Integration In Production Lines Research Articles

A System for In-Line 3D Inspection without Hidden Surfaces

This work presents a 3D scanner able to reconstruct a complete object without occlusions, including its surface appearance. The technique presents a number of differences in relation to current scanners: it does not require mechanical handling like robot arms or spinning plates, it is free of occlusions since the scanned part is not resting on any surface and, unlike stereo-based methods, the object does not need to have visual singularities on its surface. This system, among other applications, allows its integration in production lines that require the inspection of a large volume of parts or products, especially if there is an important variability of the objects to be inspected, since there is no mechanical manipulation. The scanner consists of a variable number of industrial quality cameras conveniently distributed so that they can capture all the surfaces of the object without any blind spot. The object is dropped through the common visual field of all the cameras, so no surface or tool occludes the views that are captured simultaneously when the part is in the center of the visible volume. A carving procedure that uses the silhouettes segmented from each image gives rise to a volumetric representation and, by means of isosurface generation techniques, to a 3D model. These techniques have certain limitations on the reconstruction of object regions with particular geometric configurations. Estimating the inherent maximum error in each area is important to bound the precision of the reconstruction. A number of experiments are presented reporting the differences between ideal and reconstructed objects in the system.

List of abstracts

. Results obtained in the analysis of single layer and multilayered carbon stacks produced by PLD at low temperature will be presented. The mechanical properties of carbon single layers deposited at various laser pulse fluences, like hardness and elasticity, were determined by means of nano indentation measurements. It will be shown that a wide variety of mechanical properties can easily be adjusted by adapting the process parameters.

Measurement of Aerodynamic Coefficients of Spherical Objects Using an Electro-optic Device

Aerodynamic coefficients are required to determine the trajectory of moving objects. These coefficients are typically obtained measuring the forces acting on the object using a wind tunnel. Wind tunnels are expensive and not easily available; therefore, their use is limited. This paper presents a new procedure to measure aerodynamic coefficients of spherical objects using an electro-optic device. Forces are calculated from velocity changes instead of being directly measured. The procedure is based on a method to measure the three components of the instantaneous velocity vector at known positions. The main advantages are size, cost and complexity reduction compared to wind tunnels. These advantages open the possibility of integration in production lines for quality control. A prototype has been built and tested using soccer balls.

Emat Pipe Inspection with Guided Waves

Electro Magnetic Acoustic Transducers (EMATs) are a well-known type of ultrasonic probes used for nondestructive evaluation (NDE) of electrically conductive materials. Conventional Ultrasonic Testing (UT) is performed by longitudinal waves and mode converted shear waves generated by piezoelectric probes. EMATs are broadening the range of usable wave modes by the direct conversion of polarized shear waves with normal and angle beams and the selective generation and detection of nearly all types of guided waves. Despite their limitations (low efficiency, lift-off sensitivity, limited frequency range etc.) they have the big advantage to perform UT without couplants. The dry coupling allows UT at elevated temperatures, in media which do not tolerate liquids (e.g. natural-gas pipelines) or on sensitive and coated surfaces of blanks used for car bodies in the automotive industry etc. Ultrasonic Testing (UT) is still concentrated on the ‘classical’ wave modes generated by piezoelectric probes. Other wave modes as the Shear Horizontal (SH) waves and the wide class of guided waves offer new solutions for UT not yet widely used due to the lack of availability of appropriate probes and equipment. EMATs are the most far developed ultrasonic probes for UT using SH waves and guided waves. This contribution will present new solutions for UT of pipes using guided waves such as Shear Horizontal waves: for weld inspection, for long range inspection of pipes, for screening UT for hidden corrosion, for crack inspection in gas pipelines. The latest developments of the probe design are briefly reported. The equipment and their integration in production lines for in-service application are shown together with examples of inspection results during their practical applications.

Magneto-Optical Characterization of Colloidal Dispersions. Application to Nickel Nanoparticles

We report here on a fast magneto-optical characterization method for colloidal liquid dispersions of magnetic nanoparticles. We have applied our methodology to Ni nanoparticles with size equal or below 15 nm synthesized by a ligand stabilized solution-phase synthesis. We have measured the magnetic circular dichroism (MCD) of colloidal dispersions and found that we can probe the intrinsic magnetic properties within a wide concentration range, from 10(-5) up to 10(-2) M, with sensitivity to concentrations below 1 microg/mL of magnetic Ni particles. We found that the measured MCD signal scales up with the concentration thus providing a means of determining the concentration values of highly diluted dispersions. The methodology presented here exhibits large flexibility and versatility and might be suitable to study either fundamental problems related to properties of nanosize particles including surface related effects which are highly relevant for magnetic colloids in biomedical applications or to be applied to in situ testing and integration in production lines.

Ergonomics and knowledge management for process control

For process control, it is important for operators to understand and trust the messages. To enable this, it is important to understand not only the content but also the logic, behind the message. Similarly, to develop feed-forward controls that achieve some level of production line integration, the logic for the controls must be adapted to local conditions. The logic may also have to be adapted for different products and for other factors such as seasonal changes and even day-night changes. These sorts of changes can only be managed on the shop floor. The presentation will discuss how expert systems, desk-top publishing and object orientation can be combined to develop a shared understanding of the logic of the process control system and its component parts, so that people from operations, including supervisors on the shop floor, can be involved in managing and adapting the logic to local requirements.