Skip to main content

Autotune

PX4's autotune flies a short series of small, automatic attitude disturbances, measures how the vehicle responds, and computes rate and attitude gains. It is the fastest way to a good tune and the recommended first step before manual PID Tuning.

The standard 305ap firmware includes autotune for both multirotor and fixed-wing.

Before You Start​

  • The vehicle flies stably with the default gains in Altitude or Position mode. Autotune refines a working tune; it can't rescue an unstable one.
  • Vibration levels are acceptable (check a log in Flight Review). Soft-mount the board on its rubber isolators.
  • Filters are reasonable for your frame (see Filter Tuning).
  • Calm weather, plenty of open space, and a full battery.

Multirotor​

  1. Enable the autotune module: set MC_AT_EN = 1 (it is off by default) and reboot.
  2. Assign a switch or use QGroundControl's Autotune button (Vehicle Setup → PID Tuning → Autotune).
  3. Take off and hover in Altitude or Position mode at a safe height.
  4. Start autotune. The vehicle twitches on each axis in turn for about 20–40 seconds. Keep the sticks centred and be ready to take over.
  5. When QGroundControl reports success, land and disarm.

MC_AT_APPLY controls when the new gains are used:

ValueBehavior
0Log only; gains not applied
1Apply after disarm (default)
2Apply in the air (not recommended)

After a successful run, fly again and check the result. If it oscillates, restore the previous gains (save your parameters before autotuning) and tune manually. MC_AT_SYSID_AMP sets how hard autotune excites the vehicle; see the PX4 documentation before changing it.

Fixed-Wing​

  1. Fly in a stabilized mode (Stabilized, Altitude or Position) at a safe altitude with room to fly straight.
  2. Start autotune from QGroundControl or an RC switch. The plane makes small roll, pitch and yaw manoeuvres.
  3. Keep the plane level and in the air while it runs.

FW_AT_APPLY controls when the gains are used: 0 log only, 1 after disarm, 2 in the air (the default for fixed-wing).

See the PX4 autotune documentation for details on both vehicle types.

After Autotune​

  • Download the log and check rate tracking in Flight Review.
  • Fine-tune with PID Tuning if needed (for example a softer yaw, or faster altitude response).
  • Re-run autotune after significant changes: different propellers, motors, battery weight, or a new frame.