-/*\r
- * Copyright (c) 2014, Olivier MATZ <zer0@droids-corp.org>\r
- * Copyright (c) 2011-2012, SOH Madgwick\r
- *\r
- * This program is free software: you can redistribute it and/or modify\r
- * it under the terms of the GNU General Public License as published by\r
- * the Free Software Foundation, either version 3 of the License, or\r
- * (at your option) any later version.\r
- *\r
- * This program is distributed in the hope that it will be useful,\r
- * but WITHOUT ANY WARRANTY; without even the implied warranty of\r
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the\r
- * GNU General Public License for more details.\r
- *\r
- * You should have received a copy of the GNU General Public License\r
- * along with this program. If not, see <http://www.gnu.org/licenses/>.\r
- *\r
- */\r
-\r
-//============================================================================\r
-// MadgwickAHRS.c\r
-//============================================================================\r
-//\r
-// Implementation of Madgwick's IMU and AHRS algorithms.\r
-// See: http://www.x-io.co.uk/node/8#open_source_ahrs_and_imu_algorithms\r
-//\r
-// Date Author Notes\r
-// 29/09/2011 SOH Madgwick Initial release\r
-// 02/10/2011 SOH Madgwick Optimised for reduced CPU load\r
-// 19/02/2012 SOH Madgwick Magnetometer measurement is normalised\r
-//\r
-//============================================================================\r
-\r
-#include "MadgwickAHRS.h"\r
-#include <math.h>\r
-\r
-//#define sampleFreq 512.0f // sample frequency in Hz\r
-//#define sampleFreq 46.0f // sample frequency in Hz\r
-#define sampleFreq 85.0f // sample frequency in Hz\r
-#define betaDef 0.1f // 2 * proportional gain\r
-\r
-static float invSqrt(float x)\r
-{\r
- return 1.0f / sqrtf(x);\r
-}\r
-\r
-/* AHRS algorithm update */\r
-void MadgwickAHRSupdate(const struct imu_info *imu, struct quaternion *quat)\r
-{\r
- float recipNorm;\r
- float s0, s1, s2, s3;\r
- float qDot1, qDot2, qDot3, qDot4;\r
- float hx, hy;\r
- float _2q0mx, _2q0my, _2q0mz, _2q1mx, _2bx, _2bz, _4bx, _4bz;\r
- float _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3;\r
- float q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;\r
- float mx, my, mz, ax, ay, az, gx, gy, gz;\r
- float q0, q1, q2, q3;\r
-\r
- /* Use IMU algorithm if magnetometer measurement invalid (avoids NaN in\r
- * magnetometer normalisation) */\r
- if ((imu->mx == 0.0f) && (imu->my == 0.0f) && (imu->mz == 0.0f)) {\r
- MadgwickAHRSupdateIMU(imu, quat);\r
- return;\r
- }\r
-\r
- /* use local variables, it's more readable */\r
- q0 = quat->q0; q1 = quat->q1; q2 = quat->q2; q3 = quat->q3;\r
- gx = imu->gx; gy = imu->gy; gz = imu->gz;\r
- ax = imu->ax; ay = imu->ay; az = imu->az;\r
- mx = imu->mx; my = imu->my; mz = imu->mz;\r
-\r
- /* Rate of change of quaternion from gyroscope */\r
- qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);\r
- qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);\r
- qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);\r
- qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);\r
-\r
- /* Compute feedback only if accelerometer measurement valid (avoids NaN\r
- * in accelerometer normalisation) */\r
- if (!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {\r
-\r
- /* Normalise accelerometer measurement */\r
- recipNorm = invSqrt(ax * ax + ay * ay +\r
- az * az);\r
- ax *= recipNorm;\r
- ay *= recipNorm;\r
- az *= recipNorm;\r
-\r
- /* Normalise magnetometer measurement */\r
- recipNorm = invSqrt(mx * mx + my * my +\r
- mz * mz);\r
- mx *= recipNorm;\r
- my *= recipNorm;\r
- mz *= recipNorm;\r
-\r
- /* Auxiliary variables to avoid repeated arithmetic */\r
- _2q0mx = 2.0f * q0 * mx;\r
- _2q0my = 2.0f * q0 * my;\r
- _2q0mz = 2.0f * q0 * mz;\r
- _2q1mx = 2.0f * q1 * mx;\r
- _2q0 = 2.0f * q0;\r
- _2q1 = 2.0f * q1;\r
- _2q2 = 2.0f * q2;\r
- _2q3 = 2.0f * q3;\r
- _2q0q2 = 2.0f * q0 * q2;\r
- _2q2q3 = 2.0f * q2 * q3;\r
- q0q0 = q0 * q0;\r
- q0q1 = q0 * q1;\r
- q0q2 = q0 * q2;\r
- q0q3 = q0 * q3;\r
- q1q1 = q1 * q1;\r
- q1q2 = q1 * q2;\r
- q1q3 = q1 * q3;\r
- q2q2 = q2 * q2;\r
- q2q3 = q2 * q3;\r
- q3q3 = q3 * q3;\r
-\r
- /* Reference direction of Earth's magnetic field */\r
- hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;\r
- hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;\r
- _2bx = sqrt(hx * hx + hy * hy);\r
