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Subscribing to topic throw compilation error

asked 2012-06-10 23:52:43 -0600

Erwan R. gravatar image

Hi ROS users !

I'm trying to write a simple controller that takes LaserScan and directly send motor command (in Braitenberg's style), but I'm quite struggling with subscription to node. The subscription method is not recognized when rosmaking and I don't understand what's wrong as I think I doing that the same way as in Writing a Publisher and Subscriber or Publishers and Subscribers.

Any hint would be welcome !

Here is the code :


Class definition

 #ifndef BRAITENBERG_CONTROLLER_H
 #define BRAITENBERG_CONTROLLER_H

 #include <iostream>
 #include <ros/ros.h>

 #include <geometry_msgs/Twist.h>

 #include <tf/transform_listener.h>
 #include <tf/message_filter.h>
 #include <message_filters/subscriber.h>

 #include <laser_geometry/laser_geometry.h>
 #include <sensor_msgs/LaserScan.h>

 namespace braitcontrol {

  class BrController
  {
     private :
        //! The node handle we'll be using
        ros::NodeHandle nh_;
        //! publishing to "/base_controller/command" topic
        ros::Publisher cmd_vel_pub_;
        ros::Subscriber scan_filter_sub_;

         //message_filters::Subscriber<sensor_msgs::LaserScan> scan_filter_sub_;

        tf::MessageFilter<sensor_msgs::LaserScan> * tf_filter_; 
        tf::TransformListener tf_;

        std::string target_frame_;

     public :
        BrController(ros::NodeHandle &nh);

        bool driveBraitenberg();
        sensor_msgs::LaserScan>& laser_ptr);
        void msgCallback(const sensor_msgs::LaserScan & msg);

    };

}

#endif

Class Implementation

#include "braitenberg_controller.h"

using namespace braitcontrol;

BrController::BrController(ros::NodeHandle &nh) : target_frame_("/base_controller/command")
{
   /* Node handle that manage the node and provide publishing and subscribing function */
   nh_ = nh;

   /* Set up the publisher for the cmd_vel topic : we'll publish on this topic to drive the robot */
   cmd_vel_pub_ = nh_.advertise<geometry_msgs::Twist>("/base_controller/command", 1);

   /* Same for subscriber */
   scan_filter_sub_ = nh_.subscribe("scan", 50, msgCallback); // Faulty line !!!
   //tf_filter_ = new tf::MessageFilter<sensor_msgs::LaserScan>(scan_filter_sub_, tf_, target_frame_, 10);    
}

 void BrController::msgCallback(const sensor_msgs::LaserScan & msg)
 {
    std::cout << "Callback" << std::endl;
 }

 bool BrController::driveBraitenberg()
 {
    // Just driving robot according a constant rotation command
    //we are sending commands of type "twist" to drive the robot
    geometry_msgs::Twist base_cmd;


float cmd = 50.0;

    while(nh_.ok())
    {       
     base_cmd.angular.z = cmd;
         //publish the assembled command
         cmd_vel_pub_.publish(base_cmd);
    }

  return true;
}

int main(int argc, char** argv)
{
  //init the ROS node
  ros::init(argc, argv, "braitenberg_controller");
  ros::NodeHandle nh;

  BrController bControl(nh);
  bControl.driveBraitenberg();

  return 0;
}

And here is the error :

  [100%] Building CXX object CMakeFiles/pr2_braitenberg_controller.dir/src/braitenberg_controller.o
/home/renaudo/ros_workspace/pr2_braitenberg_controller/src/braitenberg_controller.cpp:
    In constructor ‘braitcontrol::BrController::BrController(ros::NodeHandle&)’:
/home/renaudo/ros_workspace/pr2_braitenberg_controller/src/braitenberg_controller.cpp:13: error:
    no matching function for call to ‘ros::NodeHandle::subscribe(const char [5], int, <unresolved overloaded function type>)’
/opt/ros/electric/stacks/ros_comm/clients/cpp/roscpp/include/ros/node_handle.h:785: note:
    candidates are: ros::Subscriber   ros::NodeHandle::subscribe(ros::SubscribeOptions&)
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1 Answer

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6

answered 2012-06-11 00:13:27 -0600

karthik gravatar image

updated 2012-06-11 01:04:06 -0600

Hi, Change the following

scan_filter_sub_ = nh_.subscribe("scan", 50, msgCallback);

to

scan_filter_sub_ = nh_.subscribe("scan", 50, &BrController::msgCallback, this);

And you have to remove ')' in the .h file at line num 38.

Hope it resolves the issue.

Thanks, Karthik

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Comments

1

Thanks for answering ! I tried that but error is the same except that the third argument is not "unresolved overloaded function type" but "void (braitcontrol::BrController::)(const sensor_msgs::LaserScan&)"*. It is still asking for SubscriberOptions but ...

Erwan R. gravatar imageErwan R. ( 2012-06-11 00:25:03 -0600 )edit

... I saw examples without using this structure (and that are supposed to work even if I didn't run them). At least, this (giving the right pointer) is correcting another issue.

Erwan R. gravatar imageErwan R. ( 2012-06-11 00:25:34 -0600 )edit

I just updated my answer with "this". Try n let me know

karthik gravatar imagekarthik ( 2012-06-11 00:55:42 -0600 )edit

It's now compiling but it seems that it's never receiving messages (even when remaped on /base_scan or /base_scan_throttled ). Laser are enabled with launching gmapping and checked with rViz. According to th Terminal output, only driveBraitenberg is executed and never the callback.

Erwan R. gravatar imageErwan R. ( 2012-06-11 03:06:19 -0600 )edit

Could you post this issue as a new question so that people will respond to it.

karthik gravatar imagekarthik ( 2012-06-11 05:08:13 -0600 )edit

Hi Erwan. i'm having exactly your last problem: my callback is never executed. how did you solved the issue?

rouch gravatar imagerouch ( 2014-04-16 05:08:23 -0600 )edit

Hello Rouch. I don't really remember what was the exact problem and the solution. From reading the code again, I guess it may be the lack of "ros::SpinOnce()" in the driveBraitenberg function. If that doesn't solve your problem, open a new question with details, I'll give it a try.

Erwan R. gravatar imageErwan R. ( 2014-04-16 11:58:04 -0600 )edit

No, was exactly that the problem, i wasn't spinning the callback queue. Shame on me :) thank you for the answer!

rouch gravatar imagerouch ( 2014-04-20 02:55:39 -0600 )edit

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Asked: 2012-06-10 23:52:43 -0600

Seen: 2,968 times

Last updated: Jun 11 '12