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vidur
03-30-2005, 08:29 PM
Hello Robonauts

I bet many of you would someday love to build a UAV, but obviously it takes a lot of skill & finances to build one...

I put up this thread if we could discuss what would a UAV take to build...what all components its controls should be built around, discussions on aerodynamics, communications, helicopter type or airplane type, electric or engine powered, propulsion, weight problems , body design & other design considerations.

As far a i'm considered i'm completely clueless on this one....we can have a very good discussion on this & hopefully this could become a very good resource.


To start up, I think making a Helicopter type design would be easier & less risky to fly. Making propeller & rudder control will probably be the biggest problems to solve...considering most of us live in India!


Please put in your dream UAV design ideas or anything else related on this thread

Vidur

vikas
03-30-2005, 09:31 PM
Well its one of mr dreams too :) . Here is what i think is feasable on a shoe string budget ( abt 30 k ) ..

A Plane based UAV i think will be much easier ... cause the flight dynamics is much easier . A helicopter is not that easy to manover ( Try to play around with a toy RC Helicopter and ull understand ) . ( 200 $ + for a decent plane ) . Ill prefer engine powered ... batteries dont last long for achiveing decent flight times .

Communication ... This will depend on the range and and amount of data u want sent back . For me i think a survelence type vehicle with GPS as tracking system and small cheap cam as the survelence cam should do the job ( 80 $ : GPS , 50 $ camera ) making it autonomus yet usable . Can use a cheap FM type of transmitter for sending back very basic data ( 20 $ + ) .

Weight problem ... damn havnt built one so cant say . Anyhow goin for IC based engine will save dead battery weight and u can power the uC and other things using light lithium batteries .

Body and design considerations : Hmm ill be better of buyin a RC plane and modding it cause i dont know shit abt flight dynamics .

BTW : Check bazee for cheap RC planes ( start arnd Rs 1500 ) ... but they are too small for anything similar .

Hmm still to build one but so little time and not a small weekend project :) .

Anyhow check this one http://www.hobbytron.com/Dragan-Fly-4-deal.html
saw it on discovery and looked damn cool .

vidur
03-31-2005, 10:00 AM
Dont you think fuel cells would give an advantage over both engines & batteries?

I think a fuel cell would cost less than a engine!

In the radio, ordinary modules cant be used, the system may experience doppler shift & some amount of auto-carrier signal control may be required

As far a flight dynamics are concerned

3 controls

flaps/ailerons--makes the plane plane tilt left or right
stablizers---pitch control i.e up or down
Rudders--direction control- for moving left or right

This is probably where chopppers can do with 2 simple to implement controls........or for starters we can use multiple motors for direction control as submersibles do


say...one main rotor for lift
two small auxiliary motors for directional thrust....

But i aint got a clue how to get the blades fabricated

Vidur

sid_galt
03-31-2005, 10:59 AM
What system could I use for measuring pitch and roll. I was thinking of a box filled with water or any other material and dynamic pressure sensors placed at each end to measure the pressure change and tell me the incline. Or would gyroscopes be better and smaller?

For communications, could one use a cellphone type system? Using a cellphone radio, card and a home programmed chip instead of a digital to analog converter? Or would the chip be impossibly difficult to program?

vidur
03-31-2005, 12:19 PM
You'll add up instability if you use a box of water....

too much slosh & the UAV spins out of control...

Gyros are a good option...but it may not be the best...lemme pnder on

this one

Vidur

subot_robot
03-31-2005, 12:22 PM
Hi,

For communications, could one use a cellphone type system?

Yes, for communication between UAV and computer we can use cell phone, for example reliance which offer i high speed internet on cell phone.
For measuring pitch and roll you have number of options.
u can use on chip gyroscope from Ananog devices or
kMZ51/KMZ52 magnetic sensor IC, from philips, placed in some configuration (3 kMZ51 chips mutually perpendicular to each other will give variation along x,y and z axis.
I don't know if accelerometers can also be used for this purpose.

subot_robot

vidur
03-31-2005, 07:38 PM
I dont think we can use accelerometers...coz they cant tell an upside down vehicle from an upright one.

I guess we've got gyros as the best option so far...i havent used any till now....has anybody have any experience with them

one gyro = 3 magnetic sensors....so gyros win! :-)

or you can prove me rong!

vidur
03-31-2005, 08:02 PM
Vikas

I saw the dragon flyer...but looking at it..i cant see how it achieves directional control....i.e we can see it can move up or down...but what about fwd, back left or right?

