1: English is not my firts language, sorry if i made mistakes trying to describe this project.
I made an autopilot for my RC helicopter (Sabre, i bought it in Hobbie People USA) with acelerometers extracted from the NunChuck of nintendo Wii. Now i just a beta, i will change the Arduino Decimila for the mini version, you know, for weight reasons.
Arduino just control the Axis X and Y of the helicopter, but i able to read signals coming from my RC, an order to arduino to move my helicopter, easy and smoothly in that axis (X & Y), i only have to control the rotation and altitude, the rotation is not a big deal because the heli is stabilized by build-in "Gyros". I recycled the joystick axis of NunChuck, to adjust the servos with out touching the code. To se more pictures enter here jordii07 | Flickr
The code:
#include <Wire.h>
#include <string.h>
#include <stdio.h>
uint8_t outbuf[6]; // array to store arduino output
int cnt = 0;
int ledPin = 13;
int voltPin = 2;
int apX = 0;
int apY = 0;
int minWii = 330;
int maxWii = 694;
/////////////////
int axisX = 0; //Acelerometer axis X
int axisY = 0; //Acelerometer axis Y
int axisZ = 0; //Acelerometer axis Z
int adjustX = 127; // adjust axis X
int adjustY = 127; // adjust axis X
int contador = 0; //Contador del ciclo FOR
////////////////////Read RC
int xPin = 7; //Pin IN of servo Axis X
int yPin = 8; //Pin IN of servo Axis Y
int timeX = 0; //Show the readed control position
int timeY = 0;
long lastPulseX = 0; // the time in milliseconds of the last pulse
long lastPulseY = 0;
long mstime = 0; // reads the time in miliseconds
long hptime = 0; // Reads the time in Microseconds
///////////////////Write Servos
int minPulse = 800; // Minimum servo position
int maxPulse = 2200; // Maximum servo position
int refreshTime = 20; // the time needed in between pulses
int servoXPin = 2;
int servoYPin = 4;
long lastPulseWriteX = 0; // the time in milliseconds of the last pulse
long lastPulseWriteY = 0; // the time in milliseconds of the last pulse
int pulseX = 0; // Amount to pulse the servo X
int pulseY = 0;
////////////////////////////////////
extern volatile unsigned long timer0_overflow_count; // Sistema de conteo en microsegundos
unsigned long hpticks (void)
{
return (timer0_overflow_count << 8) + TCNT0;
}
///////////////////////////////////
void setup ()
{
pinMode(servoXPin, OUTPUT); // Set servo pin as an output pin
pinMode(servoYPin, OUTPUT); // Set servo pin as an output pin
pinMode(xPin, INPUT); //The R/C signal pin as an input pin
pinMode(yPin, INPUT);
pulseX = minPulse; // Set the motor position value to the minimum
pulseY = minPulse; // Set the motor position value to the minimum
beginSerial (38400);
Serial.print ("Finished setup\n");
Wire.begin (); // join i2c bus with address 0x52
nunchuck_init (); // send the initilization handshake
}
void loop ()
{
Wire.requestFrom (0x52, 6); // request data from nunchuck
while (Wire.available ())
{
outbuf[cnt] = nunchuk_decode_byte (Wire.receive ()); // receive byte as an integer
digitalWrite (ledPin, HIGH); // sets the LED on
cnt++;
}
// If we recieved the 6 bytes, then go print them
if (cnt >= 5)
{
print ();
AutoPilot();
updateServo();
Serial.print ("\r\n");
}
cnt = 0;
send_zero (); // send the request for next bytes
delay(5);
}
void AutoPilot()
{
pulseX =((((axisX - minWii) * ((maxPulse-minPulse)/(maxWii-minWii))))+minPulse)-127;
pulseY =((((axisY - minWii) * ((maxPulse-minPulse)/(maxWii-minWii))))+minPulse)-127;
pulseX = pulseX + adjustX;
pulseY = pulseY + adjustY;
pulseY = maxPulse - (pulseY - minPulse);
if(axisZ <= 754)//just a test
{
if(axisX <= 500)
{
pulseX = pulseX - 300;
}
if(axisX >= 560)
{
pulseX = pulseX + 300;
}
}
Serial.print ("SrvX");
Serial.print (pulseX);
Serial.print ("\t");
Serial.print ("SrvY");
Serial.print (pulseY);
Serial.print ("\t");
}
void RadioControl()
{
/////////////////////////
if(millis() - lastPulseX >= 200) //Read Axis X every 5 milis
{
while(!digitalRead(xPin) == HIGH) //Waits for signal coming from axis X
{
continue;
}
mstime = millis();
hptime = hpticks()*4; //When the signal arrives, here we going to record the start time of reciving
while(!digitalRead(xPin) == LOW){
continue;
}
mstime = millis();
timeX = (hpticks()*4) - hptime; //Here takes the diferences of the Start and finish times, the result is the signal from RC.
