scholarly journals A Self-Adaptive-Coefficient-Double-Power Sliding Mode Control Method for Lower Limb Rehabilitation Exoskeleton Robot

2021 ◽  
Vol 11 (21) ◽  
pp. 10329
Author(s):  
Yuepeng Zhang ◽  
Guangzhong Cao ◽  
Wenzhou Li ◽  
Jiangcheng Chen ◽  
Linglong Li ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Sliding Mode Control ◽  
Lower Limb ◽  
Control Method ◽  
Sliding Mode ◽  
Control Law ◽  
Mode Control ◽  
Limb Rehabilitation ◽  
Lower Limb Rehabilitation ◽  
Self Adaptive

Lower limb rehabilitation exoskeleton robots have the characteristics of nonlinearity and strong coupling, and they are easily disturbed during operation by environmental factors. Thus, an accurate dynamic model of the robot is difficult to obtain, and achieving trajectory tracking control of the robot is also difficult. In this article, a self-adaptive-coefficient double-power sliding mode control method is proposed to overcome the difficulty of tracking the robot trajectory. The method combines an estimated dynamic model with sliding mode control. A nonlinear control law was designed based on the robot dynamics model and computational torque method, and a compensation term of control law based on double-power reaching law was introduced to reduce the disturbance from model error and environmental factors. The self-adaptive coefficient of the compensation term of the control law was designed to adaptively adjust the compensation term to improve the anti-interference ability of the robot. The simulation and experiment results show that the proposed method effectively improves the trajectory tracking accuracy and anti-interference ability of the robot. Compared with the traditional computed torque method, the proposed method decreases the tracking error by more than 71.77%. The maximum absolute error of the hip joint and knee joint remained below 0.55° and 1.65°, respectively, in the wearable experiment of the robot.

Impedance Control Based Sliding Mode for Lower Limb Rehabilitation Robot

2014 ◽  
Vol 672-674 ◽  
pp. 1770-1773 ◽  
Author(s):  
Fu Cheng Cao ◽  
Li Min Du
Keyword(s):  
Dynamic Response ◽  
Sliding Mode Control ◽  
Lower Limb ◽  
Control Method ◽  
Sliding Mode ◽  
Impedance Control ◽  
Rehabilitation Robot ◽  
Active Rehabilitation ◽  
Limb Rehabilitation ◽  
Lower Limb Rehabilitation

Aimed at improving the dynamic response of the lower limb for patients, an impedance control method based on sliding mode was presented to implement an active rehabilitation. Impedance control can achieve a target-reaching training without the help of a therapist and sliding mode control has a robustness to system uncertainty and vary limb strength. Simulations demonstrate the efficacy of the proposed method for lower limb rehabilitation.

scholarly journals Vibration Reduction of the Nonlinearly Tufted Carpet Yarn by a Modified Sliding Mode Control Method

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Shuang Huang ◽  
Xin Wu ◽  
Peixing Li
Keyword(s):  
Sliding Mode Control ◽  
High Frequency ◽  
Control Algorithm ◽  
Control Method ◽  
Sliding Mode ◽  
Control Law ◽  
Control Force ◽  
Fuzzy Sliding Mode Control ◽  
Mode Control ◽  
Fuzzy Sliding Mode

The yarn vibration causes the yarn tension value to fluctuate, causing a change in the amount of yarn feed, thus causing a deviation of the carpet pile height from the predetermined value. To solve this problem, the sliding mode control algorithm is used to design the sliding mode function and the sliding mode control law. And four variables in the yarn vibration system are controlled by the MATLAB software. For solving the chattering problem of the control law, the sliding mode control law is improved. The fuzzy sliding mode control algorithm based on the quasisliding mode is adopted. The results show that the sliding mode control algorithm is effective, but the sliding mode control force needs to be switched at high frequency and there is severe chattering. The fuzzy sliding mode control algorithm based on quasisliding mode is adopted to achieve better control effect with a smaller force. In addition, the control force does not have high-frequency switching, and the change is relatively stable, which reduces the chattering phenomenon of sliding mode control.

scholarly journals Control of Chaos in Rate-Dependent Friction-Induced Vibration Using Adaptive Sliding Mode Control and Impulse Damper

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Ehsan Maani Miandoab ◽  
Aghil Yousefi-Koma ◽  
Saeed Hashemnia
Keyword(s):  
Sliding Mode Control ◽  
Control Method ◽  
Sliding Mode ◽  
Control Technique ◽  
Adaptive Sliding Mode Control ◽  
Control Law ◽  
Adaptive Sliding Mode ◽  
Chaotic Vibration ◽  
Mode Control ◽  
Rate Dependent

Two different control methods, namely, adaptive sliding mode control and impulse damper, are used to control the chaotic vibration of a block on a belt system due to the rate-dependent friction. In the first method, using the sliding mode control technique and based on the Lyapunov stability theory, a sliding surface is determined, and an adaptive control law is established which stabilizes the chaotic response of the system. In the second control method, the vibration of this system is controlled by an impulse damper. In this method, an impulsive force is applied to the system by expanding and contracting the PZT stack according to efficient control law. Numerical simulations demonstrate the effectiveness of both methods in controlling the chaotic vibration of the system. It is shown that the settling time of the controlled system using impulse damper is less than that one controlled by adaptive sliding mode control; however, it needs more control effort.

