QMT Features: July 2013
The evolving game of measurement
What is the future of measurement and how can it fit with the changing manufacturing landscape? Jim Heley,  head of Integrated Manufacturing Group at  AMRC, looks at some upcoming technologies and trends.


Measurement is unarguably an important manufacturing process but it can often create a bottleneck that leads to delays, simply because parts cannot be measured fast enough using the traditional methods such as the CMM (coordinate measuring machine).  This leads to two logical solutions; either more of the current measurement systems are purchased and used in parallel to ensure the measurement times are in line with production times or; that new measurement techniques need to be developed with similar capabilities to the current methods but with the ability to make the required part qualifications faster. 

The current desire for digital manufacturing, where the ultimate aim is to control all production automatically and every aspect of the part can be linked back to the CAD model. Thereby creating a ‘digital thread’ right through to the final part which can be used to control or adapt all up stream processes. Changes made to the CAD data automatically flow through to production, quality, final assembly finishing etc.. CNC programs are automatically updated. This concept of a digital factory makes production far more consistent from planning right through to operations and creates a far more flexible and cost effective production capability, but it also further builds the case for inline rapid measurement and inspection methods so that measurement data can be made and fed back into the digital thread.

So what is the future of measurement and how can it fit with the changing manufacturing landscape? Further to this, what technologies are driving the current development trends?

The Advanced Manufacturing Research Centre, a part of the University of Sheffield, is interested in answering these questions. It’s Integrated Manufacturing Group is focused on the Digital Factory and the concept of fully integrating all processes including measurement and inspection onto the shop floor so that data can flow freely, be gathered automatically and used to enable intelligent decision making. The focus is on completing the digital thread from the design concept right through to the final product assembly. Getting this functionality in place would create much more efficient manufacturing processes.

A major area of focus according to the AMRC is media. The latest technologies that are emerging from the media industry are highly advanced and generally low cost because of the volumes or production. Motion sensing devices, extremely popular in the gaming industry, are a classic example of this. These technologies started (as far as gaming is concerned) in 2006, with the release of the Nintendo Wii. This platform has sold over 75 million units up until 2010 and brought the use of MEMS (microelectromechanical systems) clearly into the view of the general public and through hacks that are available, made their use simple and affordable.

The ‘Wiimote,’ the systems remote control unit, as it has been termed, uses MEMS to measure movement created by the user. It is not capable of measuring its location however, which limits its applications somewhat but, the system is excellent as a manual interface into the digital world. For example it can be used to control mechanical devices like robots, thereby eliminating the need for understanding the programming of such devices manually. Other applications are in maintenance or environmental control for example. MEMS sensors such as those used in the Wiimote can monitor the vibrations from a system (maybe a motor) and these can be used to predict failure or to monitor usage and shut systems down when they are not required.

Microsoft Kinect
Microsoft’s Kinect was brought out in 2010 as Microsoft’s answer to Nintendo’s Wii.  It consists of an infrared depth sensor, an RGB camera and a multi-array microphone. Microsoft have adopted an open attitude towards the system and have since released several SDK’s (software development kits) to allow users to develop and create their own specific software for totally customised applications. These range from bespoke media interaction control to novel healthcare and even defect location on motor vehicles. Industrial possibilities are numerous and often utilise the depth sensing capability of the system. The latest SDK to be released by Microsoft (Kinect Fusion) allows the system to be moved around to generate a point cloud of the area scanned.  This makes the Kinect effectively a £200 3D scanner that really opens the door to a whole host of applications in industrial scanning. Faro have recently released their Scenect software that uses the MS Kinect to generate 3D point clouds. 

The applications for the Kinect, ranging from simple measurement through to frame tracking and augmented reality are numerous and increasing daily due to the cost and open source nature of the device.

ASUS Xtion
The ASUS Xtion Live is another camera based platform that has similar capabilities to the Kinect. It too can be used with Faro’s Scenect software or other software to produce 3D point clouds.  This technology is now finding its way into manufacturing through devices like Fotonic’s P70 marketed as “Smart real vision – at low cost.”  This is a smart camera aimed at industrial applications and is based on the ASUS Xtion sensor.

LEAP
LEAP-Motion is bringing out a new sensor on May the 19th that utilises three infrared LED’s and a camera to track motion at a high resolution within a 1m x 1m x 0.5m area.  The system offers much better resolution (quoted at 0.01mm) than the MS Kinect or Xtion but over a much smaller working volume. However the cost is also less, with a release price of only $80 the LEAP offers great potential for modular development

Phones/mobile devices
The Microsoft Kinect utilises a depth sensor provided by Israeli company Primesense. The depth sensor uses infrared laser projection and a CMOS sensor to capture data, which creates a map of every ‘line of sight’ point and its position in space. The resolution of the depth map depends on the capabilities of the projector and sensor system.  Primesense are looking to apply this technology to mobile devices.  This will open up the market further with every smart phone out there becoming a potential metrology device capable of mapping and measuring its environment.

ProjectionWorks: optical projection
Other devices to come from the media industry are projectors.  For many years standard optical projectors have been used to deliver PowerPoint presentations or watch movies, but now they are finding their way into industrial applications.  A3L in the UK are supplying technology that allows an optical projector to be calibrated in 3D so that accurate assembly locations can be visualised on a part, without damaging or contaminating the part in anyway. Depending on the application, this can allow brackets to be located, masking to be placed prior to painting, fasteners installed in the correct hole, areas highlighted for inspection or an operation like adhesive application.

The system is providing benefit to the customer by optimising the assembly process through utilisation of the digital thread i.e. information from CAD. The system can be used with integrated intelligent tools like a torque wrench, so that nuts or bolts can be highlighted and the torque profile can then be recorded and wirelessly transmitted so that the data is stored against the correct nut for traceability or quality purposes.  All manner of tools can be integrated so that data can be recorded and stored against a location or position on the part making it ideal for gap and flush measurement, many types of gauging, torque, inspection, dimension measurement, roughness, hardness etc. One drawback of the system is the relatively low resolution of commercial projectors. This is improving although it is still some way behind digital camera technology.  Current high resolution specification in projectors is around 1920 x 1200 (NEC, PA500U) but newer systems in development are offering much higher definition solutions such as the Sony 4K projector (4096x2160 resolution) brought out for the home cinema market. 

The issue with these super high definition projectors is the brightness, which is only 2000 lumens compared to 5000 for the above mentioned NEC. Brightness is an issue because the image needs to be bright enough to overcome the ambient light.
This development is very exciting because it opens up further opportunities. A high specification structured light scanner like a GOM or Phase Vision system is essentially a high end projector and a camera.  As the resolution increases of cheap ‘off the shelf’ projectors, it won’t be long before they reach a level where they could be combined and used as a structured light scanning system allowing the reverse engineering of parts, their measurement and much, much more.

Clearly with the continued drive to improve media equipment performance, driven by demand and competition, and the low cost associated with its mass manufacture, it certainly won’t be long until we have highly accurate low cost digital systems integrated into our future factories.  The system offer capabilities ranging from monitoring equipment through to full 3D digitising. The applications of these systems will be wide and varied there is no doubt but it is looking more certain then ever they offer tremendous potential in terms of efficiency and cost reduction.l

Author Jim Heley email: j.heley@sheffield.ac.uk
  
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