含间隙并联腿步行机器人的固有频率分析

Natural Frequency Analysis of a Parallel Legged Walking Robot with Clearance

针对步行机器人运行中出现振动与关节异响这一现象,采用动力学方法模拟运动副间隙模型的接触状态,分析了含间隙步行机器人的固有频率,避免了计算模态分析方法在仿真分析时会忽略非线性因素的问题。通过瞬态动力学仿真,计算出含间隙步行机器人的位移响应,再经过傅里叶变换,得到频率响应曲线,曲线峰值对应频率即为含间隙步行机器人的固有频率。仿真结果表明,关节间隙的存在会降低步行机器人的各阶固有频率,但间隙不会影响模态振型,1阶振型均为平台与支腿沿X轴的摇摆振动,2阶振型与1阶振型正交,3阶振型均为平台与支腿沿Z轴的扭转振动。

Aiming at the phenomenon of vibration and abnormal joint response in the operation of walking robot,the dynamics method is adopted to simulate the contact state of the clearance model of the moving pair,and the natural frequency of the walking robot with clearance is analyzed,avoiding the problem that the nonlinear factors are ignored in the simulation analysis of the computational modal analysis method.With the help of transient dynamics simulation,the displacement response of the walking robot with clearance is calculated,and then through the Fourier transform,the frequency response curve is obtained,the corresponding frequency of the curve peak is the natural frequency of the walking robot with clearance.The existence of joint clearance can reduce the natural frequencies of the walking robot,but the clearance does not affect the mode shapes.The firstorder mode is the sway vibration of the platform and the support leg along the X-axis,the second-order mode is orthogonal to the first-order mode,and the third-order mode is the torsional vibration of the platform and the support leg along the Z-axis.