康复机器人准零刚度隔振特性分析与实验

为了解决康复机器人低频振动对人体的影响问题,提出并设计一种具有准零刚度特性的新型被动隔振机构,它由两个对称的具有负刚度特性的拉伸弹簧并联一个线性正刚度弹簧实现。首先,通过静力学特性,建立此隔振机构的力-位移和刚度-位移关系式,得出机构在静态平衡位置处具有准零刚度特性的参数条件;其次,通过动力学特性,建立其分别在简谐力和简谐位移激励下的非线性微分动力学方程,采用谐波平衡法分析机构参数与激励对系统力传递率、位移传递率的影响;最后,通过实验验证在有、无负刚度情况下,输入与输出的曲线。结果表明,在有负刚度机构的情况下,隔振系统具有一定范围的准零刚度特性,且低频隔振性能较好,达到了高静态、低动态刚度的效果。本研究对机器人低频隔振具有创新性和指导意义。

Analysis and Experimental Study on Quasi-Zero-Stiffness Vibration Lsolation Characteristics of Rehabilitation Robot

In this paper, a novel type of passive vibration isolation mechanism with quasi- zero- stiffness is proposed and designed, in order to solve the problem of low frequency vibration of rehabilitation robot. It is achieved by two symmetrical tension springs with a negative stiffness characteristic in parallel with a linear positive stiffness spring. Through the study of static characteristics,the relationship between the force displacement and the stiffness displacement of the vibration isolation mechanism isestablished, it is concluded that the parameters of the mechanism have quasi-zero-stiffness characteristics at the equilibrium position. The dynamic characteristics, nonlinear dynamic equations in harmonic power and the harmonic displacement excitation are studied, respectively. The influence of mechanism parameters and the excitation on the system force transfer rate and the displacement transfer rate are analyzed using a harmonic balance method. Finally, the curves of the input and output are compared with or without the negative stiffness through experiments. The results show that in the case of negative stiffness mechanism, the vibration isolation system has a certain range of quasi-zero-stiffness characteristics and the low frequency vibration isolation performance is better, which can achieve the effect of high static and low dynamic stiffness. It is innovative and instructive for the low frequency vibration isolation of robot.