drone-follow-dev

name	drone-follow-dev
description	Day-to-day dev loop for drone-follow on the laptop — run sim + drone-follow with web UI, free port conflicts, kill cleanly. Use when the user says "run drone-follow with sim" / "start the simulator" / "kill drone-follow".

Drone-follow dev loop

Two terminals: start_sim.sh in one, drone-follow in the other. Repo at /home/giladn/tappas_apps/repos/hailo-apps-infra; sub-project at community/apps/hailo_drone_follow.

Pre-checks

Run these first when the user asks to start a session.

# 1. Are sim processes already running?
ps -ef | grep -E "px4|gz sim|video_bridge|start_sim" | grep -v grep

# 2. Is UDP 5600 (video) free? Common offender: QOpenHD.
ss -tunlp 2>/dev/null | grep -E ":5600|:14540"

# 3. Is the venv on PATH? `which drone-follow` will fail in non-login shells —
# remind the user they need `source setup_env.sh` in their interactive terminal.
ls /home/giladn/tappas_apps/repos/hailo-apps-infra/venv_hailo_apps/bin/drone-follow

If 5600 is held by QOpenHD, kill QOpenHD first or close its window. Drone-follow can't receive video while it's bound.

Worlds available

List with ls community/apps/hailo_drone_follow/sim/worlds/. Common picks:

• 2_persons_diagonal — two static persons, separated diagonally — good for testing AUTO-mode largest-person selection and lock switching.
• 2_person_world — two persons close together — ReID drift / reacquire stress.
• random_walk — moving target — ByteTracker continuity test.
• walk_across_then_approach — distance + size variation.

Run

Terminal 1 — sim:

cd /home/giladn/tappas_apps/repos/hailo-apps-infra/community/apps/hailo_drone_follow
sim/start_sim.sh --bridge --world <world-name>

First run takes 10–20 min for PX4 build (sim/setup_sim.sh if it's a fresh clone). Subsequent runs ~10 s to PLAYING.

Terminal 2 — drone-follow with web UI:

cd /home/giladn/tappas_apps/repos/hailo-apps-infra/community/apps/hailo_drone_follow
source setup_env.sh
drone-follow --input udp://0.0.0.0:5600 --takeoff-landing --webui

Web UI: http://localhost:5001 (override via --webui-port).

Common variations:

• Add --display if you also want the local X11 window with overlay (the implicit-display rule turns it off when --webui is set).
• Add --no-yaw-only for full follow with forward/backward control. Default --yaw-only is the safe choice with the simulator's vision camera.
• Drop --takeoff-landing if you want the drone already airborne (e.g., joystick-controlled).
• USB camera + sim ⇒ must add --yaw-only — webcam sees the real world, forward commands based on bbox-size are unsafe.

Kill cleanly

ps -ef | grep -E "drone[-_]follow|start_sim|video_bridge|px4|gz sim" | grep -v grep | awk '{print $2}' | xargs -r kill
sleep 2
# if anything's still alive:
ps -ef | grep -E "drone[-_]follow|start_sim|video_bridge|px4|gz sim" | grep -v grep | awk '{print $2}' | xargs -r kill -9
ss -tunlp 2>/dev/null | grep -E ":5600|:14540"   # both should be empty

start_sim.sh is the parent of the bridge + cmake + px4 + gz chain — it usually propagates SIGTERM to its children, but force-killing each PID is safer when the chain is half-stuck.

After build / pull / config change

Order:

1. Plugin .cpp/.hpp changed? → hailo-compile-postprocess install + rm -f ~/.cache/gstreamer-1.0/registry.x86_64.bin. See ../../memory/hailotilecropper_dynamic.md.
2. Web UI files changed? → cd robot_follow/ui && nvm use 20 && npm install && npm run build. See ../../memory/webui_build.md.
3. Just Python changed? → No rebuild. Just restart drone-follow.

Don't do

• Don't sudo install built .so files into /usr/lib/... outside of hailo-compile-postprocess install — the install script knows which artifacts go where.
• Don't run gst-launch-1.0 --gst-plugin-load=<built.so> while the system version of the same plugin is also installed; type-registration collides and segfaults at PLAYING. Install via hailo-compile-postprocess instead.
• Don't use openhd --clean-start to "reset" the air unit if it's paired with a working ground unit — see ../../memory/openhd_pairing.md.