KPC / MadgwickAHRS

MadgwickAHRS

Dependents:   Pmod_NAV

MadgwickAHRS.cpp@0:0f88b99a97ce, 2019-04-25 (annotated)

Committer:
771_8bit
Date:
Thu Apr 25 04:03:54 2019 +0000
Revision:
0:0f88b99a97ce
hello;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
771_8bit 0:0f88b99a97ce 1 //=============================================================================================
771_8bit 0:0f88b99a97ce 2 // MadgwickAHRS.c
771_8bit 0:0f88b99a97ce 3 //=============================================================================================
771_8bit 0:0f88b99a97ce 4 //
771_8bit 0:0f88b99a97ce 5 // Implementation of Madgwick's IMU and AHRS algorithms.
771_8bit 0:0f88b99a97ce 6 // See: http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/
771_8bit 0:0f88b99a97ce 7 //
771_8bit 0:0f88b99a97ce 8 // From the x-io website "Open-source resources available on this website are
771_8bit 0:0f88b99a97ce 9 // provided under the GNU General Public Licence unless an alternative licence
771_8bit 0:0f88b99a97ce 10 // is provided in source."
771_8bit 0:0f88b99a97ce 11 //
771_8bit 0:0f88b99a97ce 12 // Date Author Notes
771_8bit 0:0f88b99a97ce 13 // 29/09/2011 SOH Madgwick Initial release
771_8bit 0:0f88b99a97ce 14 // 02/10/2011 SOH Madgwick Optimised for reduced CPU load
771_8bit 0:0f88b99a97ce 15 // 19/02/2012 SOH Madgwick Magnetometer measurement is normalised
771_8bit 0:0f88b99a97ce 16 // 18/12/2016 Added better fast inverse square root
771_8bit 0:0f88b99a97ce 17 //
771_8bit 0:0f88b99a97ce 18 //=============================================================================================
771_8bit 0:0f88b99a97ce 19
771_8bit 0:0f88b99a97ce 20 //-------------------------------------------------------------------------------------------
771_8bit 0:0f88b99a97ce 21 // Header files
771_8bit 0:0f88b99a97ce 22
771_8bit 0:0f88b99a97ce 23 #include "MadgwickAHRS.h"
771_8bit 0:0f88b99a97ce 24 #include <math.h>
771_8bit 0:0f88b99a97ce 25
771_8bit 0:0f88b99a97ce 26 //-------------------------------------------------------------------------------------------
771_8bit 0:0f88b99a97ce 27 // Definitions
771_8bit 0:0f88b99a97ce 28
771_8bit 0:0f88b99a97ce 29 #define sampleFreqDef 500.0f // sample frequency in Hz
771_8bit 0:0f88b99a97ce 30 #define betaDef 0.1f // 2 * proportional gain 0.1 - 0.5 - 5
771_8bit 0:0f88b99a97ce 31
771_8bit 0:0f88b99a97ce 32
771_8bit 0:0f88b99a97ce 33 //============================================================================================
771_8bit 0:0f88b99a97ce 34 // Functions
771_8bit 0:0f88b99a97ce 35
771_8bit 0:0f88b99a97ce 36 //-------------------------------------------------------------------------------------------
771_8bit 0:0f88b99a97ce 37 // AHRS algorithm update
771_8bit 0:0f88b99a97ce 38
771_8bit 0:0f88b99a97ce 39 Madgwick::Madgwick() {
771_8bit 0:0f88b99a97ce 40 beta = betaDef;
771_8bit 0:0f88b99a97ce 41 q0 = 1.0f;
771_8bit 0:0f88b99a97ce 42 q1 = 0.0f;
