Fig 7 - uploaded by Luciana Cristea
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Serial peripheral interface between the microcontroller Atmega 8535 and weight conversion integrated circuit AD7730.
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The new production has to undertake a continuous quality improvement due to its major economic involvement; the consequence consists in high performances in the quality assurance. Therefore the author of this work wants to present some concerns in the automatic dimensional inspection systems field. The new production has to undertake a continuous q...
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... microcontroller receives trough the SPI (Serial Peripheral Interface) interface the results of the analogue-digital conversion (ADC) and the integrated circuit that realizes the conversion (AD7730) is made by Analogue Devices and is responsible with the processing of the information collected from the weight resistive transducer. Figure 7 shows an interface between the AD7730 and the ATmega8535 microcontroller. The diagram shows the minimum (three-wire) interface with CS on the AD7730 hardwired low. ...
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Citations
... The principal component analysis of WPCA, and the Hotelling control limit of WHS,individually judges the existence of defects. Cristea[13] presents aspects of the design for an intelligent modular inspection system. This system consists of grouping the parts based on the relation between dimensional inspection process characteristics and modular design of all inspection equipments with a high universality and flexibility degree. ...
Dimensioning and tolerancing standards assume inspection operation, unless otherwise specified, must be done in Free State. This can be problematic when dealing with compliant parts. The inspection of compliant parts needs specialized fixtures because in Free State they may have a significantly different form than their nominal model (CAD) due to inherent variations in the manufacturing process, gravity loads, and residual strains. These specialized fixtures pose difficulties, bear significant costs to industry, and the process is very time-consuming. To address these challenges, this paper proposes a new method for quantifying flexibility/rigidity of the mechanical parts. Subsequently, a novel approach named IDB-CTB is proposed to fixtureless inspection of deformable bodies by curvature estimation and Thompson-Biweight test. This approach combines the Gaussian curvature properties of manufactured compliant parts, one of the intrinsic properties of the geometry, with the Thompson-Biweight statistical test based on the extreme value notion as an identification method. The aim is to distinguish profile deviation due to the manufacturing process from a part’s deformation due to its flexibility in order to determine whether the tolerance fits the CAD model or not. The IDB-CTB approach is tested on two sets of case studies. Three simulated, typical industrial sheet metal case studies were performed in the first set, and an experimental case study in the second one. The low percentage of errors in defect areas and in the profile deviations estimated compared with their reference ones in most cases reflects the effectiveness of the proposed approach.
... exploredautomatedvisualinspection ofsurfacedefectsinalight-emittingdiode(LED) chipbyapplyingwavelet-basedprincipal componentanalysis(WPCA)andHotellingstatistic (WHS)approachestointegratethemultiplewavelet characteristics.Theprincipalcomponentanalysisof WPCAandtheHotellingcontrollimitofWHS individuallyjudgetheexistenceofdefects.Cristea [8]presentsaspectsofthedesignforanintelligent modularinspectionsystem.Thissystemconsistsof groupingthepartsbasedontherelationbetween dimensionalinspectionprocesscharacteristicsand modulardesignofallinspectionequipmentswitha highuniversalityandflexibilitydegree. Fig.4 ...
... The principal component analysis of WPCA and the Hotelling control limit of WHS individually judge the existence of defects. Cristea [8] presents aspects of the design for an intelligent modular inspection system. This system consists of grouping the parts based on the relation between dimensional inspection process characteristics and modular design of all inspection equipments with a high universality and flexibility degree. ...
Non-rigid parts, in free-state, may have a considerable different shape than their nominal model due to dimensional and geometric variations of manufacturing process, gravity loads and residual stress induced distortion. Therefore, sorting profile deviation from a part's deformation by comparing the part's nominal shape to its scanned free-state shape is a challenging task. This task is a key step in the Iterative Displacement Inspection (IDI) algorithm used for the inspection of non-rigid parts without the use of costly specialized fixtures. This paper proposes the use of the statistical maximum normed residual test to improve the aforementioned identification task. Thirty two simulated manufactured parts are studied to show that the proposed method reduces the type I and II identification error of the IDI method.
The main purpose of this research is to generate optimised feeding, transport, and proportioning and alignment systems for more mechanical efficiency of automation system. The basic idea underlying this research is to organize a complex system as a set of distinct components that can be independently developed and then plugged together to obtain an integrated mechatronic system for dimensional inspection.
In this thesis, we focus on the automation of the fixtureless geometric inspection of non-rigid (or compliant) parts. The primary objective of this project is to handle virtually this type of component and their point cloud, which represents a scan taken in a Free State condition, by eliminating the use of very expensive and complicated specialized fixtures posing productivity problems for manufacturing companies. This topic is a very high interest in the transport sector and, more specifically, in the aerospace one in order to significantly improve its productivity and its degree of competitiveness. The thesis is organized by articles. The study is divided over four phases. The first three phases will be represented by three journal papers and the fourth phase is presented as an appendix. The first phase of this work is intended to improve the identification module of an existing inspection mathematical tool « IDI: The Iterative Displacement Inspection » which has been developed by the research team working under the supervision of professor Tahan at ÉTS. The identification module aims to distinguish between defects that are due to the manufacturing process and deformations that are due to the flexibility of the part (gravity and residual stress effects). We propose to replace the original module with a new one which is based on the extreme value statistical analysis. We demonstrate that the new module remarkably reduces the type I and type II errors. In addition, unlike the identification method of the IDI, the proposed one does not require a user-specified threshold based on a trial and error process. In the second phase of this study, we propose an original approach to measure the flexibility/rigidity of the mechanical components. We introduce a factor that represents the ratio between the maximum displacement resulting from the deformation of the part and its profile tolerance and we present the results in a logarithmic scale. Three different régions were defined as giving a clear idea to the manufacturing industry about the situation of the parts on the flexibility scale. Subsequently, we propose a new fixtureless inspection method for compliant parts: the IDB-CTB « Inspection of Deformable Bodies by Curvature and Thompson-Biweight » method. This approach combines the Gaussian curvature estimation, one of the intrinsic properties of the surface which is invariant under isometric transformations, with an identification method based on the extreme value statistics (Thompson-Biweight Test). The low percentage error in defect areas and in profile deviations estimated reflects the effectiveness of our approach. In the third phase of this thesis, we propose a novel method that can be considered as complementary to the IDB-CTB approach. In addition to the profile deviations, we aim to detect the localization defects. We introduce two criteria that correspond to the specification of compliant parts: the conservation of the curvilinear distance and the minimization between two objects (Hausdorff Distance). We adapt and automate the Coherent Point Drift; a powerful non-rigid registration algorithm widely used in medical imagery and animation, for satisfying these two criteria. We obtain satisfying results by applying the third approach on a typical aerospace sheet metal. The conclusion of this thesis summarizes the scientific contributions through our work on the fixtureless inspection of compliant parts and the perspective related with it. In the appendix, we introduce a graphical user interface (GUI) created to handle the proposed approaches as well as the case studies bank developed in the training at Bombardier Aerospace Inc.
Non-rigid parts in free state condition may have a different form than their nominal CAD model due to dimensional variation, gravity loads, residual stress induced distortion and/or assembly force. The Iterative Displacement Inspection (IDI) algorithm has been developed in order to resolve this problematic. In this paper we propose an improving of the identification techniques used to distinguish between the defects due to the manufacturing process and the deformations due to the positioning of the part and its flexibility. The maximum normed residual test has been implemented in the identification module of the IDI algorithm. A quasi-constant surface, an omega shape and a freeform surface representing typical structure parts in the transport industry are tested, giving satisfying results in most cases.
