semin ahn / Mbed OS zeta_stm_kinetic

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependencies:   BufferedSerial

MPU9250/MadgwickAHRS.cpp@0:4ff8aeb3e4d1, 2021-04-02 (annotated)

Committer:
_seminahn
Date:
Fri Apr 02 05:24:49 2021 +0000
Revision:
0:4ff8aeb3e4d1
top_module

Who changed what in which revision?

UserRevisionLine numberNew contents of line
_seminahn 0:4ff8aeb3e4d1 1 //=============================================================================================
_seminahn 0:4ff8aeb3e4d1 2 // MadgwickAHRS.c
_seminahn 0:4ff8aeb3e4d1 3 //=============================================================================================
_seminahn 0:4ff8aeb3e4d1 4 //
_seminahn 0:4ff8aeb3e4d1 5 // Implementation of Madgwick's IMU and AHRS algorithms.
_seminahn 0:4ff8aeb3e4d1 6 // See: http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/
_seminahn 0:4ff8aeb3e4d1 7 //
_seminahn 0:4ff8aeb3e4d1 8 // From the x-io website "Open-source resources available on this website are
_seminahn 0:4ff8aeb3e4d1 9 // provided under the GNU General Public Licence unless an alternative licence
_seminahn 0:4ff8aeb3e4d1 10 // is provided in source."
_seminahn 0:4ff8aeb3e4d1 11 //
_seminahn 0:4ff8aeb3e4d1 12 // Date Author Notes
_seminahn 0:4ff8aeb3e4d1 13 // 29/09/2011 SOH Madgwick Initial release
_seminahn 0:4ff8aeb3e4d1 14 // 02/10/2011 SOH Madgwick Optimised for reduced CPU load
_seminahn 0:4ff8aeb3e4d1 15 // 19/02/2012 SOH Madgwick Magnetometer measurement is normalised
_seminahn 0:4ff8aeb3e4d1 16 //
_seminahn 0:4ff8aeb3e4d1 17 //=============================================================================================
_seminahn 0:4ff8aeb3e4d1 18
_seminahn 0:4ff8aeb3e4d1 19 //-------------------------------------------------------------------------------------------
_seminahn 0:4ff8aeb3e4d1 20 // Header files
_seminahn 0:4ff8aeb3e4d1 21
_seminahn 0:4ff8aeb3e4d1 22 #include "MadgwickAHRS.h"
_seminahn 0:4ff8aeb3e4d1 23 #include <math.h>
_seminahn 0:4ff8aeb3e4d1 24 #include <stdio.h>
_seminahn 0:4ff8aeb3e4d1 25 #include "ros.h"
_seminahn 0:4ff8aeb3e4d1 26
_seminahn 0:4ff8aeb3e4d1 27 #if (NO_ROS)
_seminahn 0:4ff8aeb3e4d1 28 extern Serial pc;
_seminahn 0:4ff8aeb3e4d1 29 #else
_seminahn 0:4ff8aeb3e4d1 30 extern ros::NodeHandle nh;
_seminahn 0:4ff8aeb3e4d1 31 #endif
_seminahn 0:4ff8aeb3e4d1 32 //-------------------------------------------------------------------------------------------
_seminahn 0:4ff8aeb3e4d1 33 // Definitions
_seminahn 0:4ff8aeb3e4d1 34
_seminahn 0:4ff8aeb3e4d1 35 #define sampleFreqDef 512.0f // sample frequency in Hz
_seminahn 0:4ff8aeb3e4d1 36 #define betaDef 0.1f // 2 * proportional gain
_seminahn 0:4ff8aeb3e4d1 37
_seminahn 0:4ff8aeb3e4d1 38
_seminahn 0:4ff8aeb3e4d1 39
_seminahn 0:4ff8aeb3e4d1 40 //============================================================================================
_seminahn 0:4ff8aeb3e4d1 41 // Functions
_seminahn 0:4ff8aeb3e4d1 42
