Method of controlling an automotive mirror
AssigneeDelco Electronics Corporation
InventorJohn Thomas Pimley
Life of this patent
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Abstract
A mirror motor is coupled to the mirror by a ratchet coupling. A feedback signal representing the drive current of the mirror motor is digitally sampled and analyzed by a type of Fourier transform, preferably a discrete cosine transform, to determine the low frequency components of a current pulse which arises when the mirror reaches a stop at its end of travel and the ratchet operation begins to occur. A fundamental component is due to the pulse rise. Motor current is terminated if that component exceeds a threshold for a set time. A harmonic component is due to the ratchet action and pulse fall. Motor current is terminated if the harmonic element reaches another threshold.
Claims5
In an automotive mirror assembly including a motor for moving a mirror through a range bounded by limits in response to switch actuation and a ratchet coupling to permit the motor to continue operating when the mirror reaches a limit whereby current to the motor increases when a limit is reached and then decreases when a ratchet event occurs to thereby define a current pulse, a method of stopping current to the mirror when such a limit is reached comprising the steps of:
- developing a feedback signal corresponding to motor current;
- analyzing the feedback signal for a low frequency component wherein the amplitude of the low frequency component increases when the current pulse occurs;
- and
- stopping motor operation when the low frequency component exceeds a threshold value.
Dependencies are inferred from the claim text.