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Nav tools

Project Description

This package contains tools to convert msgs between data types. Currently, it also houses range-based positioning tools. This package has the following highlights

  • Convert data in WGS84 from sensor_msgs::NavSatFix to data in UTM NED & medusa_msgs::Measurement
  • Convert state from auv_msgs::NavigationStatus to medusa_msgs::mState
  • Convert state from auv_msgs::NavigationStatus to nav_msgs::Odometry
  • Convert Ranges from single-beacon to position update using EKF
  • Convert Georeferenced USBL position fix to position update

Getting Started

Installation

Pkg nav_tools comes as part of the medusa_vx stack.

Gnss2Utm

This node converts data in WGS84 from sensor_msgs::NavSatFix to UTM NED medusa_msgs::Measurement format

Configuration

This section explains how to write the node configuration file. A sample is given below

node_frequency: 10
topics:
  subscribers: [ "/measurement/gnss" ]
  publishers: [ "/measurement/position" ]

ROS Node Parameters

  1. node_frequency: parameter of type double
  2. Define the node output frequency
  3. topics/subscribers: parameter of type string[1]
  4. Defines the input topic to receive position in Lat/Lon, WGS84 format.
  5. topics/publishers: parameters of type string[1]
  6. Defines topic to output position in UTM NED

Launching the Nodes

An example launch file is provided below where nav_tools/gnss2utm node is being launched.

<?xml version="1.0"?>
<launch>
    <node pkg="nav_tools" type="gnss_to_utm" name="gnss2utm" respawn="true" output="screen">
        <rosparam command="load" file="$(find nav_tools)/config/gnss2utm.yaml"/>
    </node>
</launch>

AuvState2mState

This node converts state in auv_msgs::NavigationStatus to state in medusa_msgs::mState. Also need inside_pressure data for mState.

Configuration

This section explains how to write the node configuration file. A sample is given below

node_frequency: 10
topics:
  subscribers: [ "/nav/filter/state", "/drivers/inside_pressure/data" ]  
  publishers:  [ "/State" ]

  1. node_frequency: node output frequency

  2. topics/subscribers: parameter of type string[2]

  3. topic[1] - state: receives state of type auv_msgs::NavigationStatu

  4. topic[2] - inside_pressure: receives inside_pressure data

  5. topics/publishers: parameter of type string[1]

  6. topic[1] - state: publishes state of type medusa_msgs::mState

Launching the Nodes

An example launch file is provided below where nav_tools/auvstate2mstate node is being launched.

<?xml version="1.0"?>
<launch>
    <node pkg="nav_tools" type="auvstate_to_mstate" name="auvstate2mstate" respawn="true" output="screen">
        <rosparam command="load" file="$(find nav_tools)/config/auvstate2mstate.yaml"/>
    </node>
</launch>

AuvState2Odom

This node converts state in auv_msgs::NavigationStatus to nav_msgs::Odometry.

Configuration

This section explains how to write the node configuration file. A sample is given below

node_frequency: 10
topics:
  subscribers: [ "/nav_filter/state" ]
  publishers:  [ "/nav_filter/state_odom" ]

  1. node_frequency: node output frequency

  2. topics/subscribers: parameter of type string[1]

  3. receives state of type auv_msgs::NavigationStatus

  4. topics/publishers: parameter of type string[1]

  5. publishes state of type nav_msgs::Odometry

Launching the Nodes

An example launch file is provided below where nav_tools/auvstate2odom node is being launched.

<?xml version="1.0"?>
<launch>
    <node pkg="nav_tools" type="auvstate_to_odom" name="auvstate2odom" respawn="true" output="screen">
        <rosparam command="load" file="$(find nav_tools)/config/auvstate2odom.yaml"/>
    </node>
</launch>

Usbl2Pos

This node takes in georeferences usbl position fix and converts it to position updates of the filter. It can be deployed in two ways

Scenario 1: Inverted-USBL In this scenario, the underwater vehicle localizes itself with respect to an anchor, whose precise global position is known. The usbl onboard the vehicle receives the georeferenced position of the anchor and the usbl-fix. The vehicle uses these two information to estimate its position using simple geometry.

Scenario 2: Tracking with USBL In this scenario, the anchor, whose precise global position is known, tracks underwater vehicles using USBL fixes. The anchor receives the usbl-fix of the underwater vehicle and uses its own position to estimate the position of the underwater vehicle.

Configuration

node_frequency: 10
topics:
  subscribers: [
    "/acomms/measurement/usbl_fix", "/acomms/convert/state"
  ]
  publishers: [ "/measurement/position" ]
t_sync: 2
fix_type: false
meas_noise: 0.001

  1. node_frequency: node output frequency

  2. topics/subscribers: parameter of type string[2]

  3. defines the input topics -
  4. usblfix topic to receive USBL position fixes in medusa_msgs::mUSBLFix

  5. state topic to receive the state of the vehicle or anchor state in auv_msgs::NavigationStatus

  6. t_sync: parameter of type double

  7. time (secs) after which "Range Only" and "Bearing/Elevation" medusa_msgs::mUSBLFix fixes go out of sync

  8. fix_type: parameter of type bool

  9. if set false, vehicle acts as an achor, estimates other vehicles position i.e. scenario 1
  10. if set true, vehicle estimates its position with respect to an anchor i.e. scenario 2

Launching the Nodes

An example launch file is provided below where nav_tools/usblfix2pos node is being launched.

<?xml version="1.0"?>
<launch>
    <node pkg="nav_tools" type="usblfix_to_pos" name="usblfix2pos" respawn="true" output="screen">
        <rosparam command="load" file="$(find nav_tools)/config/usblfix2pos.yaml"/>
    </node>
</launch>

Range2Pos

This node converts ranges from a single beacon to a position measurement using an Extended Kalman Filter.

Configuration

This section explains how to write the node configuration file. A sample is given below

node_frequency: 10
t_sync: 2
topics:
    subscribers: [ "/sensors/usbl", "/nav/filter/state" ]
    publishers: [ "/measurement/position" ]
beacon:
    position: [4290771, 491886]

  1. node_frequency: node output frequency

  2. topics/subscribers: parameter of type string[3]

  3. Defines the input topics -
  4. range topic to receive range only USBL fixes in medusa_msgs::mUSBLFix
  5. state topic to receive state from navigation system in auv_msgs::NavigationStatus

  6. beacon topic to receive beacon state

  7. topics/publishers: parameter of type string[1]

  8. publishes position update of type medusa_msgs::Measurement

  9. beacon/position: State of stationary beacon position in UTM NED

Launching the Nodes

An example launch file is provided below where nav_tools/auvstate2mstate node is being launched.

<?xml version="1.0"?>
<launch>
    <node pkg="nav_tools" type="usblfix_to_pos" name="range2pos" respawn="true" output="screen">
        <rosparam command="load" file="$(find nav_tools)/config/range2pos.yaml"/>
    </node>
</launch>
Last update: May 30, 2022
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