Adaptive smooth second-order sliding mode control method with application to missile guidance

2015 ◽  
Vol 39 (6) ◽  
pp. 848-860 ◽  
Author(s):  
Zheng Wang
Keyword(s):  
Sliding Mode Control ◽  
Finite Time ◽  
Control Method ◽  
Sliding Mode ◽  
Second Order ◽  
Control Law ◽  
Smooth Control ◽  
Mode Control ◽  
Control Command ◽  
Second Order Sliding Mode

This paper proposes an adaptive smooth second-order sliding mode control law for a class of uncertain non-linear systems. The key point of this control law is ensuring a smooth control signal considering parametric uncertainty and disturbances with unknown bounds. The proposed control method is obtained by introducing a continuous function under the integral and using adaptive gains. The switching function and its derivative are forced to zero in finite time. This is achieved using a smooth control command and without the prior knowledge of upper bound parameters of uncertainties. The finite-time stability is proved based on a quadratic Lyapunov approach and the reaching time is estimated. This structure is used to create a homing guidance law and the efficiency is evaluated via simulations.

Force Control Based on Model Predictive for Lower Limb Rehabilitation Training

2015 ◽  
Vol 738-739 ◽  
pp. 991-994
Author(s):  
Fu Cheng Cao ◽  
Hong Wu Qin
Keyword(s):  
Force Control ◽  
Lower Limb ◽  
Control Method ◽  
Control Strategies ◽  
Industrial Robot ◽  
Control Law ◽  
Rehabilitation Robot ◽  
Patient Centered ◽  
Limb Rehabilitation ◽  
Lower Limb Rehabilitation

Human as a varying dynamic system, the control strategies of human-robot interacts differ significantly from that of conventional industrial robot. Considered the patient-centered exercise regimens, a force control method based predict is presented to control a lower limb rehabilitation robot. The control law is introduced that optimises the the maintained force level and limits excessive forceto injury the subject's lower extremity joints. Simulation results show that the robot could guide thelower limb of subjects to move under predefined model of the external force.

Sliding Mode Control of Magnetic Bearing System Based on Variable Rate Reaching Law

2011 ◽  
Vol 460-461 ◽  
pp. 827-830 ◽  
Author(s):  
Jing Feng Mao ◽  
Ai Hua Wu ◽  
Guo Qing Wu ◽  
Xu Dong Zhang
Keyword(s):  
Sliding Mode Control ◽  
Control Method ◽  
Sliding Mode ◽  
Magnetic Bearing ◽  
System Stability ◽  
Control Law ◽  
Variable Rate ◽  
Reaching Law ◽  
Mode Control ◽  
Bearing System

In order to eliminate the chattering phenomena caused by conventional sliding mode control (SMC) method in magnetic bearing system control, this paper proposes a variable rate reaching law approach based sliding mode controller to achieve higher system stability and robustness. In this control law, system states’ normal numbers are brought in to automatic adjust the gain of the switching control part of SMC. The controller output amplitude of chattering can be progressively damped, and the system will converge to zero asymptotically. The system stability is proved by Laypunov theory, and the prerequisite of control law parameters design is deduced out. Simulation results show that the proposed SMC control method has effectiveness in dynamic suspension position tracking performance and obtaining system robustness.

Observer based direct adaptive fuzzy second-order-like sliding mode control for unknown nonlinear systems

2020 ◽  
pp. 095440892095259
Author(s):  
Hongzhuang Wu ◽  
Songyong Liu ◽  
Cheng Cheng ◽  
Changlong Du
Keyword(s):  
Sliding Mode Control ◽  
Control Method ◽  
Nonlinear Dynamical Systems ◽  
Sliding Mode ◽  
Tracking Error ◽  
Second Order ◽  
Control Law ◽  
Adaptive Fuzzy ◽  
Mode Control ◽  
The Stability

This work proposes a novel observer based direct adaptive fuzzy second-order-like sliding mode control (SMC) method for a certain class of high order unknown nonlinear dynamical systems with unmeasurable states. An observer is firstly developed to estimate the tracking error vector directly, and the stability of the observer is analyzed based on Meyer-Kalman-Yakubovich (MKY) lemma. Based on the observer, the equivalent control law is approximated by a double-input single-output fuzzy logic system (FLS), in which the observation of the sliding surface and its derivative are applied as the inputs. In addition, an adaptive switching control law is added to mitigate the system chattering and improve the stability of the system. The free parameters of the controller are adjusted online by the adaptive laws that are derived from the Lyapunov stability analysis. Finally, the convergence of the overall closed-loop system is demonstrated, and the simulation examples illustrate the efficacy of the proposed control method.

Adaptive sliding mode formation control for multiple flight vehicles with considering autopilot dynamic

2021 ◽  
pp. 1-21
Author(s):  
W. Li ◽  
Q. Wen ◽  
H. Zhou
Keyword(s):  
Sliding Mode Control ◽  
Formation Control ◽  
Control Method ◽  
Sliding Mode ◽  
Dimensional Space ◽  
External Disturbance ◽  
Control Law ◽  
Terminal Sliding Mode ◽  
Mode Control ◽  
Flight Vehicles

ABSTRACT This paper mainly focuses on the cooperative control of formation configuration for multiple flight vehicles in the three-dimensional space. Considering the external disturbance of the system, the adaptive non-singular terminal sliding mode control law (NTSMC) is designed based on the virtual leader-follower method, which aims to ensure that each flight vehicle reaches the expected terminal position in a limited time and meet the configuration constraints. Further considering the first-order dynamic characteristic of the autopilot, a novel second-order sliding mode control (SOSMC) law is deduced with using the estimated information of sliding mode disturbance observer. The proposed control method ensures that all flight vehicles form the required space formation configuration simultaneously at a pre-designed time, and the chattering phenomenon of the sliding mode surface and acceleration response that nears the equilibrium point is effectively weaken. The stability of the proposed control law is verified by theoretical analysis and lots of mathematical simulations. The results show that the control algorithm in this paper can be used to guidance the formation controller design of multiple flight vehicles in the mid-guidance phase to some extent, and thus the cooperative flight stability of the system can be effectively improved.

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