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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Virtual Flybar - what would you like to have?
11-24-2006 10:59 PM  11 years agoPost 41
Laurens

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Oegstgeest, NL

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Great thread Colin!

Ok here is my wishlist:

- (relativly) Affordable for students.
I'm just 19 years old and I love this kind of innovations

- Easy to set up at the field
I want to go out to fly, not to tune the small things everytime. When I'm entering a constest my stuff should work properly.

Edge rotorblades, Scorpion systems

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11-24-2006 11:15 PM  11 years agoPost 42
Yug

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AirWolfRC - I pondered the idea of a piezo element built into the blades, but after speaking to several piezo element manufacturers, it was felt that physical deviation and robustness may well not be upto the task, a great shame as I am very pro the idea. One other aspect of this that I wasn't too happy about was the fact that most pilots have a preference to particular blades which would put quite alot of pressure on the right blade design and it's incorporation of the bender elements. This is why I'm preferring the actuator to exist within the hub/grips. Piezo torsional benders are an obvious choice as they have the speed and repeatability but finding the right piezo configuration either as a stack, bender or helix is still very tricky as we are looking at a total of about 40 degrees of movement which tends to go beyond the physical capabilities of a device small enough to fit on a hub.

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11-24-2006 11:23 PM  11 years agoPost 43
AirWolfRC

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42½ N, 83½ W

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Piezo is not the only answer.
http://www.newscientist.com/article.ns?id=dn8288
http://www.sbir.nasa.gov/SBIR/succe.../9-066text.html

The advantage of this type of pitch actuation is the inherent variable pitch from root to tip giving much greater rotor disk efficiency.

Should my idea take a decade or two to materialize, it will have company in the wait

Wolfgang

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11-24-2006 11:31 PM  11 years agoPost 44
Yug

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UK. Herts

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Yep, I've always liked the idea of some sort of polymer muscle wire but I reckon the technology is a long way off.
I agree with you about the bender being incorporated within the blade, but it may well make the blades too expensive to be commercially viable - they get so easily broken in a crash.

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11-25-2006 03:32 AM  11 years agoPost 45
Eco8gator

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Palm Beach, FL

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Hello All

I’ve designed a roll/pitch stabilizer that I planned on doing almost exactly what Colin (and AirWolfRC) being proposed (done using COTS items) here. I’m already using the stabilizer on one of my labs micro air vehicles with a 6in wing span and it seems to work pretty well (makes a fast twitchy plane almost seem like a trainer in the air). I know its not a helicopter but I had to make sure the system worked on something that I could crash and not break The price for the expensive IC's (3 axis accelerometer, 2 axis gyro, and microcontroller) was just a bit over 100 bucks.

As of now my program features (the programming was tailored to my small aircraft but is easily changed)

*5 PWM inputs from any Rx
*3 Outputs (for std mix, CCPM, or up to a 3 control surface plane)
*roll and pitch angle limits
*command of roll and pitch angle set point (judged from a center that is "grabbed" during initialization). The aircraft should stabilize around these set points.
*Input for a future sensors via I2C port (notably a compass but possibly a new senor package with a microcontroller that sends all the new data via I2C to the main microcontroller)

I’m going to read more about the V Bar system to see how much code I’ll have to add, or possibly completely rewrite. But I am very interested in this subject because I like having as few mechanical parts as possible.

For my current system Im thinking about trying something on the TREX SE. For bigger helis Ill defintally need to remake the board to support higher currents but thats not too hard.

Carlo

And to answer the question.

*Id like a much cheaper system than 800 bucks

*I would like it to be an all in one sensor package and mixer

*Easy to use software with templates for different models that your pilots have used

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11-25-2006 05:02 AM  11 years agoPost 46
Islander

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San Jose, CA

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i did the same thing with futaba gyros
Hi,
i did a similar conversion for my raptor30 a couple of years ago. I first converted the head to be flybarless and then put two gy601 gyros for roll and pitch axis. It works somehow, but also it produces some bad effects, among them:
a. sensor drift is severe, as you know, heading lock employs PI control which has an integrator inside the controller. The engine vibration or sensor drift makes the trim off after a couple of minutes. So i was busy re-trimming the heli all the time.
b. when the heli is still on the ground, PI control can "wind up" the output and makes the servos to go to extremes. It takes some time to get used to.
c. if the rotor blade is "soft", the controller can sometimes go crazy midair in FF. A pair of fiberglass blades solved the problem.

so i was not satisfied with that experiemntal stuff. I am planning to build my own 3 axis gyro + 3 axis accelerometer units, which might be better programmed to suit the thing.