The helicopter rotors dont seem to have any pivots....atleast i cant make out any from the picture..

only one thing is odd....3 blades are colored red........one is yellow

any guesses why?


vidur

vikas
03-31-2005, 08:35 PM
Water based :) ... nice one What if my water evaporates ??? Jokin Anyway itll be hell of a unstable .

Gyro based solution is wat is required . Fuel cells ??? They are too damn heavy for the power they provide :) . Reliance based communication .... Too damn heavy and expensive e ( Ull end up spending most of ur money on reliace bills :) ) ... There are GSM cellular modules availible which do this in a better way like the GM862 series ( http://www.sparkfun.com/shop/index.php?shop=1&cat=75 ) . For the dragon flyer it works like a normal helicopter see it flight control details http://www.hobbytron.net/media/draganflyer3back.pdf . Check out videos at http://www.rctoys.com/videos.php .

Hmm this makes me think ... i should have one :) but at a price tag of 1 Grad USD its too damn expensive ... maybe build my own 8) .

sid_galt
03-31-2005, 10:21 PM
Water based :) ... nice one What if my water evaporates ??? Jokin Anyway itll be hell of a unstable .

I didn't mean a huge box of water. Anyway it doesn't have to be water. If we take 1 g of any material and place it on 2 mm-square piece of material, which is placed on a piezoelectric sensor, the pressure difference for 1 degree change in incline comes out to be 0.0381 Pa.
Is a piezo sensor sensitive enough to register such a small change?



Reliance based communication .... Too damn heavy and expensive e ( Ull end up spending most of ur money on reliace bills Smile ) ...


I don't think so. What you need is a cellphone radio, cash/sim card and a microprocessor which you have to program. Batteries are already available onboard. It can't be that heavy.

As for expensive, with a bsnl mobile, incoming calls don't cost and you have ability for good long distance communication.

vidur
04-01-2005, 10:06 AM
the thing is using piezo sensors you can make an 3 axis accelerometer not something that tells you the spatial orientation of the craft

So has anybody worked with gyros?

sid_galt
04-01-2005, 11:01 AM
the thing is using piezo sensors you can make an 3 axis accelerometer not something that tells you the spatial orientation of the craft


What about piezoresistive pressure sensors? I think They can be used to measure static pressures by measuring the change in resistance. Can they be used?

vidur
04-01-2005, 06:02 PM
What about piezoresistive pressure sensors? I think They can be used to measure static pressures by measuring the change in resistance. Can they be used?

Your'e missing the point....how can change in pressures give you any info if your vehicle is upright or upside-down....

:roll:

however a gyro can....

sid_galt
04-01-2005, 08:33 PM
how can change in pressures give you any info if your vehicle is upright or upside-down


A lot of info I guess.

Imagine a cuboid of 1 gm of any material. Static pressure sensors with small effective area are placed on each of its faces. Any incline will change the amount of force being exerted on the sensor and hence the pressure. Hence you can measure the plane's incline around any axis except the yaw axis.

The only thing I do not know is whether gyroscopes will take less space and weigh lighter or this system.

subot_robot
04-01-2005, 09:52 PM
Hi,

one gyro = 3 magnetic sensors....so gyros win!

or you can prove me rong!

You are correct if u can get gyro easier and cheaper than maganetic sensor. Can u get variation in all 3 axis with 0.1 degree resolution in gyro? If yes, then u r definitly correct. I tried getting KMZ51 and KMZ52. But i could not get them here in India. So i bought a magnetic compass module from acroname.com which has 2 KMZ51 placed perpendicular to each other. May be we can try 2 such modules. But each magnetic compass module costs $50.


Reliance based communication .... Too damn heavy and expensive e ( Ull end up spending most of ur money on reliace bills )

You can pay a flat fee less than Rs.1000 per month and have unlimited internet access for reliance mobile. Regarding the weight, it will depend on the size and cargo capacity of the UAV. I think any cell phone is the best option when it comes to range covered, speed of data transfer and weight. If we get gsm modules which offer the same or better quality of service which is lighter and cheaper, then i agree with you.

subot_robot

vidur
04-02-2005, 01:16 PM
okay lets talk about fuselage & rotors or engine if we're talkinh bout' airplanes

what kind of materials to use for blades....metal(say Al),wood,carbon fiber fibreglass etc?

