Analysis and Design of a Reconfigurable 3-DoF Parallel Manipulator for Multimodal Tasks

This paper presents the design of a reconfigurable 3-DoF parallel kinematics manipulator. The main feature of the device is the ability to change the mobility of its moving platform from pure translation to pure rotation. The manipulator kinematics is conceived so that, when a particular configuration of the manipulator is reached, the transition between the two working modes is possible by changing the configuration of a metamorphic universal joint, which is used to connect the legs of the manipulator with the moving platform. The mechanical design of the joint, which is in fact a lockable spherical joint, is illustrated. With the joint integrated into the robot architecture, an instantaneous overconstrained kinematics is exploited to manage the phase of reconfiguration of the whole mechatronic device. A kineto-static analysis provides information about the influence of geometric parameters on its functional design. The manipulator shows simple kinematics and statics models, as well as good kinematic and static performances. Eventually, the versatility of the manipulator is shown by proposing some advanced manufacturing applications in which it could find use.