This section contain those Frequently Asked Questions that pertain to "those commands" that are regularly used to interact with the ``D-FaLL-System`` and bring your control algorithms to life through a Crazyflie quadrotor.
### How do I to get a clean version of the repository?
<b>Step 1)<\b> Change to the directory where you have a copy of the ``D-FaLL-System`` repository under version control. On a machine setup as per the instruction this will be
<b>Step 1)</b> Change to the directory where you have a copy of the ``D-FaLL-System`` repository under version control. On a machine setup as per the instruction this will be:
```
cd ~/work/D-FaLL-System
```
Step 2) It is good practice always check the status of the git repository,
``
<b>Step 2)</b> It is good practice always check the status of the git repository:
``''
git status
``
Step 3)
``''
<b>Step 3)</b> Remove all changes on the current branch since the previous pull
```
git checkout .
```
<b>Step 4)</b> Switch to the ``master`` branch of the repository
```
git checkout master
```
<b>Step 5)</b> Update to the latest version of the ``master`` branch from the remote repository
```
git pull
```
### How do I launch the ``Student GUI``?
The ``Student GUI`` can be launched from a terminal window with the following command:
```
roslaunch d_fall_pps Student.launch
```
This can be run from any directory because ``d_fall_pps`` is defined as an environment variable that points to the absolute foler location ```~/work/D-FaLL-System/pps_ws/src/d_fall_pps/launch/`
### How do I make changes to a ``*cpp`` file take effect?
In essence you need to re-compile the code and re-launch all ROS nodes.
<b>Step 1)</b> Kill all ROS processes that are running nodes from the ``D-FaLL-System`` repository, i.e., you must kill the ``Student GUI`` node but you do not need to kill an ``rqt`` plotting node. To kill a process press ``Ctrl+c`` from the terminal window that is running the process.
<b>Step 2)</b> In a terminal window, change to the ``pps_ws`` folder of the repository (where ``ws`` stands for workspace. On a machine setup as per the instruction this will be:
```
cd ~work/D-FaLL-System/pps_ws/
```
<b>Step 3)</b> Compile the repository, which includes your changes, using the command:
```
catkin_make
```
<b>Step 4)</b> Relaunch the Student GUI
## Troubleshooting :-(
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...
@@ -28,13 +63,13 @@ This section contains those Frequently Asked Questions that pertain to commonly
This can happen for a variety of reasons, and generally relates to the local computer not being able to access the "ROS core" that is running on the Teacher's computer. That error can be fixed by one or all of the following step:
Step 1) Check that the network cable is actually plugged, and that the lights of the ethernet port are actually flashing (this needs to be check both for the local computer and for the Teacher's computer that is running the "ROS core")
<b>Step 1)</b> Check that the network cable is actually plugged, and that the lights of the ethernet port are actually flashing (this needs to be check both for the local computer and for the Teacher's computer that is running the "ROS core")
Step 2) Check that the local computer's operating system is actually connected to the local network. This can be checked via the network icon on the right of the panel in Ubuntu (i.e., at the top right of the screen just near the battery level indicator)
<b>Step 2)</b> Check that the local computer's operating system is actually connected to the local network. This can be checked via the network icon on the right of the panel in Ubuntu (i.e., at the top right of the screen just near the battery level indicator)
Step 3) Sometimes other network connection disrupt the connection to the local network on which the ROS system communicating. Disable all other network connection via the network icon on the right of the panel in Ubuntu (i.e., disable WiFi)
<b>Step 3)</b> Sometimes other network connection disrupt the connection to the local network on which the ROS system communicating. Disable all other network connection via the network icon on the right of the panel in Ubuntu (i.e., disable WiFi)
Step 4) Close all terminal windows (and hence kill all processes running via a terminal window), then open a new terminal window and try to launch the Student GUI again.
<b>Step 4)</b> Close all terminal windows (and hence kill all processes running via a terminal window), then open a new terminal window and try to launch the Student GUI again.
To understand how Step 4) could actually fix the problem, consider that ``~/.bashrc`` is run when a new terminal window is opened, and as part of setting the ``D-FaLL-System`` the following line is added to the ``.bashrc``:
