des services à votre mesure +

Live Metrology Drives Large Scale Assembly

[ 29.09.2020 ]

Large scale metrology is a huge application field with ongoing continuous improvements. In the last decade, a lot of new high technologies have been introduced allowing industry to push away more of the technical boundaries and democratizing the field. We have now instruments capable of scanning millions of points per second with microns of accuracy, we have live tracking capabilities, and we have a vast array of software to drive and analyze data along with the engineers and experts to develop complex large scale metrology solutions.

3D Metrology Integration

In manufacturing industries, metrology is still often placed at the end of the manufacturing process to verify the quality of the produced parts, scraping parts and assemblies if nonconformities are found. Québec, Canada based Amrikart mindset is to integrate 3D metrology directly within the manufacturing process, so that 3D metrology drives the manufacturing process instead of only verifying the products. For this purpose, Amrikart’s experts develop automated applications to help large scale product manufacturers to produce faster, and always good parts. Driving the manufacturing implied being able to control the location of part assemblies within their required tolerances. Doing so with live tracking application allows a considerable time gain. With live tracking, it is possible to control whole alignment and inspection processes, gaining time, quality, and repeatability.

Large Scale Measurements and Tracking Challenges

When talking about large scale measurements and live tracking, experts in the field often think about Laser Trackers. Laser Trackers are great, they can track a target over large fields of view with a good accuracy. However, one of their disadvantages is they can live track only one target at a time, or for some brands, only one 6DoF artefact. Other instruments, such as 3D camera (Hexagon MoveInspect, Creaform C-Track, GOM Aramis, etc.) can live track several targets or 6DoF artefacts, but in a limited field of view. So, to track in live several 6DoF frames within a large field of view (at least 20 x 20 meters), you need either a lot of trackers, or a lot of 3D cameras. And all of them would need to be permanently synchronised and accurately located to each other in a same global coordinate system to always control their global location, leading to expensive solutions. The lines of sight are a challenge too. All the actual metrology solutions need a straight line of sight for measurement. But, in many industries, lines of sight are often blocked by manufacturing operations, structures, tooling, workers, etc. This is a huge challenge for automated measurements, and Amrikart teams have worked on solutions.

Combining Instruments from Different Manufacturer – The Best from Each

Amrikart’ automation experts are resolving the large-scale challenges by combining different technologies together to overpass the individual equipment weaknesses and create a solution that provides only the strengths of the implied technologies. One of its developed solutions combines the 7D Kinematics iGPS with a Hexagon MoveInspect mounted on a wheeled cart.

The iGPS is a unique large-scale metrology technology allowing to live track targets on very large volumes with a uniform accuracy up to 0.015’’ (0.38 mm). iGPS is composed of satellites emitting laser rays and receptors (targets) receiving these rays. By triangulation of the laser signals from at least 3 satellites (similar to a car GPS system), the 3D location of all the receptors can be determined and live tracked. iGPS can track independent targets and 6DoF frames over the whole covered volume – satellites have a 30 meters range, adding satellites to the network expands the measurement volume , and all are permanently linked within the same global coordinate system. iGPS receptors still need a line of sight from at least 3 satellites, but by adding satellites in the workspace, and optimizing their distribution, users can obtain a robust network where manufacturing operations do not disturb the measurements. With the iGPS technology, the shop floor becomes a complete metrology cell where you can live track independently a lot of targets and 6DoF frames used in different applications and working stations. This is real advantages in final assembly lines of large structures such as trains, planes, satellites, ships, bridges, etc. to align all the subassemblies altogether.

iGPS Receptors mounted directly on Hexagon MoveInspect

Amrikart engineers combined a MoveInspect 3D camera with the iGPS technology and designed and manufactured a frame with iGPS receptors mounted directly on the MoveInspect, so the MoveInspect itself is now accurately located in the measurement cell. The MoveInspect can measure its own data within its field of view, and this data is in the MoveInspect coordinate system. As the MoveInspect is permanently tracked in the measurement cell through iGPS, the MoveInspect measurements are easily located in the measurement cell by simple matrix transformations. MoveInspect can be moved all around the measurement cell as iGPS will always track it and measure its location accurately. With this type of connectivity it’s possible to develop a huge variety of applications.

Amrikart recently presented a project where a bracket was aligned to an aircraft wing with a collaborative robot. The collaborative robot effector being tracked by the MoveInspect 3D camera while the wing has direct iGPS sensors on it to locate its position. Amrikart were able to align the bracket on the wing within ±0.020’’ (0 5 mm) (2σ) of the targeted location with the advantage of being able to overpass the problems of the line of sight and global location. To align a bracket inside the wing, the MoveInspect is placed in front of the wingbox looking inside the wing skins to locate the bracket accurately compared to any other elements in the measurement cell. As the MoveInspect and robots are mounted on two wheeled carts, operators can easily move them all around the measurement cell, without thinking about how to relocate them as they are always located by the live tracking of the iGPS system.

How is it Technically Achieved?

Each instrument has its own software and SDK (software development kit) provided by the manufacturer. Most instruments can also be directly used with metrology software. However, few software’s allow to plug several instruments and connect them together in a live tracking application, add robots and actuators programming, add sensors and other I/O demands. Moreover, automation often involves the development of user-friendly custom interfaces since managers do not want their operators to be experts in complex software. These requirements, with the specificities of each instrument manufacturer, often lead to a considerable amount of programming and development, rising the costs to automate solutions integrated to the production process.

Amrikart has developed a software platform, name ProjectX2, to be able to link any instruments, sensors, actuators, robot, and analysis software together. This platform goal is to allow an easy integration of all the systems, custom interfaces creation, and centralized programming for a propagation in all the implied software, without the need to be expert in all of the software and instrument SDK’s. The ProjectX2 platform has been used to combine the iGPS technology with the MoveInspect 3D camera and a collaborative robot.

Going Further

With the iGPS system, it is possible to locate and live track any type of frames within a large-scale area. Frames can directly be produced parts or subassemblies but can also be any other measurement instrument or device – 3D scanner, cameras, Laser Trackers, Laser Radars, Scanstations, sensors, robots, actuators, cranes, structures, etc.. All the instruments are located and live tracked within a global coordinate system in a measurement cell than can always grow by adding new satellites, so all the data are located within the same global coordinate system, in live. This allows a total control of manufacturing processes, and the automation of whole measurement and alignment processes with very good accuracy, reliability, and provides faster operations.

Article écrit par Jérémy Arpin-Pont, publié sur Metrology news