Advanced Nonswitching Discrete Time Sliding Mode Control for Speed Tracking of a DC Motor

In this article, a detailed analysis of fast output sampling (FOS)-based multirate output feedback (MROF) technique is done in the context of discrete time sliding mode control (DTSMC) based on nonswitching reaching law. In addition, for better performance and improved robustness, the relative degree of the sliding variable is chosen as two instead of one. Quantitative analysis of robustness in terms of ultimate band for the relative degree two (RD2) approach is done and compared with that of relative degree one (RD1) approach. First, only RD1 and RD2 approaches are proposed for speed tracking of a dc motor under parametric uncertainty. Then the same task is done using MROF-based RD1 and RD2 approaches. The proposed work is validated experimentally and is used for tracking a reference speed of a dc motor.