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INTEGRATED TECH FOR INDUSTRIAL POSITIONING

Integrated Tech for Industrial Positioning | aerospace.honeywell.com 1

IntroductionWe are the world leader in precision IMU technology and

have built the majority of fielded precision IMU products

in the last 50 years. Honeywell has expanded into

commercial / industrial markets and is now shipping two

new non-ITAR IMUs. These IMUs are now available at

industrial pricing through a worldwide sales and distributor

network. The HG1120 is a low cost professional grade

IMU that supports several serial protocols and draws

minimal power. The HG4930 is a very high performance

IMU with a proven rugged design, low cost to integrate,

and competitive pricing. Both devices are suitable for

navigation and control purposes. Whether the platform

is autonomous or manned and whether it operates in

the land, sky, or sea, these IMUs are designed to meet

the platform needs of a range of industries including:

Agriculture, Automotive, Communication, Construction,

Energy, Inspection, Mapping, Marine (Surface & Subsea),

Mining, Robotics, Surveillance, and Transportation.


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Honeywell IMU General Descriptionction

HG1120 and HG4930 Detailed Description

Figure 1. Honeywell Signal and Software

Compensation Timing Diagram

Figure 2. Honeywell Alignment/ Orthogonality Structure

Figure 3. HG1120 Information


Table of contents

Table of tables and figures


Honeywell IMU General Description The Honeywell HG1120 and HG4930 IMUs contain Micro-Electro-Mechanical Systems (MEMS)

which provide the accelerometer and gyroscope function. MEMS gyroscopes have a vibrating

mass and utilize the law of conservation of motion. The motion conservation law means a vibrating

object likes to continue to vibrate in the same plane. When subjected to an angular rate along the

appropriate axis, an out of plane motion is caused (often referred to as Coriolis force). This out of

plane motion is directly proportional to the input angular rate. MEMS accelerometers are based on

Newton’s second law of motion (i.e., Force = Mass x Acceleration). When an acceleration is applied,

the accelerometer sensor measures the force due to the mass and acceleration. This measured

force is directly proportional to the input acceleration. Common to both MEMS gyroscopes and

accelerometers is a manufacturing method that had previously been used for semi-conductor

fabrication. The adaptation of these precision semi-conductor processes enabled low cost

fabrication and smaller sensors.

Individual MEMS accelerometer and gyroscopes sensors of greatly varying capability are available

at low prices from many sources. The necessary sensor integration into an IMU could be done in the

customer system (even by the same processor doing navigation, flight control, or stabilization), but

most systems dedicate a separate microprocessor/architecture to the IMU. The additional value

provided by a separate Honeywell IMU can be summarized as following:

a) Control and stabilization applications

generally require minimum latency and

maximum bandwidth. Navigation applications

use recursive digital filters which require that

all sensors be sampled and compensated

at the same time. Both applications need

high speed sampling and filtering which

are better accomplished at the IMU level

in parallel with the customer system.

b) The compensated sensors should

be physically immune to off axis signals,

magnetics, EMI, vibration, temperature, and

other external environmental effects. A

dedicated IMU provides more opportunity for

an improved mechanical design dedicated

to maximizing sensor performance.

c) More complex calibration

techniques can be applied to the IMU

independent of the customer system. It

would be prohibitively expensive for most

customers to reproduce Honeywell’s world

class calibration and test infrastructure.

d) Keeping the IMU as a module allows the

higher level system to be easily upgraded (better

performance or lower cost). A modular approach

can also help address obsolescence issues as

inertial sensor manufacturers come and go.


A dedicated IMU microprocessor orchestrates the flow of sensor sampling, compensation, and

communication to the customer. Figure 1 shows a typical software frame which includes sensor

sampling, data ready, and serial data transmission. The frame period starts with a data ready signal

transitioning (typically to “Low”). The transition signals that all sensors have been sampled and are

ready for processing. The data ready signal will then transition (typically to high) when data is available

for communication to the customer. Often sensors and compensation are performed at higher rates

than data is transmitted. This is a key advantage of having a dedicated IMU microprocessor because

the IMU can perform additional high speed sampling and filtering in parallel with the customer system

microprocessor. No interaction is required by the system microprocessor.

Figure 1. Honeywell Signal and Software Compensation Timing Diagram

For Honeywell HG1120 and HG4930 IMUs, the processing is completed in under 300 micro-seconds.

The processing time can be variable; therefore, Honeywell eliminates signal jitter by sending data at

a fixed time (300 micro-seconds – See Figure 1). Honeywell devices can be configured to begin the

serial data transmission as soon as processing is complete. Honeywell accomplishes the following

compensations each software data frame:

• Sensor Alignment and Orthogonality

• Gyro Sensitivity to Accelerations

• Scale Factor Accuracy

• Bias Performance

• Lever Arm Compensation

• Scale Factor Linearity

• Coning and Sculling Compensations

• Filtering


No compensation is needed for magnetic signals given that Honeywell MEMS IMUs have no

measurable sensitivity to magnetic fields. Fiber Optic Gyroscope (FOG) based IMUs are known to

provide degraded performance when exposed to magnetic fields. Honeywell calculates individual

unit parameter compensations using precision multi-axis rate table and thermal chamber tests.

Honeywell’s >50 years of inertial sensor development and compensation techniques assure correctly

designed and implemented IMU algorithms. Sensor alignment and orthogonality compensation

have immediate consequences if not done correctly: Large signals on one axis (for example –

gravity or rapid platform turning rates) can drown out real off-axis signals. Honeywell specifies and

measures the full set of alignment/orthogonality matrices (see Figure 2) necessary to implement

a proper Kalman filter type navigation solution. Frame definition is required between the customer

navigation frame, the Honeywell IMU, and the mounting structure.

