Research On Control Technology Of Two Degrees Of Freedom Exoskeleton Robot

The lower extremity exoskeleton robot is a "wearable" mechatronics device connected in parallel with the human body.It can reduce the wearer’s consumption during exercise,assist the wearer in walking and enhance its weight-bearing ability.Exoskeleton robots have important research significance and social needs in military,civil and human limb rehabilitation,etc.A hot spot in the field.The lower extremity exoskeleton robot is used in the field of medical rehabilitation and can help patients with hemiplegia caused by stroke and central nerve injury to carry out rehabilitation training.The main technical challenges include light and reliable mechanical structure,real-time tracking of gait,and accurate stability.In this paper,by studying the mechanism of human lower limb movement,a two-degree-of-freedom lower extremity rehabilitation exoskeleton robot based on a disc motor was developed,kinematics and dynamics analysis was performed,the control strategy research of exoskeleton gait tracking was completed,and the design of the planning control system was completed.Through the combination of simulation analysis and physical prototype test,the effectiveness of the control technology is verified.The main work of the paper includes:(1)A two-degree-of-freedom lower limb rehabilitation exoskeleton structure based on a disc motor is proposed.By studying the movement characteristics and movement mechanism of the human lower limbs,the gait curve of the human body during walking was collected.According to the design requirements of the lower extremity exoskeleton obtained based on actual needs,on the basis of ensuring comfort and safety,a disc motor is used as the driving mechanism to design a lower extremity rehabilitation exoskeleton that includes two degrees of freedom of the hip and knee robot.(2)Kinematics and dynamics analysis of the lower extremity rehabilitation exoskeleton were carried out.The relationship between the joint angle of exoskeleton and the position and posture of the connecting rod end was analyzed by D-H parameter method.The Lagrange mechanics method was used to study the relationship between joint force / moment and human body motion position,and the dynamic model of the designed two-degree-of-freedom exoskeleton robot was established.(3)A passive control strategy for position tracking is proposed.Aiming at the problem of large external disturbances,an auto-disturbance control method is proposed through the established exoskeleton robot dynamics model.In Simulink,the tracking simulation of the normal gait curve and the tracking simulation of the gait curve under disturbance were carried out for auto disturbance rejection control and PID control,respectively.Simulation results show that,compared with traditional PID control,auto disturbance rejection control tracking is stable and has better anti-jamming capability.(4)A set of experimental prototypes of lower extremity rehabilitation exoskeleton based on disc motor were developed.Experiments were conducted on exoskeleton movement under auto-disturbance control strategy and exoskeleton movement when sending position information directly to the disc motor.The effectiveness of the auto disturbance rejection control strategy is verified.