Set-Up: SITL with MATLAB Physics Backend

ArduCopter Copter Simulation
1

Hello,

I’m trying get the SITL environment working, but ran into some issues when trying to use my own model, which is implmented in MATLAB/Simulink. For now I’m trying to get the example from the official doc to work, but no luck so far.

If I start the provided MATLAB script and run

sudo ./Tools/autotest/sim_vehicle.py -v ArduCopter -f json:<IP_ADRESS> --console

inside the WSL a VsXsrc X Server window opens and displays

Set parameter SIM_SPEEDUP to 1.000000
Vehicle model (json:<IP_ADRESS>) not found

VSCode Terminal Output:

SIM_VEHICLE: Run ArduCopter
SIM_VEHICLE: "<...>/ardupilot/Tools/autotest/run_in_terminal_window.sh" "ArduCopter" "/home/oskar/ardupilot/build/sitl/bin/arducopter" "-S" "-I0" "--model" "json:128.131.203.104" "--speedup" "1"
SIM_VEHICLE: Run MavProxy
SIM_VEHICLE: "mavproxy.py" "--master" "tcp:127.0.0.1:5760" "--sitl" "127.0.0.1:5501" "--out" "127.0.0.1:14550" "--out" "127.0.0.1:14551" "--console"
RiTW: Starting ArduCopter : /home/oskar/ardupilot/build/sitl/bin/arducopter -S -I0 --model json:<IP_ADRESS> --speedup 1
Connect tcp:127.0.0.1:5760 source_system=255
[Errno 111] Connection refused sleeping
[Errno 111] Connection refused sleeping
[Errno 111] Connection refused sleeping
[Errno 111] Connection refused sleeping
Failed to connect to tcp:127.0.0.1:5760 : [Errno 111] Connection refused
SIM_VEHICLE: MAVProxy exited
SIM_VEHICLE: Killing tasks

Set-Up: Win10, MATLAB R2021a, VisualStudio Code + WSL, ArduCopter 4.0.7.
Running the SITL with MavProxy and connecting to Mission Planner works fine.

Any ideas?
Thanks.

2

What version of WSL (1 or 2)? What version of ArduCopter? I had better luck when starting the physics first and then SITL.

3

I always start the physics backend first and then launch the ArduPilot SITL.
I’m using WSL 1. I’ll try upgrading to Version 2 and see if that works.

4

WSL1 should work fine, I suspect your problem is ArduCopter 4.0.7 try on latest.

5

That solved it. Thank you very much @iampete !

6

I have a little follow up question for all the STIL experts here. Let me give you a little context first: I built an Eletric Ducted Fan UAV (“SingleCoper” Frame), got it flying pretty well and built a model in MATLAB, which I am now trying to validate against real flight data.

  1. Method: feed Servo (RCOut) data to the MATLAB model and compare simulated IMU and attitude data against the actual one.
  2. Method: feed recorded desired Angles/Rates/Throttle (RCIn) data to the SITL (Ardupilot Controller + MATLAB model) and, again, compare the simulated against the real data.

I already tried the first method and it yielded good results, however doing trying to validate a model like that is probelmatic on many levels, which is why I’m currently working on making the second method work.

  • How would one preferably set this up (high level)? At the moment I’m running the ardupilot SITL and the physics backend in MATLAB/Simulink. However to my knownledge there’s no way to automatically feed the RCIn/Desired Attitude/Throttle values to the SITL. Can this be done? Preferably also via MATLAB using the JSON Interface.
7

No way to do this currently, you would have to add something.

8

Yeah i’d love to contribute something. As far as I can tell you did a lot of work in that department. Would you be interested in collaborating? If so, is there any way to get in touch?

9

Hi Oskar,

Best place is the simulation channel over on the developer discord, https://discord.gg/YDRS4cHq

We would love some more vehicle examples.