Localization

Localization is a method of tracking the robot's location within an existing map. It is generally done using laser scan data from a 2D LIDAR, and the robot's odometry. For this demo we are using the Nav2 package launch localization.

This tutorial will use the Clearpath simulator, but will work on a physical robot too. We will be using a J100 with a Hokuyo UST10 attached to the front of the robot.

J100 YAML

serial_number: j100-0001
version: 0
system:
  username: administrator
  hosts:
    - hostname: cpr-j100-0001
      ip: 192.168.131.1
  ros2:
    namespace: j100_0001
    domain_id: 0
    middleware:
      implementation: rmw_fastrtps_cpp
  extras:
    ros_parameters:
      linear.x.max_velocity": 2.0
      linear.x.min_velocity": -2.0
      linear.x.max_acceleration": 20.0
      linear.x.min_acceleration": -20.0
      angular.z.max_velocity": 4.0
      angular.z.min_velocity": -4.0
      angular.z.max_acceleration": 25.0
      angular.z.min_acceleration": -25.0
platform:
  controller: ps4
  decorations:
    front_bumper:
      enabled: true
      model: default
      xyz: [0.0, 0.0, 0.0]
      rpy: [0.0, 0.0, 0.0]
      extension: 0.0
    rear_bumper:
      enabled: true
      model: default
      xyz: [0.0, 0.0, 0.0]
      rpy: [0.0, 0.0, 0.0]
      extension: 0.0
    top_plate:
      enabled: true
      model: default
      xyz: [0.0, 0.0, 0.0]
      rpy: [0.0, 0.0, 0.0]
sensors:
  lidar2d:
    - model: hokuyo_ust
      urdf_enabled: true
      launch_enabled: true
      parent: front_mount
      xyz: [0.0, 0.0, 0.0]
      rpy: [0.0, 0.0, 0.0]
      ros_parameters:
        urg_node:
          angle_min: -1.5707
          angle_max: 1.5707

tip

Make sure you have installed the simulator before starting this tutorial. Take a look at the installation guide for details.

Launching the simulation and localization

1. Move the robot.yaml file to your setup folder ($HOME/clearpath by default).

2. Launch the simulation

ros2 launch clearpath_gz simulation.launch.py

Click on the orange play button in the bottom left corner to start the simulation.

3. In another terminal, launch RViz

ros2 launch clearpath_viz view_navigation.launch.py namespace:=j100_0001

4. In another terminal, launch localization

ros2 launch clearpath_nav2_demos localization.launch.py setup_path:=$HOME/clearpath/ use_sim_time:=true

The default map used by localization.launch.py is a map of the simulated warehouse world. If you are using a custom map, pass it in with the map launch argument:

ros2 launch clearpath_nav2_demos localization.launch.py setup_path:=$HOME/clearpath/ use_sim_time:=true map:=/path/to/my/map.yaml

5. Set the initial pose of the robot

Use the 2D Pose Estimate tool in RViz to set the initial pose of the robot. You can now drive the robot and it will calculate its position on the map.

Localization in simulation