DPRG mailing list archives: [DPRG] DPRG Spring 2008 Outdoor Robot Challenge: 10 May 08

Sat Mar 8 09:56:05 CST 2008

If atan gives you trouble, then use atan2(y,x), it uses the signs of  
both arguments to determine the quadrant of the return value.  atan2 
() should be available in most decent libm implementations.  avr-libc  
has it.  See:
http://www.nongnu.org/avr-libc/user-manual/ 
group__avr__math.html#g054230cd7e4c12958dbfac75ab6886e5

!!Dean

On Mar 8, 2008, at 09:11 , DeltaGraph at aol.com wrote:

> David,
> Thanks for the reminder.
>
> As for me, my reward for finishing a current project will be to  
> have some time to work on my outdoor robot. Thanks for all of your  
> posts. One, for me, I thought quite interesting is  that odometry  
> heading need not involve arctan function. I did my own derivation,  
> and felt quite proud about it -- but it relied on arctan. My  
> experience with that function has always gotten me into trouble  
> with signs.   sine and cosine much more friendly.
>
> I think I am going to set my sights on just #1 and #2, but It will  
> be fun to see how I can do with my favorite,
> in I expect, last minute "go for it" mode.
>
> Ron