_seminahn 0:4ff8aeb3e4d1 43 //-------------------------------------------------------------------------------------------
_seminahn 0:4ff8aeb3e4d1 44 // AHRS algorithm update
_seminahn 0:4ff8aeb3e4d1 45
_seminahn 0:4ff8aeb3e4d1 46 Madgwick::Madgwick() {
_seminahn 0:4ff8aeb3e4d1 47 beta = betaDef;
_seminahn 0:4ff8aeb3e4d1 48 q0 = 1.0f;
_seminahn 0:4ff8aeb3e4d1 49 q1 = 0.0f;
_seminahn 0:4ff8aeb3e4d1 50 q2 = 0.0f;
_seminahn 0:4ff8aeb3e4d1 51 q3 = 0.0f;
_seminahn 0:4ff8aeb3e4d1 52 invSampleFreq = 1.0f / sampleFreqDef;
_seminahn 0:4ff8aeb3e4d1 53
_seminahn 0:4ff8aeb3e4d1 54 anglesComputed = 0;
_seminahn 0:4ff8aeb3e4d1 55
_seminahn 0:4ff8aeb3e4d1 56 }
_seminahn 0:4ff8aeb3e4d1 57
_seminahn 0:4ff8aeb3e4d1 58 void Madgwick::update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) {
_seminahn 0:4ff8aeb3e4d1 59 float recipNorm;
_seminahn 0:4ff8aeb3e4d1 60 float s0, s1, s2, s3;
_seminahn 0:4ff8aeb3e4d1 61 float qDot1, qDot2, qDot3, qDot4;
_seminahn 0:4ff8aeb3e4d1 62 float hx, hy;
_seminahn 0:4ff8aeb3e4d1 63 float _2q0mx, _2q0my, _2q0mz, _2q1mx, _2bx, _2bz, _4bx, _4bz, _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;
_seminahn 0:4ff8aeb3e4d1 64
_seminahn 0:4ff8aeb3e4d1 65
_seminahn 0:4ff8aeb3e4d1 66 // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)
_seminahn 0:4ff8aeb3e4d1 67 if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
_seminahn 0:4ff8aeb3e4d1 68 updateIMU(gx, gy, gz, ax, ay, az);
_seminahn 0:4ff8aeb3e4d1 69 return;
_seminahn 0:4ff8aeb3e4d1 70 }
_seminahn 0:4ff8aeb3e4d1 71
_seminahn 0:4ff8aeb3e4d1 72 // Convert gyroscope degrees/sec to radians/sec
_seminahn 0:4ff8aeb3e4d1 73 gx *= 0.0174533f;
_seminahn 0:4ff8aeb3e4d1 74 gy *= 0.0174533f;
_seminahn 0:4ff8aeb3e4d1 75 gz *= 0.0174533f;
_seminahn 0:4ff8aeb3e4d1 76
_seminahn 0:4ff8aeb3e4d1 77 // Rate of change of quaternion from gyroscope
_seminahn 0:4ff8aeb3e4d1 78 qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
_seminahn 0:4ff8aeb3e4d1 79 qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
_seminahn 0:4ff8aeb3e4d1 80 qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
_seminahn 0:4ff8aeb3e4d1 81 qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
_seminahn 0:4ff8aeb3e4d1 82
_seminahn 0:4ff8aeb3e4d1 83 // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
_seminahn 0:4ff8aeb3e4d1 84 if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
_seminahn 0:4ff8aeb3e4d1 85
_seminahn 0:4ff8aeb3e4d1 86 // Normalise accelerometer measurement
_seminahn 0:4ff8aeb3e4d1 87 recipNorm = invSqrt(ax * ax + ay * ay + az * az);
_seminahn 0:4ff8aeb3e4d1 88 ax *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 89 ay *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 90 az *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 91
_seminahn 0:4ff8aeb3e4d1 92 // Normalise magnetometer measurement
_seminahn 0:4ff8aeb3e4d1 93 recipNorm = invSqrt(mx * mx + my * my + mz * mz);
_seminahn 0:4ff8aeb3e4d1 94 mx *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 95 my *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 96 mz *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 97
