ds-crazyflie: Webots Simulation

(This is a compilation of the most important features taken from the Usage Guide.)

Screenshot of Webots Simulation

Installation

On your host system move into the root folder of the cps.asset.crazyflie GitHub project and execute the following commands:

$ cd ~/uniagent_ws/cps-asset/crazyflie2.x/simulation/ds-crazyflies-ext
$ chmod +x ./prepare.sh

# For Linux:
$ ./prepare.sh --linux

# For Windows:
$ ./prepare.sh

Then, build:

$ cd simulation.ds-crazyflies/docker/
$ sudo docker compose build

Starting

(For Linux) This allows to show the UI on the host system:

$ xhost +local:$USER

Workspace Setup

1. Terminal:

Start all services:

$ cd ~/uniagent_ws/cps-asset/crazyflie2.x/simulation/ds-crazyflies-ext/simulation.ds-crazyflies/docker
$ sudo docker compose up
[+] up 1/1
 ✔ Container ds-crazyflies-dev Recreated             0.0s 
Attaching to ds-crazyflies-dev

2. Terminal:

Enter the container and start the simulation:

$ sudo docker exec -it ds-crazyflies-dev bash
:# webots /ds/crazywebotsworld/worlds/crazyflie.wbt --batch

To configure the world and number of Crazyflies:

:# nano /ds/crazywebotsworld/worlds/crazyflie.wbt

3. Terminal:

Enter the container and start the backend:

$ sudo docker exec -it ds-crazyflies-dev bash

:# ros2 launch crazyflies framework.launch.py backend:=webots

4. Terminal:

Enter the container:

$ sudo docker exec -it ds-crazyflies-dev bash

Then, for each Crazyflie in Webots execute (change ID):

:# ros2 service call /crazyflie_webots_gateway/add_crazyflie crazyflie_webots_gateway_interfaces/srv/WebotsCrazyflie "id: 0"

requester: making request: crazyflie_webots_gateway_interfaces.srv.WebotsCrazyflie_Request(id=0)
response:
crazyflie_webots_gateway_interfaces.srv.WebotsCrazyflie_Response(success=True, msg='')

The backend will report something like: [gateway-1] [INFO] [1265723145.816038468] [cf0]: CrazyflieWebots node initialized.]

5. Terminal:

Start cf.PyControl for each virtual Webots instance:

  • Make sure you have completed the Getting Started Guide for cf.PyControl.
  • Start the cf.PyControl Docker container
  • Then, execute:
:# ./cfpyctrl.sh --dscf --cf-prefix /cf0 --port 5000 --wsendpoint --wsport 8765

For more drones:

:# ./cfpyctrl.sh --dscf --cf-prefix /cf1 --port 5001 --wsendpoint --wsport 8766
:# ./cfpyctrl.sh --dscf --cf-prefix /cf1 --port 5002 --wsendpoint --wsport 8767
[...]

Usage

Controlling the Crazyflie

Reuse terminal 4 or open a new terminal to control the Crazyflie using cf.PyControl in the usual way.

Example:

$ curl -d {} http://127.0.0.1:5000/activate_idle
$ curl -d {} http://127.0.0.1:5000/begin_takeoff
$ curl -d {} http://127.0.0.1:5000/navigate/1.0/1.0/0.5
$ curl -d {} http://127.0.0.1:5000/navigate/0.0/0.0/0.5
$ curl -d {} http://127.0.0.1:5000/begin_landing

Troubleshooting

GUI not starting

Error:

Authorization required, but no authorization protocol specified
Warning: could not connect to display :1
Warning: From 6.5.0, xcb-cursor0 or libxcb-cursor0 is needed to load the Qt xcb platform plugin.
Info: Could not load the Qt platform plugin "xcb" in "" even though it was found.
Fatal: This application failed to start because no Qt platform plugin could be initialized.

Cause:
The container is not allowed to access the host X11 display.

Fix:

  • xhost +local:$USER
  • Restart the container and relaunch Webots.
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