Particle swarm optimization for the evaluation of cross-section contour error of variation elliptical piston skirt

With the rapid development of internal combustion engines (ICE) industry, the cross-section contour of variation elliptical piston skirt is widely used in order to achieve better mechanical and thermodynamics performances which the cross-section elliptic degree is diverse in the highness direction and the axis section contour is convex curve. Because of its complex form its geometrical precision evaluation is a difficult problem. Particle swarm optimization (PSO) that is based on two fundamental disciplines (social science and computer science) is proposed to implement the minimum zone evaluation of the cross-section contour error of variation elliptical piston skirt and the particle´ velocity is modified by constriction factor approach. Then, the design formula of the cross-section contour of variation elliptical piston is given and its objective function calculation approach using PSO to solve the minimum zone error of cross-section contour is developed which conforms to the ISO/1101 standard. Finally, the experimental results evaluated by PSO, the least square method (LSM) and improved genetic algorithm (IGA) confirm the effectiveness of PSO and it improves the cross-section contour error evaluation accuracy of variation elliptical piston skirt.