ABSTRACT
We address the problem of computing immobilizing fixtures and grasps of three-dimensional objects, using simple fixturing devices and grippers with both discrete and continuous degrees of freedom. The proposed ap proach is based on the notion of second-order immo bility introduced by Rimon and Burdick [48, 4$, 50], which is used here to derive simple sufficient conditions for immobility and stability in the case of contacts be tween spherical locators and polyhedral objects. In turn, these conditions are the basis for efficient geometric al gorithms that enumerate all of the stable immobilizing fixtures and grasps of polyhedra that can be achieved by various types of fixturing devices and grippers. Prelim inary implementations of the proposed algorithms have been constructed, and examples are presented.
