# Study of Fault Identification of Clearance in Cam Mechanism
## 1 Introduction  
Much research on the profile of the cam mechanism has been conducted, changing the base circle radius, the eccentricity of the cam, and other parameters to obtain the required motion conversion and energy output. Moreover, optimizing the parameter settings further optimizes the cam mechanism's achievable functions. At present, this design concept has been widely used in the fields of transportation and aerospace. Through the study of the parabolic-cam-roller-quasi-zero-stiffness (PCR-QZS) isolator and the derivation of the theoretical formula, the conditions under which the parabolic cam roller (PCR) is superior to the circular cam roller (CCR) are obtained. Finally, a vibration isolator with a lower stiffness and transfer coefficient on a broader area near the equilibrium position is achieved [1]. The idea has gradually begun to prevail, of which followers are applying a multi-degree-of-freedom system to suppress the nonlinear dynamic motion. This system includes adding a spring-damping system at the end of the mechanism to turn the system into a multi-degree-of-freedom system, and using a fast Fourier transform through an infrared camera to reduce the corresponding frequency and peaks of the roller follower nonlinearity [2]. Based on the three-involute profile of the cam, the gap between the roller and the guide rail, the contact position of the roller and the cam curve groove, the dynamic change between the cam and the square groove key, the change in the Lyapunov exponent, and, from the rigid body, the change in contact stress are analyzed from a dynamic point of view. The Newton-Euler variance is used for analytical calculation. Finally, it is concluded that, the greater the contact stress, the greater the Lyapunov exponent and the greater the bending deflection value [3]. By studying the influence of guideway size and cam,angular velocity changes in the nonlinear dynamic response of the system, power spectrum analysis, phase plane mapping, and maximum Lyapunov exponent parameters are used to study the periodic motion of non-followers. Finally, the nonlinear response peaks of the roller follower at the four positions of 0\({}^{\circ}\), 90\({}^{\circ}\), 180\({}^{\circ}\), and 270\({}^{\circ}\)[4] are investigated. Multiple degrees of freedom (spring-damper system) are added at the end of the follower stem, and the peak of nonlinear response is reduced by 20.89%, 47.76%, 58.2%, and 67.16%, respectively [5]. In addition, the optimized design structure of the intermediate connection of three rollers is added between the cam and the typical follower, which can generate multiple contact points between the cam and the follower at any time. Experiments show that the contact stress is 30-47% lower than that of the traditional system [6]. In order to investigate the nonlinear dynamic effect of assembly clearance on the system when recoiled, [PERSON] et al. from NUC of China conducted a dynamic analysis of the main roller from the perspective of system dynamics and deduced the necessary conditions for pure rolling when the main roller suddenly reversed [7]. In order to study the influence of the contact load on the bending deformation of the cam profile, the bending deflection of the disc cam with the roller follower was analyzed under a constant angular velocity of the cam. Solidworks and Ansys software were used to measure the follower's deflection. The cam profile's dynamic response and bending deformation were studied and analyzed. Finally, the bending deflections of path 1, path 2, and path 3 were reduced by 73.425%, 85.925%, and 61.467%, respectively [8]. Another hot spot in this field in recent years has been the analysis and life prediction of the lubricating environment of the cam-roller follower system.