Planning singularity-free force-feasible paths on the Stewart platform

Conference Article


International Symposium on Advances in Robot Kinematics (ARK)





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The study of the singularity set is of utmost importance to understand the local and global properties of a manipulator. After reviewing the mathemat- ical conditions that characterize this set, and the physical consequences of traversing each singularity type, this paper shows that its defining equations can be formulated in an amenable manner on planar manipulators, allowing to devise a conceptually-simple technique for isolating the set exhaustively, even in higher-dimensional cases. As a result, the method obtains a collection of small boxes bounding the location of all points of the set, which can be computed at any required precision in principle. Such boxes can be projected to the input or output coordinate spaces of the manipulator, obtaining informative diagrams, or portraits, on the global motion capabilities of the underlying mechanism. Examples are included that show the application of the method to simple manipulators, and to complex mechanisms that would be difficult to analyze using common-practice procedures.


robot kinematics.

Author keywords

singularity-free path planning, higher-dimensional continuation, singularity avoidance, Stewart platform

Scientific reference

O. Bohigas, M. Manubens and L. Ros. Planning singularity-free force-feasible paths on the Stewart platform, 13th International Symposium on Advances in Robot Kinematics, 2012, Innsbruck, in Latest Advances in Robot Kinematics, pp. 245-252, 2012, Springer.