771_8bit 0:0f88b99a97ce 43 q2 = 0.0f;
771_8bit 0:0f88b99a97ce 44 q3 = 0.0f;
771_8bit 0:0f88b99a97ce 45 invSampleFreq = 1.0f / sampleFreqDef;
771_8bit 0:0f88b99a97ce 46 anglesComputed = 0;
771_8bit 0:0f88b99a97ce 47 }
771_8bit 0:0f88b99a97ce 48
771_8bit 0:0f88b99a97ce 49 void Madgwick::update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) {
771_8bit 0:0f88b99a97ce 50 float recipNorm;
771_8bit 0:0f88b99a97ce 51 float s0, s1, s2, s3;
771_8bit 0:0f88b99a97ce 52 float qDot1, qDot2, qDot3, qDot4;
771_8bit 0:0f88b99a97ce 53 float hx, hy;
771_8bit 0:0f88b99a97ce 54 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;
771_8bit 0:0f88b99a97ce 55
771_8bit 0:0f88b99a97ce 56 // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)
771_8bit 0:0f88b99a97ce 57 if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
771_8bit 0:0f88b99a97ce 58 updateIMU(gx, gy, gz, ax, ay, az);
771_8bit 0:0f88b99a97ce 59 return;
771_8bit 0:0f88b99a97ce 60 }
771_8bit 0:0f88b99a97ce 61
771_8bit 0:0f88b99a97ce 62 // Convert gyroscope degrees/sec to radians/sec
771_8bit 0:0f88b99a97ce 63 gx *= 0.0174533f;
771_8bit 0:0f88b99a97ce 64 gy *= 0.0174533f;
771_8bit 0:0f88b99a97ce 65 gz *= 0.0174533f;
771_8bit 0:0f88b99a97ce 66
771_8bit 0:0f88b99a97ce 67 // Rate of change of quaternion from gyroscope
771_8bit 0:0f88b99a97ce 68 qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
771_8bit 0:0f88b99a97ce 69 qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
771_8bit 0:0f88b99a97ce 70 qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
771_8bit 0:0f88b99a97ce 71 qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
771_8bit 0:0f88b99a97ce 72
771_8bit 0:0f88b99a97ce 73 // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
771_8bit 0:0f88b99a97ce 74 if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
771_8bit 0:0f88b99a97ce 75
771_8bit 0:0f88b99a97ce 76 // Normalise accelerometer measurement
771_8bit 0:0f88b99a97ce 77 recipNorm = invSqrt(ax * ax + ay * ay + az * az);
771_8bit 0:0f88b99a97ce 78 ax *= recipNorm;
771_8bit 0:0f88b99a97ce 79 ay *= recipNorm;
771_8bit 0:0f88b99a97ce 80 az *= recipNorm;
771_8bit 0:0f88b99a97ce 81
771_8bit 0:0f88b99a97ce 82 // Normalise magnetometer measurement
771_8bit 0:0f88b99a97ce 83 recipNorm = invSqrt(mx * mx + my * my + mz * mz);
771_8bit 0:0f88b99a97ce 84 mx *= recipNorm;
771_8bit 0:0f88b99a97ce 85 my *= recipNorm;
771_8bit 0:0f88b99a97ce 86 mz *= recipNorm;
771_8bit 0:0f88b99a97ce 87
771_8bit 0:0f88b99a97ce 88 // Auxiliary variables to avoid repeated arithmetic
771_8bit 0:0f88b99a97ce 89 _2q0mx = 2.0f * q0 * mx;
771_8bit 0:0f88b99a97ce 90 _2q0my = 2.0f * q0 * my;
771_8bit 0:0f88b99a97ce 91 _2q0mz = 2.0f * q0 * mz;
771_8bit 0:0f88b99a97ce 92 _2q1mx = 2.0f * q1 * mx;
771_8bit 0:0f88b99a97ce 93 _2q0 = 2.0f * q0;
771_8bit 0:0f88b99a97ce 94 _2q1 = 2.0f * q1;
771_8bit 0:0f88b99a97ce 95 _2q2 = 2.0f * q2;
771_8bit 0:0f88b99a97ce 96 _2q3 = 2.0f * q3;
771_8bit 0:0f88b99a97ce 97 _2q0q2 = 2.0f * q0 * q2;
