Contact-free Measurement System Research Articles

Measurement of Material Flow in Series Production

This paper provides first results of a contact-free measurement system for monitoring the material flow in series production which has been under investigation for more than one year. An inductive proximity sensor with analog output was used to measure its own sheet metal coverage. Multiple sensors were integrated in the blank holder without affecting the deep drawing process. The robustness of the monitoring principle was assessed under series production conditions by using optical measurement equipment. This paper describes the basic information of the inductive measurement, the comparison of the inductive and optical measurement results and analyses correlations between the sensors.

Remote Sensor for Spatial Measurements by Using Optical Scanning

In this paper, we propose a low-cost contact-free measurement system for both 3-D data acquisition and fast surface parameter registration by digitized points. Despite the fact that during the last decade several approaches for both contact-free measurement techniques aimed at carrying out object surface recognition and 3-D object recognition have been proposed, they often still require complex and expensive equipment. Therefore, alternative low cost solutions are in great demand. Here, two low-cost solutions to the above-mentioned problem are presented. These are two examples of practical applications of the novel passive optical scanning system presented in this paper.

Contact-free measurements and numerical analyses of the strain distribution in the joint area of steel-to-timber dowel joints

Two different dowel-type joints of differing size were loaded in tension parallel to the grain. The strain distribution in the joint area was studied using a contact-free measurement system. The results were compared with those of numerical analysis. The measurement system was found to be a valuable complement to traditional measurement techniques and also to numerical analyses performed in parametric studies. The measurements obtained were shown to be particularly useful for studying the highly nonlinear behavior of timber that is of special importance in characterizing timber dowel joints. Several observations of considerable interest were made on the basis of numerical results in combination with results of the contact-free measurement system. A non-uniform strain distribution in the joint area was detected, for example, and shear strains and tensile strains, both parallel and perpendicular to the grain were found to be concentrated in the areas most likely to influence the failure mode of the joint. A general observation made was that the larger size joint failed in brittle manner, an observation supported by previous research.

Contact-free measurement and non-linear finite element analyses of strain distribution along wood adhesive bonds

Abstract The strain distribution along wood adhesive bonds was studied using a contact-free measurement system based on a white-light digital image correlation (DIC) technique. Two different specimen geometries and three different adhesives were investigated. The specimen geometries were according to the standards EN302-1 and ASTM D905. The adhesives tested were a phenolic resorcinol (PRF), a one-component polyurethane (PUR) and an epoxy (EPX). In addition to the experimental investigation, a finite element study using a non-linear fracture mechanics model for the adhesive bond line was carried out, aimed at investigating whether deformation measurements could predict differences in the mechanical behaviour of the adhesives. The measurement technique was found to be capable of distinguishing, in terms of their strain distributions at a given load, adhesives that differed markedly from one another. For example, the brittle PRF adhesive showed more localised strains than the more ductile EPX and PUR adhesives did at the same load level. Another conclusion from this study is that the measurement technique used is applicable to situations in which large strains occur. Thus, the technique used here is of great interest for use in the calibration of finite element models and constitutive theories and for the design of test set-ups.

Augmented reality based on auto-stereoscopic display for computer-aided surgery

We present a video-based, contact-free measurement system which allows combined tracking of the subject's eye positions and the gaze direction in near real time. This system will be integrated into a new kind of autostereoscopic display which supports the natural link between accommodation and convergence of human vision, reproduces the limited depth of focus of human vision and shows comfortable, hologram-like scenes with motion parallax to subjects.

Eye and gaze tracking for visually controlled interactive stereoscopic displays

We present a video-based, contact-free measurement system which allows combined tracking of the subject's eye positions and the gaze direction in near real time. This system will be integrated into a new kind of autostereoscopic display which supports the natural link between accommodation and convergence of human vision, reproduces the limited depth of focus of human vision and shows comfortable, hologram-like scenes with motion parallax to subjects.