Inferential control of DC motor using Kalman Filter

Permanent Magnet DC motors are useful in a range of applications in which speed of the motor is controlled by varying the voltage applied to the armature. Various feedback techniques such as voltage tachometers, optical encoders are used to sense the speed. However if the speed sensors are not available or may fail to indicate the speed, due to sensor failure, we can still use the armature current measurement to estimate the speed and hence prevent the performance of control loop from getting deteriorated. Such type of control obtained using estimates of primary variable from measurements of secondary variable is called as “Inferential Control”. In this paper we present a novel technique of controlling the speed of a motor from speed estimates obtained from armature current measurements using Kalman Filter and the estimated speed is used in place of actual speed measurements.