Analysis And Experimental Study On Dynamic Parameter Matching Of Biped Passive Walking Robot

Compared with the traditional active biped walking robot,the passive biped walking robot has the advantages of simple structure and control,natural gait,and low energy consumption.This kind of purely passive walking robot does not need any motor drive input and its stable walking is completely determined by the initial conditions and parameters.To realize its stable walking,the study of dynamic parameter matching becomes a very important topic in the field of a passive walking robot.At present,most of the parameter studies of passive walking robots involve one-dimensional parameters or specific discrete parameter sets,and lack of research on the influence of parameter joint action,which is difficult to fully reflect the evolution information of passive gait,and few of them carry out parameter studies by directly collecting experimental data of prototype.In this paper,the mechanical model of a biped passive walking robot is firstly presented,and the moving process of the model is analyzed.The single-step motion of the robot is divided into two stages: swing and collision.The dynamic equation is established by using the Lagrange method and the law of conservation of angular momentum,and the equation is processed with dimensionless method.Secondly,the gait of the passive walking robot with fixed parameters is solved by using the standard fourth-order Runge-Kutta method,and the motion characteristics and energy changes in the periodic gait are analyzed in detail.The stable periodic gait of the robot is solved by using the Poincare section method and Runge-Kutta method with mixed step length.The effects of one-dimensional parameters,including arc foot radius,center of mass position,the moment of inertia,and slope angle,on the gait of the robot,are discussed.The Lyapunov exponent of the non-smooth system is calculated,and the bifurcation dynamics behavior is verified.Particularly,the abundant information of gait evolution in the two-dimensional parameter plane is described,and the effect of parameter combination on the gait of the robot is analyzed.Then,Solid Works software is used to design the robot simulation model with different parameters,and the models are imported into ADAMS.By establishing a reasonable simulation environment,the dynamics simulation of the model is carried out.According to the results of simulation analysis of the arc foot radius and slope angle change influence on robot movement characteristics.At the same time,by comparing the simulation results and theoretical curve,the theoretical analysis results of parameter variation are verified.Finally,a biped passive walking robot prototype with adjustable structure is designed,and a reliable control system of the walking experimental platform is built.To study the influence of the change of arc foot radius,the moment of inertia,and slope angle on the walking stability and motion characteristics of the robot,several groups of experiments are carried out via the prototype platform.On one hand,the proportion of the successful walking of the robot is calculated by mathematical-statistical method and the influence of parameter variation on the walking stability is evaluated.On the other hand,Qualisys Track Manager(QTM)software and four Oqus cameras are used to accurately capture the robot's motion trajectory and process the experimental data.The results show that the experimental curve is consistent with the theoretical curve,which well verifies the correctness of the theoretical and simulation analysis.