VISION HELPS SPOT FAILURES ON THE RAIL – NETWORK RAIL LTD.

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An automated vision inspection system relieves rail workers from the task of manually inspecting rail infrastructure

Traditionally, rail infrastructure has been inspected manually by foot patrols walking the entire length of a rail network to visually determine whether any flaws exist that could result in failures. Needless to say, the method is extremely labor intensive and time consuming.

To minimize the disruption to train services, the manual inspection process is usually performed overnight and at weekends. However, due to the increase in passenger and freight traffic on rail networks, the time that can be allocated to access the rail infrastructure by foot patrols is now at a premium. Hence rail infrastructure owners are under pressure to find more effective means to perform the task.

To reduce the time required to inspect its rail network, UK infrastructure owner Network Rail (London, England; http://www.networkrail.co.uk) is now deploying a new vision-based inspection system that looks set to replace the earlier manual inspection process. Not only will the system help to increase the availability — and assure the safety — of its rail network, it will also enable the organization to determine the condition of the network with greater consistency and accuracy.

Developed by Omnicom Engineering (York, UK; http://www.omnicomengineering.co.uk), the OmniVision system has been designed to automatically detect the same types of flaws that would be spotted by foot patrols. These include missing fasteners that hold the rail in place on sleepers and faults in weak points in the infrastructure such as at rail joints where lengths of rail are bolted together. The system will also detect the scarring of rail heads, incorrectly fitted rail clamps and any issues with welds that join sections of rail together to form one continuous rail.

SYSTEM ARCHITECTURE

The OmniVision system comprises an array of seven 2048 x 1 pixel line scan cameras, four 3D profile cameras, a sweeping laser scanner and two thermal cameras. Fitted to the underside of a rail inspection car, the vision system illuminates the rail with an array of LED line lights and acquires images of the track and its surroundings as the car moves down the track at speeds of up to 125mph (Figure 1). The on-board vision system is complemented by an off-train processing system located at the Network Rail in Derby that processes the data to determine the integrity of the rail network.

For every 0.8mm that the inspection vehicle travels, a pair of three line scan cameras housed in rugged enclosures capture images of each of the rail tracks. Two vertically positioned cameras image the top surface or the head of each of the rails, while the other four are positioned at an angle to capture images of the web of the rail. A seventh centrally-located line scan camera captures images of the area between the two rails from which the condition of the ballast and the rail sleepers and the location and condition of other rail assets that complement the signaling system can be determined.

The cameras transfer image data to frame grabbers in a PC-based 19in rack system on board the train over a Camera Link interface. The frame grabbers were designed in-house to ensure that the data transfer rate from the cameras could be maintained at a rate of approximately 145MBytes/s and that no artifacts within the images are lost through compression. Once captured, the images from each of the cameras are then written to a set of 1TByte solid state drives.

Within the same rugged enclosure as the line scan cameras, the pair of thermal cameras mounted at 45° angles point to the inside web of each of the rails. Their purpose is to capture thermal data at points such as rail joints which can expand and contract depending on ambient temperature. Both the thermal cameras are interfaced via GigE connections to a frame grabber in the on-board 19in rack and the images from them are also stored on 1TByte solid state drives.

Further down the inspection vehicle, two pairs of 3D profile cameras capture a profile of the rails and the area surrounding them for every 200mm that the vehicle travels. Data from the four cameras are transferred to the 19in rack-mounted system over a GigE interface to a dedicated frame grabber and the data again stored on TByte drives. Data acquired by the cameras is used to build a 3D image of the rails and the fasteners used to hold the rails to the sleepers and the ballast around them.

In addition to the line scan, thermal and 3D profile cameras, the system also employs a centrally-mounted sweeping laser scanner situated on the underside of the inspection vehicle which covers a distance of 5m on either side of the rails. Data from the laser scanner – which is transferred to the 19in rack-mounted system over an Ethernet interface and also stored on a set of Terabyte drives – is used to determine whether or not the height of the surrounding ballast on the rail is either too high or deficient.

PROCESSING DATA

In operation, a vehicle fitted with the imaging system acquires around 5TBytes of image data in a single shift over a distance of around 250 miles. Once acquired, the image data from all the cameras is indexed with timing and GPS positional data such that the data can be correlated prior to processing. Data acquired from the cameras during a shift is then transmitted to the dedicated processing environment at Network Rail, where it is transferred onto a 500TByte parallel file storage system at an aggregate data rate of around 2GB/s for a single data set.

