在ros2下使用ros1_bridge与ros1自定义消息桥接

在ros2下使用ros1_bridge与ros1自定义消息桥接

示例环境

操作系统：ubuntu 20.04 amd64

ros版本：noetic

ros2版本：foxy

ros1示例代码

1. 创建ros1的工作空间catkin_ws，功能包custom_msgs，并创建一个msg文件TestNoetic.msg

   TestNoetic.msg文件内容如下:

   string test_str1
   int32 test_int1
   

   编译功能包，由于大家对ros1很熟悉了，所以此处不在介绍ros1编译的细节；

2. 创建ros2的工作空间colcon_ws，功能包custom_msgs，并创建一个msg文件TestFoxy.msg

   ros2创建包指令:

   ros2 pkg create --build-type ament_cmake custom_msgs
   

   TestFoxy.msg文件内容如下:

   string test_str2
   int32 test_int2
   

   注意事项：ros2的msg文件命名有正则表达式的规定，要以大写字母开头，文件内容中的每个变量不可以存在大写字母，更详细的规则请参考官方文档

3. 由于示例中要桥接的消息的文件名和内部变量名不一样，所以需要定义映射文件mapping_rules.yaml

   -
     ros1_package_name: 'custom_msgs'
     ros1_message_name: 'TestNoetic'
     ros2_package_name: 'custom_msgs'
     ros2_message_name: 'TestFoxy'
     fields_1_to_2:
       test_str1: 'test_str2'
       test_int1: 'test_int2'
   

   此映射文件放在package.xml同级目录下即可，此文件中只需要在两个包名或msg名或者变量名不相同时给出，如果名称都相同可以省略，如果存在此文件，则CMakeLists.txt如下：

   cmake_minimum_required(VERSION 3.5)
   project(custom_msgs)
   
   # Default to C++14
   if(NOT CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 14)
   endif()
   
   if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
     add_compile_options(-Wall -Wextra -Wpedantic)
   endif()
   
   find_package(ament_cmake REQUIRED)
   find_package(builtin_interfaces REQUIRED)
   find_package(rosidl_default_generators REQUIRED)
   
   rosidl_generate_interfaces(custom_msgs
       msg/TestFoxy.msg
     DEPENDENCIES
       builtin_interfaces
   )
   
   install(FILES mapping_rules.yaml
     DESTINATION share/${PROJECT_NAME}
   )
   
   ament_export_dependencies(rosidl_default_runtime)
   
   ament_package()
   

   package.xml如下：

   <?xml version="1.0"?>
   <?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
   <package format="3">
     <name>custom_msgs</name>
     <version>0.0.0</version>
     <description>The custom_msgs package</description>
   
     <maintainer email="weibw@todo.todo">weibw</maintainer>
   
     <license>TODO</license>
   
     <depend>rclpy</depend>
     <depend>builtin_interfaces</depend>
     <depend>rosidl_default_generators</depend>
   
     <member_of_group>rosidl_interface_packages</member_of_group>
   
     <export>
       <build_type>ament_cmake</build_type>
       <ros1_bridge mapping_rules="mapping_rules.yaml"/>
     </export>
   </package>
   

4. 编译ros2下的custom_msgs功能包

   source /opt/ros/foxy/setup.bash
   cd colcon_ws
   colcon build --packages-select custom_msgs
   

5. 下载ros1_bridge源码，由于我们要桥接自定义消息，所以ros1_bridge必须重新编译

   源码到github自行下载，放到colcon_ws工作空间中

   source /opt/ros/noetic/setup.bash
   source /opt/ros/foxy/setup.bash
   source catkin_ws/devel/setup.bash
   source colcon/install/setup.bash
   cd colcon_ws
   colcon build --packages-select ros1_bridge --cmake-force-configure
   

   编译完成后命令行输入:

   source colcon/install/setup.bash
   ros2 run ros1_bridge dynamic_bridge --print-pairs | grep custom_msgs
   

   如果显示：

   - 'custom_msgs/msg/TestFoxy' (ROS 2) <=> 'custom_msgs/TestNoetic' (ROS 1)
   

