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Lord MicroStrain 3DM-GX4-45 User Manual

Miniature gps-aided inertial navigation system (gps/ins
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LORD USER MANUAL
™
3DM-GX4-45
Miniature GPS-Aided Inertial Navigation System (GPS/INS)

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Summary of Contents for Lord MicroStrain 3DM-GX4-45

  • Page 1 LORD USER MANUAL ™ 3DM-GX4-45 Miniature GPS-Aided Inertial Navigation System (GPS/INS)
  • Page 2 © 2014 LORD Corporation ® MicroStrain Sensing Systems 459 Hurricane Lane Suite 102 Williston, VT 05495 United States of America Phone: 802-862-6629 Toll Free: 800-449-3878 Fax: 802-863-4093 http://www.microstrain.com sensing_support@LORD.com sensing_sales@LORD.com Copyright © 2014 LORD Corporation ™ ™ ™ ® ® ® ™...

  • Page 3: Table Of Contents

    ™ ™ 3DM-GX4 Inertial Navigation System User Manual Table of Contents System Overview Sensor Overview 2.1 Components 2.2 Interface and Indicators Basic Setup and Operations 3.1 Software Installation 3.2 System Connections 3.3 Software Interface 3.3.1 Interactive Help Menu 3.4 Sensor Communication 3.5 GPS Link 3.6 Sensor Settings 3.6.1 Saving Configurations...
  • Page 4 ™ ™ 3DM-GX4 Inertial Navigation System User Manual Performance Optimization 5.1 Magnetometer Calibration 5.2 Gyroscope Bias 5.3 Heading Drift and Compensation 5.4 Angular Rate and Acceleration Limits 5.5 Bandwidth 5.6 Platform Frame Transformation 5.7 GPS Parameters 5.8 GPS Antenna Offset 5.9 Vehicle Dynamics Mode 5.10 Estimation Filter Operation 5.11 Estimation Filter Convergence 5.11.1 Initial Convergence...
  • Page 5 ™ ™ 3DM-GX4 Inertial Navigation System User Manual 7.2 Sensor Wiring 7.3 Alternate GPS Equipment 7.3.1 GPS External Receiver 7.4 Sampling on Start-up 7.5 Connecting to a Datalogger 7.6 Using Wireless Adapters Troubleshooting 8.1 Troubleshooting Guide 8.2 Repair and Calibration 8.3 Technical Support Maintenance Parts and Configurations 10.1 Standard Configurations...

  • Page 6: System Overview

    Sensors are integrated into customer systems using serial communication protocols such ® as RS232 and USB. Each device comes with the LORD MicroStrain MIP Monitor software that can be used for device configuration, real time measurement monitoring, and data recording. The ®...

  • Page 7: Sensor Overview

    GPS satellite links. Sensor measurements and ® computed outputs can be viewed and recorded with the LORD MicroStrain MIP Monitor software that is provided with system starter kits or available as a free download from the LORD ®...

  • Page 8: Components

    Sensor Overview User Manual 2.1 Components ™ The 3DM-GX4-45 can be purchased by itself or in a starter kit that include everything needed ™ to begin using it. The starter kits include the 3DM - GX4 - 45 inertial sensor, a serial...

  • Page 9: Interface And Indicators

    Sensor Overview User Manual 2.2 Interface and Indicators ™ The 3DM-GX4-45 sensor interfaces include a dual use communications and power input connector and a GPS antenna port. The sensor is mounted using the mounting and alignment holes as needed (see Sensor Mounting on page 47).

  • Page 10: Basic Setup And Operations

    To acquire sensor measurements and computed outputs, the 3DM-GX4-45 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 ®...

  • Page 11: Software Installation

    ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 3.1 Software Installation NOTE The MIP Monitor Software Suite includes hardware drivers required for all ™ 3DM-GX4 sensors.  Sensors will not be recognized without these drivers. To install MIP Monitor  Software Suite on the host computer, complete the following steps: 1.

