Observer based control of a brushed DC motor at very low speeds over controller area network: An application in astronomical telescopes

Speed control of a brushed DC motor is achieved using feedback from an incremental encoder. At very low speeds the estimated velocity from the encoder pulses exhibit errors due to quantization and temporal discontinuity. An observer is designed to estimate the speed between these discontinuities and provide feedback to the controller. The controller with observer feedback is first implemented on a DSAPCE Hardware-in-the-Loop platform for validation. It is then implemented on dedicated embedded controllers distributed over a controller area network and the performance at different speeds is compared. The scheme can be applied in astronomical telescopes operating at very low speeds where sensors, actuators and controllers are normally distributed.