Arduino Solar Tracker

Summer - Fall 2011

11-18-2011

Solar Tracker

I built a solar tracker like this one modified to use my Arduino. If you haven't seen any videos by ScienceOnline before, you're in for a real treat! Check out their website too http://hilaroad.com/ for some more great ideas and scientific knowledge.

This was my first real Arduino project and I think it went rather well. I learned a lot but now I really need to get out in the sun to do some real testing. I'd still like to use this to power some other projects and / or add some other features... so many empty pins on that RBBB board.

a few pics

parts & materials

RBBB board from Moderndivice.com - $13.00
x2 Monocrystalline Solar Cells ( 37 x 66mm ) from solarbotics.com - $8.25 ea
x2 Large Servos from - sparkfun.com - $12.95 ea
5V voltage regulator
x4 photocells
x2 10k Ω resistors
IN4004 rectifier diode from radioshack ( 276-1103 )
x4 rechargeable NiMH AA batteries 1,2V 1800mAh
battery holder
bread board
wood
metal bracket left over from ikea furniture
wire

schematic

initial code ( get the most recent code on github)


										#include <Servo.h>

										
										/*

										5V

										pin D9 = horizontal servo

										pin D10 = vertical

										pin A0 = horizontal photoresistor (white) 10k resistor in between

										pin A1 = vertical photoresistor (blue) 10k resistor in between

										*/

										
										//create servo objects to control servos

										Servo horizontalServo; //bottom - 0 points to x 

										Servo verticalServo; //top - 75 approx straight up, 180 seems too much, 170 max maybe


										int photoresistorHorizontal = 0;

										int photoresistorVertical = 1;

										

										int horizontalDegree;

										int verticalDegree;

										

										

										//smoothing

										const int numReadings = 10;

										

										int  Hreadings[numReadings]; // the readings from the analog input

										int  Hindex = 0;  // the index of the current reading

										int  Htotal = 0; // the running total

										int  Haverage = 0; // the average


										int  Vreadings[numReadings];

										int  Vindex = 0;

										int  Vtotal = 0;

										int  Vaverage = 0;

										

										void setup(){

											Serial.begin(9600);

											horizontalServo.attach(9); //bottom - horizontal

											verticalServo.attach(10); //top - vertical

											pinMode(photoresistorHorizontal, INPUT);

											pinMode(photoresistorVertical, INPUT);

											

											// initialize all the readings to 0: 

											for (int thisHReading = 0; thisHReading < numReadings; thisHReading++){

												Hreadings[thisHReading] = 0;

											}

											for (int thisVReading = 0; thisVReading < numReadings; thisVReading++){

												Vreadings[thisVReading] = 0;

											}

										}

										

										void  loop(){

											horizontalDegree = map(analogRead(photoresistorHorizontal),0,1023,0,179);

											horizontalDegree = 179 - horizontalDegree; //have to make opposite since soldering messup

											verticalDegree = map(analogRead(photoresistorVertical),0,1023,0,90); // 60 degrees max for vertical servo

											

											

											//average horizontal

											Htotal= Htotal - Hreadings[Hindex];

											Hreadings[Hindex] = horizontalDegree;

											Htotal= Htotal + Hreadings[Hindex];

											Hindex = Hindex + 1;

											if  (Hindex >= numReadings){

												Hindex = 0;

											}

											

											//average verticle

											Vtotal = Vtotal - Vreadings[Vindex];

											Vreadings[Vindex] = verticalDegree;

											Vtotal = Vtotal + Vreadings[Vindex];

											Vindex = Vindex + 1;

											

											if  (Vindex >= numReadings){

												Vindex = 0;

											}

											

											// calculate the average:

											Haverage = Htotal / numReadings;

											Vaverage = Vtotal / numReadings;

											

											

											horizontalServo.write(Haverage);

											verticalServo.write(Vaverage);

											

											delay(15);

										}

Follow up

Let me know if you have any suggestions or improvements email me