LORD 3DM-CX5-25 User Manual
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LORD 3DM-CX5-25 User Manual

Attitude and heading reference system
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LORD User Manual
3DM
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-CX5-25
Attitude and Heading Reference System (AHRS)

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Summary of Contents for LORD 3DM-CX5-25

  • Page 1 LORD User Manual ® -CX5-25 Attitude and Heading Reference System (AHRS)
  • Page 2 ® MicroStrain Sensing Systems 459 Hurricane Lane Suite 102 Williston, VT 05495 United States of America Phone: 802-862-6629 www.microstrain.com sensing_support@LORD.com sensing_sales@LORD.com Copyright © 2018 LORD Corporation ® ® ® ® ™ ® ® ® ® ® , 3DM-DH , 3DM-DH3...

  • Page 3: Table Of Contents

    ® -CX5-25 User Manual Table of Contents System Family Overview Sensor Overview Components Basic Setup and Operations Software Installation System Connections Software Interface 3.3.1 Interactive Help Menu Sensor Communication Sensor Settings 3.5.1 Saving Configurations Data Monitoring and Recording View Recorded Data Interface and Indicators Sensor Measurements Direct Sensor Measurements (IMU Outputs)
  • Page 4 ® -CX5-25 User Manual Magnetometer Auto Calibration 5.3.1 Enable 5.3.2 Capture Magnetometer Manual Calibration Estimation Filter Aiding Heading Aiding Settings 5.6.1 Bias Convergence Adaptive Anomaly Rejection 5.7.1 Gravity Adaptive 5.7.2 Mag Adaptive Communications Bandwidth Platform Frame Transformation 5.10 Estimation Filter Operation 5.11 Estimation Filter Convergence 5.11.1 Initial Convergence...
  • Page 5 ® -CX5-25 User Manual Sampling on Start-up Connecting to a Datalogger Using Wireless Adapters Troubleshooting Troubleshooting Guide Repair and Calibration Maintenance Technical Support Parts and Configurations 10.1 Standard Configurations 10.2 Accessories 10.3 Sales Support Specifications 12.1 3DM-CX5 Development Kit Reference Documents Glossary...

  • Page 6: System Family Overview

    The LORD Sensing MIP Data Communications Protocol (DCP) that is used to communicate with LORD Sensing 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.

  • Page 7: Sensor Overview

    Auto-Adaptive Extended Kalman Filter (EKF) allows the 3DM-CX5-25 to perform well in a wide variety of applications that require low noise, drift, gain, and offset errors. scale factor estimation, and bias estimation outputs are available.

  • Page 8: Components

    User Manual Components The 3DM-CX5-25 Inertial Sensor can be purchased by itself or as part of a Development Kit. All software, drivers, and links to detailed documentation are included with the sensor purchase. For a complete list of available configurations, accessories, additional system products, and ordering...

  • Page 9: Basic Setup And Operations

    User Manual Basic Setup and Operations To acquire sensor measurements and computed outputs, the 3DM-CX5-25 uses a host computer, an RS232 or USB communications port, and applicable software. The LORD Sensing MIP Monitor software is provided with the system and includes all functions needed for sensor configuration and data acquisition.

  • Page 10: Software Installation

    User Manual Software Installation NOTE The MIP Monitor Software Suite includes hardware drivers required for 3DM-CX5-25 sensor operation. Sensors will not be recognized without these drivers installed. To Install the MIP Monitor software on the host computer, complete the following steps: 1.

  • Page 11: System Connections

    Specifications on page 61 and active ( To acquire sensor data the following components are needed: 3DM-CX5-25 sensor, communication cable, power cable (as applicable for RS232 communications), connectivity board, and a host computer with LORD Sensing MIP Monitor installed.

  • Page 12: Software Interface

    ® -CX5-25 User Manual Software Interface The MIP Monitor software includes a main window with system information and menus, a device settings window, and several data monitoring windows. The main window provides an overview of connected devices. Devices are selected by clicking on them.

  • Page 13: Sensor Communication

    ® -CX5-25 User Manual Sensor Communication Once power has been applied to the sensor, it is functional. 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 14: Sensor Settings

    Device Settings, or select Settings > Device from the main menu. a. Main menu tabs: The main tabs divide the settings into functional groups for the available measurements. For the 3DM-CX5-25 these include calculated measurements (Estimation Filter) and direct inertial sensor measurements (IMU/AHRS).