Figure 2. Honeywell Alignment/Orthogonality Structure


Honeywell supports both navigation and control/stability applications by providing two types

of messaging – Control data (filtered) and Navigation data (incremental angles and velocity).

Honeywell’s HG1120 and HG4930 IMU filtered data is sampled and calculated at 1800 Hz. The

Honeywell provided filters take into account sensor characteristics and internal isolation. The

defined bandwidth is also inclusive of transmission time to the customer.

When Honeywell IMUs are integrated into a navigation solution, the algorithms responsible for

integrating the incremental outputs require that all linear and rotational dynamics experienced by

the vehicle be precisely integrated; therefore, minimal filtering is applied to the IMU incremental

outputs as filtering suppresses important dynamic content. For incremental outputs, the sensor

information is compensated at the 1800 Hz sample data rate and then integrated to a lower data

rate (typically 100 Hz). This integration consists of summing the information over the data rate time

period and compensating the incremental outputs for coning and sculling. The coning and sculling

correction allows the incremental angle and velocity information to be directly integrated by the

customer without loss of integrity. Incremental angle and incremental velocity precisely capture all

the vehicle dynamics required for navigation.

Incremental outputs are provided to the customer relative to the data rate. The incremental angle

units are degrees or equivalently . The incremental velocity units are meters/second or

equivalently . To obtain angular rate and acceleration, multiply incremental data by

the data rate.

degreessecond x Hz

meterssec x sec x Hz


HG1120 and HG4930 Detailed DescriptionThe Honeywell HG1120 and HG4930 IMUs have similar messaging, specification structures, and

interfaces. Both IMUs allow interfacing through a readily available low cost dual row connector.

Communication is a simple RS422 asynchronous serial interface. The units are powered by +5

VDC. Both the HG1120 and HG4930 messaging structure include dual data frequency outputs

that provide for both incremental and control information without additional programming by the

customer. The dual data rates through a single port are achieved by using distinguishing message

identification headers. The HG4930 data rate is fixed at 600 Hz for filtered outputs and 100 Hz

for incremental outputs. The HG1120 also has dual data rates but in addition to 600 Hz/100 Hz

outputs, also has an option for 1800 Hz control/300 Hz incremental outputs. The data rates for the

HG1120, in addition to filtering options, are easily selectable via four discrete input pins.

The HG1120 has a full scale angular rate output of 500 °/second while the HG4930 has a full

scale angular rate output of 200 °/second (400 °/second is available upon request). The HG1120

acceleration range is -16 to +16 g’s while the HG4930 has a range of -20 to + 20 g’s. The HG1120

also includes magnetometer outputs which the customer may calibrate and use for heading

determination. Summary HG1120 and HG4930 performance information is shown in Figures 3 and

4. Detailed manuals are available on the Honeywell web sites (aerospace.honeywell.com/HG4930

and aerospace.honeywell.com/HG1120).


HG1120 IMU STANDARD MODELS TYPICAL PERFORMANCE- STABLE ROOM TEMPERATURE

VariantGyro Bias

Repeatability (°/hr 1ơ)

Gyro Bias In-run Stability (°/hr

1ơ)

ARW (°/√hr)

Accel Bias Repeatability

(mg 1ơ)

AccelBias In-run Stability¹ (mg 1ơ)

VRW (m/s/√hr)

HG1120CA50 260 10 0.3 5 0.03 0.050

HG1120BA50 520 24 0.4 10 0.05 0.015

HG1120AA50 780 48 0.5 15 0.08 0.025

HG1120 IMU KEY CHARACTERISTICS

Volume/Size 29cm³ (1.7in³), 47.0 x 43.9 x 14.1 mm

Weight <70g (0.15 lbs)

Power Consumption 0.4 Watts

Operating Temperature Range -40°C to 85°C

Data Rate Up to 300 Hz (Guidance) and 1800 Hz (Control)- user configurable

Gyroscope Operating Range Up to 500 deg/sec

Accelerometer Operating Range + / - 16g

Supply Voltage +3.0 – 5.5VDC



HG4930 IMU KEY CHARACTERISTICS

Volume/Size 82 cm³ (5 in³), 65 x 51 x 35.5 mm

Weight 140g, (0.3 lbs)

Power Consumption <2 Watts

Operating Temperature Range -54°C to 85°C

Data Rate 100 Hz (Guidance) and 600 Hz (Control)

Gyroscope Operating Range Up to 200 deg/sec ( < 400 deg/sec available upon request)

Accelerometer Operating Range +/- 20 g

Supply Voltage +5VDC

HG4930 IMU TYPICAL PERFORMANCE OVER FULL OPERATING TEMPERATURE RANGE

VariantGyro Bias

Repeatability (°/hr 1ơ)

Gyro Bias In-run Stability (°/hr 1ơ)

ARW (°/√hr)

Accel Bias Repeatability

(mg 1ơ)

AccelBias In-run Stability¹ (mg 1ơ)

VRW (m/s/√hr)

HG4930CA51 7 0.25 0.04 1.7 0.025 0.03

HG4930BA51 10 0.35 0.05 2.0 0.050 0.04

HG4930AA51 20 0.45 0.06 3.0 0.075 0.06


Edit Text Variable, Header Document Title | www.honeywellaidc.com 10

N40-2065-000-000 | 09/17© 2017 Honeywell International Inc.

For more informationaerospace.honeywell.com

Contact usFor more information, email [email protected]

or contact us on our website aerospace.honeywell.com

Honeywell Aerospace 1944 East Sky Harbor Circle

Phoenix, Arizona 85034

+1 (800) 601 3099

aerospace.honeywell.com

Drew Karnick - AuthorStaff Applications Engineer

Inertial Sensors and Navigation

Non-Aero / Non-Defense Applications

Honeywell Aerospace

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