Installing ETHz RotorS
Another drone simulator with potential

Let’s try another drone simulator! This time it is ETHzürich Autonomous Systems Lab RotorS. The simulator could be found on ETHZ-asl/rotors_simulator repo. The file there is full of instructions on how to install it, but I went over a few bumps to get it running. That journey is described here.

ETHz RotorS

I have ROS installed already; so, I started creating a new workspace:

mkdir -p ~/projects/Simulators/ethz-asl/src
cd ~/projects/Simulators/ethz-asl/src
catkin_init_workspace  # initialize your catkin workspace
wstool init
wstool merge rotors_hil.rosinstall
wstool update

Then I installed python_catkin_tools. Following the instruction:

sudo apt-get install python-catkin-tools

Trying to build the project I got this error:

catkin build
ImportError: "from catkin_pkg.package import parse_package" failed: No module named catkin_pkg.package

Make sure that you have installed "catkin_pkg", it is up to date and on the PYTHONPATH.

After googling it for a while, I noticed this post:

On the comments I saw:

Have you installed anaconda? If yes, maybe you should commet the anaconda path in .bashrc

I did have miconda installed. That works to get into another problem:

catkin build
    from future import standard_library
ImportError: No module named future

Googling it again, found:

I have to install the module future but I didn’t have pip installed, so:

sudo apt-get install python-pip

and then:

sudo pip install future

Notice that is not futures it is only one future what we need:

pip list | grep fut
future (0.17.1)
futures (3.0.5)

Here we go again to yet another error:

CMake Error at /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
  Could not find a package configuration file provided by "octomap_msgs" with
  any of the following names:


A missing package, I will try to install octomap but it was already installed:

sudo apt-get install ros-kinetic-octomap
Reading package lists... Done
Building dependency tree       
Reading state information... Done
ros-kinetic-octomap is already the newest version (1.8.1-0xenial-20180809-134711-0800).
ros-kinetic-octomap set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

I needed the messages:

sudo apt-get install ros-kinetic-octomap-msgs

Almost there:

catkin build
Could not find a package configuration file provided by "octomap_ros" with
  any of the following names:


Missing package octomap_ros (it was on the instructions, but I didn’t see it):

sudo apt-get install ros-kinetic-octomap-ros

This is it! Nop, another missing library:

catkin build
CMake Error at /usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
  Could NOT find GeographicLib (missing: GeographicLib_LIBRARIES

After googling, it found:

sudo apt-get install libgeographic-dev
sudo apt-get install geographiclib-tools

Another missing library glog:

catkin build
 Failed to find glog - Could not find glog include directory, set
  GLOG_INCLUDE_DIR to directory containing glog/logging.h

Google is your friend (it was also in the instructions, but I miss this one too):

sudo apt install libgoogle-glog-dev

After missing two many libraries, I think it is better to re-read the instruction again. Re-reading the initial documentation, I found I forgot to install a couple of packages:

sudo apt-get install protobuf-compiler ros-kinetic-mavlink

But still no joy. The installation continues and took a while building and running tests but still have a compilation error this time:

rotors_hil_interface/hil_interface.h:105:3: error: ‘mavlink_hil_gps_t’ does not name a type
   mavlink_hil_gps_t hil_gps_msg_;

Googling I found this issue

Based on that, I need to ignore the rotors_hil_interface for now:

touch src/rotors_simulator/rotors_hil_interface/CATKIN_IGNORE

This time everything works:

catkin build
[build] Summary: All 16 packages succeeded!    
[build]   Ignored:   2 packages were skipped or are blacklisted.        
[build]   Warnings:  None.                                              
[build]   Abandoned: None.                                              
[build]   Failed:    None.                                              
[build] Runtime: 7.2 seconds total. 

There is no warning here, but if we clean (catkin clean) and then build again you can see a couple of warnings.

[build] Summary: All 17 packages succeeded!       
[build]   Ignored:   2 packages were skipped or are blacklisted.   
[build]   Warnings:  3 packages succeeded with warnings.           
[build]   Abandoned: None.                                         
[build]   Failed:    None.                                         
[build] Runtime: 4 minutes and 32.2 seconds total.                 
[build] Note: Workspace packages have changed, please re-source setup files to use them.

The packages with warnings were:

Everything should be fine! Let’s try to run it:

roslaunch rotors_gazebo mav_hovering_example.launch mav_name:=firefly world_name:=basic

Gazebo starts and the drone hovers:

ETHz RotorS hovering

That is a good start! To get more info rosrun rqt_graph rqt_graph:

ETHz rqt_graph

The documentation specifies the topic /firefly/command/motor_speed to receive mav_msgs/Actuators messages to command the rotors angular velocity.

The installation was a long journey, but not so hard to have RotorS running. It is time for new adventures!

Happy droning!

Written by Darien Martinez Torres on 15 November 2018