  • Page 12: System Connections

    To acquire sensor data the following components are needed: 3DM - GX4 - 45 sensor, communication cable, power cable, as applicable for RS232 communications, GPS antenna, GPS antenna adapter cable, and a host computer with access to the data acquisition software, ® such as LORD MicroStrain MIP Monitor. Figure 5 - System Connections...

  • Page 13: Software Interface

    ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 3.3 Software Interface The MIP Monitor software includes a main window with system information and menus, a device settings window ( see Sensor Settings on page 15 ), and several data monitoring windows (see Data Monitoring and Recording on page 18).

  • Page 14: Sensor Communication

    ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 3.4 Sensor Communication Once power has been applied to the sensor, it is on. The sensor selects the appropriate serial communication (USB or RS232) on power- up based on which cable is connected. If the hardware drivers have been installed, communication can be established using the MIP Monitor software interface.

  • Page 15: Gps Link

    ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 3.5 GPS Link NOTE The GPS antenna requires unobstructed line of sight with the sky in order to achieve communication with the GPS  satellites. Communication between the GPS receiver and GPS satellites is initiated when the 3DM-GX4- ™...
  • Page 16 ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 1. The following describes the Device Settings interface: a. Main menu tabs: The main tabs break up the setting into broad functional groups for the types of measurement available. For the 3DM- ™...

  • Page 17: Saving Configurations

    ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 3.6.1 Saving Configurations Sensor settings are saved temporarily in the device memory by selecting the OK button in the Device Setup window. To save the settings for future use, select Settings > Save Current Settings from the main window (Figure 10 - Save Sensor Settings).

  • Page 18: Data Monitoring And Recording

    ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 3.7 Data Monitoring and Recording NOTE During viewing and recording, only the outputs that are selected in the Message Format tabs in the Device Setup menu are displayed and recorded (see Sensor Settings on page 15).
  • Page 19 ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual There are several data monitoring views available depending on what measurements are desired for monitoring and recording. Each view corresponds to one of the main categories in ™ the Device Settings window.
  • Page 20 Microsoft Excel NOTE If the data is recorded in Binary format it will require a translation program that ® utilizes the LORD MicroStrain MIP Data Communications Protocol to make it user-readable. Figure 13 - Record Data 5.

  • Page 21: Viewing Data

    ™ ™ 3DM-GX4 Inertial Navigation System Basic Setup and Operations User Manual 3.8 Viewing Data Acquired data is stored in either Binary (.bin) or Comma Separated Values (.CSV) format, depending on what was selected at the initiation of data recording. The files can be found in the directory specified at that time or in the default directory on the host computer desktop.

  • Page 22: Sensor Measurements

    User Manual Sensor Measurements ™ The 3DM-GX4-45 block diagram (Figure 15 - 3DM-GX4-45™ Block Diagram ) describes its primary hardware components and internal configuration. Integrated Micro-Electro-Mechanical ™ System (MEMS) sensors within the 3DM - GX4 - 45 are collectively known as the Inertial Measurement Unit (IMU) and include tri-axial gyroscopes (gyros), tri-axial accelerometers, tri-axial magnetometers, and a pressure altimeter.

  • Page 23: Direct Sensor Measurements (Imu Outputs)

    ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual 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 know 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 .
  • Page 24 Sensor Measurements User Manual ™ Table 4 - IMU Measurements lists the IMU measurements available for the 3DM-GX4-45 Engineering units are temperature compensated, A/D bit readings are not. ™ Calibration of the 3DM-GX4-45 IMU sensors is performed at the factory when the device is manufactured.

  • Page 25: Global Positioning System (Gps) Outputs

    ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual 4.2 Global Positioning System (GPS) Outputs ™ The Global Positioning System (GPS) receiver in the 3DM - GX4- 45 uses its own GPS positioning engine to process GPS metrics from a minimum of four satellites. Accuracy and reliability of the GPS readings are highly dependent on the quality of the satellite fix, and information is provided to determine an appropriate confidence level.
  • Page 26 ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual Measurement Units Description position reported by GPS module only, degrees (position) Position (LLH) expressed in Latitude, Longitude, and Height meters (accuracy) (LLH) with accuracy estimation meters/second velocity measurement reported by GPS module Velocity (NED) (velocity) only, with reference to North, East, Down...

