alexjs's profile - activity

Thank yo so much, that was the problem!

Hi. This is probably an insignificant problem, but I just can't see it.

I used the publisher/subscriber tutorial to make communication in my own program. The publisher publish well in a topic, and the subscriber is subscribe to it, or 'rostopic info' says so, but the callback function does not even start. Whatever I have inside (a variable change, a ROS_INFO, etc.), nothing seems to happen.

This is my code (without the lines of my own program, which are not important):

Publisher:

#include <ros/ros.h>
#include "std_msgs/String.h"
#include <sstream>
#include <iostream>

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

  ros::NodeHandle nh;

  std_msgs::String msg;

  ros::Publisher chatter_pub = nh.advertise<std_msgs::String>("chatter", 10);


  ros::Rate rate(10.0);

  while (nh.ok()){

    msg.data = "hello world";
    chatter_pub.publish(msg);


    ros::spinOnce();

    rate.sleep();
  }
  return 0;
};

Subscriber:

#include <ros/ros.h>
#include <ros/console.h>
#include <std_msgs/String.h>
#include <iostream>
#include <sstream>

int message=0;

void cb(const std_msgs::String::ConstPtr& msg)
{
  ROS_INFO_STREAM("callback");
  message=1;

}


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

ros::NodeHandle n;

  ros::Rate rate(10.0);
  while (node.ok()){

 ros::Subscriber sub = n.subscribe ("/chatter", 10, cb);

 ROS_INFO_STREAM(message);
    rate.sleep();
  }

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

Everything else from the program works, and it executes well, it is just the callback function wich seems not to run.

Thanks in advance for the answers.

Hi, I’m working on body position recognition using Kinect and openni_tracker, specifically the origin points (x, y and z) of the transformations (head, torso, elbow, hand…) given by the tracker. I have the points and now I pretend to work with them to recognize some specific positions of the body previously memorized.

I was told that Mahalanobis distance should work fine with this variables but I want to know if there is some other way to do it, some algorithm or a program already done.

I’m using ROS Groovy, so the MIT package is not an option, since I couldn’t make it work.

Thanks in advance.