Adaptive Direct Teaching Control With Variable Load Of Lower Limb Rehabilitation Robot

As the number of lower limbs dyskinesia patients caused by stroke is increasing year by year,the rehabilitation treatment of patients with lower rehabilitation robot has become a research hotspot.In this paper,the fourth generation of lower limb rehabilitation robot developed by the team is taken as the research object,an adaptive direct teaching function with variable load is studied.This function is composed of dragging teaching stage and replay stage,it can make lower limb rehabilitation robot provide the repetitive track rehabilitation training according to the teaching track of rehabilitation doctors.In this paper,the dynamic equation,direct teaching function with variable load control law,control system and experiment of the lower limb rehabilitation robot are studied.Firstly,in order to get more accurate dynamic equations of the lower limb rehabilitation robot,the joint flexibility caused by the harmonic reducers and torque sensors is considered in the establishment of the dynamic model.The Lagrange method was used to derive the dynamic equation of the lower limb rehabilitation robot considering joint flexibility,and the properties of the dynamic equation of the lower limb rehabilitation robot were analyzed,which lays the foundation for the later study of adaptive direct teaching function with variable load.Secondly,the influence of joint flexibility on lower limb rehabilitation robot is weakened by using the method of intermediate input variables.On this basis,the control law of the dragging teaching stage and the replay stage in the variable load adaptive direct teaching function is designed.Model reference adaptive control strategy is added to the designed control law to eliminate the influence of patient difference on control effect.The control law of dragging teaching stage and replay stage is simulated and verified by the Simscape toolbox in Matlab.Thirdly,in order to meet the high real-time requirements of the designed control law in the dragging teaching stage and replay stage,the control system of the lower limb rehabilitation robot with the flexible joint controller as the core is designed.The current loop control law of the flexible joint controller is designed by using vector control strategy and sliding film variable structure control strategy,and the current loop control law of the flexible joint controller is simulated and verified by Matlab.At the same time,the circuit design of the flexible joint controller is completed.Finally,the dynamic parameter values of the lower limb rehabilitation robot were obtained by the method of dynamic parameters identification based on experiments.On this basis,experimental was carried out on the direct teaching function with variable load,which verified the effectiveness of the designed control law and control system.