Because the image data is tagged with the location and time at which it was acquired, it is possible to establish the start and end of a specific patrol, or part of a single shift. The indexed imagery associated with each patrol is then subdivided into sections representing several hundred meters of rail infrastructure, after which it is farmed out to a dedicated cluster set of Windows-based servers, known as the image processing factory. Once one set of image data relating to one section of rail has been analyzed by the processing cluster of 20 multi-core PC-based servers and the results returned, a following set of data is transferred into the processors until an entire patrol has been analyzed.

To process the images acquired by the cameras, the OmniVision system uses the image processing functions in MVTec’s (Munich, Germany; WWW.MVTEC.COM) HALCON software library. Typically, the images acquired by the line scan cameras are first segmented to determine regions of interest – such as the location of the rail. Once the location of the rail has been found, it is possible to establish an area of interest around the rail where items such as fasteners, clamps and rail joints should be located. A combination of edge detection and shape-based matching algorithms are then used to determine whether a fastener, clamp or rail joint has been identified by comparing the image of the objects with models stored on the database of the system (Figure 2).

To verify that objects such as fasteners or clamp are present, missing, or being obscured by ballast, a more detailed analysis is performed on the data acquired by the 3D profile cameras as a secondary check. To do so, the 3D profile data is analyzed using HALCON’s 3D pattern matching algorithm to determine the 3D position and orientation of the objects even if they are partially occluded by ballast (Figure 3). Should the software be unable to match the 3D data with a 3D model of the object, the potential defect – known as a candidate – is flagged for further analysis and returned to a database for manual verification.

The system can also determine the condition of welds in the rail. As the vision inspection system moves over each of the welds, the line scan cameras capture an image of each one. From the images, the software can perform shape-based matching to identify locations where a potential joint failure may exist. Any potential failure of the weld is also flagged as a potential candidate for further investigation. Similarly, the 3D-based model created from data captured by the laser scanner can also be analyzed by the software to determine if the height of the ballast in and around the track is within acceptable limits.

IDENTIFYING DEFECTS

Through OmniVision’s Viewer application – which runs on a set of eight PCs connected to the server – track inspectors are visually presented with a breakdown of the defects along with the images associated with them. This allows them to navigate through, review and prioritize any defects that the system may have detected. Once a defect has been identified, the operators can then schedule the necessary repairs to be carried out manually by on-track teams.

To date, three Omnicom vision systems have been fitted to Network Rail inspection vehicles and effectively used to determine the condition of the UK’s West Coast mainline network. Currently, two additional systems are being commissioned and by the end of this year, Network Rail plans to roll the system out to cover the East Coast main line between London and Edinburgh and the Great Western mainline from London to Wales. When fully operational, the fleet of inspection vehicles will inspect more than 15,000 miles of Network Rail’s rail network per fortnight, all year round.

TO KNOW MORE ABOUT MACHINE VISION SYSTEM SINGAPORE, CONTACT MVASIA INFOMATRIX PTE LTD AT +65 6329-6431 OR EMAIL US AT INFO@MVASIAONLINE.COM

Source – MVTEC.COM

MV ASIA INFOMATRIX PTE LTD

3 Raffles Place, #07-01 Bharat Building,
Orchard Road
Singapore – 048617
Tel: +65 63296431
Fax: +65 63296432

E-mail: info@mvasiaonline.com / menzinfo@starhub.net.sg

3D-SHAPE GMBH – AT THE FRONTIERS OF FEASIBILITY

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Why 3D-Shape GmbH equips white light interferometers with MIKROTRON CAMERAS

How do you monitor the topography of micro parts when the demands of efficient production require short cycle times and high quality? 3D-Shape GmbH performs complex surface measurements using the principle of white light interferometry, advanced sensors, 3D image processing and powerful camera technology from Mikrotron GmbH.

Fast three-dimensional image processing technologies are becoming more and more important for quality control of complicated components. They are now superior to tactile measurement systems in speed, flexibility, precision and analytical possibilities. In keeping with the adage “a picture is worth a thousand words,” image analysis allows you to discover complex connections and many object parameters at a single glance.

A few years ago, high precision measurements within industrial production lines were unimaginable. Today, reliable quality control with measurement uncertainties of only a few nanometers are possible even with short cycle times. This is true for applications in the electronics, aircraft and automotive industries through to the mold construction of micro parts with highest precision.

THE MEASURING PRINCIPLE OF WHITE LIGHT INTERFEROMETRY

Through rapid innovation cycles in processor and camera technology as well as in precision optics and image processing software, interferometry is increasingly coming into focus. With white light interferometry, the topographies of both rough and smooth objects can be measured and captured in a very precise way. Simply put, the measurement subject and a reference mirror are illuminated by a light source. This is separated into two parts by a semi-transparent mirror (beam splitter).

