MScMS-II: an innovative IR-based indoor coordinate measuring system for large-scale metrology applications

According to the current great interest concerning large-scale metrology applications in many different fields of manufacturing industry, technologies and techniques for dimensional measurement have recently shown a substantial improvement. Ease-of-use, logistic and economic issues, as well as metrological performance are assuming a more and more important role among system requirements. This paper describes the architecture and the working principles of a novel infrared (IR) optical-based system, designed to perform low-cost and easy indoor coordinate measurements of large-size objects. The system consists of a distributed network-based layout, whose modularity allows fitting differently sized and shaped working volumes by adequately increasing the number of sensing units. Differently from existing spatially distributed metrological instruments, the remote sensor devices are intended to provide embedded data elaboration capabilities, in order to share the overall computational load. The overall system functionalities, including distributed layout configuration, network self-calibration, 3D point localization, and measurement data elaboration, are discussed. A preliminary metrological characterization of system performance, based on experimental testing, is also presente

Study of optical techniques for the Ames unitary wind tunnels. Part 4: Model deformation

A survey of systems capable of model deformation measurements was conducted. The survey included stereo-cameras, scanners, and digitizers. Moire, holographic, and heterodyne interferometry techniques were also looked at. Stereo-cameras with passive or active targets are currently being deployed for model deformation measurements at NASA Ames and LaRC, Boeing, and ONERA. Scanners and digitizers are widely used in robotics, motion analysis, medicine, etc., and some of the scanner and digitizers can meet the model deformation requirements. Commercial stereo-cameras, scanners, and digitizers are being improved in accuracy, reliability, and ease of operation. A number of new systems are coming onto the market

Railway freight transport and logistics: Methods for relief, algorithms for verification and proposals for the adjustment of tunnel inner surfaces

In Europe, the attention to efficiency and safety of international railway freight transport has grown in recent years and this has drawn attention to the importance of verifying the clearance between vehicle and lining, mostly when different and variable rolling stock types are expected. This work consists of defining an innovative methodology, with the objective of surveying the tunnel structures, verifying the clearance conditions, and designing a retrofitting work if necessary. The method provides for the use of laser scanner, thermocameras, and ground penetrating radar to survey the geometrical and structural conditions of the tunnel; an algorithm written by the authors permits to verify the clearances. Two different types of works are possible if the inner tunnel surfaces interfere with the profile of the rolling stock passing through: modification of the railroad track or modification of the tunnel intrados by mean milling of its lining. The presented case study demonstrates that the proposed methodology is useful for verifying compatibility between the design vehicle gauge and the existing tunnel intrados, and to investigate the chance to admit rolling stocks from different states. Consequently, the results give the railway management body a chance to perform appropriate measurements in those cases where the minimum clearance requirements are not achieved

IR Thermometer with Automatic Emissivity Correction

The paper describes the design and implementation of an infrared (IR) thermometer with automatic emissivity correction. The temperature measurement is carried out by the simple digital thermopile sensor MLX90614. The emissivity correction is based on benefits of diffuse reflecting materials and it uses an IR laser diode in conjunction with a selective amplifier. Moreover, the paper includes the design of the control interface with a graphics LCD. Furthermore, this paper describes the power supply unit with a Li-ion cell controlled by basic integrated circuits

Frequency-modulated continuous-wave LiDAR compressive depth-mapping

We present an inexpensive architecture for converting a frequency-modulated continuous-wave LiDAR system into a compressive-sensing based depth-mapping camera. Instead of raster scanning to obtain depth-maps, compressive sensing is used to significantly reduce the number of measurements. Ideally, our approach requires two difference detectors. % but can operate with only one at the cost of doubling the number of measurments. Due to the large flux entering the detectors, the signal amplification from heterodyne detection, and the effects of background subtraction from compressive sensing, the system can obtain higher signal-to-noise ratios over detector-array based schemes while scanning a scene faster than is possible through raster-scanning. %Moreover, we show how a single total-variation minimization and two fast least-squares minimizations, instead of a single complex nonlinear minimization, can efficiently recover high-resolution depth-maps with minimal computational overhead. Moreover, by efficiently storing only $2m$ data points from $m<n$ measurements of an $n$ pixel scene, we can easily extract depths by solving only two linear equations with efficient convex-optimization methods

