Research On Redundant Motion Control Of Lower Limb Rehabilitation Robot

As Chinese society had already entered the aging period, the elderly people and thepatients were both increasing, rehabilitation robots were used in the field of rehabilitationtraining. The rehabilitation robot is a kind of medical robot, and could provide patients withsafe, stable and reliable operation. The rehabilitation robot that described in this thesis is anomni-wheeled robot and one of its wheels becomes a driven wheel because of losing control.Due to the driving force of the motor may get some disturbances, the driving velocity of thewheels may also get disturbance. The error and disturbance of the robot may increase. Therobot’s tracking performance, security and stability are influenced.(1) The kinematics and dynamics mathematical models of the lower limb rehabilitationrobot were established. Firstly, the structure of the lower limb rehabilitation robot wasanalyzed and researched. Secondly, the characteristics of the kinematics and dynamics wasresearched that based on the global coordinate system. The relevant kinematics and dynamicsmathematical models were established to solve the related problem between each velocity ofthe four wheels and the velocities of the pose coordinates.(2) The inverse kinematics of the lower limb rehabilitation robot was researched. Whenthe inverse kinematics model was transformed to the forward kinematics model, thetransformation of the forward and the reverse was involved. The four wheeled robot has betterflexibility and fault tolerance, because a four wheeled robot has one more degree of freedomthan the three wheeled robot. The better results were achieved by using redundant control. Dueto the particularity of four-wheel wheeled robot, the transformation of the matrix involved thegeneralized inverse matrix and there are15kinds of generalized inverse matrix. Thegeneralized inverse matrix of the kinematics was researched and designed in this thesis.(3) The controller of the lower limb rehabilitation robot was designed. The traditionalPID controller was applied widely, but there is also insufficient, such as need precise model.Firstly, the fuzzy control was analyzed and researched, and then the fuzzy PID controller thatcombining the fuzzy controller and PID controller was designed. Simulation was obtainedusing Matlab software, and the result proved that the designed fuzzy PID controller reducesthe errors and has a better rapidity. (4) The novel kinematics models of the lower limb rehabilitation robot were designed.The design of the generalized inverse matrix combined with the kinematics models of therobot, and then the novel kinematics models were established. After the novel kinematicsmodels was analyzed and researched, the different generalized inverse matrix and theappropriate parameters were selected according to different models. The novel kinematicsmodels were established to solve the problems that one of the wheels becomes a driven wheelor the driving velocity of the wheels may get disturbance. Finally, simulation was obtainedusing the Matlab software, and the feasibility of the design model was proved.