Here is the paddlewheel. Its a vacuform plastic housing with an acylic paddlewheel. The rod is the same carbon fiber that I used for the anemometer. I already have all the sensors working with the arduino so now all I have to do is put the pieces together. The question I've been wrestling with is: How do you average reading from the wind vane? Say you have 5 readings at varying degrees (from 0-360). For example; 10, 5, o, 355, 340. A simple average will be wrong because the readings wrap around a circle... Glen addressed this, but there are special cases that don't work in his solution. For instance when you have a reading like: 5,5,5,270,270.
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I got this situation in my own project. Here how I do it.
ReplyDeleteYou have to keep a double accounting : the existing one (0-360): 5,5,5,270,270 average: 111
and an alternate one (from -180 to +180): 5,5,5,-90,-90 average:-33
In the alternate list, find the min and the max:
min = -90, max = 5
Multiply min * max = minmax
minmax = -90 * 5 = -450
If minmax is positive : keep the original average (0 to 360) (not the case here)
If minmax is negative : we crossed either north or south
Calculate delta = max - min = 5 - (-90) = 95
If delta < 180 : we crossed north : take the average of -180to+180 and transform it to 0-360
Here we keep -33 which becomes 327 in 0-360
If delta > 180 : we crosses south: keep the original average (0-360) (not the case here).