Add Mecanum vehicle example

doc/index.rst

@@ -336,6 +336,13 @@ When the Gazebo world is launched you can run some of the following commands to
   ros2 run gz_ros2_control_demos example_tricycle_drive
   ros2 run gz_ros2_control_demos example_ackermann_drive
 
+To run the Mecanum mobile robot run the following commands to drive it from the keyboard:
+
+.. code-block:: shell
+
+  ros2 launch gz_ros2_control_demos mecanum_drive_example.launch.py
+  ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -p stamped:=true
+
 Gripper
 -----------------------------------------------------------
 

gz_ros2_control_demos/config/mecanum_drive_controller.yaml

@@ -0,0 +1,25 @@
+controller_manager:
+  ros__parameters:
+    update_rate: 100  # Hz
+    use_sim_time: true
+
+    joint_state_broadcaster:
+      type: joint_state_broadcaster/JointStateBroadcaster
+
+    mecanum_drive_controller:
+      type: mecanum_drive_controller/MecanumDriveController
+
+mecanum_drive_controller:
+  ros__parameters:
+    reference_timeout: 1.0 # max time between command messages before the vehicle should stop
+    front_left_wheel_command_joint_name: "front_left_wheel_joint"
+    front_right_wheel_command_joint_name: "front_right_wheel_joint"
+    rear_right_wheel_command_joint_name: "rear_right_wheel_joint"
+    rear_left_wheel_command_joint_name: "rear_left_wheel_joint"
+    kinematics:
+        base_frame_offset: { x: 0.0, y: 0.0, theta: 0.0 }
+        wheels_radius: 0.3
+        sum_of_robot_center_projection_on_X_Y_axis: 0.55
+    base_frame_id: "base_link"
+    odom_frame_id: "odom"
+    enable_odom_tf: true

gz_ros2_control_demos/launch/mecanum_drive_example.launch.py

@@ -0,0 +1,116 @@
+# Copyright 2021 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from launch import LaunchDescription
+from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription
+from launch.actions import RegisterEventHandler
+from launch.event_handlers import OnProcessExit
+from launch.launch_description_sources import PythonLaunchDescriptionSource
+from launch.substitutions import Command, FindExecutable, LaunchConfiguration, PathJoinSubstitution
+
+from launch_ros.actions import Node
+from launch_ros.substitutions import FindPackageShare
+
+
+def generate_launch_description():
+    # Launch Arguments
+    use_sim_time = LaunchConfiguration('use_sim_time', default=True)
+
+    # Get URDF via xacro
+    robot_description_content = Command(
+        [
+            PathJoinSubstitution([FindExecutable(name='xacro')]),
+            ' ',
+            PathJoinSubstitution(
+                [FindPackageShare('gz_ros2_control_demos'),
+                 'urdf', 'test_mecanum_drive.xacro.urdf']
+            ),
+        ]
+    )
+    robot_description = {'robot_description': robot_description_content}
+    robot_controllers = PathJoinSubstitution(
+        [
+            FindPackageShare('gz_ros2_control_demos'),
+            'config',
+            'mecanum_drive_controller.yaml',
+        ]
+    )
+
+    node_robot_state_publisher = Node(
+        package='robot_state_publisher',
+        executable='robot_state_publisher',
+        output='screen',
+        parameters=[robot_description]
+    )
+
+    gz_spawn_entity = Node(
+        package='ros_gz_sim',
+        executable='create',
+        output='screen',
+        arguments=['-topic', 'robot_description',
+                   '-name', 'mecanum_vehicle', '-allow_renaming', 'true'],
+    )
+
+    joint_state_broadcaster_spawner = Node(
+        package='controller_manager',
+        executable='spawner',
+        arguments=['joint_state_broadcaster'],
+    )
+    mecanum_drive_controller_spawner = Node(
+        package='controller_manager',
+        executable='spawner',
+        arguments=[
+            'mecanum_drive_controller',
+            '--param-file',
+            robot_controllers,
+            ],
+    )
+
+    # Bridge
+    bridge = Node(
+        package='ros_gz_bridge',
+        executable='parameter_bridge',
+        arguments=['/clock@rosgraph_msgs/msg/Clock[gz.msgs.Clock'],
+        output='screen'
+    )
+
+    return LaunchDescription([
+        # Launch gazebo environment
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(
+                [PathJoinSubstitution([FindPackageShare('ros_gz_sim'),
+                                       'launch',
+                                       'gz_sim.launch.py'])]),
+            launch_arguments=[('gz_args', [' -r -v 4 empty.sdf'])]),
+        RegisterEventHandler(
+            event_handler=OnProcessExit(
+                target_action=gz_spawn_entity,
+                on_exit=[joint_state_broadcaster_spawner],
+            )
+        ),
+        RegisterEventHandler(
+            event_handler=OnProcessExit(
+                target_action=joint_state_broadcaster_spawner,
+                on_exit=[mecanum_drive_controller_spawner],
+            )
+        ),
+        bridge,
+        node_robot_state_publisher,
+        gz_spawn_entity,
+        # Launch Arguments
+        DeclareLaunchArgument(
+            'use_sim_time',
+            default_value=use_sim_time,
+            description='If true, use simulated clock'),
+    ])

gz_ros2_control_demos/package.xml

@@ -44,6 +44,7 @@
   <exec_depend>imu_sensor_broadcaster</exec_depend>
   <exec_depend>joint_state_broadcaster</exec_depend>
   <exec_depend>joint_trajectory_controller</exec_depend>
+  <exec_depend>mecanum_drive_controller</exec_depend>
   <exec_depend>ros2controlcli</exec_depend>
   <exec_depend>tricycle_controller</exec_depend>
   <exec_depend>velocity_controllers</exec_depend>