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Lord MicroStrain 3DM-GX4-45 User Manual Download Page 25

3DM-GX4

™

-45

™

Inertial Navigation System

User Manual

Sensor Measurements

25

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. External aiding systems,

such as Wide Area Augmentation System (WAAS) in the US, help compensate for certain

error sources that can affect GPS accuracy. Position of the antenna is also an important

consideration (

see GPS Antenna Installation on page 48

)

Readings and information are available directly from the GPS receiver.

Table 5 - GPS Outputs

describes the available outputs. GPS reporting and recording can be enabled in the

MIP Monitor software through the Settings > Device > GPS (tab) (

Figure 17 - GPS Settings

).

To view and record GPS outputs,

see Basic Setup and Operations on page 10

.

Figure 17 -

GPS Settings

Summary of Contents for 3DM-GX4-45

Page 1: ...LORD USER MANUAL 3DM GX4 45 Miniature GPS Aided Inertial Navigation System GPS INS ...

Page 2: ...s LORD com Copyright 2014 LORD Corporation IEPE Link Torque Link 3DM RQ1 Strain Wizard DEMOD DC DVRT DVRT Link WSDA HS Link TC Link G Link V Link SG Link ENV Link Watt Link Shock Link LXRS Node Commander SensorCloud Live Connect MathEngine EH Link 3DM FAS A 3DM GX1 3DM GX3 3DM GX4 3DM DH 3DM DH3 EmbedSense MicroStrain and Little Sensors Big Ideas are trademarks of LORD Corporation Document 8500 00...

Page 3: ...Interactive Help Menu 13 3 4 Sensor Communication 14 3 5 GPS Link 15 3 6 Sensor Settings 15 3 6 1 Saving Configurations 17 3 7 Data Monitoring and Recording 18 3 8 Viewing Data 21 4 Sensor Measurements 22 4 1 Direct Sensor Measurements IMU Outputs 23 4 2 Global Positioning System GPS Outputs 25 4 3 Computed Outputs Estimation Filter PVA 27 4 4 Sensor Reference Frames 30 4 4 1 Geodetic Frame 30 4 4...

Page 4: ...set 41 5 9 Vehicle Dynamics Mode 42 5 10 Estimation Filter Operation 43 5 11 Estimation Filter Convergence 45 5 11 1 Initial Convergence 45 5 11 2 Bias Convergence 45 5 11 3 Output Uncertainty 45 5 12 Vibration Isolation 46 5 13 IMU Sensor Calibration 46 5 14 Temperature Compensation 46 6 Sensor Installation 47 6 1 Sensor Mounting 47 6 2 GPS Antenna Installation 48 7 OEM System Integration 49 7 1 ...

Page 5: ...talogger 56 7 6 Using Wireless Adapters 56 8 Troubleshooting 57 8 1 Troubleshooting Guide 57 8 2 Repair and Calibration 62 8 3 Technical Support 63 9 Maintenance 64 10 Parts and Configurations 65 10 1 Standard Configurations 65 10 2 Accessories 67 10 3 Warranty Information 68 10 4 Sales Support 69 11 Safety Information 70 12 References 71 12 1 Reference Documents 71 12 2 Glossary 72 ...

Page 6: ...sated 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 Each device comes with the LORD MicroStrain MIP Monitor software that can be used for device configuration real time measurement monitori...

Page 7: ...mathematically aligned to an orthogonal coordinate system The combination of sensors environmental compensation and dual on board processing with an Extended Kalman Filter EKF allow the 3DM GX4 45 to perform well in a wide variety of applications that require ultra low noise drift gain and offset errors Settings for sensor filtering sensor noise sensor bias bias estimation scale factor estimation ...

Page 8: ...a adapter cable 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 65 Item Description Quantity A 3DM GX4 45 Inertial Sensor 1 B Communications cable USB or RS232 1 C Power supply and country plug adap...

Page 9: ... 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 32 Figure 2 Interface and Indicators Indicator Behavior Device Status device status indicator OFF no power appl...

Page 10: ...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 s...

