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MadgwickAHRS.cpp@0:c32a5fb80d4d, 2018-12-11 (annotated)
- Committer:
- Yukina
- Date:
- Tue Dec 11 13:59:10 2018 +0000
- Revision:
- 0:c32a5fb80d4d
Madgwick Filter
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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Yukina | 0:c32a5fb80d4d | 1 | //============================================================================================= |
Yukina | 0:c32a5fb80d4d | 2 | // MadgwickAHRS.c |
Yukina | 0:c32a5fb80d4d | 3 | //============================================================================================= |
Yukina | 0:c32a5fb80d4d | 4 | // |
Yukina | 0:c32a5fb80d4d | 5 | // Implementation of Madgwick's IMU and AHRS algorithms. |
Yukina | 0:c32a5fb80d4d | 6 | // See: http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/ |
Yukina | 0:c32a5fb80d4d | 7 | // |
Yukina | 0:c32a5fb80d4d | 8 | // From the x-io website "Open-source resources available on this website are |
Yukina | 0:c32a5fb80d4d | 9 | // provided under the GNU General Public Licence unless an alternative licence |
Yukina | 0:c32a5fb80d4d | 10 | // is provided in source." |
Yukina | 0:c32a5fb80d4d | 11 | // |
Yukina | 0:c32a5fb80d4d | 12 | // Date Author Notes |
Yukina | 0:c32a5fb80d4d | 13 | // 29/09/2011 SOH Madgwick Initial release |
Yukina | 0:c32a5fb80d4d | 14 | // 02/10/2011 SOH Madgwick Optimised for reduced CPU load |
Yukina | 0:c32a5fb80d4d | 15 | // 19/02/2012 SOH Madgwick Magnetometer measurement is normalised |
Yukina | 0:c32a5fb80d4d | 16 | // |
Yukina | 0:c32a5fb80d4d | 17 | //============================================================================================= |
Yukina | 0:c32a5fb80d4d | 18 | |
Yukina | 0:c32a5fb80d4d | 19 | //------------------------------------------------------------------------------------------- |
Yukina | 0:c32a5fb80d4d | 20 | // Header files |
Yukina | 0:c32a5fb80d4d | 21 | |
Yukina | 0:c32a5fb80d4d | 22 | #include "MadgwickAHRS.h" |
Yukina | 0:c32a5fb80d4d | 23 | #include <math.h> |
Yukina | 0:c32a5fb80d4d | 24 | |
Yukina | 0:c32a5fb80d4d | 25 | //------------------------------------------------------------------------------------------- |
Yukina | 0:c32a5fb80d4d | 26 | // Definitions |
Yukina | 0:c32a5fb80d4d | 27 | |
Yukina | 0:c32a5fb80d4d | 28 | #define sampleFreqDef 512.0f // sample frequency in Hz |
Yukina | 0:c32a5fb80d4d | 29 | #define betaDef 0.1f // 2 * proportional gain |
Yukina | 0:c32a5fb80d4d | 30 | |
Yukina | 0:c32a5fb80d4d | 31 | |
Yukina | 0:c32a5fb80d4d | 32 | //============================================================================================ |
Yukina | 0:c32a5fb80d4d | 33 | // Functions |
Yukina | 0:c32a5fb80d4d | 34 | |
Yukina | 0:c32a5fb80d4d | 35 | //------------------------------------------------------------------------------------------- |
Yukina | 0:c32a5fb80d4d | 36 | // AHRS algorithm update |
Yukina | 0:c32a5fb80d4d | 37 | |
Yukina | 0:c32a5fb80d4d | 38 | Madgwick::Madgwick() { |
Yukina | 0:c32a5fb80d4d | 39 | beta = betaDef; |
Yukina | 0:c32a5fb80d4d | 40 | q0 = 1.0f; |
Yukina | 0:c32a5fb80d4d | 41 | q1 = 0.0f; |
Yukina | 0:c32a5fb80d4d | 42 | q2 = 0.0f; |
Yukina | 0:c32a5fb80d4d | 43 | q3 = 0.0f; |
