-//=====================================================================================================\r
+/*\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
//\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
// 02/10/2011 SOH Madgwick Optimised for reduced CPU load\r
// 19/02/2012 SOH Madgwick Magnetometer measurement is normalised\r
//\r
-//=====================================================================================================\r
-\r
-//---------------------------------------------------------------------------------------------------\r
-// Header files\r
+//============================================================================\r
\r
#include "MadgwickAHRS.h"\r
#include <math.h>\r
\r
-\r
-//---------------------------------------------------------------------------------------------------\r
-// Definitions\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
-//---------------------------------------------------------------------------------------------------\r
-// Variable definitions\r
-\r
volatile float beta = betaDef; // 2 * proportional gain (Kp)\r
volatile float q0 = 1.0f, q1 = 0.0f, q2 = 0.0f, q3 = 0.0f; // quaternion of sensor frame relative to auxiliary frame\r
\r
\r
-//---------------------------------------------------------------------------------------------------\r
-// Function declarations\r
-\r
-float invSqrt(float x);\r
-\r
-//====================================================================================================\r
-// Functions\r
-\r
-//---------------------------------------------------------------------------------------------------\r
-// AHRS algorithm update\r
+static float invSqrt(float x)\r
+{\r
+ return 1.0f / sqrtf(x);\r
+}\r
\r
-void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) {\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, _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;\r
-\r
- // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)\r
- if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {\r
- MadgwickAHRSupdateIMU(gx, gy, gz, ax, ay, az);\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;\r
+ float q0 = quat->q0;\r
+ float q1 = quat->q1;\r
+ float q2 = quat->q2;\r
+ float q3 = quat->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
- // 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 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
- // Normalise magnetometer measurement\r
- recipNorm = invSqrt(mx * mx + my * my + mz * mz);\r
- mx *= recipNorm;\r
- my *= recipNorm;\r
- mz *= recipNorm;\r
-\r
- // Auxiliary variables to avoid repeated arithmetic\r
+ /* Rate of change of quaternion from gyroscope */\r
+ qDot1 = 0.5f * (-q1 * imu->gx - q2 * imu->gy - q3 * imu->gz);\r
+ qDot2 = 0.5f * (q0 * imu->gx + q2 * imu->gz - q3 * imu->gy);\r
+ qDot3 = 0.5f * (q0 * imu->gy - q1 * imu->gz + q3 * imu->gx);\r
+ qDot4 = 0.5f * (q0 * imu->gz + q1 * imu->gy - q2 * imu->gx);\r
+\r
+ /* Compute feedback only if accelerometer measurement valid (avoids NaN\r
+ * in accelerometer normalisation) */\r
+ if (!((imu->ax == 0.0f) && (imu->ay == 0.0f) && (imu->az == 0.0f))) {\r
+\r
+ /* Normalise accelerometer measurement */\r
+ recipNorm = invSqrt(imu->ax * imu->ax + imu->ay * imu->ay +\r
+ imu->az * imu->az);\r
+ ax = imu->ax * recipNorm;\r
+ ay = imu->ay * recipNorm;\r
+ az = imu->az * recipNorm;\r
+\r
+ /* Normalise magnetometer measurement */\r
+ recipNorm = invSqrt(imu->mx * imu->mx + imu->my * imu->my +\r
+ imu->mz * imu->mz);\r
+ mx = imu->mx * recipNorm;\r
+ my = imu->my * recipNorm;\r
+ mz = imu->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
q2q3 = q2 * q3;\r
q3q3 = q3 * q3;\r
\r
- // Reference direction of Earth's magnetic field\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
_4bx = 2.0f * _2bx;\r
_4bz = 2.0f * _2bz;\r
\r
- // Gradient decent algorithm corrective step\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
- recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude\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
+ /* Apply feedback step */\r
qDot1 -= beta * s0;\r
qDot2 -= beta * s1;\r
qDot3 -= beta * s2;\r
qDot4 -= beta * s3;\r
}\r
\r
- // Integrate rate of change of quaternion to yield quaternion\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
+ /* 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
+ quat->q0 = q0 * recipNorm;\r
+ quat->q1 = q1 * recipNorm;\r
+ quat->q2 = q2 * recipNorm;\r
+ quat->q3 = q3 * recipNorm;\r
}\r
\r
-//---------------------------------------------------------------------------------------------------\r
-// IMU algorithm update\r
-\r
-void MadgwickAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, float az) {\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;\r
+ float q0 = quat->q0;\r
+ float q1 = quat->q1;\r
+ float q2 = quat->q2;\r
+ float q3 = quat->q3;\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
+ /* Rate of change of quaternion from gyroscope */\r
+ qDot1 = 0.5f * (-q1 * imu->gx - q2 * imu->gy - q3 * imu->gz);\r
+ qDot2 = 0.5f * (q0 * imu->gx + q2 * imu->gz - q3 * imu->gy);\r
+ qDot3 = 0.5f * (q0 * imu->gy - q1 * imu->gz + q3 * imu->gx);\r
+ qDot4 = 0.5f * (q0 * imu->gz + q1 * imu->gy - q2 * imu->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
+ /* Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation) */\r
+ if(!((imu->ax == 0.0f) && (imu->ay == 0.0f) && (imu->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
+ /* Normalise accelerometer measurement */\r
+ recipNorm = invSqrt(imu->ax * imu->ax + imu->ay * imu->ay + imu->az * imu->az);\r
+ ax = imu->ax * recipNorm;\r
+ ay = imu->ay * recipNorm;\r
+ az = imu->az * recipNorm;\r
\r
- // Auxiliary variables to avoid repeated arithmetic\r
+ /* Auxiliary variables to avoid repeated arithmetic */\r
_2q0 = 2.0f * q0;\r
_2q1 = 2.0f * q1;\r
_2q2 = 2.0f * q2;\r
q2q2 = q2 * q2;\r
q3q3 = q3 * q3;\r
\r
-\r
- // Gradient decent algorithm corrective step\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
-\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
-\r
- // Apply feedback step\r
+ /* Apply feedback step */\r
qDot1 -= beta * s0;\r
qDot2 -= beta * s1;\r
qDot3 -= beta * s2;\r
qDot4 -= beta * s3;\r
}\r
\r
- // Integrate rate of change of quaternion to yield quaternion\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
-\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
- //printf("%+3.3f\t%+3.3f\t%+3.3f\r\n", q0, q1, q2);\r
-\r
+ /* Normalise quaternion */\r
+ recipNorm = invSqrt(q0 * q0 + q1 * q1 +\r
+ q2 * q2 + q3 * q3);\r
+ quat->q0 = q0 * recipNorm;\r
+ quat->q1 = q1 * recipNorm;\r
+ quat->q2 = q2 * recipNorm;\r
+ quat->q3 = q3 * recipNorm;\r
}\r
\r
-\r
-//---------------------------------------------------------------------------------------------------\r
-// Fast inverse square-root\r
-// See: http://en.wikipedia.org/wiki/Fast_inverse_square_root\r
-/*\r
-float invSqrt(float x) {\r
- float halfx = 0.5f * x;\r
- float y = x;\r
- long i = *(long*)&y;\r
- i = 0x5f3759df - (i>>1);\r
- y = *(float*)&i;\r
- y = y * (1.5f - (halfx * y * y));\r
- return y;\r
-}\r
-*/\r
-float invSqrt(float x) {\r
- return 1.0f / sqrtf(x);\r
-}\r
-//====================================================================================================\r
-// END OF CODE\r
-//====================================================================================================\r
git.droids-corp.org / protos / imu.git / blobdiff