Research On The Pneumatic Parallel Ankle Rehabilitation Robot

The ankle joint, which plays an important role in human’s daily life, is not onlythe largest load joint of human body but also the key joints of human lower limbmovement. At present, due to the increasing aging of the population, the rapiddevelopment of transportation and the accelerating rhythm of people’s life, ankleinjury is a common phenomenon in our daily life. Rehabilitation robot can helppatients with physical activity barriers to finish many kinds of rehabilitationexercises, and it is a new type of robots in recent years. With the using of anklerehabilitation robot, physicians can be liberated from heavy rehabilitation works,and it is also very easy to assess the rehabilitation effect, correct training plans, etc.Rehabilitation robot is sure to have a certain practical value and a good applicationprospect.Firstly, this paper analyzes the physical structure, the movement forms anddamage types of the ankle joint based on the knowledge of anatomy, rehabilitationmedicine and clinical medicine. In view of the ankle injury types and reasons, theankle rehabilitation treatment methods are discussed. The ankle movement formsare simplified. According to different rehabilitation stages of the ankle, threecontrol strategies are introduced. Moreover, the requests of the rehabilitation robotare put forward and the rehabilitation training target is determined.Secondly, the basic theories including the kinematics and dynamics of the6-DOF rehabilitation robot are analyzed. Then, the pneumatic position control systemmodel, the robot dynamics model based on SimMechanics and the whole pneumatic-mechanical robot model are built in Simulink with the powerful modeling andsimulating function of Matlab. Besides, the frequency characteristics, time-domaincharacteristics and workspace of the robot are analyzed.Thirdly, three control strategies including the trajectory tracking strategy, theimpedance control strategy and the ankle active movement control strategy areanalyzed according to the different stages of ankle rehabilitation. The simulationmodels are built and analyzed based on Matlab/Simulink. The effect of theimpedance control and the influences of the impedance controller parameters changes are analyzed. For ankle active motion control system, the surplus torque ofthe system is analyzed and be suppressed by adopting structure invariance principle.Finally, how ankle parameters change (mainly stiffness and damping) with theankle joint movements are analyzed. What’s more, simulation analysis of the actualankle rehabilitation training system based on the three above control strategies areconducted, and the results show that all the three control strategies are feasible andeffective.