Yukina | 0:c32a5fb80d4d | 44 | invSampleFreq = 1.0f / sampleFreqDef; |
Yukina | 0:c32a5fb80d4d | 45 | anglesComputed = 0; |
Yukina | 0:c32a5fb80d4d | 46 | } |
Yukina | 0:c32a5fb80d4d | 47 | |
Yukina | 0:c32a5fb80d4d | 48 | void Madgwick::update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) { |
Yukina | 0:c32a5fb80d4d | 49 | float recipNorm; |
Yukina | 0:c32a5fb80d4d | 50 | float s0, s1, s2, s3; |
Yukina | 0:c32a5fb80d4d | 51 | float qDot1, qDot2, qDot3, qDot4; |
Yukina | 0:c32a5fb80d4d | 52 | float hx, hy; |
Yukina | 0:c32a5fb80d4d | 53 | 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; |
Yukina | 0:c32a5fb80d4d | 54 | |
Yukina | 0:c32a5fb80d4d | 55 | // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation) |
Yukina | 0:c32a5fb80d4d | 56 | if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) { |
Yukina | 0:c32a5fb80d4d | 57 | updateIMU(gx, gy, gz, ax, ay, az); |
Yukina | 0:c32a5fb80d4d | 58 | return; |
Yukina | 0:c32a5fb80d4d | 59 | } |
Yukina | 0:c32a5fb80d4d | 60 | |
Yukina | 0:c32a5fb80d4d | 61 | // Convert gyroscope degrees/sec to radians/sec |
Yukina | 0:c32a5fb80d4d | 62 | gx *= 0.0174533f; |
Yukina | 0:c32a5fb80d4d | 63 | gy *= 0.0174533f; |
Yukina | 0:c32a5fb80d4d | 64 | gz *= 0.0174533f; |
Yukina | 0:c32a5fb80d4d | 65 | |
Yukina | 0:c32a5fb80d4d | 66 | // Rate of change of quaternion from gyroscope |
Yukina | 0:c32a5fb80d4d | 67 | qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz); |
Yukina | 0:c32a5fb80d4d | 68 | qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy); |
Yukina | 0:c32a5fb80d4d | 69 | qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx); |
Yukina | 0:c32a5fb80d4d | 70 | qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx); |
Yukina | 0:c32a5fb80d4d | 71 | |
Yukina | 0:c32a5fb80d4d | 72 | // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation) |
Yukina | 0:c32a5fb80d4d | 73 | if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) { |
Yukina | 0:c32a5fb80d4d | 74 | |
Yukina | 0:c32a5fb80d4d | 75 | // Normalise accelerometer measurement |
Yukina | 0:c32a5fb80d4d | 76 | recipNorm = invSqrt(ax * ax + ay * ay + az * az); |
Yukina | 0:c32a5fb80d4d | 77 | ax *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 78 | ay *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 79 | az *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 80 | |
Yukina | 0:c32a5fb80d4d | 81 | // Normalise magnetometer measurement |
Yukina | 0:c32a5fb80d4d | 82 | recipNorm = invSqrt(mx * mx + my * my + mz * mz); |
Yukina | 0:c32a5fb80d4d | 83 | mx *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 84 | my *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 85 | mz *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 86 | |
Yukina | 0:c32a5fb80d4d | 87 | // Auxiliary variables to avoid repeated arithmetic |
Yukina | 0:c32a5fb80d4d | 88 | _2q0mx = 2.0f * q0 * mx; |
Yukina | 0:c32a5fb80d4d | 89 | _2q0my = 2.0f * q0 * my; |
Yukina | 0:c32a5fb80d4d | 90 | _2q0mz = 2.0f * q0 * mz; |
Yukina | 0:c32a5fb80d4d | 91 | _2q1mx = 2.0f * q1 * mx; |
Yukina | 0:c32a5fb80d4d | 92 | _2q0 = 2.0f * q0; |
Yukina | 0:c32a5fb80d4d | 93 | _2q1 = 2.0f * q1; |
Yukina | 0:c32a5fb80d4d | 94 | _2q2 = 2.0f * q2; |
Yukina | 0:c32a5fb80d4d | 95 | _2q3 = 2.0f * q3; |
