A nonsingular fast terminal sliding mode control with an exponential reaching law for robot manipulators

2018 ◽  
Vol 233 (5) ◽  
pp. 1575-1587 ◽  
Author(s):  
Liyin Zhang ◽  
Yuxin Su ◽  
Haihong Wang
Keyword(s):  
Sliding Mode Control ◽  
Finite Time ◽  
Sliding Mode ◽  
Robot Manipulators ◽  
Terminal Sliding Mode Control ◽  
Terminal Sliding Mode ◽  
Reaching Law ◽  
Mode Control ◽  
Fast Terminal Sliding Mode ◽  
Exponential Reaching Law

This paper presents an improved robust tracking control for uncertain robot manipulators. An approximate fast terminal sliding mode control is proposed by integrating a nonsingular fast terminal sliding surface with an exponential reaching law. Lyapunov stability theory is employed to prove the global approximate finite-time stability ensuring that the tracking errors converge to an arbitrary small ball centered at zero within a finite time and thereafter arrive at zero asymptotically. The benefits of this integrated design are that it can ensure faster transient and higher steady-state tracking precision with lower chattering. Simulations and experiments are presented to demonstrate the effectiveness and improved performances of the proposed approach.

scholarly journals Novel Nonsingular Fast Terminal Sliding Mode Control for a Class of Second-Order Uncertain Nonlinear Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Huihui Pan ◽  
Guangming Zhang
Keyword(s):  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Finite Time ◽  
Sliding Mode ◽  
Second Order ◽  
Terminal Sliding Mode Control ◽  
Uncertain Nonlinear Systems ◽  
Terminal Sliding Mode ◽  
Mode Control ◽  
Fast Terminal Sliding Mode

This paper presents a novel nonsingular fast terminal sliding mode control scheme for a class of second-order uncertain nonlinear systems. First, a novel nonsingular fast terminal sliding mode manifold (NNFTSM) with adaptive coefficients is put forward, and a novel double power reaching law (NDP) with dynamic exponential power terms is presented. Afterwards, a novel nonsingular fast terminal sliding mode (NNFTSMNDP) controller is designed by employing NNFTSM and NDP, which can improve the convergence rate and the robustness of the system. Due to the existence of external disturbances and parameter uncertainties, the system states under controller NNFTSMNDP cannot converge to the equilibrium but only to the neighborhood of the equilibrium in finite time. Considering the unsatisfying performance of controller NNFTSMNDP, an adaptive disturbance observer (ADO) is employed to estimate the lumped disturbance that is compensated in the controller in real-time. A novel composite controller is presented by combining the NNFTSMNDP method with the ADO technique. The finite-time stability of the closed-loop system under the proposed control method is proven by virtue of the Lyapunov stability theory. Both simulation results and theoretical analysis illustrate that the proposed method shows excellent control performance in the existence of disturbances and uncertainties.

scholarly journals Nonsingular Terminal Sliding Mode Control of PMSM Based on Improved Exponential Reaching Law

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1776
Author(s):  
Changhong Jiang ◽  
Qiming Wang ◽  
Zonghao Li ◽  
Niaona Zhang ◽  
Haitao Ding
Keyword(s):  
Sliding Mode Control ◽  
Permanent Magnet ◽  
Sliding Mode ◽  
Permanent Magnet Synchronous Motor ◽  
Terminal Sliding Mode Control ◽  
Terminal Sliding Mode ◽  
Reaching Law ◽  
Mode Control ◽  
Nonsingular Terminal Sliding Mode ◽  
Exponential Reaching Law

When a permanent magnet synchronous motor runs at low speed, the inverter will output discontinuous current and generate torque ripple; when the motor is runs at high speed, a large amount of stator harmonic current generates, which affects its speed following ability and torque stability. To ensure the fast and smooth switching of a permanent magnet synchronous motor in the full speed domain, this paper proposes the nonsingular terminal sliding mode control of PMSM speed control based on the improved exponential reaching law. Firstly, the improved exponential reaching law is composed of the state variables and power terms of the sliding mode surface functions. The reaching law function is designed in sections to balance the fast dynamic response of the system and chattering control. Secondly, an improved exponential reaching law based on the sliding mode control strategy of the PMSM speed loop is proposed. By designing the initial value of the integral term in the nonsingular terminal sliding mode surface function, the initial state of the system is located on the sliding mode surface. The integral sliding mode surface is used to reduce the system steady-state error, while the proposed sliding mode reaching law is used to increase the arrival speed and suppress system chattering, ultimately affecting modeling error problems, complex working conditions, and uncertainty factors. This paper proposes a sliding mode observer based on an improved exponential reaching law to compensate for the disturbances. Lyapunov stability theory can prove that this system can make the speed tracking error converge to zero in finite time. Hardware-in-the-loop experiments were used to validate the effectiveness of the proposed method.

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