Interference-free insertion of a solid body into a cavity

Abstract

The present method and apparatus determines an interference-free trajectory for fitting a moving solid body into a cavity, particularly where the body has a complex shape and tightly fits into the cavity. The method begins by describing the body surface with a finite set of body surface elements and the cavity surface with a finite set of cavity surface elements. Then a set of surface element pairs is determined. Each set comprises a body surface element and a corresponding cavity surface element. A neighborhood is a volume that contains the pair of surface elements but no other surface element pairs or parts of surface elements. Body motion constraints are developed for each pair. The constraints do not allow the body motion to cause the surface elements in the pair to interpenetrate or to leave their respective neighborhood. An incremental movement of the body, along a preferred direction, is then determined subject to the constraints. The body is moved the incremental amount and the process is repeated with a new set of pairs. Apparatus using the method can without interferences insert bodies into cavities or design and/or manufacture bodies and/or cavities with interference-free insertion trajectories. The invention has specific application to the design and insertion of prosthetic implants.