- _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;\r
- _4bx = 2.0f * _2bx;\r
- _4bz = 2.0f * _2bz;\r
-\r
- /* Gradient decent algorithm corrective step */\r
- 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);\r
- 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);\r
- 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);\r
- 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);\r
-\r
- /* normalize step magnitude */\r
- recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3);\r
- s0 *= recipNorm;\r
- s1 *= recipNorm;\r
- s2 *= recipNorm;\r
- s3 *= recipNorm;\r
-\r
- /* Apply feedback step */\r
- qDot1 -= betaDef * s0;\r
- qDot2 -= betaDef * s1;\r
- qDot3 -= betaDef * s2;\r
- qDot4 -= betaDef * s3;\r
- }\r
-\r
- /* Integrate rate of change of quaternion to yield quaternion */\r
- q0 += qDot1 * (1.0f / sampleFreq);\r
- q1 += qDot2 * (1.0f / sampleFreq);\r
- q2 += qDot3 * (1.0f / sampleFreq);\r
- q3 += qDot4 * (1.0f / sampleFreq);\r
-\r
- /* Normalise quaternion */\r
- recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);\r
- q0 *= recipNorm;\r
- q1 *= recipNorm;\r
- q2 *= recipNorm;\r
- q3 *= recipNorm;\r
-\r
- /* update quaternion in structure */\r
- quat->q0 = q0;\r
- quat->q1 = q1;\r
- quat->q2 = q2;\r
- quat->q3 = q3;\r
-}\r
-\r
-/* IMU algorithm update (does not take magneto in account) */\r
-void MadgwickAHRSupdateIMU(const struct imu_info *imu, struct quaternion *quat)\r
-{\r
- float recipNorm;\r
- float s0, s1, s2, s3;\r
- float qDot1, qDot2, qDot3, qDot4;\r
- float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;\r
- float ax, ay, az, gx, gy, gz;\r
- float q0, q1, q2, q3;\r
-\r
- /* use local variables, it's more readable */\r
- q0 = quat->q0; q1 = quat->q1; q2 = quat->q2; q3 = quat->q3;\r
- gx = imu->gx; gy = imu->gy; gz = imu->gz;\r
- ax = imu->ax; ay = imu->ay; az = imu->az;\r
-\r
- /* Rate of change of quaternion from gyroscope */\r
- qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);\r
- qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);\r
- qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);\r
- qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);\r
-\r
-\r
- /* Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation) */\r
- if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {\r
-\r
- /* Normalise accelerometer measurement */\r
- recipNorm = invSqrt(ax * ax + ay * ay + az * az);\r
- ax *= recipNorm;\r
- ay *= recipNorm;\r
- az *= recipNorm;\r
-\r
- /* Auxiliary variables to avoid repeated arithmetic */\r
- _2q0 = 2.0f * q0;\r
- _2q1 = 2.0f * q1;\r
- _2q2 = 2.0f * q2;\r
- _2q3 = 2.0f * q3;\r
- _4q0 = 4.0f * q0;\r
- _4q1 = 4.0f * q1;\r
- _4q2 = 4.0f * q2;\r
- _8q1 = 8.0f * q1;\r
- _8q2 = 8.0f * q2;\r
- q0q0 = q0 * q0;\r
- q1q1 = q1 * q1;\r
- q2q2 = q2 * q2;\r
- q3q3 = q3 * q3;\r
-\r
- /* Gradient decent algorithm corrective step */\r
- s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;\r
- s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;\r
- s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;\r
- s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;\r
- recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); /* normalise step magnitude */\r
-\r
- s0 *= recipNorm;\r
- s1 *= recipNorm;\r
- s2 *= recipNorm;\r
- s3 *= recipNorm;\r
-\r
- /* Apply feedback step */\r
- qDot1 -= betaDef * s0;\r
- qDot2 -= betaDef * s1;\r
- qDot3 -= betaDef * s2;\r
- qDot4 -= betaDef * s3;\r
- }\r
-\r
- /* Integrate rate of change of quaternion to yield quaternion */\r
- q0 += qDot1 * (1.0f / sampleFreq);\r
- q1 += qDot2 * (1.0f / sampleFreq);\r
- q2 += qDot3 * (1.0f / sampleFreq);\r
- q3 += qDot4 * (1.0f / sampleFreq);\r
-\r
- /* Normalise quaternion */\r
- recipNorm = invSqrt(q0 * q0 + q1 * q1 +\r
- q2 * q2 + q3 * q3);\r
- q0 *= recipNorm;\r
- q1 *= recipNorm;\r
- q2 *= recipNorm;\r
- q3 *= recipNorm;\r
-\r
- /* update quaternion in structure */\r
- quat->q0 = q0;\r
- quat->q1 = q1;\r
- quat->q2 = q2;\r
- quat->q3 = q3;\r
-}\r
-\r
+/*
+ * Copyright (c) 2014, Olivier MATZ <zer0@droids-corp.org>
+ * Copyright (c) 2011-2012, SOH Madgwick
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+//============================================================================
+// MadgwickAHRS.c
+//============================================================================
+//
+// Implementation of Madgwick's IMU and AHRS algorithms.
