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HelicopterMain Discussion › HH gyros on aileron and elevator...
01-24-2007 06:02 PM  10 years agoPost 1
QuantumPSI

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Atlanta, GA

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Hey everyone,

I'm working on a research project with a Trex fitted with some fancy equipment and we need it to be stable enough such that it stays level without any input. We will use control loops to handle the drifting but right now, we want orientation to be maintained. We currently have piezo gyros on the cyclic controls and they simply aren't good enough. We need it to take off perfectly level and stay level and thus we are thinking about fitting it with 2 GY401s. I did some searching here on RR and found this thread...

http://runryder.com/helicopter/t497...HH+gyros+cyclic

However, I couldn't find any information to find out if anyone has actually done it yet. PLEASE DO NOT TELL ME WHY IT WILL OR WILL NOT WORK IF YOU HAVEN'T TRIED IT YOURSELF! We need to know if it will work from people who have tried it. We believe it will work and just want to hear from someone who has tried it successfully or unsuccessfully. Thank you!

Mikel

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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01-24-2007 06:51 PM  10 years agoPost 2
BarracudaHockey

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Jacksonville FL

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If the heli is perfectly level it will work, if its anything but it will fly off in exactly the orientation it was in where you left it.

I'd reccomend not doing it as heading hold gyros dont have a ground or level reference like the auto pilot products do. Its the same reason the aeroplane guys that try them put them in rate mode to fly around and only use heading hold when trying to torque roll.

Andy
AMA 77227
http://www.jaxrc.com

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01-24-2007 06:53 PM  10 years agoPost 3
MrMel

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Gotland

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Havent tested it on a heli (I know your statement), but Ive tested it in another application, I had problem with "center" moved, so the gyro thought it was level but it was not, you needed to reset the gyro once in a while.

I guess thats why all pre-built applications doing that work need other sensors...

http://www.spartan-rc.com/products/ap2000i/ap2000i.htm

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01-24-2007 07:02 PM  10 years agoPost 4
AirWolfRC

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42½ N, 83½ W

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Well, I guess you're going to have to keep doing research because no one will be able to hand you the answer on a platter.

The answer is not that simple. If you ever get there, you'll know.

Gyros will drift and they won't know that they are drifting, so they can't correct themselves (and the heli).

Holding a stationary position in space is not feasable without something like GPS or some other ground based position reference, period.

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01-24-2007 07:03 PM  10 years agoPost 5
3D Heli Ireland

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Ireland

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Check out this link http://runryder.com/helicopter/t303432p1/ to my CSM flybarless testing. Although my machine has had the flybar removed the principle will remain the same.

From my findings with the CSM system I would say you are going to have great difficulty getting the system to work, just as you want it to, with 401's. In my opinion and experience you simply will not be able to adjust their fundamental method of working sufficiently to get the desired result. It's worth a try though.... Going down the CSM route will eliminate alot of your immediate headaches.

Skookum Robotics,Sav�x, Motors and Servos,Optipower,SwitchGlo,CML st

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01-24-2007 08:42 PM  10 years agoPost 6
kangarooster

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Orlando Fl-USA

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Didn't work.

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01-24-2007 08:48 PM  10 years agoPost 7
chopperman1

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Huntsville, AL

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It would be cheaper to use the stablizer system from fmadirect.com. Right?

Cliff

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01-24-2007 08:54 PM  10 years agoPost 8
3D Heli Ireland

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Ireland

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Hmm...don't know,seems to work for me, anyway you can catch it a page or two back on the main discussion.......

Skookum Robotics,Sav�x, Motors and Servos,Optipower,SwitchGlo,CML st

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01-24-2007 09:01 PM  10 years agoPost 9
kangarooster

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Orlando Fl-USA

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I meant that the 401's on my Trex didn't work.

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01-24-2007 09:02 PM  10 years agoPost 10
3D Heli Ireland

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Ireland

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Ahhhh sorry......I'm just a dumbass....forget that last post

Skookum Robotics,Sav�x, Motors and Servos,Optipower,SwitchGlo,CML st

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01-24-2007 09:08 PM  10 years agoPost 11
kangarooster

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Orlando Fl-USA

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No problem. My first post wasn't clear.
I think the CSM system might be the answer.
My 5 bladed flybar head has been giving me a few problems.

