Kinematics, workspace and singularity analysis of a multi-mode parallel robot
This work addresses the design and analysis of reconfigurable parallel robots for applications requiring flexible motion modes, but it is incremental as it builds on existing concepts of constraint singularities and lockable joints.
The paper tackles the kinematics, workspace, and singularity analysis of a 3-PRPiR parallel robot with lockable joints, enabling reconfiguration between 3T and 2T1R operation modes, and uses a prototype to illustrate the results.
A family of reconfigurable parallel robots can change motion modes by passing through constraint singularities by locking and releasing some passive joints of the robot. This paper is about the kinematics, the workspace and singularity analysis of a 3-PRPiR parallel robot involving lockable Pi and R (revolute) joints. Here a Pi joint may act as a 1-DOF planar parallelogram if its lock-able P (prismatic) joint is locked or a 2-DOF RR serial chain if its lockable P joint is released. The operation modes of the robot include a 3T operation modes to three 2T1R operation modes with two different directions of the rotation axis of the moving platform. The inverse kinematics and forward kinematics of the robot in each operation modes are dealt with in detail. The workspace analysis of the robot allow us to know the regions of the workspace that the robot can reach in each operation mode. A prototype built at Heriot-Watt University is used to illustrate the results of this work.