New Underwater Vehicle

Creating and Integrating a New U/W Vehicle

In this example we will integrate a new robot with the name smilodon.

Import visual and collision mesh files into proejct.

Assumes we start with visual/collision meshes and texture image files.

1. Create a new ROS project: smilodon_gazebo, add a meshes directory and copy the mesh files and image file.
2. May be necessary to edit the visual mesh file to link to the correct texture filename. Simply search for image in the .dae file and replace as necessary.
3. Check the visual mesh by importing the mesh using blender and/or meshlab.

Launch a world, spawn the robot from URDF

Create launch file

Create smilodon_gazebo/launch/smilodon.launch to do the following...

1. Start gazebo with an underwater world.
2. Load the robot URDF (see next step) to the parameter server
3. Spawn the robot in the world
4. Start robot_state_publisher node

Create robot URDF

In smilodon_gazebo/urdf create smilodon_gazebo.xacro to do the following...

1. Create base_link with the rigid-body parameters and the visual/collision meshes
2. Attach the uuv_underwater_object_ros_plugin and specify the hydrodynamic parameters.
3. Attach a gazebo_ros_control plugin.
4. Attache a custom uuv_joint_state_publisher

Note: It is sometimes handy during testing to set <neutrally_buoyant>1</neutrally_buoyant> within the parameters for the uuv_underwater_object_ros_plugin.

Test

roslaunch smilodon_gazebo smilodon.launch 

/tutorials/images/smilodon1.png

Add propulsion

Add thruster propellers, joints and plugins

Edit smilodon_gazebo/urdf/smilodon_gazebo.xacro to add thruster definition macros.

1. Define location of the propellors - can superimpose on vehicle mesh
2. Set the motor constant to map the command (input) to thrust.
3. User the thruster_snippets.xacro definitions which make use of the ThrusterROSPlugin

/tutorials/images/smilodon_props.png

Test by publishing thruster input.

Here is a video of spinning the props.

Illustrates publishing a thruster input

rostopic pub /smilodon/thrusters/0/input uuv_gazebo_ros_plugins_msgs/FloatStamped "header:
  seq: 0
  stamp:
    secs: 0
    nsecs: 0
  frame_id: ''
data: -200.0" 

and monitoring the resulting thrust

rostopic echo /smilodon/thrusters/0/thrust

Test with joystick

The custom joy_thrusterop.py has a hardcoded mapping from joystick axes to each thruster. This allows us to drive the vehicle in an open-loop configuration.

Run the telop with

roslaunch uuv_dave joy_thrusterop.launch

Here is another video showing what to expect.