Hi, the code i use is referring to the tf tutorial http://wiki.ros.org/tf/Tutorials/Writing%20a%20tf%20listener%20(C%2B%2B).

It works well in the simulator (arbotix), however, when i am using the real turtlebot (kobuki), it doesn't perform smoothly, often lose the target, any idea what is my problem?

this is my opennitracker launch file. i used `statictransformpublisherto introduce new tf which having same position with/skeletal/torso1and same orientation with/cameradepthframe`. this imitate the relationship between turtle1(/torso) and turtle2(/cameradepthframe) in the tutorial.

<launch>
  <node pkg="openni_tracker" name="openni_tracker" type="openni_tracker" output="screen">
    <param name="tf_prefix" value="skeleton" />
  </node>

  <node pkg="tf" type="static_transform_publisher" name="kinect_to_skeletal" args="0 0 0 0 0 0 /camera_depth_frame /skeleton/openni_depth_frame 100" />
  <node pkg="tf" type="static_transform_publisher" name="skeletal_to_target" args="0 0 0 -1.57 -1.57 0 /skeleton/torso_1 /target 100" />      
</launch>

this is my follower code:

#include "ros/ros.h"
#include <geometry_msgs/Twist.h>

#include <tf/transform_broadcaster.h>
#include <tf/transform_listener.h>


ros::Publisher cmdpub_;

tf::TransformBroadcaster *br;
tf::Transform *tftransform;
tf::TransformListener *ten;


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

  ros::NodeHandle nh;

  br = new tf::TransformBroadcaster();
  tftransform = new tf::Transform();
  ten = new tf::TransformListener();

  cmdpub_ = nh.advertise<geometry_msgs::Twist> ("cmd_vel", 1); //cmd_vel_mux/input/navi

  //markersub_= nh.subscribe("ar_pose_marker", 1, &Listener::markercb, &marker);

        while (ros::ok())
      {

        geometry_msgs::TwistPtr cmd(new geometry_msgs::Twist());

        tf::StampedTransform transform;

        try {
          ten->waitForTransform("/camera_depth_frame", "/target", ros::Time(0), ros::Duration(10.0) );
          ten->lookupTransform("/camera_depth_frame", "/target", ros::Time(0), transform);
        } 
        catch (tf::TransformException ex) {
          ROS_ERROR("%s",ex.what());
        }        

        cmd->angular.z = 4 * atan2(transform.getOrigin().y(), transform.getOrigin().x()); //<1
        //cmd->linear.x = 0.01 * sqrt(pow(transform.getOrigin().x(), 2) + pow(transform.getOrigin().y(), 2)); //<1.5

        //ROS_INFO("I see transform x, y: %f %f", transform.getOrigin().x(), transform.getOrigin().y());

        if (std::abs(cmd->linear.x) < 1.5 && std::abs(cmd->angular.z) < 1){
          if (std::abs(cmd->angular.z) > 0.2){
            cmd->linear.x = 0.01 * sqrt(pow(transform.getOrigin().x(), 2) + pow(transform.getOrigin().y(), 2));
            cmdpub_.publish(cmd);     
          }
          else{
            cmd->linear.x = 0.1 * sqrt(pow(transform.getOrigin().x(), 2) + pow(transform.getOrigin().y(), 2));
            cmdpub_.publish(cmd);
          }
          ROS_INFO("I see cmd x, z: %f %f", cmd->linear.x, cmd->angular.z);
        }
      }  

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

please help. btw, is there any similar succeeded code i can refer to?