3DM-CX5-GNSS/INS
User Manual
17
4.1
Direct Sensor Measurements (IMU Outputs)
The sensors in an Inertial Navigation System (INS), from which measurements for navigation and
orientation are obtained, are collectively known as the Inertial Measurement Unit (IMU). These sensors
are arranged on the three primary axes (x, y, and z) to sense angular rate, acceleration, and the local
magnetic field. The gyroscopes are used to adjust the current attitude estimate when an angular rate is
sensed. The accelerometers sense gravity as well as linear acceleration. The magnetometers sense
the Earth’s magnetic field along with local magnetic anomalies. All measurements are temperature-
compensated and are mathematically aligned to an orthogonal coordinate system.
The IMU sensors can be read directly to report stand alone inertial measurements or computed
measurements. Because the sensor system is digital, the analog voltage readings from the sensors are
converted into a digital equivalent value based on the volt-to-bit scale of the internal analog-to-digital
voltage converter. In the MIP Monitor software the conversion values are not configurable, but there
are user-settable options for how the measurement is made. These settings are available at: Settings >
Device > IMU (tab). With the Help window open (accessed with the Help button), mousing over
context-sensitive settings provides a detailed explanation of the setting (
Figure 15. IMU Settings