  • Page 27: Computed Outputs (Estimation Filter/Pva)

    User Manual 4.3 Computed Outputs (Estimation Filter/PVA) ™ The computed outputs are measurements from the 3DM-GX4-45 IMU sensors and GPS receiver that are processed through an Extended Kalman Filter (EKF) algorithm. Together they produce high accuracy position, velocity, and attitude (PVA) outputs at high data rates. Refer to Table 6 - Estimation Filter Outputs for a complete list of outputs.
  • Page 28 ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual EF outputs can be viewed and recorded with bias, scale, and uncertainty metrics. Other information, such as GPS time and device status, are available for reference ( Table 6 - Estimation Filter Outputs).
  • Page 29 ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual Measurement Units Description gravity estimate from accelerometer read- Gravity Vector meter/second ings with reference to either the sensor or vehicle frame (depending on settings) local magnitude of gravity with reference WSG-84 Local meter/second to the WSG-84 model and readings from...

  • Page 30: Sensor Reference Frames

    ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual 4.4 Sensor Reference Frames 4.4.1 Geodetic Frame The World Geodetic System is the standard for cartography and navigation. The latest ™ revision, WGS84, is the reference coordinate system for GPS, and the 3DM- GX4-45 reports position using this coordinate frame.

  • Page 31: North East Down (Ned) Frame

    For most applications, this assumption is valid and provides a more intuitive reference frame for expressing velocity and attitude information than a global frame. ™ The 3DM-GX4-45 reports velocity in this frame and attitude with respect to this frame. Figure 20 -...

  • Page 32: Sensor Frame

    ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual 4.4.3 Sensor Frame The sensor frame is indicated on the top of the device and is oriented such that the x-axis vector is parallel with the long side of the sensor and points toward the sensor connector, the y-axis is 90°...

  • Page 33: Platform Frame

    User Manual 4.4.4 Platform Frame ™ The 3DM-GX4-45 includes the option to define an orientation transformation and offset distance from the sensor frame to the platform the sensor is mounted to. This is useful when the sensor cannot be mounted in the same location or orientation as the desired reference point on the platform frame.
  • Page 34 ™ ™ 3DM-GX4 Inertial Navigation System Sensor Measurements User Manual In the MIP Monitor software the transformation and offset settings are entered in the Settings > Device > Estimation Filter > Mounting > Mounting Orientation and Mounting Offset fields (Figure 23 - Platform Frame Settings).

  • Page 35: Performance Optimization

    However, often these sources are hard to avoid or are hidden. ™ When using the 3DM-GX4-45 magnetometer to aid in heading estimations, a field calibration of the magnetometer after final installation is highly recommended. This can be accomplished ®...
  • Page 36 ™ ™ 3DM-GX4 Inertial Navigation System Performance Optimization User Manual Figure 24 - Collect Calibration Data 5. When all possible rotations are completed, select Stop Collecting and then select Save Data to save the calibration data points (Figure 25 - End Calibration).
  • Page 37 ™ ™ 3DM-GX4 Inertial Navigation System Performance Optimization User Manual choice. If there are enough points in all dimensions, the Ellipsoid Fit may be better. Generally, if the Spherical and Ellipsoid Fits are close in the mean diameter, then the Ellipsoid Fit will be the best choice.

  • Page 38: Gyroscope Bias

    ™ ™ 3DM-GX4 Inertial Navigation System Performance Optimization User Manual 5.2 Gyroscope Bias Gyroscope biases (offsets) can be zeroed out to set a baseline value for the static home position and conditions in the application. This should be done after sensor installation. To set the gyroscope baseline, place the sensor or sensor platform in the desired home position.

