teleop_roboboat_tutorial

This page provides a description of how to drive the spawned USV. It assumes you've gone through the preceding tutorials regarding installation, and spawning. It also assumes a basic familiarity with Gazebo.

Thruster Setup

The actuators for the boat we spawned in the previous tutorial are defined by the Gazebo Sim Thruster Class. While there are a number of ways to control heading, with two thrusters we can simply employ differential thrust.

Launching Teleoperation Nodes

Launch the ROS/Gazebo bridge

First, launch the environment:

ros2 launch vrx_gz vrx_environment.launch.py world:=nbpark

To send messages from ROS2 to Gazebo Sim, we must utilize a bridge, specifying the topics and messages we need to send. For the left thruster:

ros2 run ros_gz_bridge parameter_bridge /model/roboboat01/joint/left_engine_propeller_joint/cmd_thrust@std_msgs/msg/Float64]gz.msgs.Double

and for the right thruster:

ros2 run ros_gz_bridge parameter_bridge /model/roboboat01/joint/right_engine_propeller_joint/cmd_thrust@std_msgs/msg/Float64]gz.msgs.Double

Test the Bridges

You can test that the bridges are working by publishing a topic to one or both of the thrusters:

ros2 topic pub /model/roboboat01/joint/left_engine_propeller_joint/cmd_thrust std_msgs/msg/Float64 "data: 150"

using this command you should see your boat going in circles.

Joystick Teleoperation

Config Adjustment

With both bridge commands running, in a separate terminal launch

ros2 launch vrx_gz usv_joy_teleop.py teleop_config:=/home/caguero/vrx2023_ws/src/vrx/vrx_gz/config/roboboat.yaml

The gamepad drives the left and right thrusters directly - similar to a differential drive wheeled robot.

• The L1 button needs to be pressed all the time in addition to the following commands (dead man's switch),
• the left stick up/down axis (axis 1) is mapped to the left thruster forward/reverse,
• the right stick up/down axis (axis 3) is mapped to the right thruster forward/reverse

Therefore, pushing both sticks forward should cause the boat to drive forward.