A Variable Gain Sliding Mode Tracking Differentiator for Derivative Estimation of Noisy Signals

Estimating reliable signal component and its derivatives from noisy feedback signal is important in control systems. Toward this problem, this article presents a new model-free variable gain sliding mode tracking differentiator for derivative estimation of noisy signals by modifying a Levant and Yu’s sliding mode tracking differentiator. Specifically, different from Levant and Yu’s TD, the new TD employs an additional variable that contributes to overshoot reduction. In addition, the new TD adaptively changes its gains for improving the tracking and filtering performances. Moreover, the new TD only uses previous output values and it does not require input signal model in advance. The advantages of the new TD over previous TDs are confirmed through numerical examples.