Yukina | 0:c32a5fb80d4d | 96 | _2q0q2 = 2.0f * q0 * q2; |
Yukina | 0:c32a5fb80d4d | 97 | _2q2q3 = 2.0f * q2 * q3; |
Yukina | 0:c32a5fb80d4d | 98 | q0q0 = q0 * q0; |
Yukina | 0:c32a5fb80d4d | 99 | q0q1 = q0 * q1; |
Yukina | 0:c32a5fb80d4d | 100 | q0q2 = q0 * q2; |
Yukina | 0:c32a5fb80d4d | 101 | q0q3 = q0 * q3; |
Yukina | 0:c32a5fb80d4d | 102 | q1q1 = q1 * q1; |
Yukina | 0:c32a5fb80d4d | 103 | q1q2 = q1 * q2; |
Yukina | 0:c32a5fb80d4d | 104 | q1q3 = q1 * q3; |
Yukina | 0:c32a5fb80d4d | 105 | q2q2 = q2 * q2; |
Yukina | 0:c32a5fb80d4d | 106 | q2q3 = q2 * q3; |
Yukina | 0:c32a5fb80d4d | 107 | q3q3 = q3 * q3; |
Yukina | 0:c32a5fb80d4d | 108 | |
Yukina | 0:c32a5fb80d4d | 109 | // Reference direction of Earth's magnetic field |
Yukina | 0:c32a5fb80d4d | 110 | hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3; |
Yukina | 0:c32a5fb80d4d | 111 | hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3; |
Yukina | 0:c32a5fb80d4d | 112 | _2bx = sqrtf(hx * hx + hy * hy); |
Yukina | 0:c32a5fb80d4d | 113 | _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3; |
Yukina | 0:c32a5fb80d4d | 114 | _4bx = 2.0f * _2bx; |
Yukina | 0:c32a5fb80d4d | 115 | _4bz = 2.0f * _2bz; |
Yukina | 0:c32a5fb80d4d | 116 | |
Yukina | 0:c32a5fb80d4d | 117 | // Gradient decent algorithm corrective step |
Yukina | 0:c32a5fb80d4d | 118 | 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); |
Yukina | 0:c32a5fb80d4d | 119 | 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); |
Yukina | 0:c32a5fb80d4d | 120 | 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); |
Yukina | 0:c32a5fb80d4d | 121 | 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); |
Yukina | 0:c32a5fb80d4d | 122 | recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude |
Yukina | 0:c32a5fb80d4d | 123 | s0 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 124 | s1 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 125 | s2 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 126 | s3 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 127 | |
Yukina | 0:c32a5fb80d4d | 128 | // Apply feedback step |
Yukina | 0:c32a5fb80d4d | 129 | qDot1 -= beta * s0; |
Yukina | 0:c32a5fb80d4d | 130 | qDot2 -= beta * s1; |
Yukina | 0:c32a5fb80d4d | 131 | qDot3 -= beta * s2; |
Yukina | 0:c32a5fb80d4d | 132 | qDot4 -= beta * s3; |
Yukina | 0:c32a5fb80d4d | 133 | } |
Yukina | 0:c32a5fb80d4d | 134 | |
Yukina | 0:c32a5fb80d4d | 135 | // Integrate rate of change of quaternion to yield quaternion |
Yukina | 0:c32a5fb80d4d | 136 | q0 += qDot1 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 137 | q1 += qDot2 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 138 | q2 += qDot3 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 139 | q3 += qDot4 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 140 | |
Yukina | 0:c32a5fb80d4d | 141 | // Normalise quaternion |
Yukina | 0:c32a5fb80d4d | 142 | recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3); |
Yukina | 0:c32a5fb80d4d | 143 | q0 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 144 | q1 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 145 | q2 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 146 | q3 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 147 | anglesComputed = 0; |