Page 11: ... or by running the Autorun exe file from the software directory in Windows Explorer 2 In the software installation menu select Install MIP Monitor Software and follow the on screen prompts to completion 3 If the sensor has internal magnetometers select Install MIP Hard and Soft Iron Calibration Software and follow the on screen prompts to completion This is used for magnetometer field calibration ...

Page 12: ...nly power supplies within the operating range of the sensor or damage or injury could result Once power is applied the sensor is on and active 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 a...

Page 13: ...he header row menus Figure 6 Main Window The header row menu includes selections for data sampling recording device settings opening windows selecting which open window to view and advanced features such as selecting the communications mode The icon toolbar includes buttons for help menu access device refresh and data sampling and recording see Data Monitoring and Recording on page 18 Figure 6 Mai...

Page 14: ...to establish sensor communication 2 Open the MIP Monitor software 3 The sensor should appear in the device list automatically when the software is opened and includes the device information and communication port assignment Figure 8 Sensor Communication If it is not automatically discovered use the refresh button to search for the sensor Figure 8 Sensor Communication NOTE If data is not actively b...

Page 15: ...IP Monitor software will display the satellite and link statistics see Global Positioning System GPS Outputs on page 25 Communication with the satellites is required for proper sensor operation although some measurement outputs will be available without them 3 6 Sensor Settings Device settings are stored in the sensor memory Only the configuration options that are available for the type of sensor ...

Page 16: ...dditional sub menu tabs including the Message Format tab The Message Format tabs allows the user to select the measurement type to be displayed and recorded b1 and the data rate rate at which data is sent to the host computer in samples second b2 c Measurement parameters other sub menu tabs Available sub menu tabs besides the Message Format tab depend on the selected main menu tab These tabs inclu...

Page 17: ...elect Settings Save Current Settings from the main window Figure 10 Save Sensor Settings If the settings are not saved in this manner they will be lost when the sensor is powered off If the sensor settings are saved as described the setting will remain intact when the sensor is powered on again Previously saved settings can be recalled by selecting the sensor in the device list and the selecting S...

Page 18: ...MIP Monitor menus the same icons are used to control data streaming sampling and recording shown in Table 3 Sampling and Recording Controls These icons can be found in the MIP Monitor main window icon toolbar and in each data monitoring window The same commands are also found in the main window Control menu Figure 11 Main Window Controls Icon Command Run start data streaming Stop end data streamin...

Page 19: ...corded however it is not necessary to be viewing it in a data monitoring window Data monitoring is used primarily to confirm the system is operating correctly or to view the outputs in near real time If sensor setup has already been confirmed streaming and recording can be initiated from the main window Figure 12 Data Monitoring and Streaming is an example of Sensor Data Monitoring which displays ...

Page 20: ...ditors such as 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 To end recording press the Arm Recording button again and select OK to the confirmation prompt 6 Select the Stop Streaming icon to end sampling 7 Use the red X in the u...

Page 21: ...irectory on the host computer desktop CSV files can be viewed with Microsoft Excel Quattro Pro Open Office or other CSV editors and spreadsheet programs Data recorded in Binary format will require a translation program that utilizes the LORD MicroStrain MIP Data Communications Protocol to make it user readable Figure 14 Exploring Data NOTE Data in the data files are displayed in time sequence If m...

Page 22: ...d delta v change in velocity Temperature and pressure sensors provide environmental information for measurement compensation and altitude estimations GPS information can be read directly and is also used in the computed navigation estimations Computed estimations for position velocity and attitude PVA and attitude and heading reference systems AHRS are available outputs on the 3DM GX4 45 To achiev...

Page 23: ...he IMU sensors can be read directly to report stand alone inertial measurements Because the sensor system is digital the analog voltage readings from the sensors are converted into a digital equivalent value based on the volt to bit scale of the internal analog to digital voltage converter A D converter For example a 16 bit system will have 65536 A D values bits applied over the output voltage ran...

Page 24: ...l force g three axis acceleration readings in engineering units Magnetometer Gauss G three axis magnetic field readings in engineering units Angular Rate degrees second radian second three axis rotational velocity reading from gyroscope in engineering units Delta Angle theta degrees radians time integral of angular rate with configurable time period Delta Velocity g seconds time integral of accele...

