Bitcraze Forums

Hi all,
I can't figure out how to make make my CF do a flip at the command of a button. I set the max angle rate to 360, and double tapped the analog stick on my Xbox 360 controller to make it flip. It works, but usually hits the floor because the downward force is so great. Is there any way to assign this to a button (I was thinking D-Pad) and have it flip faster? I would prefer it to not hit the ground each time because after a while, it will break. I am rather a newbie at this so any advice would be helpful.

Thanks,
Ben Stout

"To be, not to live, to flie"
-ben.young

Ben,
Not sure if there's a enough thrust for the flie to recover after the momentum of the drop. Mapping one of the D-pad keys would require re-coding. If you haven't already, I would increase the max thrust limit from 80 to 99.9 and see if that allows you to recover before hitting the floor.

You're the first flier I've heard of that's looked into flipping. Let us know how it goes!

P.S. A video would really help!

I'm guessing you want a short full thrust. Then cut the thrust and invert. Then invert back and add another burst of full thrust. A bit like having a plate on your hand. rasing it quickly and then inverting it. So its upside down on your hand without holding it there, momenteraly. Note that you do not have access to reverse thrust. I'm not 100% sure the maths works out correct with the fly inverted. The reason I say that is I added a cut out for high pitch or high roll (magnetude) that did not seam to work when the flie was inverted. (in my case crashed to the floor upside down) So I added a seperate cutout for when inverted. (accel z negative). This should be easy to check by hand waving it around and looking at the PC client.

Another thing you may want to do is cut the thrust automatically when inverted. Thrust demand upside down does not make much sense.

Hey, i have carried out many successful flips (one very unsuccessful which led to and arm snapping!!)

To do this I put the flie into rate mode, when the flie is set to 360 in angle mode it is very uncontrollable, rate mode isn't the easiest to fly in though when you are used to angle mode.

Once in rate all you need to do is full thrust vertically for about 1 meter (make sure you have at least 3-4meters of height). Once at the top, very quickly pull back on the roll stick in the direction you want to flip, towards you is easiest. As you quickly pulled back on the stick fully let go of the thrust and let the flie fall/roll over on itself. Once you have seen it has fallen to relatively level position, full thrust on!!

It is best to get used to floating around in rate mode first, and once in rate, to perform a flip you want a roll value of between 360-500.

Oh, and try practice on grass!!! I performed many upside down full thrust moves into the ground. But they are easy now I have practiced

Happy flipping!!

danhamilt1

It'd be awesome if you could get a video sometime danhamilt1 - of both rate mode general flying as well as doing some acrobatics!

I will try and get one today...though my flie is in a terrible state

EDIT: Unfortunately due to the fact I have previously snapped an arm off my flie doesn't recover at all from the flips that well anymore, I need thinner carbon fiber tubing to make the arm sturdier, currently it has tubing that is slightly too big and so the hot glue is taking a lot of the strain and is a bit flexible (which I think is affecting the flight). I wish I had recorded it before I decided to plough it hard into the ground (Bad workman always blames his tools )

Here is the video of me attempting flipping, sorry for the poor quality etc, I will try and do a better one once my CrazyFlie is in better shape. It used to recover much better from flips before the arm snapped

http://www.youtube.com/watch?v=D8LAUsW537k

After about 30 attempts, these were the only 2 "good" ones!!!

Pretty awesome! You are the first making a successful flip that we are aware of, congrats!

As you pointed out the Crazyflie isn't really strong enough to handle high speed crashes which flipping can result in. Some clever reinforcement might do the trick. I've tested to tie a fishing line between the arms with good success. It is light and easy to come by but a bit difficult to tie well...

Just dusting off an old topic here:

Is anyone still attempting this? Or has programmed this? I also just started testing with flipping and got some promising results after just one evening of editing the pc client (even though it was my first day programming in python). I think the crazyflie can do some pretty smooth and consistent flips with the right programming!

I made a new controller button. The only thing it does it temporarily raise the max roll angle to 600 (but any number over 300 will do I guess). When pressing it and throwing the thumb-stick to the side, it'll stop one rotor and put the opposite one on full. It's really difficult with timing, but I got two or three flips very smooth and got it stable again right after the flip. Let's forget about the 30 tries that ended in crashes...
The trick is to throw it up full throttle to get some upwards momentum, then reducing the throttle to about 30-40% and throwing it sideways (with my flip-button pressed). At about 3/4 of the rotation, I let go of the flip button and hit the throttle to stabilize. The throttle slew-limit needs to be on 0 to make it go back to 30-40% fast enough. Otherwise it'll fly itself to the ground.

I'm planning to move some logic to the embedded side and try to completely automate the flip, including throttle and steering. Any advise on how this should be implemented is welcome!

For anyone who also finds this cool, here is a short video showing some flips... made on a typical Friday afternoon at the office

https://www.youtube.com/watch?v=vtkUCm8bWCg

Very easy to implement and quite fun and reliable! All flips in the clip are performed after each other; I didn't have to cut out any fails. I even got a double flip working a few times, though it doesn't quite flip fast enough to get this stable.

I hope to work on coding some flipping intelligence on the crazyflie itself in the next few weeks. Will post the results if anyone is interested in it.