Basic Toolkit › Signal Processing components

imu_to_pose6D

Converts the orientation quaternion of an IMU or AHRS to pose6D, whatever the sensor.

Processing

• The quaternion is normalized and converted to a rotation matrix, then to roll, pitch and yaw (R = Rz(yaw) Ry(pitch) Rx(roll)).
• With reference_frame = NED the rotation is converted to world ENU and body FLU: the roll keeps its sign, the pitch changes its sign and yaw = 90 deg - heading.
• The output carries the timestamp of the input.
• Sensor fusion is not done here: use a sensor that outputs its orientation, or imu_orientation_estimator.

Data format

• quaternion must have 4 elements; other sizes stop the component with an error.
• pose6D is [0, 0, 0, roll, pitch, yaw] in m and rad. The translation is always 0 because an IMU cannot measure a position.

Notes

• A sample that is not finite, or with a norm below 1e-6, is skipped; a warning is reported once.
• The output is the orientation of the IMU itself. Apply the mounting of the IMU, from Sensor Calibration File Parser, where the orientation is used.
• The reference of the yaw depends on the sensor; a 6-axis sensor drifts in yaw.

References

• [1] T. Foote and M. Purvis, REP 103: Standard Units of Measure and Coordinate Conventions, ROS Enhancement Proposals. https://www.ros.org/reps/rep-0103.html — Used for: world ENU and body FLU axes, units.
• [2] REP 145: Conventions for IMU Sensor Drivers, ROS Enhancement Proposals. https://www.ros.org/reps/rep-0145.html — Used for: conventions of the orientation given by IMU drivers.
• [3] sensor_msgs/Imu message definition, ROS common_msgs. https://docs.ros.org/en/api/sensor_msgs/html/msg/Imu.html — Used for: xyzw order of the quaternion.

Properties

Outputs

Inputs