How to programmatically send signals to the Faster GUI?

[yanmiao2]

Hi developers, I'm wondering instead of manually clicking on the "Start", "Stop" Emergency Stop" buttons in the Faster GUI every time we start/stop the drone, is there a way to programmatically enable those signals like using a python script?

[jtorde]

Hi @yanmiao2,

You can run rosservice call /change_mode 'mode: 1' from the terminal (or from Python/C++ using system(...)), and it should have the same effect

[jtorde]

Closing this for now, feel free to reopen if you are still facing this issue

[yanmiao2]

Hi @jtorde, thanks for the reply! I tried the solution you proposed, but am getting this error ERROR: service [/change_mode] responded with an error: service cannot process request: service handler returned None

Also, just to clarify, is "start" mode 1, "end" mode 2, and "e_stop" mode 3?

[yanmiao2]

Also a separate question: I'd like to write a function to check the status (E.g. Is destination the obstacle? Did drone collide with walls?...) of the drone at any time. Is there an existing function/log in faster that I can directly work on?

Sorry for so many questions, since I'm very new to ROS and am trying to figure things out. I deeply the efforts developers invested in this project. Thanks in advance!

[jtorde]

For the service question, could you try again with the last commit? It's working now on my end (I still get the message service handler returned None on the terminal, but the drone does take off/land): rosservice call /change_mode "mode: 1"

The convention is

uint8 START  = 1
uint8 END    = 2
uint8 KILL   = 3

(see file MissionModeChange.srv)

For the second question: Right now there are no logs in faster that do those checks directly. One way would be to create a Gazebo plugin to check the collisions, and another one to record a rosbag and do a post-analysis using this. You can also have a look at this file (from the MADER repo) to run many simulations and detect the terminal condition.

Hope this helps!