+// See: http://www.x-io.co.uk/node/8#open_source_ahrs_and_imu_algorithms
+//
+// Date Author Notes
+// 29/09/2011 SOH Madgwick Initial release
+// 02/10/2011 SOH Madgwick Optimised for reduced CPU load
+// 19/02/2012 SOH Madgwick Magnetometer measurement is normalised
+//
+//============================================================================
+
+#include "MadgwickAHRS.h"
+#include <math.h>
+
+//#define sampleFreq 512.0f // sample frequency in Hz
+//#define sampleFreq 46.0f // sample frequency in Hz
+#define sampleFreq 85.0f // sample frequency in Hz
+#define betaDef 0.1f // 2 * proportional gain
+
+static float invSqrt(float x)
+{
+ return 1.0f / sqrtf(x);
+}
+
+/* AHRS algorithm update */
+void MadgwickAHRSupdate(const struct imu_info *imu, struct quaternion *quat)
+{
+ float recipNorm;
+ float s0, s1, s2, s3;
+ float qDot1, qDot2, qDot3, qDot4;
+ float hx, hy;
+ float _2q0mx, _2q0my, _2q0mz, _2q1mx, _2bx, _2bz, _4bx, _4bz;
+ float _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3;
+ float q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;
+ float mx, my, mz, ax, ay, az, gx, gy, gz;
+ float q0, q1, q2, q3;
+
+ /* Use IMU algorithm if magnetometer measurement invalid (avoids NaN in
+ * magnetometer normalisation) */
+ if ((imu->mx == 0.0f) && (imu->my == 0.0f) && (imu->mz == 0.0f)) {
+ MadgwickAHRSupdateIMU(imu, quat);
+ return;
+ }
+
+ /* use local variables, it's more readable */
+ q0 = quat->q0; q1 = quat->q1; q2 = quat->q2; q3 = quat->q3;
+ gx = imu->gx; gy = imu->gy; gz = imu->gz;
+ ax = imu->ax; ay = imu->ay; az = imu->az;
+ mx = imu->mx; my = imu->my; mz = imu->mz;
+
+ /* Rate of change of quaternion from gyroscope */
+ qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
+ qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
+ qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
+ qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
+
+ /* Compute feedback only if accelerometer measurement valid (avoids NaN
+ * in accelerometer normalisation) */
+ if (!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
+
+ /* Normalise accelerometer measurement */
+ recipNorm = invSqrt(ax * ax + ay * ay +
+ az * az);
+ ax *= recipNorm;
+ ay *= recipNorm;
+ az *= recipNorm;
+
+ /* Normalise magnetometer measurement */
+ recipNorm = invSqrt(mx * mx + my * my +
+ mz * mz);
+ mx *= recipNorm;
+ my *= recipNorm;
+ mz *= recipNorm;
+
+ /* Auxiliary variables to avoid repeated arithmetic */
+ _2q0mx = 2.0f * q0 * mx;
+ _2q0my = 2.0f * q0 * my;
+ _2q0mz = 2.0f * q0 * mz;
+ _2q1mx = 2.0f * q1 * mx;
+ _2q0 = 2.0f * q0;
+ _2q1 = 2.0f * q1;
+ _2q2 = 2.0f * q2;
+ _2q3 = 2.0f * q3;
+ _2q0q2 = 2.0f * q0 * q2;
+ _2q2q3 = 2.0f * q2 * q3;
+ q0q0 = q0 * q0;
+ q0q1 = q0 * q1;
+ q0q2 = q0 * q2;
+ q0q3 = q0 * q3;
+ q1q1 = q1 * q1;
+ q1q2 = q1 * q2;
+ q1q3 = q1 * q3;
+ q2q2 = q2 * q2;
+ q2q3 = q2 * q3;
+ q3q3 = q3 * q3;
+
+ /* Reference direction of Earth's magnetic field */
+ hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;
+ hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;
+ _2bx = sqrt(hx * hx + hy * hy);
+ _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;
+ _4bx = 2.0f * _2bx;
+ _4bz = 2.0f * _2bz;
+
+ /* Gradient decent algorithm corrective step */
+ 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);
+ 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);
+ 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);
