Apresentado no XXII World Congress of the International Measurement Confederation (IMEKO 2018.The dimensional inspection is currently consolidated as an important tool in the
improvement of manufacturing processes. The demands of quality and the requirement of parts
with complex speci cations propose new challenges, such as the incorporation of integration
and interoperability concepts in measurement operations. An important issue still unresolved
in the inspection process is the dynamic management of information that requires solutions that
are at the technological forefront and contextualized within the requirements of Industry 4.0.
In this perspective, the implementation of a closed-loop inspection supports the measurement
requirements for di erent manufacturing processes and enables the application for di erent
purposes. The feedback strategy proposed in this article proposes an alternative as a solution
to integrate the inspection results of a part within a digital manufacturing chain based on
STEP-NC (STandard for the Exchange of Product model data - Numerical Control). The
mechanisms for acquisition, processing, and analysis of information, and the control architecture
that complement the feedback strategy is exposed

Riaño, Cristian I.

Álvares, Alberto José

Repositório Institucional da Universidade de Brasília

Journal of Physics: Conference SeriesPAPER • OPEN ACCESSFeedback strategy for closed-loop inspection based on STEP-NCTo cite this article: Cristhian I. Riaño and Alberto J. Álvares 2018 J. Phys.: Conf. Ser. 1065 082014 View the article online for updates and enhancements.This content was downloaded from IP address 164.41.45.205 on 25/02/2019 at 13:08Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdXXII World Congress of the International Measurement Confederation (IMEKO 2018)IOP Conf. Series: Journal of Physics: Conf. Series 1065 (2018) 082014IOP Publishingdoi:10.1088/1742-6596/1065/8/0820141Feedback strategy for closed-loop inspection based onSTEP-NCCristhian I. Rian˜o1, Alberto J. A´lvares11Department of Mechanical Engineering, Bras´ılia University - Campus Universita´rio DarcyRibeiro, Bras´ılia - CEP 70910-900, BrazilE-mail: cristhian.riano@unipamplona.edu.co, alvares@AlvaresTech.comAbstract. The dimensional inspection is currently consolidated as an important tool in theimprovement of manufacturing processes. The demands of quality and the requirement of partswith complex specifications propose new challenges, such as the incorporation of integrationand interoperability concepts in measurement operations. An important issue still unresolvedin the inspection process is the dynamic management of information that requires solutions thatare at the technological forefront and contextualized within the requirements of Industry 4.0.In this perspective, the implementation of a closed-loop inspection supports the measurementrequirements for different manufacturing processes and enables the application for differentpurposes. The feedback strategy proposed in this article proposes an alternative as a solutionto integrate the inspection results of a part within a digital manufacturing chain based onSTEP-NC (STandard for the Exchange of Product model data - Numerical Control). Themechanisms for acquisition, processing, and analysis of information, and the control architecturethat complement the feedback strategy is exposed.1. IntroductionThe concept of smart manufacturing, integrated and interoperability is strongly related to theindustry 4.0 approach [1]. Different cutting-edge technologies converge in this line to use theinformation to optimize processes and maximize efficiency. Constant advances in measurementhave allowed technological developments in both equipment and data processing and analysistechniques, but there are still barriers that prevent fully integrating digital technologies intothe inspection process. One of these barriers is the exchange of information between systemsinvolved in the manufacture of a part [2].The importance of the information obtained in an inspection process is that the data canbe used in other functions besides the already conventional quality control of a part. The dataacquired in the measurement provide both uncertainty and deviation values, as well as relevantinformation on the manufacturing process and manufacturing conditions[3, 4]. Previously, themeasurement process was limited to taking measurements within a controlled environment tocalculate error values, but the demands of efficient processes made measurement an indispensabletool to control and monitor in manufacturing the evolution of a product[5, 6].To exchange information, it is necessary to use a neutral data model, with open architectureand homogenized syntax. This need to transfer information between manufacturing systemsled to the emergence and evolution of standards such as IGES (Initial Graphics ExchangeSpecification), PDES (Product Data Exchange