MERLET , Jean-Pierre

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Although workspace is essential for the design and control of cable-driven parallel robots (CDPR) very few works have been devoted to this topic when sagging cables are considered , most probably because of the complexity of the cable model. In this paper we consider suspended CDPR with sagging cables that can support only a limited tension. We...

International audience

Finding the workspace of cable driven parallel robots (CDPR) with sagging cables (i.e. elastic and deformable cables) is a problem that has never been fully addressed in the literature as this is a complex issue: the inverse kinematics may have multiple solutions and the equations that describe the problem are non-linear and non algebraic. We...

A classical planar cable model has been presented in the Irvine textbook and is being used, for example, for the modeling of cable-driven parallel robot. It provides 2 equations involving parameters of the cable material, namely its Young modulus and its linear density, assumed here to be known, and 5 physical parameters namely the coordinates...

Positioning accuracy of cable-driven parallel robots is influenced by many factors such as geometry, actuator sensor accuracy and disturbances in the applied wrench. Another uncertainty source is the elasticity of the cables. While the influence of many factors may be decreased by calibration and/or sensor fusion, elasticity parameters are...

Nous décrivons l'expérience de l'équipe Hephaistos de l'INRIA, travaillant en robotique d'assistance aux personnes fragiles, dans le domaine de la conception d'objets, de l'expérimentation avec ces objets ainsi que dans l'analyse des données issues de l'expérimentation. Les objets conçus le sont pour deux champs très différents : des systèmes...

Cable-driven parallel robot (CDPR) are parallel robots that use coilable cables as legs. We are interested here in suspended CDPR for which there is no cable that exert a downward force on the platform. If we assume that the cables are mass-less and not elastic it has been shown that at a given pose whatever is the number m > 6 of cables there...

This paper addresses the problem of the forward kinematics of cable-driven parallel robots (CDPR) having elastic or non elastic cables under the assumption that the cables are submitted to small changes in their lengths compared to an initial situation at which the pose is known, a situation that is typical of a real-time forward kinematics...

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Avec l'apparition de la robotique de service, les robots évoluent de plus en plus au contact des humains. Quelles questions cela soulève-t-il ?

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International audience

This paper addresses the simulation of the state of a discrete-time controlled cable-driven parallel robot (CDPR) with nondeformable or elastic cables over a given trajectory. Being given a CDPR, an arbitrary model for the coiling system and for the control strategy, we exhibit a simulation algorithm that allows one to determine, in a...

These databases provide learning and verification sets that may used by AI to solve the direct kinematics of a cable-driven parallel robot with 8 cables. The input of this problem is the lengths of th 8 cables and the output should be all platform poses that are compatible with the cable lengths. The cable model that is used is the full model...

International audience

Les robots seront-ils essentiels à la sauvegarde de l'autonomie des personnes fragiles ? Pour ce faire, un engin humanoïde multitâche serait moins efficace qu'une flottille d'appareils spécifiques travaillant en équipe...

Cable model has a strong influence on the complexity of the kinematic analysis of cable-driven parallel robots (CDPR). The most complete elasto-static model relies on Irvine equation that takes into account both the elasticity and the deformation of the cable due to its own mass and has been shown to be very realistic. This model is complex,...

Solving the kinematics of CDPR is complex as soon as cable sagging is taken into account. We are considering here CDPRs having 2 cables whose extremities are attached at the same point on the platform (i.e. CDPRs allowing only translational motion). Regarding the cables we assume that they are nonelastic but have a mass so that they will...

Direct kinematics (DK) of cable-driven parallel robots (CDPR) based only on cable lengths measurements is a complex issue even with ideal cables and consequently even harder for more realistic cable models such as sagging cable. A natural way to simplify the DK solving is to add sensors. We consider here sensors that give a partial or complete...

Determining what will be the maximal cable tensions of a cabledriven parallel robot (CDPR) when it moves over a given workspace is an important step in the design phase as it will allow to choose the cable diameter and to provide a requested information for tuning the CDPR actuation. In this paper we consider a suspended N-1 CDPR with n cables...

Direct kinematics (DK) is one of the most challenging problem for cable-driven parallel robot (CDPR) with sagging cables. Solving the DK in real-time is not an issue provided that a guess of the solution is available. But difficulties arise when all DK solutions have to be determined (e.g. in the design phase of the CDPR). Continuation and...

Cable lengths is an important input for determining the state of a CDPR. Using drum with helical guide may be appropriate for small or medium-sized CDPR but are problematic for large one. Another issue is the initialization of the cable length as measurements based on drum rotation are incremental. We propose to address automatic initialization...

We consider in this paper cable driven parallel robot (CDPR) with m catenary cables that present a significant deformation due to their elasticity and own mass and we address the kinematics of such a robot under the assumption of static state. We show that the inverse kinematics (IK) requires to solve a square system of equations if the robot...