Add ros2 launch and make it the default

Dockerfile

@@ -25,6 +25,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     ros-${ROS_DISTRO}-geometry-msgs \
     ros-${ROS_DISTRO}-std-msgs \
     ros-${ROS_DISTRO}-sensor-msgs \
+    ros-${ROS_DISTRO}-launch-ros \
     python3-smbus \
     && rm -rf /var/lib/apt/lists/*
 
@@ -42,4 +43,4 @@ COPY docker-entrypoint.sh /docker-entrypoint.sh
 RUN chmod +x /docker-entrypoint.sh
 
 ENTRYPOINT ["/docker-entrypoint.sh"]
-CMD ["ros2", "run", "my_robot", "motor_controller"]
+CMD ["ros2", "launch", "my_robot", "robot.launch.py"]

README.md

@@ -165,7 +165,7 @@ Replace `matt` with the username configured in [ansible/inventory.ini](ansible/i
 
 ## Launching
 
-The container needs access to the I²C bus that the motor controller is wired to. Pass only that device rather than running the container in privileged mode:
+The default `CMD` starts both nodes together via the launch file. The container needs access to the I²C bus — pass only that device rather than running privileged:
 
 ```bash
 docker run --rm \
@@ -175,11 +175,11 @@ docker run --rm \
   my_robot:latest
 ```
 
-If your board exposes the motor controller on a different bus (check with `ls /dev/i2c-*` on the host), substitute the correct device node (e.g. `--device /dev/i2c-0`).
+If your board exposes the controller on a different bus (check with `ls /dev/i2c-*` on the host), substitute the correct device node (e.g. `--device /dev/i2c-0`).
 
-### Camera orientation node
+### Overriding parameters at launch
 
-Override the default `CMD` to run the camera orientation node instead:
+Launch arguments can be appended after the image name:
 
 ```bash
 docker run --rm \
@@ -187,63 +187,22 @@ docker run --rm \
   --device /dev/i2c-1 \
   --env ROS_DOMAIN_ID=0 \
   my_robot:latest \
-  ros2 run my_robot camera_orientation
+  ros2 launch my_robot robot.launch.py \
+    wheel_base:=0.25 max_speed:=0.8 tilt_center_deg:=45.0
 ```
 
-#### Overriding parameters at launch
+Available launch arguments:
 
-```bash
+| Argument | Default | Description |
-docker run --rm \
+|---|---|---|
-  --network=host \
+| `wheel_base` | `0.3` | Distance between left and right wheels (m) |
-  --device /dev/i2c-1 \
+| `max_speed` | `1.0` | Maximum motor speed in library units |
-  --env ROS_DOMAIN_ID=0 \
+| `pan_center_deg` | `90.0` | Pan angle at startup and shutdown (degrees) |
-  my_robot:latest \
+| `tilt_center_deg` | `60.0` | Tilt angle at startup and shutdown (degrees) |
-  ros2 run my_robot camera_orientation \
-    --ros-args -p pan_center_deg:=90.0 -p tilt_center_deg:=45.0
-```
-
-#### Commanding the camera from the host
-
-Pan to centre (90°) and tilt to 30°:
-
-```bash
-ros2 topic pub --once /joint_command sensor_msgs/msg/JointState \
-  "{name: ['pan', 'tilt'], position: [1.5708, 0.5236]}"
-```
-
-You can command a single axis by omitting the other joint name:
-
-```bash
-# Pan only
-ros2 topic pub --once /joint_command sensor_msgs/msg/JointState \
-  "{name: ['pan'], position: [0.0]}"
-```
-
-#### Verifying orientation state
-
-```bash
-ros2 topic echo /joint_states
-```
-
----
-
-### Overriding parameters at launch (motor controller)
-
-ROS 2 parameters can be passed through `--ros-args`:
-
-```bash
-docker run --rm \
-  --network=host \
-  --device /dev/i2c-1 \
-  --env ROS_DOMAIN_ID=0 \
-  my_robot:latest \
-  ros2 run my_robot motor_controller \
-    --ros-args -p wheel_base:=0.25 -p max_speed:=0.8
-```
 