  • Page 15: Saving Configurations

    ® -CX5-25 User Manual 3.5.1 Saving Configurations Sensor settings are saved temporarily by selecting the OK button in the Device Setup window after configuration, but they are lost when the device is powered off. To save current settings, so they are automatically restored the next time the device is powered on, select Settings >...

  • Page 16: Data Monitoring And Recording

    Each view corresponds to one of the main categories in the Device Settings window. For example, the 3DM-CX5-25 includes Sensor Data Monitoring for the IMU/AHRS measurements and EF Monitoring for the Estimation Filter output. During viewing and recording, only...
  • Page 17 ® -CX5-25 User Manual Figure 11 - Data Streaming is an example of Sensor Data Monitoring, which displays the selected IMU/AHRS measurements. In data monitoring windows, no data will be displayed until data streaming is started, and no data will be recorded (even if it is being viewed) until data recording is initiated (armed).

  • Page 18: View Recorded Data

    CSV files can be viewed with Microsoft Excel, Quattro Pro, Open Office, or other CSV editors and spreadsheet programs. Data recorded in Binary format requires a translation program utilizing the LORD Sensing MIP Data Communications Protocol (DCP) to make it user-readable.
  • Page 19 ® -CX5-25 User Manual 4. To end recording press the Arm Recording button again, and select OK in the confirmation prompt window. 5. Select the Stop Streaming icon to end sampling. 6. Use the red "X" in the upper right of the sensor monitoring window to exit monitoring mode.

  • Page 20: Interface And Indicators

    ( The indicators on the 3DM-CX5-25 include a device status indicator and the device information label. The table below describes the basic status indicator behavior. includes the sensor frame diagram (axis...

  • Page 21: Sensor Measurements

    -CX5-25 User Manual Sensor Measurements The 3DM-CX5-25 block diagram describes its primary hardware components and internal configuration. Integrated Micro-Electro-Mechanical System (MEMS) sensors within the 3DM-CX5-25 are collectively known as the Inertial Measurement Unit (IMU) and include tri-axial gyroscopes (gyros), tri-axial accelerometers.

  • Page 22: Direct Sensor Measurements (Imu Outputs)

    ® -CX5-25 User Manual Direct Sensor Measurements (IMU Outputs) The sensors in an Inertial Navigation System (INS), from which measurements for navigation and orientation are obtained, are collectively known 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 23 User Manual Table 2 - IMU Measurements lists the IMU measurements available for the 3DM-CX5-25. Additional measurement units may be available in MIP Monitor for some outputs, however they are converted values and do not represent the actual sensor outputs. Only actual output units are listed.

  • Page 24: Computed Outputs (Estimation Filter)

    User Manual Computed Outputs (Estimation Filter) The computed outputs are measurements from the 3DM-CX5-25 IMU sensors that are blended through an Auto-Adaptive Extended Kalman Filter (EKF) algorithm. The Kalman Filter produces a better estimation of attitude and heading (AHRS) outputs than can be achieved by the inertial sensors Table 3 - Estimation Filter Outputs individually.
  • Page 25 ® -CX5-25 User Manual Units Description Measurement indicates the current state of the EF, Filter Status such as running or initializing GPS time corresponding to the GPS Time weeks & seconds calculated filter solution Euler angles representation of Attitude orientation expressed as roll, pitch and yaw (Euler RPY) radians (RPY) with one-sigma uncertainly...

  • Page 26: Sensor Reference Frames

    ® -CX5-25 User Manual Sensor Reference Frames 4.3.1 Geodetic Frame The World Geodetic System is the standard for cartography and navigation. The latest revision, WGS84, is the reference coordinate system for GPS. It also calculates the magnitude of the local gravity vector using the WGS84 reference formulas.

  • Page 27: North East Down (Ned) Frame

    ® -CX5-25 User Manual 4.3.2 North East Down (NED) Frame The North-East-Down (NED) frame is a local coordinate frame, which is formed by a tangent plane located at a particular point (current coordinates) on the WGS84 reference ellipse. The NED frame is constructed with the (true) North vector along the line of longitude, the East vector along the line Figure 18 - North East of latitude, and the Down vector normal to and towards the tangent plane (...

