diff options
Diffstat (limited to 'apps/systemlib')
-rw-r--r-- | apps/systemlib/conversions.c | 89 | ||||
-rw-r--r-- | apps/systemlib/conversions.h | 22 |
2 files changed, 111 insertions, 0 deletions
diff --git a/apps/systemlib/conversions.c b/apps/systemlib/conversions.c index 9105d83cb..32df446d9 100644 --- a/apps/systemlib/conversions.c +++ b/apps/systemlib/conversions.c @@ -55,3 +55,92 @@ int16_t_from_bytes(uint8_t bytes[]) return u.w; } + +void rot2quat(const float R[9], float Q[4]) +{ + float q0_2; + float q1_2; + float q2_2; + float q3_2; + int32_t idx; + + /* conversion of rotation matrix to quaternion + * choose the largest component to begin with */ + q0_2 = (((1.0F + R[0]) + R[4]) + R[8]) / 4.0F; + q1_2 = (((1.0F + R[0]) - R[4]) - R[8]) / 4.0F; + q2_2 = (((1.0F - R[0]) + R[4]) - R[8]) / 4.0F; + q3_2 = (((1.0F - R[0]) - R[4]) + R[8]) / 4.0F; + + idx = 0; + + if (q0_2 < q1_2) { + q0_2 = q1_2; + + idx = 1; + } + + if (q0_2 < q2_2) { + q0_2 = q2_2; + idx = 2; + } + + if (q0_2 < q3_2) { + q0_2 = q3_2; + idx = 3; + } + + q0_2 = sqrtf(q0_2); + + /* solve for the remaining three components */ + if (idx == 0) { + q1_2 = q0_2; + q2_2 = (R[5] - R[7]) / 4.0F / q0_2; + q3_2 = (R[6] - R[2]) / 4.0F / q0_2; + q0_2 = (R[1] - R[3]) / 4.0F / q0_2; + } else if (idx == 1) { + q2_2 = q0_2; + q1_2 = (R[5] - R[7]) / 4.0F / q0_2; + q3_2 = (R[3] + R[1]) / 4.0F / q0_2; + q0_2 = (R[6] + R[2]) / 4.0F / q0_2; + } else if (idx == 2) { + q3_2 = q0_2; + q1_2 = (R[6] - R[2]) / 4.0F / q0_2; + q2_2 = (R[3] + R[1]) / 4.0F / q0_2; + q0_2 = (R[7] + R[5]) / 4.0F / q0_2; + } else { + q1_2 = (R[1] - R[3]) / 4.0F / q0_2; + q2_2 = (R[6] + R[2]) / 4.0F / q0_2; + q3_2 = (R[7] + R[5]) / 4.0F / q0_2; + } + + /* return values */ + Q[0] = q1_2; + Q[1] = q2_2; + Q[2] = q3_2; + Q[3] = q0_2; +} + +void quat2rot(const float Q[4], float R[9]) +{ + float q0_2; + float q1_2; + float q2_2; + float q3_2; + + memset(&R[0], 0, 9U * sizeof(float)); + + q0_2 = Q[0] * Q[0]; + q1_2 = Q[1] * Q[1]; + q2_2 = Q[2] * Q[2]; + q3_2 = Q[3] * Q[3]; + + R[0] = ((q0_2 + q1_2) - q2_2) - q3_2; + R[3] = 2.0F * (Q[1] * Q[2] - Q[0] * Q[3]); + R[6] = 2.0F * (Q[1] * Q[3] + Q[0] * Q[2]); + R[1] = 2.0F * (Q[1] * Q[2] + Q[0] * Q[3]); + R[4] = ((q0_2 + q2_2) - q1_2) - q3_2; + R[7] = 2.0F * (Q[2] * Q[3] - Q[0] * Q[1]); + R[2] = 2.0F * (Q[1] * Q[3] - Q[0] * Q[2]); + R[5] = 2.0F * (Q[2] * Q[3] + Q[0] * Q[1]); + R[8] = ((q0_2 + q3_2) - q1_2) - q2_2; +}
\ No newline at end of file diff --git a/apps/systemlib/conversions.h b/apps/systemlib/conversions.h index dc383e770..3a24ca9b7 100644 --- a/apps/systemlib/conversions.h +++ b/apps/systemlib/conversions.h @@ -44,6 +44,8 @@ #include <float.h> #include <stdint.h> +#define CONSTANTS_ONE_G 9.80665f + __BEGIN_DECLS /** @@ -56,6 +58,26 @@ __BEGIN_DECLS */ __EXPORT int16_t int16_t_from_bytes(uint8_t bytes[]); +/** + * Converts a 3 x 3 rotation matrix to an unit quaternion. + * + * All orientations are expressed in NED frame. + * + * @param R rotation matrix to convert + * @param Q quaternion to write back to + */ +__EXPORT void rot2quat(const float R[9], float Q[4]); + +/** + * Converts an unit quaternion to a 3 x 3 rotation matrix. + * + * All orientations are expressed in NED frame. + * + * @param Q quaternion to convert + * @param R rotation matrix to write back to + */ +__EXPORT void quat2rot(const float Q[4], float R[9]); + __END_DECLS #endif /* CONVERSIONS_H_ */ |