Custom gyro and building, need help.

[xzavin]

Hey, I am planning on building a fairly complex flying vehicle, it uses four ducted fans to hover and a fifth to propell it forward, this obviously isn't the most stable thing in the world so I need help building a custom gyro that fits my needs, I was thinking, take a small tube a bit larger than a marble, take a marble and put it inside, on either side put buttons that turn on when touched and off when not touched, anyways there would be just enough resitance in the middle so that the ball wouldn't just roll around, but how can I make it so when a button is pressed it increases the throttle to that motor by like 10% because I don't want it to flip due to too much power. Thanks guys, and by the way I was going to use 2 of these things, one for side to side movements and the other for front to back movements, so any tips on making it work would be appreciated.

[Erez-E]

Why do you need a custom gyro for this? Normal rate and heading hold gyros work just fine connected to an ESC and motor.

[xzavin]

Really? But wouldn't I need one for each motor?

[Erez-E]

Yes, but you can get them now for $15 each. Or you could use a good quality mixer. If you want attitude hold then mixers are a better way to go.

[xzavin]

Alright, I need to stabalize four ducted fans, can somebody point me to where I can get a system that lets me do this for under 200 dollars please?

[cstratton]

You almost certainly can't do it for that price by the time you've actually gotten it working, unless you are duplicating someone's already proven project using their final shopping list, and even then it's chancy.

But for the first cut maybe try to find gryo/mixer combos intended for coax helis. Normally these would control yaw by getting more torque out of the upper or lower rotor. But maybe you could mount it to control roll by making more thrust on the left or right motor. Then have a second one doing fore/aft.

Problem is most of the cheaply available ones are integrated with the receiver... and then you'd end up with two radio systems, one controlling pitch and the other controlling roll!

You should probably read the quad rotor threads, because that's basically what you've got, only ducted. Worry about the pusher motor later... though you may not even need it.

[xzavin]

I will need it, Moller makes the actual skycar, they can't get it to fly straight....they aren't using a 5th motor but with the 4 they cant move forward without crashing....

[Brandano]

you only need two gyros, and only need them on two motors. one to control pitch and one to control roll. Incidentally, the marble device you were depicting won't work, because it will be tripped by linear accelerations too. It's easier to think about the 4 fans as if they were in a cross shape, a couple controlling the pitch and the other controlling the roll (easier to mix too, btw). Set the gyros so that one of the motors for each couple is affected by it. You don't need to put the signal on both motors, though it will affect the altitude hold. Now rotate the whole thing by 45 degrees and you are set.

[xzavin]

Would two gyros and minimixer or whatever is on the VTOL forum work? I will get a link but its a 79.00 mixer....just looked at it, he uses it on his VTOL with four motors....I might ask him for help....

heres that link

http://www.rcgroups.com/forums/showthread.php?t=949507