On the motion of oblique bevel geared robot wrists

In this article, we show that the principle of superposition can be applied for analyzing the spatial motion of a bevel geared three-roll wrist with nonzero oblique angle. The total motion of the wrist is decomposed into three independent component motions, which are easier to analyze. A superposition tabulation is then constructed to derive the relations among the three wrist joint variables and three coaxial actuation variables. The displacement solution for the wrist joint variables is found by using the zero reference position method.