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IND53 LUMINAR

Publishable JRP Summary Report for JRP IND53 LUMINAR Large Volume Metrology in Industry Background Large Volume Metrology (LVM) – measurement of size, location, orientation and shape of large objects, machines, assemblies or installations - is critical in many high value industries where the EU is globally competitive, such as aerospace, automotive, civil engineering, and power generation. LVM is also used in critical periodic re-alignment of large advanced science facilities such as those at CERN or ESRF, or in industrial surveying industries. LVM is usually performed in situ, because the items being measured or aligned are too large to fit within conventional measuring machines or too bulky to transport. State of the art LVM systems, such as laser trackers; photogrammetry; indoor GPS are limited by technical issues, especially for users working in non-ideal environments such as large factories and aircraft hangers. Issues such as the effect of the environment on LVM tools as well as the item being measured (e.g. thermal distortion of large structures, refractive index effects on optical-based measuring systems), loss of traceability in absolute distance metrology, and inflexible measuring devices, are holding back industries which compete by being leading edge. This project will develop new measuring systems, deliver new knowledge and best practice that will enable measurements to be made faster, more flexibly and achieve better accuracy in typical industrial environments. Need for the project Environmental regulations e.g. Clean Sky Joint Technology Initiative, the EU Aviation Directive (2008/101/EC) demand reduced aircraft emissions and these are best achieved through manufacturing new aircraft designs (e.g. laminar flow wings), which depend on machining and assembly operations which are more accurate than currently achievable. To compete globally, automated EU ‘Smart Factories of the Future’ will require ubiquitous metrology e.g. for self-guided robots at sub-millimetre accuracy over the entire factory, but without installing expensive thermal environment controls. The Large Hadron Collider’s successor at CERN will require 20,000 sub-assemblies to be aligned to ~10 µm every 200 m – ten times better than currently available. High value engineering (e.g. large parts for airliners, ships, submarines, civil nuclear, wind energy) cannot afford €10k per item per day costs of waiting for thermal stability or slow LVM tools to complete complex measurement tasks on items ready for despatch. All the above needs require better large volume metrology (more accurate, faster, flexible, traceable), yet there are few research groups worldwide addressing these needs. This consortium brings together most of the leading researchers in this field to deliver new metrology tools and knowledge. Scientific and technical objectives The consortium is devoting resources to each of the following scientific and technical objectives:  Develop several new measuring tools and techniques that are capable of operation in typical industrial LVM environments, based on several different operating principles, to maximise the range of applications where they can be used, over volumes of 10 m × 10 m × 5 m to a target accuracy of 50 µm.  Develop new traceable absolute distance meters to operate over ranges of at least 20 metres, thereby ensuring on-going traceability is maintained.  Develop both line-of-sight refractive index measuring systems as well as a novel multi-sensor system that can measure refractive index effects over a 3D volume. These systems will enable on-line compensation of refractive index effects in industrial environments over volumes up to of 10 m × 10 m × 5 m with a target accuracy of 1 part in 107.  Undertake the necessary modelling to understand and predict how large multi-component structures (such as aircraft wing segments) behave in non-ideal measurement environments.  The capabilities of the developed new technologies, instruments and approaches will be verified and demonstrated using measurements at partner laboratories, and in real-world industrial environments.

