Re: [ros-users] Best way to set the parameters for the contr…

Ugo,

as our guru Lorenz just pointed out, please note that the earlier
attached code was actually taking 100% of CPU.
I am attaching an improved version with added sleep in the spin function.
D.

On Mon, Apr 19, 2010 at 8:18 PM, Dejan Pangercic
<dejan.pangercic@gmail.com> wrote:
> Hi Ugo,
>
> I am by no means authority but this is the way I update parameters in my nodes:
> Define node's member function, e.g.:
> /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
>  double param_;
>  void
>      updateParametersFromServer ()
>    {
>      nh_.getParam ("my_param", param_);
>    }
> and then constantly call it in that node's spin function:
>
>      updateParametersFromServer ();
>
> See also an attached example file.
>
> Furthermore, I just recently stumbled upon
> http://www.ros.org/wiki/dynamic_reconfigure which "facilitates dynamic
> node reconfiguration". However I do not really understand in how far
> is it different to conventional updating of parameters as discussed
> before. But maybe Blaise can tell here more.
>
> D.
> On Mon, Apr 19, 2010 at 6:56 PM, Ugo Cupcic <ugo@shadowrobot.com> wrote:
>> Hi,
>>
>> I'm currently setting the parameters for the controllers (PID and so on)
>> via a message (I have a subscriber which updates the values when it
>> receives the corresponding message).
>>
>> It works well, but I wanted to know what was the recommended way of
>> doing that in ROS. Is it better to do it using parameters? (But then how
>> can I  change the corresponding values when the parameters are updated?)
>>
>> Cheers,
>>
>> Ugo
>>
>> --
>> Ugo Cupcic         |  Shadow Robot Company | ugo@shadowrobot.com
>> Software Engineer      251 Liverpool Road
>> need a Hand?           London  N1 1LX       | +44 20 7700 2487
>> http://www.shadowrobot.com/hand/              @shadowrobot
>>
>>
>> _______________________________________________
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>>
>
>
>
> --
> MSc. Dejan Pangercic
> PhD Student/Researcher
> Computer Science IX
> Technische Universität München
> Telephone: +49 (89) 289-17780
> E-Mail: dejan.pangercic@in.tum.de
> WWW: http://ias.cs.tum.edu/people/pangercic
>



--
MSc. Dejan Pangercic
PhD Student/Researcher
Computer Science IX
Technische Universität München
Telephone: +49 (89) 289-17780
E-Mail: dejan.pangercic@in.tum.de
WWW: http://ias.cs.tum.edu/people/pangercic
// #include <unistd.h>

#include <ctime>
#include <ros/node_handle.h>
#include <ros/ros.h>
#include <sensor_msgs/PointCloud.h>
#include <point_cloud_mapping/cloud_io.h>
#include <boost/thread/mutex.hpp>
#include <boost/format.hpp>

class MsgToPCD
{
  protected:
    ros::NodeHandle nh_;
    //dir_ - destination folder for pcds
    std::string input_cloud_topic_, dir_;
    ros::Subscriber cloud_sub_;
    int counter_;
    //for continous saving of pcds
    bool continous_; 
    bool debug_;
    //lock while saving to pcd
    boost::mutex m_lock_;
    boost::format filename_format_;

  public:
  MsgToPCD () :  nh_("~"), counter_(0), debug_(true)
    {
      nh_.param ("input_cloud_topic", input_cloud_topic_, std::string("cloud_pcd"));
      nh_.param ("dir", dir_, std::string(""));       
      nh_.param ("continous", continous_, false);   
      if(debug_)
      ROS_INFO("input_cloud_topic_: %s", input_cloud_topic_.c_str());
      cloud_sub_ = nh_.subscribe (input_cloud_topic_, 1, &MsgToPCD::cloud_cb, this);
    }

    void
      cloud_cb (const sensor_msgs::PointCloudConstPtr& cloud)
    {
      //std::ostringstream filename;
      //filename << dir_ << "cloud_" << time (NULL) << "_" << getpid () << ".pcd";
      //filename << dir_ << "cloud_" <<  << ".pcd";
      filename_format_.parse(std::string("cloud_%f.pcd"));
      std::string filename = dir_ + (filename_format_ %  ros::Time::now().toSec()).str();
      if(debug_)
      ROS_INFO("parameter continous: %d", continous_);
      if ((counter_ == 0) && (!continous_))
      {
        ROS_INFO ("PointCloud message received on %s with %d points. Saving to %s", input_cloud_topic_.c_str (), (int)cloud->points.size (), filename.c_str ());
        cloud_io::savePCDFile (filename.c_str (), *cloud, true);
      }
      if ((counter_ >= 0) && (continous_))
      {
        ROS_INFO ("PointCloud message received on %s with %d points. Saving to %s", input_cloud_topic_.c_str (), (int)cloud->points.size (), filename.c_str ());
        m_lock_.lock ();
        cloud_io::savePCDFile (filename.c_str (), *cloud, true);
        m_lock_.unlock ();
      }
      counter_ ++;
    }

/**
* @brief toggles parameter to start/stop saving pcds
*/

   void updateParametersFromServer ()
    {
      nh_.getParam ("continous", continous_);
      if(debug_)
      ROS_INFO("cont in update: %d", continous_);
    }

    bool 
      spin ()
    {
      ros::Rate loop_rate(1);
      while (nh_.ok())
      {
        ros::spinOnce ();
        if ((counter_ == 1) && (!continous_))
          return true;
        updateParametersFromServer();
    loop_rate.sleep();
      }
      return true;
    }
};

int main (int argc, char* argv[])
{
ros::init (argc, argv, "msg_to_pcd");

MsgToPCD n;
n.spin ();

return (0);
}