/** * |---------------------------------------------------------------------- * | Copyright (c) 2016 Tilen MAJERLE * | * | Permission is hereby granted, free of charge, to any person * | obtaining a copy of this software and associated documentation * | files (the "Software"), to deal in the Software without restriction, * | including without limitation the rights to use, copy, modify, merge, * | publish, distribute, sublicense, and/or sell copies of the Software, * | and to permit persons to whom the Software is furnished to do so, * | subject to the following conditions: * | * | The above copyright notice and this permission notice shall be * | included in all copies or substantial portions of the Software. * | * | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * | EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES * | OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE * | AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT * | HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, * | WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * | FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * | OTHER DEALINGS IN THE SOFTWARE. * |---------------------------------------------------------------------- */ #include "tm_stm32_ahrs_imu.h" /* Calculate 1/sqrt(x) with magic number support */ static float oneOverSqrt(float x) { return 1.0f / (float) sqrt(x); } static void calculateAngles(TM_AHRSIMU_t* AHRSIMU) { AHRSIMU->Roll = (float) atan2(AHRSIMU->_q0 * AHRSIMU->_q1 + AHRSIMU->_q2 * AHRSIMU->_q3, 0.5f - AHRSIMU->_q1 * AHRSIMU->_q1 - AHRSIMU->_q2 * AHRSIMU->_q2); AHRSIMU->Pitch = (float) asin(-2.0f * (AHRSIMU->_q1 * AHRSIMU->_q3 - AHRSIMU->_q0 * AHRSIMU->_q2)); AHRSIMU->Yaw = (float) atan2(AHRSIMU->_q1 * AHRSIMU->_q2 + AHRSIMU->_q0 * AHRSIMU->_q3, 0.5f - AHRSIMU->_q2 * AHRSIMU->_q2 - AHRSIMU->_q3 * AHRSIMU->_q3); /* Calculate degrees and remove inclination */ AHRSIMU->Roll *= AHRSIMU_RAD2DEG(1); AHRSIMU->Pitch *= AHRSIMU_RAD2DEG(1); AHRSIMU->Yaw = AHRSIMU->Yaw * AHRSIMU_RAD2DEG(1) - AHRSIMU->Inclination; /* Check values because of inclination */ if (AHRSIMU->Yaw < -180) { AHRSIMU->Yaw = 180.0f - (-180.0f - AHRSIMU->Yaw); } else if (AHRSIMU->Yaw > 180) { AHRSIMU->Yaw = -180.0f - (180.0f - AHRSIMU->Yaw); } } void TM_AHRSIMU_Init(TM_AHRSIMU_t* AHRSIMU, float beta, float sampleRate, float inclination) { AHRSIMU->_beta = beta; AHRSIMU->_sampleRate = 1 / sampleRate; AHRSIMU->Inclination = inclination; AHRSIMU->_q0 = 1.0f; AHRSIMU->_q1 = 0.0f; AHRSIMU->_q2 = 0.0f; AHRSIMU->_q3 = 0.0f; } void TM_AHRSIMU_UpdateAHRS(TM_AHRSIMU_t* AHRSIMU, float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) { float recipNorm; float s0, s1, s2, s3; float qDot1, qDot2, qDot3, qDot4; float hx, hy; 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; /* Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation) */ if ((mx != 0.0f) || (my != 0.0f) || (mz != 0.0f)) { /* Rate of change of quaternion from gyroscope */ qDot1 = 0.5f * (-AHRSIMU->_q1 * gx - AHRSIMU->_q2 * gy - AHRSIMU->_q3 * gz); qDot2 = 0.5f * (AHRSIMU->_q0 * gx + AHRSIMU->_q2 * gz - AHRSIMU->_q3 * gy); qDot3 = 0.5f * (AHRSIMU->_q0 * gy - AHRSIMU->_q1 * gz + AHRSIMU->_q3 * gx); qDot4 = 0.5f * (AHRSIMU->_q0 * gz + AHRSIMU->_q1 * gy - AHRSIMU->_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 = oneOverSqrt(ax * ax + ay * ay + az * az); ax *= recipNorm; ay *= recipNorm; az *= recipNorm; /* Normalise magnetometer measurement */ recipNorm = oneOverSqrt(mx * mx + my * my + mz * mz); mx *= recipNorm; my *= recipNorm; mz *= recipNorm; /* Auxiliary variables to avoid repeated arithmetic */ _2q0mx = 2.0f * AHRSIMU->_q0 * mx; _2q0my = 2.0f * AHRSIMU->_q0 * my; _2q0mz = 2.0f * AHRSIMU->_q0 * mz; _2q1mx = 2.0f * AHRSIMU->_q1 * mx; _2q0 = 2.0f * AHRSIMU->_q0; _2q1 = 2.0f * AHRSIMU->_q1; _2q2 = 2.0f * AHRSIMU->_q2; _2q3 = 2.0f * AHRSIMU->_q3; _2q0q2 = 2.0f * AHRSIMU->_q0 * AHRSIMU->_q2; _2q2q3 = 2.0f * AHRSIMU->_q2 * AHRSIMU->_q3; q0q0 = AHRSIMU->_q0 * AHRSIMU->_q0; q0q1 = AHRSIMU->_q0 * AHRSIMU->_q1; q0q2 = AHRSIMU->_q0 * AHRSIMU->_q2; q0q3 = AHRSIMU->_q0 * AHRSIMU->_q3; q1q1 = AHRSIMU->_q1 * AHRSIMU->_q1; q1q2 = AHRSIMU->_q1 * AHRSIMU->_q2; q1q3 = AHRSIMU->_q1 * AHRSIMU->_q3; q2q2 = AHRSIMU->_q2 * AHRSIMU->_q2; q2q3 = AHRSIMU->_q2 * AHRSIMU->_q3; q3q3 = AHRSIMU->_q3 * AHRSIMU->_q3; /* Reference direction of Earth's magnetic field */ hx = mx * q0q0 - _2q0my * AHRSIMU->_q3 + _2q0mz * AHRSIMU->_q2 + mx * q1q1 + _2q1 * my * AHRSIMU->_q2 + _2q1 * mz * AHRSIMU->_q3 - mx * q2q2 - mx * q3q3; hy = _2q0mx * AHRSIMU->_q3 + my * q0q0 - _2q0mz * AHRSIMU->_q1 + _2q1mx * AHRSIMU->_q2 - my * q1q1 + my * q2q2 + _2q2 * mz * AHRSIMU->_q3 - my * q3q3; _2bx = (float) sqrt(hx * hx + hy * hy); _2bz = -_2q0mx * AHRSIMU->_q2 + _2q0my * AHRSIMU->_q1 + mz * q0q0 + _2q1mx * AHRSIMU->_q3 - mz * q1q1 + _2q2 * my * AHRSIMU->_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 * AHRSIMU->_q2 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * AHRSIMU->_q3 + _2bz * AHRSIMU->_q1) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * AHRSIMU->_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 * AHRSIMU->_q1 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + _2bz * AHRSIMU->_q3 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * AHRSIMU->_q2 + _2bz * AHRSIMU->_q0) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * AHRSIMU->_q3 - _4bz * AHRSIMU->_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 * AHRSIMU->_q2 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + (-_4bx * AHRSIMU->_q2 - _2bz * AHRSIMU->_q0) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * AHRSIMU->_q1 + _2bz * AHRSIMU->_q3) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * AHRSIMU->_q0 - _4bz * AHRSIMU->_q2) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz); s3 = _2q1 * (2.0f * q1q3 - _2q0q2 - ax) + _2q2 * (2.0f * q0q1 + _2q2q3 - ay) + (-_4bx * AHRSIMU->_q3 + _2bz * AHRSIMU->_q1) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * AHRSIMU->_q0 + _2bz * AHRSIMU->_q2) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * AHRSIMU->_q1 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz); /* normalise step magnitude */ recipNorm = oneOverSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); s0 *= recipNorm; s1 *= recipNorm; s2 *= recipNorm; s3 *= recipNorm; /* Apply feedback step */ qDot1 -= AHRSIMU->_beta * s0; qDot2 -= AHRSIMU->_beta * s1; qDot3 -= AHRSIMU->_beta * s2; qDot4 -= AHRSIMU->_beta * s3; } /* Integrate rate of change of quaternion to yield quaternion */ AHRSIMU->_q0 += qDot1 * AHRSIMU->_sampleRate; AHRSIMU->_q1 += qDot2 * AHRSIMU->_sampleRate; AHRSIMU->_q2 += qDot3 * AHRSIMU->_sampleRate; AHRSIMU->_q3 += qDot4 * AHRSIMU->_sampleRate; /* Normalise quaternion */ recipNorm = oneOverSqrt(AHRSIMU->_q0 * AHRSIMU->_q0 + AHRSIMU->_q1 * AHRSIMU->_q1 + AHRSIMU->_q2 * AHRSIMU->_q2 + AHRSIMU->_q3 * AHRSIMU->_q3); AHRSIMU->_q0 *= recipNorm; AHRSIMU->_q1 *= recipNorm; AHRSIMU->_q2 *= recipNorm; AHRSIMU->_q3 *= recipNorm; } else { /* Update IMU algorithm */ TM_AHRSIMU_UpdateIMU(AHRSIMU, gx, gy, gz, ax, ay, az); } /* Calculate new angles */ calculateAngles(AHRSIMU); } void TM_AHRSIMU_UpdateIMU(TM_AHRSIMU_t* AHRSIMU, float gx, float gy, float gz, float ax, float ay, float az) { 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; /* Rate of change of quaternion from gyroscope */ qDot1 = 0.5f * (-AHRSIMU->_q1 * gx - AHRSIMU->_q2 * gy - AHRSIMU->_q3 * gz); qDot2 = 0.5f * (AHRSIMU->_q0 * gx + AHRSIMU->_q2 * gz - AHRSIMU->_q3 * gy); qDot3 = 0.5f * (AHRSIMU->_q0 * gy - AHRSIMU->_q1 * gz + AHRSIMU->_q3 * gx); qDot4 = 0.5f * (AHRSIMU->_q0 * gz + AHRSIMU->_q1 * gy - AHRSIMU->_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 = oneOverSqrt(ax * ax + ay * ay + az * az); ax *= recipNorm; ay *= recipNorm; az *= recipNorm; /* Auxiliary variables to avoid repeated arithmetic */ _2q0 = 2.0f * AHRSIMU->_q0; _2q1 = 2.0f * AHRSIMU->_q1; _2q2 = 2.0f * AHRSIMU->_q2; _2q3 = 2.0f * AHRSIMU->_q3; _4q0 = 4.0f * AHRSIMU->_q0; _4q1 = 4.0f * AHRSIMU->_q1; _4q2 = 4.0f * AHRSIMU->_q2; _8q1 = 8.0f * AHRSIMU->_q1; _8q2 = 8.0f * AHRSIMU->_q2; q0q0 = AHRSIMU->_q0 * AHRSIMU->_q0; q1q1 = AHRSIMU->_q1 * AHRSIMU->_q1; q2q2 = AHRSIMU->_q2 * AHRSIMU->_q2; q3q3 = AHRSIMU->_q3 * AHRSIMU->_q3; /* Gradient decent algorithm corrective step */ s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay; s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * AHRSIMU->_q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az; s2 = 4.0f * q0q0 * AHRSIMU->_q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az; s3 = 4.0f * q1q1 * AHRSIMU->_q3 - _2q1 * ax + 4.0f * q2q2 * AHRSIMU->_q3 - _2q2 * ay; /* Normalise step magnitude */ recipNorm = oneOverSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); s0 *= recipNorm; s1 *= recipNorm; s2 *= recipNorm; s3 *= recipNorm; /* Apply feedback step */ qDot1 -= AHRSIMU->_beta * s0; qDot2 -= AHRSIMU->_beta * s1; qDot3 -= AHRSIMU->_beta * s2; qDot4 -= AHRSIMU->_beta * s3; } /* Integrate rate of change of quaternion to yield quaternion */ AHRSIMU->_q0 += qDot1 * AHRSIMU->_sampleRate; AHRSIMU->_q1 += qDot2 * AHRSIMU->_sampleRate; AHRSIMU->_q2 += qDot3 * AHRSIMU->_sampleRate; AHRSIMU->_q3 += qDot4 * AHRSIMU->_sampleRate; /* Normalise quaternion */ recipNorm = oneOverSqrt(AHRSIMU->_q0 * AHRSIMU->_q0 + AHRSIMU->_q1 * AHRSIMU->_q1 + AHRSIMU->_q2 * AHRSIMU->_q2 + AHRSIMU->_q3 * AHRSIMU->_q3); AHRSIMU->_q0 *= recipNorm; AHRSIMU->_q1 *= recipNorm; AHRSIMU->_q2 *= recipNorm; AHRSIMU->_q3 *= recipNorm; /* Calculate new angles */ calculateAngles(AHRSIMU); }