168 lines
6.6 KiB
C++
168 lines
6.6 KiB
C++
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#include "madgwick.h"
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volatile float beta = 0.1f;
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void madgwickQuaternionUpdate(float q[4], float ax, float ay, float az, float gx, float gy, float gz, float deltat)
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{
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float recipNorm;
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float s0, s1, s2, s3;
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float qDot1, qDot2, qDot3, qDot4;
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float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;
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// Rate of change of quaternion from gyroscope
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qDot1 = 0.5f * (-q[1] * gx - q[2] * gy - q[3] * gz);
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qDot2 = 0.5f * (q[0] * gx + q[2] * gz - q[3] * gy);
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qDot3 = 0.5f * (q[0] * gy - q[1] * gz + q[3] * gx);
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qDot4 = 0.5f * (q[0] * gz + q[1] * gy - q[2] * gx);
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// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
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if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
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// Normalise accelerometer measurement
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recipNorm = invSqrt(ax * ax + ay * ay + az * az);
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ax *= recipNorm;
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ay *= recipNorm;
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az *= recipNorm;
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// Auxiliary variables to avoid repeated arithmetic
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_2q0 = 2.0f * q[0];
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_2q1 = 2.0f * q[1];
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_2q2 = 2.0f * q[2];
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_2q3 = 2.0f * q[3];
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_4q0 = 4.0f * q[0];
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_4q1 = 4.0f * q[1];
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_4q2 = 4.0f * q[2];
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_8q1 = 8.0f * q[1];
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_8q2 = 8.0f * q[2];
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q0q0 = q[0] * q[0];
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q1q1 = q[1] * q[1];
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q2q2 = q[2] * q[2];
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q3q3 = q[3] * q[3];
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// Gradient decent algorithm corrective step
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s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
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s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q[1] - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
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s2 = 4.0f * q0q0 * q[2] + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
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s3 = 4.0f * q1q1 * q[3] - _2q1 * ax + 4.0f * q2q2 * q[3] - _2q2 * ay;
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recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
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s0 *= recipNorm;
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s1 *= recipNorm;
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s2 *= recipNorm;
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s3 *= recipNorm;
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// Apply feedback step
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qDot1 -= beta * s0;
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qDot2 -= beta * s1;
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qDot3 -= beta * s2;
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qDot4 -= beta * s3;
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}
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// Integrate rate of change of quaternion to yield quaternion
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q[0] += qDot1 * deltat;
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q[1] += qDot2 * deltat;
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q[2] += qDot3 * deltat;
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q[3] += qDot4 * deltat;
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// Normalise quaternion
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recipNorm = invSqrt(q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]);
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q[0] *= recipNorm;
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q[1] *= recipNorm;
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q[2] *= recipNorm;
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q[3] *= recipNorm;
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}
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void madgwickQuaternionUpdate(float q[4], float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz, float deltat)
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{
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float recipNorm;
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float s0, s1, s2, s3;
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float qDot1, qDot2, qDot3, qDot4;
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float hx, hy;
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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;
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// Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)
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if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
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madgwickQuaternionUpdate(q, ax, ay, az, gx, gy, gz, deltat);
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return;
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}
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// Rate of change of quaternion from gyroscope
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qDot1 = 0.5f * (-q[1] * gx - q[2] * gy - q[3] * gz);
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qDot2 = 0.5f * (q[0] * gx + q[2] * gz - q[3] * gy);
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qDot3 = 0.5f * (q[0] * gy - q[1] * gz + q[3] * gx);
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qDot4 = 0.5f * (q[0] * gz + q[1] * gy - q[2] * gx);
