main.cpp

00001 /*   Calculating Roll, Pitch and Yaw angles from IMU
00002 *
00003 *    @author: Baser Kandehir 
00004 *    @date: August 5, 2015
00005 *    @license: MIT license
00006 *     
00007 *   Copyright (c) 2015, Baser Kandehir, baser.kandehir@ieee.metu.edu.tr
00008 *
00009 *   Permission is hereby granted, free of charge, to any person obtaining a copy
00010 *   of this software and associated documentation files (the "Software"), to deal
00011 *   in the Software without restriction, including without limitation the rights
00012 *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00013 *   copies of the Software, and to permit persons to whom the Software is
00014 *   furnished to do so, subject to the following conditions:
00015 *
00016 *   The above copyright notice and this permission notice shall be included in
00017 *   all copies or substantial portions of the Software.
00018 *
00019 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00020 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00021 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00022 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00023 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00024 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00025 *   THE SOFTWARE.
00026 *   
00027 *    @description of the program: 
00028 *
00029 *   Program can calculate roll, pitch and yaw angles from the raw data that comes 
00030 *   from IMU. Yaw angle is compensated for tilt. All the angles are sent to the matlab
00031 *   for further processing.
00032 *     
00033 */
00034 
00035 #include "mbed.h"
00036 #include "HMC5883L.h"
00037 #include "MPU6050.h"
00038 #include "ledControl.h"
00039 
00040 Serial pc(USBTX,USBRX);    
00041 MPU6050 mpu6050;           
00042 HMC5883L hmc5883l;    
00043 Ticker toggler1;
00044 Ticker filter;   
00045 Ticker compass;        
00046 
00047 void toggle_led1();
00048 void toggle_led2();
00049 void compFilter();
00050 void tiltCompensatedAngle();
00051 
00052 float pitchAngle = 0;
00053 float rollAngle = 0;
00054 float yawAngle = 0;
00055 
00056 int main() 
00057 {
00058     pc.baud(9600);                                 // baud rate: 9600
00059     mpu6050.whoAmI();                              // Communication test: WHO_AM_I register reading 
00060     mpu6050.calibrate(accelBias,gyroBias);         // Calibrate MPU6050 and load biases into bias registers
00061     mpu6050.init();                                // Initialize the sensor
00062     hmc5883l.init();
00063     filter.attach(&compFilter,    0.005);              // Call the complementaryFilter func.  every 5 ms (200 Hz sampling period)
00064     compass.attach(&tiltCompensatedAngle, 0.015);      // Call the tiltCompensatedAngle func. every 15 ms (75 Hz sampling period)
00065     while(1) 
00066     {
00067         pc.printf("%.1f,%.1f,%.1f\r\n",rollAngle,pitchAngle,yawAngle);  // send data to matlab
00068         wait_ms(40);
00069     }
00070 }
00071 
00072 void toggle_led1() {ledToggle(1);}
00073 void toggle_led2() {ledToggle(2);}
00074 
00075 /* This function is created to avoid address error that caused from Ticker.attach func */ 
00076 void compFilter() {mpu6050.complementaryFilter(&pitchAngle, &rollAngle);}
00077 
00078 /* Tilt compensated compass data */
00079 // Works well for tilt in +/- 50 deg range
00080 void tiltCompensatedAngle() 
00081 {   
00082     float mag_Data[3], Xh, Yh;
00083     hmc5883l.readMagData(mag_Data);
00084     
00085     Xh = mag_Data[0] * cos(rollAngle*PI/180) - mag_Data[2] * sin(rollAngle*PI/180) ;
00086     
00087     Yh = mag_Data[0] * sin(pitchAngle*PI/180) * sin(rollAngle*PI/180) + 
00088     mag_Data[1] * cos(pitchAngle*PI/180) -
00089     mag_Data[2] * sin(pitchAngle*PI/180) * cos(rollAngle*PI/180) ;
00090     
00091     /* Calculate the compensated heading angle */
00092     double heading = atan2(Yh, Xh);
00093     
00094     // After calculating heading declination angle should be added to heading which is the error of the magnetic field in specific location.
00095     // declinationAngle can be found here http://www.magnetic-declination.com/
00096     // For Ankara (my location) declinationAngle is ~5.5 degrees (0.096 radians)
00097     float declinationAngle = 0.096;
00098     heading += declinationAngle;
00099     
00100     // Correct for when signs are reversed.
00101     if(heading < 0)
00102         heading += 2*PI;
00103     
00104     // Check for wrap due to addition of declination.
00105     if(heading > 2*PI)
00106         heading -= 2*PI;
00107     
00108     /* Convert radian to degrees */
00109     heading = heading * 180 / PI;  
00110     
00111     yawAngle = heading; 
00112 }