  • Page 39: Heading Drift And Compensation

    ™ ™ 3DM-GX4 Inertial Navigation System Performance Optimization User Manual Heading Drift and Compensation There are four options for the heading reference source: GPS velocity, the magnetometer, an external reference, or none. If the setting is an external reference, the user has to provide a heading reference (for example, see GPS External Receiver on page 54).

  • Page 40: Angular Rate And Acceleration Limits

    5.7 GPS Parameters ™ The GPS receiver used in the 3DM-GX4-45 has an altitude limitation of 50 kilometers and a speed limitation of 500 meters/second in accordance with the United States International Treaty in Arms Regulation (ITAR) restrictions.

  • Page 41: Gps Antenna Offset

    5.8 GPS Antenna Offset ™ GPS antenna offset is the distance of the antenna for the GPS receiver in the 3DM-GX4-45 This offset effects the accuracy of the GPS position readings. The MIP Monitor allows entry of the offset in the Settings > Device > Estimation Filter > Mounting > Antenna Offset (Figure 29 - GPS Antenna...

  • Page 42: Vehicle Dynamics Mode

    In the MIP Monitor software this setting is found in the Settings > Device > Estimation Filter > EF Options > Vehicle Dynamics Mode menu (Figure 30 - Vehicle Dynamics Setting). ™ Refer to the 3DM-GX4-45 Data Communications Protocol (DCP) for more information about this setting. Figure 30 - Vehicle Dynamics Setting...

  • Page 43: Estimation Filter Operation

    (no translation or rotation between the two) they can be compensated for by performing ™ a hard iron and/or soft iron calibration of the magnetometers internal to the 3DM-GX4-45 see Magnetometer Calibration on page 35 ). The hard iron calibration compensates for magnetic effects that cause offsets in the magnetic field (additive effects).
  • Page 44 ™ state than either system individually. The 3DM-GX4-45 has a full-state dynamics model. The state propagation utilizes Newton’s and Euler’s equations of motion with the acceleration and angular rate treated as control inputs.

  • Page 45: Estimation Filter Convergence

    5.11.3 Output Uncertainty ™ The 3DM-GX4-45 estimation data set includes a filter status field that contains a set of status flags. These flags pertain to high covariance values for position, velocity, and attitude. These flags should be monitored and cross-check against the corresponding uncertainty fields when they appear.

  • Page 46: Vibration Isolation

    5.13 IMU Sensor Calibration ™ All of the sensor internal to the 3DM-GX4-45 are calibrated when it is manufactured. With the exception of the magnetometer field calibration (see Magnetometer Calibration on page recalibration should not be required unless the device has been under conditions that have exceeded the operating specifications.

  • Page 47: Sensor Installation

    ™ ™ 3DM-GX4 Inertial Navigation System Sensor Installation User Manual Sensor Installation 6.1 Sensor Mounting ™ The 3DM- GX4- 45 sensor housing is rated for indoor use only, unless used inside of a protective enclosure.  When using the internal GPS receiver, the GPS antenna connector on the side of the sensor must be accessible.

  • Page 48: Gps Antenna Installation

    The GPS antenna cable is plugged into the non-magnetic SMA-to- MMCX adapter cable ™ ™ supplied with the 3DM-GX4-45 . The adapter cable is then plugged into the 3DM-GX4-45 housing (see Interface and Indicators on page 9). The GPS antenna provided with the starter...

  • Page 49: Oem System Integration

    ™ control systems that react to the sensor outputs. For these applications the 3DM-GX4-45 available as a stand-alone component with optional interface connectors. The communication protocol used for configuring and acquiring sensor data and estimations outputs is available for these applications as well.

  • Page 50: Packet Builder

    7.1.1 Packet Builder To expedite program development, a packet builder tool is included in the MIP Monitor ™ software. The packet builder allows users to send multiple packets to the 3DM-GX4-45 and view the resulting reply data. ™ Applicable protocol structure and design is described 3DM-GX4-45 MIP DCP Manual.

