Research On Design And Control Strategy Of The Lower Limb Rehabilitation Robots

Lower limb rehabilitation robot is a product to help the patients who have movement disorder caused by the neurological disorders such as stroke to regain movement ability. The incidence of cerebrovascular diseases such as stroke increased year by year, which leads to the increasing number of people with lower limb movement disorders. At the same time, the curative effect of rehabilitation robot has been confirmed, and the lower limb rehabilitation robot has attracted high attention of the researchers. The author and other members of the team manufactured a lower limb rehabilitation robot, including its mechanism design and control strategy research. The main contents are summarized as follows:This paper first studied the recovery mechanism, which provides theoretical for the design of the robot. According to the human lower extremity movement mechanism and Lower limbs parameters, there are two aspects needed to be considered in developing the robot, that is, degrees of freedom and height compatibility requirements. Based on these, a robot with two legs and a seat is designed. And each leg has 3 DOF. There is also length regulating mechanism in this robot. Furthermore, the motor selection is completed and the prototype is built.To set up the forward and inverse kinematics model of the l ower limb rehabilitation robot, Denavit-Hartenberg Method is applied in the analysis. The robot’s motion space is got, which could ensure the safety of user in the rehabilitation training. Then co-simulation between ADAMS and MATLAB is performed to verify the accuracies. The corresponding kinetic models are constructed using the Lagrange method. And to verify the correctness of the model, the ADAMS-based simulation is performed. Kinematics and dynamics analysis offer the theoretical basis for the trajectory planning and control strategy research.This paper studied the control strategy, including passive and active rehabilitation control methods. In order to realize the trajectory tracking, the control method based on the calculation of the torque is adopted in the passive training mode. Considering the modeling error and the disturbances, the paper designed an adaptive robust controller and proved the stability by using the Lyapunov stability theory. Then, ADAMS-based simulation are performed to verify the validity. Impedance control strategy is adapted to the active training, which could realize the force tracking. The paper proved the feasibility of impedance control strategy by ADAMS and MATLAB joint simulation. And also figured out the influence of impedance parameters on the system.The experimental platform of the Lower limb rehabilitation robot is built. Then the software and hardware of the robot are test to ensure the following work could be completed smoothly. The paper obtained the normal walking gait by using Open Sim software, and used MATLAB for curve fitting. Furthermore, a series of experiments are conducted, including passive training based on the trajectory tracking and active training based on impedance control method. The experimental results show the rationality of the structure and the correctness of and control strategy.