Author Topic: az and alt angles  (Read 1441 times)

bovis

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az and alt angles
« on: April 22, 2011, 12:40:52 PM »
Hi Gabriel (and others),

I still have some difficulties to get the program working.

Is it correct that the az starting angle (when az = 0, noon) and the alt starting angle (mirror straight up) should both be set to +90 (if it is built correct of course) ?
When my motors rotate in the positive direction I have obtuse triangles. So my azimuth limit switch could be around +120 degrees and my altitude limit switch around +100 degrees.
Because in an earlier message I read that the limit switches should be placed in the 'morning' position (Sun west and low).
Is this correct ?
grtz

Boaz


 
 
« Last Edit: April 23, 2011, 01:03:09 AM by bovis »


bovis

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Re: az and alt angles
« Reply #1 on: April 24, 2011, 12:51:37 PM »
Nobody ? ???

the problem is now that my altitude rotation is far to much. I dubbelchecked all the settings but setting #9 and #11 I dont understand.

#9 should be 90 (if well build of course)
#11 in my case is -15, or should it be 105 ? (15 degrees from vertical)

grtz
Boaz
 


Gabriel

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Re: az and alt angles
« Reply #2 on: April 25, 2011, 02:02:17 PM »
Hey Bovis,

I'll try to see if I can help. The pictures you uploaded should make it easier for me to see how you have it set up. It looks like you have the right idea so far.

"Is it correct that the az starting angle (when az = 0, noon) and the alt starting angle (mirror straight up) should both be set to +90 (if it is built correct of course)?"
For your heliostat, it looks like using +90 is correct for both the altitude and azimuth starting angles.

"When my motors rotate in the positive direction I have obtuse triangles. So my azimuth limit switch could be around +120 degrees and my altitude limit switch around +100 degrees."

Whether or not the leadscrews form obtuse or acute angles doesn't have an affect on what angles you input for the altitude and azimuth limit switches. From the pictures, it looks to me like that azimuth limit switch should definitely have a negative value. Assuming the altitude limit switch is "underneath" the mirror, it should also have a negative value. In the picture it looks to me like the azimuth is somewhere around -50 degrees and the altitude is (maybe) somewhere around -15 degrees.

If your stepper motors are moving in the wrong direction, away from the limit switches, when the program is first reset, you can fix it in setting#6 and #13.


"Because in an earlier message I read that the limit switches should be placed in the 'morning' position (Sun west and low).
Is this correct ?"

Yes, that is correct.


Setting up a heliostat to work with leadscrews like you and I have might be relatively easy to build, but it can be extremely difficult to debug simply because there are some many variables to keep in order.

What might help is if you go to the tab named "Functions" in the Arduino Sun Tracking / Heliostat program and then find the function named "heliostatAngle3" located near the bottom of the page. There you should find the same code as what is below this text.
Once you have found it, remove the "//" comments so that the calculated altitude and azimuth will be displayed in the Serial Monitor. You can double check to see if your heliostat is moving to the calculated angles simply by measuring them.

  if (returnAltAz == 1){
    //Serial.println("machinealt");
    //Serial.println(machinealt);
    return machinealt;
  }
  if (returnAltAz == 2){
    //Serial.println("machineaz");
    //Serial.println(machineaz);
    return machineaz;
  } 

Hope that helps!
Also, sorry I wasn't able to reply sooner. It's been a busy week.