Kinematic methods for automated fixture reconfiguration planning

A kinematic method is developed to analyze the workholding condition by evaluating the motion stops corresponding to the reciprocal screw motions within a given fixture configuration. More significantly, the method can be used to compare the relative quality of two or more configurations in terms of the overall kinematic constraint. Graphically based methods are then developed which can be used to synthesize a fixture layout configuration for a given 3-D workpart geometric model. A CAD system is used to demonstrate the techniques for automated fixture layout planning. The results of this work have been applied directly to a set of modular fixture elements for sheet metal workparts. For simple geometries, the fixture configurations chosen with the motion stop method agree well with the intuitive choices an engineer would make. However, for complicated geometries, these methods provide analysis and synthesis solutions which would not otherwise be possible