Page 25: ...ropriate confidence level External aiding systems such as Wide Area Augmentation System WAAS in the US help compensate for certain error sources that can affect GPS accuracy Position of the antenna is also an important consideration see GPS Antenna Installation on page 48 Readings and information are available directly from the GPS receiver Table 5 GPS Outputs describes the available outputs GPS r...

Page 26: ...ers accuracy speed along direction of travel in 2D and 3D space as reported by GPS module only DOP Data Dilution of Precision DOP ratings for accuracy of GPS readings UTC Data time and date Coordinated Universal Time UTC to fractional seconds with leap year seconds adjustment and confidence indicator Also week number month date and year Clock Information seconds clock accuracy metrics GPS Fix Info...

Page 27: ... magnetometer readings Position is the coordinate location of the sensor and velocity is the rate of change from that position Attitude is an estimation of the sensor s orientation in space and is generated from the sensed acceleration and magnetic field vectors and gyroscope outputs Attitude is reported as roll pitch and yaw All output estimates represent the orientation of the device relative to...

Page 28: ...d sensor inputs and EF with reference to North East Down coordinate system and with uncertainty estimation available Attitude Euler RPY radians Euler angles representation of orientation expressed as roll pitch and yaw RPY with one sigma uncertainly estimation available Attitude Matrix radians Transformation matrix that describes orientation with reference to the Earth Centered Earth Fixed ECEF co...

Page 29: ...radians heading value relative to True North with one sigma uncertainly estimation WMM Magnetic Model Solution Gauss World Magnetic Model WMM Local Intensity estimate from magnetometers and GPS Pressure Altitude meters altitude pressure milli bars temperature C density kg m3 altitude estimate based on barometric pressure air temperature and density with available correction based on the U S Standa...

Page 30: ...ordinates are latitude φ longitude λ and height h above the reference ellipsoid Latitude ranges from 90 degrees at the South Pole to 90 degrees at the North Pole Longitude ranges from 180 to 180 degrees with 0 degrees being the prime meridian The 180 180 degree switchover occurs in the middle of the Pacific Ocean and includes a section of the International Date Line The model takes into account th...

Page 31: ... line of longitude the East vector along the line of latitude and the Down vector normal to and towards the tangent plane Figure 20 North East Down Frame The assumption when using the NED frame is that the local surface can be reasonably approximated by a flat plane For most applications this assumption is valid and provides a more intuitive reference frame for expressing velocity and attitude inf...

Page 32: ... that when the connector on the device is pointed true north and the device is upright and level the sensor frame will match the NED frame exactly giving zero rotation The 3DM GX4 45 reports acceleration angular rate delta Theta delta velocity and sensor biases in this frame The sensor frame can be viewed in the MIP Monitor software through the View 3D Attitude menu This window displays the orient...

Page 33: ...h respect to the origin of the sensor frame expressed in the sensor frame In the following example Figure 22 Platform Frame Transformation the user has defined the desired reference point on the platform frame to be located at the front bumper of the vehicle In accordance with aircraft co ordinate systems the vehicle frame is oriented with the x axis pointed in the forward direction of travel the ...

Page 34: ...n Linear Angular Rate and Gravity Vector The offset affects the following EF output Position LLH IMU sensor outputs see Direct Sensor Measurements IMU Outputs on page 23 are always expressed in the sensor frame and are unaffected by the platform frame transformation or offset Additionally the transformed acceleration is expressed at the location of the sensor but within the platform frame For exam...

Page 35: ...al installation is highly recommended This can be accomplished using LORD MicroStrain MIP Hard and Soft Iron Calibration software This software is included with the MIP Monitor Software Suite see Software Installation on page 11 The following are instructions for field calibrating the magnetometers 1 Connect and power on the sensor as normal 2 Open the MIP Hard and Soft Iron Calibration software 3...

Page 36: ...e Spherical Fit or Ellipsoid Fit button depending on the application Spherical Fit is often the best fit for applications with calibration rotations restricted to a 2D plane For example a ground vehicle or a boat because it will not likely not be rotated on all three axis Ellipsoid Fit is generally a better correction when soft iron effects are present but only if enough data points can be collect...

