1. Subscribersonhouse
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    08 May '15 11:32
    http://phys.org/news/2015-05-zurich-team-high-speed-tethered-quadrocopters.html

    They are doing some significantly impressive maneuvers!
  2. Cape Town
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    08 May '15 11:55
    You can do a free course on how to program them on edX. Its conducted by the university of Munich (Technische Universität München)
    You need some math and programming skills.
  3. Subscribersonhouse
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    08 May '15 12:19
    Originally posted by twhitehead
    You can do a free course on how to program them on edX. Its conducted by the university of Munich (Technische Universität München)
    You need some math and programming skills.
    The physical specs are as impressive as the programming! Those little drones were pulling 13 G's!
  4. Cape Town
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    08 May '15 12:461 edit
    Originally posted by sonhouse
    The physical specs are as impressive as the programming! Those little drones were pulling 13 G's!
    There is nothing about their construction that would make that any harder. Electric motors work just find under acceleration.
    If anything tethered flight is easier as it reduces the degrees of freedom. It does allow faster flight in combined space which is what they were demonstrating.

    I would think that GPS would be useless at those speeds and even video cameras might struggle to keep up making visual position control difficult.
  5. Subscribersonhouse
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    08 May '15 15:42
    Originally posted by twhitehead
    There is nothing about their construction that would make that any harder. Electric motors work just find under acceleration.
    If anything tethered flight is easier as it reduces the degrees of freedom. It does allow faster flight in combined space which is what they were demonstrating.

    I would think that GPS would be useless at those speeds and even video cameras might struggle to keep up making visual position control difficult.
    well, in the real world, they would't be 2 meters apart, more like 20 meters. Even in that case GPS would not be reliable since at best you get there is 1 meter or 2. So it would have to rely on good inertial nav system, some kind of gyro affair maybe.
  6. Cape Town
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    08 May '15 15:58
    Originally posted by sonhouse
    well, in the real world, they would't be 2 meters apart, more like 20 meters.
    Those were very real quadcopters.

    Even in that case GPS would not be reliable since at best you get there is 1 meter or 2.
    It is nevertheless useful in navigation over small distances. If you average out the readings you can actually get better than 1m relative accuracy (not absolute accuracy but that doesn't matter).
    My concern was how long it takes to get a reading. If it takes more than a few milliseconds, then at those speeds, the quadcopter has moved and the reading is not as much use.

    So it would have to rely on good inertial nav system, some kind of gyro affair maybe.
    Yes, the quad copters have accelerometers similar to the one in a smartphone. They also use cameras for estimating motion. But digital cameras have a limit to how fast an object is moving before it becomes a blur. Also the computing speed of the onboard computer might struggle to keep up at those speeds. You have to take a photo, compare it to the previous photo then estimate how far you have moved between frames. If you travel twice as fast, you have to compute twice as fast or loose some accuracy.

    I did the course I mentioned earlier and got 99% 🙂
  7. Subscribersonhouse
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    08 May '15 17:12
    Originally posted by twhitehead
    Those were very real quadcopters.

    [b]Even in that case GPS would not be reliable since at best you get there is 1 meter or 2.

    It is nevertheless useful in navigation over small distances. If you average out the readings you can actually get better than 1m relative accuracy (not absolute accuracy but that doesn't matter).
    My concern was how long ...[text shortened]... ute twice as fast or loose some accuracy.

    I did the course I mentioned earlier and got 99% 🙂[/b]
    That course is all online? How much does it cost?
  8. Cape Town
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    09 May '15 07:19
    Originally posted by sonhouse
    That course is all online? How much does it cost?
    It is free if you do not need a verified certificate or university credit.
    https://www.edx.org/

    They just started a re-run on 5th May. If you don't care about marks or just want to browse, then you can simply sign up and watch just the videos. I wouldn't recommend that particular course unless you have a maths and programming background, but there is no harm in looking.

    I have done a lot of courses on edX. Its fantastic. You learn a lot more if you do all the exercises. Some courses I just don't have the time, or don't want to put in the effort so I just watch the videos, and some I go all out and try to get good marks and they do give you a certificate although it is not verified so you can't prove you didn't have someone else do it for you. They have courses from top institutions (Harvard, MIT, Caltech. Berkley)
    Some courses run on a strict schedule and you must catch them at the right time, others are self paced.

    I have just finished watching the videos of an MIT course on DNA replication. I was too busy to do the exercises (they are difficult and have a 1 week deadline). I do at least now have a basic understanding of how DNA replicates. Very interesting.
    Also, it is up to date science. Most of what I learnt in the MIT course was not known at the time I was at University 20 years ago.
  9. Subscribersonhouse
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    09 May '15 14:25
    Originally posted by twhitehead
    It is free if you do not need a verified certificate or university credit.
    https://www.edx.org/

    They just started a re-run on 5th May. If you don't care about marks or just want to browse, then you can simply sign up and watch just the videos. I wouldn't recommend that particular course unless you have a maths and programming background, but there is ...[text shortened]... t of what I learnt in the MIT course was not known at the time I was at University 20 years ago.
    For those who don't know what that is, here is a Wiki on it:

    http://en.wikipedia.org/wiki/EdX
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