CAD/CAM of Jaws for Robot Grippers

Abstract

ABSTRACT Scissors and tongs- type grippers are two of the simplest and most rugged categories of mechanical end-effectors available. A method is investigated which enables them to pick up cylindrical objects of different diameters concentrically, a feature normally possessed only by the more complex and less durable parallel-closure gripping mechanisms. The proposed method involves fitting special jaws with curved profiles to the grippers. The paper begins with a derivation of the basic equations describing the jaw profiles. This is followed by an analysis of the geometrical parameters which govern their overall dimensions and a discussion of how these parameters should be selected to achieve compact jaw designs. Other topics studied in the paper are the systematic approximation of the mathematically-exact profiles derived in earlier sections with simpler curves to facilitate their machining and the design of jaws to attain kinematically-accurate three-point gripping. Finally, an interactive CAD/CAM software package developed to automate the design and manufacture of the jaws is presented.