& navigation........autonomous or controlled?

sid_galt
04-16-2005, 12:19 AM
If the live video from the video camera is transmitted continuously to a computer where it is displayed, what configuration computer do you think will be able manage a smooth (greater than 25) frame rate?

vidur
04-16-2005, 09:28 AM
You can transmit 25 frames per sec without problems by trading off the camera's resolution....use a very low res camera & you'll save bandwidth!
Say a few kilo pixels.....try a cheap webcam or CCDs from a mobile phone!

sid_galt
04-16-2005, 11:54 AM
You can transmit 25 frames per sec without problems by trading off the camera's resolution....use a very low res camera & you'll save bandwidth!
Say a few kilo pixels.....try a cheap webcam or CCDs from a mobile phone!

So roughly what configuration should be my computer to be able to display the video. Would for e.g. a PIII work? The reason I'm asking this is because my PIII can't even handle flight simulator at medium settings, so I doubt it will be able to show streaming video at a good frame rate.

vidur
04-16-2005, 04:27 PM
The thing is Flight sim simulates true aircraft performance in real time thats why it struggles a lot. Remeber professional flight simulators use supercomputers for rendering graphics!

I suppose your P-3 would do fine with a low res CCD device

sid_galt
04-16-2005, 04:33 PM
I suppose your P-3 would do fine with a low res CCD device

Additionally what software do you think would be good for modelling and computing the airflow over the wing? Would matlab do fine?

What CPU configuration would you recommend for that?

vidur
04-16-2005, 07:17 PM
Oh yaaa....its a kick ass piece of software...I had tried my hand at airfoil simulation a long time ago.....

result.....airfoils tend to stall when angle of attack & velocity vector differ by around 25 degrees!
see if you get this result...i dont evn know if it is correct!

Vidur

04-19-2005, 04:12 PM
It is not a constant, the stall angle of attack varies based on airfoil. An airfoil with rounded leading edge will stall later than one with a sharp edge. Some planes use slats to delay the stall.

If you are building a plane, build the wing such that the wing tips stall later. Usual way to achieve this is to add washout to the wing.

vidur
04-19-2005, 06:42 PM
hey...the simulation i did was for a flat foil!

can you explain what makes a curved foil stall at a higher AoA?

vidur

sid_galt
04-20-2005, 07:47 PM
Alright, things look pretty bad for video transmission via cell phone for me.

Taking a 160x120 resolution and 10 frames/sec transmission rate, it comes to 562.5 KB/sec. Clearly no wireless transmission can handle this.

But there is another possibility. I have read somewhere on the Internet that MPEG-4 compression can give a compression ration of 100:1 which means the required transmission rate will reduce to just 5.6 KB/sec which is easily maneagable.

1) What I want to know is, what processor speed will be required so that the compression time doesn't exceed say 1/10 of a second? Would a 120 MHz speed be fine?

2) Using a regular cellphone will mean that I will have to convert the analog signal of the video camera to digital, compress it, convert it back to analog and transmit it to the cell phone chip? Does anybody know a digital card or something that can be used for digital transmission via cell networks and which can accept digital input instead of analog one.

3) If the compression methodology is fast enough, I would like to transmit the video through the Internet. Is there any way to transmit it directly from the cellphone/digital card to a home computer?

jediknight
05-22-2005, 06:41 AM
Hello all,

Nice topic you guys got here.

Building a basic UAV isn't cheap at all. For my next year college project, I've built one already.

I'm making a scaled down model of Tyro fitted with OS 46FP engine & a wireless camera. Camera's range is approx. 100 meters. The range the aircraft can fly is LOS (Line Of Sight).

Here's what one needs to get the project up in air: (All the prices quoted are approximate prices & are subject to change without notice).

Aeromodel : Rs. 4,000
Rx/Tx : Rs. 14,000
Engine : Rs. 6,500
Fuel : Rs. 100/liter
Wireless Cam : Rs. 2,000
----------------------------------
Total : Rs. 26,600
----------------------------------

P.S - This list doesn't list how one might be able to acquire images transmitted by the camera fitted on the aeromodel. For that, one needs one of those cheap, portable B/W television sets that run on 12V DC which might cost at the max Rs. 1,000 & the fuel charge mentioned is a recurring cost.

WARNING: Before you even try flying it, I strongly recommend you practice model flying on your PC using flight simulators such as "FMS" that allow connecting your Tx on your PC and/or at least get a trained model flyer to trim your aircraft for you & teach basics about flying.

vikas
05-22-2005, 11:27 AM
congrats on your acivement ... can we have some pictures ???

jediknight
05-23-2005, 03:08 AM
Hi Vikas,
I'm terribly sorry, we haven't conducted a formal photo-session of the aeromodel as of yet. But when we do, I'll most definately post the pics online & let you know.