Report Status: PU

Public

Publishable JRP Summary P1 of 4 Issued: December 2015

IND53 LUMINAR

Expected results and potential impact Develop several new measuring tools and techniques that are capable of operation in typical industrial LVM environments, based on several different operating principles, to maximise the range of applications where they can be used, over volumes of 10 m × 10 m × 5 m to a target accuracy of 50 µm. A new measuring tool based on the technique of divergent beam frequency scanning interferometry has been demonstrated for the first time at short range including the ability to measure the range to multiple targets simultaneously with in situ traceability to the SI via a gas cell frequency reference. The measuring range of the technique has been increased through the use of spatial light modulators which also allow beam shaping and steering. Improved signal processing and a novel dual-wavelength technique allow the system to compensate for the presence of vibration and a target identification and tracking camera system has now been integrated. Resolutions down to 0.1 µm can be achieved by fitting to the peaks in the FFT spectrum that is obtained. Additionally the field of view has been increased to that of a cone of at least 90° cone angle. A prototype unibody sensor head has been designed (which is more compact that the previous binocular design) and is being tested before it is duplicated to produce a four sensor system. This novel coordinate measuring system will supersede existing techniques (laser trackers, photogrammetry) in many application areas bringing faster speed, better accuracy and traceability and enable the use of LVM in new applications. A second novel technique has been developed for target tracking in non-ideal environments based on the concept of intersecting planes (‘InPlanT’). The technique separates the accurate linear distance scale of three orthogonal axes away from the harsh environment by using three rotating ‘pointers’, one per axis, which track a target. The three distance measurements may therefore be operated in locations that are more stable than the main working volume. So far, a laboratory prototype for a single axis has been developed and tested and a second version has been designed. Testing showed noise limits ranging from 1.5 µm/√Hz to 7 µm/√Hz over distances from 0.5 m to 7 m and target tracking ability has been demonstrated. The system can generate a coordinate plane to ±35 µm flatness with conicity error of 111 µrad and compensation for yaw and pitch errors to 97 µm. This system is designed for operation in harsh environments. Develop new traceable absolute distance meters to operate over ranges of at least 20 metres, thereby ensuring on-going traceability is maintained. Develop both line-of-sight refractive index measuring systems as well as a novel multi-sensor system that can measure refractive index effects over a 3D volume. These systems will enable on-line compensation of refractive index effects in industrial environments over volumes up to of 10 m × 10 m × 5 m with a target accuracy of 1 part in 107. Work which addresses these two objectives simultaneously has progressed to the point where two different approaches are able to measure absolute distance – one technique is based on radio frequency modulation of a laser carrier signal and the other on phase measurements at multiple wavelengths. Furthermore the laser and interferometer optics of the phase-based technique have been miniaturised and the interferometer optics have been successfully incorporated into a tracking mechanism. The resulting device can track a moving target and provide absolute distance measurement even with beam breaks. The traceability to the SI comes from the incorporation of an iodine cell. In the RF-based device, a quartz oscillator provides the frequency traceability. The first device has achieved 1 part in 107 accuracy over longer ranges with 20 µm (length independent) accuracy at short ranges. The second device has been tested at ranges up to 3 m: the telemeter at 1550 nm provides good results (13 µm standard deviation) – this is currently limited by the reproducibility of the mechanical zero, but improvements are in progress. The telemeter at 773 nm presents a worse resolution and accuracy (42 µm), which is limited by the optical interferences (laser output is of high coherence). Initial tests of compensation for refractive index using both devices are promising - a low accuracy independent measurement of humidity is required for both systems, but this is easy to achieve in typical environments. The phase-based device has been demonstrated over a 20 m range and both devices are being prepared for on–site testing at the GUM 50 m tape bench and live measurements at Airbus UK. Both devices can measure within volumes at least as big as specified in the objective and one can measure over much longer ranges. Additional work has been progressing based on using a photogrammetric approach to 3D refractive index monitoring and this is now detecting dispersion signals using a mixture of different hardware approaches. These include the use of active targets operating across the visible spectrum and the use of a digital axicon camera system. Testing of the technique has taken place at NPL and at GUM over the temperature range 17 °C to 30 °C and further testing is planned in the near future in preparation for the on-site work at Airbus. Beam bending effects in excess of those predicted by theory had been observed and traced to thermal distortion of the camera/lens system. The volumetric bundle adjustment software has been

