Abstract
In this paper, we study self-motions of non-architecturally singular parallel manipulators of Stewart Gough type, where the planar platform and the planar base are related by a projectivity. By using mainly geometric arguments, we show that these manipulators have either so-called elliptic self-motions or pure translational self-motions. In the latter case, the projectivity has to be an affinity a+Ax, where the singular values s 1 and s 2 of the 2×2 transformation matrix A with 0<s 1≤s 2 fulfill the condition s 1≤1≤s 2.
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Notes
- 1.
If κ is singular, one set of anchor points would collapse into a line or a point, which yields trivial cases of architecturally singular manipulators.
- 2.
Neither all platform anchor points nor all base anchor points collapse into one point.
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Acknowledgements
This research is supported by Grant No. I 408-N13 of the Austrian Science Fund FWF within the project “Flexible polyhedra and frameworks in different spaces”, an international cooperation between FWF and RFBR, the Russian Foundation for Basic Research.
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Nawratil, G. (2012). Self-Motions of Planar Projective Stewart Gough Platforms. In: Lenarcic, J., Husty, M. (eds) Latest Advances in Robot Kinematics. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-4620-6_4
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DOI: https://doi.org/10.1007/978-94-007-4620-6_4
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