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Posted by Sherlock | Oct 08, 2014 @ 04:33 PM | 1,915 Views
(Edit : added new led setup pictures.)

Finally got some video though I still need to get a YouTube or Vimeo account.

The prototype is working great but I already have plans to improve on it. Mainly everything will be cleaned up and made more compact. I want to scale everything down and get rid of the extra wiring.

Version 2 improvements -

- I bought some small led's that will be mounted in the nose to be shaded from the sun while still visible from the camera.

- mount the angle sensing chip directly to the plastic bearing tube. This will make it very easy to place it properly near the magnet. I will put the magnet on first then attach the chip which will be mounted to some depron. I will make the whole bearing tube and AoA vane shaft smaller too. Should be much more compact.

- a smaller AoA vane. I think a much smaller one will work just fine and will be less likely to get damaged. I used a larger toothpick and I think a standard one will work. Eventually I might get one 3D printed.

- Smaller connectors for the led's. The servo connectors are squished in at an angle where they attach to the Arduino pins. Micro servo leads would solve this problem although I might end up just soldering them directly.

Here are the pictures of the new smaller led's. The light they give off is very directional. It is very bright seen head on and relatively dim from the sides. I will bevel the back side of the depron so that when mounted in the nose they will be pointing directly at the camera.
Posted by Sherlock | Oct 07, 2014 @ 09:53 PM | 1,270 Views
Software

So once I had all the hardware put together I needed to get the AoA range set up. To do this you need to know the values coming out of the chip. I wrote a simple program to read the value and display it on the computer screen using the Serial Monitor function in the Arduino programing environment. With the program running you click on Serial Monitor and a small window pops up that displays the output of the chip. Here is the program:

Quote:
/*
AoA indicator test Program
This sketch will allow me to read the output of a  magnatic angle sensing chip so that the output ran ge
can be determined for measuring the Angle of Attac k of an RC plane.
*/

int SensorOut = A2; // analog pin for AoA sensor output
int AoA; // variable to read the value from SensorOut

void setup(){
  Serial.begin(9600);
  pinMode (SensorOut, INPUT);
}

void loop()
{
  AoA = analogRead(SensorOut);
  Serial.println(AoA);
  delay(500);
  
}
So with this running I set the AoA vane to an approximate 0 AoA and noted the output. It was reading about 800 or so but it was very unstable. As I mentioned before it did not like the voltage from my PC power supply and after much frustration I hooked the chip up to power from the Arduino and it was perfect Now I got a good reading from 0 AoA to what I guessed was near stall angle. This range was about 800 to 900. I would fine tune this range after flight testing.

I had called Lou...Continue Reading
Posted by Sherlock | Oct 06, 2014 @ 10:57 PM | 1,914 Views
So I got the magnetic chip soldered on to the board. Next it was on to the LED set up. Nothing special here. I took a small piece of depron a quarter inch by about 4 inches and pressed the LED's through. The negative leads were soldered together and then a wire was run from the last one to ground on the Arduino. The positive leads all got 220ohm resistors and were individually soldered to 3 servo leads. These were then plugged into pins 2 through 9 on the Arduino on which I had soldered 90 degree pins.

The AoA wind vane was super simple to build. Its a toothpick with a balsa fin on the back and clay on the front to give it neutral balance. The vane was attached to a carbon rod that was riding in a plastic tube that just fit. The tricky part was getting the magnet on the other end of the carbon rod. The chip sits inside the cockpit on a small piece of depron positioned so it is almost touching the magnet. I needed to set the magnet at the proper location on the chip to get a good range of voltage output. The chip detects the north/south field of the magnet and is set so that 0 degrees is output with north on the top of the chip. The chip detects 360 degrees of motion and varies the voltage output based on the angle. It is unreliable from the 360 back to 0 portion so you want to make sure your 0 AoA to max AoA will not be near this range. The actual range used is quite smal (about 15 degrees) so as long as you are not near it you have plenty of space to work...Continue Reading
Posted by Sherlock | Oct 06, 2014 @ 04:54 PM | 1,879 Views
Finally found some time to get a build log started This setup uses a magnetic angle sensing chip, an Arduino micro controller and Led's to indicate the Angle of attack of my F-16. The led's will be on the nose of the F-16 visible from my FPV camera. There will be three green, three yellow and two red led's to indicate low, medium and high AoA respectively.

Original discussion thread here:

http://www.rcgroups.com/forums/showthread.php?t=2190654

Hardware:

Arduino Pro Mini


http://arduino.cc/en/Main/ArduinoBoardProMini

I chose the 16mhz 5 volt version. I think there should be no problem using the 8 mhz 3 volt version though. You will need to purchase some header pins to attach the programing lead to.

Pins:

https://www.sparkfun.com/products/553

programing lead USB to serial FTDI cable:

https://www.sparkfun.com/products/9718
You will need this to download your programs onto the Arduino.

This setup uses a magnetic angle sensing chip to send a variable voltage signal to the Arduino which then lights up led's according to the angle of attack. I found a few different manufactures on line and decided to go with one from a company called GMW due to its simplicity. I called the company with some questions and was transferred to their engineer who turned out to be a great guy named Lou. After telling him my plans he informed me that he had always wanted to try programing and had built R/C subs at one point. He always thought that the programing would be a little...Continue Reading