A new second order nonlinear tracking differentiator and application

Abstract

A Second-order nonlinear tracking differentiator ( SONTD ) constructed by a symbol function sign and a linear saturation function sat has good tracking and differential performances for smooth continuous input functions, but it isn't appropriate for step type of input functions, In order to overcome the defects of the SONTD constructed by sign and sat, a new nonlinear saturation function composed of a sine function and a sign function is introduced, and a new type of second-order nonlinear TD is constructed based on the nonlinear saturation function. The new SONTD is used in Passivity based control of voltage source PWM rectifiers to improve the transient performances of rectifiers. Simulation results show that the new type of SONTD has good tracking and differential performances for step type of input functions, but it isn't appropriate for smooth continuous input functions.

Modified Tracking Differentiator for Enhancing the Performance of Exoskeleton Knee System Based on Active Disturbance Rejection Control

“…To increase the tracking differentiator's performance, it's required to remove the tracer's complex solution, particularly the solution on the imaginary axis, and to meet the condition that the tracking differentiator converge rapidly [29], [30]. As illustrated in [31], a better tracking differentiator can be obtained in the following form:-…”

Research on Passivity-Based ADRC of Direct-Drive Wind Power System Back to Back PWM Converter

“…For the grid-side PWM inverter, the common control strategies such as feedback linearization control [7] , its stability and load disturbance-rejection ability are not ideal, therefore, we adopt passivity based control strategy [8][9], and use IDA-PBC (Interconnection and Damping Assignment Passivity Based Control) control algorithm to design passivity-based controller, which is able to make the energy function have the minimum value at the desired point and make it have greater stability and load disturbance-rejection ability. Simulation results indicate that the control strategy is feasible.…”