Research On Position And Attitude Control System Of Gait Trainer

With the rapid development of society and the progress of science and technology, now,the quality requirements of people's life are also increasing. In this context, the gait trainer came into being and played an increasingly important role in the fields of medical rehabilitation, sports training, ergonomics, aerospace and others. In this paper, the research on position and attitude control system of gait trainer focused on the following aspects:Firstly, the overall scheme on the basis of functional requirements and performance analysis of the gait trainer was made. Then the model of kinematics analysis of the mechanism based on closed-loop vector method was established, and its forward and inverse kinematics equations was derived. Using MatLab software calculate the movement space of the end effectors to verify the feasibility of the overall scheme.Secondly, the rigid body model of human lower limb movement system in the sagittal plane was established based on the theory of human biomechanics. And according to the model derive the equivalent homogeneous transformation matrix of one centre of the foot relative to the other, then the position and attitude equations of human lower limb movement system based on the study of gait cycle was solved. After that, the gait experiments in walking,upstairs, downstairs mode was conducted with the help of FAB system, the measurement data was introduced into the kinematics equations to calculate and fit the gait trajectory of the relative mode. Then loading the planned trajectory into the inverse kinematic model of the mechanism to calculate the input values of the related joint motion, and planning the motion of every movement joint. After the semi-physical simulation model based on Simulink was established, and the SimMechanics simulation model analysis based on the displacement and angle of rotation input from motion planning was carries on to verify the correctness of the established model.In addition, the dynamics model of the mechanism based on simultaneous constraint method was established, and the simulation and analysis of the dynamic characteristics of the mechanisms based on Simulink toolbox as the basis of the control system. Three control strategies have been proposed: passive motion control strategy, trajectory tracking control strategy, compliance control strategy. According to PID control principle, the controller was designed to control the motor to achieve the corresponding control strategy. The motor control model is established to study its response characteristics in no-load and load conditions.Finally, the prototype system debugging was completed to detect whether its performance meets the requirements. The experimental platform was set up to carry out semi-physical simulation experiment based on dSPACE. Through the analysis of the experimental datas from different training modes, which verified the rationality of the control strategy and evaluated the actual performance of the prototype.