Page 37: ...est the calibration by first selecting Clear Plot to clearing the graph and then select Plot Data to refresh the data points that we just collected If they do not appear click Load Data and reload them for the saved file 9 Click Corrected Fit A Spherical Fit of the data will be plotted This represents how the calibration predicts the magnetometer data should look during actual operation 10 Click P...

Page 38: ...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 Select Settings Capture Gyro Bias Figure 27 Gyro Bias Capture The sensor must remain stationary for about twenty seconds while the outputs are being measured A status message will appear when the capture has been completed Figure 27 Gyro Bi...

Page 39: ...drift with the drift of the gyroscopes If the setting is the magnetometer there will be no drift but the accuracy will only be as good as the magnetometer If using GPS velocity as a heading reference the sensor or sensor platform has to be moving or there will be no heading reading Moving the platform in a dynamic way will assist in recapturing the heading for example slight s turns in an aircraft...

Page 40: ...nnection 5 6 Platform Frame Transformation The transformation from the sensor frame to the platform frame see Platform Frame on page 33 should be defined to the highest angular accuracy possible The easiest way to accomplish this is to co align the frames If this is not possible using a simple transformation such as 90 or 180 degree rotations on a single axis are preferred For complex transformati...

Page 41: ...tor allows entry of the offset in the Settings Device Estimation Filter Mounting Antenna Offset Figure 29 GPS Antenna Offset For the best possible position accuracy the GPS antenna offset should be defined to the highest degree possible preferably down to the centimeter or millimeter range Inaccuracies become non negligible at 2 to 3 centimeters The user should strive to minimize this distance as ...

Page 42: ...different dynamic platforms have on changes in GPS satellite pseudo ranges Each platform setting portable automotive and airborne have different velocity and altitude limitations 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 ...

Page 43: ...urces of error exist when making attitude estimates First the algorithm assumes the acceleration vector is dominated by Earth s gravity with only transient linear accelerations When long duration linear accelerations are experienced such as when an aircraft performs a sustained 2G turn the AHRS will report incorrect pitch and roll angles This error is the direct result of the assumption that the a...

Page 44: ...led a sensor fusion filter as it is combining similar information from multiple sources in a complementary way This combination takes into account the statistical properties of the sensors used providing a better estimate of the true 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 ...

Page 45: ... poor value is used for initialization and when the vibration environment is strong Should this occur it is recommended that the filter is reset and a new attitude estimate is provided Refer to the 3DM GX4 45 MIP DCP Manual for the various ways of providing an initial attitude estimate through a user designed interface 5 11 2 Bias Convergence Accurate estimation of the biases can take several minu...

Page 46: ...With the exception of the magnetometer field calibration see Magnetometer Calibration on page 35 recalibration should not be required unless the device has been under conditions that have exceeded the operating specifications For example if the sensor has been exposed to excessive shock beyond the rated g force performance may be compromised Indications of internal sensor damage may be seen as mea...

Page 47: ... connector on the side of the sensor must be accessible The sensor has two mounting tabs with holes for fastening There are two additional holes used for precise alignment with 2mm dowel pins One of the holes is slotted to allow for relaxed pin positioning accuracy The sensor can be mounted in any orientation as required for the application see Sensor Reference Frames on page 30 The axes are label...

Page 48: ...tenna must be mounted with an unobstructed line of sight to the sky in order to establish GPS satellite links This can be accomplished through a window or more optimally by placing the antenna outdoors Use the GPS Monitor in the MIP Monitor software to observe satellite link strength during installation to optimize placement see Global Positioning System GPS Outputs on page 25 For the most accurat...

Page 49: ...all commands available for controlling the acquiring data from the 3DM GX4 45 including many that are not available in the MIP Monitor software Programming is performed through a standard serial interface program The programming interface is comprised of a compact set of setup and control commands and a very flexible user configurable data output format The commands and data are divided into two c...