As the process continues, this results in brightness variations, which are recorded on the image sensor of the camera. These are analyzed by special software and each pixel is assigned a height value. This then creates a highly differentiated profile height in the nanometer range. If the process is carried out at various layers, complex structures are recorded in their full height.

PERFORMING HIGH-SPEED MEASUREMENTS WITH THE HIGHEST PRECISION

Due to its compact design, the Korad3D system can be directly integrated into the production line.

The KORAD3D sensor product family, produced by 3D-Shape GmbH, utilizes the principle of white light interferometry. Their ability to measure fields of 0.24 × 0.18 mm at minimum to 50 × 50 mm at maximum, means they are compact, can be integrated into the production line systems and cover a wide range of applications. They determine flatness and roughness on sealing surfaces, provide 3D imaging of milling and drilling tools, give information on wear on cutting inserts and check the period length and step height of the smallest contacts in electronic devices. The achievable accuracy is directly dependent on the required measurement field size, the optics used and the camera resolution.

The most important factor influencing the measurement accuracy and measurement speed of a KORAD3D system is the performance of the built-in camera. Larger measurement fields are advantageous in ensuring the system can be used for a variety of applications. However, the greater the measurement field, the more inaccurate the measurement. A key requirement for the camera is therefore the megapixel resolution. This is, of course, in addition to other important aspects of image quality such as contrast and noise behavior and the sensitivity of the camera. At the same time, the camera must be able to deliver a high frame rate. In many applications, the entire structure is recorded layer-by-layer, and at very short cycle times within the production line. Doubling the measuring depth, however, also causes twice the measuring time. The resulting large amounts of data need to be addressed. This can only be achieved by a camera that captures and transfers images in real time.

MONITORING WITH KORAD3D IN THE ΜM RANGE

In order to continue processing the ball-grid arrays without errors, it is important to ensure that they are all placed with their top ends inside one area. The bumps in the arrays, arranged like a “nail board,” can be checked with the KORAD3D for different characteristics up to the µm range.

Every single contact pin in the ball-grid array is precisely checked in size and shape to the µm range. In just about one second, the topography of the entire group is captured.

CONVINCING ON ALL LEVELS

When 3D-Shape were looking for a camera that meets all these requirements best, only a few were shortlisted. The Erlangen-based company operates along the frontier of the physically possible and therefore needed a camera with the latest technology. They got a crucial tip from a sensor manufacturer. According to the head of development, ultimately the Mikrotron EoSens® was the only camera that met all the requirements. Therefore, the company decided to equip the KORAD3D measuring systems family with this camera.

At a full-screen resolution of 1,280 × 1,024 pixels, the camera delivers up to 500 images per second via the high performance base/full-camera link (160/700 MB/second) interface. This specification convinced the Erlangen-based company. So they could monitor the as yet unfitted circuit boards at a frame rate of 180 fps (frames per second) for a customer in the electronics industry. But even higher frame rates of up to 500 fps are used in applications.

Another important argument for the EoSens® was its outstanding light sensitivity of 2,500 ASA. It is based among other things on the large area of a single pixel of 14 × 14 µm and the high pixel fill factor of 40%. The investment required for lighting systems was thus reduced and a higher range of brightness and contrast for image processing could be set.

In addition to this there was the switchable exposure optimization. It adapts the usually linear image dynamics of the CMOS sensors to the nonlinear dynamics of the human eye at two freely selectable levels. The bright areas are thereby suppressed and details can be extrapolated even with extreme light-dark differences in all areas. In the most demanding image processing tasks, this is a great advantage.

Given the cycle times the KORAD3D system has to maintain, each contribution to the acceleration of the data processing is important. This includes the ROI function, which can be defined and customized freely to fit the size and location of individual tasks or the receptive field to be evaluated. The amounts of data are thus reduced and the analysis is accelerated. This simultaneously allows extremely increased frame rates. The built-in multiple ROI function allows the user to define up to three different image fields in the overall picture. 3D-Shape GmbH is not making use of this in current applications, but is already looking at interesting solutions applying this in future.

