Robust Sliding Mode Control for a DC Motor with Low Resolution Encoder

In numerous industrial applications, electric motors are employed as actuators. A closed-loop control can be simply implemented by the use of optical or magnetic encoders, that are usually significant cost in the control system. In this paper a Robust Sliding Mode Control method was applied on a DC motor with a cheap, low resolution encoder. The coarse position measurement of the encoder was compensated using a Least Squares Fit position and velocity estimator. In the proposed scheme the position estimation was improved by combining real measurements with virtually augmented points, through which a 2
^nd
order polynomial was fitted in a Least Squares manner. The proposed method was successfully tested on experimental basis.