scholarly journals Adaptive Fractional-Order Nonsingular Fast Terminal Sliding Mode Control for Manipulators

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xin Zhang ◽  
Ran Shi
Keyword(s):  
Control System ◽  
Fractional Order ◽  
Sliding Mode ◽  
External Disturbance ◽  
Convergence Speed ◽  
System State ◽  
Terminal Sliding Mode ◽  
Reaching Law ◽  
Fast Terminal Sliding Mode ◽  
Manipulator Control

When the manipulator system is subject to unknown disturbance, in order to improve the tracking accuracy of the manipulator, this paper designs a fractional-order nonsingular fast terminal sliding mode (FONFTSM) controller. The controller is divided into three parts. First of all, in order to improve the performance of the sliding stage, this paper designs a FONFTSM surface. By introducing a fractional-order operator, the convergence speed and accuracy of the system state are effectively improved. Secondly, in view of the problems of large chattering and slow convergence speed in the reaching stage, this paper designs a variable exponential power-reaching law (VEPRL), which has the ability to change the exponential coefficients according to the system state adaptively. At the same time, an adaptive law is designed to adjust the coefficients of the reaching law adaptively, which enhances the robustness of the control system. Finally, a disturbance observer is used to estimate the unknown external disturbance in real time so as to perform feedforward compensation for the control system, which effectively improves the accuracy of the manipulator control system. The stability of the manipulator control system is proved by the Lyapunov function. Simultaneously, the controller designed in this paper is compared with different controllers, which proves that the controller designed in this paper has strong robustness, high control accuracy, and fast convergence speed.

Research on adaptive non-singular fast terminal sliding mode control based on variable exponential power reaching law in manipulators

2021 ◽  
pp. 095965182110402
Author(s):  
Xin Zhang ◽  
Ran Shi
Keyword(s):  
Control System ◽  
Upper Bound ◽  
Sliding Mode ◽  
Convergence Speed ◽  
Terminal Sliding Mode Control ◽  
Terminal Sliding Mode ◽  
Slow Convergence ◽  
Reaching Law ◽  
Fast Terminal Sliding Mode ◽  
Exponential Power

Aiming at the manipulator control system is susceptible to model parameter uncertainty and external disturbance. In this article, an adaptive non-singular fast terminal sliding mode control based on variable exponential power reaching law is proposed. First, due to the slow convergence speed and large chattering of the traditional reaching law, the variable exponential power reaching law is designed in this article. It can adaptively change the reached speed according to the system state, improve the accuracy of the control system and reduce chattering. Second, compared to the slow convergence speed of traditional sliding mode surfaces, this article uses non-singular fast terminal sliding mode surfaces to speed up the system error convergence speed. At the same time, in view of the problem that the disturbance has an uncertain upper bound in the actual problem, the adaptive law is used to estimate the uncertain upper bound of the system disturbance. And by introducing a time-varying boundary layer to improve the symbolic function in the control law. Finally, the Lyapunov function is used to prove the stability of the control system. The simulation results show that the controller designed in this article has good position tracking performance and strong anti-disturbance ability.

scholarly journals Nonsingular Fast Terminal Sliding Mode Observer and Fractional-Order Software Phase-Locked Loop for Speed-Sensorless Control of Interior Permanent Magnet Synchronous Motor

2021 ◽  
Vol 25 (1) ◽  
pp. 83-89
Author(s):  
Kaihui Zhao ◽  
Ruirui Zhou ◽  
Jinhua She ◽  
Aojie Leng ◽  
Wangke Dai ◽  
...  
Keyword(s):  
Permanent Magnet ◽  
Fractional Order ◽  
Sliding Mode ◽  
Permanent Magnet Synchronous Motor ◽  
Phase Locked Loop ◽  
Synchronous Motor ◽  
Sliding Mode Observer ◽  
Terminal Sliding Mode ◽  
Fast Terminal Sliding Mode ◽  
Interior Permanent Magnet

In this paper, a novel method is presented to improve the speed-sensorless control performance of an interior permanent magnet synchronous motor using a nonsingular fast terminal sliding-mode observer and fractional-order software phase-locked loop. The interior permanent magnet synchronous motor system is first described. Next, a nonsingular fast terminal sliding mode observer is constructed to estimate the d-q-axis back electromotive force. The speed and position of the rotor are then accurately tracked using a fractional-order software phase-locked loop. The effectiveness and feasibility are verified through a simulation in MATLAB/Simulink. The results show an excellent performance despite a fluctuation in speed and torque ripple.

