Nonsingular terminal sliding mode control of underwater remotely operated vehicles

Intl J Robust & Nonlinear

Yan

Zhu

et al. 2019

Self Cite

In this paper, a new practical robust control scheme is proposed and investigated for the cable-driven manipulators under lumped uncertainties. There are three parts in the proposed method, ie, a time-delay estimation (TDE) part, a modified super-twisting algorithm (STA) part, and a fractional-order nonsingular terminal sliding mode (FONTSM) error dynamics part. The TDE uses intentionally time-delayed system signals to estimate the lumped dynamics of the system and ensures an attractive model-free control structure. The STA is applied to guarantee high performance and chattering suppression simultaneously in the reaching phase. The FONTSM error dynamics is utilized to obtain fast convergence and strong robustness in the sliding mode phase. Thanks to the above three parts, the proposed control scheme is model free and can ensure high control performance under lumped uncertainties. The stability considering the FONTSM error dynamics and modified STA scheme is analyzed. Comparative simulation and experiments were conducted to demonstrate the effectiveness and superiorities of the newly proposed control scheme. Corresponding experimental results show that our newly proposed control scheme can provide more than 20% improvement of the steady control accuracy under three different reference trajectories. KEYWORDS cable-driven manipulators, fractional order, model free, nonsingular terminal sliding mode, super-twisting algorithm (STA), time-delay estimation (TDE) INTRODUCTIONRobot manipulators have been widely utilized in many practical fields benefitting from their excellent capability to execute automatic tasks. 1-4 Usually, the drive motors are directly installed in the joints to simplify the system structure and obtain good control accuracy, which in turn will bring in high stiffness and big moving inertia. This design performs well for the industrial applications, but it will not be safe for the physical interactions with human due to the high stiffness and large moving mass. Therefore, the cable-driven manipulators were proposed and utilized to efficiently settle the above issue. 5 Compared with the widely used classical robot manipulators, the cable-driven ones have much lower stiffness and smaller moving mass, which can effectively guarantee the safety for physical interactions with human. Due to above obvious advantages, cable-driven manipulators have been widely used in medical care, flexible manufacturing, and academic studies. [6][7][8][9][10][11][12] Int J Robust Nonlinear Control. 2019;29:3405-3425.wileyonlinelibrary.com/journal/rnc

Section: Introductionmentioning

confidence: 99%

A new practical robust control of cable‐driven manipulators using time‐delay estimation

Intl J Robust & Nonlinear

Yan

Zhu

et al. 2019

Self Cite

“…Then, the following nonsingular fast terminal sliding mode (NFTSM) surface and fast-TSMtype reaching law are designed as 19,20 s = e + k 1 sig e ð Þ a + k 2 sig _ e ð Þ b ð9Þ…”

Section: Tde-based Cnftsm Controller Designmentioning

confidence: 99%

“…Define the tracking errors as e = ζ d − ζ , e · = ζ · d − ζ · and e ·· = ζ ·· d − ζ ·· . Then, the following nonsingular fast terminal sliding mode (NFTSM) surface and fast-TSM-type reaching law are designed as 19,20…”

Section: Tde-based Cnftsm Controller Designmentioning

confidence: 99%

Joint space tracking control of underwater vehicle-manipulator systems using continuous nonsingular fast terminal sliding mode

Proceedings of the Institution of Mechanical Engineers, Part M:

Chen

2017

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To ensure satisfactory control performance for the underwater vehicle-manipulator systems, a novel continuous nonsingular fast terminal sliding mode controller is proposed and investigated using time delay estimation in this article. Complex lumped unknown dynamics including the strong nonlinear couplings and external disturbance are properly compensated with time delay estimation, which are mainly based on the time-delayed signals of underwater vehiclemanipulator systems and can provide with a fascinating model-free feature. Afterwards, the satisfactory tracking control performance and good robustness under heavy lumped uncertainties are ensured using the continuous nonsingular fast terminal sliding mode term with a fast terminal sliding mode-type reaching law. Therefore, the proposed controller is easy to use thanks to time delay estimation, and can ensure good control performance owing to continuous nonsingular fast terminal sliding mode. Stability of the closed-loop control system is analyzed using Lyapunov stability theory, and theoretical tracking errors are calculated and presented. Finally, the effectiveness and advantages of the proposed controller are demonstrated through comparative 7-degree-of-freedom pool experiments.

“…The proposed method utilizes TDE to obtain the system dynamics and applied TSM error dynamics to guarantee high control accuracy. Thanks to the attractive finite time convergence nature and high performance near the equilibrium point, TSM control has been widely used in many systems [31][32][33][34][35][36][37][38][39][40][41]. Recently, a novel continuous NTSM (CNTSM) scheme has been proposed and investigated for the control purpose of robot manipulators [42,43].…”

Section: Introductionmentioning

confidence: 99%

A New Model-Free Trajectory Tracking Control for Robot Manipulators

Mathematical Problems in Engineering

Zhu

Chen

et al. 2018

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In this paper, we propose a novel model-free trajectory tracking control for robot manipulators under complex disturbances. The proposed method utilizes time delay control (TDC) as its control framework to ensure a model-free scheme and uses adaptive nonsingular terminal sliding mode (ANTSM) to obtain high control accuracy and fast dynamic response under lumped disturbance. Thanks to the application of adaptive law, the proposed method can ensure high tracking accuracy and effective suppression of noise effect simultaneously. Stability of the closed-loop control system is proved using Lyapunov method. Finally, the effectiveness and advantages of the newly proposed TDC scheme with ANTSM dynamics are verified through several comparative simulations.