scholarly journals Robust Sliding Mode Control Based on GA Optimization and CMAC Compensation for Lower Limb Exoskeleton

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Yi Long ◽  
Zhi-jiang Du ◽  
Wei-dong Wang ◽  
Wei Dong
Keyword(s):  
Sliding Mode Control ◽  
Control Strategy ◽  
Lower Limb ◽  
Position Control ◽  
Sliding Mode ◽  
Angular Position ◽  
Human Motion ◽  
Cerebellar Model Articulation Controller ◽  
Mode Control ◽  
First Case

A lower limb assistive exoskeleton is designed to help operators walk or carry payloads. The exoskeleton is required to shadow human motion intent accurately and compliantly to prevent incoordination. If the user’s intention is estimated accurately, a precise position control strategy will improve collaboration between the user and the exoskeleton. In this paper, a hybrid position control scheme, combining sliding mode control (SMC) with a cerebellar model articulation controller (CMAC) neural network, is proposed to control the exoskeleton to react appropriately to human motion intent. A genetic algorithm (GA) is utilized to determine the optimal sliding surface and the sliding control law to improve performance of SMC. The proposed control strategy (SMC_GA_CMAC) is compared with three other types of approaches, that is, conventional SMC without optimization, optimal SMC with GA (SMC_GA), and SMC with CMAC compensation (SMC_CMAC), all of which are employed to track the desired joint angular position which is deduced from Clinical Gait Analysis (CGA) data. Position tracking performance is investigated with cosimulation using ADAMS and MATLAB/SIMULINK in two cases, of which the first case is without disturbances while the second case is with a bounded disturbance. The cosimulation results show the effectiveness of the proposed control strategy which can be employed in similar exoskeleton systems.

Electro-Hydraulic Servo System Controlled by Index Reaching Law Sliding Mode

2011 ◽  
Vol 317-319 ◽  
pp. 1490-1494 ◽  
Author(s):  
Bao Quan Jin ◽  
Yan Kun Wang ◽  
Ya Li Ma
Keyword(s):  
Sliding Mode Control ◽  
Control Strategy ◽  
Position Control ◽  
Sliding Mode ◽  
External Disturbance ◽  
Servo System ◽  
Response Speed ◽  
Reaching Law ◽  
Mode Control ◽  
Hydraulic Servo

The parameters uncertainty and external disturbance play a negative role to improve electro-hydraulic position servo system performance. The valve controlled cylinder system model is established, using the traditional PID control strategy and reaching law control strategy for simulating the system, respectively, the two methods have similar control effects in the ideal model, but considering the external disturbances, the index approaches sliding mode control law has better response speed and stability. Research shown that sliding mode control algorithm has an important role for improving the performance of hydraulic servo position control system.

Adaptive-gain fast nonsingular terminal sliding mode for position control of a piezo positioning stage

2018 ◽  
Vol 232 (8) ◽  
pp. 994-1014 ◽  
Author(s):  
To Xuan Dinh ◽  
Kyoung Kwan Ahn
Keyword(s):  
Sliding Mode Control ◽  
Position Control ◽  
Sliding Mode ◽  
Terminal Sliding Mode Control ◽  
Cerebellar Model Articulation Controller ◽  
Terminal Sliding Mode ◽  
Control Approach ◽  
Mode Control ◽  
Uncertainty Model ◽  
Positioning Stage

This article proposed a variable gain fast terminal sliding mode controller with an estimator of the uncertainty model for a piezo positioning stage system. The designed terminal sliding mode control has some advantages over the linear sliding mode control such as fast convergence and chattering reduction while maintains its robustness to the uncertainties. Next, an indirect technique is developed to enable the elimination of the singularity problem corresponding to initial terminal sliding mode control. In addition, a cerebellar model articulation controller is carried out to estimate the nonlinear dynamics of the piezo positioning stage. To deal with unknown bounds of uncertainties and disturbances, the proposed scheme consists of using online tuning control gains that ensure the establishment of a real terminal sliding mode in a finite time. Moreover, a fuzzy logic scheme is presented to smooth out the discontinuity part of the control signal, hence improve the control performance. Stability analysis of closed loop system is provided using the Lyapunov function method. Experiment results are presented to evaluate the effectiveness of the designed control approach.