_seminahn 0:4ff8aeb3e4d1 98 // Auxiliary variables to avoid repeated arithmetic
_seminahn 0:4ff8aeb3e4d1 99 _2q0mx = 2.0f * q0 * mx;
_seminahn 0:4ff8aeb3e4d1 100 _2q0my = 2.0f * q0 * my;
_seminahn 0:4ff8aeb3e4d1 101 _2q0mz = 2.0f * q0 * mz;
_seminahn 0:4ff8aeb3e4d1 102 _2q1mx = 2.0f * q1 * mx;
_seminahn 0:4ff8aeb3e4d1 103 _2q0 = 2.0f * q0;
_seminahn 0:4ff8aeb3e4d1 104 _2q1 = 2.0f * q1;
_seminahn 0:4ff8aeb3e4d1 105 _2q2 = 2.0f * q2;
_seminahn 0:4ff8aeb3e4d1 106 _2q3 = 2.0f * q3;
_seminahn 0:4ff8aeb3e4d1 107 _2q0q2 = 2.0f * q0 * q2;
_seminahn 0:4ff8aeb3e4d1 108 _2q2q3 = 2.0f * q2 * q3;
_seminahn 0:4ff8aeb3e4d1 109 q0q0 = q0 * q0;
_seminahn 0:4ff8aeb3e4d1 110 q0q1 = q0 * q1;
_seminahn 0:4ff8aeb3e4d1 111 q0q2 = q0 * q2;
_seminahn 0:4ff8aeb3e4d1 112 q0q3 = q0 * q3;
_seminahn 0:4ff8aeb3e4d1 113 q1q1 = q1 * q1;
_seminahn 0:4ff8aeb3e4d1 114 q1q2 = q1 * q2;
_seminahn 0:4ff8aeb3e4d1 115 q1q3 = q1 * q3;
_seminahn 0:4ff8aeb3e4d1 116 q2q2 = q2 * q2;
_seminahn 0:4ff8aeb3e4d1 117 q2q3 = q2 * q3;
_seminahn 0:4ff8aeb3e4d1 118 q3q3 = q3 * q3;
_seminahn 0:4ff8aeb3e4d1 119
_seminahn 0:4ff8aeb3e4d1 120 // Reference direction of Earth's magnetic field
_seminahn 0:4ff8aeb3e4d1 121 hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;
_seminahn 0:4ff8aeb3e4d1 122 hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;
_seminahn 0:4ff8aeb3e4d1 123 _2bx = sqrtf(hx * hx + hy * hy);
_seminahn 0:4ff8aeb3e4d1 124 _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;
_seminahn 0:4ff8aeb3e4d1 125 _4bx = 2.0f * _2bx;
_seminahn 0:4ff8aeb3e4d1 126 _4bz = 2.0f * _2bz;
_seminahn 0:4ff8aeb3e4d1 127
_seminahn 0:4ff8aeb3e4d1 128 // Gradient decent algorithm corrective step
_seminahn 0:4ff8aeb3e4d1 129 s0 = -_2q2 * (2.0f * q1q3 - _2q0q2 - ax) + _2q1 * (2.0f * q0q1 + _2q2q3 - ay) - _2bz * q2 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q3 + _2bz * q1) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q2 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
_seminahn 0:4ff8aeb3e4d1 130 s1 = _2q3 * (2.0f * q1q3 - _2q0q2 - ax) + _2q0 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q1 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + _2bz * q3 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q2 + _2bz * q0) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q3 - _4bz * q1) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
_seminahn 0:4ff8aeb3e4d1 131 s2 = -_2q0 * (2.0f * q1q3 - _2q0q2 - ax) + _2q3 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q2 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + (-_4bx * q2 - _2bz * q0) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q1 + _2bz * q3) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q0 - _4bz * q2) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
