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Brethe J.-F.,CNRS Research Group of Electrotechnics and Automatics of Le Havre
Journal of Mechanisms and Robotics | Year: 2011

In this paper, the author proposes a new method to design SCARA robots for higher repeatability. First, the author outlines various procedures used in optimal robot design and then points out among the various performance indices those related to repeatability. The author adds some new criteria issued from the stochastic ellipsoid theory. Another innovative part of the paper is to take into account a task-oriented strategy during the design stage, meaning the possibility of adapting task orientation and location in the robot workspace. These concepts are applied to SCARA optimal design. The method described here consists of considering simultaneously robot geometry and joint repeatability, keeping both the reach and the total cost of the sensors constant. It results in an optimization problem with adimensional ratios, which then allows easy comparisons with existing SCARA. The results are surprising and give some clues to answer the underlying question: Are industrial SCARA designed for high repeatability? © 2011 American Society of Mechanical Engineers. Source

Zandi M.,CNRS Research Group in Electrotechnics and Electronics of Nancy | Payman A.,CNRS Research Group of Electrotechnics and Automatics of Le Havre | Martin J.-P.,CNRS Research Group in Electrotechnics and Electronics of Nancy | Pierfederici S.,CNRS Research Group in Electrotechnics and Electronics of Nancy | And 2 more authors.
IEEE Transactions on Vehicular Technology | Year: 2011

This paper presents an energy management method in an electrical hybrid power source (EHPS) for electric vehicular applications. The method is based on the flatness control technique (FCT) and fuzzy logic control (FLC). This EHPS is composed of a fuel cell system as the main source and two energy storage sources (ESSs)a bank of supercapacitors (SCs) and a bank of batteries (BATs)as the auxiliary source. With this hybridization, the volume and mass of the EHPS can be reduced, because the high energy density of BAT and high power density of SC are utilized. In the proposed novel control strategy, the FCT is used to manage the energy between the main and the auxiliary sources, and the FLC is employed to share the power flow in the ESS between the SC and the BAT. The power sharing depends on the load power and the state of charge of the SC and the BAT. EHPS is controlled by the regulation of the stored electrostatic energy in the dc buses. The main property of this strategy is that the energy management in the power source is carried out with a single general control algorithm in different operating modes, consequently avoiding any algorithm commutation. An EHPS test bench has been assembled and equipped with a real-time system controller based on a dSPACE. The experimental results validate the efficiency of the proposed control strategy. © 2006 IEEE. Source

Brethe J.-F.,CNRS Research Group of Electrotechnics and Automatics of Le Havre
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2010

The paper deals with the question of robot precision and how to characterise repeatability. Hence ISO and ANSI repeatability indexes advantages and drawbacks are analysed. A new intrinsic repeatability index is proposed that can estimate the robot endpoint position variability satisfying the non-bias and convergence conditions. Computation of this index is performed using simulated straight and drifting trajectories. Influence of load on repeatability is studied using an experimental determination of an angular covariance matrix. Therefrom intrinsic repeatability can be computed in every workspace location using only this covariance matrix and the stochastic ellipsoid theory. ©2010 IEEE. Source

Brethe J.-F.,CNRS Research Group of Electrotechnics and Automatics of Le Havre
IEEE International Conference on Intelligent Robots and Systems | Year: 2011

The paper aims at modeling and quantifying robot precision when it is possible to obtain information from external sensors in the operating area. The author proves that in this situation, neither the pose repeatability, nor the pose accuracy are adequate to calculate the maximum position error. A new paradigm is then proposed: granulous space modeling which combines spatial resolution and actuators' repeatability. This stochastic modeling is first detailed in unidimensional space then in the case of bidimensional space. The methodology to compute the maximal position error is given and compared with other approaches. © 2011 IEEE. Source

Camara M.B.,CNRS Research Group of Electrotechnics and Automatics of Le Havre | Gualous H.,University of Franche Comte | Gustin F.,University of Technology of Belfort - Montbeliard | Berthon A.,University of Technology of Belfort - Montbeliard | Dakyo B.,CNRS Research Group of Electrotechnics and Automatics of Le Havre
IEEE Transactions on Industrial Electronics | Year: 2010

This paper presents supercapacitor (SCAP) and battery modeling with an original energy management strategy in a hybrid storage technology. The studied dc power supply is composed of SCAPs and batteries. SCAPs are dimensioned for peak power requirement, and batteries provide the power in steady state. A bidirectional dc/dc converter is used between SCAPs and the dc bus. Batteries are directly connected to the dc bus. The originality of this study is focused on SCAP behavior modeling and energy management strategy. The proposed strategy is based on a polynomial (RST) controller. For reasons of cost and existing components (not optimized) such as batteries and semiconductors, the experimental test benches are designed in reduced scale. The characterized packs of SCAPs include two modules of ten cells in series for each one and present a maximum voltage of 27 V. The proposed strategy is implemented on a PIC18F4431 microcontroller for two dc/dc converter topology controls. Experimental and simulation results obtained from the polynomial control strategy are presented, analyzed, and compared with that of classical proportionalintegral control. © 2009 IEEE. Source

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