Research Of Parameter Adaptive Sliding Mode Differentiator

Deriving the derivative of the signal by filtering out noise in the input signal has long been regarded as an important topic in control systems.In the early days,the differential method was used to obtain the derivative of the input signal.Although the differential method is convenient and easy to implement,it will amplify the noise in the input signal during differential estimation,and the smaller the period is,the more significant the noise amplification effect is.The system will undoubtedly reduce the control accuracy of the system.With the deepening of research,it is generally considered a practical method to use filters to deal with noise signals.Linear filters are often used as the first choice for processing noisy signals because of their simple structure and low computational cost.However,the linear filter has certain defects: First,in the case of strong noise reduction,the phase lag of the output signal is large.Second,noise is proportionally introduced into the output signal.On the other hand,although the median filter,adaptive window filter,and Kalman filter can reduce the phase lag when filtering noise,there are still problems such as the estimation accuracy being affected by the window size and depending on the system model.In recent years,the sliding mode tracking differentiator(SMTD),which does not depend on the system model and has the characteristics of strong robustness and filtering,has gradually become a popular research direction in the field of control theory.In this paper,the research on the improvement of the response speed and filtering performance of the sliding mode tracking differentiator is carried out.On the basis of analyzing the existing problems of the robust sliding mode tracking differentiator(SMTD-E)proposed by Efimov et al.,the structure is improved,and a new parameter adaptive sliding mode tracking differentiator(SMTD-N)is proposed.The main research contents are as follows:Aiming at the contradiction between balancing response speed and filtering performance of SMTD-E,a novel parameter adaptive sliding mode tracking differentiator(SMTD-N)is proposed.By adding nonlinear functions and adaptive functions,the filtering performance can be effectively improved without affecting the state convergence speed of the SMTD-N system.To achieve the purpose of taking into account both fast response and good filtering performance.In addition,through numerical simulation,the influence of its parameters on the system performance is analyzed,which provides a reference for parameter selection.Finally,the performance of SMTD-N is verified by time-domain output and quantitative evaluation with step signal and dynamic signal as the input signal.The results show that SMTD-N can simultaneously improve the response speed and filtering performance.