Reconfiguration Analysis and Motion Planning of a Novel Reconfigurable Mobile Manipulator Torso

A novel 2-RER reconfigurable parallel mechanism (ReConBot) considered as the flexible torso of the mobile manipulator is proposed. This paper deals with the analysis of reconfiguration, kinematics, and motion planning. The ReConBot is composed of straight bar-shape base and moving platforms and two metamorphic kinematic chains (MKC) consisted of a revolute (R) joint, a planar (E) joint, and an R joint in sequence. Firstly, mobility and reconfiguration analysis discuss the conditions and mutual mode transition rules of 12 possible configuration states. And then, the kinematics model covers all states with Cartesian coordinate and axis/angle representations. What's more, the motion planning following the rules of the mode transition is explained and illustrated together with a case study. Furthermore, the method of handling the transition at singularity position is discussed. Finally, the robotic system and its experiments verify the correctness of the theoretical analysis and the validation of reconfiguration rules.