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// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
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if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
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// Normalise accelerometer measurement
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recipNorm = invSqrt(ax * ax + ay * ay + az * az);
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ax *= recipNorm;
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ay *= recipNorm;
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az *= recipNorm;
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// Normalise magnetometer measurement
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recipNorm = invSqrt(mx * mx + my * my + mz * mz);
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mx *= recipNorm;
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my *= recipNorm;
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mz *= recipNorm;
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// Auxiliary variables to avoid repeated arithmetic
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_2q0mx = 2.0f * q[0] * mx;
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_2q0my = 2.0f * q[0] * my;
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_2q0mz = 2.0f * q[0] * mz;
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_2q1mx = 2.0f * q[1] * mx;
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_2q0 = 2.0f * q[0];
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_2q1 = 2.0f * q[1];
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_2q2 = 2.0f * q[2];
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_2q3 = 2.0f * q[3];
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_2q0q2 = 2.0f * q[0] * q[2];
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_2q2q3 = 2.0f * q[2] * q[3];
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q0q0 = q[0] * q[0];
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q0q1 = q[0] * q[1];
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q0q2 = q[0] * q[2];
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q0q3 = q[0] * q[3];
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q1q1 = q[1] * q[1];
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q1q2 = q[1] * q[2];
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q1q3 = q[1] * q[3];
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q2q2 = q[2] * q[2];
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q2q3 = q[2] * q[3];
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q3q3 = q[3] * q[3];
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// Reference direction of Earth's magnetic field
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hx = mx * q0q0 - _2q0my * q[3] + _2q0mz * q[2] + mx * q1q1 + _2q1 * my * q[2] + _2q1 * mz * q[3] - mx * q2q2 - mx * q3q3;
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hy = _2q0mx * q[3] + my * q0q0 - _2q0mz * q[1] + _2q1mx * q[2] - my * q1q1 + my * q2q2 + _2q2 * mz * q[3] - my * q3q3;
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_2bx = sqrt(hx * hx + hy * hy);
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_2bz = -_2q0mx * q[2] + _2q0my * q[1] + mz * q0q0 + _2q1mx * q[3] - mz * q1q1 + _2q2 * my * q[3] - mz * q2q2 + mz * q3q3;
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_4bx = 2.0f * _2bx;
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_4bz = 2.0f * _2bz;
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// Gradient decent algorithm corrective step
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s0 = -_2q2 * (2.0f * q1q3 - _2q0q2 - ax) + _2q1 * (2.0f * q0q1 + _2q2q3 - ay) - _2bz * q[2] * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q[3] + _2bz * q[1]) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q[2] * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
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s1 = _2q3 * (2.0f * q1q3 - _2q0q2 - ax) + _2q0 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q[1] * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + _2bz * q[3] * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q[2] + _2bz * q[0]) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q[3] - _4bz * q[1]) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
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s2 = -_2q0 * (2.0f * q1q3 - _2q0q2 - ax) + _2q3 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q[2] * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + (-_4bx * q[2] - _2bz * q[0]) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q[1] + _2bz * q[3]) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q[0] - _4bz * q[2]) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
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s3 = _2q1 * (2.0f * q1q3 - _2q0q2 - ax) + _2q2 * (2.0f * q0q1 + _2q2q3 - ay) + (-_4bx * q[3] + _2bz * q[1]) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q[0] + _2bz * q[2]) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q[1] * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
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recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
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s0 *= recipNorm;
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s1 *= recipNorm;
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s2 *= recipNorm;
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s3 *= recipNorm;
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// Apply feedback step
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qDot1 -= beta * s0;
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qDot2 -= beta * s1;
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qDot3 -= beta * s2;
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qDot4 -= beta * s3;
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}
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// Integrate rate of change of quaternion to yield quaternion
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q[0] += qDot1 * deltat;
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q[1] += qDot2 * deltat;
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q[2] += qDot3 * deltat;
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q[3] += qDot4 * deltat;
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// Normalise quaternion
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recipNorm = invSqrt(q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]);
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q[0] *= recipNorm;
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q[1] *= recipNorm;
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q[2] *= recipNorm;
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q[3] *= recipNorm;
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}
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