Design And System Simulation Of Lower Limb Powered Exoskeleton Based On Head Position Control

This paper finds a ubiquitous phenomenon of head rotation by observing some daily behaviors: before the human body walks left,the head will turn to the left side in advance;before turning right,the head will turn to the right side in advance.Since the head rotation occurs before the walking steering,it is considered that the head turning motion can be used as a form of expression of the human body intention when walking.This paper designs a lower limb powered exoskeleton,which uses the head position of the human body to adjust the walking direction and speed of the lower limb powered exoskeleton in the assist mode.In this paper,a lower limb powered exoskeleton structure with amplifying effect on output torque is designed.The force position relationship,kinematics and dynamics are analyzed.The head rotation phenomenon when the human body is turning is deeply studied through experiments.Finally,a walking fuzzy control system based on head position adjustment is designed.First,the structure of the exoskeleton was designed.This paper proposes a three-level motion control idea.According to this control idea,an exoskeleton structure scheme with small weight,strong load capacity,large joint output torque and comfortable and flexible design is designed.Through the analysis of the dead center position of the hip and knee joint drive structure,the feasibility of the drive structure scheme is guaranteed.Strength analysis of parts in the exoskeleton ensures structural design reliability.Secondly,the force position relationship,kinematics and dynamics of exoskeleton are analyzed.Analyze the force position relationship between the hip and knee drive mechanism,establish the relationship between the joint angle and the position of the screw nut,and the relationship between the joint torque and the axial force of the screw nut,paving the way for the study of the following kinematics.A one-legged in-plane kinematics model and dynamics model with hip joints as the origin are established.The 12-degree-of-freedom kinematics model of the exoskeleton with the unilateral heel as the origin is established,which lays a foundation for the research of the motion control of the exoskeleton.Then,the head rotation phenomenon when the human body walks and turns is deeply studied.A human body motion parameter acquisition system is designed.The design acquisition experiment collects the motion parameters such as the axial angles of the humanhead and the torso when walking and steering.Design a data processing algorithm that not only filters out the fluctuations in the angle between the head and the waist during walking,but also maintains a fast response when steering.Observe the changes of the movement parameters of the head and waist during straight walking and steering,and analyze the relationship between the head direction and the walking direction,which lays a foundation for the control research of the lower limb powered exoskeleton robot based on the head position walking steering.Finally,a walking fuzzy control system based on head position control is designed.A head-direction fuzzy control system is designed for the relationship between the head direction and the walking direction when walking.The head position is used as the system input,and the walking direction of the exoskeleton robot is taken as the system output.A direction-walking fuzzy control system is designed.The walking direction of the exoskeleton robot is taken as the system input,and the heel coordinate and direction of the support leg of the exoskeleton robot are taken as the system output.Aiming at the problem of more interference information in the head position of the human body,an anti-interference head-direction fuzzy controller is designed.It can effectively filter out most of the interference pose information of the head.