Page 50: ... and view the resulting reply data Applicable protocol structure and design is described 3DM GX4 45 MIP DCP Manual The manual can be found on the LORD MicroStrain website Support page or by contacting Technical Support see Technical Support on page 63 To use the packet builder select Advanced Packet Builder from the MIP Monitor main window Figure 33 Packet Builder The sensor must be in the Standar...

Page 51: ...ernal 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 To enter this mode select Advanced Communications Sensor Direct from the MIP Monitor main window Once in this mode the device status message will indicate Sensor Direct Mode Figure 34 Sensor Direct Mode To exit Sensor Dir...

Page 52: ...ion with the receiver through an external utility program available from the GPS receiver manufacturer such as u Blox or by contacting LORD MicroStrain Technical Support see Technical Support on page 63 Also refer to the Using u blox Software Technical Note for specific instructions on that receiver see Reference Documents on page 71 To start communicating with the GPS receiver in GPS Direct mode ...

Page 53: ...ensor and either a standard DB9 on the other end for RS232 communication or a USB connector for USB communications Alternately the micro DB9 can be purchased from LORD MicroStrain with flying leads or the connector by itself can be purchased from the manufacturer Ulti Mate Connector Inc See Parts and Configurations on page 65 for a list of available options The connector interface includes connect...

Page 54: ...ferent GPS antenna always use the non magnetic MMCX to SMA adapter supplied with the 3DM GX4 45 unless the magnetometer is not used in the end application 7 3 1 GPS External Receiver To use an external GPS receiver the internal one must be disabled and a serial link established between the receiver and the sensor through the host computer A program is then written using the LORD MicroStrain MIP Da...

Page 55: ...3DM GX4 45 Inertial Navigation System User Manual OEM System Integration 55 Figure 37 GPS Source Select Figure 38 External GPS Data ...

Page 56: ...Support see Technical Support on page 63 7 5 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 Notes on the LORD MicroStrain website or contact LORD MicroStrain Technical Support see Technical Support on page 63...

Page 57: ...3DM GX4 45 Inertial Navigation System User Manual Troubleshooting 57 8 Troubleshooting 8 1 Troubleshooting Guide ...

Page 58: ...ware updater fails it is possible that the device can get stuck in the firmware update mode and the sensor will be non responsive Contact LORD MicroStrain Technical Support 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 ...

Page 59: ...iver is not communicating The GPS antenna requires unobstructed line of sight to the sky in order to link with the GPS satellites Also verify the GPS antenna is plugged into the sensor and the cable is intact Verify the 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 MicroStra...

Page 60: ...rding Data If the sensor is not recording activate it in the software Verify specific measurements have been enable for sampling and recording NOTE Data in the data files are displayed in time sequence If measurements are set to different sample rates not all time intervals will include a reading from each output that is being recorded 3 5 sensor data recorded in binary format When data recording ...

Page 61: ...em User Manual Troubleshooting 61 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: ...t of item by LORD MicroStrain Warranty Repairs LORD MicroStrain warrants its products to be free from defective material and workmanship for a period of one 1 year from the original date of purchase LORD MicroStrain will repair or replace at its discretion a defective product if returned to LORD MicroStrain within the warranty period This warranty does not extend to any LORD MicroStrain products w...

Page 63: ... manuals http www microstrain com support_overview aspx For further assistance our technical support engineers are available to help with technical and applications questions Technical Support sensing_support LORD com Phone 802 862 6629 Toll Free 800 449 3878 Fax 802 863 4093 SKYPE microstrain orientation support Live Chat is available from the website during business hours 9 00 AM to 5 00 PM East...

Page 64: ...45 Inertial Navigation System User Manual Maintenance 64 9 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: ...n website or contact the LORD MicroStrain Sales Department Table 7 Model Numbers describes the standard models available at the time this manual was published Once a model is selected the part number is further defined by desired configuration and interface options The model determines the first four digits of the product part number while the options are indicated in the last four digits Figure 3...

Page 66: ...tents see Components on page 8 Figure 39 Standard Part Numbers Description LORD MicroStrain Part Number 3DM GX4 15 Starter Kit RS232 5g 300 sec 6233 4221 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 Ta...