Sliding Mode Control of an Actuated Knee Joint Orthosis

2021 ◽  
Vol 15 ◽  
Author(s):  
Imen Saidi ◽  
Asma Hammami
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Sliding Mode ◽  
Position Tracking ◽  
Sliding Mode Controller ◽  
Mechanical Device ◽  
Tracking Errors ◽  
Mode Control ◽  
Speed Tracking ◽  
Human Morphology

Introduction: In this paper, a robust sliding mode controller is developed to control an orthosis used for rehabilitation of lower limb. Materials and Methods: The orthosis is defined as a mechanical device intended to physically assist a human subject for the realization of his movements. It should be adapted to the human morphology, interacting in harmony with its movements, and providing the necessary efforts along the limbs to which it is attached. Results: The application of the sliding mode control to the Shank-orthosis system shows satisfactory dynamic response and tracking performances. Conclusion: In fact, position tracking and speed tracking errors are very small. The sliding mode controller effectively absorbs disturbance and parametric variations, hence the efficiency and robustness of our applied control.

scholarly journals Backstepping Sliding-Mode Control of Piezoelectric Single-Piston Pump-Controlled Actuator

Actuators ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 154
Author(s):  
Bin Wang ◽  
Pengda Ren ◽  
Xinhao Huang
Keyword(s):  
Sliding Mode Control ◽  
Position Control ◽  
Control Method ◽  
Sliding Mode ◽  
Piezoelectric Pump ◽  
Mode Control ◽  
Control Precision ◽  
Backstepping Sliding Mode Control ◽  
Actuator System ◽  
The Mathematical Model

A piston piezoelectric (PZT) pump has many advantages for the use of light actuators. How to deal with the contradiction between the intermittent oil supplying and position control precision is essential when designing the controller. In order to accurately control the output of the actuator, a backstepping sliding-mode control method based on the Lyapunov function is introduced, and the controller is designed on the basis of establishing the mathematical model of the system. The simulation results show that, compared with fuzzy PID and ordinary sliding-mode control, backstepping sliding-mode control has a stronger anti-jamming ability and tracking performance, and improves the control accuracy and stability of the piezoelectric pump-controlled actuator system.

Design of M-G modal space sliding mode control for lower limb exoskeleton robot driven by electrical actuators

Mechatronics ◽  
2021 ◽  
Vol 78 ◽  
pp. 102610
Author(s):  
Jinsong Zhao ◽  
Tao Yang ◽  
Zhilei Ma ◽  
Chifu Yang ◽  
Zhipeng Wang ◽  
...  
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Sliding Mode ◽  
Lower Limb Exoskeleton ◽  
Mode Control ◽  
Exoskeleton Robot ◽  
Modal Space

Conditional integrator sliding mode control of an unmanned quadrotor helicopter

2021 ◽  
pp. 095965182110498
Author(s):  
Yohan Díaz-Méndez ◽  
Leandro Diniz de Jesus ◽  
Marcelo Santiago de Sousa ◽  
Sebastião Simões Cunha ◽  
Alexandre Brandão Ramos
Keyword(s):  
Sliding Mode Control ◽  
Transient Response ◽  
Tracking Control ◽  
Position Control ◽  
Sliding Mode ◽  
Control Technique ◽  
Control Law ◽  
Control Problems ◽  
Control Activity ◽  
Mode Control

Sliding mode control (SMC) is a widely used control law for quadrotor regulation and tracking control problems. The purpose of this article is to solve the tracking problem of quadrotors using a relatively novel nonlinear control law based on SMC that makes use of a conditional integrator. It is demonstrated by a motivation example that the proposed control law can improve the transient response and chattering shortcomings of the previous approaches of similar SMC based controllers. The adopted Newton–Euler model of quadrotor dynamics and controller design is treated separately in two subsystems: attitude and position control loops. The stability of the control technique is demonstrated by Lyapunov’s analysis and the effectiveness and performance of the proposed method are compared with a similar integral law, also based on SMC, and validated by tracking control problems using numerical simulations. Simulations were developed in the presence of external disturbances in order to evaluate the controller robustness. The effectiveness of the proposed controller was verified by performance indexes, demonstrating less accumulated tracking errors and control activity and improvement in the transient response and disturbance rejection when compared to a conventional integrator sliding mode controller.

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