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Old Dec 18, 2012, 11:41 AM
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2501,

Seasons greetings.

If I were to go with a board, would you still be interested in helping set it up?

I'm wondering if it would be easiest to have a servo per foil (4).

I would need automatic control in 1) ride height (altitude), 2) roll, & 3) pitch.

The only manual input would be yaw.
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Old Dec 18, 2012, 01:37 PM
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Are you still trying to solve this with a gyro? If not, look down in the first post for videos on Arduino and MultiWii. They should give you an idea of what you can do with a board: http://www.rcgroups.com/forums/showthread.php?t=1668441
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Old Dec 18, 2012, 03:41 PM
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The entire purpose of accelerometers is to maintain stability based on a value established when you allow the board to initialize. If your craft deviates from those values it will react. That board also has a 3 axis gyro, a barometer and magnetometer. So the control functions you can use are quite extensive and very versatile. A gyro has very limited input/output capabilites, this board has many. These boards are used to stabilize and control most aerial camera platforms you see now. I'm pretty sure it will handle your needs. They aren't that hard to program. All that is required is picking limits in a GUI program. However, if this is beyond what skills you feel you have, a KK2 board is about as difficult as setting an alarm clock. http://www.hobbyking.com/hobbyking/s...rol_Board.html
Why do you ask "are you still trying to solve this with a gyro"?

It would seem a board is the way to go, don't you think?

Four foils independantly controlled would seem to make sense to me.
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Old Dec 18, 2012, 05:25 PM
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It seemed like the last page or two were more gyro related and I didn't want to be pushy. Don't take this personally as it may not apply, but most of the time when people come here looking for advise, they are looking for affirmation of ideas or plans that fit their comfort zone. Using a flight control board for stabilization of some other craft is pretty far outside the box for lots of people, as you can see by the general flow of this thread. There's always the possibility they are right and I'm full of crap.
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Old Dec 18, 2012, 07:30 PM
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Originally Posted by Balr14 View Post
It seemed like the last page or two were more gyro related and I didn't want to be pushy. Don't take this personally as it may not apply, but most of the time when people come here looking for advise, they are looking for affirmation of ideas or plans that fit their comfort zone. Using a flight control board for stabilization of some other craft is pretty far outside the box for lots of people, as you can see by the general flow of this thread. There's always the possibility they are right and I'm full of crap.
Sometimes the journey involves many wrong turns but it's so much more interesting that way. Active stabilization in multiple axes is extremely tricky even when you're dealing with "solved" aircraft like a quadcopter. So I was discussing the option of stabilizing only one axis actively and letting the fins do the work for the rest. I supposed that this might give a more natural feeling movement, but I also strongly urged to test that long string of assumptions.

You are absolutely correct though I think... to stabilize in multiple axes, you'll need more than gyros, you need a board with at least three axis gyro and the ability to program it so you can generate control surface positions for all axes to work together, like on a quad copter.
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Old Dec 18, 2012, 07:56 PM
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Lol!

Well, it is pretty outside the box.

I think it's called pioneering.

I really need some help here as you guys know more about this than me by a long shot.

I appreciate the sentiments but lets stay focused.

Can you help me get a board up and running?
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Old Dec 18, 2012, 09:14 PM
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I'm not an expert with those boards, so "maybe" is the best answer I can give you. However, there are lots of experts here: http://www.rcgroups.com/multirotor-electronics-792/
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Old Dec 19, 2012, 10:49 AM
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Originally Posted by BluenosePacific View Post
Can you help me get a board up and running?
For a quad copter, yeah, but this might not even work. We can pretty safely assume that control loops designed for air aren't going to work well in water, that's why we're pushing programmable boards. But here's the thing - I suspect that to make it work in water, you'll need more than a settings adjustment, I think you're going to need completely new software. We're making a lot of assumptions, and to turn those into known things, some testing is in order. We don't even know if this is possible - potentially, water is 'too slow' to function with active stabilization.

Active stabilization requires that a control input produces a change in vehicle attitude quickly, because the gyro 'waits' until a small amount of error is generated before it does anything about it. I'm betting that water is too slow and too variable for that to work, and if that's the case, you're going to need some kind of predictive algorithm. It's possible you may need to feed in more than gyro input to stay stable. Such as, you may need to feed in the positions of the wands as well. If you want this system to maintain ride height, you're going to need accelerometers to measure changes in height as instantly as possible. Since the existing boards are mostly designed to fly quad copters, you're going to need to customize it somehow to make it work in water, and I think that customization will exceed the user-configurable options of existing boards. However if they are based on Arduino, you'll be able to do that - you will be limited by the available sensors though, and it's sounding like you may need a "six axis" type, which measures rotation AND translation.
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Old Dec 19, 2012, 01:17 PM
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Yes, 2501, an Arduino board of course, perhaps the Mega2560 as it's PWM compatable.

I would love to get rid of the mechanical surface sensing wands.

They are added weight and vulnerable.

You know, water at low speed is very similar to air at higher speed...
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Old Dec 20, 2012, 11:06 PM
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Would the Mega 2560 be a good candidate for a board?
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Old Dec 21, 2012, 10:21 PM
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Would the Mega 2560 be a good candidate for a board?
No way to know really without testing, do you have a link?
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Old Dec 23, 2012, 11:43 AM
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No link, but it looks appropriate.

Thanks for all your help gang, Merry Christmas.
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Old Dec 23, 2012, 12:35 PM
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No link, but it looks appropriate.

Thanks for all your help gang, Merry Christmas.
I was on my phone yesterday and being lazy, but I'm glad I looked it up...
http://arduino.cc/en/Main/arduinoBoardMega2560

According to that description, it doesn't have any sensors - so you would have to buy gyros and learn how to hook them up. It's a 'dumb' board - no sensors, no software. Those are very general-purpose. You could make anything from it - from a quad copter to a home security system. I think you should start with a board designed for stabilizing an aircraft, and tweak it for watercraft - that way you have a starting point with some of the problems already solved. That's why I suggested Ardupilot - which is apparently discontinued and now they have more specialized stuff. This one is designed for a quad copter - http://code.google.com/p/arducopter/wiki/ArduCopter

However, look at these quotes from the page...
Quote:
Read the manual! ArduCopter is a flying robot, not just a RC copter. It's much more powerful, but also more complex. Reading the manual before flying will pay dividends.

Experience with other planes or stabilized single rotor helis is highly recommended. ArduCopter is not a RC toy and should not be your first RC aircraft.

ArduCopter is an open source UAV, created by a large and active development team. As such, it is constantly improving and the software is upgraded frequently. If constant innovation and frequent addition of new features appeals to you,

ArduCopter is a good choice. If, however, you don't want to upgrade often and or learn new features, a closed-source multicopter may be a better choice for you.
Safety first! Read this before you spin up your motors or fly.
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