_seminahn 0:4ff8aeb3e4d1 132 s3 = _2q1 * (2.0f * q1q3 - _2q0q2 - ax) + _2q2 * (2.0f * q0q1 + _2q2q3 - ay) + (-_4bx * q3 + _2bz * q1) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q0 + _2bz * q2) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q1 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
_seminahn 0:4ff8aeb3e4d1 133 recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
_seminahn 0:4ff8aeb3e4d1 134 s0 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 135 s1 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 136 s2 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 137 s3 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 138
_seminahn 0:4ff8aeb3e4d1 139 // Apply feedback step
_seminahn 0:4ff8aeb3e4d1 140 qDot1 -= beta * s0;
_seminahn 0:4ff8aeb3e4d1 141 qDot2 -= beta * s1;
_seminahn 0:4ff8aeb3e4d1 142 qDot3 -= beta * s2;
_seminahn 0:4ff8aeb3e4d1 143 qDot4 -= beta * s3;
_seminahn 0:4ff8aeb3e4d1 144 }
_seminahn 0:4ff8aeb3e4d1 145
_seminahn 0:4ff8aeb3e4d1 146 // Integrate rate of change of quaternion to yield quaternion
_seminahn 0:4ff8aeb3e4d1 147 q0 += qDot1 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 148 q1 += qDot2 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 149 q2 += qDot3 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 150 q3 += qDot4 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 151
_seminahn 0:4ff8aeb3e4d1 152 // Normalise quaternion
_seminahn 0:4ff8aeb3e4d1 153 recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
_seminahn 0:4ff8aeb3e4d1 154 q0 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 155 q1 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 156 q2 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 157 q3 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 158 anglesComputed = 0;
_seminahn 0:4ff8aeb3e4d1 159 }
_seminahn 0:4ff8aeb3e4d1 160
_seminahn 0:4ff8aeb3e4d1 161 //-------------------------------------------------------------------------------------------
_seminahn 0:4ff8aeb3e4d1 162 // IMU algorithm update
_seminahn 0:4ff8aeb3e4d1 163
_seminahn 0:4ff8aeb3e4d1 164 void Madgwick::updateIMU(float gx, float gy, float gz, float ax, float ay, float az) {
_seminahn 0:4ff8aeb3e4d1 165 float recipNorm;
_seminahn 0:4ff8aeb3e4d1 166 float s0, s1, s2, s3;
_seminahn 0:4ff8aeb3e4d1 167 float qDot1, qDot2, qDot3, qDot4;
_seminahn 0:4ff8aeb3e4d1 168 float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;
_seminahn 0:4ff8aeb3e4d1 169 char tempstr[64] = {};
_seminahn 0:4ff8aeb3e4d1 170 //pc.printf("q_pre: %.3f %.3f %.3f %.3f\n\r",q0,q1,q2,q3);
_seminahn 0:4ff8aeb3e4d1 171 /*
_seminahn 0:4ff8aeb3e4d1 172 sprintf(tempstr,"%f %f %f %f %f %f",gx,gy,gz,ax,ay,az);
_seminahn 0:4ff8aeb3e4d1 173 nh.loginfo("gx gy gz ax ay az");
_seminahn 0:4ff8aeb3e4d1 174 nh.loginfo(tempstr);
_seminahn 0:4ff8aeb3e4d1 175 */
_seminahn 0:4ff8aeb3e4d1 176
_seminahn 0:4ff8aeb3e4d1 177 // Convert gyroscope degrees/sec to radians/sec
_seminahn 0:4ff8aeb3e4d1 178
_seminahn 0:4ff8aeb3e4d1 179 gx *= 0.0174533f;
_seminahn 0:4ff8aeb3e4d1 180 gy *= 0.0174533f;