Specification), STEP (Standard for the ExchangeXXII World Congress of the International Measurement Confederation (IMEKO 2018)IOP Conf. Series: Journal of Physics: Conf. Series 1065 (2018) 082014IOP Publishingdoi:10.1088/1742-6596/1065/8/0820142of Product Model Data), among others. The problem of integrating GD&T specifications,execute the measurement, exchanging inspection data, analyzing results and making decisionsis still far from automatic and much of the problem lies in the data structures used to transferthe information.Within this context, a strategy for feedback of inspection results in a close-loop inspectionbased on AP242, AP238 and AP219 protocols of ISO 10303 is presented in this article. Themodel allows a bidirectional flow of information between the processes involved in the processlife cycle of a part.2. CAD data requirements for inspectionTo perform the inspection it is necessary to obtain information from the model product inaddition to the project requirements. In the proposed application scenario the part design isdeveloped based on features. Feature-based part modeling technology is the primary componentin integrating the processes associated with the product life cycle of a part. The STEP standardmainly uses this technology to provide a neutral, interoperable format for the exchange ofproduct information. In building the product model based on the STEP standard it is necessaryto use the unit of functionality (UoF) provided by the application protocols to define the featuresand their properties.There are different tools to aid in the process of creating CAD models, but it is vitallyimportant to develop a measurement plan. The measurement plans contain all the necessaryinformation to control the CMM (Coordinate-measuring machine), in the execution andevaluation of the measurement. The inspection plan creates a procedure to define both theexecution program and a method of post-processing of data. The plan produces a set ofmeasurement points and a list of features along a path to be inspected. The task of greaterrelevance in the plan is the extraction of information that is hampered by the absence of astandard that harmonizes the definitions included in the DMIS, I ++ DME, AP219, ISO 14649,Part 16, DML, QMD among other standards used in the measurement.The Figure 1 shows the feedback scheme based on the STEP standard. The manufacturingand measurement requirements are extracted from a STEP AP242 PMI file to generate aSTEP AP238 file with manufacturing operations. Measurements are made by comparing themathematical definition of the model with the definition that can be computed by measuringpoints on the model.3. Closed-loop inspectionThe measurement system acquires data of the geometry of the piece manufactured in severalpoints located in different dimensional planes, with these values the control system reconstructsthe surface, analyzes and processes the results to quantify the error, identify the causesand generate the compensation. The expert system in charge of processing a large part ofthe information bases its operations on structured knowledge within a set of rules aimed atmaximizing the efficiency of the process. The compensation in the process is generated directlyin the program sent to the control system of the machine tool, which contains the executionroutines to machine a new part. Inspection is repeated after machining, this reduces the errorin each closed-loop system interaction.The control strategy within the closed-loop inspection seeks to compensate the input datato the control system of the CNC with the results of a comparison between the design nominaland the inspected part to meet the quality requirements of the project. The Figure 2 presentsthe control scheme for the integration model.The close-loop control scheme shown in the Figure 2 contains as input the nominal informationof the part where the requirements for quality control are defined. The compensation systemis in charge of generating the orders sent to the CNC controller of the machine tool, adjustingXXII World Congress of the International Measurement Confederation (IMEKO 2018)IOP Conf. Series: Journal of Physics: Conf. Series 1065 (2018) 082014IOP Publishingdoi:10.1088/1742-6596/1065/8/0820143ROUND_HOLEWORKPIECETHROUGH_STEPSLOT_PARTIAL_ROUNDCLOSED_SLOTTHROUGH_SLOTMCS_MILLMachining workingstepsSENSORSPROGRAM_HEADERPART_ALIGNMENTMCS_TO_PCSFEATURESOUTPUTSCMM_PROGRAMInspection workingstepsPROGRAM_HEADER_STATEMENTSPM600M_A0_B0INSPECTION_PATHSCONSTRUCTED_FEATURESTOLERANCESSetup sectionHeader sectionInspection ResultData analysis systemClosed SlotChamfer faceThrough slotCircular Through HoleCylindrical FaceThrough step LengthWidth Height Figure 1. Tolerance model for dimensional and geometric inspection.the code of the nominal part with the necessary changes to satisfy the requirements. The CNCcontrol system of the machine tool executes the numerical commands for machining the