  • Page 51: Sensor Direct Mode

    The sensor direct mode allows programmatic access of the internal IMU which has its own processor and protocol commands. For more ® information about using this mode, contact LORD MicroStrain Technical Support (see Technical Support on page 63).

  • Page 52: Gps Direct Mode

    The MIP Monitor software can be used to put the sensor in a mode in which direct access to ™ the internal GPS receiver is available. In this mode the 3DM-GX4-45 normal functionality is not available, and protocol commands cannot be used. This mode is called GPS Direct...

  • Page 53: Sensor Wiring

    ® Sensor power and serial communications cables are available from LORD MicroStrain come with the sensor starter kits. These cables will have the micro-DB9 connector on one end (to connect to the sensor) and either a standard DB9 on the other end (for RS232 communication) or a USB connector (for USB communications).

  • Page 54: Alternate Gps Equipment

    7.3 Alternate GPS Equipment ™ Other (external) GPS receivers, antennas and/or cables can be used with the 3DM-GX4-45 When using third party antennas the antenna cable length, antenna gain, and antenna power must be considered. For antennas with internal LNA (Low Noise Amplifiers) the power requirements should not have a minimum voltage below 3 volts and the current draw should not be over 20mA.
  • Page 55 ™ ™ 3DM-GX4 Inertial Navigation System OEM System Integration User Manual Figure 37 - GPS Source Select Figure 38 - External GPS Data...

  • Page 56: Sampling On Start-Up

    This technique will not work in MIP Monitor because it automatically puts the sensor in idle mode in order to allow device configuration. ® For more information refer to the "Startup Settings" Technical Note on the LORD MicroStrain ® website, or contact LORD MicroStrain...

  • Page 57: Troubleshooting

    ™ ™ 3DM-GX4 Inertial Navigation System Troubleshooting User Manual Troubleshooting 8.1 Troubleshooting Guide...
  • Page 58 (See Technical Support on page 63). 1.5 sensor is damaged If all power settings and connections have been verified, and ® the sensor is still unresponsive, contact LORD MicroStrain Technical Support (See Technical Support on page 63). 2.1 sensor not found in MIP Monitor 2.
  • Page 59 GPS source setting is set for an internal or external device as applicable. When using an external receiver, a receiver to ® serial translation program that utilizes the LORD MicroStrain MIP Data Communications Protocol is required to provide the GPS data to the sensor.
  • Page 60 When data recording is started the user can choose between CSV and Binary output formats. If the data is recorded in Binary format it will require a translation program that utilizes ® the LORD MicroStrain MIP Data Communications Protocol to make it human readable. 3.6 sensor has been magnetized...
  • Page 61 ™ ™ 3DM-GX4 Inertial Navigation System Troubleshooting User Manual Problem Possible cause and recommended solution offset or drift on the IMU sensor outputs. Sensor damage can occur as a result of excessive g-force other conditions outside of its operating specifications.

  • Page 62: Repair And Calibration

    LORD MicroStrain within the warranty period. ® This warranty does not extend to any LORD MicroStrain products which have been subject to misuse, alteration, neglect, accident, incorrect wiring, mis- programming, or use in violation of operating instructions furnished by LORD ®...

  • Page 63: Technical Support

    Troubleshooting User Manual 8.3 Technical Support ® There are many resources for product support found on the LORD MicroStrain website including technical notes, FAQs, and product manuals. http://www.microstrain.com/support_overview.aspx For further assistance our technical support engineers are available to help with technical and applications questions.

  • Page 64: Maintenance

    ™ ™ 3DM-GX4 Inertial Navigation System Maintenance User Manual Maintenance ™ There are no user-serviceable parts on the 3DM-GX4-45 . Removing the device cover or disassembling in any way will void the product warranty.