A laser tracking dynamic robot metrology instrument

Research work over several years has resulted in the development of a laser tracking instrument capable of dynamic 3-D measurements of robot end-effector trajectories. The instrument characteristics and experiments to measure the static and dynamic performance of a robot in an industrial manufacturing environment are described. The use of this technology for space applications is examined

Multi-wavelength, multi-beam, photonic based sensor for object discrimination and positioning

Over the last decade, substantial research efforts have been dedicated towards the development of advanced laser scanning systems for discrimination in perimeter security, defence, agriculture, transportation, surveying and geosciences. Military forces, in particular, have already started employing laser scanning technologies for projectile guidance, surveillance, satellite and missile tracking; and target discrimination and recognition. However, laser scanning is relatively a new security technology. It has previously been utilized for a wide variety of civil and military applications. Terrestrial laser scanning has found new use as an active optical sensor for indoors and outdoors perimeter security. A laser scanning technique with moving parts was tested in the British Home Office - Police Scientific Development Branch (PSDB) in 2004. It was found that laser scanning has the capability to detect humans in 30m range and vehicles in 80m range with low false alarm rates. However, laser scanning with moving parts is much more sensitive to vibrations than a multi-beam stationary optic approach. Mirror device scanners are slow, bulky and expensive and being inherently mechanical they wear out as a result of acceleration, cause deflection errors and require regular calibration. Multi-wavelength laser scanning represent a potential evolution from object detection to object identification and classification, where detailed features of objects and materials are discriminated by measuring their reflectance characteristics at specific wavelengths and matching them with their spectral reflectance curves. With the recent advances in the development of high-speed sensors and high-speed data processors, the implementation of multi-wavelength laser scanners for object identification has now become feasible. A two-wavelength photonic-based sensor for object discrimination has recently been reported, based on the use of an optical cavity for generating a laser spot array and maintaining adequate overlapping between tapped collimated laser beams of different wavelengths over a long optical path. While this approach is capable of discriminating between objects of different colours, its main drawback is the limited number of security-related objects that can be discriminated. This thesis proposes and demonstrates the concept of a novel photonic based multi-wavelength sensor for object identification and position finding. The sensor employs a laser combination module for input wavelength signal multiplexing and beam overlapping, a custom-made curved optical cavity for multi-beam spot generation through internal beam reflection and transmission and a high-speed imager for scattered reflectance spectral measurements. Experimental results show that five different laser wavelengths, namely 473nm, 532nm, 635nm, 670nm and 785nm, are necessary for discriminating various intruding objects of interest through spectral reflectance and slope measurements. Various objects were selected to demonstrate the proof of concept. We also demonstrate that the object position (coordinates) is determined using the triangulation method, which is based on the projection of laser spots along determined angles onto intruding objects and the measurement of their reflectance spectra using an image sensor. Experimental results demonstrate the ability of the multi-wavelength spectral reflectance sensor to simultaneously discriminate between different objects and predict their positions over a 6m range with an accuracy exceeding 92%. A novel optical design is used to provide additional transverse laser beam scanning for the identification of camouflage materials. A camouflage material is chosen to illustrate the discrimination capability of the sensor, which has complex patterns within a single sample, and is successfully detected and discriminated from other objects over a 6m range by scanning the laser beam spots along the transverse direction. By using more wavelengths at optimised points in the spectrum where different objects show different optical characteristics, better discrimination can be accomplished

NON-CONTACT SPATIALLY CONSTRAINED OPTICAL SCANNING METHODS APPLIED FOR DEPTH, WIDTH AND GAP MEASUREMENTS

The thesis presents the non-contact laser projection based systems utilized for quantifying the feature dimensions like width, depth and air gaps. Laser diode, Charge coupled device (CCD) and post-processing software using image processing tools are the major components of the non-contact measurement systems. The study involves two methods where the first method comprises of active laser-based triangulation and morphological edge detection for depth and width measurement applications. The second method uses edge detection technique and Dynamic Field of View (DFOV) for gap detection and tracking. Using the developed techniques, the case studies are conducted with smooth plastic fenders with induced artificial deviations, MIG welding seam and different air gap deco finishes. Experimental validations are carried out by comparing the results with commercial systems like 3D scanner and commercial sensor. Also, the Gauge Repeatability and Reproducibility (GR&R) studies are produced to identify the gap measurement tool capabilities interms of accuracy and repeatability