실습 환경 구축 및 시뮬레이션 환경 열기

1. 워크스페이스 내에 필요한 리소스 가져오기

   cd ~/nav2_ws/src
   git clone <https://github.com/Adlink-ROS/ros2_object_msgs.git>
   git clone <https://github.com/Adlink-ROS/BT_ros2.git>
   

2. 워크스페이스 내 패키지 빌드

   cd ~/nav2_ws
   colcon build --symlink-install --packages-select object_msgs
   source ~/nav2_ws/install/local_setup.bash
   
   rosdep install --from-paths src/BT_ros2 --ignore-src -r -y
   colcon build --symlink-install --packages-select bt_ros2
   source ~/nav2_ws/install/local_setup.bash
   

3. mememan_world.model 환경을 사용하기 위해 파일 수정

   • ~/nav2_ws/src/neuronbot2/neuronbot2_gazebo/launch/**neuronbot2_world.launch.py**

     ...
     
         world = os.path.join(
             **get_package_share_directory('neuronbot2_gazebo'),**
             'worlds',
             **'mememan_world.model'**
         )
     
     ...
     

   • ~/nav2_ws/src/neuronbot2/neuronbot2_nav/launch/**bringup_launch.py**

     ...
     
     **my_map_file = 'mememan.yaml'**
     
     ...
     

4. 시뮬레이션 환경 열기

   # terminal 1
   ros2 launch neuronbot2_gazebo neuronbot2_world.launch.py
   
   # terminal 2
   ros2 launch neuronbot2_nav bringup_launch.py use_sim_time:=true
   

[실습 1] 정해진 경유지 반복하여 방문하기

ros2 launch bt_ros2 bt_ros2.launch.py

<root main_tree_to_execute = "MainTree">
    <BehaviorTree ID="MainTree">
        <Repeat num_cycles="3">
            <Sequence>
                <!-- The goal value="position-x;position-y;orientaion-z;orientation-w" -->
                <SetBlackboard output_key="Goal_a" value="-0.579;-1.341;0.0;1.0" />
                <SetBlackboard output_key="Goal_b" value="5.214;-1.533;0.0;1.0" />
                <SetBlackboard output_key="Goal_c" value="-1.588;1.253;0.0;1.0" />
                <Sequence>
                    <SubTree ID="MoveRobot" target="Goal_a" />
                    <SubTree ID="MoveRobot" target="Goal_b" />
                    <SubTree ID="MoveRobot" target="Goal_c" />
                </Sequence>
            </Sequence>
        </Repeat>
    </BehaviorTree>

    <BehaviorTree ID="MoveRobot">
        <Sequence name="SetGoal">
            <Nav2Client goal="{target}" />
        </Sequence>
    </BehaviorTree>
</root>

• 메인 트리 구조 (MainTree)
  • "MainTree"라는 ID를 가진 주 행동 트리가 정의되어 있음
  • 이 트리는 전체 시퀀스를 3번 반복 (Repeat 노드)
• 목표 설정
  • 세 개의 목표 위치(Goal_a, Goal_b, Goal_c)가 SetBlackboard 노드를 통해 정의됨
  • 각 목표는 x, y 위치와 z, w 방향을 포함
• 이동 시퀀스
  • 정의된 세 목표 지점으로 순차적으로 이동
  • 각 이동은 "MoveRobot" 서브트리를 호출하여 실행

[실습 2] InterruptEvent 활용

# terminal 1
ros2 run bt_ros2 bt_ros2 --ros-args -p bt_xml:=$HOME/nav2_ws/src/BT_ros2/bt_xml/bt_nav_mememan_interrupt.xml

# terminal 2
ros2 topic pub -1 /interrupt_event std_msgs/msg/String data:\\ \\'gohome\\'

<root main_tree_to_execute = "MainTree">
    <BehaviorTree ID="MainTree">
        <Sequence>
            <SetBlackboard output_key="Goal_a" value="-0.579;-1.341;0.0;1.0" />
            <SetBlackboard output_key="Goal_b" value="5.214;-1.533;0.0;1.0" />
            <SetBlackboard output_key="Goal_c" value="-1.588;1.253;0.0;1.0" />
            <Fallback>
                <ReactiveSequence>
                    <InterruptEvent event="gohome"/>
                    <Repeat num_cycles="10">
                        <Sequence>
                            <SubTree ID="MoveRobot" target="Goal_a" />
                            <SubTree ID="MoveRobot" target="Goal_b" />
                        </Sequence>
                    </Repeat>
                </ReactiveSequence>
                <Sequence>
                    <SubTree ID="MoveRobot" target="Goal_c" />
                </Sequence>
            </Fallback>
        </Sequence>
    </BehaviorTree>

    <BehaviorTree ID="MoveRobot">
        <Sequence name="SetGoal">
            <Nav2Client goal="{target}" />
        </Sequence>
    </BehaviorTree>
</root>