  • Page 28: Sensor Frame

    Device Settings > EF settings > Geographic. Refer to the 3DM-CX5-25 dimensional diagram for the location of the measurement origin ( Sensor Dimensions and Origin on page 1...

  • Page 29: Platform Frame

    4.3.4 Platform Frame The 3DM-CX5-25 includes the option to define an orientation transformation and offset distance from the sensor frame to a user-definable platform frame. 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 30 ® -CX5-25 User Manual Figure 21 -Platform Frame Settings The orientation transformation affects the following EF outputs: attitude, position, linear and compensated acceleration, compensated angular rate, and gravity vector. It also affects the following IMU outputs: acceleration, angular rate, magnetic field vector, delta Theta, and delta see Computed Outputs (Estimation Filter) on page 24 velocity ( Transformed acceleration is expressed at the location of the sensor but within the platform frame.

  • Page 31: Performance Optimization

    ® -CX5-25 User Manual Performance Optimization 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. Allow 2-3 minutes for the sensor to warm up and for the temperature to stabilize for the best bias capture.

  • Page 32: Tare Mounting Pitch-Roll

    This function captures the current pitch-roll orientation of the device and sets it as the level reference, providing a convenient way to set the sensor to vehicle frame transformation. For more information on the corresponding LORD Sensing MIP Data Communications Protocol (DCP) command, see the DCP Manual.

  • Page 33: Magnetometer Auto Calibration

    ® -CX5-25 User Manual Magnetometer Auto Calibration 5.3.1 Enable Enabling the EF Mag Hard Iron Auto Calibration allows estimation of the magnetometer bias (bias tracking) for purposes of auto-calibration. Enabling the EF Mag Soft Auto Calibration allows estimation of the magnetometer scale factor (scale factor tracking) for purposes of auto-calibration. To enable, select the sensor name in the MIP Monitor software main window, then select Settings >...

  • Page 34: Capture

    These maneuvers are necessary to establish the magnetometer offset and scale factors. For more information on the corresponding LORD Sensing MIP Data Communications Protocol (DCP) command, see the DCP Manual.

  • Page 35: Magnetometer Manual Calibration

    However, often these sources are hard to avoid or are hidden. To mitigate this effect when using the 3DM-CX5-25 magnetometer to aid in heading estimations, a field calibration of the magnetometer after final installation is highly recommended. This can be accomplished using LORD Sensing MIP Hard and Soft Iron Calibration software.
  • Page 36 ® -CX5-25 User Manual 3. The sensor should automatically appear in the sensor list. If not, use the Refresh button Figure 26 - Sensor Menu to query it and then select the sensor ( 4. Select the Arm Recording button next to Collect Data. The software will begin taking readings, as indicated by the points counter in the graphing window.
  • Page 37 ® -CX5-25 User Manual the best 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. 7.

  • Page 38: Estimation Filter Aiding

    ® -CX5-25 User Manual Estimation Filter Aiding There are two categories to customize heading and pitch-roll. To enter the Estimation Filter Aiding menu, select the sensor name in the MIP Monitor software main window, then select Settings > Device > Estimation Filter > EF Aiding. 1.

  • Page 39: Heading Aiding Settings

    Heading Aiding Settings Device settings are stored in the sensor memory. Only the configuration options that are available for the type of sensor being used are displayed in the configurations menus. The 3DM-CX5-25 has two heading options. If the setting is none, the estimated heading will drift when little-or-no changes in velocity are sensed (e.g.

  • Page 40: Bias Convergence

    ® -CX5-25 User Manual 5.6.1 Bias Convergence Accurate estimation of the biases can take several minutes to converge, therefore after the filter is initialized, the free-inertial performance will continue to improve until the bias estimations settles. The MEMS sensor manufacturers quote bias drift stability numbers which correspond to the expected drift in bias while the sensor is operating.

