A branch and prune algorithm for the computation of generalized aspects of parallel robots

S. Caro, D. Chablat, A. Goldsztejn*, D. Ishii, C. Jermann

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    23 Citations (Scopus)


    Parallel robots enjoy enhanced mechanical characteristics that have to be contrasted with a more complicated design. In particular, they often have parallel singularities at some poses, and the robots may become uncontrollable, and could even be damaged, in such configurations. The computation of the connected components in the set of nonsingular reachable configurations, called generalized aspects, is therefore a key issue in their design. This paper introduces a new method, based on numerical constraint programming, to compute a certified enclosure of the generalized aspects. Though this method does not allow counting their number rigorously, it constructs inner approximations of the nonsingular workspace that allow commanding parallel robots safely. It also provides a lower-bound on the exact number of generalized aspects. It is moreover the first general method able to handle any parallel robot in theory, though its computational complexity currently restricts its usage to robots with three degrees of freedom. Finally, the constraint programming paradigm it relies on makes it possible to consider various additional constraints (e.g., collision avoidance), making it suitable for practical considerations.

    Original languageEnglish
    Pages (from-to)34-50
    Number of pages17
    JournalArtificial Intelligence
    Issue number1
    Publication statusPublished - 2014


    • Generalized aspects
    • Numerical constraints
    • Parallel robots
    • Singularities

    ASJC Scopus subject areas

    • Artificial Intelligence
    • Language and Linguistics
    • Linguistics and Language


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