Fractional-order adaptive controller for chaotic synchronization and application to a dual-channel secure communication system

2019 ◽  
Vol 33 (24) ◽  
pp. 1950290 ◽  
Author(s):  
Ye Li ◽  
Haoping Wang ◽  
Yang Tian
Keyword(s):  
Fractional Order ◽  
Communication System ◽  
Secure Communication ◽  
Sliding Mode ◽  
External Disturbance ◽  
Lyapunov Stability Theory ◽  
Adaptive Controller ◽  
Sliding Mode Controller ◽  
Terminal Sliding Mode ◽  
Dual Channel

A novel fractional-order adaptive non-singular terminal sliding mode control (FONTSMC) method is investigated for the synchronization of two nonlinear fractional-order chaotic systems in the presence of external disturbance. The proposed controller consists of a fractional-order non-singular terminal sliding mode surface and an adaptive gain adjusted with sliding surface. Based on Lyapunov stability theory and stability theorem for fractional-order dynamic systems, the controlled system’s stable synchronization is guaranteed. A dual-channel secure communication system is presented to transmit useful signals based on the proposed synchronization controller. Finally, numerical simulations and comparison with fractional-order PID controller, fractional-order PD sliding mode controller and adaptive terminal sliding mode controller are given to demonstrate the effectiveness and the robustness of the proposed FONTSMC control. The application of the proposed synchronization method is studied in the dual-channel secure communication.

Model-free control using time delay estimation and fractional-order nonsingular fast terminal sliding mode for uncertain lower-limb exoskeleton

2018 ◽  
Vol 24 (22) ◽  
pp. 5273-5290 ◽  
Author(s):  
Saim Ahmed ◽  
Haoping Wang ◽  
Yang Tian
Keyword(s):  
Fractional Order ◽  
Lower Limb ◽  
Sliding Mode ◽  
Time Delay Estimation ◽  
Delay Estimation ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Robotic Exoskeleton ◽  
Model Free ◽  
Fast Terminal Sliding Mode

A robotic exoskeleton is a nonlinear system, which is subjected to parametric uncertainties and external disturbances. Due to this reason, it is difficult to obtain the exact model of the system, and without knowledge of the system, it cannot be compensated accurately. In this study, time delay estimation (TDE)-based model-free fractional-order nonsingular fast terminal sliding mode control (MFF-TSM) is proposed for the lower-limb robotic exoskeleton in the existence of uncertainties and external disturbance. The main characteristic of the proposed scheme is that it controls the system without relying on the knowledge of exoskeleton dynamics. At first, the fractional-order (FO) with nonsingular fast terminal sliding mode control (NFTSM) is adopted to provide a precise trajectory tracking performance, fast finite-time speed of convergence, singularity-free and chatter-free control inputs. And then, the proposed controller employs TDE, to make the controller model independent, which directly estimates the uncertain exoskeleton dynamics with external disturbances. Later, asymptotical stability analysis of the overall system and finite-time convergence are investigated and ensured using Lyapunov theorem. Finally, the simulation results are conducted to validate the efficacy of the proposed control method.

scholarly journals Fractional-Order Fast Terminal Sliding Mode Control for a Class of Dynamical Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Guoliang Zhao
Keyword(s):  
Dynamical Systems ◽  
Sliding Mode Control ◽  
Fractional Order ◽  
Sliding Mode ◽  
Lyapunov Stability Theory ◽  
Terminal Sliding Mode Control ◽  
Terminal Sliding Mode ◽  
Finite Time Stability ◽  
Mode Control ◽  
Fast Terminal Sliding Mode

This paper introduces a novel fractional fast terminal sliding mode control strategy for a class of dynamical systems with uncertainty. In this strategy, a fractional-order sliding surface is proposed, the corresponding control law is derived based on Lyapunov stability theory to guarantee the sliding condition, and the finite time stability of the closeloop system is also ensured. Further, to achieve the equivalence between convergence rate and singularity avoidance, a fractional-order nonsingular fast terminal sliding mode controller is studied and the stability is presented. Finally, numerical simulation results are presented to illustrate the effectiveness of the proposed method.

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