AmyS3
Posts: 173
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Re: UAV

Fri Aug 05, 2011 10:33 pm

this topic will cover all information regarding my uav project.
since i can´t make subtopics im having some initial posts for different sections of this project which i´m going to update from time to time.
all other post from you lot will be located after those "sections" to have it nicely sorted.

i will sort it a bit better later on and put in more infos, so please bare with me ;-)

Project description
The maingoal of the project is to create a uav (Unmanned aerial vehicle) which is able to stay in the airspace for an endless time without the need to land exept for emergencies.
therefore this uav will not be a plane in common sense.
instead it is going to be shaped more like a zeppelin and be helium backed to reduce the weight of the uav to save energy which is needed to drive the electronic devices.

Project goals
Aircraft body model
circuit wiring
Flyable (maingoal)
Autopilot
Relieable power source
Emergency Landing
Endless Fly

AmyS3
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Re: UAV

Fri Aug 05, 2011 10:34 pm

Materials

i will add a "bill of materials" with links when the final setup is determined.

Computing
Raspberry Pi - Model A (1x)
DS3234 RTC for timing the mcu´s, communication stuff and power management
Several other MCU´s for power management and other stuff. details later
Power
7.4V 5.2Ah 20C Lithium Polymer batteries - Connected in Paralell (2x maybe more)
0.5V 4.8Ah Mono Solar Cells 5" x 5" - Connected in Series (20x probably more..)
Charger IC MCP73871-2CCI/ML (4x)
Navigation
GPS Sirf3 Navilock NL-303P (1x but it uses to much power need to change)
Tripple Axis Magnetometer HMC5843 (1x)
Tripple Axis Accelerometer ST LIS3LV02DL (2x maybe a different chip later on)
Sharp GP2Y0A02YK0F 15-150cm (4x)
Dual Axis Gyroscope LPY5150AL (2x)
Communication
Wifi (model will be one which works with the raspi)
AM RF Transreciever (for long range transmission. model not selected yet)
Quad-Band Mobile Phone with serial interface for worldwide transmissions
Imaging
RGB Camera Module with added zoom (model is not selected yet)
Movement
Model Craft ES-05 Analog Mini Servos (2x)
Model Craft TS-11 Digital Micro Servos (3x)
Unknown Servos (4x - used for the impellers. model not selected yet)
65mm Impeller (4x - forgot the name of the maker. for the motors as well)
maybe i swap them completly for a lighter version

Body
Helium (where can i get decent helium in the uk?)
Lightweight Foil (for the helium unit. type not determinded yet)
Balsa Wood (as base for the solar module and some framework)
Linen (body shell. but linen is heavy. maybe i use something else)
Aluminium (framework)
Plexi Glass (as cover for the solar module, camera and sharp sensors)
Epoxyd Glue
Silicone
Random parts
Lead

AmyS3
Posts: 173
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Re: UAV

Fri Aug 05, 2011 10:34 pm

Circuits

All circuit schematics and pcb layouts will be aviable in this section and indicated regarding they´re state.

Charging
the charging circuit is a harder nut than i first thought since the main batteries
are 2 cell lipos where both cells should be charged sepperatly to maintain a long
and stable battery life.
it would be more easy if i could use only single cells because it is easy to charge them and still be able to power the system during the charging state.
but i need a higher voltage for the servos and motors.
so i curently trying to figure out how charge the cells sepperate and still be able to use them in series to get the 7.4V.
if i can find low power servos somewhere that problem would be solved since im sure i can get motors with a lower voltage for the impellers as well.
any help is apreciated!

edit: i´ve done some resarch and it seems that it is possible to drive several servo types from a single lipo cell. i will test it with the servos i have in stock and update the results later on. it would be fantastic since i would have 20.8Ah with the lipos to play afterwards.
then i can change the solar cell setup to generate 5V and ~9-10Ah as well.
if all goes well i can finally start developing the circuit.
the current power setup contains a solar module which delivers ~10V and ~4.9Ah.
and two 7.4V 5.2Ah dual cell li-po batteries.
the desired power configuration should be able to charge the batteries in a balanced way and powers the rest of the system from the solar module when the sun shines and use the charged batteries to power the system at night.

