Drone Payload & Gimbal Control

What it does

From listening to the aircraft - to commanding it.

The MAVLink telemetry stack already ingested HEARTBEAT, GLOBAL_POSITION_INT, and attitude. Payload control promotes the gimbal from a planning parameter into a live, controllable attitude and adds outbound commands to the aircraft.

Gimbal attitude - target pitch (-90..+90), yaw (0..359), roll (-45..+45) via MAV_CMD_DO_GIMBAL_MANAGER_ATTITUDE (1000), with Follow / Lock / Free pointing modes.
Camera mode - switch the active sensor (RGB ↔ Thermal) via MAV_CMD_SET_CAMERA_MODE (510).
Zoom - command optical/digital zoom via MAV_CMD_SET_CAMERA_ZOOM (531).
Type auto-detection - CAMERA_INFORMATION (259) + vendor heuristic → RGB / Thermal / LiDAR / Multispectral.

POST /api/payload/command

// point the gimbal nadir, lock yaw north
{
  "sysId": 1,
  "pitchDeg": -90,
  "yawDeg": 0,
  "mode": "Lock"
}
→ MAV_CMD 1000 sent
→ status reflects GIMBAL_DEVICE_ATTITUDE_STATUS
{ "accepted": true, "gimbalPitchDeg": -90 }

Multi-sensor payload control panel with gimbal attitude, RGB/thermal toggle, and zoom slider

The telemetry that drives it

Inbound MAVLink → outbound MAVLink

Payload status is assembled from the same MAVLink stream the telemetry overlay already decodes. The command-send path reuses that link so every command rides the connection that's already proven up.

🧭

Attitude status

GIMBAL_DEVICE_ATTITUDE_STATUS (285) → live pitch/yaw/roll, quaternion→euler.

📷

Camera info

CAMERA_INFORMATION (259) → sensor type + mode from cam_definition_uri or heuristic.

💓

Heartbeat scoping

Component IDs from HEARTBEAT identify gimbal/camera components per sysId.

🎯

Pointing modes

Follow (yaw trails flight direction), Lock, Free - mapped to GIMBAL_MANAGER_FLAGS.

🔄

Staleness tracking

?sysId + ?staleSec on status so stale attitudes are flagged, not trusted.

🛡️

Never-throws sends

Every command send returns a result object; a dead link is reported, never raised.

REST API surface

Command the payload from your own UI

Capability	Endpoint	MAVLink
Capability discovery	GET /api/payload/capabilities	Available sensors + gimbal presence
Payload status	GET /api/payload/status	Live attitude + mode (`?sysId`, `?staleSec`)
Gimbal command	POST /api/payload/command	MAV_CMD 1000 - pitch/yaw/roll + mode
Camera mode	POST /api/payload/camera/mode	MAV_CMD 510 - RGB ↔ Thermal
Camera zoom	POST /api/payload/camera/zoom	MAV_CMD 531 - zoom level

Command mapping reflects PayloadService. This is the first feature that sends MAVLink commands; earlier features (FlyPath, telemetry overlay) were receive-only. Actual gimbal response depends on the airframe's MAVLink gimbal protocol support.

Part of the UAS loop