NOT FINISHED YET!!! My first try to get a self built fully working Quadrocopter based on an mbed, a self built frame and some other more or less cheap parts.
IMU_Filter/IMU_Filter.cpp
- Committer:
- maetugr
- Date:
- 2013-06-12
- Revision:
- 37:34917f7c10ae
- Parent:
- 34:3aa1cbcde59d
File content as of revision 37:34917f7c10ae:
#include "IMU_Filter.h" // MARG #define PI 3.1415926535897932384626433832795 #define Kp 2.0f // proportional gain governs rate of convergence to accelerometer/magnetometer #define Ki 0.005f // integral gain governs rate of convergence of gyroscope biases IMU_Filter::IMU_Filter() { for(int i=0; i<3; i++) angle[i]=0; // MARG q0 = 1; q1 = 0; q2 = 0; q3 = 0; exInt = 0; eyInt = 0; ezInt = 0; } void IMU_Filter::compute(float dt, const float * Gyro_data, const float * Acc_data) { // calculate angles for each sensor for(int i = 0; i < 3; i++) d_Gyro_angle[i] = Gyro_data[i] *dt; get_Acc_angle(Acc_data); // Complementary Filter #if 0 // (formula from http://diydrones.com/m/discussion?id=705844%3ATopic%3A669858) angle[0] = (0.999*(angle[0] + d_Gyro_angle[0]))+(0.001*(Acc_angle[0])); angle[1] = (0.999*(angle[1] + d_Gyro_angle[1]))+(0.001*(Acc_angle[1]));// + 3)); // TODO Offset accelerometer einstellen angle[2] += d_Gyro_angle[2]; // gyro only here TODO: Compass + 3D #endif #if 0 // alte berechnung, vielleicht Accelerometer zu stark gewichtet angle[0] += (Acc.angle[0] - angle[0])/50 + d_Gyro_angle[0]; angle[1] += (Acc.angle[1] - angle[1])/50 + d_Gyro_angle[1];// TODO Offset accelerometer einstellen //tempangle += (Comp.get_angle() - tempangle)/50 + Gyro.data[2] *dt/15000000.0; angle[2] = Gyro_angle[2]; // gyro only here #endif #if 0 // neuer Test 2 (funktioniert wahrscheinlich nicht, denkfehler) angle[0] += Gyro_angle[0] * 0.98 + Acc.angle[0] * 0.02; angle[1] += Gyro_angle[1] * 0.98 + (Acc.angle[1] + 3) * 0.02; // TODO: Calibrierung Acc angle[2] = Gyro_angle[2]; // gyro only here #endif #if 0 // all gyro only for(int i = 0; i < 3; i++) angle[i] += d_Gyro_angle[i]; #endif // MARG #if 1 // (from http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/) float radGyro[3]; for(int i=0; i<3; i++) // Radians per second radGyro[i] = Gyro_data[i] * PI / 180; IMUupdate(dt/2, radGyro[0], radGyro[1], radGyro[2], Acc_data[0], Acc_data[1], Acc_data[2]); float rangle[3]; // calculate angles in radians from quternion output rangle[0] = atan2(2*q0*q1 + 2*q2*q3, 1 - 2*(q1*q1 + q2*q2)); // from Wiki rangle[1] = asin(2*q0*q2 - 2*q3*q1); rangle[2] = atan2(2*q0*q3 + 2*q1*q2, 1 - 2*(q2*q2 + q3*q3)); // TODO // Pitch should have a range of +/-90 degrees. // After you pitch past vertical (90 degrees) your roll and yaw value should swing 180 degrees. // A pitch value of 100 degrees is measured as a pitch of 80 degrees and inverted flight (roll = 180 degrees). // Another example is a pitch of 180 degrees (upside down). This is measured as a level pitch (0 degrees) and a roll of 180 degrees. // And I think this solves the upside down issue... // Handle roll reversal when inverted /*if (Acc_data[2] < 0) { if (Acc_data[0] < 0) { rangle[1] = (180 - rangle[1]); } else { rangle[1] = (-180 - rangle[1]); } }*/ for(int i=0; i<3; i++) // angle in degree angle[i] = rangle[i] * 180 / PI; #endif } void IMU_Filter::get_Acc_angle(const float * Acc_data) { // calculate the angles for roll and pitch (0,1) float R = sqrt(pow((float)Acc_data[0],2) + pow((float)Acc_data[1],2) + pow((float)Acc_data[2],2)); float temp[3]; temp[0] = -(Rad2Deg * acos(Acc_data[1] / R)-90); temp[1] = Rad2Deg * acos(Acc_data[0] / R)-90; temp[2] = Rad2Deg * acos(Acc_data[2] / R); for(int i = 0;i < 3; i++) if (temp[i] > -360 && temp[i] < 360) Acc_angle[i] = temp[i]; } // MARG void IMU_Filter::IMUupdate(float halfT, float gx, float gy, float gz, float ax, float ay, float az) { float norm; float vx, vy, vz; float ex, ey, ez; // normalise the measurements norm = sqrt(ax*ax + ay*ay + az*az); if(norm == 0.0f) return; ax = ax / norm; ay = ay / norm; az = az / norm; // estimated direction of gravity vx = 2*(q1*q3 - q0*q2); vy = 2*(q0*q1 + q2*q3); vz = q0*q0 - q1*q1 - q2*q2 + q3*q3; // error is sum of cross product between reference direction of field and direction measured by sensor ex = (ay*vz - az*vy); ey = (az*vx - ax*vz); ez = (ax*vy - ay*vx); // integral error scaled integral gain exInt = exInt + ex*Ki; eyInt = eyInt + ey*Ki; ezInt = ezInt + ez*Ki; // adjusted gyroscope measurements gx = gx + Kp*ex + exInt; gy = gy + Kp*ey + eyInt; gz = gz + Kp*ez + ezInt; // integrate quaternion rate and normalise q0 = q0 + (-q1*gx - q2*gy - q3*gz)*halfT; q1 = q1 + (q0*gx + q2*gz - q3*gy)*halfT; q2 = q2 + (q0*gy - q1*gz + q3*gx)*halfT; q3 = q3 + (q0*gz + q1*gy - q2*gx)*halfT; // normalise quaternion norm = sqrt(q0*q0 + q1*q1 + q2*q2 + q3*q3); q0 = q0 / norm; q1 = q1 / norm; q2 = q2 / norm; q3 = q3 / norm; }