Publishable JRP Summary

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Issued: December 2015

IND53 LUMINAR

updated and the data from the digital Centrax camera is now being used together with the images from the other camera systems as well as using multiple-wavelength light sources. Radial distortions from the camera lenses ranged from 0.1 µm to 145 µm and from the cameras 1.1 arc second to 2.7 arc seconds (with the digital Centrax being limited by the current CMOS sensor). RMS agreement with 3D control points on a reference model was of the order of 0.5 µm. Dual 150 mm cameras are being prepared with co-axial IR/violet quadrature targets for mutual pointing through a thermocouple corridor to give a set of sight lines with known thermal gradients for the testing at Airbus. They will provide detection of environmental stability and long term drift over a ~30 m x ~0.25 x ~0.25 m volume. Undertake the necessary modelling to understand and predict how large multi-component structures (such as aircraft wing segments) behave in non-ideal measurement environments. Basic tests have been performed on mapping FEA results with those from experiments on simple objects. This has led to better understanding of the effects of FEA mesh size on accuracy of model outputs and on optimising thermal sensor position. A report has been prepared on a survey of wireless temperature sensing systems (often used in LVM applications) and a design of a test assembly artefact (simulating typical multi-components structures) has been completed and the item has been manufactured and used to demonstrate compensated measurements which have achieved an accuracy better than that previously possible using simple linear models over a raised temperature range similar to that encountered in industrial environments. The capabilities of the developed new technologies, instruments and approaches will be verified and demonstrated using measurements at partner laboratories, and in real-world industrial environments. Final testing of the new hardware devices will take place at the GUM 50 m tape bench, on-site at Airbus, at the AMRC in Sheffield (UK) and at the PTB tracker wall. PTB have been using their laser Tracer system to re-calibrate their tracker wall and GUM have updated their 50 m bench with new air conditioning and heating systems (to simulate non-ideal environments) and developing a femtosecond comb-based absolute distance meter, whilst installing backup sensors for air temperature, pressure and humidity. The results from the on-site tests will be presented at the end of project workshop which will be at NPL on 18-19 May 2016. The workshop will also include presentations from end users and will be used to identify new and unsolved challenges in need of future research. Separately, and in addition to the original project aims, REG(KIT) has completed their work on studying spatiotemporal variations of kinematics in robots and laser trackers. Their work has focused on developing a kinematic analysis method incorporating additional information about the kinematic process and on preparing a description of kinematic characteristics of glass reflectors often used in dynamic applications. As a test, they joined forces with PTB to undertake simultaneous measurements of an industrial robot using their laser tracker and an independent high accuracy measurement system comprising four laser Tracers working with PTB’s multilateration software. Comparison of the laser tracker data with the more accurate 3D data from the multilateration system has shown interesting behaviour which has since been resolved by a fundamental change in the analysis approach. This change (the use of Eigen mode spectral analysis) may be critical for other large volume measurement systems to prevent mathematical fitting routines from choosing the wrong solution (i.e. a solution that is mathematically ‘correct’ but not optimum from the physical viewpoint). Accurate control of robotic systems in factories (required for advanced manufacturing) will benefit from this work. The first direct results of the project will be the new measuring devices and knowledge as described above, including their demonstration in a ‘live’ end-user environment. The devices will be available for immediate use and the technology and IP that underpins them will be ready for licensing to third parties. In fact, two metrology companies are already in negotiations with project partners regarding collaborative work or licencing of the IP and the work preparing for and delivering the project has resulted in 5 patent applications. The knowledge generated through using the new devices will be immediately available for consortium members and wider industrial audience via an end of project workshop, and various publication/publicity (reviewed journals, trade magazines, conference presentations, standards committees, future metrology research strategy). The outputs are already appearing in a range of peer-reviewed journals and in 17 conference papers and posters (for some published examples, see the project website – address is below). Project members have also been invited to give presentations on their progress to potential end users (CERN, Boeing, Diamond Light Source, Airbus, BMW, and Jaguar Land Rover). Further impact will be through the uptake of these new devices by the end users: Compensation for refractive index and turbulence effects will allow aerospace (€94.5 billion turnover) to reduce measurement uncertainties, thereby allowing more accurate alignment, machining and assembly, or