+ 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);
+
+ /* normalize step magnitude */
+ recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3);
+ s0 *= recipNorm;
+ s1 *= recipNorm;
+ s2 *= recipNorm;
+ s3 *= recipNorm;
+
+ /* Apply feedback step */
+ qDot1 -= betaDef * s0;
+ qDot2 -= betaDef * s1;
+ qDot3 -= betaDef * s2;
+ qDot4 -= betaDef * s3;
+ }
+
+ /* Integrate rate of change of quaternion to yield quaternion */
+ q0 += qDot1 * (1.0f / sampleFreq);
+ q1 += qDot2 * (1.0f / sampleFreq);
+ q2 += qDot3 * (1.0f / sampleFreq);
+ q3 += qDot4 * (1.0f / sampleFreq);
+
+ /* Normalise quaternion */
+ recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
+ q0 *= recipNorm;
+ q1 *= recipNorm;
+ q2 *= recipNorm;
+ q3 *= recipNorm;
+
+ /* update quaternion in structure */
+ quat->q0 = q0;
+ quat->q1 = q1;
+ quat->q2 = q2;
+ quat->q3 = q3;
+}
+
+/* IMU algorithm update (does not take magneto in account) */
+void MadgwickAHRSupdateIMU(const struct imu_info *imu, struct quaternion *quat)
+{
+ float recipNorm;
+ float s0, s1, s2, s3;
+ float qDot1, qDot2, qDot3, qDot4;
+ float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;
+ float ax, ay, az, gx, gy, gz;
+ float q0, q1, q2, q3;
+
+ /* use local variables, it's more readable */
+ q0 = quat->q0; q1 = quat->q1; q2 = quat->q2; q3 = quat->q3;
+ gx = imu->gx; gy = imu->gy; gz = imu->gz;
+ ax = imu->ax; ay = imu->ay; az = imu->az;
+
+ /* Rate of change of quaternion from gyroscope */
+ qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
+ qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
+ qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
+ qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);
+
+
+ /* Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation) */
+ if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
+
+ /* Normalise accelerometer measurement */
+ recipNorm = invSqrt(ax * ax + ay * ay + az * az);
+ ax *= recipNorm;
+ ay *= recipNorm;
+ az *= recipNorm;
+
+ /* Auxiliary variables to avoid repeated arithmetic */
+ _2q0 = 2.0f * q0;
+ _2q1 = 2.0f * q1;
+ _2q2 = 2.0f * q2;
+ _2q3 = 2.0f * q3;
+ _4q0 = 4.0f * q0;
+ _4q1 = 4.0f * q1;
+ _4q2 = 4.0f * q2;
+ _8q1 = 8.0f * q1;
+ _8q2 = 8.0f * q2;
+ q0q0 = q0 * q0;
+ q1q1 = q1 * q1;
+ q2q2 = q2 * q2;
+ q3q3 = q3 * q3;
+
+ /* Gradient decent algorithm corrective step */
+ s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
+ s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
+ s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
+ s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;
+ recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); /* normalise step magnitude */
+
+ s0 *= recipNorm;
+ s1 *= recipNorm;
+ s2 *= recipNorm;
+ s3 *= recipNorm;
+
+ /* Apply feedback step */
+ qDot1 -= betaDef * s0;
+ qDot2 -= betaDef * s1;
+ qDot3 -= betaDef * s2;
+ qDot4 -= betaDef * s3;
+ }
+
+ /* Integrate rate of change of quaternion to yield quaternion */
+ q0 += qDot1 * (1.0f / sampleFreq);
+ q1 += qDot2 * (1.0f / sampleFreq);
+ q2 += qDot3 * (1.0f / sampleFreq);
+ q3 += qDot4 * (1.0f / sampleFreq);
+
+ /* Normalise quaternion */
+ recipNorm = invSqrt(q0 * q0 + q1 * q1 +
+ q2 * q2 + q3 * q3);
+ q0 *= recipNorm;
+ q1 *= recipNorm;
+ q2 *= recipNorm;
+ q3 *= recipNorm;
+
+ /* update quaternion in structure */
+ quat->q0 = q0;
+ quat->q1 = q1;
+ quat->q2 = q2;
+ quat->q3 = q3;
+}
+
git.droids-corp.org / fpv.git / commitdiff