【ROS2快速学习】

ROS2

去中心化master
不重复造轮子，更换为DDS

工具：

1. 常用指令

功能	ROS1	ROS2
录制话题	rosbag record xxx	ros2 bag record xxx
播放话题	rosbag play xxx.bag	ros2 bag play xxx
查看数据包内容	Rosbag info xxx.bag	Ros2 bag info xxx.db3
查看话题列表	rostopic list	Ros2 topic list
查看话题列表， 增加消息类型		ros2 topic list -t
输出话题内容	Rostopic echo xxx	Ros2 topic echo xxx
查看某话题	rostopic info xxx	ros2 topic info xxx
查看msg 内容	rosmsg show xxx	ros2 interface show xxx
话题发布	rostopic pub xxx	ros2 topic pub xxx

2. 数据包转换

# 安装 工具
pip3 install rosbags
# 更新
pip3 install --upgrade rosbags
# 下载慢，指定下载源 
pip3 install rosbags -i https://pypi.tuna.tsinghua.edu.cn/simple
# 使用方法  目标文件夹路径: 转换后的数据包存放的文件夹和转换后数据包的名称
rosbags-convert <源文件路径> --dst <目标文件夹路径>
# ros2 -> ros1 
rosbags-convert <your-ros2-bag>
# ros1 -> ros2 
rosbags-convert <your-ros1-bag>

3. 具体区别

消息订阅

ROS1

void chatterCallback(const std_msgs::String::ConstPtr& msg) {
    ROS_INFO("ROS 1 Heard: [%s]", msg->data.c_str());
}
int main(int argc, char** argv) {
    ros::init(argc, argv, "ros1_subscriber");
    ros::NodeHandle nh;
    // 创建订阅者
    ros::Subscriber sub = nh.subscribe("chatter", 10, chatterCallback);
    ROS_INFO("ROS 1 Subscriber ready...");
    // 进入循环处理回调
    ros::spin();
    return 0;
}

ROS2

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

using std::placeholders::_1;

class ROS2Subscriber : public rclcpp::Node {
public:
    ROS2Subscriber() : Node("ros2_subscriber") {
        // 创建订阅者 (使用lambda表达式或bind)
        subscription_ = this->create_subscription<std_msgs::msg::String>(
            "chatter", 10, std::bind(&ROS2Subscriber::topic_callback, this, _1));
            
        RCLCPP_INFO(this->get_logger(), "ROS 2 Subscriber ready...");
    }

private:
    void topic_callback(const std_msgs::msg::String::SharedPtr msg) const {
        RCLCPP_INFO(this->get_logger(), "ROS 2 Heard: '%s'", msg->data.c_str());
    }
    
    rclcpp::Subscription<std_msgs::msg::String>::SharedPtr subscription_;
};

int main(int argc, char* argv[]) {
    rclcpp::init(argc, argv);
    auto node = std::make_shared<ROS2Subscriber>();
    rclcpp::spin(node);
    rclcpp::shutdown();
    return 0;
}

消息发布

ROS1

	// 初始化ROS节点
    ros::init(argc, argv, "ros1_publisher");
    ros::NodeHandle nh;
    
    // 创建发布者
    ros::Publisher pub = nh.advertise<std_msgs::String>("chatter", 10);
    
    ros::Rate rate(1); // 1Hz
    int count = 0;
    
    while (ros::ok()) {
        std_msgs::String msg;
        msg.data = "Hello ROS 1: " + std::to_string(count++);
        // 发布消息
        pub.publish(msg);
  
        ROS_INFO("Published: %s", msg.data.c_str());
        rate.sleep();
    }

ROS2

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

using namespace std::chrono_literals;

class ROS2Publisher : public rclcpp::Node {
public:
    ROS2Publisher() : Node("ros2_publisher"), count_(0) {
        // 创建发布者 (使用泛型模板)
        publisher_ = this->create_publisher<std_msgs::msg::String>("chatter", 10);
        
        // 创建定时器
        timer_ = this->create_wall_timer(
            1000ms, std::bind(&ROS2Publisher::timer_callback, this));
    }

private:
    void timer_callback() {
        auto message = std_msgs::msg::String();
        message.data = "Hello ROS 2: " + std::to_string(count_++);
        
