Abstract: In a number of 3d applications and especially in Computer Aided Design (CAD), the accuracy of the selection process is important for subsequent operations. In this paper, we propose a mathematical model to manage haptic selection of topological entities (vertices, edges, faces...) used in CAD. We have developed an analytical expression with a generic and unified representation based on potential fields. The result is a simplified model for software implementation. Moreover, these functions introduce a smooth, accurate and stable force profile.