| Main Site areas:
Where can you go from here? |
Convertible Roof Deflection Measurement
for Jaguar Cars Ltd.
Prof. Peter J Bryanston-Cross & Dr Wanda Lewis
The OEL (Optical Engineering Laboratory) will develop a research team specifically to complete the measurements on the convertible roof. The team will evaluate several available measurement systems at the scale model stage.
Objective of the work.
Warwick University will use a camera system mounted on an antivibration mount which will be aerodynamically shaped and fitted to the body of the vehicle. The high resolution digital camera will use a ‘fisheye’ lens so that the complete whole surface can be viewed.. This system will map the surface over the whole surface area to an accuracy of deflection accuracy of 0.25mm.
Stage (1). Evaluation of the material and optical test system in the Warwick University wind tunnel. This work will result in a demonstration of the measurement technique on a ¼ scale model.
 | Size of model = 250mm |
| Measurement resolution required 0.2% stretch in the material under load. |
| Thus expected movement of the surface = 0.5mm over the whole surface, which translates to 50microns over an length of 25mm. |
If the imaging frame of the digital camera is 760 x 500 pixels and the distance between a pair of dots is taken to be 200 pixels, then the accuracy of the measurement can be made to .2% of 25mm which is 50microns.
Suggested pattern of operation.
A matt black roof, will have small 10pixel (1.2mmdiameter) sized dots painted on the on the surface with a spacing of 25mm. The objective is the use a single camera to measurement the deflection to an accuracy of 0.05mm in the ¼ scale model case.
A full scale model of approximately 1m2 would require an accuracy of 0.2mm measured over a grid of 100mm spacing.
The accuracy achieved by NASA for wing deflection measurement is 0.3mm over an area of 1m2.
Using sub pixel resolution it is possible to work to an accuracy of 0.25 pixel.
For a high resolution still camera a resolution of 2000 x 1000 can be achieved.
Demonstrate the curvature for a simple curved shape.
Demonstrate the measurement for a vibrating surface.
| OELWeb Features: |
| Undergraduate course notes can be found
here.
Download FRAN, our fringe analysis software that's free for non-commercial use. Ever heard an opera singer shake the house down? See what they are doing to themselves. Do you know how an internal combustion engine works? Find out here. |