INTEGRATED TECH FOR INDUSTRIAL POSITIONING

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1 INTEGRATED TECH FOR INDUSTRIAL POSITIONING

2 Integrated Tech for Industrial Positioning aerospace.honeywell.com 1 Introduction We 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.

3 Integrated Tech for Industrial Positioning aerospace.honeywell.com 2 Table of contents 3 Honeywell IMU General Descriptionction 7 HG1120 and HG4930 Detailed Description Table of tables and figures Figure 1. Honeywell Signal and Software Compensation Timing Diagram Figure 2. Honeywell Alignment/ Orthogonality Structure Figure 3. HG1120 Information Figure 3. HG4930 Information

4 Integrated Tech for Industrial Positioning aerospace.honeywell.com 3 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.

Integrated Tech for Industrial Positioning aerospace.honeywell.com 4 A dedicated IMU microprocessor orchestrates the flow of sensor sampling, compensation, and communication to the customer.

The transition signals that all sensors have been sampled and are ready for processing.

5 Integrated Tech for Industrial Positioning aerospace.honeywell.com 4 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

6 Integrated Tech for Industrial Positioning aerospace.honeywell.com 5 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

7 Integrated Tech for Industrial Positioning aerospace.honeywell.com 6 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 equivalently the data rate. meters sec x sec x Hz degrees second x Hz. The incremental velocity units are meters/second or. To obtain angular rate and acceleration, multiply incremental data by

8 Integrated Tech for Industrial Positioning aerospace.honeywell.com 7 HG1120 and HG4930 Detailed Description The 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).

9 Integrated Tech for Industrial Positioning aerospace.honeywell.com 8 HG1120 IMU STANDARD MODELS TYPICAL PERFORMANCE- STABLE ROOM TEMPERATURE Variant Gyro 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) HG1120CA HG1120BA HG1120AA 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 VDC Figure 3. HG1120 Information

10 Integrated Tech for Industrial Positioning aerospace.honeywell.com 9 Variant HG4930 IMU TYPICAL PERFORMANCE OVER FULL OPERATING TEMPERATURE RANGE Gyro 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) HG4930CA HG4930BA HG4930AA 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 Figure 4. HG4930 Information

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12 Drew Karnick - Author Staff Applications Engineer Inertial Sensors and Navigation Non-Aero / Non-Defense Applications Honeywell Aerospace For more information aerospace.honeywell.com Contact us For more information, imu.sales@honeywell.com or contact us on our website aerospace.honeywell.com Honeywell Aerospace 1944 East Sky Harbor Circle Phoenix, Arizona (800) aerospace.honeywell.com N / Honeywell International Inc.

HG4930 INERTIAL MEASUREMENT UNIT (IMU) Installation and Interface Manual

HG4930 INERTIAL MEASUREMENT UNIT (IMU) Installation and Interface Manual HG4930 Installation and Interface Manual aerospace.honeywell.com/hg4930 2 Table of Contents 4 5 6 10 11 13 13 Honeywell Industrial