圆弧足被动行走机器人动力学参数影响研究

Research on the Influence of Dynamic Parameters of a Passive Walking Robot with Arc Feet

被动行走机器人运动特性主要取决于动力学参数的选择。为研究参数变化对机器人步态的影响,以圆弧足被动行走机器人为研究对象,利用拉格朗日方法建立动力学方程并进行了数值仿真。借助分岔理论研究了圆弧足半径、质心位置、转动惯量和斜坡倾角对机器人稳定步态的影响。采用正交扰动向量法求解被动行走机器人这种非光滑系统的李雅普诺夫指数,对分岔动力学进行了验证。结果表明:随着质心位置、转动惯量和斜坡倾角增大,机器人步态出现倍周期分岔现象,当圆弧足半径在特定区间内增大时机器人仍保持周期一步态,但足半径过度增大会导致步态失稳;另外,双参数研究中对圆弧足半径和质心位置联合作用下机器人稳定参数区间变化进行了分析,并且发现机器人步态呈现出逆倍周期分岔现象。该研究结果为未来双足步行机器人的优化设计和主动控制提供了重要参考。

The motion characteristics of passive walking robot mainly depend on the choice of dynamic parameters.In order to study the influence of parameter changes on the gait of the robot,a passive walking robot with arc feet is taken as the research object,the dynamic equation using Lagrange method is established and the numerical simulation is carried out.Based on bifurcation theory,the effects of arc foot radius,center of mass position,moment of inertia and slope angle on the stable gait of the robot are studied.The orthogonal perturbation vector method is used to solve the Lyapunov exponent of passive walking robot which is a non-smooth system and the bifurcation dynamics are verified.The results show that with the increase of center of mass position,moment of inertia and slope angle,period-doubling bifurcation occurs.When the arc foot radius increases in a certain range,the robot maintains a period-one gait,but when the foot radius increases excessively,the robot will become unstable.In addition,parameter ranges of stable robot walking when arc foot radius and center of mass position change are analyzed in the two-parameter study,and it is found that the gait of the robot presents the phenomenon of inverse period-doubling bifurcation.The research results provide important references for the optimal design and active control of biped walking robots in future.