1.(1)編寫一個C++話題發佈者
/**
* 該例程將發佈/person_info話題,自定義消息類型learning_topic::Person
*/
#include <ros/ros.h>
#include "learning_topic/Person.h"
int main(int argc, char **argv)
{
// ROS節點初始化
ros::init(argc, argv, "person_publisher");
// 創建節點句柄,用來管理節點資源
ros::NodeHandle n;
// 創建一個Publisher,發佈名爲/person_info的topic,消息類型爲learning_topic::Person,隊列長度10(即緩衝區,在沒來得及發佈出去之前的排隊,若超出隊列,會丟失較早的信息,可能導致掉幀)
ros::Publisher person_info_pub = n.advertise<learning_topic::Person>("/person_info", 10);
// 設置循環的頻率
ros::Rate loop_rate(1);
int count = 0;
while (ros::ok())
{
// 初始化learning_topic::Person類型的消息
learning_topic::Person person_msg;
person_msg.name = "Tom";
person_msg.age = 18;
person_msg.sex = learning_topic::Person::male;
// 發佈消息
person_info_pub.publish(person_msg);
ROS_INFO("Publish Person Info: name:%s age:%d sex:%d",
person_msg.name.c_str(), person_msg.age, person_msg.sex);
// 按照循環頻率延時
loop_rate.sleep();
}
return 0;
}
(2)編寫一個Python話題發佈者
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# 該例程將發佈turtle1/cmd_vel話題,消息類型geometry_msgs::Twist
import rospy
from geometry_msgs.msg import Twist
def velocity_publisher():
# ROS節點初始化
rospy.init_node('velocity_publisher', anonymous=True)
# 創建一個Publisher,發佈名爲/turtle1/cmd_vel的topic,消息類型爲geometry_msgs::Twist,隊列長度10
turtle_vel_pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
#設置循環的頻率
rate = rospy.Rate(10)
while not rospy.is_shutdown():
# 初始化geometry_msgs::Twist類型的消息
vel_msg = Twist()
vel_msg.linear.x = 0.5
vel_msg.angular.z = 0.2
# 發佈消息
turtle_vel_pub.publish(vel_msg)
rospy.loginfo("Publsh turtle velocity command[%0.2f m/s, %0.2f rad/s]",
vel_msg.linear.x, vel_msg.angular.z)
# 按照循環頻率延時
rate.sleep()
if __name__ == '__main__':
try:
velocity_publisher()
except rospy.ROSInterruptException:
pass
總結:
1.初始化ROS節點
2.向ROS Master註冊節點信息,包括話題名和話題中的消息類型
3.創建消息數據
4.按照一定循環頻率發佈消息
2.配置發佈者代碼編譯規則(c++)
打開包目錄下的CMakeLists.txt,將add_executable(velocity_publisher src/velocity_publisher.cpp)
target_link_libraries(velocity_publisher ${catkin_LIBRARIES})寫入如下位置。
3.編譯並運行發佈者