The Input And Output Linearization Tracking Control Of Omnidirectional Rehabilitative Training Walker

Due to the serious aging population problem, patients suffering from physical injury and walking disorders increased year by year, the development of rehabilitation walking training robot is very necessary. The rehabilitation walking training robot is a typical multi variable, strong coupling nonlinear system. On the one hand, the strong coupling problem between the X axis, the Y axis and the direction angle of the track in the tracking process is present. On the other hand, there are friction, parameter changes, load changes and other uncertainties. It is difficult to obtain accurate tracking results for the rehabilitation walking training robot. At present,there are a lot of researches on the trajectory tracking of rehabilitation walking training robot,but ignore the speed tracking, and the speed tracking can achieve the patient’s exercise intensity, it has the vital significance to the walk ability recovery. In this paper, the input and output linearization method is used, to solve the speed and trajectory tracking problem of the omnidirectional rehabilitative training walker.Based on the structure of the omnidirectional rehabilitative training walker, using the method of input and output linearization, the decoupling state equation of the four wheels’ speed and its driving torque is derived by analyzing the kinematics and dynamics model of the omnidirectional rehabilitative training walker; Design speed tracking controller, achieve decoupling control for each driving wheel speed; Speed controller combined with nonlinear feedback control law, has realized the trajectory tracking of the omnidirectional rehabilitative training walker; Simulation experiments verify the proposed tracking control algorithm and compared with the traditional tracking control, the method meets both trajectory tracking and speed tracking.For the problem that various uncertainties and external unknown disturbance have great influences on the omnidirectional rehabilitative training walker, a disturbance observer was designed, which can observe uncertainties and external disturbances online; the observe digits were used to design a kind of tracking controller, the system was proven to be asymptotically stable by using the constructed Lyapunov function. The simulation results show that under the uncertainty disturbance, the proposed nonlinear disturbance observer and feedback linearization method can simultaneously realize the speed tracking and trajectory tracking.