Design of a Dynamically Reconfigurable 3T1R Parallel Kinematic Manipulator

In this paper, the design of a 3T1R (three translations and two rotations) reconfigurable parallel robot using screw theory to define constraints within the limbs is presented. The design is based on the current architecture of a 3T parallel robot and applies screw theory to add two extra rotations through type synthesis of a reconfigurable moving platform with lockable revolute joints. The reconfiguration benefits from keeping the same number of actuators and adding the capability of new motions. The kinematics of the new reconfigurable platform and the constraint Jacobian are calculated. The workspace of the new configuration is computed and compared with the workspace of the original configuration showing an increase of said workspace. Also, the dexterity of the new configuration, based on the local conditioning index, is computed and analysed. Through a simulation of a peg-in-hole motion in Matlab, the way the reconfiguration can be achieved with a reconfigurable parallel robot is finally shown.