Setting up ROS and running the beginner tutorials on Ubuntu 16.04

This is the first in what I hope will be a series of posts, where I describe the installation procedures of software – stating the issues I faced and how I solved them.

Why? Because Linux….and literally every other piece of open source software aimed at the scientific/engineering community. You can only reinstall them a few times before you realize you should actually write down how you circumvented those same old bugs.

So first ROS.

Note: I believe most of these errors could have been avoided had I simply commented out Anaconda’s path in ~/.bashrc before beginning the installation

In installing ROS (Kinetic) on Ubuntu 16.04, I followed the instructions here for the Full desktop install. It was flawless.

After following the installation procedure stated at

http://wiki.ros.org/ROS/Tutorials/InstallingandConfiguringROSEnvironment

I proceeded to run

$ catkin_make

only to get the error

ImportError: "from catkin_pkg.package import parse_package" failed: No module named 'catkin_pkg'
Make sure that you have installed "catkin_pkg", it is up to date and on the PYTHONPATH.
CMake Error at /opt/ros/kinetic/share/catkin/cmake/safe_execute_process.cmake:11 (message):

So I checked the python path…

$ echo $PYTHONPATH
/opt/ros/kinetic/lib/python2.7/dist-packages

but knowing I had Anaconda with Python 3.5 installed, I checked to confirm which version was available

$ python
Python 3.5.2 |Anaconda custom (64-bit)

This implied installing catkin_pkg via apt-get would fail as it would be installed into Anaconda.

However, by using pip, I could install it into ROS’s python installation.

pip install catkin_pkg

With that cleared, catkin_make could run normally.

---

Continuing to the next tutorial, I tried to run rospack find, but got this

$ rospack find roscpp
$ [rospack] Unable to create temporary cache file /home/myusername/.ros/.rospack_cache.mnAamf: Permission denied

Taking ownership of the ~/.ros folder solved that.

sudo chown -R myusername ~/.ros 

---

Everything looked good with the subsequent tutorials till I had to run this in the Understanding ROS topics tutorial.

$ rosrun rqt_graph rqt_graph

Which returned

$ rosrun rqt_graph rqt_graph
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/rqt_graph/rqt_graph", line 5, in 
    from rqt_gui.main import Main
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_gui/main.py", line 38, in 
    import rospy
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/__init__.py", line 49, in 
    from .client import spin, myargv, init_node, \
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/client.py", line 52, in 
    import roslib
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslib/__init__.py", line 50, in 
    from roslib.launcher import load_manifest
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslib/launcher.py", line 42, in 
    import rospkg
ImportError: No module named 'rospkg'

Seemed easy…so I run pip

$ pip install rospkg

and got it installed, and run rqt_graph again…to get this

$ rosrun rqt_graph rqt_graph
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/rqt_graph/rqt_graph", line 8, in 
    sys.exit(main.main(sys.argv, standalone='rqt_graph.ros_graph.RosGraph'))
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_gui/main.py", line 59, in main
    return super(Main, self).main(argv, standalone=standalone, plugin_argument_provider=plugin_argument_provider, plugin_manager_settings_prefix=str(hash(os.environ['ROS_PACKAGE_PATH'])))
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/main.py", line 349, in main
    from .perspective_manager import PerspectiveManager
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/perspective_manager.py", line 44, in 
    class PerspectiveManager(QObject):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/qt_gui/perspective_manager.py", line 48, in PerspectiveManager
    perspective_changed_signal = Signal(basestring)
NameError: name 'basestring' is not defined

It seemed like it had to do with my messy python setup. I considered fixing the basestring issue as it was a python 2 vs 3 compatibility issue. That brought up  another similar error and usually that’s a bad sign.

I gave up on a fixing that as it did not look critical, but thankfully I found out I could access the node graphs from rqt directly.

By running,

$ rqt

and heading to Plugins > Introspection > Node Graph, you could access the same functionality.

Also, in following the rqt_console tutorial, I had to run

$ rosrun rqt_console rqt_console

and

$ rosrun rqt_logger_level rqt_logger_level

…which could be replicated by running rqt like stated earlier, and going to Plugins > Logging > Console and also Plugins > Logging > Logger level

Alternatively, running

$ rqt_graph &

or

$ rqt_console &

or

$ rqt_logger_level &

works just as well.

I would be using that ad-hoc fix till cracks in this approach surface and probably prompt a full installation of ROS and possibly Python/Anaconda.

---

In running the tutorial on messages and services, my attempts to run catkin_make install failed with this

Traceback (most recent call last):
  File "/opt/ros/kinetic/share/gencpp/cmake/../../../lib/gencpp/gen_cpp.py", line 41, in 
Traceback (most recent call last):
  File "/opt/ros/kinetic/share/gencpp/cmake/../../../lib/gencpp/gen_cpp.py", line 41, in 
    import genmsg.template_tools
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/genmsg/template_tools.py", line 39, in 
    import genmsg.template_tools
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/genmsg/template_tools.py", line 39, in 
    import em
ImportError: No module named 'em'
    import em
ImportError: No module named 'em'

Installing empy fixed that

$ pip install empy

References:

http://answers.ros.org/question/126471/cmake-failed-catkin_pkg/

http://ros-users.122217.n3.nabble.com/error-massage-with-rospack-td1406092.html

Also, consider reviewing this to get Anaconda to play nice with other python installations.