Voltage compensation of a pulse-width-modulated servomechanism

摘要

A position-feedback-control servomechanism for shifting the transmission of a vehicle has both an adaptive proportional-integral-differential controller to compensate for manufacturing variations, etc, and a voltage-compensation system that senses the battery voltage and prevents the gain of a servomechanism drive motor from varying significantly when the battery voltage changes. The motor is preferably a permanent-magnet type to whose terminals the battery voltage is switched on and off. The switching is done by electronic switches that are under the control of a pulse-width-modulated signal. The width of the pulses of the pulse-width-modulated signal is controlled by both a closed-loop position-error signal and a signal derived from an open-loop measurement of the battery voltage.