Kinematic analysis of a Stewart platform manipulator

Abstract

The Stewart platform manipulator is a fully parallel kinematic linkage system that has major mechanical differences from typical serial link robots. Its closed kinematic chain and parallel linkage structure give it greatly rigidity and a high force-to-weight ratio. However, due to the lack of efficient algorithms for solving the kinematic equations, its potential application as a robotic manipulator is difficult to realize. A simplified algorithm for solving the forward kinematics of a six-link, six-degrees-of-freedom Stewart platform is proposed. The algorithm involves solving only three nonlinear simultaneous equations. Explicit expressions for some special configurations that can directly give the geometric limitations to motion (such as the highest position, lowest position, most titled position, most twisted position, etc.) in terms of the geometric dimensions of the platforms and the legs are derived. This information is being used to direct the design of an actual Stewart platform. >