Design And Research Of A Parallel Mechanism For Lower-limb Rehabilitation

Driven by the requirements of the innovation of lower-limb rehabilitation robots,this thesis proposes a new foot-plate-based lower-limb rehabilitation robot which can simulate the walking path,and focuses on the concept design,kinematics optimization and scale synthesis,virtual prototype simulation and control scheme design of 3-DOF foot-pedal parallel rehabilitation mechanism.The following works have been accomplished.(1)According to the requirements of the design trajectory of the lower-limb rehabilitation training robots,the kinematic model of the lower limb is established,the movement track of the foot center on the sagittal plane and the angle curve of the foot attitude are obtained when the human body is walking.And then the function expressions of the movement track of the foot center and the angle of the foot attitude are obtained by using the function curve fitting,which provides the input for the design of the foot-plate-based rehabilitation robot.(2)Based on the movement track of human walking and the design requirements of lower-limb rehabilitation mechanism,this thesis proposes a redundantly actuated pedal-type lower-limb rehabilitation robot which can simulate the walking track and the foot attitude angle.On this basis,the 3-DOF foot-pedal parallel mechanism driven by flexible redundancy is studied,and the detailed design,position and speed analysis have been completed.The generalized Jacobian matrix is obtained,which lays the foundation for the following kinematics optimization and scale synthesis.(3)A new evaluation method for the force/motion transmissibility of redundantly actuated parallel mechanism is proposed by the redundantly actuated parallel mechanism is investigated via four individual cases without actuation redundancy.In addition,genetic algorithm is used to optimize the kinematics of the parallel mechanism,and the influence of a single design variable on the kinematic performance of the mechanism is analyzed.The results show that the optimized foot-plate-based parallel mechanism has good kinematic performance.(4)The virtual prototype model of the foot-plate-based rehabilitation parallel robot is established with the aid of ADAMS,and the inverse kinematics simulation of the foot center track,the inside/outside movement,the plantar/dorsiflexion movement is completed.The kinematic performance of the mechanism is comprehensively evaluated by confirming the kinematic state and interference between the components and the hinge.The design rationality of the foot-plate-based rehabilitation parallel robot is verified.On this basis,the control scheme of the robot is put forward,the selection of control elements and the design of pneumatic circuit are completed,which lays the foundation for the design and construction of the subsequent whole control system.The research on kinematics optimization and simulation in this thesis is of great significance to improve the kinematics performance and kinematics simulation of the foot-plate-based parallel mechanism.