hptime = 0;
Serial.print ("CtrX");
Serial.print (timeX);
Serial.print ("\t");
lastPulseX = millis();
}
///////////////////////////The same, but now for axis Y
if(millis() - lastPulseY >= 200)
{
while(!digitalRead(yPin) == HIGH){
continue;
}
mstime = millis();
hptime = hpticks()*4;
while(!digitalRead(yPin) == LOW){
continue;
}
mstime = millis();
timeY = (hpticks()*4) - hptime;
Serial.print ("CtrY");
Serial.print (timeY);
Serial.print ("\t");
hptime = 0;
lastPulseY = millis();
}
}
//Continue
void updateServo(){
if (millis() - lastPulseWriteX >= refreshTime) {
digitalWrite(servoXPin, HIGH); // Turn the motor on
delayMicroseconds(pulseX); // Length of the pulse sets the motor position
digitalWrite(servoXPin, LOW); // Turn the motor off
lastPulseWriteX = millis(); // save the time of the last pulse
}
if (millis() - lastPulseWriteY >= refreshTime) {
digitalWrite(servoYPin, HIGH); // Turn the motor on
delayMicroseconds(pulseY); // Length of the pulse sets the motor position
digitalWrite(servoYPin, LOW); // Turn the motor off
lastPulseWriteY = millis(); // save the time of the last pulse
}
}
// Print the input data we have recieved
// accel data is 10 bits long
// so we read 8 bits, then we have to add
// on the last 2 bits. That is why I
// multiply them by 2 * 2
void print ()
{
int joy_x_axis = outbuf[0];
int joy_y_axis = outbuf[1];
int accel_x_axis = outbuf[2] * 2 * 2;
int accel_y_axis = outbuf[3] * 2 * 2;
int accel_z_axis = outbuf[4] * 2 * 2;
int z_button = 0;
int c_button = 0;
// byte outbuf[5] contains bits for z and c buttons
// it also contains the least significant bits for the accelerometer data
// so we have to check each bit of byte outbuf[5]
if ((outbuf[5] >> 0) & 1)
{
z_button = 1;
}
if ((outbuf[5] >> 1) & 1)
{
c_button = 1;
}
if ((outbuf[5] >> 2) & 1)
{
accel_x_axis += 2;
}
if ((outbuf[5] >> 3) & 1)
{
accel_x_axis += 1;
}
if ((outbuf[5] >> 4) & 1)
{
accel_y_axis += 2;
}
if ((outbuf[5] >> 5) & 1)
{
accel_y_axis += 1;
}
if ((outbuf[5] >> 6) & 1)
{
accel_z_axis += 2;
}
if ((outbuf[5] >> 7) & 1)
{
accel_z_axis += 1;
}
axisX = accel_x_axis;
axisY = accel_y_axis;
axisZ = accel_z_axis;
adjustX = joy_x_axis;
adjustY = joy_y_axis;
Serial.print ("JoyX");
Serial.print (joy_x_axis, DEC);
Serial.print ("\t");
Serial.print ("JoyY");
Serial.print (joy_y_axis, DEC);
Serial.print ("\t");
Serial.print ("AclX");
Serial.print (accel_x_axis, DEC);
Serial.print ("\t");
Serial.print ("AclY");
Serial.print (accel_y_axis, DEC);
Serial.print ("\t");
Serial.print ("AclZ");
Serial.print (accel_z_axis, DEC);
Serial.print ("\t");
Serial.print ("btnZ");
Serial.print (z_button, DEC);
Serial.print ("\t");
Serial.print ("btnC");
Serial.print (c_button, DEC);
Serial.print ("\t");
}
// Encode data to format that most wiimote drivers except
// only needed if you use one of the regular wiimote drivers
char
nunchuk_decode_byte (char x)
{
x = (x ^ 0x17) + 0x17;
return x;
}
void nunchuck_init ()
{
Wire.beginTransmission (0x52); // transmit to device 0x52
Wire.send (0x40); // sends memory address
Wire.send (0x00); // sends sent a zero.
Wire.endTransmission (); // stop transmitting
}
void send_zero ()
{
Wire.beginTransmission (0x52); // transmit to device 0x52
Wire.send (0x00); // sends one byte
Wire.endTransmission (); // stop transmitting
}
//Remember i just a BETA, letter ill upload video,
Careful with the compass, it will need to be tilt compensated which is not trivial.
Depends on how much maths you've done I suppose.
Given a compass bearing and accelerometer data I could probably make the compass accurate without having done it before.
I had (have?) a remote control plane. It liked to nose dive and the plastic propeller didnt like it too much.
It was a cheap one though. I'm looking in to getting a pricier helicopter.
Hello people, i already have the beta 2 of arducopter, but right know i dont have time to translate (weakness), but if you wish to see more pictures and know a little bit of spanish, enter here:
You're English is very good; don't worry too much about translations; a picture is worth a thousand words, and we're excited to see a video if you ever get the time to do so. That's an excellent helicopter you put together. It's cool that people are coming up with complex ideas and getting them to work.
Ok, i had a big problem, but i already solve it, the vibration of the main rotor, cause a lot of interference with the accelerometer, i almost leave this project for that. But i was googling around, and i found a group of student that try to make the same like me.. jejej here is the link: http://www.mne.psu.edu/me415/fall04/boeing4/
Well wathever, i used, i dont how to say it, in spanish are call "Ligas" links, is plastic bands. To put the accelerometer in the center and adsorb the vibrations. For my surprise i be able to reduce 90% to 95% of the vibration.
No yet... the project will be stopped for some time. I need to buy a new helicopter ($$$)... But soon ill finish the sensors and share the code. =)
There is another guy that is working right now in the project... (he have a better heli).
And remember the Arducopter project is no for a fully autonomous helicopter is just for semi-autonomus heli, to stabilize it and make it easy to fly. =)
The arduplane project is a fully automated airplane....
