6 papers
Compactification of the group of rigid motions and applications to robotics
Nestor Djintelbe, Michel Coste
We introduce a compactification of the group of rigid motions in 3-space derived from the Study model for this group. We use this compactifi-cation in robot kinematics, by consider…
Rationality Of the Locus Of Singularities Of the General Gough-Stewart Platform
Michel Coste, Seydou Moussa
We prove that the set of singular configurations of a general Gough Stewart platform has a rational parametrization. We introduce a reciprocal twist mapping which, for a general or…
Dynamical method in algebra: Effective Nullstellensätze
Michel Coste, Henri Lombardi, Marie-Françoise Roy
We give a general method for producing various effective Null and Positivstellensätze, and getting new Positivstellensätze in algebraically closed valued fields and ordered groups.…
Hidden cusps
Michel Coste, Philippe Wenger, Damien Chablat
This paper investigates a situation pointed out in a recent paper, in which a non-singular change of assembly mode of a planar 2-RPR-PR parallel manipulator was realized by encircl…
Singular surfaces and cusps in symmetric planar 3-RPR manipulators
Michel Coste, Philippe Wenger, Damien Chablat
We study in this paper a class of 3-RPR manipulators for which the direct kinematic problem (DKP) is split into a cubic problem followed by a quadratic one. These manipulators are…
Geodesic diameter of sets defined by few quadratic equations and inequalities
Michel Coste, Seydou Moussa
We prove a bound for the geodesic diameter of a subset of the unit ball in described by a fixed number of quadratic equations and inequalities, which is polynomial i…