An Improved Nonlinear Tracking Differentiator and its Application

An improved nonlinear tracking differentiator(INTD) with limited control variable is proposed in this paper. Compared with the existing high speed nonlinear tracking differentiators(HSTD), INTD preserves the stability of HSTDs at the target state and their rapidity. In particular, the HSTD's problem of poor anti-interference ability and narrow application range is solved by INTD. This paper analyzes the tracking performance of INTD with different threshold coefficient of control variable and processing different step signals under the same threshold coefficient. It is verified that HSTD needs a proper limit for control variable. INTD is applied to process the magnetic phase signal of maglev train position and speed detection system, the result shows that this improved nonlinear tracking differentiator can well track and filtering phase angle signal.