Research On Human-Machine Compatibility Of Lower Limb Exoskeleton Robot

The human-machine compatibility is the characteristic that the lower limb exoskeleton robot fits the contour of the human body and the power output adapts to the characteristics of human motion.The purpose of this project is to design a lower limb exoskeleton robot,which can be worn in the legs of human body,enhance the flexibility of movement,improve the comfort of wearing,and have better human-computer compatibility.When the wearer is walking on flat ground and stairs,the exoskeleton robot of lower limbs can provide flexible assistance for the flexion and extension of hip joint and knee joint,alleviate the joint load of the wearer,and improve the movement efficiency.The main contents of this thesis are as follows:First,a walking experiment of human body in complex terrain is carried out to obtain the walking characteristics of human body.The maximum flexion angles of hip joint and knee joint are 21.74° and 52.38° respectively,the maximum extension angles are 13.71° and 1.16° respectively,and the maximum value of lateral quadriceps femoris is 49 N.The maximum flexion angles of hip and knee joint are 34.61° and 79.02° respectively in step terrain movement.The maximum flexion angles of medial quadriceps are 90 N walking up step and 35 N walking down.The maximum extension angle of hip joint is 17.82° walking up slope,3.42° walking down,and the maximum flexion angles of hip joint are 36 N and 53 N for hamstring and gluteus maximus respectively.Second,based on the characteristics of human-machine compatibility,three design schemes of lower limb exoskeleton robot are proposed.The optimal design scheme is determined by solving morphological matrix.Then draw the structure diagram of the lower limb exoskeleton robot,determine specific structure of the lower limb exoskeleton robot through kinematic and dynamic analysis,complete the selection of the driving module and design relevant accessories.Third,based on a human-computer cooperative control strategy,a new signal evaluation mode is established.According to the control structure of the lower limb exoskeleton robot,the control flow of the lower limb exoskeleton robot is designed.According to the motion characteristics of flat and step terrain,the judgment criteria of different motion terrain are established.Finally,a movement simulation analysis of the lower limb exoskeleton robot is carried out by using UG software.When lower limb exoskeleton robot moves on ground,the angular velocity range of hip and knee joints are-1.72 ～ 2.48rad/s and-5.42 ～ 5.13rad/s respectively,when lower limb exoskeleton robot moves in stairs,the torque range of hip and knee joints are-5.46～5.52N·m and-14.62～5.03N·m respectively.The approximate error between simulation results and theoretical results are less than 1%,which shows lower limb exoskeleton robot has acceptable human-machine compatibility.The finite element analysis of hip and knee joint’s net structures are carried out by using ANSYS.When lower limb exoskeleton robot moves on the ground,the maximum stresses of net structure of hip and knee joints are 0.03 MPa and 0.008 MPa respectively.When lower limb exoskeleton robot moves in stairs,the maximum stress of net structure of hip and knee joints are 0.035 MPa and 0.078 MPa respectively.The human-machine compatibility of lower limb exoskeleton robot can improve the design level,enhance the wearing comfort and increase the movement flexibility,which has important scientific significance,social value and application prospect.