2.2. Ros+px4 simulation multi-point cruise flight - Square

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introduction ： This section is performed after the simulation environment has been installed . The installation of simulation environment can refer to the video explanation ： Links are as follows

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After this part of the code starts , Drones will be deployed every interval 5 Fly a target point in seconds , Total flight 4 A little bit , Form a square

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ROS Explanation of UAV multi-point flight

The video starts with the little turtle routine , The topic subscription and publication are described in detail , The code in this section is analyzed later
video ： Code details

1、 Enter into Firmware Under the folder , start-up gazebo Simulation environment ：

 make px4_sitl_default gazebo

2、 start-up MAVROS Simulation

roslaunch mavros px4.launch fcu_url:="udp://:[email protected]:14557"

3、 Start flying square node

rosrun square_demo square_demo_node

#include <ros/ros.h>
#include <geometry_msgs/PoseStamped.h>
#include <mavros_msgs/CommandBool.h>
#include <mavros_msgs/SetMode.h>
#include <mavros_msgs/State.h>

int count;
int flag=1;
mavros_msgs::State current_state;
void state_cb(const mavros_msgs::State::ConstPtr& msg){
    
    current_state = *msg;
}

int main(int argc, char **argv)
{
    
    ros::init(argc, argv, "offboard");
    ros::NodeHandle nh;

    ros::Subscriber state_sub = nh.subscribe<mavros_msgs::State>
            ("mavros/state", 10, state_cb);
    ros::Publisher local_pos_pub = nh.advertise<geometry_msgs::PoseStamped>
            ("mavros/setpoint_position/local", 10);
    ros::ServiceClient arming_client = nh.serviceClient<mavros_msgs::CommandBool>
            ("mavros/cmd/arming");
    ros::ServiceClient set_mode_client = nh.serviceClient<mavros_msgs::SetMode>
            ("mavros/set_mode");

    //the setpoint publishing rate MUST be faster than 2Hz
    ros::Rate rate(8.0);

    // wait for FCU connection
    while(ros::ok() && !current_state.connected){
    
        ros::spinOnce();
        rate.sleep();
    }
    geometry_msgs::PoseStamped pose;
    pose.pose.position.x = 0;
    pose.pose.position.y = 0;
    pose.pose.position.z = 3;
   
    //send a few setpoints before starting
    for(int i = 100; ros::ok() && i > 0; --i){
    
        local_pos_pub.publish(pose);
        ros::spinOnce();
        rate.sleep();
    }

    mavros_msgs::SetMode offb_set_mode;
    offb_set_mode.request.custom_mode = "OFFBOARD";

    mavros_msgs::CommandBool arm_cmd;
    arm_cmd.request.value = true;

    ros::Time last_request = ros::Time::now();
    
    while(ros::ok())
   {
    
		
	if( current_state.mode != "OFFBOARD" &&
            (ros::Time::now() - last_request > ros::Duration(5.0))){
    
            if( set_mode_client.call(offb_set_mode) &&
                offb_set_mode.response.mode_sent){
    
                ROS_INFO("Offboard enabled");
            }
            last_request = ros::Time::now();
        } else {
    
            if( !current_state.armed &&
                (ros::Time::now() - last_request > ros::Duration(5.0))){
    
                if( arming_client.call(arm_cmd) &&
                    arm_cmd.response.success){
    
                    ROS_INFO("Vehicle armed");
                }
                last_request = ros::Time::now();
            }
        }
		
            if((flag == 1)  && (ros::Time::now() - last_request > ros::Duration(5.0)))
		{
     
			ROS_INFO("position1(0 , 0, 5)");
                	pose.pose.position.x = 0;
    			pose.pose.position.y = 0;
    			pose.pose.position.z = 5;
			last_request = ros::Time::now();
                        flag=2;
			//local_pos_pub.publish(pose);

                }

		if((flag ==2) && (ros::Time::now() - last_request > ros::Duration(5.0)))
		{
    
			ROS_INFO("position2(5 , 0, 5)");
                	pose.pose.position.x = 5.0;
    			pose.pose.position.y = 0.0;
    			pose.pose.position.z = 5;
			last_request = ros::Time::now();
			flag=3;
			//local_pos_pub.publish(pose);
                }
                       
		 if((flag ==3) && (ros::Time::now() - last_request > ros::Duration(5.0)))
                {
    
                        ROS_INFO("position3(5 , 5, 5)");
                        pose.pose.position.x = 5.0;
                        pose.pose.position.y = 5.0;
                        pose.pose.position.z = 5;
                        last_request = ros::Time::now();
			flag=4;
                        //local_pos_pub.publish(pose);
                }

		 if((flag ==4) && (ros::Time::now() - last_request > ros::Duration(5.0)))
                {
    
                        ROS_INFO("position4(0 , 5, 5)");
                        pose.pose.position.x = 0;
                        pose.pose.position.y = 5.0;
                        pose.pose.position.z = 5;
                        last_request = ros::Time::now();
			flag=5;
                        //local_pos_pub.publish(pose);
                }


		 if((flag ==5) && (ros::Time::now() - last_request > ros::Duration(5.0)))
                {
    
                        ROS_INFO("position5(0 ,0, 5)");
                        pose.pose.position.x = 0;
                        pose.pose.position.y = 0;
                        pose.pose.position.z = 5;
                        last_request = ros::Time::now();
			flag=6;
                        //local_pos_pub.publish(pose);
                }
        local_pos_pub.publish(pose);
        ros::spinOnce();
        rate.sleep();
    }

    return 0;
}