Automatic selection of fixture points for frictionless assemblies

During the assembly of a product, it is vital that the partially completed assembly be stable. If the assembly is unstable, then it must be fixtured to stabilize it before retrieving the next part or subassembly This paper presents a stability test and a new approach to automatically generating the positions of a small set of fixture elements (fixels) that will stabilize an assembly. The stability test and the fixel positioning approach consider both the translational and rotational degrees of freedom of each part. Since all the relevant mechanical constraints are linear functions of the contact force magnitudes and the components of the velocities of the parts, linear programming techniques can be used with great efficiency