AmyS3
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Re: UAV

Fri Aug 05, 2011 10:35 pm

Software

AmyS3
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Re: UAV

Fri Aug 05, 2011 10:35 pm

Crafting

here is a veeeeery rough drawing of the desired shape.
don´t nail me onto that since the size and shape will change during the process.
i still need to wait for all materials so i can weight them and calculate the volume i need for the helium to support the weight..
not to speak about airodynamics...



somehow it looks more like a futuristic submarine

AmyS3
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Re: UAV

Fri Aug 05, 2011 10:37 pm

feel free to add comments now ^^

im thankfull for all help regarding the project or writing errors in the descriptions.
since english is not my native language i have some grammar problems and capitalizing as well.

ShiftPlusOne
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Re: UAV

Sat Aug 06, 2011 12:17 am

Is this a university project or just a hobby (or both)?

AmyS3
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Re: UAV

Sat Aug 06, 2011 12:23 am

well a hobby but maybe i get a contract with the airforce later on XD

jonititan
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Re: UAV

Sat Aug 06, 2011 2:11 pm

It is a bit of an odd shape for a lighter than air craft.
I would expect to see a structural weight penalty if you use that shape.
Cylinders and spheres are generally used as they represent the best balance of gas volume, structural integrity and lowest weight.
Do you have any experience with rc fixed wing models or lighter than air models?
The challenge is to build a suitable vehicle which can lift enough weight to carry all the sensors and processing elements to be able to operate as a UAV.

AmyS3
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Re: UAV

Sat Aug 06, 2011 10:27 pm

this is exactly what i want to achieve.
and you´re right about the shape. i´ve done the sketch in 3 minutes.
the only problem with a normal cylindrical shape is the bigger side surface which can be attacked by wind.
so i want to try to make the shape more "streamlined" to gain a better airodynamic behavior without loosing to much efficiency for the gas volume and weight of course.
given the fact that the uav weights litteraly nothing, it can be attackt by wind very easy.
well thats what i think... please correct me i im wrong.!
this is my first lighter than air model. i had several "normal" rc planes, gliders and 2 helicopters so far.
and i´ve been flying a small plane and a glider myself as well. so im a bit experienced in flying itself.

edit: you can think of the shape as a flat pressed cylinder. so the balance of gas volume and weight would not be affected..
for stability i make a fixed "outer" body where a sepereate helium bag will be inside.
you can create quite hard shells with treated fabric. but im still checking for a lighter version.

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abishur
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Re: UAV

Sun Aug 07, 2011 1:34 am

Sounds fun! What are your long term goals with the project? Do you plan on sending it around the world (or at least around your city)?
Dear forum: Play nice ;-)

AmyS3
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Re: UAV

Sun Aug 07, 2011 1:41 am

around the world.
but first around my town to test if it is safe :-)

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abishur
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Re: UAV

Sun Aug 07, 2011 3:23 am

It would be pretty awesome if you could do it in 80 days! :P Any thoughts about dealing with crossing country boarders? Do you have any contingency plans for storms (especially over oceans?)
Dear forum: Play nice ;-)

ShiftPlusOne
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Re: UAV

Sun Aug 07, 2011 3:38 am

I know it's a headache to get one of these off the ground legally... to do it over several countries would be pretty much impossible.

AmyS3
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Re: UAV

Sun Aug 07, 2011 3:50 am

80 days would be great XD
but i dont think it will be finished so quickly.
the cross country borders are a real hassle. i had some insights in that during a little tour on the lunar x-price. where they discuss that topic for the rocket launch which includes several countrys because the rocket will pass the airspace of them on its jurney to space.
but the main aspect was the damage which a rocket can generate when its comming down on an error.
the only harmfull components of my uav are the lipos.
but i would be not the first one who sends a uav like airplane across countrys.

the main emergency plan for heavy storm would be landing... given the fact that the uav is hollow, it will float on water if it would be over the ocean :-) in continental areas it is a different topic. but normaly you can escape those storms if you gain a high altitude.
well but the maingoal would be to navigate around big storms.

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abishur
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Re: UAV

Sun Aug 07, 2011 2:01 pm

For the board thing, you could try going an ocean route around the world. It would take a lot longer, but oceans are open territory
Dear forum: Play nice ;-)

AmyS3
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Re: UAV

Sun Aug 07, 2011 5:14 pm

that´s true.
maybe there is also a way on a continental route if i skip the military and commercial airspace.
since the uav can be controlled remotly as well, it can be considered as a "normal" rc-plane...
but the restrictions for flying models are sometimes pretty strict.

