Lord MicroStrain 3DM-GX4-25 User manual

LORD USERMANUAL
3DM-GX4-25™
Miniature Attitute Heading Reference System (AHRS)

© 2014 LORDCorporation
MicroStrain®Sensing Systems
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Suite 102
Williston, VT 05495
United States of America
Phone: [phone]
Toll Free: 800-449-3878
Fax: [phone]
http://www.microstrain.com
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Copyright © 2014 LORD Corporation
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GX3®, 3DM-GX4™, 3DM-DH®, 3DM-DH3™, EmbedSense®, MicroStrain®, and Little Sensors, Big Ideas.®are
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Document 8500-0047 Revision A
Subject to change without notice.

3DM-GX4-25™Attitute Heading Reference System User Manual
Table of Contents
1. System Overview 6
2. Sensor Overview 7
2.1 Components 8
2.2 Interface and Indicators 9
3. Basic Setup and Operations 10
3.1 Software Installation 11
3.2 System Connections 12
3.3 Software Interface 13
3.3.1 Interactive Help Menu 13
3.4 Sensor Communication 14
3.5 Sensor Settings 15
3.5.1 Saving Configurations 17
3.6 Data Monitoring and Recording 18
3.7 Viewing Data 21
4. Sensor Measurements 22
4.1 Direct Sensor Measurements (IMU Outputs) 23
4.2 Computed Outputs (Estimation Filter/AHRS) 25
4.3 Sensor Reference Frames 28
4.3.1 Geodetic Frame 28
4.3.2 NorthEast Down (NED) Frame 29
4.3.3 Sensor Frame 30
4.3.4 Platform Frame 31
5. Performance Optimization 33
5.1 Magnetometer Calibration 33

3DM-GX4-25™Attitute Heading Reference System User Manual
5.2 Gyroscope Bias 36
5.3 Heading Drift and Compensation 37
5.4 Angular Rate and Acceleration Limits 38
5.5 Bandwidth 38
5.6 Platform Frame Transformation 38
5.7 Estimation Filter Operation 38
5.8 Estimation Filter Convergence 40
5.8.1 Initial Convergence 40
5.8.2 Bias Convergence 40
5.8.3 Output Uncertainty 40
5.9 Vibration Isolation 41
5.10 IMU Sensor Calibration 41
5.11 Temperature Compensation 41
6. Sensor Installation 42
6.1 Sensor Mounting 42
7. OEMSystemIntegration 43
7.1 DataCommunications Protocol (DCP) 43
7.1.1 Packet Builder 44
7.1.2 Sensor Direct Mode 45
7.2 Sensor Wiring 46
7.3 Sampling on Start-up 47
7.4 Connecting to a Datalogger 47
7.5 Using Wireless Adapters 47
8. Troubleshooting 48
8.1 Troubleshooting Guide 48
8.2 Repair and Calibration 52

3DM-GX4-25™Attitute Heading Reference System User Manual
8.3 Technical Support 53
9. Maintenance 54
10. Parts and Configurations 55
10.1 Standard Configurations 55
10.2 Accessories 57
10.3 Warranty Information 58
10.4 Sales Support 59
11. Safety Information 60
12. References 61
12.1 Reference Documents 61
12.2 Glossary 62

3DM-GX4-25™Attitute Heading Reference System User Manual System Overview
6
1. System Overview
The LORD MicroStrain®3DM-GX4™family of industrial grade inertial sensors provides a wide
range of triaxial orientation measurements and computed navigation solutions. In all models, the
Inertial Measurement Unit (IMU) includes direct measurement of acceleration, angular rate, and
atmospheric pressure. Sensor measurements are processed through an Extended Kalman Filter
(EKF) to produce high accuracy computed outputs. The computed outputs vary between models
and include: pitch and roll in the 3DM-GX4-15™model, the full attitude solution (pitch, roll, and
yaw) in the 3DM-GX4-25™AHRS model, and the full PVA (position, velocity and attitude) solution
in the 3DM-GX4-45™GPS-INS model. The Kalman filter provide Adaptive EKF technologies to
compensate for magnetic and linear acceleration anomalies, as applicable to the model. It also
provides sensor bias tracking, auto-zero update options (ZUPT), and user adjustable sensor noise
factors. All sensors are fully temperature compensated and calibrated over the full operating
temperature range
The use of Micro-Electro-Mechanical System (MEMS) technology allows for small, lightweight
devices. Sensors are integrated into customer systems using serial communication protocols such
as RS232 and USB. The LORD MicroStrain ®MIPMonitor software can be used for device
configuration, real time measurement monitoring, and data recording. The LORD MicroStrain®
MIPData Communications Protocol that is used to communicate with LORD MicroStrain®inertial
sensors is also available for users who want to develop customized software solutions. Because of
the unified set of commands across the sensor family, it is easy to migrate code from one inertial
sensor to another.
Common applications of LORD MicroStrain ®inertial sensor products include vehicle health
monitoring, platform stabilization, down- hole and drilling operations, and inertial navigation
systems such as unmanned air and ground vehicles and personal navigation systems.