  • Page 41: Mag Adaptive

    ® -CX5-25 User Manual 5.7.2 Mag Adaptive Enabling this feature will allow the filter to reject magnetometer readings when the magnitude error exceeds the high limit (in m/s ^ 2). The bandwidth (in Hz) sets the cutoff frequency of the low pass see Communications Bandwidth on page 42 filter applied to the magnetometer error ( ).

  • Page 42: Communications Bandwidth

    5.10 Estimation Filter Operation The 3DM-CX5-25 combines the information from the IMU sensors to calculate an Attitude and Heading Reference System (AHRS) solution that incorporates the strengths of the individual sensors while minimizing their weaknesses.

  • Page 43: Estimation Filter Convergence

    5.11.2 Output Uncertainty The 3DM-CX5-25 estimation data set includes a filter status field that contains a set of status flags. These flags pertain to high covariance values for attitude and inertial sensor parameters. These flags should be monitored and cross-checked against the corresponding uncertainty fields when they appear.

  • Page 44: Vibration Isolation

    5.13 IMU Sensor Calibration All of the internal sensors in the 3DM-CX5-25 are calibrated when the device is manufactured, and the calibration values are saved in the device memory. With the exception of the magnetometer field calibration (...

  • Page 45: 6.1 Import And Export Settings

    The import and export settings features provide a consolidated file of the user settings, enabling Device Settings information to be saved and shared. For example, exporting settings to the LORD technical support team helps facilitate fast and accurate resolution of technical issues.

  • Page 46: Sensor Installation

    ® -CX5-25 User Manual Sensor Installation Sensor Mounting See the CX5 Interface Control Document for detailed drawings and mounting instructions. The sensor has three holes for fastening to ensure maximum stability. Mounting fasteners should be 2- 56 x ½" button head screws, either brass or 300 series stainless steel. The sensor can be mounted in any orientation, as required for the application.

  • Page 47: System Integration

    The C-Series Connectivity Board may be used as a standalone interface or may be used as a reference design for embedding the 3DM-CX5-25 in the user's application. For detailed C-Series connectivity board reference design documentation, see...

  • Page 48: Packet Builder

    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-CX5-25 and view the resulting reply data. Applicable protocol structure and design is described in the 3DM-CX5-25 LORD Sensing MIP Data Communications Protocol (DCP) Manual.

  • Page 49: Sensor Direct Mode

    When in Sensor Direct mode the device normal functionality is not available. The protocol commands used to interface with the IMU are a subset of the standard LORD Sensing MIP Data Communications Protocol (DCP) and are further described in the LORD Sensing MIP Data Communications Protocol (DCP) manual.

  • Page 50: Sensor Wiring

    Logic Level GPIO Logic Level Disable Disable (Open or Low = Enable) Mounting Holes Chassis Chassis Ground * USB is not available on the 3DM-CX5-25 and may be left connected to USB or unconnected. Figure 36 -Pin Locations and Functions...

  • Page 51: Sampling On Start-Up

    MIP Monitor for data logging is not required. This functionality can also be embedded in user- designed applications by using the corresponding LORD Sensing MIP Data Communications Protocol (DCP) command. To view or download the DCP Manual, go to: http://www.microstrain.com/support/documentation, from the drop-down menu select 3DM-CX5-...

  • Page 52: Connecting To A Datalogger

    Many inertial applications incorporate dataloggers of all different types to collect and distribute sensor outputs. For more information and examples refer to the "Using Dataloggers with Inertial Sensors" Technical Note on the LORD Sensing website, or contact LORD Sensing Technical Support ( Technical Support on page 57...

  • Page 53: Troubleshooting

    ® -CX5-25 User Manual Troubleshooting Troubleshooting Guide...
  • Page 54 NOTE: if the baud rate is set higher than the computer serial port is capable of reading, communication will be permanently lost with the device. To recover, it will need to be connected to a higher speed port, connected via USB cable, or sent to LORD...
  • Page 55 If no conclusion can be determined, or to send a device in for repair, contact LORD See Technical Support on page Sensing Technical Support ( 3.1 sampling settings are incorrect...

  • Page 56: Repair And Calibration

    LORD Sensing model number and serial number, as well as your name, organization, shipping address, telephone number, and email. Normal turn- around for RMA items is seven days from receipt of item by LORD Sensing. Warranty Repairs LORD Sensing warrants its products to be free from defective material and workmanship for a period of one (1) year from the original date of purchase.

