Brahim Ahmed Chekh Oumar
@tekniker.es
Scopus Publications
- Generalising the Machine Tool Integrated Inverse Multilateration Method for the Ambient Thermal Error Analysis of Large Machine Tools in Industrial Environments
Fernando Egaña, Unai Mutilba, José A. Yagüe-Fabra, B. Ahmed Chekh, Susana Lopez
Applied Sciences Switzerland, 2025
This study expands on prior research by generalising the machine tool integrated inverse multilateration methodology to evaluate ambient thermal effects on medium- and large-sized machine tools in industrial environments. This method integrates an absolute distance measurement device into the machine tool spindle, enabling an automated and robust multilateration scheme without requiring controlled environments, expensive thermal instruments, or specialised artifacts. Tests were conducted using a LEICA AT960™ laser tracker and wide-angle retro-reflectors (both from Hexagon Manufacturing Intelligence, Stockholm, Sweden) across two machine architectures, THERA™ (gantry type) and ZERO™ (bed type), building on earlier work with the ARION G™ (bridge type), all of them MTs manufactured by Zayer (Vitoria, Spain). Sequential experiments in varying ambient conditions demonstrated the reliability of the machine tool integrated inverse multilateration approach over extended periods, showing strong correlations between the measured errors and temperature variations. The results were validated using a first-order mathematical model and finite element method simulations, confirming thermal error evolution as a function of ambient temperature changes. This method’s adaptability to diverse machine architectures and industrial conditions highlights its potential for characterising and mitigating thermal errors in large machine tools. This work underscores the method’s effectiveness and utility for advancing thermal error analysis in practical manufacturing settings. - A Shared Metrological Framework for Trustworthy Virtual Experiments and Digital Twins
Giacomo Maculotti, Manuel Marschall, Gertjan Kok, Brahim Ahmed Chekh, Marcel van Dijk, Jon Flores, Gianfranco Genta, Pablo Puerto, Maurizio Galetto, Sonja Schmelter
Metrology, 2024
Virtual experiments (VEs) and digital twins (DTs), pivotal for realizing European strategic policies on sustainability and digitalization within Industry 4.0 and the European Green Deal, simulate physical systems and characteristics in a virtual environment, with DTs incorporating dynamic inputs from and outputs to the real-world counterpart. To ensure confidence in their use and outcomes, traceability and methods to evaluate measurement uncertainty are needed, topics that are hardly covered by the literature so far. This paper provides a harmonized definition of VEs and DTs and introduces a framework for evaluating measurement uncertainty. Furthermore, it discusses how to propagate the uncertainty of the contributions coming from the different parts of the DT. For the core part of the DT, the framework derived for VEs can be used. For the physical-to-virtual (P2V) connection and the virtual-to-physical (V2P) connection, additional sources of uncertainty need to be considered. This paper provides a metrological framework for taking all these uncertainty contributions into account while describing a framework to establish traceability for DTs. Two case studies are presented to demonstrate the proposed methodology considering industrially relevant measuring instruments and devices, namely, a coordinate measuring machine (CMM) and a collaborative robot arm (cobot). - A method for the 3D identification of the center of gravity of an aircraft
Oscar Gonzalo, Jose Maria Seara, Brahim Ahmed Chekh, Iñigo Berreteaga, Maurizio Marrocu, Enrico Rotondi
Measurement Journal of the International Measurement Confederation, 2023 - Compact system for fast on-line geometry characterization of facets for solar concentrators
B. Ahmed Chekh, Jesús Fernández-Reche, Loreto Valenzuela, Cristobal Villasante, Gorka Kortaberria, Diego Pulido-Iparraguirre
Aip Conference Proceedings, 2022
This paper presents an alternative in process quality control inspection system for facets (mirrors) of an optical concentrator. The knowledge of the geometrical shape of these optical surfaces is crucial to ensure a suitable performance of the solar collector. Currently close-range photogrammetry or deflectometry techniques are available to measure the geometry of solar reflectors, where the measurement preparation and processing times are important limitations for high ratio production quality control. The alternative inspection solution depicted in this paper is the application of an inline control system of solar reflectors based on the autocollimation principle which has been conceived in Tekniker. This system has been adapted to measure linear Fresnel reflectors (LFR) in this project. In the work carried out a measurement of a set of linear Fresnel reflector units facets have been performed to validate the implementation of the autocollimators cell in the Plataforma Solar de Almeria (CIEMAT-PSA). Differences in the mrad order between the current photogrammetric approach and the proposed autocollimator based cell solution are obtained, validating the suitability and feasibility of this system for the facet inspection with high production rates. - ACVISION: A six-degree-of-freedom measuring system combining autocollimation and photogrammetric principles
Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology Euspen 2021, 2021 - Extrinsic calibration and kinematic modelling of a laser line triangulation sensor integrated in an intelligent fixture with 3 degrees of freedom
B.A. Chekh, G. Kortaberria, O. Gonzalo
Precision Engineering, 2019