3DM-GX4-25™Attitute Heading Reference System User Manual Sensor Overview
7
2. Sensor Overview
The 3DM-GX4-25™is a high-performance, miniature Attitude Heading Reference System
(AHRS) that combines micro inertial sensors for use in a wide range of industrial grade
applications such as unmanned vehicle navigation, robotic control, platform stabilization, motion
tracking and analysis, vehicle health monitoring, and device aiming.
The 3DM-GX4-25™utilizes the strengths of integrated multi-axis gyroscopes, accelerometers,
and magnetometers in combination with temperature, and pressure readings to provide high
accuracy attitude (including heading), and inertial measurements. Each of the integrated sensors
is especially good at certain tasks, and it is the weighted combination of their outputs that provides
the best estimations for attitude. All sensor measurements are temperature compensated and are
mathematically aligned to an orthogonal coordinate system. The combination of sensors,
environmental compensation and dual on-board processing with an Adaptive Kalman Filter (AKF)
allow the 3DM-GX4-25™to perform well in a wide variety of applications that require low noise,
drift, gain, and offset errors. Uncertainty monitoring, and bias estimation outputs are available, and
settings for sensor filtering, sensor noise, sensor bias, and more offer many adjustments for
specific application needs.
The 3DM-GX4-25™communicates through a serial communications cable and is monitored by a
host computer. Sensor measurements and computed outputs can be viewed and recorded with
the LORD MicroStrain®MIPMonitor software that is provided with system starter kits, and also
available as a free download from the LORD MicroStrain®website. Alternatively, users can write
custom software with the LORD MicroStrain®open source data communication protocol. The
data is time-aligned and available by either polling or continuous stream.
Figure 1 - 3DM-GX4-25™Sensor

3DM-GX4-25™Attitute Heading Reference System User Manual Sensor Overview
8
2.1 Components
The 3DM -GX4 -25™can be purchased by itself or in a starter kit that includes everything
needed to begin using it. The starter kits include the 3DM-GX4-25™inertial sensor, a serial
communications cable (either RS232 or USB), a power supply with country plug adapter
(RS232 kits only), and all software, drivers, and documentation. This manual covers all items
included in the starter kits. For a complete list of available configurations, accessories,
additional system products and ordering information see Parts and Configurations on page 55.
Item Description Quantity
A3DM-GX4-25™Inertial Sensor 1
BCommunications cable (USB or RS232) 1
CPower supply and country plug adapters (for RS232 only) 1
-- MIPMonitor Software Suite 1
-- User Manual, Quick Start Guide and Calibration Certificate 1
Table 1 - Components List

3DM-GX4-25™Attitute Heading Reference System User Manual Sensor Overview
9
2.2 Interface and Indicators
The 3DM-GX4-25™sensor interface is a dual use communications and power input connector.
The sensor is mounted using the mounting and alignment holes as needed (see Sensor
Mounting on page 42).
The indicators on the 3DM - GX4 - 25 ™include a device status indicator and the device
information label. Table 2 - Indicator Behaviors describes the basic status indicator behavior.
The device information label includes the sensor frame diagram (axis orientation) which will be
critical during device installation (see Sensor Frame on page 30).
Figure 2 - Interface and Indicators
Indicator Behavior Device Status
device status
indicator
OFF no power applied
rapid flash streaming data
slow pulse idle mode, awaiting commands
Table 2 - Indicator Behaviors

3DM-GX4-25™Attitute Heading Reference System User Manual Basic Setup and Operations
10
3. Basic Setup and Operations
Do not bring the inertial sensor into contact or close proximity
with magnets. Magnets may disrupt the sensor operation and
cause magnetization of internal components, which can
affect magnetometer performance. If magnetization is
suspected, use a degaussing tool to demagnetize.
To acquire sensor measurements and computed outputs, the 3DM-GX4-25™is used with a host
computer capable of serial communication, and a software interface. The LORD MicroStrain®
MIPMonitor software is provided with the system and includes all functions needed for sensor
configuration and data acquisition. Users may also utilize the LORD MicroStrain ®MIPData
Communications Protocol to write custom software applications with expanded or specific feature
sets needed for the application. MIPMonitor includes a message building tool that can be used to
streamline this process. For more information see OEMSystemIntegration on page 43.
In this section hardware and software setup is described, including an overview of the MIPMonitor
software menus required to configure a sensor and begin data acquisition. It is intended as a quick
start guide and is not a complete demonstration of all system or software features and capabilities.
Figure 3 - Acquiring Sensor Data with MIPMonitor