Robust adaptive identification for sandwich systems with unknown time-delay

A discrete time, robust adaptive estimator is developed to identify the time-delay and sandwich systems parameters. To obtain explicitly the expression of delay parameter, the observation and augmented data are reconstructed. By using the filter operator and some auxiliary vectors, the parameter identification error vector is derived. Based on the parameter identification error term and initial estimation error term, a novel criterion function is invented. In comparison to the common criterion function, a classy estimation property is provided based on the criterion function in that paper because the identification error term can lift estimation accuracy, and the initial estimation error term speeds up the convergence. Under the persistent excitation condition, convergence of the developed estimator is analyzed. The availability and superiority of proposed identification scheme are verified by both numerical simulation and a turntable servo system.