Calibration of a fully-constrained parallel cable-driven robot

An identi cation of the model parameters for a parallel cable-driven robot is performed by using both a calibration and a self-calibration approach. The manipulator studied is based on a parallel architecture having 8 cables to control the 6 degrees of freedom of its mobile platform so that the mobile platform is fully constrained by the cables. Under some hypotheses on cable properties, the interest of redundancy in actuation is exploited to self-calibrate by using proprioceptive sensors. This approach is compared to the di culties to implement a calibration process. Additionally, advanced tools and algorithmic improvements are presented to perform the parameter identi cation. A complete experimentation validates the robot accuracy improvement after calibration or self-calibration. We show that the basic hypotheses on cable properties are veri ed. Moreover, the investment in terms of time and cost to obtain the external measurements for calibration process does not bring better results and does not balance the simplicity and e ciency of the self calibration process. Key-words: Calibration, Cable-driven Robot, kinematics ∗ Inria † Inria ‡ Lirmm § Tecnalia ha l-0 06 68 92 1, v er si on 1 10 F eb 2 01 2 Etalonnage d'un robot parallèle à câbles sur-contraint rapport de recherche Inria Résumé : Ce document présente les résultats d'un étalonnage et d'un autoétalonnage d'un robot parallèle à câbles. De plus, certaines méthodes d'identi cation sont comparées et une nouvelle approche dite globale est décrite. Mots-clés : Etalonnage, Robot à câbles, Cinématique ha l-0 06 68 92 1, v er si on 1 10 F eb 2 01 2 Calibration of a fully-constrained parallel cable-driven robot 3