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Ethernet ROV Locator
Ethernet ROV Locator
  • ROV Locator
  • Overview
  • General Specifications
  • Quick Start for BlueROV
  • Fundamentals Useful to System Designers
    • Sound Reflection and Absorption
    • Multipath
    • Ping Length
    • What to Do About Multipath and Other Issues
    • Clock Drift Expectations
    • Accuracy Expectations
      • Accuracy Test: Topside GPS
      • Accuracy Test: 110 Meter Slant Range
      • Accuracy Test: 295 Meter Slant Range
    • Operation in a Pool
  • Configuring the ROVLe
    • Finding the Configuration Web Page
    • Example Configuration Web Page
    • Live Status Page
    • Setting Device Type
    • Setting the Static IP Address
    • Setting the Fallback IP Address
    • Setting the MAVLink REST Server Parameters
    • Setting the Secondary (GNSS) MAVLink Interface
    • GPS/GNSS Forwarding (Re-tweeting)
    • Magnetic Declination
    • CIMU Calibration Offsets
    • Speed of Sound
    • GNSS Antenna Mounting Rotation
    • Output Messages
    • Configure Simulation
  • System Variants
  • Autosync
    • Autosync Mission Scenarios and Mission Suitability
    • Autosync Availability
    • Autosync GPS/GNSS Output
    • ROVL Channels (Autosync only; Operating Multiple Units in Proximity)
  • Communicating With the ROVL
    • Serial Parameters
    • The Ethernet Interface
      • Tips on How to Find the IP Address Assigned to Your Ethernet Adapter
      • Blue Robotics Discovery Protocol (Ethernet Only)
    • Packet Format
    • Messages from ROVL to Host
      • $USRTH Receiver-Transmitter Relative Angles Message
      • $USTLC Target Location Message
      • $USINF/$USTXT Information Message
      • $USERR Error Message
      • $USNVM Non-Volatile Memory Message
    • Messages from Host to ROVL
      • NMEA-Format Messages to Receiver
      • Valid Commands from Host to ROVL, Serial and Ethernet
      • Valid Commands from Host to ROVL, Ethernet Only
        • Command: DHCP
        • Command: FALLBACK-ADDRESS
        • Command: IP-ADDRESS
        • Command: HOST-ADDRESS
        • Command: MAVLINK-ADDRESS
        • Command: MAVLINK-AUTO-ORIGIN
        • Command: MAVLINK-SYSID
        • Command: PAUSE
        • Command: RESUME
        • Command: RETWEET-GPS
        • Command: RETWEET-GPS-ADDRESS
        • Command: RETWEET-message
        • Command: SEND-ROV-POS-TO-MAP
        • Command: SEND-TOPSIDE-TO-MAP
        • Command: SEND-USRTH
        • Command: SEND-USTLC
        • Command: UNICAST-TO-ME
  • Cerulean Inertial Measurement Unit (CIMU)
    • CIMU Calibration Background
      • CIMU Magnetometer Calibration
      • CIMU Accelerometer Calibration
      • CIMU Gyro Calibration
  • Operating and Accuracy Considerations
  • Multi-Unit Operation (Swarms)
    • Multi-Unit 1:1
    • Multi-Unit 1:2
    • Multi-Unit 2x1:1
  • ROVL Mounting
    • ROV/Deepside Mounting
    • Topside Mounting
    • Simple Topside Deployment Fixture
  • ROVL Wiring
    • Standard Cabling Options
    • ROVL-e PC Board Internal Connections
      • JST-GH Connector Pin 1 Identification
      • Ethernet/Power Connections
      • Serial Connection
      • USB Connection
      • GNSS Compass Main (4-pin) RS-232 Connection
      • GNSS Compass RTK (2-pin) RS-422 Connection
    • Electrical Noise
  • Connecting and Powering Your ROVLe Ethernet Receiver or Transceiver
    • Example Power Injectors
    • Data Connection
    • Example Power/Wi-Fi Setup for Remote Usage
    • Battery
  • Mounting Dimensions
    • Mk II Receiver with Omnitrack Top
    • Transmitter/Transceiver/Receiver with Standard Top
    • Mk III Transcceiver
    • ROVLe Omnitrack Top
    • ROVLe Standard Top
    • Example Mounting Scheme with 3D-Printed Bracket
  • ROVL Coordinate Systems and Angles
    • Definitions
    • NED or "Compass" vs. ENU or "Math" Angles
    • Math to Compass Frame Conversions
    • Transducer Down Orientation
    • Transducer Up Orientation
    • Receiver/Transceiver Orientation Frames
    • Best Operating Envelope
  • Appendix: Math for Computing Remote Latitude/Longitude
    • Receiver & GPS at Topside and Transmitter Deepside
    • Transmitter & GPS Topside and Receiver Deepside
  • Appendix: Factory Usage Command Set
  • Troubleshooting
    • How to Tell if Your Mk II Receiver is Working
    • How to tell if your Mk II Transmitter is working
    • What to do when you find an unresolvable problem when troubleshooting
  • Copyright
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Cerulean Inertial Measurement Unit (CIMU)

The CIMU in your Receiver or Transceiver device calculates the attitude of the device with respect to both gravity and magnetic north. This allows the device to convert its relative estimate of the distance and direction of the ROV to an absolute estimate of the ROV location.

Note that having a good IMU calibration is one of the dominating factors for good system performance.

The CIMUs requires periodic calibration.

  • The accelerometers are subject to slight aging effects, and to temperature effects.

  • The gyros are subject to slight aging effects, and to temperature effects.

  • The magnetometers are subject to variations in the Earth's magnetic field strength and to magnetic disturbances due to electrical currents and and nearby soft iron or other ferrous objects. The closer a disturbance source, the smaller it can be and still affect the north-finding.

The CIMU is recalibrated at your option.

The Earth's magnetic field varies greatly over geographically small areas. This is why we recommend a CIMU magnetometer recalibration every time the system is moved to a different area (rough rule of thumb, recalibrate if you move 50 km or more).

A significant error source for the IMU is often nearby electrical currents. IF the Receiver or Transmitter are mounted on the ROV (and this is NOT typical), a big error source can be the power systems and ferrous materials on the ROV. This is why we recommend a CIMU recalibration every time the device is mounted in a different way on the ROV.

PreviousCommand: UNICAST-TO-MENextCIMU Calibration Background

Last updated 1 month ago