  • Page 65: Parts And Configurations

    For the most current product information, custom, and OEM options not listed below, refer to ® ® the LORD MicroStrain website or contact the LORD MicroStrain Sales Department. Table 7 - Model Numbers describes the standard models available at the time this manual was published.
  • Page 66 3DM-GX4-15 Starter Kit (USB, +/-5g, 300°/sec) 6233-4241 3DM-GX4-25 Starter Kit (RS232, +/-5g, 300°/sec) 6234-4221 3DM-GX4-25 Starter Kit (USB, +/-5g, 300°/sec) 6234-4241 3DM-GX4-45 Starter Kit (RS232, +/-5g, 300°/sec) 6236-4221 3DM-GX4-45 Starter Kit (USB, +/-5g, 300°/sec) 6236-4241 Table 8 - Example Part Numbers...

  • Page 67: Accessories

    The following parts are available for use with the 3DM-GX4 and some are included in sensor ® starter kits. For the most current product information refer to the LORD MicroStrain website or contact the Sales Department. See Sales Support on page ®...

  • Page 68: Warranty Information

    ® use in violation of operating instructions furnished by LORD MicroStrain . It also does not extend to any units altered or repaired for warranty defect by ®...

  • Page 69: Sales Support

    30 days from the date of receipt for a full refund (excluding shipping and handling), as long as the product is unaltered and ® undamaged. Items can only be returned after LORD MicroStrain has issued an Return Material Authorization (RMA). Items must be packed to withstand ®...

  • Page 70: Safety Information

    This section provides a summary of general safety precautions that must be understood and ® applied during operation and maintenance of components in the LORD MicroStrain Inertial Sensor Products.  Throughout the manual, ANSI Z535 standard safety symbols are used to indicate a process or component that requires cautionary measures.

  • Page 71: References

    References 12.1 Reference Documents ® Many references are available on the LORD MicroStrain website including product user manuals, technical notes, and quick start guides.  These documents are continuously updated and may provide more accurate information than printed or file copies. ...

  • Page 72: Glossary

    ™ ™ 3DM-GX4 Inertial Navigation System References User Manual 12.2 Glossary A/D Value The digital representation of analog voltages in an analog-to-digital (A/D) conversion. The accuracy of the conversion is dependent on the resolution of the system electronics. Higher res- olution produces a more accurate conversion.
  • Page 73 ™ ™ 3DM-GX4 Inertial Navigation System References User Manual ASTM (Association of Standards and Testing) A nationally accepted organization for testing and calibration of technological devices Attitude The orientaion of an object in space with reference to a defined frame, such as the North, East, Down (NED) frame Azimuth A horizontal arc measured between a fixed point (such as true north) and the vertical circle...
  • Page 74 ™ ™ 3DM-GX4 Inertial Navigation System References User Manual Delta-Theta The time integral of angular rate expressed with refernce to the device local coordinate system, in units of radians. Delta-velocity The time integral of velocity expressed with refernce to the device local coordinate system, in units of g*second where g is the standard gravitational constant.
  • Page 75 ™ ™ 3DM-GX4 Inertial Navigation System References User Manual Inertial Measurement System Inclinometer Device used to measure tilt, or tilt and roll. Inertial Pertaining to systems that have inertia or are used to measure changes in inertia as in angular or linear accelerations.
  • Page 76 ™ ™ 3DM-GX4 Inertial Navigation System References User Manual North, East, Down. A geographic reference system Original Equipment Manufacturer Offset A non-zero output signal of a sensor when no load is applied to it typically due to sensor imper- fections. Also called bias. Orientation The orientaion of an object in space with reference to a defined frame.
  • Page 77 ™ ™ 3DM-GX4 Inertial Navigation System References User Manual system has 65536 bits. Root Mean Squared Roll In navigation roll is what occurs when a horizontal force is applied at a distance right or left from the center of gravity of the platform, causing it to move side to side with respect to the sensor or platform frame origin.
  • Page 78 ™ ™ 3DM-GX4 Inertial Navigation System References User Manual UTC (Coordinated Universal Time) The primary time standard for world clocks and time. It is similar to Greenwich Mean Time (GMT). Vector A measurement with direction and magnitude with refernce from one point in space to another Velocity The rate of change of position with respect to time.

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