771_8bit 0:0f88b99a97ce 98 _2q2q3 = 2.0f * q2 * q3;
771_8bit 0:0f88b99a97ce 99 q0q0 = q0 * q0;
771_8bit 0:0f88b99a97ce 100 q0q1 = q0 * q1;
771_8bit 0:0f88b99a97ce 101 q0q2 = q0 * q2;
771_8bit 0:0f88b99a97ce 102 q0q3 = q0 * q3;
771_8bit 0:0f88b99a97ce 103 q1q1 = q1 * q1;
771_8bit 0:0f88b99a97ce 104 q1q2 = q1 * q2;
771_8bit 0:0f88b99a97ce 105 q1q3 = q1 * q3;
771_8bit 0:0f88b99a97ce 106 q2q2 = q2 * q2;
771_8bit 0:0f88b99a97ce 107 q2q3 = q2 * q3;
771_8bit 0:0f88b99a97ce 108 q3q3 = q3 * q3;
771_8bit 0:0f88b99a97ce 109
771_8bit 0:0f88b99a97ce 110 // Reference direction of Earth's magnetic field
771_8bit 0:0f88b99a97ce 111 hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;
771_8bit 0:0f88b99a97ce 112 hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;
771_8bit 0:0f88b99a97ce 113 _2bx = sqrtf(hx * hx + hy * hy);
771_8bit 0:0f88b99a97ce 114 _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;
771_8bit 0:0f88b99a97ce 115 _4bx = 2.0f * _2bx;
771_8bit 0:0f88b99a97ce 116 _4bz = 2.0f * _2bz;
771_8bit 0:0f88b99a97ce 117
771_8bit 0:0f88b99a97ce 118 // Gradient decent algorithm corrective step
771_8bit 0:0f88b99a97ce 119 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);
771_8bit 0:0f88b99a97ce 120 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);
771_8bit 0:0f88b99a97ce 121 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);
771_8bit 0:0f88b99a97ce 122 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);
771_8bit 0:0f88b99a97ce 123 recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
771_8bit 0:0f88b99a97ce 124 s0 *= recipNorm;
771_8bit 0:0f88b99a97ce 125 s1 *= recipNorm;
771_8bit 0:0f88b99a97ce 126 s2 *= recipNorm;
771_8bit 0:0f88b99a97ce 127 s3 *= recipNorm;
771_8bit 0:0f88b99a97ce 128
771_8bit 0:0f88b99a97ce 129 // Apply feedback step
771_8bit 0:0f88b99a97ce 130 qDot1 -= beta * s0;
771_8bit 0:0f88b99a97ce 131 qDot2 -= beta * s1;
771_8bit 0:0f88b99a97ce 132 qDot3 -= beta * s2;
771_8bit 0:0f88b99a97ce 133 qDot4 -= beta * s3;
771_8bit 0:0f88b99a97ce 134 }
771_8bit 0:0f88b99a97ce 135
771_8bit 0:0f88b99a97ce 136 // Integrate rate of change of quaternion to yield quaternion
771_8bit 0:0f88b99a97ce 137 q0 += qDot1 * invSampleFreq;
771_8bit 0:0f88b99a97ce 138 q1 += qDot2 * invSampleFreq;
771_8bit 0:0f88b99a97ce 139 q2 += qDot3 * invSampleFreq;
771_8bit 0:0f88b99a97ce 140 q3 += qDot4 * invSampleFreq;
771_8bit 0:0f88b99a97ce 141
771_8bit 0:0f88b99a97ce 142 // Normalise quaternion
771_8bit 0:0f88b99a97ce 143 recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
771_8bit 0:0f88b99a97ce 144 q0 *= recipNorm;
771_8bit 0:0f88b99a97ce 145 q1 *= recipNorm;
771_8bit 0:0f88b99a97ce 146 q2 *= recipNorm;
771_8bit 0:0f88b99a97ce 147 q3 *= recipNorm;
771_8bit 0:0f88b99a97ce 148 anglesComputed = 0;
771_8bit 0:0f88b99a97ce 149 }
771_8bit 0:0f88b99a97ce 150
771_8bit 0:0f88b99a97ce 151 //-------------------------------------------------------------------------------------------
