dPackard's profile - activity

For example -

root@hekateros# rosnode info /hekateros_control
[...removed for brevity...]
Subscriptions:
  * /hekateros_control/follow_joint_traj_as/goal [unknown type]
[...removed for brevity...]

This message type _should_ be trajectory_msgs/JointTrajectory...

Note that this does not affect the execution of the code (i.e. I can still publish messages of the correct type to this topic, and it works correctly)

I would just like to know why rosnode info is unable to display the correct message type information. Do I need to specify a dependency somewhere? And if so, why does the missing dependency not affect message generation, compilation, or execution?

Thanks!

/daniel

When you say "on the arduino side, the publisher works well", could you be a bit more specific? (e.g. "values from the arduino are visible in the serial-monitor in the Arduino IDE", or "values from the arduino are published by a ROS node that reads values from the arduino via a serial conn", or ...)

Good luck! It sounds like you are on your way to figuring it out :D

Don't forget to source the setup.bash file for your catkin workspace in *every terminal* you are using.

If you are developing under ROS Groovy or newer, the idea of a "stack" has been replaced by the idea of a "metapackage". See Metapackages and the Elimination of Stacks

Metapackages are essentially "empty" packages that group related packages together through runtime dependencies (<run_depends>)

You will want to learn more about catkin (the preferred build system in groovy and newer): http://ros.org/wiki/catkin

In particular, here is some info about metapackages: http://ros.org/wiki/catkin/package.xml#Metapackages

And here is an example of a metapackage: https://github.com/roadnarrows-robotics/hekateros/tree/master/hekateros

If this didn't help, please update your question with more details describing your exact situation (e.g. how you registered the callback in your code, what is the output of `rostopic echo <topic name="">`, of `rosnode info <node name="">`, etc), and maybe someone can help you find an exact solution

If you've included a ROS_INFO statement in your callback, and that message doesn't show up in rosconsole or the terminal where you started the node, then your cb is not being executed.

There are a few possible reasons that your callback would not be executed... but I'm going to guess at a couple likely reasons since you don't run into any build errors. I'm guessing that this is a callback for a subscribed topic. The callback for a subscribed topic is only executed when new data is published to the topic you've subscribed to.

This suggests that A) no data is being published to the topic you are subscribed to, or B) you are subscribed to a topic that doesn't exist

The rostopic and rqt_graph tools can help you investigate these possibilities.

• http://www.ros.org/wiki/rostopic
• http://www.ros.org/wiki/rqt_graph
• http://www.ros.org/wiki/ROS/Tutorials/UnderstandingTopics

If that file already exists (or if creating it doesn't help), you might find a solution here: ( http://answers.ros.org/question/55201/using-ros-with-kinect-failed-to-set-usb-interface/ )

If you installed the package via apt-get, tit is probably installed already (just check if the file exists). Otherwise you can create the file manually using your favorite text editor and `sudo`. (e.g. `sudo gvim /etc/udev/rules.d/55-primesense-usb.rules`).

Did you install `/55-primesense-usb.rules` to /etc/udev/rules.d? This file may be found here: https://github.com/PrimeSense/Sensor/blob/unstable/Platform/Linux/Install/55-primesense-usb.rules )

To check if your function callback "*works*" is slightly different than checking if the function callback is "*being executed*" ;) - but yes, add ROS_INFO("Executing poseCallback"); as the very first line of your function. If that function is being executed, you will see it in the log messages.

You should learn some of the basics of linux/BASH before diving into the ROS tutorials (e.g. http://www.ee.surrey.ac.uk/Teaching/Unix/). There's quite a learning curve for Linux+ROS if you're completely new to it, but with your background you should be up and running soon!

I think this tutorial covers what you would like to do:

• http://www.ros.org/wiki/rospy_tutorials/Tutorials/Makefile#Installing_scripts_and_exporting_modules

summary:

1. Create setup.py in your package root directory with these contents (where <python_mod> is replaced by the name of your python module, typically the same name as your catkin package)

## ! DO NOT MANUALLY INVOKE THIS setup.py, USE CATKIN INSTEAD

from distutils.core import setup
from catkin_pkg.python_setup import generate_distutils_setup

# fetch values from package.xml
setup_args = generate_distutils_setup(
    packages=['<python_mod>'],
    package_dir={'': 'src'},
    requires=['std_msgs', 'rospy'])
)

setup(**setup_args)

2. Add the following line to your CMakeLists.txt

catkin_python_setup()

3. Create a directory for your python scripts (if you have any python executables)

mkdir <pkg_root>/scripts

4. Create a directory for your python modules

mkdir <pkg_root>/src/<python_mod>/

5. Add an empty __init__.py to your python module directory

touch <pkg_root>/src/<python_mod>/__init__.py

6. create your python mod

touch <pkg_root>/src/<python_mod>/mod1.py

You should now be able to import this module as

import python_mod.mod1

Hope that helps!

Reference the tutorial for details.

Since catkin_make succeeded, the environment is probably configured properly. But, as @lifelonglearner says, you must start `roscore` in a separate terminal before you can issue `rosrun beginner_tutorials add_two_ints_server.py`.

This is a fresh post regarding the question raised here.

Basically, I'd like to know if installing ROS package dependencies from a third-party apt repository is supported/recommended. I understand that non-debian users would still need to install these packages from source.

I see at least one third-party apt repository added in the rosdistro/rosdep/base.yaml, see lines 540-552

However, based on the discussion here , and REPS 111, 112 and 125 - I get the feeling that embedding bash commands and adding apt-repos in a rosdep.yaml is frowned upon.

What is the best way to add system dependencies from a third-party apt repository to a ROS package?

/daniel