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

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geometry_msgs/PoseStamped.msg结构

# A Pose with reference coordinate frame and timestamp

Header header

Pose pose

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geometry_msgs/Pose.msg结构

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

Point position

Quaternion orientation

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geometry_msgs/Point.msg结构

# This contains the position of a point in free space

float64 x

float64 y

float64 z

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geometry_msgs/Quaternion.msg结构

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

float64 x

float64 y

float64 z

float64 w

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实现代码：

#include <ros/ros.h>

#include <ros/console.h>

#include <nav_msgs/Path.h>

#include <std_msgs/String.h>

#include <geometry_msgs/Quaternion.h>

#include <geometry_msgs/PoseStamped.h>

#include <tf/transform_broadcaster.h>

#include <tf/tf.h>

main (int argc, char **argv)

{

ros::init (argc, argv, "showpath");

ros::NodeHandle ph;

ros::Publisher path_pub = ph.advertise<nav_msgs::Path>("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;

}

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