Digitally controlled sliding mode based servo-system with active disturbance estimator

This paper considers the design of robust servo system for accurate tracking of complex referent signals in the presence of internal and external disturbances. Discrete-time sliding mode tracking controller is employed in servo-system design. In order to improve tracking accuracy, application of active disturbance estimator is suggested. The same sliding mode controller, designed for reference tracking of nominal system, is identically implemented in the control subsystem within the estimator. The overall servo-system exhibits high tracking accuracy under action of parameter uncertainties and external disturbances. Experimental results confirm the effectiveness of the proposed servo-system structure.