Patent ID: 6809488
Filing Date: 2004-10-26
Classification: E05F,E05Y,G05B,H02H,H02P,Y02P

Abstract:
A method for determining the position of an element drivable by a motor within a predetermined segment of travel between first and second block positions, the method comprising:energizing the motor to drive the element along the predetermined segment of travel, the element having a given amount of kinetic energy as the motor drives the element alone the predetermined segment of travel; counting current ripples contained in an armature current signal of an armature of the motor as the motor drives the element alone the predetermined segment of travel; determining the position of the element along the predetermined segment of travel as a function of the counted current ripples; if the motor is to drive the element into the first block position once the element is within a certain distance of the first block position, de-energizing the motor for a predetermined period of time in order to reduce the given amount of kinetic energy of the element to a reduced amount of kinetic energy; re-energizing the motor after the motor has been de-energized for the predetermined period of time in order to drive the element into the first block position such that while being driven by the motor into the first block position the element has more than the reduced amount of kinetic energy but less than the given amount of kinetic energy; and setting the counted current ripples to a reset value after the element has been driven by the motor into the first block position and prior to the element being driven by the motor out of the first block position such that the reset value corresponds to the first block position.