To keep the measurement accuracy of the topographies created by the KORAD3D system in a narrow range, a number of features of the imaging quality must work together to form a performance-boosting whole. The global shutter of the EoSens® completely freezes the captured frame and stores it in real time, while the next image is already being exposed. This provides images of dynamic processes free of distortion and smear effects. In addition to the C-Mount lens mount there is also the F-Mount option. The latter allows the operator to connect the camera and lens to a fixed calibrated unit, which increases the precision of the analysis. In addition to this range of outstanding performance data the compact design of the camera, which simplifies system integration, wins customers over.

TO KNOW MORE ABOUT MIKROTRON HIGH SPEED CAMERA, SINGAPORE, CONTACT MVASIA INFOMATRIX PTE LTD AT +65 6329-6431 OR EMAIL US AT INFO@MVASIAONLINE.COM

Source – MIKROTRON.DE

MV ASIA INFOMATRIX PTE LTD

3 Raffles Place, #07-01 Bharat Building,
Orchard Road
Singapore – 048617
Tel: +65 63296431
Fax: +65 63296432

E-mail: info@mvasiaonline.com / menzinfo@starhub.net.sg

XENICS AT BIOS AND PHOTONICS WEST 2017

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Leuven, 28 January 2017 Xenics, Europe’s leading developer and manufacturer of advanced infrared detectors, cameras and customized imaging solutions from the SWIR to the LWIR realm, comes to BiOS and Photonics West 2017 with a host of new developments. One of them being the new Tigris-640 cooled MWIR camera which will be demonstrated at their booth. This Stirling cooled midwave infrared camera is the successor of the Onca MWIR camera and is designed for high-end thermography and thermal imaging in R&D environments. In addition to theTigris-640, the company’s new (extended) SWIR camera, XEVA-2.5-320, will be demonstrated at the Xenics booth. Xenics exhibits in booths 8620 (BiOS) and 2237 (Photonics West) at the Moscone Center.

NEW COOLED MWIR CAMERA – TIGRIS-640

Xenics launches its new Tigris-640 MWIR camera series at BiOS and Photonics West. The Tigris series will replace the Onca MWIR cameras which are end-of-life. The Tigris-640 aims at applications where high speed, high thermal sensitivity, on-board thermography or broadband detectors are required.

The Tigris-640 is a cooled midwave infrared (MWIR) camera equipped with a state-of-the-art InSb or MCT detector with 640 x 512 pixels and pixel pitch of 15 µm. Both detectors are optionally available as BroadBand (BB) detectors, meaning that their spectral sensitivity is extended into the SWIR band. The Tigris-640 comes with a motorized filter wheel and is equipped with a variety of interface including GigE Vision, CameraLink, analog out, HD-SDI and a configurable trigger in- or output.

Main difference between the 2 available detectors, apart from the detector material, is their A to D conversion and their speed. The Tigris-640-MCT camera offers 14 bit images at a maximum full frame rate of 117 Hz. The Tigris-640-InSb comes with a digital detector that works in 13-, 14- or 15-bit mode at a maximum full frame rate of 250 Hz. Both frame rates can be increased by using a Window-Of- Interest (WOI).

Xenics Infrared Camera Distributor Singapore

EXTENDED SWIR INGAAS CAMERA UP TO 2.5ΜM

The new XEVA-2.5-320 is on display at BiOS and Photonics West 2017. The Xeva-2.5-320 is a SWIR camera designed for use in R&D applications like laser beam analysis and profiling, semiconductor inspection, hyperspectral imaging etc. where an extended SWIR range up to 2.5 µm is necessary.

The Xeva-2.5-320 SWIR camera is equipped with a Type 2 Super Lattice (T2SL) detector that is sensitive from 1.0 to 2.5 µm. It features a resolution of 320 x 256 pixels with a 30 µm pixel pitch. It outputs 14-bit data and is available in a 100 Hz or 350 Hz version. The Xeva-2.5-320 is equipped with a TE4 cooler. Together with its excellent thermos-mechanical design the operating temperature can be brought down to 203 K, guaranteeing low noise and dark current values, and resulting in excellent image quality. Other features include standard CameraLink or USB 2.0 interfaces, user-friendly Xeneth software, and an optional software development kit.

TO KNOW MORE ABOUT XENICS INFRARED CAMERA DISTRIBUTOR, SINGAPORE, CONTACT MVASIA INFOMATRIX PTE LTD AT +65 6329-6431 OR EMAIL US AT INFO@MVASIAONLINE.COM

Source – XENICS.COM

MV ASIA INFOMATRIX PTE LTD

3 Raffles Place, #07-01 Bharat Building,
Orchard Road
Singapore – 048617
Tel: +65 63296431
Fax: +65 63296432

E-mail: info@mvasiaonline.com / menzinfo@starhub.net.sg