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01-24-2007 09:13 PM  10 years agoPost 12
Angelos

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nr Oxford, OX11, UK

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QuantumPSI,
I assume you want automated flight in which case these will apply:

1. No heading hold gyro can indefinitely hold a helicopter in hover. The drift may be minimal but within seconds it will build up enough to disturb a perfect hover and it will continuously get worst.

2. The way heading hold gyros work is not suitable for your needs.

i) If you mix the your position control with the gyro output; then the gyro will oppose everything you try to do.

ii) If you put your position control before the gyro the helicopter will not return to level when your position control signal returns to neutral. Instead it will maintain the new titled angle. To get the heli back to hover you will need to give it the exact same but opposite control. However, due to pulse generation and sampling quantization errors within a few corrections the angle will no longer be what you think it is.

-Angelos

Spartan RC R&D

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01-24-2007 09:16 PM  10 years agoPost 13
Peter Wales

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Orlando Fl

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Isn't the Trex Eccpm? If so, you wont be simply putting a gyro on each of the cyclics

Peter Wales
http://scalehelicopters.org

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01-24-2007 09:25 PM  10 years agoPost 14
BarracudaHockey

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Jacksonville FL

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Depends on which version on the Trex but thats true, a ccpm machine uses the pitch servo to control the swash so that would make the whole argument moot.

Andy
AMA 77227
http://www.jaxrc.com

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01-24-2007 11:40 PM  10 years agoPost 15
sharam

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Northern California - Fly at Morgan Hill Field

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The best/cheapest way to stabilize the heli is with the FMA co-pilot. I had one installed on my Nexus and I could get it to just sit there in hover for quite a while, hands off. It did have to be calibrated properly.

I tried the GY352 dual axis on cyclic and had no luck. FMA worked much better.

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01-24-2007 11:49 PM  10 years agoPost 16
AirWolfRC

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42½ N, 83½ W

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The FMA CoPilot WILL have a better chance of doing a (reasonably) stable hover. It uses the infrared horizon as a refernece.

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01-24-2007 11:49 PM  10 years agoPost 17
hammerondown

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Chattanooga,TN USA

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http://www.rcmarket.org/Auto-Pilots-p-1-c-141.html

Robbe's answer

R50,HYPER50,GY401,TJPro,DX7

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01-25-2007 12:33 AM  10 years agoPost 18
QuantumPSI

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Atlanta, GA

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The helicopter will be flown indoors and thus the FMA copilot is not a viable solution.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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01-25-2007 01:05 AM  10 years agoPost 19
Yug

rrMaster

UK. Herts

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For doing this outdoors, you'll need several systems if you want it to remain completely stable and in one position. The fact that you say you will be flying it indoors makes the job nice and simple - use ultrasonic transducers to recover absolute positional information. In simple terms, the heli has an ultrasonic emitter or 3 which generate a burst signal coherently. 4 or more ultrasonic receivers can then be situated around the hall, perhaps one in each corner. The relative time differences between each of the receiveres receiving the pulse signal can then be used to mathematically calculate the absolute position of the heli. This method will be much easier to implement than perhaps and rf triangulated system.
Whatever the deviation detected can be used to tx back to the heli in order to correct with the appropriate PID type algorithm. The heli would therefore require no extra electronics than a normal heli, with the exception of a simple micro and 3 or 4 ultrasonic emitters to provide a spherical(ish) radiation pattern from the heli.

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01-25-2007 02:25 AM  10 years agoPost 20
tchavei

rrProfessor

Portugal

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I'm with hammerondown. Robbe helicommand is the answer. It has a camera pointing down so that it not only keeps the heli level, it will keep it on the same place. Only catch seems to be the camera not beeing high resolution to be able to work at high altitudes but a friend of mine has it and its able to keep the heli within a one inch box at 3 feet height.

Tony


--------------------
"Perfection and patience usually walk side by side..."

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