Nonlinear dynamics investigation of contact force in a cam–follower system using the Lyapunov exponent parameter, power spectrum analysis, and Poincaré maps

Abstract

Abstract 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