Doyle CFD is Developing a Real Time Shape Stripe Analysis System
Doyle CFD is developing a real time sail shape stripe analysis system. Analyzing the sail shape on the mini maxi Proteus is our first test case. Proteus has three in deck cameras (jib, port main, starboard main) connected to a high speed network and controlled by a mini computer running our real time shape stripe analysis code. Every five seconds images are taken and processed to calculate the shape stripe parameters such as twist, camber and location of maximum camber. A graphical user interface displays images from all three cameras with stripe data overlaid in real time so sail shape can be evaluated while sailing. The data from each image is saved for post processing where it is combined with the boats performance data.
The image above shows Proteus sailing in the foreground, with orange colored shape stripes on her sails. The shape stripes want to be a color that is easy to separate from the rest of the picture. We found bright orange works well, however other colors such as bright green can work as well. Below on the right is an image from the jib the camera and on the left is the same image after it has been processed. On the top of the processed image, the camber, twist and location of max camber are shown for each shape stripe. The LEb% field shows a measure of head stay sag calculated by fitting a curve to the leading edge of each shape stripe.
For real time viewing or post processing data from the boats, sensor information can be displayed along with the stripe information in a graphical user interface. Below is a screen shot of the GUI configured to show jib and main images and plots of boats speed, VMG and apparent wind speed. The red vertical line in the plots indicates the time of the image currently being displayed.