Design and analysis of a re-configurable parallel robot

In this paper a re-configurable parallel robot is presented which consists of two base tripods. The first tripod is made of three prismatic joints with the fixed-leg length, called slide tripod. The second tripod is made of three revolute joints, called swing tripod. While the slide tripod is fixed to the moving platform, the branches of the swing tripod are designed to be detachable from the moving platform. By detaching one or two or three branches of the swing tripod separately, this parallel robot can be re-configured from 6 degrees-of-freedom to 5 or 4 or 3 degrees-of-freedom, respectively. In addition, the detached branches can be used to perform collaborative work with the parallel robot. To describe this design, first, design methodology is presented. Then a parametric model is developed to model the constraint equations resulting from re-configuration. Based on this model a unified method is developed to solve the constraint equations. Furthermore, a unified method is presented to solve the inverse kinematics considering varying configurations including 3, 4, 5 and 6 DOFs. Finally, an application case is presented to show that the proposed re-configurable parallel robot can be re-configured to perform tasks that would otherwise require two robots.