Abstract
Rehabilitation robots are a new technology dedicated to the physiotherapy and assistance motion and has aroused great interest in the scientific community. These kinds of robots have shown a high potential in limiting the patient’s disability, increasing its functional movements and helping him/her in daily living activities. This technology is still an emerging area and suffers from many challenges like compliance control and human–robot collaboration. The main challenge addressed in this research is to ensure that the exoskeleton robot provides an appropriate compliance control that allows it to interact perfectly with humans. This article investigates a new compliant control based on a second-order sliding mode with adaptive-gain incorporating time delay estimation. The control uses human inverse kinematics to complete active rehabilitation protocols for an exoskeleton robot with unknown dynamics and unforeseen disturbances. The stability analysis is formulated and demonstrated based on Lyapunov function. An experimental physiotherapy session with three healthy subjects was set up to test the effectiveness of the proposed control, using virtual reality environment.
Highlights
Many types of injury such as structural defects, cerebral palsy, brain tumors, spinal injury, multiple sclerosis, or other neurological diseases can damage the human nervous system, which means loss of the functional capacity.[1,2,3] In paralyzed patients, maximum capacity can be restored through physical therapy applications and robotic devices.[1,2,3,4,5] The purpose of the physical therapy and the neural rehabilitation program is to help the patient achieve the best possible condition and to gain independence of his functions to minimize or to eventually eliminate the problems that might arise from the disease
Motivated by the previous analysis, we propose a new adaptive-gain second-order sliding mode control combined with time delay estimation (TDE).[31,32,33,34]
The new approach proposed in this research combines an adaptive-gain second-order sliding mode control and TDE, applied on the dynamic model of the exoskeleton robot presented in equation (2)
Summary
Many types of injury such as structural defects, cerebral palsy, brain tumors, spinal injury, multiple sclerosis, or other neurological diseases can damage the human nervous system, which means loss of the functional capacity.[1,2,3] In paralyzed patients, maximum capacity can be restored through physical therapy applications and robotic devices.[1,2,3,4,5] The purpose of the physical therapy and the neural rehabilitation program is to help the patient achieve the best possible condition and to gain independence of his functions to minimize or to eventually eliminate the problems that might arise from the disease. Despite the accuracy and robustness of second-order sliding mode control due to its potential to attenuate the undesired chattering dilemma.[30] the complicated mechanical structure of the robot and the variation of its parameters (due to the uncertainties function and unforeseen external forces due to the different subject’s characteristics) require a large switching gain to maintain the stability of the robot system, which again causes the chattering problem To overcome these limitations, we incorporate the second-order sliding mode control with TDE to achieve an accurate performance of the exoskeleton robot with unknown dynamics and external disturbances. Experimental and comparison results are shown in the fourth section; the conclusion is presented in fifth section
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