I was also wondering if anybody could help me make a "robot", it's more of one of those R/C cars & less of robotics, but I need to make a few tweaks in it.

If you want, I can email you a graphical idea of what I've thought of making.

Regards,
JeDi.

happy_99
05-23-2005, 11:37 PM
For my next year college project, I've built one already.

I'm making a scaled down model of Tyro fitted with OS 46FP engine & a wireless camera. Camera's range is approx. 100 meters. The range the aircraft can fly is LOS (Line Of Sight).

jediknight, nice work friend, congrats !! I'd love to see the pics.

Regds

happy_99

jediknight
05-24-2005, 12:29 PM
Dear happy_99,

I'm terribly sorry I have got nothing to show as of now. Some things came up, unexpectedly.. The engine failed, on further probing into that matter we found out last week that the engine was tampered with by somebody when given for tuning. Last evening, we got our hands on a new engine which is 52, instead of 46 earlier. It doesn't fit the mount on the aircraft. We're trying to make things work here as of now. Once we take the test flight & get that baby up in the air, I'd be more than happy to share pics with you. But till then, you'll have to just bear with me...

Sorry.

Regards,

JeDi.

vikas
05-24-2005, 05:47 PM
... hope u solve ur problems soon and we have some cool pics :) .

Till then as the saying goes ....

May The Force Be With You

happy_99
05-24-2005, 11:24 PM
Hi jediknight,

Take your time, we'll wait :-). Hope everything goes fine.

Wishing you all the best !!

Regds

happy_99

jediknight
05-25-2005, 01:13 AM
Hello,

Thanks y'all... I'm seriously worried about the future of this project. I'm praying to god that this project gets up in the air ASAP.

Regards,

JeDi

ice
05-25-2005, 07:21 PM
I was also wondering if anybody could help me make a "robot", it's more of one of those R/C cars & less of robotics, but I need to make a few tweaks in it.


Maybe i can help you out here.
Dont know wht you want to do..but if it involves decoding the RX signals PWM to a microcontroller,ive done it...

By tweaks do you mean arlon/ele/flap mix?

Wish you luck...which TX do u use BTW?

jediknight
05-26-2005, 12:30 PM
Hello ice,

Would it be possible for you to PM me your email, so that I could send a small .gif file that illustrates what I'm thinking of making?.
Just for a basic overview as to what I'm thinking of making.... it's something similar to the Mars Rover. A playform mounted on multiple tyres. That platform contains a wireless camera, a 2-way radio for communication & a LASER pointer. The camera & LASER pointer can be moves simultaneously through the R/C.

Regards,

JeDi

jediknight
05-26-2005, 03:05 PM
Hi ice,

Looks like you're from Aamchi Mumbai too. IF that's okay with you, do send over your phone # probably your cell # so we could discuss this thing in a more detailed manner.

Regards,

JeDi

ice
05-26-2005, 08:15 PM
JeDi,
Guess wht..im into making the same stuff as you..i jst finished my platform..however the gearing has gone a bit awry..hmmm...
check your pm..
but i would love to keep a thread on RI,so that other people can follow it too..
bbye

jediknight
05-26-2005, 10:49 PM
Hello ice,

I don't mind continuing the thread on RI, but just that you get exactly what I am looking out for, it would be easy for both of us to understand if we talk on phone.... hope I made more sense this time! :lol: :lol:

Regards,
JeDi

vidur
06-01-2005, 08:27 PM
Hey guys

I had an idea....

For starters you could cannibalize a model flyer thay you get on ebay for Rs 1300/-, add a small transmitter-receiver & probably transmit some data like temperature. it'll be a small project within everyone's reach

what do u think

Vidur

jediknight
06-02-2005, 03:20 PM
Hello Vidur,

Nice option, but did you know the model flyers you're talking about are Electric flyers? No matter what you use it as, it's still a T O Y!

They don't give you much control. & the Tx provided with them is a 2-channel Tx
A 2ch Tx only provides the follwing:
1> throttle: It is either full power or no power.... it doesn't have much control over the speed.
2>Left or right: Decided by variator on the plane. The turn is decided by the amount of power that's passed to each of the 2 propellor motors.

