tf入门

• 推荐一个雷锋精神的资源http://v.youku.com/v_show/id_XMTY2NDI4MzQ5Ng==.html?spm=a2h0j.8191423.playlist_content.5!2~5~5~A&&f=27718645&from=y1.2-3.4.2
• ros tf tutorial 网址http://wiki.ros.org/tf/Tutorials/Writing%20a%20tf%20broadcaster%20%28C%2B%2B%29

• tf 工具

  • rosrun tf view_frames 在当前目录中生产一个frames.pdf，evince命令查看
  • rosrun rqt_tf_tree rqt_tf_tree 运行可视化图形工具。
  • rosrun tf tf_echo [reference_frame] [target_frame] 屏幕打印两个坐标系的变化，Translation 和 Rotation.
  • rosrun rviz rviz -d rospack find turtle_tf/rviz/turtle_rviz.rviz 可视化图形化显示坐标系之间的变化 x-red;y-green;z-blue;

• 例程1

  • 广播小乌龟的位姿到tf包。

#include <ros/ros.h>
#include <tf/transform_broadcaster.h>
#include <turtlesim/Pose.h>

std::string turtle_name;



void poseCallback(const turtlesim::PoseConstPtr& msg){
  static tf::TransformBroadcaster br;
  tf::Transform transform;
  transform.setOrigin( tf::Vector3(msg->x, msg->y, 0.0) );
  tf::Quaternion q;
  q.setRPY(0, 0, msg->theta);
  transform.setRotation(q);
  br.sendTransform(tf::StampedTransform(transform, ros::Time::now(), "world", turtle_name));
}

int main(int argc, char** argv){
  ros::init(argc, argv, "my_tf_broadcaster");
  if (argc != 2){ROS_ERROR("need turtle name as argument"); return -1;};
  turtle_name = argv[1];

  ros::NodeHandle node;
  ros::Subscriber sub = node.subscribe(turtle_name+"/pose", 10, &poseCallback);

  ros::spin();
  return 0;
};

br.sendTransform(tf::StampedTransform(transform, ros::Time::now(), “world”, turtle_name));
This is where the real work is done. Sending a transform with a TransformBroadcaster requires four arguments.

 - 第一个参数：定义的变换
 - 第二个参数：给变换一个时间戳，ros::Time::now().
 - 第三个参数：父框架，本例中为“world”
 - 第四个参数：子框架，本例中为turtle