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11-25-2006 07:12 AM  11 years agoPost 47
Colin Mill

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England

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Hi Laurens
Affordable for students. I'm just 19 years old
Well, as for cost it has been our policy, despite being a small company, to try to force prices down. When we brought out the 360 gyro - the first with heading lock - it was, at £130, less than half the price of the JR3000 gyro that had been the previous front-runner in the gyro field. We also came into the governor market with the RL10 below the price of the competition. So, we will certainly try to keep e-flybar as cheap as possible.
- Easy to set up at the field I want to go out to fly, not to tune the small things everytime. When I'm entering a constest my stuff should work properly.
From what we know now about e-flybar systems it is fairly easy to get handling that matches conventional flybar systems. When compared with the tail systems on most helicopters the cyclic commands are not exactly what you would call crisp! However, I believe that this technology will be used by competitively minded pilots to wring out the last ounce of performance from their machine and to tailor the dynamics in a way that is simply not possible with mechanical systems. Between the mixer and the gyros there will be something like 60 parameters. I make no apology for this - any technically advanced sport will require this level of complexity (look at F1 for example) and those that will win will be those that get to grips with this.

Hi Islander

Unfortunately the mix of control terms (HL, conventional, acceleration, direct, etc) required for control of the cyclics is completely different to that required on the tail. For a start the natural damping of the cyclics is far higher than that of the tail. This means you simply can't get very far with a gyro where you don't have complete control over that mix. As for drift, the best that can be achieved with sensors that fit price-wise into the RC market is around 5 degrees per minute - small compared to the imperfections of a mechanical flybar which has no long-term directional stability so for a vehicle that is being piloted this is entirely satisfactory.

Colin

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11-25-2006 08:28 AM  11 years agoPost 48
Colin Mill

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England

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Hi Carlo
*Id like a much cheaper system than 800 bucks

*I would like it to be an all in one sensor package and mixer

*Easy to use software with templates for different models that your pilots have used
Long-term I think all this is possible - the price does depend on the sensors coming down. Accelerometers, which are a closely related technology, have come down about 30 fold in recent years and per axis are only about a tenth of the price of a gyro so I have hope that gyros will become cheaper as the volumes used in automotive applications rises.

The templates etc will come. Obviously, the range of options available to the user (RC system, servo types, linkage geometry, teeter stiffness, head rpm etc) will make this an interesting problem!

Colin

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11-25-2006 09:45 AM  11 years agoPost 49
Islander

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San Jose, CA

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Hi Colin,
how about velovity drift? The drift you were talking about (5 deg/min) is "angular drift", i.e. drift after integral of angular velocity. do you find the sensor to drift after some time of operation (deg/min^2)? for example, the output of the sensor (angular velocity) drifts after a couple of minutes (so the gyro thinks itself rotating, but it's not, so it rotates the heli instead). I found this perticularly severe when it's on a .90 machine where vibration is orders worse.

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11-25-2006 10:38 AM  11 years agoPost 50
Colin Mill

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England

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Hi Islander

We have spent some time looking into the vibrational precession problem you describe. I posted something about its origins on:-

http://www.runryder.com/t195487p1/

As the effect is not due to a defect in the sensors but simply a matter of the physics of the situation suitable vibration isolation is the key to reducing the problem and the AV mount supplied with the SL720 gyro is the result of this work and in conjunction with careful siting of the gyro generally reduces the vibrational precession effects the same order as the inherent drift of the sensors. Of course the mechanical flybar has no long-term angular stability - it simply precesses towards the control plane (the plane of the swashplate) with a following rate of a fraction of a second. Using heading lock decay in the gyro has the same effect for the electronic flybar (and would mask drift). It also helps to keep the swashplate centred when the heli is on the ground. However, heading lock decay also allows the natural pitch up stability of the helicopter in forward flight to 'come through' so long HL decay times help make the heli 'groove' in fast forward flight.

