Sunday, October 17, 2010

Wind Direction Finder: Nearing Completion




The wind direction indicator has seen a good deal of progress since my last post.  The vane and indicator cases have been finished and much of the programming completed.  The vane electronics and power supply are housed entirely within PVC pipe to prevent moisture from damaging the device and to allow easy mounting to the top of the mast.  The vane itself has been built from recycled parts: a pop-up sprinkler, panda express chopstick and beer can. I'm currently working on a way of securely mounting the PVC to the top of the mast where the vane will transmit from.  The vane is powered by two AA batteries which should supply the transmitter with 90+ hours of continuous operation; more than enough for a weekend of sailing.

The display electronics have all been placed in a waterproof pelican case.  They will be powered from an external 12v battery typically stowed in the hold of the boat.  This display device shows graphically and numerically the wind direction relative to the boat.  I have also incorporated a 5min and 1min countdown timer helpful in small boat sailing for timing the start of a race.  From the display, you can also turn off the vane transmitter to conserve battery power.  The vane will still require some power to listen for a "turn on" signal to resume broadcasting the vane direction.  Interfacing with the display electronics is done through a capacitive touch sensor mounted on the inside of the pelican case.  This keeps the electronics protected from water, even if the Kraken were to pull the boat under.

Wireless wind vane and display box with battery

7 comments:

Anonymous said...

Hey, very cool project! What is the type of that magnetic shaft encoder and from where did you get it? I'm dreaming of building a wind vane myself.

Best christmas wishes!

K.

Glenn Langton said...

Thanks for the comment! The encoder is a MA3 Miniature Absolute Magnetic Shaft Encoder, from US Digital. This link should take you to the page: http://usdigital.com/products/encoders/absolute/rotary/shaft/ma3/ You'll need to select the interface, torque, and shaft diameter to fit your needs. I chose the ball bearing option so the vane reacts to even the slightest breeze.

Cheers, Glenn

Anonymous said...

Thank You for the quick replay! :-)

K.

Greg said...

So how's this working for you? Any issues popup?
New to this, so I was wondering if you could post some more information.

Nice job by the way :)

Glenn Langton said...

Hi Greg,

Since building the project, I discovered I used the wrong trigonometric functions to average wind direction. I should be using the functions outlined here: http://rosettacode.org/wiki/Averages/Mean_angle As a result, my code produces direction errors when sailing dead into the wind. Also, the battery life and form factor are somewhat lacking. If I were to re-do the project, I would use Bluetooth and a smart phone/tablet. Contact me via e-mail though, and I can send you my code or answer any additional questions you might have!

Cheers, Glenn

Tobias Rådenholt said...

Could you please share your code for smoothing/averaging wind direction?

Glenn Langton said...

Hi Tobias,

As noted in the above comments, I discovered I used the wrong trigonometric functions to average wind direction. My code produces incorrect values when sailing dead into the wind. Let me know if you still wish to take a look and I'll send you an email with my code.

Cheers, Glenn

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