SLAM

Simultaneous localization and mapping (SLAM) is a method of generating a map and tracking the robot's location within the 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 slam_toolbox package to map our environment. 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 SLAM

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 SLAM

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

5. Drive the robot around the world until the entire map has been generated

SLAM in simulation

6. Save the map

ros2 run nav2_map_server map_saver_cli -f "map_name" \
--ros-args -p map_subscribe_transient_local:=true -r __ns:=/j100_0001