My feeling is that e-flybar systems will have an effect on the handling characteristics of the cyclics as profound as Heading Lock had on the tail and that flying styles will evolve to exploit the advantages and accommodate the difficulties. Heading lock caused endless problems with people taking off with full tail pitch on (and even stabbing the boom with the tail blades as they spooled up in the folded position) but you don't hear of those problems now as pilots avoid them. So I think people will use short HL decay times initially because it gives more of a conventional feel but will want the advantages of long HL times in future.

Colin

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11-25-2006 04:35 PM  11 years agoPost 51
Laurens

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Oegstgeest, NL

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I'll definatly look into getting one once its available. Mods to the head won't be too hard I think.

Edge rotorblades, Scorpion systems

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11-25-2006 06:34 PM  11 years agoPost 52
stickyfox

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Rochester, NY - US

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does it work on the mac?

-fox

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11-25-2006 06:41 PM  11 years agoPost 53
Colin Mill

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England

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does it work on the mac?
What's one of those?

Thinking about it the USB interface and Win XP applications should run OK on a Mac.

Colin

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11-25-2006 06:49 PM  11 years agoPost 54
stickyfox

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Rochester, NY - US

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Well, if I could ask for anything, os x support would be it.

-fox

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11-25-2006 06:56 PM  11 years agoPost 55
nivlek

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Norfolk England

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Colin ,
With a pair of 720 gyros on cyclic, will I need to use high speed Digitals , or will standard speed Digitals be good enough ?

At the end of the day , it gets dark .

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11-25-2006 07:14 PM  11 years agoPost 56
Colin Mill

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England

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Hi nivlek

Very good question. I'm sure that if we are trying to push the gain of the system to the limit to get the tightest control over the handling than the faster the servos the better. However, our initial tests suggest that some very good results can be obtained without pushing the gain all that far. I would certainly go with your existing servos to start with.

Colin

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11-28-2006 02:35 PM  11 years agoPost 57
IYKIST

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London united kingdom

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Colin could this item be further developed to become a copilot or is a flight stabilisation unit in the works as well.

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11-28-2006 05:08 PM  11 years agoPost 58
Colin Mill

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England

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Hi IYKIST

Well, my main aim (the thing I get a buzz out of) is to provide systems for the dedicated contest pilot. My desire in this development is to come up with something that is dynamically more accurate than the mechanical flybar. I would very much like to 'stir things up' a bit - perhaps change the handling characteristics of the heli in as profound a way as HL did for the tail. If you compare almost any heli with a well set up fixed wing pattern ship the handling of the heli is nothing like as crisp and accurate. To close that handling gap would make me happy.

Although I have played about with various autopilot systems (mainly fixed wing as it happens) I have no short-term plans to enter that area of the market.

Colin (CSM)

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11-28-2006 05:46 PM  11 years agoPost 59
Carey Shurley

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Orlando, FL - USA

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suggestion
I didn't see this suggested anywhere in the forum and you did ask for suggestions:

support "flight modes" for the flybar setup. Be able to switch between previously configured flybarsetups from the transmitter. At least 2, maybe 3.

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11-28-2006 06:22 PM  11 years agoPost 60
Colin Mill

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England

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Hi carey

Many thanks for mentioning modes - I had quite forgotten to mention what I have in mind here. As luck would have it the SL720 gyro has two flight modes so mode switching is possible. At the moment (though there is some variation of opinion amongst the test pilots it must be said!) I feel that flight mode 0 would be used for take-off and hover. This mode would have a high rate of heading lock decay allowing the swashplate to centre rapidly once the cyclic stick is centred (good for avoiding taking of with full back cyclic applied!) and for allowing natural pendulum stability to make the hovering easy. The gyros have independent stick feel for each mode so I guess a reduced stick sensitivity would also be good. Mode 1 for aerobatics would have longer HL decay (perhaps no decay) to resist ballooning in fast flight.

A single aux channel could provide both mode switching and gain adjustment for both gyros via a Y lead. This would take the channel count for a heli with governor to 8. Nine channels would allow independent mode/gain control for the two cyclic gyros if desired.

Colin

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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Virtual Flybar - what would you like to have?
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