A Gough/Stewart-type platform under a combined scheme of actuation

Abstract

This work reports on the kinematic analyses of a kind of Gough-Stewart platform where the pose of the moving platform is controlled by means of a combination of active revolute and prismatic joints. With this selected scheme of actuation, all the reachable poses of the moving platform stem from the multiple solutions of a fourth-order system of three algebraic equations in three unknowns which is established based on a new formulation of the forward displacement analysis of parallel manipulators. Furthermore, the implementation of three rotary sensors allows to obtain a closed-form solution for the forward displacement analysis. On the other hand, the input/output equations of velocity, acceleration, and jerk, as well as the singularity analysis, of the robot are easily established by resorting to the theory of screws. In order to show the application of the method of kinematic analysis, a case study is included. The numerical example is verified with the aid of commercially available software. © 2013 Springer-Verlag London.