_seminahn 0:4ff8aeb3e4d1 181 gz *= 0.0174533f;
_seminahn 0:4ff8aeb3e4d1 182 //pc.printf("%f %f %f %f %f %f \n\r",gx,gy,gz,ax,ay,az);
_seminahn 0:4ff8aeb3e4d1 183 // Rate of change of quaternion from gyroscope
_seminahn 0:4ff8aeb3e4d1 184
_seminahn 0:4ff8aeb3e4d1 185 qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
_seminahn 0:4ff8aeb3e4d1 186 qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
_seminahn 0:4ff8aeb3e4d1 187 qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
_seminahn 0:4ff8aeb3e4d1 188 qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
_seminahn 0:4ff8aeb3e4d1 189 //pc.printf("%.5f %.5f %.5f %.5f ",qDot1,qDot2,qDot3,qDot4);
_seminahn 0:4ff8aeb3e4d1 190 // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
_seminahn 0:4ff8aeb3e4d1 191 if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
_seminahn 0:4ff8aeb3e4d1 192
_seminahn 0:4ff8aeb3e4d1 193 // Normalise accelerometer measurement
_seminahn 0:4ff8aeb3e4d1 194 recipNorm = invSqrt(ax * ax + ay * ay + az * az);
_seminahn 0:4ff8aeb3e4d1 195 //pc.printf("nomalized acc: %.5f\n\r",recipNorm);
_seminahn 0:4ff8aeb3e4d1 196 ax *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 197 ay *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 198 az *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 199
_seminahn 0:4ff8aeb3e4d1 200 // Auxiliary variables to avoid repeated arithmetic
_seminahn 0:4ff8aeb3e4d1 201 _2q0 = 2.0f * q0;
_seminahn 0:4ff8aeb3e4d1 202 _2q1 = 2.0f * q1;
_seminahn 0:4ff8aeb3e4d1 203 _2q2 = 2.0f * q2;
_seminahn 0:4ff8aeb3e4d1 204 _2q3 = 2.0f * q3;
_seminahn 0:4ff8aeb3e4d1 205 _4q0 = 4.0f * q0;
_seminahn 0:4ff8aeb3e4d1 206 _4q1 = 4.0f * q1;
_seminahn 0:4ff8aeb3e4d1 207 _4q2 = 4.0f * q2;
_seminahn 0:4ff8aeb3e4d1 208 _8q1 = 8.0f * q1;
_seminahn 0:4ff8aeb3e4d1 209 _8q2 = 8.0f * q2;
_seminahn 0:4ff8aeb3e4d1 210 q0q0 = q0 * q0;
_seminahn 0:4ff8aeb3e4d1 211 q1q1 = q1 * q1;
_seminahn 0:4ff8aeb3e4d1 212 q2q2 = q2 * q2;
_seminahn 0:4ff8aeb3e4d1 213 q3q3 = q3 * q3;
_seminahn 0:4ff8aeb3e4d1 214
_seminahn 0:4ff8aeb3e4d1 215 // Gradient decent algorithm corrective step
_seminahn 0:4ff8aeb3e4d1 216 s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
_seminahn 0:4ff8aeb3e4d1 217 s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
_seminahn 0:4ff8aeb3e4d1 218 s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
_seminahn 0:4ff8aeb3e4d1 219 s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;
_seminahn 0:4ff8aeb3e4d1 220
_seminahn 0:4ff8aeb3e4d1 221 recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
_seminahn 0:4ff8aeb3e4d1 222 //pc.printf("nomalized step: %.5f\n\r",recipNorm);
_seminahn 0:4ff8aeb3e4d1 223 s0 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 224 s1 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 225 s2 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 226 s3 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 227 //pc.printf("%.5f %.5f %.5f %.5f ",s0,s1,s2,s3);