        // 发布消息
        publisher_->publish(message);
        
        RCLCPP_INFO(this->get_logger(), "Published: '%s'", message.data.c_str());
    }
    
    rclcpp::TimerBase::SharedPtr timer_;
    rclcpp::Publisher<std_msgs::msg::String>::SharedPtr publisher_;
    size_t count_;
};

int main(int argc, char* argv[]) {
    // 初始化ROS 2
    rclcpp::init(argc, argv);
    
    // 创建并运行节点
    auto node = std::make_shared<ROS2Publisher>();
    rclcpp::spin(node);
    
    // 关闭ROS 2
    rclcpp::shutdown();
    return 0;
}

消息区别

ROS1

# std_msgs/String.msg
# #include "std_msgs/String.h"
string data

ROS2

# std_msgs/msg/String.msg
#include "std_msgs/msg/string.hpp"
# ROS 2 消息在 msg 子命名空间中
string data

自定义消息

ROS1

# my_package/msg/MyCustom.msg

string first_name
string last_name
uint32 age
float32 score

package.xml

<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>

CMakeLists.txt

find_package(catkin REQUIRED COMPONENTS
  message_generation
  std_msgs
)

add_message_files(
  FILES
  MyCustom.msg
)

generate_messages(
  DEPENDENCIES
  std_msgs
)

catkin_package(
  CATKIN_DEPENDS message_runtime std_msgs
)

ROS2

string first_name
string last_name
uint32 age
float32 score

package.xml

<buildtool_depend>ament_cmake</buildtool_depend>
<depend>rosidl_default_generators</depend>
<exec_depend>rosidl_default_runtime</exec_depend>
<member_of_group>rosidl_interface_packages</member_of_group>

CMakeLists.txt

find_package(ament_cmake REQUIRED)
find_package(rosidl_default_generators REQUIRED)

rosidl_generate_interfaces(${PROJECT_NAME}
  "msg/MyCustom.msg"
  DEPENDENCIES std_msgs
)

ament_export_dependencies(rosidl_default_runtime)

主要架构差别

特性	ROS 1	ROS 2
节点初始化	ros::init()	rclcpp::init()
节点创建	ros::NodeHandle	继承 rclcpp::Node
发布者	nh.advertise<>()	create_publisher<>()
订阅者	nh.subscribe()	create_subscription<>()
消息类型	std_msgs::String	std_msgs::msg::String
回调处理	ros::spin()	rclcpp::spin()
消息指针	ConstPtr	SharedPtr
命名空间	扁平结构	msg 子命名空间
构建系统	catkin	ament_cmake
消息生成	message_generation	rosidl_default_generators

4. ROS2 调试

# 错误
error while loading shared libraries: libOgreMain.so.1.12.1: cannot open shared object file: No such file or directory

# 解决
source /opt/ros/humble/setup.bash 

# 错误
root@nuc:/workspace# ros2 run rviz2 rviz2 
qt.qpa.xcb: could not connect to display 
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, xcb.
[ros2run]: Aborted
# 解决

ROS2 Docker 可视化

https://blog.youkuaiyun.com/qq_39779233/article/details/142900876
# 这个写到brshrc 中
export DISPLAY=:0
# 在docker 环境外执行
xhost +local:

ROS2多机

• 物理连接性测试 组播测试

  # 发送端
  ros2 multicast send
  
  # 接收端
  ros2 multicast receive
  

• 通讯测试

  sudo apt install ros-humble-examples-rclpy-minimal-publisher
  # 发送端
  ros2 run examples_rclcpp_minimal_publisher publisher_member_function
  # 接收端
  ros2 topic list
  

• 设置ROS_DOMAIN_ID

  # 设置 domain_id 
  export ROS_DOMAIN_ID=1
  # 打印 domain_id 
  echo $ROS_DOMAIN_ID
  

  • ROS_DOMAIN_ID 相同，即可相互通信
  • ROS_DOMAIN_ID 不同，不可相互通信，但是组播测试成功