comparing it to the destination;
• that method of controlling the motor which comprises the following steps:
• using equal successive clocked periods to provide consistent timing intervals;
• determining the distance traveled by the driven element during each successive timing interval, thereby providing a speed of travel measurement;
• causing the motor to turn off at certain target positions of the driven element;
• allowing the driven element to reach a desired reduced speed after each motor turn off, before initiating a subsequent control signal;
• and
• determining that the driven element has reached the desired reduced speed when the distance traveled by it during one of the successive timing intervals is at or below a predetermined fraction of the distance traveled by it during the earlier timing interval when the motor was turned off.

For use with a positioning system for moving a driven element precisely to a destination in response to command signal pulses, which system includes (a) a motor which exerts moving force on the driven element whenever the motor is on, and which is on when the command signal is present and off when the command signal is absent;

• and (b) means for measuring the position of the driven element and comparing it to the destination;
• an apparatus comprising:
• means for using equal successive clocked periods to provide consistent timing intervals;
• means for determining the distance traveled by the driven element during each successive timing interval, thereby providing a speed of travel measurement;
• means for causing the motor to turn off at certain target positions of the driven element;
• means for allowing the driven element to reach a desired reduced speed after each motor turn off, before initiating a subsequent control signal;
• and
• means for determining that the driven element has reached the desired reduced speed when the distance traveled by it during one of the successive timing intervals is at or below a predetermined fraction of the distance traveled by it during the earlier timing interval when the motor was turned off.