Get a simulation working

[slim71]

Once the leader election is done, I'll need to move to simulations because of the fleet-managing component of the project. This will of course be a must for the project itself, but it would also be useful early on to actually see how the fleet behaves.

The goal is to have at least 2-3 copters in a simulation and getting to move them manually and together, with a single input.

[slim71]

As for now, the models modified and included have been tested in an empty world in Gazebo and they do work. Minimal tests were conducted:

• spinning the rotors
• lift-off
• stable hovering
• landing

[slim71]

A simple pre-arm checks + arm operation is working both with a single agent and in the overall example simulation at commit 098a912

[slim71]

Multi-agent synchronized operations are now achievable, as per commit 2a70004

[slim71]

Rendezvous is complete, even though it might require some fine-tuning in the future. For now, it is found at commit a0d386a