PX4 integration

[petergerten]

Did anybody integrate PX4 SITL with this framework to utilize it for higher level objectives?

[JacopoPan]

Hi @petergerten , no, so far no one has worked on PX4 integration yet.

[dmvinson]

What would be involved in integrating with PX4? Is that covered under the Use SITL services with steppable simulation roadmap item? I'd be interested in this for my work, happy to contribute if there is an initial set of pointers to being development

[JacopoPan]

Hi @dmvinson

if you want to try and implement a lockstep version of PX4 SITL paired with one of the environments in this repo, it would be great and I'm happy to advise/guide/PR review the process.

I would start from the example in beta.py for which the execution instructions are here.

In this case the SITL is NOT in lockstep (the PyBullet simulation and the SITL of Betaflight run in parallel in separate processes

gym-pybullet-drones/gym_pybullet_drones/envs/BetaAviary.py

Lines 85 to 89 in 3d7b12e

	# Spawn SITL Betaflight instances (must have been created with assets/clone_bfs/sh first)
	for i in range(num_drones):
	FOLDER = os.path.dirname(os.path.abspath(__file__))+'/../../betaflight_sitl/bf'+str(i)+'/'
	cmd = f"gnome-terminal -- bash -c 'cd {FOLDER} && ./obj/main/betaflight_SITL.elf; exec bash'"
	subprocess.Popen(cmd, shell=True)

and communication happens over UDP

gym-pybullet-drones/gym_pybullet_drones/envs/BetaAviary.py

Lines 158 to 163 in 3d7b12e

	# print("rc", struct.unpack('@dHHHHHHHHHHHHHHHH', rc_packet))
	self.sock[j].sendto(rc_packet, (self.UDP_IP, BASE_PORT_RC + 10 * (j))) # drone0 will be on 9004, drone1 on 9014, etc.
	#### PWMs message from Betaflight ##########################
	try:
	data, addr = self.sock_pwm[j].recvfrom(16) # buffer size is 100 bytes (servo_packet size 16)

I believe that something similar using the default UDP/TCP port of SITL PX4 (see this diagram) and WITH THE ADDITION of lockstep execution (see this paragraph could be implemented by creating a new example gym_pybullet_drones/examples/px4.py and a new environment (spawning and talking to PX4 SITL) gym_pybullet_drones/envs/PX4Aviary.py

[dmvinson]

Thanks for the guidance, I'll take a look at this over the next few days. I appreciate your help!