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Omni-Holder.ino
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Omni-Holder.ino
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#include <PID_v1.h>
#include "MegunoLink.h"
#include <Filter.h>
#include <Kalman.h> // Source: https://github.com/TKJElectronics/KalmanFilter
#include <Wire.h>
#include <Servo.h>
ExponentialFilter<long> ACCFilterX(25, 0); //DO NOT GO OVER 9000!!!!
ExponentialFilter<long> ACCFilterY(15, 0); //DO NOT GO OVER 9000!!!!
#define RESTRICT_PITCH // Comment out to restrict roll to ±90deg instead - please read: http ://www.freescale.com/files/sensors/doc/app_note/AN3461.pdf
Kalman kalmanX; // Create the Kalman instances
Kalman kalmanY;
Servo Servo1; // First Servo off the chassis
Servo Servo2; // Second Servo off the chassis
int Servo1Pos = 0;
int Servo2Pos = 0;
const uint8_t IMUAddress = 0x68; // AD0 is logic low on the PCB
const uint16_t I2C_TIMEOUT = 1000; // Used to check for errors in I2C communication
uint8_t i2cWrite(uint8_t registerAddress, uint8_t data, bool sendStop) {
return i2cWrite(registerAddress, &data, 1, sendStop); // Returns 0 on success
}
uint8_t i2cWrite(uint8_t registerAddress, uint8_t *data, uint8_t length, bool sendStop) {
Wire.beginTransmission(IMUAddress);
Wire.write(registerAddress);
Wire.write(data, length);
uint8_t rcode = Wire.endTransmission(sendStop); // Returns 0 on success
if (rcode) {
Serial.print(F("i2cWrite failed: "));
Serial.println(rcode);
}
return rcode; // See: http://arduino.cc/en/Reference/WireEndTransmission
}
uint8_t i2cRead(uint8_t registerAddress, uint8_t *data, uint8_t nbytes) {
uint32_t timeOutTimer;
Wire.beginTransmission(IMUAddress);
Wire.write(registerAddress);
uint8_t rcode = Wire.endTransmission(false); // Don't release the bus
if (rcode) {
Serial.print(F("i2cRead failed: "));
Serial.println(rcode);
return rcode; // See: http://arduino.cc/en/Reference/WireEndTransmission
}
Wire.requestFrom(IMUAddress, nbytes, (uint8_t)true); // Send a repeated start and then release the bus after reading
for (uint8_t i = 0; i < nbytes; i++) {
if (Wire.available())
data[i] = Wire.read();
else {
timeOutTimer = micros();
while (((micros() - timeOutTimer) < I2C_TIMEOUT) && !Wire.available());
if (Wire.available())
data[i] = Wire.read();
else {
Serial.println(F("i2cRead timeout"));
return 5; // This error value is not already taken by endTransmission
}
}
}
return 0; // Success
}
/* IMU Data */
double accX, accY, accZ;
double gyroX, gyroY, gyroZ;
int16_t tempRaw;
double gyroXangle, gyroYangle; // Angle calculate using the gyro only
double compAngleX, compAngleY; // Calculated angle using a complementary filter
double kalAngleX, kalAngleY; // Calculated angle using a Kalman filter
uint32_t timer;
uint8_t i2cData[14]; // Buffer for I2C data
// TODO: Make calibration routine
void setup() {
Serial.begin(115200);
Wire.begin();
#if ARDUINO >= 157
Wire.setClock(400000UL); // Set I2C frequency to 400kHz
#else
TWBR = ((F_CPU / 400000UL) - 16) / 2; // Set I2C frequency to 400kHz
#endif
Servo1.attach(10); // attaches the servo on D11 to the servo object
Servo2.attach(11); // Second servo on D11
/*delay(50);
Servo1.write(0); // These are command checks to see if the servos work and
Servo2.write(60); // to help w/ the initial installation.
delay(500); // Make sure these movements are clear from the rest of the chassis.