_seminahn 0:4ff8aeb3e4d1 228 // Apply feedback step
_seminahn 0:4ff8aeb3e4d1 229 qDot1 -= beta * s0;
_seminahn 0:4ff8aeb3e4d1 230 qDot2 -= beta * s1;
_seminahn 0:4ff8aeb3e4d1 231 qDot3 -= beta * s2;
_seminahn 0:4ff8aeb3e4d1 232 qDot4 -= beta * s3;
_seminahn 0:4ff8aeb3e4d1 233 //pc.printf("%.5f %.5f %.5f %.5f ",qDot1,qDot2,qDot3,qDot4);
_seminahn 0:4ff8aeb3e4d1 234 //pc.printf("\n\r---------------------------------------------------------------------------\n\r");
_seminahn 0:4ff8aeb3e4d1 235 }
_seminahn 0:4ff8aeb3e4d1 236
_seminahn 0:4ff8aeb3e4d1 237 // Integrate rate of change of quaternion to yield quaternion
_seminahn 0:4ff8aeb3e4d1 238 q0 += qDot1 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 239 q1 += qDot2 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 240 q2 += qDot3 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 241 q3 += qDot4 * invSampleFreq;
_seminahn 0:4ff8aeb3e4d1 242 //pc.printf("\n\rinvSampleFreq: %.5f\n\r",invSampleFreq);
_seminahn 0:4ff8aeb3e4d1 243 // Normalise quaternion
_seminahn 0:4ff8aeb3e4d1 244 recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
_seminahn 0:4ff8aeb3e4d1 245 q0 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 246 q1 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 247 q2 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 248 q3 *= recipNorm;
_seminahn 0:4ff8aeb3e4d1 249 //pc.printf("nomalized quaternion: %.5f\n\r",recipNorm);
_seminahn 0:4ff8aeb3e4d1 250 anglesComputed = 0;
_seminahn 0:4ff8aeb3e4d1 251 }
_seminahn 0:4ff8aeb3e4d1 252
_seminahn 0:4ff8aeb3e4d1 253 //-------------------------------------------------------------------------------------------
_seminahn 0:4ff8aeb3e4d1 254 // Fast inverse square-root
_seminahn 0:4ff8aeb3e4d1 255 // See: http://en.wikipedia.org/wiki/Fast_inverse_square_root
_seminahn 0:4ff8aeb3e4d1 256
_seminahn 0:4ff8aeb3e4d1 257 float Madgwick::invSqrt(float x) {
_seminahn 0:4ff8aeb3e4d1 258 float halfx = 0.5f * x;
_seminahn 0:4ff8aeb3e4d1 259 float y = x;
_seminahn 0:4ff8aeb3e4d1 260 long i = *(long*)&y;
_seminahn 0:4ff8aeb3e4d1 261 i = 0x5f3759df - (i>>1);
_seminahn 0:4ff8aeb3e4d1 262 y = *(float*)&i;
_seminahn 0:4ff8aeb3e4d1 263 y = y * (1.5f - (halfx * y * y));
_seminahn 0:4ff8aeb3e4d1 264 y = y * (1.5f - (halfx * y * y));
_seminahn 0:4ff8aeb3e4d1 265 return y;
_seminahn 0:4ff8aeb3e4d1 266 }
_seminahn 0:4ff8aeb3e4d1 267
_seminahn 0:4ff8aeb3e4d1 268 //-------------------------------------------------------------------------------------------
_seminahn 0:4ff8aeb3e4d1 269
_seminahn 0:4ff8aeb3e4d1 270 void Madgwick::computeAngles()
_seminahn 0:4ff8aeb3e4d1 271 {
_seminahn 0:4ff8aeb3e4d1 272 roll = atan2f(q0*q1 + q2*q3, 0.5f - q1*q1 - q2*q2);
_seminahn 0:4ff8aeb3e4d1 273 pitch = asinf(-2.0f * (q1*q3 - q0*q2));
_seminahn 0:4ff8aeb3e4d1 274 yaw = atan2f(q1*q2 + q0*q3, 0.5f - q2*q2 - q3*q3);
_seminahn 0:4ff8aeb3e4d1 275 anglesComputed = 1;
_seminahn 0:4ff8aeb3e4d1 276 }
_seminahn 0:4ff8aeb3e4d1 277
_seminahn 0:4ff8aeb3e4d1 278