Cam Mechanisms Reverse Engineering Based on Evolutionary Algorithms

Abstract

Cam follower mechanisms are widely used in automated manufacturing machinery to transform a rotary stationary motion into a more general required movement. Reverse engineering of cams has been studied, and some solutions based on different approaches have been identified in the literature. This article proposes an innovative method based on the use of an evolutionary algorithm for the identification of a law of motion that allows for approximating in the best way the motion or the sampled profile on the physical device. Starting from the acquired data, through a genetic algorithm, a representation of the movement (and therefore of the cam profile) is identified based on a type of motion law traditionally used for this purpose, i.e., the modified trapezoidal (better known as modified seven segments). With this method it is possible to estimate the coefficients of the parametric motion law, thus allowing the designer to further manipulate them according to the usual motion planning techniques. In a first phase, a study of the method based on simulations is carried out, considering sets of simulated experimental measures, obtained starting from different laws of motion, and verifying whether the developed genetic algorithm allows for identifying the original law or approximating one. For the computation of the objective function, the Euclidean norm and the Dynamic Time Warping (DTW) algorithm are compared. The performed analysis establishes in which situations each of them is more appropriate. Implementation of the method on experimental data validates its effectiveness.

Analytical, Numerical and Experimental Analysis of a Positive Displacement Cam Mechanism—A Case Study

“…The following types of cam mechanisms were studied concerning the methodologies for calculating the geometrical parameters and the profile curves for the cams: plane mechanisms with disk cams having external profiles or profiled grooves, with oscillating or translating followers, those having rollers or being flat-faced, and also spatial mechanisms with cylindrical cams. Tiboni et al [11] proposed the use of an evolutionary algorithm for the representation of the movement, and, therefore, of the cam profile, based on the modified trapezoidal motion law, also known as the modified seven segments. Faxin and Xianzhang [12] presented a software solution developed on the VB (Visual Basic language) platform for designing the moving tracks and the cam's profile in the case of a parallel combination of cam mechanisms.…”