Introduction to drone Swarming with Ardupilot

sprained_ankle · November 22, 2020, 11:36am

I recently have been exploring and learning about ardupilot’s multi drone control features. I went ahead and put together a few video tutorials that go over the following

Simulating Multiple Drones With Gazebo
https://youtu.be/r15Tc6e2K7Y)
Connecting Multiple Drones to QGroundcontrol
https://youtu.be/UWsya46ZG4M
Controlling Multiple Drones With MAVROS
https://www.youtube.com/watch?v=kcCL0w4NbIc

I know that there is a lot more you can do with swarming, but I believe the above tutorials can be a good jumping off point for people starting to experiment with swarming.

each of the above tutorials have accompanying text tutorials on my github aswell, which you can find here

Simulating Multiple Drones With Gazebo
connecting multiple Drones to QGroundcontrol

github.com

Intelligent-Quads/iq_tutorials/blob/master/docs/swarming_ardupilot.md

# Swarming Using Ardupilot

## Video Tutorial at https://youtu.be/r15Tc6e2K7Y

This tutorial shows you how to model and control a swarming using ardupilot and Gazebo

## Pre-rec

add the models folder in the iq_sim repo to the gazebo models path
```
echo "export GAZEBO_MODEL_PATH=${GAZEBO_MODEL_PATH}:$HOME/catkin_ws/src/iq_sim/models" >> ~/.bashrc
```


## Connecting Multiple Vehicles SITL to Gazebo

You should think about ardupilot as purely a control system. It takes sensor inputs and outputs commands to actuators. Gazebo is playing the role of a Flight Dynamics Model (FDM). The FDM encompasses all of the following, sensor models, actuator models and the dynamics of the vehicle. In real life ardupilot would communicate with your sensors via serial connections, but when you run SITL with gazebo ardupilot talks to the sensors and actuators via UDP connections (an IP protocol). Because of this we will need to specify different UDP ports in our robot models such that these streams do not conflict. 

Lets start by copying the drone1 folder in `iq_sim/models` and paste it as a copy. rename the folder to drone2.

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Controlling Multiple Drones With MAVROS

github.com

Intelligent-Quads/iq_tutorials/blob/master/docs/multi_mavros_drones.md

# Controlling Multiple Ardupilot Drones Via MAVROS



In this tutorial you will learn how to use the iq_gnc functions to control multiple drones on the same ros network.

## Launching a MAVROS Instance for Each Drone

Each ardupilot SITL instance creates a couple of unique MAVlink streams. This is shown in your mavproxy terminal when you launch your ardupilot instance. For example when launching ardupilot with the below launch options 

```
sim_vehicle.py -v ArduCopter -f gazebo-drone2 -I1
```
the output mavlink streams are show as follows
```
SIM_VEHICLE: "mavproxy.py" "--master" "tcp:127.0.0.1:5770" "--sitl" "127.0.0.1:5511" "--out" "127.0.0.1:14560" "--out" "127.0.0.1:14561"
```

We will need to tell MAVROS which udp interface to use for the drone we want MAVROS to connect to. For this vehicle the interface we will be using is 14561. To tell MAVROS to use this port we will launch with the following 
```

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I hope the above information is helpful!

ppoirier · November 22, 2020, 11:38am

Very informative, thanks.
Please note I added a screen capture of your video to make the blog more catchy.

khancyr · November 22, 2020, 2:22pm

Very nice !
We have seen this some time ago and were speaking about adding some part on the wiki to help newcomers !

Some tips :

to set the SYSID_THISMAV, we have now a --sysid cmdline option !
QGC support multicast connection, so using --mcast will be simpler than manually setting a output to 0.0.0.0:xyz
with more than 3 vehicles, that is better to not load mavproxy for performance: --no-mavproxy cmdline
--add-param-file to append a parameter file on loading instead of modifying vehicleinfo.py

There is also a swarm launcher on sim_vehicle.py that need some documentation

Notorious7 · November 22, 2020, 3:32pm

I am looking to simulate about 500 drones or even more, I know running these much of ardupilot SITL instances does not look feasible on same machine, my current system starting to getting laggy after starting 16 SITL instances and even after that on my system there doesn’t seem any platform which is capable of simulation of more than 16 drones properly, right now I am using MQTT to exchange messages across multiple python scripts each running their own SITL instances, but these messages starting to get lag when running multiple SITL instances, that’s why this lag messed up the swarming logics and other stuffs but on actual drones things work properly, is there any way around doing simulations of 500 or more drones ? One way I can guess is running multiple SITL instances on multiple systems and exchange MQTT messages across AWS EC2 and then receive MQTT messages coming from multiple systems on a single system which will be running simulation platform like gazebo, blender or something else, but this setup is not practical and too expensive

sprained_ankle · December 9, 2020, 3:15am

I apologies. I actually made this post then went on vacation These are all things I was completely unaware of! I am going to experiment with these features and update my tutorial once I get a handle on how they all work together!