ROS在rviz中实时显示轨迹（nav_msgs/Path消息的使用）

本文分析nav_msgs/Path结构，实现在rviz中画出圆形轨迹。

消息结构说明

nav_msgs/Path.msg结构

#An array of poses that represents a Path for a robot to follow
Header header
geometry_msgs/PoseStamped[] poses

geometry_msgs/PoseStamped.msg结构

# A Pose with reference coordinate frame and timestamp
Header header
Pose pose

geometry_msgs/Pose.msg结构

# A representation of pose in free space, composed of position and orientation. 
Point position
Quaternion orientation

geometry_msgs/Point.msg结构

# This contains the position of a point in free space
float64 x
float64 y
float64 z

geometry_msgs/Quaternion.msg结构

# This represents an orientation in free space in quaternion form.

float64 x
float64 y
float64 z
float64 w

实现代码：

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

main (int argc, char **argv)
{
    ros::init (argc, argv, "showpath");

    ros::NodeHandle ph;
    ros::Publisher path_pub = ph.advertise("trajectory",1, true);

    ros::Time current_time, last_time;
    current_time = ros::Time::now();
    last_time = ros::Time::now();

    nav_msgs::Path path;
    //nav_msgs::Path path;
    path.header.stamp=current_time;
    path.header.frame_id="odom";


    double x = 0.0;
    double y = 0.0;
    double th = 0.0;
    double vx = 0.1;
    double vy = -0.1;
    double vth = 0.1;

    ros::Rate loop_rate(1);
    while (ros::ok())
    {

        current_time = ros::Time::now();
        //compute odometry in a typical way given the velocities of the robot
        double dt = (current_time - last_time).toSec();
        double delta_x = (vx * cos(th) - vy * sin(th)) * dt;
        double delta_y = (vx * sin(th) + vy * cos(th)) * dt;
        double delta_th = vth * dt;

        x += delta_x;
        y += delta_y;
        th += delta_th;


        geometry_msgs::PoseStamped this_pose_stamped;
        this_pose_stamped.pose.position.x = x;
        this_pose_stamped.pose.position.y = y;

        geometry_msgs::Quaternion goal_quat = tf::createQuaternionMsgFromYaw(th);
        this_pose_stamped.pose.orientation.x = goal_quat.x;
        this_pose_stamped.pose.orientation.y = goal_quat.y;
        this_pose_stamped.pose.orientation.z = goal_quat.z;
        this_pose_stamped.pose.orientation.w = goal_quat.w;

        this_pose_stamped.header.stamp=current_time;
        this_pose_stamped.header.frame_id="odom";
        path.poses.push_back(this_pose_stamped);

        path_pub.publish(path);
        ros::spinOnce();               // check for incoming messages

        last_time = current_time;
        loop_rate.sleep();
    }

    return 0;
}

rviz实验结果