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43 lines
1.2 KiB
Plaintext
43 lines
1.2 KiB
Plaintext
/*
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Observation jacobian for fusion of the horizontal components of magnetometer measurements.
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innovation = atan2(magE/magN) - declination, where magN and magE are the North and East components obtained
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by rotating the measured magnetometer readings from body into earth axes.
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This method of fusion reduces roll and pitch errors due to external field disturbances and is suitable for initial alignment and ground / indoor use
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Divide by zero protection hs been added
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*/
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// calculate intermediate variables for observation jacobian
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float t9 = q0*q3;
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float t10 = q1*q2;
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float t2 = t9+t10;
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float t3 = q0*q0;
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float t4 = q1*q1;
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float t5 = q2*q2;
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float t6 = q3*q3;
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float t7 = t3+t4-t5-t6;
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float t8 = t7*t7;
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if (t8 > 1e-6f) {
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t8 = 1.0f/t8;
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} else {
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return;
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}
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float t11 = t2*t2;
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float t12 = t8*t11*4.0f;
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float t13 = t12+1.0f;
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float t14;
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if (fabsf(t13) > 1e-6f) {
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t14 = 1.0f/t13;
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} else {
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return;
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}
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// calculate observation jacobian
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float H_DECL[4] = {};
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H_YAW[0] = t8*t14*(q3*t3-q3*t4+q3*t5+q3*t6+q0*q1*q2*2.0f)*-2.0f;
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H_YAW[1] = t8*t14*(-q2*t3+q2*t4+q2*t5+q2*t6+q0*q1*q3*2.0f)*-2.0f;
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H_YAW[2] = t8*t14*(q1*t3+q1*t4+q1*t5-q1*t6+q0*q2*q3*2.0f)*2.0f;
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H_YAW[3] = t8*t14*(q0*t3+q0*t4-q0*t5+q0*t6+q1*q2*q3*2.0f)*2.0f;
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