If you're doing this you probably want to use getParamCached(), as
getParam() itself is expensive (it incurs an xmlrpc call to the master).
http://www.ros.org/wiki/roscpp/Overview/Parameter%20Server#Cached_Parameters

Blaise can answer in more detail, but dynamic_reconfigure allows things like
automatic GUI generation and feedback from the node (for e.g. invalid values
etc.).

Josh

On Mon, Apr 19, 2010 at 11:18 AM, 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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> > https://code.ros.org/mailman/listinfo/ros-users
> >
>
>
>
> --
> 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
>
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