Algorithms for automated inspection

Mechanical Engineering Research, 2011

Industrial inspection is one of the crucial tasks to ensure quality conformance of products. The inspection tasks can be done by using several methods like non-scaled go/not go gauging, measuring instruments, or advanced non-touching tools. In this research visual inspection using a developed optical system is conducted. One of the aims of this research is to design an on line visual inspection system that is capable to test geometrical quality characteristics of 2-D machined products. The design process includes developing an economical optical system to acquire inspected product's images. Image processing tools are utilized to deal with the product image; and extract features of its geometrical characteristics. A neural network-based methodology is developed and applied to decide whether the product conforms to pre-specified tolerances. The results of the developed methodology are compared to some statistics based visual approaches from the literature. The results show the goodness of the system as an automated visual inspection system and prove its superior performance with respect to other methods.

2013

In manufacturing industry, machine vision is very important nowadays. Computer vision has been developed widely in manufacturing for accurate automated inspection. A model of automated inspection system is presented in this conceptual paper. Image processing is used for inspection of part. It is assumed that the part after going through many previous operations comes to inspection system where the weight of the part as well as geometry made on that part is detected and later decided whether it is to be accepted or rejected with the help of image processing technique. Using MATLAB software a program is developed and pattern or geometry is detected.

International Journal on Interactive Design and Manufacturing (IJIDeM), 2012

In the last few years the need for methodologies capable of performing an automated geometric inspection has increased. These methodologies often use 3D highresolution optical digitisers to acquire points from the surface of the object to be inspected. It is expected that, in the near future, geometric inspection will be requiring more and more the use of these instruments. At present geometric inspection is not profiting from all the opportunities attainable by 3D high-resolution optical scanners or from the numerous tools which can be used for processing the point cloud acquired from the inspected product. For some years now, these authors have been working on a new methodology for automatic tolerance inspection working from a 3D model acquired by optical digitisers. In this paper all the information recognisable in a scanned object is organised into a new data structure, called Recognised Geometric Model (RGM). The final aim is to define a representation of the inspected object for the automatic evaluation of the nonidealities pertaining to the form, orientation and location of the non-ideal features of the acquired object. The key concept of the proposed approach is the capability to recognise some intrinsic nominal properties of the acquired model. These properties are assumed as references to evaluate the non-idealities of the inspected object. With this approach the references of geometric inspection are searched for in the inspected object independently of a tolerance specification and of the availability of a 3D nominal representation. The high-level geometric information within RGM depends on the rules used for its identification. The capability to recognise specific categories of nominal references offers the possibility of introducing new tolerances to be specified. The proposed approach has been implemented in original software by means of which a specific test case has been analysed.

Inspection and dimensional measurement of machined parts plays a vital role in manufacturing. Machined parts are inspected to much tighter tolerances in order to achieve the highest quality finished products. The dimensional inspection process of discrete components has been developed and automated with time and has come a long way, from the early use of gauge blocks, dial indicators, micrometers to today's computer controlled coordinate measuring machines (CMMs) with touch trigger probes. Despite this rapid advancement, bespoke inspection methods are used for dimensional measurement of machined parts either on a CMM or a CNC machining centre have touch trigger probes. A generalised dimensional inspection framework is required and to achieve this STEP and STEP-NC standards provide a convenient plate-form. In this paper the concept of a framework which gives a generalised feature-based inspection and measurement plan for prismatic machined parts based on STEP and STEP-NC is presented. This generalised STEP-NC compliant inspection plan could be a direct input to an intelligent controller of a CNC machining centre through an interface or can be interpreted into an inspection code for a CMM. The inspection framework uses the information regarding manufacturing features of a machined part and touch probing as given in ISO14649 (STEP-NC).

During the post-manufacturing life-cycle(assembling, packaging,…) the object surface could interact with other surfaces modifying its morphology with the introduction of local damages (scratches, bumps,…). Following quality principles and especially working with aesthetic components it is very important to detect these defects on the objects surface in order to fix it and to grant to the costumer a acceptable product. While for elementary geometries the inspection procedure are already standardized, working with sculptured ones (FREE-FORM), typical of the aesthetic components, the shape inspection strategies are not so known. In fact normally working on single components the inspection phase can be implemented manually by an expert operator that develop a complete visual inspection of the surface. But moving the attention on automated production lines this manual approach has to be substituted by an automatic one. So starting from the experience developed with reverse engineering and 3D scanner systems this work wants to propose an automated inspection strategy based on a segmentation reverse engineering strategy.

