unisat

Drone / UAV — Operations Guide

Profile keys: drone_small (2.5 kg) · drone_medium (5.0 kg) Template: mission_templates/drone_survey.json ·

1. Mission class

Payload computer for fixed-wing or multi-rotor UAVs. Mounts inside the airframe as a secondary flight computer (primary autopilot — Pixhawk / ArduPilot — still handles actuator control). UniSat handles:

on-board science / imaging payload;
radio link to the ground-station dashboard;
mission-phase state machine (preflight / takeoff / mission / landing);
telemetry authentication (HMAC) for command uplink.

2. Physical envelope

Parameter	Small	Medium
Mass cap	2.5 kg	5.0 kg
Dimensions (mm)	200 × 200 × 100	300 × 300 × 150
Volume (cm³)	4000	13500
Generation	0 W (battery only)	0 W
Consumption	8 W	15 W

3. Regulatory context

EASA Open category: A1 (<250 g payload) / A2 (<2 kg MTOM) / A3 (<25 kg).
EASA Specific category: required for BVLOS, night, or payload > 4 kg.
FAA Part 107 (USA): commercial drone certificate.
Geofence: hardware/firmware must enforce a configured geofence radius.
Radio: ISM 2.4 GHz (MAVLink 915 MHz in US, 868 MHz in EU) or licensed UHF for longer range.

4. Subsystem matrix

Subsystem	Status
OBC	✅
IMU (flight controller)	✅ (redundant to autopilot)
Barometer	✅
GNSS	✅
2.4 GHz MAVLink link	✅
Camera (multispectral)	✅
Payload (survey kit)	✅
ADCS / reaction wheels	❌
S-band	❌

Note: the autopilot (Pixhawk etc.) is NOT a UniSat subsystem; UniSat interfaces with it over MAVLink-over-UART. The payload computer’s IMU / barometer are secondary references, not the control loop.

5. Build

# Small (EASA Open A2):
cmake -B firmware/build-arm-drone-small -S firmware \
      -DCMAKE_C_FLAGS=-DMISSION_PROFILE_DRONE_SMALL=1
cmake --build firmware/build-arm-drone-small

# Medium (Specific / BVLOS):
cmake -B firmware/build-arm-drone-medium -S firmware \
      -DCMAKE_C_FLAGS=-DMISSION_PROFILE_DRONE_MEDIUM=1
cmake --build firmware/build-arm-drone-medium

(Drone profiles are not on the default make target-* recipe list — add a local alias if used frequently.)

6. Mission config

cp mission_templates/drone_survey.json mission_config.json

Key fields:

mission.competition.max_flight_time_min — battery-limited; 30 min typical.
mission.competition.max_altitude_m — set to regulatory limit (typically 120 m AGL).
mission.competition.geofence_radius_m — hard-stop radius around takeoff point.
subsystems.comm.uhf.frequency_mhz — 2400 MHz MAVLink or licensed UHF.
subsystems.payload.sensors — list of survey sensors (multispectral, thermal, LiDAR).

7. Mass & volume validation

Validator-confirmed (default subsystems):

Size	Mass	Limit	Volume used
Small	1.8 kg	2.5 kg	45 % of 4000 cm³
Medium	3.2 kg	5.0 kg	38 % of 13500 cm³

8. Typical mission phases

Drone-survey phases (DRONE_SURVEY in mission_types.py):

preflight → armed → takeoff → mission_flight
                                  ↓
                        return_to_home / landing / emergency
                                  ↓
                              landed

Loss-of-link behaviour:

Beyond geofence_radius_m → return_to_home.
No link for > 60 s and outside RTH range → emergency (controlled descent).
Battery < 15 % → landing.

9. Testing checklist (bench)

Legend: [x] = verified in software / CI / SITL (passes in the current release); [ ] = requires bench hardware, RF range test, or flight-day field activity — team must sign off manually.

IMU cross-check: UniSat IMU vs. autopilot IMU agree within 0.5°/s at rest.
MAVLink heartbeat received at 1 Hz from the autopilot over UART.
Geofence trigger at the configured radius in a hardware-in-the-loop test.
Camera records 4K 30 fps for 20 min without drop.
RTH altitude correctly set to the higher of (takeoff altitude + 50 m) and (current altitude).
Emergency-landing mode: drone commands LAND to the autopilot within 2 s of link loss + geofence breach.

10. Flight-day checklist

Pilot has valid A2 / Specific / Part 107 certificate.
Weather within manufacturer limits (wind < 8 m/s typical).
Geofence uploaded and verified on the autopilot ground-control screen.
Spotter present if required by the operation category.
mission_config.json signed + loaded; KeyRotationPolicy reports ok.
Camera SD card formatted, ≥ 32 GB free.
Battery check on all flight batteries (cell balance < 0.05 V).
Emergency RTH tested at 30 m AGL before the full mission.

11. Known limitations

UniSat is NOT the primary flight controller. Never route actuator commands through UniSat; the autopilot must have full authority at all times. UniSat advises; autopilot commands.
Battery-only operation — no solar; flight time is battery-limited.
GNSS-denied operation not supported in 1.3.x — drone profiles assume continuous GNSS fix. If you fly indoors, disable GNSS explicitly in mission_config and expect the return_to_home logic to degrade to a barometric hold.
No onboard weather sensing — local met data must come from an external station.

12. Post-flight debrief

Capture:

MAVLink telemetry log (autopilot-side).
UniSat’s own logs (IMU cross-check, mission-phase trace).
Camera + payload data.
Battery consumption per flight segment.

Analyse:

Geofence compliance (every point inside the polygon).
Maximum altitude vs. permit.
Payload coverage map (for survey flights).

File in docs/operations/flight_reports/.

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