HG1120 inertial sensing unit

The Honeywell HG1120 is a MEMS inertial measurement unit made by Honeywell Aerospace for navigation, stabilisation and control. It contains MEMS gyroscopes, accelerometers and magnetometers in one small housing, and it supplies motion data to a host system that performs attitude, heading or position estimation.

The sensor set is specified as follows. The gyroscopes have a range of +/-500 deg/s with an in-run bias stability of 10 deg/hr. The accelerometers have a range of 16 g with an in-run bias stability of 0.03 mg. The magnetometers cover +/-16 gauss. In-run bias stability describes how much the sensor output drifts during operation, so for an integrator it sets how quickly an attitude solution degrades between corrections from GNSS, a barometer or a magnetometer. The output rate is 1800 Hz, which is high enough for flight-control loops and for payload stabilisation.

An internal environmental isolation system attenuates unwanted inputs found in real installations, such as vibration, so the unit can be installed on a vehicle structure without a separate damping mount in many cases. Honeywell describes the isolation and other design features as the basis for the ruggedness of the unit. Operating temperature ranges from -40 C to 85 C.

Electrical integration is simple. The supply is 3 to 5.5 VDC and the power consumption is 0.4 W. The digital interfaces are RS-422 and CAN. The outputs are fully compensated incremental (delta) values that can be passed directly into position and attitude computation, and a control message is used to optimise latency and bandwidth. The unit weighs 54 g and its outline dimensions are 47 mm, 43.9 mm and 14.1 mm, which makes it suitable for small payload bays and avionics boards.

The HG1120 is offered in several performance grades. Honeywell states that it is not ITAR controlled and that its Export Control Classification Number is 7A994, which is relevant for export planning by OEMs.

Honeywell lists agriculture, autonomous underwater vehicles, industrial equipment, robotics, survey and mapping, stabilised platforms, transportation, UAVs and UGVs as target markets. Typical uses on an unmanned aircraft are the inertial input for an autopilot or a navigation filter, the stabilisation of a gimbal or antenna, and motion compensation for mapping and survey payloads.