On Exoskeleton Robot For Gait Rehabilitation

An exoskeleton robot for motor training in gait rehabilitation is in combination with the robot technology and the body weight supported treadmill training. When introduced into the gait rehabilitation after spinal cord injury, the exoskeleton robot performs with the characteristics of high accuracy, fast response and "tireless", and it is likely to avoid the drawbacks of the traditional body weight supported treadmill training. Meanwhile, the exoskeleton robot will help to train the patients as well as record the training data, free the doctors from the heavy physical work so that they can have more time to focus on the superior work such as rehabilitation training evaluation and making recovery plans. And then, the quality and efficiency of the rehabilitation training will be highly enhanced. Thus far, the exoskeleton robot has been a focus on the development of neuro-rehabilitation technique in the worldwide.The research subject on key technologies of the rehabilitation robot in gait training, which is sponsored by National High-Tech R & D Program, is undertaken by the Laboratory of Intelligent Machine and System at School of Mechatronics Engineering and Automation of Shanghai University. Some research works associated with the exoskeleton robot are described in this thesis, including mechanical design, system modeling, method of motion control, etc. They are described in detail as follows:Considering the patients'requirements and safety of gait training, the exoskeleton robot is designed combination of many technologies, such as ergonomics, bionics and mechanical design. Each leg of the exoskeleton robot has three degree of freedom at hip, knee and ankle joints. To drive flexion and extension movement of joints, a custom-designed electric linear actuator is adopted. A physical prototype of exoskeleton robot has been developed. Robot-in-charge and patient-in-charge modes are introduced on the principle of rehabilitation therapy and robot-assisted training. Using the Lagrange method, the mathematic model in robot-in-charge mode is given. In order to develop man-machine coupling between the trainer and the exoskeleton robot, dynamics equations of man-machine system in patient-in-charge mode is built based on the Newton-Euler approach.The computed torque control law with proportion-differential feedback is designed in robot-in-charge mode. Uncertain factors of dynamic model influencing the control algorithm are discussed and the convergence of the control method is proved in theory. To remove modeling error and improve trajectory tracking control effect, a compensating scheme on radial-basis-function neural network is presented. In patient-in-charge mode, a position-based impedance control approach is introduced. The relation between modeling error and impedance is analyzed theoretically.To develop the exoskeleton robot, a method based on virtual prototype and collaborative simulation is proposed. Solidworks, Adams and Matlab/Simulink are integrated to be used to establish united simulation platform for the exoskeleton robot. Kinematics and dynamics simulation of the exoskeleton robot, the trajectory tracking control laws are done in collaborative simulation platform. The results give important reference for mechanism optimization and motor selection, indicating that the proposed method can control and track the trajectory of the exoskeleton robot effectively.Through establishing a prototype of the exoskeleton robot, a series of training experiments are carried out, which demonstrate the functionality, safety and reliability of the exoskeleton robot. The results prove the feasibility of the exoskeleton robot system. But the exoskeleton robot still need be improved for human testing.The achievements of this thesis are summarized as follows:An actuated robot ankle joint applying to rehabilitation training may result in the complex structure of the exoskeleton robot and the difficulty of motion control which can be solved using multi-axis motion control system. The exoskeleton robot with the actuated ankle joint makes patients trained completely, in accord with the requirements of clinical practice.The dynamics model of the man-machine system walking on the treadmill in robot-in-charge mode is built. Based on the master-slave following control strategy, a computer torque control law with proportion-differential feedback and a compensating scheme based on radial basis function neural networks are designed to make up uncertain factors of the dynamic model and increase the ability of the trajectory tracking.Dynamics equations of the trainer and the exoskeleton robot are built respectively based on the Newton Euler approach. The decoupling relationship between the trainer and exoskeleton robot is found using man-machine Interaction Information. This provides theoretical foundation for developing dynamic control methods in patient-in-charge mode.The exoskeleton robot, one of key issues on rehabilitation robot in gait training, is developed deeply in this thesis. These works provide the necessary theoretical basis, experimental data and valuable research experience for development of rehabilitation robot in gait training. With improvement of the related technologies, some products on the rehabilitation robot are realized. This is of positive academic significance and practical importance to improve the quality of rehabilitation training.