 ### Sending velocity commands from the host
 
-With the container running, publish a `cmd_vel` message from another terminal (requires ROS 2 installed on the host or a second container on the same network):
+With the container running, publish from another terminal (requires ROS 2 on the host or a second container on the same network):
 
 ```bash
 # Drive forward at 0.2 m/s
@@ -259,10 +218,31 @@ ros2 topic pub --once /cmd_vel geometry_msgs/msg/Twist \
   "{linear: {x: 0.0}, angular: {z: 0.0}}"
 ```
 
+### Commanding the camera from the host
+
+Pan to centre (90°) and tilt to 30°:
+
+```bash
+ros2 topic pub --once /joint_command sensor_msgs/msg/JointState \
+  "{name: ['pan', 'tilt'], position: [1.5708, 0.5236]}"
+```
+
+A single axis can be commanded by omitting the other joint name:
+
+```bash
+# Pan only
+ros2 topic pub --once /joint_command sensor_msgs/msg/JointState \
+  "{name: ['pan'], position: [0.0]}"
+```
+
 ### Verifying telemetry
 
 ```bash
+# Wheel speeds
 ros2 topic echo /current_wheel_speeds
+
+# Camera orientation
+ros2 topic echo /joint_states
 ```
 
 ---
@@ -277,6 +257,8 @@ ros2 topic echo /current_wheel_speeds
 │   └── my_robot/
 │       ├── package.xml         # ROS package manifest
 │       ├── setup.py            # ament_python build definition
+│       ├── launch/
+│       │   └── robot.launch.py               # Starts both nodes together
 │       └── my_robot/
 │           ├── __init__.py
 │           ├── motor_controller_node.py      # Differential-drive motor control

src/my_robot/launch/robot.launch.py

@@ -0,0 +1,45 @@
+from launch import LaunchDescription
+from launch.actions import DeclareLaunchArgument
+from launch.substitutions import LaunchConfiguration
+from launch_ros.actions import Node
+
+
+def generate_launch_description():
+    return LaunchDescription([
+
+        # ── Motor controller arguments ────────────────────────────────────
+        DeclareLaunchArgument('wheel_base', default_value='0.3',
+                              description='Distance between left and right wheels (m)'),
+        DeclareLaunchArgument('max_speed',  default_value='1.0',
+                              description='Maximum motor speed in library units'),
+
+        # ── Camera orientation arguments ──────────────────────────────────
+        DeclareLaunchArgument('pan_center_deg',  default_value='90.0',
+                              description='Pan angle at startup and shutdown (degrees)'),
+        DeclareLaunchArgument('tilt_center_deg', default_value='60.0',
+                              description='Tilt angle at startup and shutdown (degrees)'),
+
+        # ── Nodes ─────────────────────────────────────────────────────────
+        Node(
+            package='my_robot',
+            executable='motor_controller',
+            name='motor_controller',
+            parameters=[{
+                'wheel_base': LaunchConfiguration('wheel_base'),
+                'max_speed':  LaunchConfiguration('max_speed'),
+            }],
+            output='screen',
+        ),
+
+        Node(
+            package='my_robot',
+            executable='camera_orientation',
+            name='camera_orientation',
+            parameters=[{
+                'pan_center_deg':  LaunchConfiguration('pan_center_deg'),
+                'tilt_center_deg': LaunchConfiguration('tilt_center_deg'),
+            }],
+            output='screen',
+        ),
+
+    ])

src/my_robot/package.xml

@@ -10,6 +10,8 @@
   <exec_depend>geometry_msgs</exec_depend>
   <exec_depend>std_msgs</exec_depend>
   <exec_depend>sensor_msgs</exec_depend>
+  <exec_depend>launch</exec_depend>
+  <exec_depend>launch_ros</exec_depend>
 
   <buildtool_depend>ament_python</buildtool_depend>
 

src/my_robot/setup.py

@@ -9,6 +9,7 @@ setup(
     data_files=[
         ('share/ament_index/resource_index/packages', ['resource/' + package_name]),
         ('share/' + package_name, ['package.xml']),
+        ('share/' + package_name + '/launch', ['launch/robot.launch.py']),
     ],
     install_requires=['setuptools'],
     zip_safe=True,