Page 67: ...ORD MicroStrain Part Number RS232 communications cable 4005 0037 USB communications cable 9022 0019 RS232 power supply 9011 0009 RS232 power supply country plug adapter kit 9011 0022 Gilsson GPS patch antenna with 3m cable 9100 0100 Antenna cable adapter MMCX to SMA 9022 0032 MIP Monitor Software Suite flash drive 8200 0020 Sensor mating connector micro DB9 with flying leads 6224 0100 Table 9 Sens...

Page 68: ...ired for warranty defect by anyone other than LORD MicroStrain This warranty does not cover any incidental or consequential damages and is in lieu of all other warranties expressed or implied No representative or person is authorized to assume for LORD MicroStrain any other liability in connection with the sale of LORD MicroStrain products Some states do not allow limitations on how long an implie...

Page 69: ...hipping sent via freight and pre paid LORD MicroStrain will inspect the items returned and issue a refund or credit once the items have been examined and are deemed to be unaltered or undamaged Non standard or custom products may only be returned with approval and a re stocking penalty may be assessed A 30 Day Return must be initiated by receiving a RMA from LORD MicroStrain 10 4 Sales Support Pro...

Page 70: ...o indicate a process or component that requires cautionary measures Situations in which potentially hazardous conditions exist that could result in death or serious injury of workers and or the general public if not avoided Situations where a non immediate or potential hazard presents a lesser threat of injury that could result in minor or moderate injury to workers and or the general public Situa...

Page 71: ...pies Document Where to find it 3DM GX4 45 Software Developers Kit http www microstrain com software development kits sdks 3DM GX4 45 MIP DCP Manual http www microstrain com support docs Product Technical Notes http www microstrain com support docs Product Application Notes http www microstrain com applications Product Datasheets http www microstrain com wireless sensors NIST Calibration Procedures...

Page 72: ...lter An adaptive filter is a linear filter that contains an optimization algorithm that adapts to dynamic conditions These filters are often complex and necessary to compensate for sensor anomalies AHRS Attitude and Heading Reference System A navigation device consisting of sensors on the three primary axis used to measure vehicle dir ection and orientation in space The sensor measurements are typ...

Page 73: ...ctions Also called offset C Calibration To standardize a measurement by determining the deviation standard and applying a cor rection or calibration factor Configuration A general term applied to the sensor indicating how it is set up for data acquisition It includes settings such as sampling rate active measurements measurement settings offsets biases and calibration values Convergance When mathe...

Page 74: ...rements and references from multiple sources Best known estimation filters are the Kalman Filter and Extended Kalman Filter Euler angles Euler angles are three angles use to describe the orientation of an object in space such as the x y and z or pitch roll and yaw Euler angles can also represent a sequence of three elemental rotations around the axes of a coordinate system G GPS Global Positioning...

Page 75: ...al estim ations of what the actual measurements should be L LOS Line of Sight Line of Sight is an acronym used in wireless communications that describes the ideal condition between transmitting and receiving devices in a wireless network As stated it means they are in view of each other with no obstructions M Magnetometer A type of sensor that measures the strength and direction of the local magne...

Page 76: ...he platform causing it to move up or down with respect to the sensor or platform frame origin Position The spatial location of an object PVA Position Velcoity and Attitute Q Quaternion Mathematical notation for representing orientation and rotation of objects in three dimensions with respect to the fixed earth coordinate quaternion Quaternions convert the axis angle rep resentation of the object i...

Page 77: ...process of taking measurements from a sensor or device Sampling rate Rate at which the sensors are sampled Sampling Rate The frequency of sampling Sensor A device that physically or chemically reacts to environmental forces and conditions and pro duces a predictable electrical signal as a result Sigma In statistics sigma is the standard deviation from the mean of a data set Space Vehicle Informati...

Page 78: ...e of position with respect to time Also called speed W WAAS Wide Area Augmentation System An air navigation aid developed to allow aircraft to rely on GPS for all phases of flight including precision approaches to any airport WGS World Geodetic System A protocal for geo referencing such as WGS 84 Y Yaw In navigation yaw is what occurs rotational force is applied at a distance forward or aft from t...

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