The next important thing is the payload... Electric flyers carry themselves up with great difficulty, forget carrying anything else. Since their C.G (Center of Gravity) is criticially calculated, if you decide to stick in something extra, things get really tricky.

One more thing that should be taken into consideration is the material used. As mentioned earlier, they can't take a lot of weight, obviously the material used for making them is light; foam thermocole. Very fragile & very light. Things appear much stable on ground, but change as the flyer attains height. It becomes hard to control. Especially because, even after being categorized a toy, the rotating propellor blades can cause heavy damage, one is supposed to fly it in a big ground. Usually, in such places the wind condition has to be taken into considerations. They play an important hand in deciding whether or not you'll ever get your flyer back in 1 piece.

I'm sorry if it sounds negative, nobody said this hobby/project was cheap.

If anybody wants, they can buy those things.

One more thing, vidur... Electric flyers are the best trainers, but you need expert on-site guidance, without which you'd be lost like a 6 year old in a strip club (don't fantasize about being that kid!!!)

Regards,
JeDi

vidur
06-02-2005, 06:42 PM
Dear Jedi .........What r u saying yaar

A small ckt would not even add 50gm to the weight......The plane weighs a mere 9 oz ( 250g)
& the picture i saw was definately not thermocole....it was plastic.& was not engine powered

Check this one out

http://cgi.ebay.in/ws/eBayISAPI.dll?ViewItem&category=2563&item=5978303788&rd=1

I'm not asking to make a flyer that is equvalent to a X-43 plane!

Only to get ppl started!


I still dont see the problem

jediknight
06-02-2005, 11:15 PM
Hello vidur,

Like I said in my previous post, if you want to buy, go ahead.

I said it once & I say it again... the material used is foam thermocole also called as "Styrofoam" (the spelling might vary).

Please refer to the URL & my post, you'll see a lot of things that I said were similar.

One more thing, when we're talking about Boeings or Airbuses, 50gms make no difference, but when we're talking about aeromodels, even 10gms can make or break your flight. Take my word for it, mate... I've seen it happen. Don't take my word for it, get a thermocole sheet, cut it in shape of the wing, attach any spare telescopic antenna as shown in the figure, get the C.G (Center of Gravity), put 50gms either in front of C.G or behind it, you'll see the difference.

Before I leave, I'd like to get your attention towards a couple more things.
1> The 2ch RC: The control lever on the left controls the throttle to the propellors (Full power or no power, you cannot adjust the amount of power sent to the motors).
2> Absence of Alerons, Elevators & Rudder: Like I said, it has got only 2 channels of control; throttle & left/right turn through variator. It doesn't provide effective turning or manoverability of the model.

Think a gazillion times before buying such things, unless you really want to learn under expert supervision or else, it's complete waste of your hard earned money.

I'm sorry if I sounded rude, but I'd rather be rude & save somebody's money than be polite & let somebody waste their moolah.

Best regards,
JeDi

jediknight
06-07-2005, 05:24 PM
Oh, there are a couple of changes about my project...

We're no longer using "Tyro" as ur aeromodel, neither we're using "OS 46FP" engine.

We're using a yellow "Piper" & fitting it with "OS 52" engine.

Professional pics are still awaited, things will be decided only after the trial run that we're hopefully taking tomorrow.

Regards,
JeDi

jediknight
06-07-2005, 06:30 PM
Here's the pic of what I'm talking about..

Our model is yellow in color too, a lot more bigger than this plane, has gas engine mounted instead of DC motor & of course, made totally in Balsa wood, no styrofoam used.

http://www.sierra.ro/import/aeromodele/avioane_cu_motor_electric/seria_400/img/Piper%20400.jpg

Regards,
JeDi

vivek_bye
02-11-2006, 01:51 PM
hi people,
even i have been wanting to build an RC plane from many years. but this year i have decided to get my first plane in air. i have started to learn about aerodynamic concepts, possible materials, radio components for control and also motors and may be servos for controlling the flaps ailerons rudder and maybe horizontal stabilizers. the problem is i know nothing about electronics :( so u guys have to help me with that. at first try i am not trying to put a video transmitter and gps tracking or even gyroscopes. i just want to get airbourne atlest.
can you guys help me with these questions..
where to find basic radio transmitters/recievers with about 50 meters range and about 4 channels . (or is there a way to control many components with few channels??? ) also how much small can they be coz they have to be as light as possible.

docel
04-06-2006, 09:23 AM
hi,
India Hobby Centre, chennai.