Publishable JRP Summary

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Issued: December 2015

IND53 LUMINAR

to reduce waiting time for air stability. This will lead to reduced machining waste material, better conformance with tolerances, less re-work and reduced setup times (29,000 new aircraft, €2.3 trillion value, required by 2030, with 20 % reduction in lead time). Aircraft will contain less dead-weight due to reduced shimming and step-gap filling, leading to better fuel efficiency and lower emissions (1 kg of weight loss saves 10 tonnes of fuel a year per aircraft1 and each tonne of fuel saved reduces CO 2 outputs by 3.15 tonnes)2. This helps address several EU Directives concerning aviation, noise at airports. Similarly, future factory-wide metrology networks will benefit allowing progress towards the vision of the ‘future factory’ (mechanical engineering: 3.25 million people in Europe, €498 billion turnover including automotive at 2 million people: €140 billion). Advanced thermal compensation will enable end-users, particularly those in large aerospace or marine manufacture and assembly to demonstrate conformance to tolerance without expensive and energyintensive thermal control of large environments such as aircraft hangars. This allows manufacturers to work on next generation aircraft such as laminar wing concepts without additional energy costs in production (typically a million kWh per year air conditioning energy saving). Demonstration of new traceable ADM technologies will allow the next generation of commercial laser trackers and other optical measuring devices to achieve intrinsic traceability to the SI, with sufficient accuracy to abandon the IFM systems, whilst retaining user confidence. The line-of-sight refractive index systems and ADM systems can be coupled to provide refractive index compensated reference lengths for other existing and future measuring systems, e.g. photogrammetry networks, which can be used on larger structures such as long wind turbine blades (100 m are now contemplated) The ADM-based refractive index compensated tracking laser interferometer will supplant existing devices for use in industrial environments. The novel InPlanT technology will demonstrate a possible approach for tackling harsh environments (e.g. civil nuclear: £600 billion for new nuclear build, and £250 billion for decommissioning in the UK alone). The novel multi-target measuring system based from NPL will offer a flexible, fast, accurate multi-path measuring system. This will be ideal for mapping and monitoring deformation of large machine tools (the EU is the world’s biggest exporter of machine tools). The line-of-sight refractive index systems and ADM systems can be coupled to provide refractive index compensated reference lengths for other measuring systems, e.g. photogrammetry networks. These would help solve problems in large science (CERN, ESRF) facilities where performance of existing LVM tools is insufficient for next generation accelerators. In proton therapy, beams of protons are directed at a tumour and penetrate the tissue with minimal lateral scattering - much better than with X-rays – improved LVM will reduce the setup and maintenance costs of such facilities and increase their throughput by better alignment of the beam delivery systems. JRP start date and duration: JRP-Coordinator: Dr Andrew Lewis, NPL JRP website address:

1 June 2013 (36 months) Tel: +44 20 8943 6074 www.emrp-luminar.eu

E-mail:[email protected]

JRP-Partners: JRP-Partner 1 NPL, United Kingdom JRP-Partner 2 CNAM, France JRP-Partner 3 INRIM, Italy JRP-Partner 4 GUM, Poland JRP-Partner 5 PTB, Germany

JRP-Partner 6 AIRBUS, United Kingdom JRP-Partner 7 SIOS, Germany JRP-Partner 8 USheff, United Kingdom JRP-Partner 9 UBATH, United Kingdom JRP-Partner 10 UCL, United Kingdom

REG1-Researcher (associated Home Organisation):

Glen Mullineux UBATH, United Kingdom

REG2-Researcher (associated Home Organisation):

Stuart Robson UCL, United Kingdom

REG3-Researcher (associated Home Organisation):

Thomas Ulrich KIT, Germany

The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union

1

http://www.lufthansagroup.com/fileadmin/downloads/en/LH-fuel-efficiency-0612.pdf Beginner’s guide to aviation efficiency, Air Transport Action Group (2010), http://www.atag.org/component/downloads/downloads/59.html 2

Publishable JRP Summary

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Issued: December 2015