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Lob0426
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Re: UAV

Wed Aug 10, 2011 10:35 pm

AmyS3: why do you need the 20C recharge rate? This will be an advantage during testing but extra cost over 15C if you are planning a solar recharge. Don't the 20C cells have a faster loss rate? What is your projected discharge rate?
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AmyS3
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Re: UAV

Wed Aug 10, 2011 11:26 pm

the 20c ones are the cheapest 5.2Ah cells i could find at the moment. and i like to have a "little" power kick possiblity as a reserve for emergency ;-)
im going to splitt the battery packs from dual cell into single cells for a higher current of 20.8Ah in total.(yes i bought 2 battery packs ^^)
then im going to power the raspi with 3.3V since i dont need the hdmi or usb ports.

the solar cells will provide around 9.6Ah at 5V.

each lipo cell will be charged at a max. of 1A, which makes ~4.5-4.8A in total, including the power loss of the charger chips (i calculated quite generous).
the raspi will drain ~0.3A on 3.3V.
makes ~5A in total.
leaves a bit more than 4Ah for the rest of the system and even more when the lipos are fully charged. well in fact, even during the charging cycle will the system have a higher priority than the lipo´s which makes it possible to use the full solar power plus the power which could be in the lipos. its a very crazy circuit..

as for you´re question about the discharge rate, the charger circuit will have a discharge rate of ~1mA.
the power converter ~3mA.
a additional power management ic with it´s child ic´s and components will drain another ~45mA.
dont know about the lipos yet since i have to wait until they arrive and i can test them (estimated delivery is end of next week).
makes ~50mA when the raspi and the rest of the system(motors,sensors...) is off.

im still calculating and investigating the power consumption for all other system parts. like the sensors and stuff..
im currently at ~300mA which covers all sensors exept gps.
the servos and motors are still in an investigation state. but they will not be used all the time anyway.

i hope this gives enough information for now.. when i have more infos, i will put them in the project detail posts.
but i still have quite some calculations to do...

Cool.Majkl
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Re: UAV

Thu Aug 18, 2011 7:25 pm

If I think that it is what it is, then it is awesome. I have a few questions. If I get the concept right - The plane will comunicate with earth, right? I guess it will send some data back to earth, right ? Do you want this plane to stay in outer space or in atmosphere? How much you expect to cost all these parts?

Sorry for so many questions, but I'm starting to love this project, because I always wanted to do something like that.

Still you/we all must think of some project name (such as Project Enterprise :D).

carf
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Re: UAV

Sun Aug 21, 2011 8:35 am

Have you checked out
http://diydrones.com/profiles/.....-main-page ?

I was thinking of using the Pi as a wireless webcam attachment for an RC Plane UAV

sh4d0w0lf
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Re: UAV

Sun Aug 21, 2011 3:03 pm

I like your idea, I was thinking of making a security drone to watch over my motorcycle whilst at work a year or so back. The main problems would have been getting it to keep up with my bike and keeping it up in the air (for a normal winged rc aeroplane this would have been a problem).

Back on subject, the idea is good however it would be a huge challenge to undertake..
How would you set about communicating with the UAV whilst it is over seas? satellite phone maybe? or satellite internet device if something small enough exists? Have you got a recovery plan incase something goes wrong? Last but not least, If you fly your UAV over continents you'd eventually come across mountains.. How would you deal with this?

I wish you the best of luck in your project and am watching with interest

toxibunny
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Re: UAV

Sun Aug 21, 2011 3:51 pm

"security drone to watch over my motorcycle whilst at work"

YOU ARE AWESOME
note: I may or may not know what I'm talking about...

AmyS3
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Re: UAV

Sun Aug 21, 2011 4:20 pm

Quote from Cool.Majkl on August 18, 2011, 20:25
If I think that it is what it is, then it is awesome. I have a few questions. If I get the concept right - The plane will comunicate with earth, right? I guess it will send some data back to earth, right ? Do you want this plane to stay in outer space or in atmosphere? How much you expect to cost all these parts?

Sorry for so many questions, but I'm starting to love this project, because I always wanted to do something like that.

Still you/we all must think of some project name (such as Project Enterprise :D).

yes it will communicate with earth..
it will stay in the earths athmosphere since you cant send a helium based plane into space..
the total cost for this project is targeted to stay below 1000 pound.

the comunication from/to the uav is based on 3 different ways.
wifi for short distances like at the homebase.
mobile phone for medium to long range like inner country or international(if possible).
radio for long range and over ocean communication.
the uav will decide on ist own which communication type it is going to use based on the location where it currently is.

to avoid mountains or other obstructions it can use the gps to stay high above the mountains or if it´s in surveillance mode on lower height it has some distance sensors which sense a obstruction below/front/back/sides/top.

AmyS3
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Re: UAV

Sun Aug 21, 2011 4:20 pm

double post...

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