Servo1.write(180);
Servo2.write(120);
delay(500);
Servo1.write(0);
Servo2.write(90);
delay(500);*/
i2cData[0] = 7; // Set the sample rate to 1000Hz - 8kHz/(7+1) = 1000Hz
i2cData[1] = 0x00; // Disable FSYNC and set 260 Hz Acc filtering, 256 Hz Gyro filtering, 8 KHz sampling
i2cData[2] = 0x00; // Set Gyro Full Scale Range to ±250deg/s
i2cData[3] = 0x00; // Set Accelerometer Full Scale Range to ±2g
while (i2cWrite(0x19, i2cData, 4, false)); // Write to all four registers at once
while (i2cWrite(0x6B, 0x01, true)); // PLL with X axis gyroscope reference and disable sleep mode
while (i2cRead(0x75, i2cData, 1));
if (i2cData[0] != 0x68) { // Read "WHO_AM_I" register
Serial.print(F("Error reading sensor"));
while (1);
}
delay(100); // Wait for sensor to stabilize
/* Set kalman and gyro starting angle */
while (i2cRead(0x3B, i2cData, 6));
double last_accX = accX, last_accY = accY, last_accZ = accZ;
accX = (int16_t)((i2cData[0] << 8) | i2cData[1]);
accY = (int16_t)((i2cData[2] << 8) | i2cData[3]);
accZ = (int16_t)((i2cData[4] << 8) | i2cData[5]);
// Source: http://www.freescale.com/files/sensors/doc/app_note/AN3461.pdf eq. 25 and eq. 26
// atan2 outputs the value of -π to π (radians) - see http://en.wikipedia.org/wiki/Atan2
// It is then converted from radians to degrees
#ifdef RESTRICT_PITCH // Eq. 25 and 26
double roll = atan2(accY, accZ) * RAD_TO_DEG;
double pitch = atan(-accX / sqrt(accY * accY + accZ * accZ)) * RAD_TO_DEG;
#else // Eq. 28 and 29
double roll = atan(accY / sqrt(accX * accX + accZ * accZ)) * RAD_TO_DEG;
double pitch = atan2(-accX, accZ) * RAD_TO_DEG;
#endif
kalmanX.setAngle(roll); // Set starting angle
kalmanY.setAngle(pitch);
gyroXangle = roll;
gyroYangle = pitch;
compAngleX = roll;
compAngleY = pitch;
timer = micros();
}
void loop() {
/* Update all the values */
while (i2cRead(0x3B, i2cData, 14));
accX = (int16_t)((i2cData[0] << 8) | i2cData[1]);
accY = (int16_t)((i2cData[2] << 8) | i2cData[3]);
accZ = (int16_t)((i2cData[4] << 8) | i2cData[5]);
tempRaw = (int16_t)((i2cData[6] << 8) | i2cData[7]);
gyroX = (int16_t)((i2cData[8] << 8) | i2cData[9]);
gyroY = (int16_t)((i2cData[10] << 8) | i2cData[11]);
gyroZ = (int16_t)((i2cData[12] << 8) | i2cData[13]);;
double dt = (double)(micros() - timer) / 1000000; // Calculate delta time
timer = micros();
// Source: http://www.freescale.com/files/sensors/doc/app_note/AN3461.pdf eq. 25 and eq. 26
// atan2 outputs the value of -π to π (radians) - see http://en.wikipedia.org/wiki/Atan2
// It is then converted from radians to degrees
#ifdef RESTRICT_PITCH // Eq. 25 and 26
double roll = atan2(accY, accZ) * RAD_TO_DEG;
double pitch = atan(-accX / sqrt(accY * accY + accZ * accZ)) * RAD_TO_DEG;
#else // Eq. 28 and 29
double roll = atan(accY / sqrt(accX * accX + accZ * accZ)) * RAD_TO_DEG;
double pitch = atan2(-accX, accZ) * RAD_TO_DEG;
#endif
double gyroXrate = gyroX / 131.0; // Convert to deg/s
double gyroYrate = gyroY / 131.0; // Convert to deg/s
#ifdef RESTRICT_PITCH
// This fixes the transition problem when the accelerometer angle jumps between -180 and 180 degrees
if ((roll < -90 && kalAngleX > 90) || (roll > 90 && kalAngleX < -90)) {
kalmanX.setAngle(roll);
compAngleX = roll;
kalAngleX = roll;
gyroXangle = roll;
}
else
kalAngleX = kalmanX.getAngle(roll, gyroXrate, dt); // Calculate the angle using a Kalman filter
if (abs(kalAngleX) > 90)
gyroYrate = -gyroYrate; // Invert rate, so it fits the restriced accelerometer reading
kalAngleY = kalmanY.getAngle(pitch, gyroYrate, dt);
#else
// This fixes the transition problem when the accelerometer angle jumps between -180 and 180 degrees
if ((pitch < -90 && kalAngleY > 90) || (pitch > 90 && kalAngleY < -90)) {
kalmanY.setAngle(pitch);
compAngleY = pitch;
kalAngleY = pitch;
gyroYangle = pitch;
}
else
kalAngleY = kalmanY.getAngle(pitch, gyroYrate, dt); // Calculate the angle using a Kalman filter
if (abs(kalAngleY) > 90)
gyroXrate = -gyroXrate; // Invert rate, so it fits the restriced accelerometer reading
kalAngleX = kalmanX.getAngle(roll, gyroXrate, dt); // Calculate the angle using a Kalman filter
#endif
gyroXangle += gyroXrate * dt; // Calculate gyro angle without any filter
gyroYangle += gyroYrate * dt;
//gyroXangle += kalmanX.getRate() * dt; // Calculate gyro angle using the unbiased rate
//gyroYangle += kalmanY.getRate() * dt;
compAngleX = 0.93 * (compAngleX + gyroXrate * dt) + 0.07 * roll; // Calculate the angle using a Complimentary filter
compAngleY = 0.93 * (compAngleY + gyroYrate * dt) + 0.07 * pitch;
// Reset the gyro angle when it has drifted too much
if (gyroXangle < -180 || gyroXangle > 180)
gyroXangle = kalAngleX;
if (gyroYangle < -180 || gyroYangle > 180)
gyroYangle = kalAngleY;
ACCFilterX.Filter(accX); //filtered acceleration
Servo2.write(-compAngleY + 90 - ACCFilterX.Current() / 4000);
delay(2);
ACCFilterY.Filter(accY);
Servo1.write(-compAngleX + 90 - ACCFilterY.Current() / 4000);
delay(2);
}