Combined Sensor–Sensorless Control of PMDC Motor for HD Camera of Unmanned Monitoring System

Abstract

This paper presents a position control scheme for a high-definition serial digital interface (HD-SDI) camera of an unmanned monitoring system. A combination of both sensor and sensorless algorithms of a permanent magnet (PM) DC motor is proposed to create smooth camera movements, stop it at desired positions, and obtain high-quality images without shaking. The back EMF of the motor can be estimated and its actual speed can be calculated accurately by using a model reference adaptive sensorless (MRAS) method. A low-resolution hall sensor is used to approximate the speed instead of measuring the actual value. The moving position can be estimated from the speed approximation and it can be used together with a sliding mode observer to modify the back EMF constant. In the advanced position control of the camera, both instantaneous speed and moving position references are determined by the acceleration and deceleration speed patterns to satisfy the dynamic response during operation. Furthermore, the instantaneous position error can be compensated by incorporating a speed reference. The effectiveness of the proposed control scheme was verified through experiments.