part.The inspection system, in charge of acquiring data of the manufactured part, plans, executes andanalyzes the measurement results. On the inspection system is included the feedback strategyto exchange the data within an adherent data model with the ISO 10303.In the manufacturing of part, different disturbances are present, for which errors of differentnature (static, dynamic and progressive) are adhered to the process. The proposed inspectionstrategy aims to identify, monitor and control the errors that a part acquires during themanufacturing process in order to satisfy the expected GD&T requirements. The identificationof sources of error uses so many inspection results as data of the manufacturing conditionsobtained by monitoring the process. The compensation of the geometric error is based on thedetermination of the uncertainty of global form, product of a comparison of the nominal modelwith the real model and make the corrections on the data structure sent to the CNC controllerof the machine tool.4. Compensation strategyThe error compensation strategy uses the STEP standard data model to integrate themanufacturing and inspection processes. The application protocol AP219 of the ISO 10303standard defines the context, scope and information requirements necessary to analyze andreport dimensional inspection results, creating a mechanism for bidirectional exchange ofinformation with other data models used in the product life cycle such as AP242, AP224 andAP238 application protocols.The UoF functional limitations included in the AP219 has the harmonized entities thatallow to define both the value of the deviation acceptable for the manufacture of the piece andthe dimensional tolerances. The tolerances are applied to the elements defined within the entityshape aspect. Geometric tolerance is the maximum or minimum variation given for a positionXXII World Congress of the International Measurement Confederation (IMEKO 2018)IOP Conf. Series: Journal of Physics: Conf. Series 1065 (2018) 082014IOP Publishingdoi:10.1088/1742-6596/1065/8/0820144Design SystemCADProcess Planning SystemCAPPCAIP+-Compensation System CAM++PartCNC ControllerClosed-Loop InspectionEData Validation+ -12 34QIF - PlansQIF - RulesQIF - ResourcesQIF - MBDInspection  DataMeasurement PlanCAD model nominalQIF-ResultsQIF-StatisticsMeasurement ExecutionTolerance AnalyseserrorQIF and ISO 10303-238QIF(Quality Information Framework) ISO 10303-203, 214, 219 and 242ISO 10303-238Nominal/actual comparison  and analysis1234ComparatorNominal/actualcomparison and analysisFigure 2. Feedback strategy within the closed-loop inspection.or geometric shape in the manufacturing process. The entity Geometric tolerance is used todefine and exchange the data of the critical requirements of a piece by means of the conceptof tolerance feature represented within the STEP standard as an attribute of shape aspect tospecify a type of geometric feature.5. ConclusionsThe dimensional and geometric inspection allows implementing strategies to perfect themanufacturing processes using correctly the obtained information. The feedback strategyproposed in the article avoids the loss of information produced by format changes betweensystems because it uses a neutral data structure with homogenized syntax and semantics fordifferent processes of the one-piece manufacturing life cycle. Automated operations, optimizationtechniques, and expert systems for decision-making can be easily implemented.References[1] X. Xu, Integrating advanced computer-aided design, manufacturing, and numerical control: principles andimplementations. Information Science Reference-Imprint of: IGI Publishing, 2009.[2] J. Lee, B. Bagheri, and H.-A. Kao, “A cyber-physical systems architecture for industry 4.0-basedmanufacturing systems,” Manufacturing Letters, vol. 3, pp. 18–23, 2015.[3] P. Hu, Z. Han, H. Fu, and D. Han, “Architecture and implementation of closed-loop machining system basedon open step-nc controller,” The International Journal of Advanced Manufacturing Technology, vol. 83, no.5-8, pp. 1361–1375, 2016.[4] F. Zhao, X. Xu, and S. Xie, “Step-nc enabled on-line inspection in support of closed-loop machining,” Roboticsand Computer-Integrated Manufacturing, vol. 24, no. 2, pp. 200–216, 2008.[5] R.-x. Xia, R.-s. Lu, Y.-q. Shi, Q. Li, J.-t. Dong, and N. Liu, “Caip system for vision-based on-machine measurement,” in Seventh International Symposium on Precision Engineering Measurements andInstrumentation, vol. 8321. International Society for Optics and Photonics, 2011, p. 83213V.[6] P. Wilma and M. Giovanni, “A frame for a computer aided inspection planning system,” International Journalof Engineering & Technology, vol. 4, no. 1, p. 125, 2015.

Feedback strategy for closed-loop inspection based on STEP-NC

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Feedback strategy for closed-loop inspection based on STEP-NC

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