Autors: Bratovanov, N. G., Sotirov, Z. M., Zamanov, V. B.
Title: Mobility and Accuracy Analysis of a Class of Overconstrained Parallel Mechanisms
Keywords: overconstrained closed-loop mechanisms, parallel manipulators, mobility and accuracy analysis, motion simulations, SolidWorks 3D modeling

Abstract: The paper contributes to the mechanics of a class of overconstrained parallel manipulators. It presents an analytical approach to studying the mobility and accuracy of a special type of parallel manipulator, which has found broad industrial application in semiconductor automation. This is a three-degree-of-freedom closed loop mechanism, which exhibits local mobility in close vicinity of specific (singular) configurations. A distinctive feature of this mechanism when in a specific singular configuration is its ability to “use” the inherent elasticity and backlash of its components in order to perform finite small rotations, instead of using additional kinematic joints. The paper provides a formal description of the motion of the mechanism and its accuracy characteristics by analyzing the equations of constraints imposed on its links. The theoretical results are validated by computer simulations and 3D modeling with SolidWorks.


  1. Bratovanov, N., Sotirov, Z., Zamanov, V., 2017, Modeling and Simulation of Overconstrained Closed-Loop Mechanisms, Proceedings of Technical University of Sofia, Volume 67(2), pp. 81-90
  2. Genov, G., Sotirov, Z., Bonev, E., 1998, Robot Motion Compensation System, U.S., <US6489741B1>
  3. Genov, G., Todorov, D., 1996, Universally Tiltable Z-Axis Drive, U.S., <US5954840>
  4. Gogu, G., 2008, Structural and Kinematic Analysis and Synthesis of Parallel Robots, e-book, Clermont-Ferrand, France, SSIR-Clermont-Ferrand, <>, Дата на последен преглед (Last accessed on): 06.02.2020
  5. Hogben, L., Rosen, K., 2007, Handbook of Linear Algebra, New York, Taylor & Francis Group
  6. Jian, S. D., Zhen, H. and Harvey, L., 2006, Mobility of Overconstrained Parallel Mechanisms, Journal of Mechanical Design, Volume 128(1), pp. 220-229
  7. Wikipedia, 2017, Moore-Penrose pseudoinverse, <–Penrose_pseudoinverse>, Дата на последен преглед (Last accessed on): 10.02.2020
  8. Özgün, S., 2012, Structural and kinematic synthesis of overconstrained mechanisms, Ph.D., <Izmir Institute of Technology>
  9. Sheng, G., Haibo, Q., Yuefa, F., Congzhe, W., 2012, The DOF Degeneration Characteristics of Closed-Loop Overconstrained Mechanisms, Transactions of the Canadian Society for Mechanical Engineering, Volume 36(1), pp. 67-82
  10. Sotirov, Z.M., Parallel-Series Manipulators in Semiconductor Automation, Semiconductor European, July 2002


Mechanics of Machines, issue 2, pp. 26-32, 2018, Bulgaria, ISSN 0861-9727

Full text of the publication

Вид: публикация в национален форум, публикация в реферирано издание