Abstract: 3-UPU parallel mechanisms, whose axes of hooke joint on base plate and moving plate fit different geometric constraints, can have translational or orientational output. A configuration-switch mechanism for 3-UPU parallel mechanism is designed based on the theory of metamorphic that change the orientations of kinematic pairs can lead to configuration transformation. This mechanism consists of two identical kinematic chains fixed on base plate and moving plate respectively. In order to change output and design a novel parallel metamorphic mechanism, the joint of two identical kinematic chains transforms to make axes of hooke joints change between parallel and jointed. A proper configuration-switch position affects the working performance of consequent configuration, since metamorphic mechanisms have multigroup couple relationship. Screw theory is adopted to calculate the DOF of this parallel metamorphic mechanism in different configuration respectively. Taking the mechanisms’ workspace for example, the effect of the configuration-switch position on working performance of mechanisms in different configuration is analyzed.

Key words: configuration switch, metamorphic mechanism, parallel mechanism, workspace