  • Page 57: Maintenance

    -CX5-25 User Manual Maintenance There are no user- serviceable parts on the 3DM-CX5-25. Removing the device cover or disassembling in any way voids the product warranty. Technical Support There are many resources for product support found on the LORD Sensing website including technical notes, FAQs, and product manuals.

  • Page 58: Parts And Configurations

    Parts and Configurations 10.1 Standard Configurations For the most current product information, custom, and OEM options not listed below, refer to the LORD Sensing website or contact the LORD Sensing Sales Department. Table 4 - Model Numbers describes the standard models available at the time this manual was published.
  • Page 59 ® -CX5-25 User Manual The same options are available in each model, and are indicated in the last four digits of the product see Components on page 1 part number. For a list of the starter kit contents, ( Figure 38 -Standard Part Numbers...

  • Page 60: Accessories

    -CX5-25 User Manual 10.2 Accessories The following parts are available for use with the 3DM-CX5-25. For the most current product see Sales Support information refer to the LORD Sensing website or contact the Sales Department. ( on page 60 Description...

  • Page 61: Specifications

    ® -CX5-25 User Manual Specifications General Integrated Triaxial accelerometer, triaxial gyroscope, triaxial sensors magnetometer, and temperature sensors, Inertial Measurement Unit (IMU) outputs: acceleration, angular rate, magnetic field, ambient pressure, Delta-theta, Delta-velocity Computed outputs Extended Kalman Filter (EKF): filter status, timestamp, attitude estimates (in Euler angles, quaternion, orientation Data outputs matrix), linear and compensated acceleration, bias...
  • Page 62 ® -CX5-25 User Manual Computed Outputs EKF outputs: ±0.25° RMS roll and pitch, ±0.8° RMS heading (typ) Attitude accuracy CF outputs: ±0.5° RMS roll and pitch, ±1.5° RMS heading (typ) Attitude heading range 360° about all axes Attitude resolution < 0.01° Attitude repeatability 0.2°...

  • Page 63: 12.1 3Dm-Cx5 Development Kit

    ® -CX5-25 User Manual 12.1 3DM-CX5 Development Kit See the 3DM- CX5 Reference Design Documentation for detailed drawings and notes on the components included in the development kit. Figure 39 -C-Series Connectivity Board...

  • Page 64: Reference Documents

    -CX5-25 User Manual Reference Documents Many references are available on the LORD Sensing 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 65: Glossary

    ® -CX5-25 User Manual 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 resolution produces a more accurate conversion. Acceleration In physics, acceleration is the change in the rate of speed (velocity) of an object over time.
  • Page 66 ® -CX5-25 User Manual ASTM (Association of Standards and Testing) a nationally accepted organization for the testing and calibration of technological devices Attitude the orientation 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 passing...
  • Page 67 ® -CX5-25 User Manual Delta-Theta the time integral of angular rate expressed with reference to the device local coordinate system, in units of radians Delta-velocity the time integral of velocity expressed with reference to the device local coordinate system, in units of g*second where g is the standard gravitational constant ECEF (Earth Centered Earth Fixed) a reference frame that is fixed to the earth at the center of the earth and turning about earth's axis in the...
  • Page 68 ® -CX5-25 User Manual Host (computer) The host computer is the computer that orchestrates command and control of attached devices or networks. 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 INS (Inertial Navigation System) systems that use inertial measurements exclusively to determine position, velocity, and attitude, given...
  • Page 69 ® -CX5-25 User Manual NED (North-East-Down) A geographic reference system acronym for Original Equipment Manufacturer Offset A non-zero output signal of a sensor when no load is applied to it, typically due to sensor imperfections. Also called bias. Orientation The orientation of an object in space with reference to a defined frame. Also called attitude. Pitch In navigation pitch is what occurs when vertical force is applied at a distance forward or aft from the center of gravity of the platform, causing it to move up or down with respect to the sensor or platform...
  • Page 70 ® -CX5-25 User Manual acronym for 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 71 ® -CX5-25 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 reference from one point in space to another Velocity The rate of change of position with respect to time.

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