   则代表桥接数据转换成功

6. 编译通过后再创建一个测试用的ros2软件包bridge_test，编写一个简单的订阅器来监听话题，验证桥接是否成功

   ros2 pkg create --build-type ament_cmake bridge_test --dependencies custom_msgs
   

   创建test.cpp，内容如下

   #include <memory>
   
   #include "rclcpp/rclcpp.hpp"
   #include "custom_msgs/msg/test_foxy.hpp"
   using std::placeholders::_1;
   
   class MinimalSubscriber : public rclcpp::Node
   {
     public:
       MinimalSubscriber()
       : Node("minimal_subscriber")
       {
         subscription_ = this->create_subscription<custom_msgs::msg::TestFoxy>(
         "topic", 10, std::bind(&MinimalSubscriber::topic_callback, this, _1));
       }
   
     private:
       void topic_callback(const custom_msgs::msg::TestFoxy::SharedPtr msg) const
       {
         RCLCPP_INFO(this->get_logger(), "I heard custom_msgs::msg::TestFoxy : '%d'", msg->test_int);
       }
       rclcpp::Subscription<custom_msgs::msg::TestFoxy>::SharedPtr subscription_;
   };
   
   int main(int argc, char * argv[])
   {
     rclcpp::init(argc, argv);
     rclcpp::spin(std::make_shared<MinimalSubscriber>());
     rclcpp::shutdown();
     return 0;
   }
   

   CMakelists.txt如下

   cmake_minimum_required(VERSION 3.5)
   project(bridge_test)
   
   # Default to C99
   if(NOT CMAKE_C_STANDARD)
     set(CMAKE_C_STANDARD 99)
   endif()
   
   # Default to C++14
   if(NOT CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 14)
   endif()
   
   if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
     add_compile_options(-Wall -Wextra -Wpedantic)
   endif()
   
   # find dependencies
   find_package(ament_cmake REQUIRED)
   find_package(rclcpp REQUIRED)
   find_package(custom_msgs REQUIRED)
   
   add_executable(subscriber src/test.cpp)
   ament_target_dependencies(subscriber rclcpp custom_msgs)
   
   install(TARGETS
     subscriber
     DESTINATION lib/${PROJECT_NAME})
   
   ament_package()
   

   package.xml如下

   <?xml version="1.0"?>
   <?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
   <package format="3">
     <name>bridge_test</name>
     <version>0.0.0</version>
     <description>TODO: Package description</description>
     <maintainer email="weibw@todo.todo">weibw</maintainer>
     <license>TODO: License declaration</license>
   
     <buildtool_depend>ament_cmake</buildtool_depend>
     <depend>rclcpp</depend>
     <depend>custom_msgs</depend>
   
     <test_depend>ament_lint_auto</test_depend>
     <test_depend>ament_lint_common</test_depend>
   
     <export>
       <build_type>ament_cmake</build_type>
     </export>
   </package>
   

   编译功能包

   cd colcon_ws
   colcon build --packages-select bridge_test
   

7. 验证桥接自定义消息是否成功

   在ros1环境下使用命令行工具以固定频率向外广播话题数据

   source /opt/ros/noetic/setup.bash
   source catkin_ws/devel/setup.bash
   roscore&
   rostopic pub topic custom_msgs/TestNoetic "test_str1: 'hello'
   test_int: 234" -r 2
   

   在ros2环境下运行订阅节点

   source /opt/ros/foxy/setup.bash
   source colcon_ws/install/setup.bash
   ros2 run bridge_test subscriber
   

   运行ros1_bridge

   source /opt/ros/noetic/setup.bash
   source /opt/ros/foxy/setup.bash
   source catkin_ws/devel/setup.bash
   source colcon/install/setup.bash
   ros2 run ros1_bridge dynamic_bridge
   

   此时应该在ros2的订阅节点终端中看到如下打印：

   [INFO] [1645162912.958789169] [minimal_subscriber]: I heard custom_msgs::msg::TestFoxy : '234'
   

   至此，本文结束