771_8bit 0:0f88b99a97ce 152 // IMU algorithm update
771_8bit 0:0f88b99a97ce 153
771_8bit 0:0f88b99a97ce 154 void Madgwick::updateIMU(float gx, float gy, float gz, float ax, float ay, float az) {
771_8bit 0:0f88b99a97ce 155 float recipNorm;
771_8bit 0:0f88b99a97ce 156 float s0, s1, s2, s3;
771_8bit 0:0f88b99a97ce 157 float qDot1, qDot2, qDot3, qDot4;
771_8bit 0:0f88b99a97ce 158 float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;
771_8bit 0:0f88b99a97ce 159
771_8bit 0:0f88b99a97ce 160 // Convert gyroscope degrees/sec to radians/sec
771_8bit 0:0f88b99a97ce 161 gx *= 0.0174533f;
771_8bit 0:0f88b99a97ce 162 gy *= 0.0174533f;
771_8bit 0:0f88b99a97ce 163 gz *= 0.0174533f;
771_8bit 0:0f88b99a97ce 164
771_8bit 0:0f88b99a97ce 165 // Rate of change of quaternion from gyroscope
771_8bit 0:0f88b99a97ce 166 qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
771_8bit 0:0f88b99a97ce 167 qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
771_8bit 0:0f88b99a97ce 168 qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
771_8bit 0:0f88b99a97ce 169 qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
771_8bit 0:0f88b99a97ce 170
771_8bit 0:0f88b99a97ce 171 // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
771_8bit 0:0f88b99a97ce 172 if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
771_8bit 0:0f88b99a97ce 173
771_8bit 0:0f88b99a97ce 174 // Normalise accelerometer measurement
771_8bit 0:0f88b99a97ce 175 recipNorm = invSqrt(ax * ax + ay * ay + az * az);
771_8bit 0:0f88b99a97ce 176 ax *= recipNorm;
771_8bit 0:0f88b99a97ce 177 ay *= recipNorm;
771_8bit 0:0f88b99a97ce 178 az *= recipNorm;
771_8bit 0:0f88b99a97ce 179
771_8bit 0:0f88b99a97ce 180 // Auxiliary variables to avoid repeated arithmetic
771_8bit 0:0f88b99a97ce 181 _2q0 = 2.0f * q0;
771_8bit 0:0f88b99a97ce 182 _2q1 = 2.0f * q1;
771_8bit 0:0f88b99a97ce 183 _2q2 = 2.0f * q2;
771_8bit 0:0f88b99a97ce 184 _2q3 = 2.0f * q3;
771_8bit 0:0f88b99a97ce 185 _4q0 = 4.0f * q0;
771_8bit 0:0f88b99a97ce 186 _4q1 = 4.0f * q1;
771_8bit 0:0f88b99a97ce 187 _4q2 = 4.0f * q2;
771_8bit 0:0f88b99a97ce 188 _8q1 = 8.0f * q1;
771_8bit 0:0f88b99a97ce 189 _8q2 = 8.0f * q2;
771_8bit 0:0f88b99a97ce 190 q0q0 = q0 * q0;
771_8bit 0:0f88b99a97ce 191 q1q1 = q1 * q1;
771_8bit 0:0f88b99a97ce 192 q2q2 = q2 * q2;
771_8bit 0:0f88b99a97ce 193 q3q3 = q3 * q3;
771_8bit 0:0f88b99a97ce 194
771_8bit 0:0f88b99a97ce 195 // Gradient decent algorithm corrective step
771_8bit 0:0f88b99a97ce 196 s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
771_8bit 0:0f88b99a97ce 197 s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
771_8bit 0:0f88b99a97ce 198 s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
771_8bit 0:0f88b99a97ce 199 s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;
771_8bit 0:0f88b99a97ce 200 recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
771_8bit 0:0f88b99a97ce 201 s0 *= recipNorm;
