[ros-users] SICK LMS Subscriber Node

[Rishi Bedi]

Hi Morgan,
Okay -- say I wanted to read in just the range values from sicklms -- how
can I just grab those? When I use rostopic echo /scan, the ranges show up as
a list within brackets - is there a way I can pick out data from a topic my
node is subscribing to? Sorry if I'm being a bit dense -- I'm not well
versed on handling data types in C++.
Best,
Rishi

Rishi Bedi
rbedi100 at gmail.com


On Thu, Jul 15, 2010 at 3:00 PM, Morgan Quigley <mquigley at cs.stanford.edu>wrote:

> Hi Rishi,
>
> Since there are such a wide variety of data types in the system that
> would need different useful string representations, the auto-generated
> message types don't create a string-generation function. You'll need
> to assemble a string yourself using stringstream or whatever.
>
> Cheers,
> Morgan
>
>
> On Thu, Jul 15, 2010 at 11:55 AM, Rishi Bedi <rbedi100 at gmail.com> wrote:
> > Hi,
> > I'm trying to write a node that subscribes to the "/scan" topic, which is
> > published by sicktoolbox_wrapper. I tried to modify some of the code
> given
> > in the "Writing a Simple Publisher/Subscriber" tutorial:
> >
> > #include <ros/ros.h>
> > #include <std_msgs/String.h>
> > #include <sensor_msgs/LaserScan.h>
> >
> > void scanCallback (const sensor_msgs::LaserScan::ConstPtr& scan_msg)
> >
> > {
> >   ROS_INFO("Received [%s]", scan_msg);
> > }
> >
> > int main(int argc, char** argv)
> > {
> >   ros::init(argc, argv, "listener");
> >   ros::NodeHandle n;
> >   ros::Subscriber scan_sub = n.subscribe("scan", 100, scanCallback);
> >   ros::spin();
> > }
> >
> > The part where I think I'm getting tripped up is line 8 (the ROS_INFO
> > command) -- how do I handle the unique data type LaserScan that
> > sicktoolbox_wrapper uses to publish the scan data? I want to print the
> range
> > values out, preferably as one long string -- what is the best way to
> convert
> > the LaserScan type data into a string (or array)?
> >
> > Thanks a lot --
> > Rishi
> >
> > Rishi Bedi
> > rbedi100 at gmail.com
> >
> > _______________________________________________
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> >
> >
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