A Novel Exoskeleton with Fractional Sliding Mode Control for Upper Limb Rehabilitation

Robotica ◽  
2020 ◽  
Vol 38 (11) ◽  
pp. 2099-2120 ◽  
Author(s):  
Md Rasedul Islam ◽  
Mehran Rahmani ◽  
Mohammad Habibur Rahman
Keyword(s):  
Sliding Mode Control ◽  
Upper Limb ◽  
Control Algorithm ◽  
Sliding Mode ◽  
Lyapunov Theory ◽  
Upper Limb Rehabilitation ◽  
Mode Control ◽  
Wide Range ◽  
The Stability ◽  
Limb Rehabilitation

SUMMARYThe robotic intervention has great potential in the rehabilitation of post-stroke patients to regain their lost mobility. In this paper, firstly, we present a design of a novel, 7 degree-of-freedom (DOF) upper limb robotic exoskeleton (u-Rob) that features shoulder scapulohumeral rhythm with a wide range of motions (ROM) compared to other existing exoskeletons. An ergonomic shoulder mechanism with two passive DOF was included in the proposed exoskeleton to provide scapulohumeral motion with corresponding full ROM. Also, the joints of u-Rob have more range of motions compared to its existing counterparts. Secondly, we propose a fractional sliding mode control (FSMC) to control u-Rob. Applying the Lyapunov theory to the proposed control algorithm, we showed the stability of it. To control u-Rob, FSMC has shown effectiveness to handle unmodeled dynamics (e.g. friction, disturbance, etc.) in terms of better tracking and chatter compared to traditional SMC.

scholarly journals Sliding Mode Control for 2 Degrees of Freedom Upper Limb Rehabilitation Robotic System under Uncertainties

2019 ◽  
Vol 9 (2) ◽  
pp. 3268-3274
Keyword(s):  
Sliding Mode Control ◽  
Upper Limb ◽  
Degrees Of Freedom ◽  
Sliding Mode ◽  
Robotic Manipulator ◽  
Upper Limb Rehabilitation ◽  
Mode Control ◽  
Rehabilitation Robots ◽  
High Frequency Oscillations ◽  
Limb Rehabilitation

Rehabilitation of patients suffering from post-stroke injuries via robots is now adapted word widely. The aim of this therapy is to restore and improve the dysfunction and the performance of the affected limbs doing repetitive tasks with the help of rehabilitation robots, as robots are best way to perform repetitive task without any monotony failure. Control of these rehabilitation robots is an important part to consider because of nonlinearity and uncertainty of the system. This paper presents nonlinear sliding mode controller (SMC) for controlling a 2 degrees of freedom (DOF) upper limb robotic manipulator. Sliding mode control is able to handle system uncertainties and parametric changes. One drawback of using SMC is high frequency oscillations called as chattering. This chattering can be reduced by using boundary layer technique. Experiments have been carried out under perturbed conditions and results have shown that SMC performs well and remain stable and thus proves to robust controller for upper limb robotic manipulator.

scholarly journals ADAPTIVE SLIDING MODE CONTROL FOR BUILDING STRUCTURES USING MAGNETORHEOLOGICAL DAMPERS

2011 ◽  
Vol 14 (4) ◽  
pp. 92-105
Author(s):  
Hai Thanh Nguyen ◽  
Nghia Hoai Duong ◽  
Chuyen Quang Lam
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Lyapunov Theory ◽  
Adaptive Sliding Mode Control ◽  
Building Structures ◽  
Adaptive Sliding Mode ◽  
Mr Dampers ◽  
Mode Control ◽  
Indirect Control ◽  
The Stability

The adaptive sliding mode control for civil structures using Magnetorheological (MR) dampers is proposed for reducing the vibration of the building in this paper. Firstly, the indirect sliding mode control of the structures using these MR dampers is designed. Therefore, in order to solve the nonlinear problem generated by the indirect control, an adaptive law for sliding mode control (SMC) is applied to take into account the controller robustness. Secondly, the adaptive SMC is calculated for the stability of the system based on the Lyapunov theory. Finally, simulation results are shown to demonstrate the effectiveness of the proposed controller.

scholarly journals Proxy-Based Sliding Mode Vibration Control with an Adaptive Approximation Compensator for Euler-Bernoulli Smart Beams

2020 ◽  
Vol 53 (6) ◽  
pp. 825-834
Author(s):  
Hayder F.N. Al-Shuka
Keyword(s):  
Sliding Mode Control ◽  
Vibration Control ◽  
Sliding Mode ◽  
Lyapunov Theory ◽  
Pd Control ◽  
Adaptive Approximation ◽  
Mode Control ◽  
Sinusoidal Disturbance ◽  
The Stability ◽  
Modal Equation

Proxy-based sliding mode control PSMC is an improved version of PID control that combines the features of PID and sliding mode control SMC with continuously dynamic behaviour. However, the stability of the control architecture maybe not well addressed. Consequently, this work is focused on modification of the original version of the proxy-based sliding mode control PSMC by adding an adaptive approximation compensator AAC term for vibration control of an Euler-Bernoulli beam. The role of the AAC term is to compensate for unmodelled dynamics and make the stability proof more easily. The stability of the proposed control algorithm is systematically proved using Lyapunov theory. Multi-modal equation of motion is derived using the Galerkin method. The state variables of the multi-modal equation are expressed in terms of modal amplitudes that should be regulated via the proposed control system. The proposed control structure is implemented on a simply supported beam with two piezo-patches. The simulation experiments are performed using MATLAB/SIMULINK package. The locations of piezo-transducers are optimally placed on the beam. A detailed comparison study is implemented including three scenarios. Scenario 1 includes disturbing the smart beam while no feedback loop is established (open-loop system). In scenario 2, a PD controller is applied on the vibrating beam. Whereas, scenario 3 includes implementation of the PSMC+AAC. For all previously mentioned scenarios, two types of disturbances are applied separately: 1) an impulse force of 1 N peak and 1 s pulse width, and 2) a sinusoidal disturbance with 0.5 N amplitude and 20 Hz frequency. For impulse disturbance signals, the results show the superiority of the PSMC+AAC in comparison with the conventional PD control. Whereas, both the PSMC+ACC and the PD control work well in the case of a sinusoidal disturbance signal and the superiority of the PSMC is not clear.

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