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圣地亚哥州立大学LS Yousuf：Lyapunov指数、功率谱分析和Poincaré图的凸轮从动件系统接触力非线性动力

已有 687 次阅读 2023-8-29 15:35 |个人分类:IJMSD|系统分类:论文交流

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仿生四足机器人(bionic quadruped robot)是机器人研究的重要方向之一，因其灵活度高、环境适应力强、稳定性好，故在物资运输、工程勘探、抢险救援、军事察打等领域具有广阔应用前景。通过连杆机构将凸轮-从动件系统应用于仿生四足机器人，在从动装置最末端使用多减振器（弹簧-阻尼-质量）系统，能有效改善机器人动态性能，并减小凸轮与从动装置之间的分离高度。

美国圣地亚哥州立大学Louay S. Yousuf助理教授在《国际机械系统动力学学报（英文）》(International Journal of Mechanical System Dynamics, IJMSD)发表“Lyapunov指数、功率谱分析和Poincaré图的凸轮从动件系统接触力非线性动力学分析”研究论文。该文采用最大Lyapunov指数、快速傅里叶变换功率密度函数和从动装置非线性动力学现象产生的Poinaré图来检测凸轮与从动装置之间的分离情况。针对不同的凸轮速度和不同从动导引件的内部距离，研究了凸轮与从动装置之间的分离。研究结果表明，当凸轮和从动件永久接触时，没有势能损失，也没有冲击或恢复；而存在分离时，凸轮与从动件之间的分离高度会随着恢复系数的增加而增加。该研究为将凸轮-从动件系统应用于仿生四足机器人提供了理论指导和实验参考。

The aim of this article is to detect the detachment between the cam and the follower using the largest Lyapunov exponent parameter, the power density function of fast Fourier transform, and Poinaré maps due to the nonlinear dynamics phenomenon of the follower. The detachment between the cam and the follower was investigated for different cam speeds and different internal distances of the follower guide from inside. This study focuses on the use of the cam–follower system with a bionic quadruped robot through a linkage mechanism. Multishock absorber (spring–damper–mass) systems at the very end of the follower were used to improve the dynamic performance and to reduce the detachment between the cam and the follower. The SolidWorks program was used in the numerical solution, while a high-speed camera at the foreground of the OPTOTRAK 30/20 equipment was used to identify the follower position. The friction and impact were considered between the cam and the follower and between the follower and its guide. In general, when the cam and the follower are in permanent contact, there is no loss in potential energy, and no impact or restitution. The detachment between the cam and the follower increases with increasing coefficient of restitution in the presence of the impact.

Keywords:

nonlinear dynamics,

Lyapunov exponent,

non-periodic motion,

contact force

DOI: 10.1002/msd2.12025

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https://onlinelibrary.wiley.com/doi/10.1002/msd2.12025

Cite this article: Yousuf LS. Nonlinear dynamics investigation of contact force in a cam-follower system using the Lyapunov exponent parameter, power spectrum analysis, and Poincaré maps. Int J Mech Syst Dyn. 2022;2(2):214-230.

该文亮点：

采用最大Lyapunov指数、快速傅里叶变换功率密度函数和从动装置非线性动力学现象产生的Poinaré图来检测凸轮与从动装置之间的分离；
在从动装置最末端使用多减振器（弹簧-阻尼-质量）系统，以改善机构的动态性能，并减小凸轮和从动装置之间的分离高度；
考虑了凸轮与从动装置之间以及从动装置与其导引件之间的摩擦和冲击；
在OPTOTRAK30/20设备前台使用高速相机进行了实验测试。

Highlights:

The detachment between the cam and the follower was detected using the largest Lyapunov exponent parameter, the power density function using FFT, and Poincaré maps due to the nonlinear dynamics phenomenon of the follower.
Multishock absorber (spring–damper–mass) systems at the very end of the follower were used to improve the dynamic performance and to reduce the detachment height between the cam and the follower.
Friction and impact were considered between the cam and the follower and between the follower and its guides.
The experimental test was carried out using a high-speed camera at the foreground of the OPTOTRAK 30/20 equipment.

作者简介

Dr. Louay S. Yousuf A Visiting Assistant Professor at San Diego State University for one academic year in the Department of Mechanical Engineering. He received his Ph.D. from the University of Baghdad, Baghdad, Iraq and was a Postdoctoral Fellow at the Mechanical Engineering Department, University of Auburn, Alabama before joining San Diego State University. His research interests include non-linear dynamics of cam and follower, composite materials, finite element method, vibrations, and experimental stress analysis.

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