Download AHRS Interface Control Document

AHRS Interface Control Document
6.2. Output Data Formats of the Inertial LabsTM AHRS in the Operating
Modes
The next output data formats are available in the “Continuous” and “On
Request” operating modes:
 Full Output Data;
 Quaternion of Orientation;
 Orientation + Sensor Outputs;
 NMEA Output (since AHRS firmware version 4.9.2)
The default is “Orientation + Sensor Outputs” data format. It provides the
AHRS output in the form of 3 orientation angles (heading, pitch and roll)
and calibrated outputs of the 9 sensors (gyros, accelerometers,
magnetometers) that give information about current angular rate, linear
acceleration of the AHRS and components of outer magnetic field along
the AHRS measurement axes (see Fig.1.2).
More correctly, these 9 sensors output are integrated angular rate, linear
acceleration (specific force), magnetic field increments. In the AHRS output
these increments are divided by time step of data output so they may be
interpreted as average angular rates, linear acceleration and magnetic field
for cycle of data output. On the other hand, incremental sensor data are
good for the AHRS using as IMU (inertial measurement unit).
The “Quaternion of Orientation” data format gives quaternion
presentation of an object orientation in addition to 3 orientation angles.
Usually the “Full Output Data” format is used by the AHRS developers for
full control of calculations in the AHRS microprocessor. Also this format
can be used by user at any troubles to get full data from the AHRS for next
sending them to developers.
Structure of the AHRS output in above output data formats corresponds to
the Table 6.2 where payload depends on chosen output data format. Table
6.4 – Table 6.6 show these payloads where is denoted:
word = unsigned 2 byte integer;
sword = signed 2 byte integer.
Inertial Labs, IncTM
Address: 13800 Coppermine Road, Suite 300, Herndon, VA 20171, USA
Tel: +1 (703) 880-4222, Fax: +1 (703) 935-8377 Website: www.inertiallabs.com
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