1999

The recent requirement for increased speed in the design and manufacturing of new products led to a rapid evolution of the technics for fast production (rapid prototyping, machining at high speed, etc.). But a significant component did not follow this evolution, that is the dimensional and functional checking process. To automate this significant phase of production, it is necessary to develop some new analysis method. We presented an inspection method designed around three modules: a first one registrates the CAD model of a part and its 3D data obtained with an active optical range sensor, the second module segments the homogeneous cloud of 3D points in areas representing each surface of the object, and the third one is a visual check of the dimensions of the part. RÉSUMÉ.La nécessité récente d’augmenter la vitesse de conception et de réalisation de nouveaux produits a permis de développer de nouvelles techniques de production rapide (prototypage rapide, usinage à très grande vites...

Sensors

Automatic measurements via image processing can accelerate measurements and provide comprehensive evaluations of mechanical parts. This paper presents a comprehensive approach to automating evaluations of planar dimensions in mechanical parts, providing significant advancements in terms of cost-effectiveness, accuracy, and repeatability. The methodology employed in this study utilizes a configuration comprising commonly available products in the industrial computer vision market, therefore enabling precise determinations of external contour specifications for mechanical components. Furthermore, it presents a functional prototype for making planar measurements by incorporating an improved subpixel edge-detection method, thus ensuring precise image-based measurements. The article highlights key concepts, describes the measurement procedures, and provides comparisons and traceability tests as a proof of concept for the system. The results show that this vision system did achieve suitab...

2000

Structured light is one of the well-known methods in part dimensional inspection that have been successfully employed in various applications in the past decades. In this method, the positioning of the camera is very critical, which a ects the accuracy and e ciency of the whole inspection system. Here we develop a CADguided camera positioning system to aid the 3-D part inspection. The geometric information in the CAD model of the inspected p art and the camera m o del are used to plan camera c on gurations that satisfy certain task constraints. The overall system we propose can be applied to the 3-D inspection of parts with free-form surfaces, such as automobile door panels. Experiments on di erent parts show satisfying results.

Procedia Computer Science, 2021

Quality control (QC) in manufacturing processes is critical to ensuring consumers receive products with proper functionality and reliability. Faulty products can lead to additional costs for the manufacturer and damage trust in a brand. A growing trend in QC is the use of machine vision (MV) systems because of their noncontact inspection, high repeatability, and relatively low cost. This paper presents a robust MV system developed to perform comparative dimensional inspection on diversely shaped samples, including additive manufacturing products. The algorithm used performs dimensional inspection on a base product considered to have acceptable dimensions. The perimeter, area, rectangularity, and circularity of the base product are determined using blob analysis on a calibrated camera. These parameters are then used as the standard with which to judge additional products. Each product following is similarly inspected and compared to the base product parameters. A likeness score is calculated for each product, which provides a single value tracking all parameter differences. Finally, the likeness score is considered on whether it is within a threshold, and the product is considered to be acceptable or defective. The proposed MV system has achieved satisfactory results, as discussed in the results section, that would allow it to serve as a dependable and accurate QC inspection system in industrial settings.

Computer-Aided Design, 2004

Precision inspection has been widely used in manufacturing to measure the dimensional accuracy of parts and products to meet the quality requirements. For regular geometric features, coordinate-measuring machines (CMM) can be used effectively to assess the accuracy and tolerances. For parts with free-form surfaces, the inspection becomes complex. Therefore, numerous researches have been carried out to tackle both fundamental and application issues concerning free-form surface inspection. In addition to academic research, some commercial packages have also been developed. This paper provides a comprehensive literature review of methodologies, techniques and various processes of inspections of parts with free-form surfaces. The specific topics cover: measurement data acquiring methods including contact and non-contact measurement approaches; inspection planning; geometric description methods of design models or measurement data; and, the free-form surface localization and comparison techniques, which are emphasized in this paper and mainly include the establishment of corresponding relationship, 3D transformation solving, measurement data to design model comparison or surface to surface distance calculations. Other issues, such as the influence factors to the localization/registration process, definition and inspection of free-form surface tolerance, and discussions on the functions of some commercial inspection packages available on market, are also discussed.