771_8bit 0:0f88b99a97ce 202 s1 *= recipNorm;
771_8bit 0:0f88b99a97ce 203 s2 *= recipNorm;
771_8bit 0:0f88b99a97ce 204 s3 *= recipNorm;
771_8bit 0:0f88b99a97ce 205
771_8bit 0:0f88b99a97ce 206 // Apply feedback step
771_8bit 0:0f88b99a97ce 207 qDot1 -= beta * s0;
771_8bit 0:0f88b99a97ce 208 qDot2 -= beta * s1;
771_8bit 0:0f88b99a97ce 209 qDot3 -= beta * s2;
771_8bit 0:0f88b99a97ce 210 qDot4 -= beta * s3;
771_8bit 0:0f88b99a97ce 211 }
771_8bit 0:0f88b99a97ce 212
771_8bit 0:0f88b99a97ce 213 // Integrate rate of change of quaternion to yield quaternion
771_8bit 0:0f88b99a97ce 214 q0 += qDot1 * invSampleFreq;
771_8bit 0:0f88b99a97ce 215 q1 += qDot2 * invSampleFreq;
771_8bit 0:0f88b99a97ce 216 q2 += qDot3 * invSampleFreq;
771_8bit 0:0f88b99a97ce 217 q3 += qDot4 * invSampleFreq;
771_8bit 0:0f88b99a97ce 218
771_8bit 0:0f88b99a97ce 219 // Normalise quaternion
771_8bit 0:0f88b99a97ce 220 recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
771_8bit 0:0f88b99a97ce 221 q0 *= recipNorm;
771_8bit 0:0f88b99a97ce 222 q1 *= recipNorm;
771_8bit 0:0f88b99a97ce 223 q2 *= recipNorm;
771_8bit 0:0f88b99a97ce 224 q3 *= recipNorm;
771_8bit 0:0f88b99a97ce 225 anglesComputed = 0;
771_8bit 0:0f88b99a97ce 226 }
771_8bit 0:0f88b99a97ce 227
771_8bit 0:0f88b99a97ce 228 //-------------------------------------------------------------------------------------------
771_8bit 0:0f88b99a97ce 229 // Fast inverse square-root
771_8bit 0:0f88b99a97ce 230 // See: http://en.wikipedia.org/wiki/Fast_inverse_square_root
771_8bit 0:0f88b99a97ce 231
771_8bit 0:0f88b99a97ce 232 /*float Madgwick::invSqrt(float x) {
771_8bit 0:0f88b99a97ce 233 float halfx = 0.5f * x;
771_8bit 0:0f88b99a97ce 234 float y = x;
771_8bit 0:0f88b99a97ce 235 long i = *(long*)&y;
771_8bit 0:0f88b99a97ce 236 i = 0x5f3759df - (i>>1);
771_8bit 0:0f88b99a97ce 237 y = *(float*)&i;
771_8bit 0:0f88b99a97ce 238 y = y * (1.5f - (halfx * y * y));
771_8bit 0:0f88b99a97ce 239 y = y * (1.5f - (halfx * y * y));
771_8bit 0:0f88b99a97ce 240 return y;
771_8bit 0:0f88b99a97ce 241 } */
771_8bit 0:0f88b99a97ce 242
771_8bit 0:0f88b99a97ce 243 float Madgwick::invSqrt(float x){
771_8bit 0:0f88b99a97ce 244 unsigned int i = 0x5F1F1412 - (*(unsigned int*)&x >> 1);
771_8bit 0:0f88b99a97ce 245 float tmp = *(float*)&i;
771_8bit 0:0f88b99a97ce 246 return tmp * (1.69000231f - 0.714158168f * x * tmp * tmp);
771_8bit 0:0f88b99a97ce 247 }
771_8bit 0:0f88b99a97ce 248
771_8bit 0:0f88b99a97ce 249 //-------------------------------------------------------------------------------------------
771_8bit 0:0f88b99a97ce 250
771_8bit 0:0f88b99a97ce 251 void Madgwick::computeAngles()
771_8bit 0:0f88b99a97ce 252 {
771_8bit 0:0f88b99a97ce 253 roll = atan2f(q0*q1 + q2*q3, 0.5f - q1*q1 - q2*q2);
771_8bit 0:0f88b99a97ce 254 pitch = asinf(-2.0f * (q1*q3 - q0*q2));
771_8bit 0:0f88b99a97ce 255 yaw = atan2f(q1*q2 + q0*q3, 0.5f - q2*q2 - q3*q3);
771_8bit 0:0f88b99a97ce 256 anglesComputed = 1;
771_8bit 0:0f88b99a97ce 257 }