Workspace and Manipulability Analysis of a 4-R ̅RR Redundant Planar Parallel Manipulator


  • Amnad Tongtib Department of Energy Management Engineering, Faculty of Industrial Technology, Uttaradit Rajabhat University
  • Chawalit Khanakornsuksan Department of Farm Mechanics, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Kamphaeng Saen
  • Chawalit Khanakornsuksan Department of Farm Mechanics, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Kamphaeng Saen



Parallel Manipulator, Redundant Mechanism, Workspace, Manipulability Index


Planar parallel manipulator has advantages to carry out high speed and accuracy tasks, but singular configurations can occur within a workspace. These singular configurations can be eliminated by adding redundant actuation. This paper presents an analysis of workspace ratio and Manipulability Index (MI) of a 4-RRR redundant planar parallel manipulator, which is created by introducing a redundant branch with active actuator to a 3-"R" ̅RR. Each branch made up as serial chain connects the moving platform to the fixed base by actuator, two rigid links and 2 passive revolute joints. A geometry method based on the forward kinematics would be appropriate to determine the workspace. Then, 4-"R" ̅RR workspace is generated by the intersection of all branched. MI of point in intersection workspace are analyzed. Finally, case study, a comparison of workspace ratio and MI of 3-"R" ̅RR and 4-"R" ̅RR parallel manipulator shown the 4-"R" ̅RR redundant structure can improve the MI to 37 times (for 400 mm and 500 mm of lower and upper link length, respectively) when compared with the 3-"R" ̅"RR" structure while the workspace ratio reduced to 13.15%.


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How to Cite

Tongtib, A. ., Khanakornsuksan, C. ., & Khanakornsuksan, C. . (2022). Workspace and Manipulability Analysis of a 4-R ̅RR Redundant Planar Parallel Manipulator. RMUTL Engineering Journal, 7(1), 33–42.



Research Article