Characterizing and approximating eigenvalue sets of symmetric interval matrices

We consider the eigenvalue problem for the case where the input matrix is symmetric and its entries perturb in some given intervals. We present a characterization of some of the exact boundary points, which allows us to introduce an inner approximation algorithm, that in many case estimates exact bounds. To our knowledge, this is the first algorithm that is able to guaran- tee exactness. We illustrate our approach by several examples and numerical experiments

Robotique : des aides abordables pour nos aînés

National audienceLe maintien à domicile aussi longtemps que possible des personnes vieillissantes s'avère être la solution la plus rationnelle, tant en termes de confort que de coûts sociaux. D'où l'intérêt de dispositifs robotisés pour les assister au quotidien

Self Calibration of Gough Platform using leg mobility constraints

International audienceA new algorithm for the calibration of a gough platform is presented. It enables auto-calibration as it only uses internal measurements : the leg lengths In order to obtain the necessary information to do so, without adding additional sensors. we introduce some constraints on two legs of the robot. First, the method is described. Second, it is validated by simulation

Mobility constraints on the legs of a parallel robot to improve the kinematic calibration.

International audienceDue to errors such as manufacturing or assembly defects, it is well known that the geometry of robotics manipulators do es not exactly match the design goals. A direct drawback lies in a reduced accuracy of the manipulator which turns out to b e a problem since rob to control requires accurate kinematic models. One way to tackle this problem consists in improving the knowledge of the kinematic model using kinematic calibrations. This is the problem we address in the contribution for parallel robot

An Algorithm for the Real Interval Eigenvalue Problem

In this paper we present an algorithm for approximating the range of the real eigenvalues of interval matrices. Such matrices could be used to model real-life problems, where data sets suffer from bounded variations such as uncertainties (e.g. tolerances on parameters, measurement errors), or to study problems for given states. The algorithm that we propose is a subdivision algorithm that exploits so- phisticated techniques from interval analysis. The quality of the computed approximation, as well as the running time of the algorithm depend on a given input accuracy. We also present an efficient C++ implementation and illustrate its efficiency on various data sets. In most of the cases we manage to compute efficiently the exact boundary points (limited by floating point representation)

A filtering method for the interval eigenvalue problem

We consider the general problem of computing intervals that contain the real eigenvalues of interval matrices. Given an outer estimation of the real eigenvalue set of an interval matrix, we propose a filtering method that improves the estimation. Even though our method is based on an sufficient regularity condition, it is very efficient in practice, and our experimental results suggest that, in general, improves significantly the input estimation. The proposed method works for general, as well as for symmetric matrices

Self Calibration of Gough Platform using leg mobility constraints

International audienceA new algorithm for the calibration of a gough platform is presented. It enables auto-calibration as it only uses internal measurements : the leg lengths In order to obtain the necessary information to do so, without adding additional sensors. we introduce some constraints on two legs of the robot. First, the method is described. Second, it is validated by simulation

Interval Methods for Model Qualification: Methodology and Advanced Application

It is often too complex to use, and sometimes impossible to obtain, an actual model in simulation or command field . To handle a system in practice, a simplification of the real model is then necessary. This simplification goes through some hypotheses made on the system or the modeling approach. In this paper, we deal with all models that can be expressed by real-valued variables involved in analytical relations and depending on parameters. We propose a method that qualifies the simplification validity by verifying a quality threshold on the hypothesis relevance. This method, based on interval analysis, can check the acceptance of the hypothesis in a full range of the whole model space, and can give bounds to the quality threshold and to the model parameters.% to keep the simplified model acceptable. Our approach is experimentally validated on a robotic application.Ce document présente une méthode base sur l'analyse par intervalle servant a la vérification d'une hypothèse utilisée dans le cadre d'une simplification de modèle. Une application en robotique est présentée

Leaning against the wind: Effects of macroprudential policy on sectoral

Abstract. Use of macroprudential policies in recent years has gained relevance in different economies. As a result of the financial crisis in 2008, this instrument was useful in emerging economies to reduce the effects of the adverse international context. The relationship between financial intermediation and the real sector is positive, in response to shocks in productive credit the sectoral growth is 0.15pp in 2016. Likewise, the modification of the reserve requirement rate can provide or with draw liquidity from the financial system, in the first case, the objective is to increase portfolio placement, which affects the development of productive sectors. Therefore, there is a need to evaluate the effect of changes in the reserve requirement rateon sectoral growth in Bolivia, which was offset by the financial cycle because episodes of Credit Crunch affect the real sector (the economic cycle is amplified to the downside). The methodologies used are the Fixed Effects (FE), Random Effects (RA) and Panel Autoregresive Vectors (Panel-VAR) and recursive versions of them. The positive effects of the macroprudential policy and changes in the position that this instrument had over time, depending on the financial cycle, Leaning Against the Wind. Reserve requirement ratedecreasesof the national currency has positive impact on sectoral growth and tests with recursive versions shows positive effects and increase of credit towards the sectoral activity.Keywords. Reserve requirements, Interest rate, Fixed effects (EF), Random effects (RE), Panel VAR, Recursive estimation, Leaning against the wind.JEL. C50, E51, E52

Simulation Study of the Upper-limb Wrench Feasible Set with Glenohumeral Joint Constraints

The aim of this work is to improve musculoskeletal-based models of the upper-limb Wrench Feasible Set i.e. the set of achievable maximal wrenches at the hand for applications in collaborative robotics and computer aided ergonomics. In particular, a recent method performing wrench capacity evaluation called the Iterative Convex Hull Method is upgraded in order to integrate non dislocation and compression limitation constraints at the glenohumeral joint not taken into account in the available models. Their effects on the amplitude of the force capacities at the hand, glenohumeral joint reaction forces and upper-limb muscles coordination in comparison to the original iterative convex hull method are investigated in silico. The results highlight the glenohumeral potential dislocation for the majority of elements of the wrench feasible set with the original Iterative Convex Hull method and the fact that the modifications satisfy correctly stability constraints at the glenohumeral joint. Also, the induced muscles coordination pattern favors the action of stabilizing muscles, in particular the rotator-cuff muscles, and lowers that of known potential destabilizing ones according to the literature.Comment: 30 pages (double spacing), 10 figures, 2 table