Model-free super-twisting terminal sliding mode controller using sliding mode disturbance observer for n-DOF upper-limb rehabilitation exoskeleton with backlash hysteresis

He, Dingxin; Wang, Haoping; Tian, Yang

doi:10.1080/00207179.2023.2173994

Cited by 2 publications

(1 citation statement)

References 74 publications

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“…Due to the above advantages, the ULM‐based MFC has been successfully applied to systems such as manipulators, 24 exoskeletons, 25 and automotive suspensions 22 . Although the proposed model‐free control has been combined with methods such as observers, 26 sliding mode control, 27 and fractional order control, 28 the convergence proof of the above methods can only satisfy the finite time convergence, which means that the initial value will affect the convergence time of the controllers.…”

Section: Introductionmentioning

confidence: 99%

Fixed‐time asymmetric barrier Lyapunov function‐based model‐free hybrid position/force control for 3‐DOF SEA‐based manipulator with output constraints

Wei,

Wang,

Tian

2023

Intl J Robust & Nonlinear

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In this work, a fixed‐time asymmetric barrier Lyapunov function (BLF)‐based model‐free hybrid position/force controller (FBMHC) is proposed for 3‐DOF SEA‐based manipulator for large surface machining with asymmetric time‐varying output constraints. The proposed FBMHC has a dual‐loop structure, which consists of a force sub‐control loop and a position sub‐control loop. The force sub‐control loop converts the control of the interaction force into position control through the idea of impedance control. The position sub‐control loop is designed under the model‐free control framework, which includes asymmetric time‐varying BLF, time‐delay estimator (TDE), and adaptive compensation term, so as to reduce the complexity of controller design and keep the joint angles within the asymmetric time‐varying output constraints. Strict mathematical derivation proves that the proposed method can achieve fixed‐time convergence, so the influence of the initial value on the control effect is reduced. Finally, the effectiveness of FBMHC is verified by comparison simulation with TDE‐intelligent PD and finite time BLF‐based model‐free control.

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Section: Introductionmentioning

confidence: 99%

Fixed‐time asymmetric barrier Lyapunov function‐based model‐free hybrid position/force control for 3‐DOF SEA‐based manipulator with output constraints

Wei,

Wang,

Tian

2023

Intl J Robust & Nonlinear

Self Cite

View full text Add to dashboard Cite

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A novel hybrid observer‐based model‐free adaptive high‐order terminal sliding mode control for robot manipulators with prescribed performance

Zha,

Wang,

Tian

et al. 2024

Intl J Robust & Nonlinear

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Although widely used in industrial applications, strong nonlinearity and coupling, high computational complexity prevent high precision tracking control of manipulator. In this paper, to overcome the rely on system model and achieve prescribed convergence, a novel hybrid observer‐based model‐free adaptive high‐order fast terminal sliding model control scheme (HO‐MHTSMC) with prescribed performance is proposed for trajectory tracking control of robot manipulators in the existence of friction and external disturbance. The ultra‐local model is used to approximate the original complex system in a model free form in a short sliding time window, which avoid the accurate modeling of the manipulator system. To compensate for the lumped uncertainties, a hybrid observer based on adaptive time‐delay estimation and adaptive second order sliding mode observer (SOSM) is proposed to achieve finite‐time observation and zero estimation error. Besides, a transformation using prescribed performance function is applied to the system to ensure the transient and steady‐state performance of the trajectory tracking in joint space. Furthermore, a high‐order fast terminal sliding mode control algorithm with backstepping control strategy is used to stabilize the whole system and reduce the chattering problem in conventional sliding mode control. The stability analysis of the system is provided by Lyapunov theorem. Finally, numerical study and co‐simulations show that the proposed control scheme has better performance in tracking accuracy and robustness compared with conventional control schemes.

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Model-free super-twisting terminal sliding mode controller using sliding mode disturbance observer for n-DOF upper-limb rehabilitation exoskeleton with backlash hysteresis

Cited by 2 publications

References 74 publications

Fixed‐time asymmetric barrier Lyapunov function‐based model‐free hybrid position/force control for 3‐DOF SEA‐based manipulator with output constraints

Fixed‐time asymmetric barrier Lyapunov function‐based model‐free hybrid position/force control for 3‐DOF SEA‐based manipulator with output constraints

A novel hybrid observer‐based model‐free adaptive high‐order terminal sliding mode control for robot manipulators with prescribed performance

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