Yukina | 0:c32a5fb80d4d | 148 | } |
Yukina | 0:c32a5fb80d4d | 149 | |
Yukina | 0:c32a5fb80d4d | 150 | //------------------------------------------------------------------------------------------- |
Yukina | 0:c32a5fb80d4d | 151 | // IMU algorithm update |
Yukina | 0:c32a5fb80d4d | 152 | |
Yukina | 0:c32a5fb80d4d | 153 | void Madgwick::updateIMU(float gx, float gy, float gz, float ax, float ay, float az) { |
Yukina | 0:c32a5fb80d4d | 154 | float recipNorm; |
Yukina | 0:c32a5fb80d4d | 155 | float s0, s1, s2, s3; |
Yukina | 0:c32a5fb80d4d | 156 | float qDot1, qDot2, qDot3, qDot4; |
Yukina | 0:c32a5fb80d4d | 157 | float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3; |
Yukina | 0:c32a5fb80d4d | 158 | |
Yukina | 0:c32a5fb80d4d | 159 | // Convert gyroscope degrees/sec to radians/sec |
Yukina | 0:c32a5fb80d4d | 160 | gx *= 0.0174533f; |
Yukina | 0:c32a5fb80d4d | 161 | gy *= 0.0174533f; |
Yukina | 0:c32a5fb80d4d | 162 | gz *= 0.0174533f; |
Yukina | 0:c32a5fb80d4d | 163 | |
Yukina | 0:c32a5fb80d4d | 164 | // Rate of change of quaternion from gyroscope |
Yukina | 0:c32a5fb80d4d | 165 | qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz); |
Yukina | 0:c32a5fb80d4d | 166 | qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy); |
Yukina | 0:c32a5fb80d4d | 167 | qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx); |
Yukina | 0:c32a5fb80d4d | 168 | qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx); |
Yukina | 0:c32a5fb80d4d | 169 | |
Yukina | 0:c32a5fb80d4d | 170 | // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation) |
Yukina | 0:c32a5fb80d4d | 171 | if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) { |
Yukina | 0:c32a5fb80d4d | 172 | |
Yukina | 0:c32a5fb80d4d | 173 | // Normalise accelerometer measurement |
Yukina | 0:c32a5fb80d4d | 174 | recipNorm = invSqrt(ax * ax + ay * ay + az * az); |
Yukina | 0:c32a5fb80d4d | 175 | ax *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 176 | ay *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 177 | az *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 178 | |
Yukina | 0:c32a5fb80d4d | 179 | // Auxiliary variables to avoid repeated arithmetic |
Yukina | 0:c32a5fb80d4d | 180 | _2q0 = 2.0f * q0; |
Yukina | 0:c32a5fb80d4d | 181 | _2q1 = 2.0f * q1; |
Yukina | 0:c32a5fb80d4d | 182 | _2q2 = 2.0f * q2; |
Yukina | 0:c32a5fb80d4d | 183 | _2q3 = 2.0f * q3; |
Yukina | 0:c32a5fb80d4d | 184 | _4q0 = 4.0f * q0; |
Yukina | 0:c32a5fb80d4d | 185 | _4q1 = 4.0f * q1; |
Yukina | 0:c32a5fb80d4d | 186 | _4q2 = 4.0f * q2; |
Yukina | 0:c32a5fb80d4d | 187 | _8q1 = 8.0f * q1; |
Yukina | 0:c32a5fb80d4d | 188 | _8q2 = 8.0f * q2; |
Yukina | 0:c32a5fb80d4d | 189 | q0q0 = q0 * q0; |
Yukina | 0:c32a5fb80d4d | 190 | q1q1 = q1 * q1; |
Yukina | 0:c32a5fb80d4d | 191 | q2q2 = q2 * q2; |
Yukina | 0:c32a5fb80d4d | 192 | q3q3 = q3 * q3; |
Yukina | 0:c32a5fb80d4d | 193 | |
Yukina | 0:c32a5fb80d4d | 194 | // Gradient decent algorithm corrective step |
Yukina | 0:c32a5fb80d4d | 195 | s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay; |
Yukina | 0:c32a5fb80d4d | 196 | s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az; |
Yukina | 0:c32a5fb80d4d | 197 | s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az; |
