imaging and machine vision europe june/july 2010 www.imveurope.com


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news


Ariane 5 rocket welded with laser vision system


An automated welding system employing structured lighting and machine vision has been used to weld the upper stage nozzle of the Ariane 5 rocket, which made its 50th flight from the Kourou spaceport in French Guiana on 21 May. Supplied by Oxfordshire manufacturer, Meta Vision Systems, the laser-based tracking system, Meta Scout, is able to detect and follow a joint even when there is no discernable gap or step. Before welding, the nozzle profile


is created by bundling the tubes together and spiral winding them around a copper-coated aluminium mandrel. During a majority of the welding process, which does not use any filler material and therefore does not add weight to the nozzle, the Meta-Scout is able to resolve the seam between adjacent tubes and follow it conventionally. However, the square profile of the tubes near


the engine end is flattened to achieve the correct fit, with the result that there is no visible feature to track. It is here that the sensor uses its novel ‘zero gap’ functionality to direct the robotically-deployed torch to weld the joints. Five laser lines projected onto the workpiece surface allow measurements in six degrees of freedom, three orthogonal and three rotational.


news from UKIVA By Don Braggins


Vision technology has taken immense strides since the first emergence of the term ‘machine vision’ in the 1980s and is now a fully-established industry in its own right. Recently, however, there have been indicators that suggest vision is becoming a commodity in manufacturing. For example, at the Vision Technology Exhibition (VTX), in Birmingham in April, exhibitors were distributed throughout the hall rather than being concentrated in a single area, as in previous years. A number of UKIVA members exhibited at VTX and the consensus was that there was a clear switch of interest from visitors to the show – away from pure vision and towards the use of vision to solve manufacturing problems. Many exhibitors (23 by my


count, excluding existing UKIVA members) featured vision as elements in their various systems at the Total Processing and Packaging Show, which finished on the day of writing this article. The Total Show also hosted a dedicated ‘Vision and Robotics Pavilion’. The combination of robotics and image processing enables the fault- free, fast, reliable and economic manufacture and quality assurance of all kinds of products in many areas. This is essential in helping UK manufacturing to be competitive in world markets. The uncertainty surrounding the political direction of the UK around the general election resulted in a significant weakening of the UK currency, making exporting easier. However, if the new government is seen to


be making a good start to its deficit reduction plans, the pound is likely to strengthen, making it even more essential to keep costs down. We have to accept that UK labour costs are significantly higher than in many other parts of the world, so automation is obviously key. UKIVA members attending the VTX exhibition all reported an upturn in enquiry levels and actual business since the beginning of 2010. This is in line with the findings from the latest machine vision market study from the Automated Imaging Association. The study, concentrating primarily on North America, concludes that vision sales could increase by 2.6 per cent in 2010, depending on the extent of the economic recovery and the rate of change in industrial production.


A structured light technique together with grey level vision analysis determines seam position, height and orientation with respect to the tool, despite the absence of a physical feature. The only provisos are that the material either side of the gap must have similar machined finishes and the sensor has to be positioned at close to 90° to the surface.


Vision aids earthquake research


A research project conducted by Eucentre (European Centre for Training and Research in Earthquake Engineering), based in Pavia, Italy, is currently using a vision-based analysis system to assess the level of structural damage in test buildings subjected to earthquake simulations. The aim of the project, funded by the Italian Civil Protection Department and Foundation Cariplo, is to determine how stable existing buildings are during and after an earthquake. The findings from the project will be used to verify the efficiency of the rules for seismic assessment and repair for existing buildings included in the Italian Technical Regulations for Construction (2008).


The research team, headed by Professor Alberto Pavese, developed the vision system using high-resolution cameras from Dalsa (2,352 x 1,728 resolution with a frame rate up to 120fps), supplied through the company’s distributor in Italy, Image S. A scaled 1:2 multi-storey building representing 50s or 60s construction was built on a shake table to simulate the conditions of an earthquake. Infrared reflectors were placed on the walls of the building in a set pattern, with the cameras recording their motion to analyse the displacement of the structure.


‘The system was used to gather information from the structure that can provide an idea of the level of damage before and after an earthquake,’ explained Pavese. ‘From the data, decisions can be made on whether the structure is repairable or whether it would have to be demolished.’


The first phase of the project is complete and the researchers at Eucentre are currently optimising the machine vision system to acquire further data.


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