Germany and the car share a long history. It was here, in 1886, that Carl Benz registered the patent for a petrol-powered vehicle with a four-stroke engine, the "Benz Patent-Motorcar Number 1". Today, brands such as VW, Porsche, Mercedes and BMW are famous the world over and represent the very best in quality and innovation. The automotive industry is the driving force of the German economy as well as the catalyst for many other business sectors.
Measuring technology is one such sector, where AICON 3D Systems GmbH is an established specialist. The company was founded in 1990 in Braunschweig, and develops, manufactures and markets optical camera-based 3D measurement systems. The company extended its product range to include high-precision 3D scanners following the takeover of Breuckmann GmbH in 2012.
Testing Wheel Behaviour
AICON 3D System GmbH has set a new standard in vehicle development thanks to WheelWatch, the optical measurement system. Before a car gets anywhere close to serial production, prototypes have already covered millions of kilometres during testing. As part of this process, careful testing examines exactly how wheels behave in the event of extreme manoeuvres. Just how do they handle bumps and wet roads? Do they remain stable when it comes to evasive manoeuvres or when travelling at high speed? Do the wheel wells still provide enough room even when tackling sharp bends? Here, parameters such as track, camber, suspension, steering angle and clearance are crucial.
Detecting Wheel Movement at 250 km/h
A high-speed camera from Mikrotron is the key component of WheelWatch. With a maximum speed of almost 500 frames per second, the EoSens® camera, equipped with a CMOS sensor, provides a resolution of 1280 x 1024 pixels. As a result, it takes sharp and detailed images, even at driving speeds of up to 250 km/h. The integrated high-performance flash also takes care of the extremely short exposure times required, which are in the microsecond range.
Tackling Tough Operating Conditions
The camera is exposed to extreme forces and has to be able to withstand accelerations, steering manoeuvres and abrupt braking. Furthermore, the camera must also function reliably during lengthy tests lasting several hours. Therefore, the engineers at AICON 3D Systems demand the very best in terms of sturdiness and long-term stability. "The camera operates reliably, despite sometimes facing tough operating conditions," confirms Robert Godding, Managing Director of AICON 3D Systems GmbH. "The camera coped very well with various challenging applications – not only in the field of wheel motion – and always delivers high-quality image data.”
Mounting the Measurement System on the Vehicle
One camera is attached per wheel, to enable it to fully capture the wheel and mudguard. Specially coded measurement targets are placed on the mudguard to identify the vehicle coordinate system. An adapter is mounted on the wheel, featuring a unique pattern of dots. The camera captures the wheel and simultaneously aligns itself with the surrounding mudguard. This means the camera does not have to be kept stable. Likewise, vibrations and bumps do not have any effect on the data measured. The system recalculates its position continuously to achieve the measuring data, thereby achieving maximum positional accuracy of approx. ± 0.1 mm and angular accuracy of approx. ± 0.015°.
Four cameras can be synchronised with each other, as well as with other measuring sensors. By way of example, movements in the engine block can also be detected using the EngineWatch system. Consequently, the system benefits from the compact size of the EoSens® camera. Measuring just 63 x 63 x 47 mm meant that it was possible for AICON 3D GmbH to develop a housing that fits into even the tightest of spaces.
Evaluating Images in the Camera
The measurement images are assessed right in the camera sensor using an FPGA image analysis processor and sent to the computer via a GigE interface, in real time. The results are available shortly after. Mr Godding considers the integrated FPGA technology to be one of the camera's best features. "Being able to use the FPGA built into the camera, for our own image processing purposes, was one of the reasons we opted for a Mikrotron camera. The collaboration required for this has gone really well."
The system is used on the test bench as well as during drives on the test track. However, it is also ideal for other movement analyses:
3D motion and position analysis
- Door slam testing
- Examining the opening and closing behaviour of doors, covers, windows
- Vibration analysis of components
- Robot rail measurement
- Machine control
3D deformation analysis
- Error analysis in the production line (e.g. welding processes)
- Component behaviour in wind tunnels or climatic chambers
- Collision analyses
- Material testing, structural analysis
6D positioning and alignment of individual points and rigid bodies