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DVL-75
DVL-75
  • DVL-75
  • Overview
    • General Specifications
    • General Use Cases
    • The Basic System
    • System Components
    • Comparison of Tracker 650 and DVL-75
  • Usage Considerations and Scenarios
    • General Usage
    • Scenario: GPS Emulation
    • Scenario: Holding Position
    • Scenario: Autonomous Waypoint Navigation
    • Scenario: Returning to a Series of Known Positions
    • Scenario: Returning to Home
    • Scenario: Using GPS Assist
    • Scenario: Doing Your Own Dead Reckoning
    • Additional Connection Possibilities
    • General Hints and Tips
    • Operation in a Pool
  • Using MAVLink and BlueOS for Position Hold on a BlueROV2
    • ArduPilot Parameters
    • DVL Setup for MAVlink Support
  • Using Other Than the Bottom for the DVL (Side-Tracking Capability)
    • Side-Tracking Capability Design Use-Cases
    • Side-Tracking Capability Considerations
  • Mounting the DVL Components
    • Sensor Head Typical Mounting
    • Sensor Head Side-Tracking Mounting Alignment
    • All-in-One and Most-in-One Mounting Considerations
    • Mounting the Electronics Stack
    • Mounting an Auxiliary GPS
  • Assembling the Electronics Stack
    • Cerulean 300m Electronics Enclosure Assembly
  • Inertial Measurement Unit (IMU)
    • Baseline IMU Calibrations
    • Baseline IMU Background
    • Baseline IMU Blind Initial Calibration Procedure
    • Baseline IMU Status-Assisted Initial Calibration Procedure
    • Baseline IMU Calibration for Each Mission or Each Time Power is Applied
    • Upgraded IMU Calibration for Each Mission or Each Time Power is Applied
  • Communicating with the DVL
    • Factory Defaults and Default Messages
    • The Ethernet Interface
    • Tips on How to Find the IP Address Assigned to Your Ethernet Adapter
    • The Serial Interface
    • Resetting the Communications Parameters to Factory Default
    • What Do the LEDs Mean?
    • Outgoing Message Formats, DVL to Host
      • $GPRMC: NMEA standard Recommended Minimum GPS/Transit Data
      • $DVEXT: DVL Extended Data
      • $DVPDL: DVL Position and Angle Deltas Message
      • Freeform Error and Informational messages ($DVTXT)
      • Re-Tweeted GPS Messages
      • Re-Tweeted IMU Messages (IMU Raw Data)
      • $DVKFA, $DVKFB Kalman Filter Support Messages
        • Driving your own Kalman Filter
    • Commands Accepted by the DVL
      • $GPRMC
      • SET-POSITION
      • CONFIGURATION
      • SUPPRESS-GPS
      • DECLINATION
      • SET-SPEED-OF-SOUND
      • SET-VELOCITY-ADJUSTMENT
      • SEND-GPRMC
      • SEND-DVEXT
      • SEND-DVKFA
      • SEND-DVKFB
      • SEND-FREEFORM
      • SEND-DVPDL
      • RETWEET-GPS
      • RETWEET-IMU
      • SET-SENSOR-ORIENTATION
      • GRAB-IMU-CAL
      • VOID-IMU-CAL
      • BAUD-RATE
      • IP-ADDRESS
      • HOST-ADDRESS
      • MAVLINK-ADDRESS
      • FALLBACK-ADDRESS
      • UNICAST-TO-ME
      • PAUSE
      • RESUME
      • REBOOT
    • Blue Robotics Ping360 Discovery Protocol (Ethernet Only)
    • ARP (Address Resolution Protocol)
    • DHCP (Dynamic Host Configuration Protocol)
    • Ping (Internet Control Message Protocol Ping)
    • Mechanical Drawings
      • Mounting Dimensions, Sensor Head
      • Mounting Dimensions, Electronics Stack
      • RAM Mount Adapter Plate
      • Electronics Stack Assembly Drawing
      • Mounting Bracket for 300m Electronics Enclosure
      • Mounting Bracket for Sensor Head or Electronics Enclosure, fits BlueROV2 Heavy Thruster Guard
      • Mounting Bracket for All-in-One Enclosure, fits BlueROV2 Heavy Thruster Guard
      • Mounting Dimensions, Cerulean 300m Enclosure
      • Mounting Dimensions for the Cerulean All-in-One Enclosure
      • Mounting Dimensions, Cerulean GPS
  • Electrical Drawings
    • Serial Cable Supplied with Baseline Electronics Stack
    • DVL Serial Connection Example
    • Power over Ethernet (POE) Cabling
    • Standard Ethernet Pinouts
    • Optional GPS Wiring
    • Sensor Head Wiring
    • Using External Power with Serial Cable
    • Serial to USB Interface Using Blue Robotics BLUART Board
  • CAD Models
  • Appendix – Coordinate Systems
  • Copyright
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  1. Inertial Measurement Unit (IMU)

Baseline IMU Status-Assisted Initial Calibration Procedure

This procedure applies only to the baseline IMU and should be followed if you can see the calibration state.

The extended data message has a field to show the calibration state of the individual IMU components (see message definition). To take advantage of this information, your IMU dance changes to go like this (for initial mounting calibrations only; this should not be needed for each start-up):

  • Set up where you can watch the calibration status as you move the ROV (or whatever the DVL is mounted to).

  • Wait for the gyroscope status to reach “3” (second digit of IMU status). This can usually be done by just leaving the unit sit still. If on a rocking boat or other moving platform and the gyro status does not reach “3” within 60 seconds, go on to the next steps.

  • Imagine the DVL head is enclosed in a cube (or maybe it is really mounted in a cube-like structure like a Blue ROV). Lay each face of the cube containing the head down on a stable platform for about 5 seconds per face (i.e., you are laying on six orthogonal faces). Move smoothly between each position, and don’t “thunk” the system when you set it on any face. Watch the accelerometer status (third digit of IMU status) and repeat this a couple of times until the status reaches “3”. If you’ve done three sets of faces without achieving a “3” status, go to the next step.

  • Imagine the DVL head is enclosed in a cube (or maybe it is really mounted in a cube-like structure like a Blue ROV). Lay each face of the cube containing the head down on a stable platform for about 5 seconds per face (i.e., you are laying on six orthogonal faces). Move smoothly between each position, and don’t “thunk” the system when you set it on any face. Watch the accelerometer status (third digit of IMU status) and repeat this a couple of times until the status reaches “3”. If you’ve done three sets of faces without achieving a “3” status, go to the next step.

  • Rotate the system about its vertical axis a few times, back and forth, being sure to rotate at least 500 degrees each direction. Flip the system upside down and make the same kind of rotations. Try to move smoothly and not too slow or fast (about 2 to 4 seconds for a 360-degree rotation is good). Watch the magnetometer (fourth digit of IMU status) until the status reaches “3”. If you’ve done three sets of right-side-up and upside-down rotations without achieving a “3” status, go to the next step.

  • Wave the system around randomly until the system status (all digits) reaches “3333”. If it does not reach three within about twenty seconds, go back to the beginning and repeat the steps.

  • Note that it is normal for the system status to drop below “3333” during operation. This is usually nothing to worry about. The key is to achieve the “3333” status at least once.

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Last updated 3 years ago