Autonomous Helicopter Learns Autorotation

Stanford’s autonomous helicopter group has made some impressive advancements in the field of autonomous helicopter control, including inverted hovering and performing aerobatic stunts. The group uses reinforcement learning to teach its control system various maneuvers and has been very successful in doing so. One of their latest achievements was teaching the bot the emergency landing technique autorotation. Autorotation is used when a helicopter’s engine fails or is disengaged and works by changing the collective pitch to use the airflow from descent to rotate the blades. The group has more flight demonstrations on their YouTube channel.

[via BotJunkie]

10 thoughts on “Autonomous Helicopter Learns Autorotation

  1. Do real, full-size heli’s have emergency automatic autorotation?
    It could be a life-saving feature if an aircraft is lost power, and/or the pilot loses conciousness (or worse).

  2. Good to know…but that video is so very repetitive and redundant. I think I got it after the first four repetitions. Perhaps they could have drawn some diagrams or explained stuff instead of just repeating the technique over and over with a helicopter that’s too small to see details on.


  3. Aud1073cH:

    Its not automatic, but a pilot can do it. You reverse the pitch of the blades to negative pitch so falling through the air spins your unpowered blades faster. Then you take that stored up kinetic energy in the blade speed and reverse the pitch so it stops your descent right above the ground. A skilled RC pilot can do this with a model as well.

  4. #3, thanks captain obvious, nobody would have though about this. Before realising that… autorotation is used against engine failure, not pilot failure. So keep your warm’n’fuzzy feel good bullshit for your next “mother against something” meeting.

  5. @dave

    Ehh, the blades don’t “reverse pitch to negative”. That would send you plummeting to the ground. The range of pitch of the blades are no different when your autorotating than when you are flying normally. You simply adjust the collective (blade pitch) to regulate your decent just like you would if they were being powered. The only difference is the air coming up through the blades from your decent keeps them going instead of the engine. If you arrest the decent, the rotor speed will drop….and so will you.

  6. @mike

    You’re right, the blades are essentially ‘gliding’ in their plane of rotation, which takes constant adjustment of the cyclic pitch, note that’s only valid for forward a flight path and not intuitively obvious. If you were to land at this constant velocity, you’ll spread the skids (at least).

    Before landing, flare to increase blade speed and slow forward motion, increase the collective, arresting your descent at a moment before meeting the ground, but there’s only one chance.

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