Yukina | 0:c32a5fb80d4d | 198 | s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay; |
Yukina | 0:c32a5fb80d4d | 199 | recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude |
Yukina | 0:c32a5fb80d4d | 200 | s0 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 201 | s1 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 202 | s2 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 203 | s3 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 204 | |
Yukina | 0:c32a5fb80d4d | 205 | // Apply feedback step |
Yukina | 0:c32a5fb80d4d | 206 | qDot1 -= beta * s0; |
Yukina | 0:c32a5fb80d4d | 207 | qDot2 -= beta * s1; |
Yukina | 0:c32a5fb80d4d | 208 | qDot3 -= beta * s2; |
Yukina | 0:c32a5fb80d4d | 209 | qDot4 -= beta * s3; |
Yukina | 0:c32a5fb80d4d | 210 | } |
Yukina | 0:c32a5fb80d4d | 211 | |
Yukina | 0:c32a5fb80d4d | 212 | // Integrate rate of change of quaternion to yield quaternion |
Yukina | 0:c32a5fb80d4d | 213 | q0 += qDot1 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 214 | q1 += qDot2 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 215 | q2 += qDot3 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 216 | q3 += qDot4 * invSampleFreq; |
Yukina | 0:c32a5fb80d4d | 217 | |
Yukina | 0:c32a5fb80d4d | 218 | // Normalise quaternion |
Yukina | 0:c32a5fb80d4d | 219 | recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3); |
Yukina | 0:c32a5fb80d4d | 220 | q0 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 221 | q1 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 222 | q2 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 223 | q3 *= recipNorm; |
Yukina | 0:c32a5fb80d4d | 224 | anglesComputed = 0; |
Yukina | 0:c32a5fb80d4d | 225 | } |
Yukina | 0:c32a5fb80d4d | 226 | |
Yukina | 0:c32a5fb80d4d | 227 | //------------------------------------------------------------------------------------------- |
Yukina | 0:c32a5fb80d4d | 228 | // Fast inverse square-root |
Yukina | 0:c32a5fb80d4d | 229 | // See: http://en.wikipedia.org/wiki/Fast_inverse_square_root |
Yukina | 0:c32a5fb80d4d | 230 | |
Yukina | 0:c32a5fb80d4d | 231 | float Madgwick::invSqrt(float x) { |
Yukina | 0:c32a5fb80d4d | 232 | float halfx = 0.5f * x; |
Yukina | 0:c32a5fb80d4d | 233 | float y = x; |
Yukina | 0:c32a5fb80d4d | 234 | long i = *(long*)&y; |
Yukina | 0:c32a5fb80d4d | 235 | i = 0x5f3759df - (i>>1); |
Yukina | 0:c32a5fb80d4d | 236 | y = *(float*)&i; |
Yukina | 0:c32a5fb80d4d | 237 | y = y * (1.5f - (halfx * y * y)); |
Yukina | 0:c32a5fb80d4d | 238 | y = y * (1.5f - (halfx * y * y)); |
Yukina | 0:c32a5fb80d4d | 239 | return y; |
Yukina | 0:c32a5fb80d4d | 240 | } |
Yukina | 0:c32a5fb80d4d | 241 | |
Yukina | 0:c32a5fb80d4d | 242 | //------------------------------------------------------------------------------------------- |
Yukina | 0:c32a5fb80d4d | 243 | |
Yukina | 0:c32a5fb80d4d | 244 | void Madgwick::computeAngles() |
Yukina | 0:c32a5fb80d4d | 245 | { |
Yukina | 0:c32a5fb80d4d | 246 | roll = atan2f(q0*q1 + q2*q3, 0.5f - q1*q1 - q2*q2); |
Yukina | 0:c32a5fb80d4d | 247 | pitch = asinf(-2.0f * (q1*q3 - q0*q2)); |
Yukina | 0:c32a5fb80d4d | 248 | yaw = atan2f(q1*q2 + q0*q3, 0.5f - q2*q2 - q3*q3); |
Yukina | 0:c32a5fb80d4d | 249 | anglesComputed = 1; |
Yukina | 0:c32a5fb80d4d | 250 | } |
Yukina | 0:c32a5fb80d4d | 251 |