Design And Research On The Hybrid Mechanism Of Ankle Rehabilitation Robot

With the extending of the robot technologies to the medical treatment field, the traditional rehabilitation ankle treatment is more gradually depended on the robot assistant. The researches on the ankle rehabilitation robot have become an important filed at home and abroad. The ankle rehabilitation robot is a complex interdisciplinary field. So the development of ankle rehabilitation robot requires not only the actual needed for medical rehabilitation treatment on ankle, but also innovative mechanism design of robot. In this dissertation, a novel hybrid mechanism of ankle rehabilitation robot is proposed, which is based on the ankle exercise therapy, the ankle kinematics analysis, and the characteristics of ankle rehabilitation equipments. The kinematic characteristics of the mechanism and the ankle motion of the ankle rehabilitation mannequin derived by the mechanism are respectively researched by simulation system. The main research contents are as follows.First of all, ankle rehabilitation exercise therapy is introduced. According to the fundamental type of ankle motion and the anatomy of the ankle, a two-axis motion model of ankle is established. The coordinate transformation matrix and posture equation of this model are given, then the movement relationship between the ankle and the foot is discussed. A three-axis ankle motion model based on the two-axis ankle model is developed.A novel hybrid redundant mechanism for ankle rehabilitation is proposed on the basis of the analysis and comparison for various kinds of ankle rehabilitation equipments. The mechanism with three degrees of freedom (DOF) is composed of three parts, including the redundant parallel mechanism with two DOF, the series mechanism with one DOF and the exoskeleton mechanism. This proposed hybrid mechanism has the advantages of stronger loads carrying ability and stiffness, excellent controllability, and the center of rotation near to the center of the ankle rotation.The mathematical model of the hybrid mechanism is put forwards. According to the mathematical model, the inverse and forward kinematics solutions are deduced. The relationship between minute movement and mechanism velocity is found by Jacobin matrix of velocity. Constraints parameters of the rotation workspace like the angle of point contact higher pair, the rod length, and the ball-end sliding distance, are discussed.Finally, the virtual prototype is built up for motion simulation in the Motion module. Ankle rehabilitation mannequin system is completed, and the simulation experiment of ankle motion which is derived by the hybrid mechanism is tested in the system.