| To meet the needs of reconfigurable ankle rehabilitation robot,a 3-(R)RPS parallel metamorphic mechanism with three ankle rehabilitation motion modes is proposed,and its mechanism configuration synthesis and analysis,kinematics analysis,work spatial analysis and kinematics simulation analysis verification are studied.The main research content is as follows:(1)A 3-(R)RPS parallel metamorphic mechanism with three ankle rehabilitation motion modes is proposed to meet the requirements of reconfigurable ankle rehabilitation robots.We studied the types of sports injuries to the human ankle joint and the rehabilitation mechanisms during different rehabilitation stages,and proposed a 3-(R)RPS parallel metamorphic mechanism design scheme for ankle joint injury patients with different rehabilitation requirements during different rehabilitation stages.The overall cellular structure design of a rehabilitation robot was completed based on a 3-(R)RPS spatial parallel cellular mechanism.(2)Based on geometric algebra,the configuration synthesis and analysis of3-(R)RPS parallel metamorphic mechanism were completed.Based on geometric algebra,taking the axis direction of the rotation pair as a variable,the unified expression of the mechanism’s motion space is obtained,and three metamorphic configurations with specific motion forms are synthesized,which can meet the rehabilitation needs of different ankle rehabilitation training stages.Compared with the traditional screw theory method,the method of geometric algebra is more concise and clear in the description of rigid body motion,which can avoid the matrix operation of the traditional method and the discrimination of linear correlation of related vectors,and can directly obtain the symbolic analytical expression of configuration synthesis of parallel metamorphic mechanisms with intuitive geometric interpretation.(3)The kinematics analysis and simulation verification of three specific3-(R)RPS parallel metamorphic mechanisms were completed.Under the constraints of the length of the branch chain and the rotation angle of the kinematic pair,the kinematics analysis and the work spatial analysis of the 3-(R)RPS parallel metamorphic mechanism were solved,including the attitude deflection angle of the moving platform and the offset of the moving platform center point.The results show that when the rotational axis of the low degree of freedom 3-(R)RPS parallel ankle rehabilitation robot is determined,the change in member length is one-to-one mapping relationship with the motion parameters of the mechanism’s moving platform,which is helpful for trajectory planning and control of the center point of the moving platform.At the same time,the kinematics simulation of the mechanism was carried out through ADAMS,and the kinematic characteristics of the robot’s moving platform were analyzed.Compared with the results obtained before,the correctness and feasibility of the established kinematics model were proved. |
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