Research On Motion Analysis And Stability Control Of Half-rotation Walking Mechanism

At present,the motion system mainly includes legged-type,wheeled-type,crawler-type,etc.However,there are still many problems in the existing motion systems,so the new type of motion system has received more and more attention.Based on a half-rotation mechanism,two kinds of self-balance walking mechanism are proposed.This paper introduces the origin of the half-rotation mechanism and its structural characteristics,two different kind of self-balance configurations(mobile and swing)for half-rotation walking mechanism are proposed.The balance mechanism is the key to the design of half-rotation walking mechanism.Combined the vector velocity method with D-H method,a kinematics modeling and analysis method for the half-rotation walking mechanism is proposed in the precondition of there no slipping between the foot and ground.According to the characteristics of the walking mechanism,the vector motion equation(combined with the D-H method)is used to establish the transformation matrix among the components,the center coordinate system of the mechanism and the global coordinate system.The kinematics expressions of the two kinds of self-balance mechanisms are unified,and the kinematic characteristics of the key points such as position vector,angular velocity vector,and linear velocity vector are deduced.Based on the Lagrangian method,the dynamic modeling of half-rotation walking mechanism is performed.The movement process of the mechanism is divided into quadruped support and biped support phases.The Lagrange dynamics modeling of the biped support phase is established on the basis of simplification of system.The swing self-balance configuration of the walking mechanism is taken as an example of the deduction of dynamic model expression.A method of stability evaluation and a strategy of walking stability are proposed to analyzing the stability of motion of half-rotation walking mechanism,then the theoretical derivation and simulation verification are proceeded.The stability pyramid method is proposed to solve the motion stability problem of the mobile system.The two cases with only gravity action and external force disturbance are analyzed respectively,and the analytical expression of the minimum stability angle of the mechanism is obtained.In consideration of working environment and structural characteristics of the half-rotation walking mechanism,the stability pyramid method was simplified to the stability triangle.The strategy of walking stability is proposed to keep obtain the maximum value of the minimum stability angle in motion of the walking mechanism,and a corresponding theoretical derivation is performed to obtain the movement process of the balance mechanism(mobile and swing configuration).The validity of the strategy of walking stability was verified by simulation,and the stability of the walking mechanism was evaluated by the method of stability evaluation proposed.