International Journal of Control, Automation and Systems

, Volume 11, Issue 1, pp 116–126

Forward kinematic singularity avoiding design of a Schönflies motion generator by asymmetric attachment of subchains

Regular Paper Robotics and Automation

DOI: 10.1007/s12555-012-0005-5

Cite this article as:
Kim, S.M., Yi, BJ. & Kim, W. Int. J. Control Autom. Syst. (2013) 11: 116. doi:10.1007/s12555-012-0005-5


In most of the previous studies on parallel mechanisms (PMs), architectural design mainly relying on symmetric geometry was investigated without in-depth analysis of its performance. This work demonstrates that such a symmetric geometry of multiple subchains sometimes induces a forward kinematic singularity which degrades the overall kinematic performance of PMs within the desired workspace and claims that an asymmetric attachment of those subchains on a moving platform can effectively resolve such a singularity problem. A 4-Degree-of-Freedom (DOF) PM exhibiting Schönflies motions is examined as an example device. First, its mobility analysis and kinematic modeling via screw theory are conducted. Then a singularity analysis based on Grassmann line geometric conditions is carried out, and the forward kinematic singularities of the mechanism are identified and verified by simulations. Based on these analysis and simulations, a forward kinematic singularity-free design is suggested. To show the high potential of the device in practical applications, its output stiffness and dynamic motion capability are examined. Then a prototype is built and its motions capability is verified through experiments.


Forward kinematic singularitykinematic designmobility analysisparallel mechanismSchönflies motionsingularity analysis

Copyright information

© Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Department of Control and Instrumentation EngineeringKorea UniversitySeoulKorea
  2. 2.Department of Electronic Systems EngineeringHanyang UniversityHanyangKorea