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Offline cyberfishTopic starter

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Something that flies
« on: July 10, 2010, 09:01:16 PM »
For my next project, I am planning to build something that flies.

I have absolutely no experience in that before, so some advices would be much appreciated.

1) What is the easiest controlled flying device to build/fly (including control algorithms for stability, etc). A quadrocopter or airship? Speed is not a factor, but I want to fly outdoors at low altitudes (50-100m?), so wind will be a factor.

2) Any recommendations for radio? I'm hoping for 1km LOS range.

3) How much would it cost approximately? What level of skill is required? I am going into third year electrical engineering, and I would say I know quite a bit more than most people at this stage. I have also been programming for ~5 years now, and am doing some internship now in a developer position, so I'm guessing programming won't be the hard part.

I have very little mechanical knowledge, though. Ends at first year physics. This worries me :).

I would like to keep this project below ~$500.

Thanks!

Offline Alfa_Zulu

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Re: Something that flies
« Reply #1 on: July 10, 2010, 09:34:44 PM »
well, I was planning to make an autonomous quadrucopter using a gyro to keep itself level and avoiding objects.
later upgrade was to make it controllable via an iphone over bluetooth/wifi, you'd basically just tell it to move forward/back or whatever and it would change pitch/roll a little amount to make itself move. If you knew what you were doing with programming I wouldn't image it'd be too difficult to implement.

but as I said it was just an idea I had.

Offline cyberfishTopic starter

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Re: Something that flies
« Reply #2 on: July 11, 2010, 01:47:21 AM »
Yeah that's my idea, too. Except I'll probably go for higher power radio and fly it around my neighbourhood or something.

But I'm sure more problems will come up :).

Offline Joker94

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Re: Something that flies
« Reply #3 on: July 11, 2010, 04:39:12 AM »
i am currently working  a UAV so do have some experience in the electrical side of flying robots.

if it was me i would choose a plane for your first flying robot as in my opinion it is a more stable platform and offers a better platform for your first venture into flying robots.

you can make it as complex or as simple as you want to. you could have a basic path programmed and have that initiated by a switch on a RC transmitter or you could have a system that incorporates GPS, gyros altimeters, telementary, human control etc. the options for a flying robot are endless.

there are many different means of transmitting data. there are systems out there that can transmit tens of miles, but for something that flies around the neighbor hood you will be able to use a RC transmitter it is just up to you on the range that your happy with. the spektrum radios can be plugged into the computer and then data sent through that radio.

before you go on there are a number of decisions to make. what kind of flying robot do want? how much work do you want to do ( are you happy to design your own processing, do you want to)? what would you find more enjoyable ( i find planes more enjoyable than quadrocopter as i love planes, have always and i also fly rc planes) what do you like more, what do you have the greater passion for.

goodluck, and happy to help with any questions

Joker94

Offline dunk

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Re: Something that flies
« Reply #4 on: July 11, 2010, 05:22:43 AM »
1) What is the easiest controlled flying device to build/fly (including control algorithms for stability, etc). A quadrocopter or airship? Speed is not a factor, but I want to fly outdoors at low altitudes (50-100m?), so wind will be a factor.

a quadrocopter is far more complicated to get working than everyone thinks.
the point everyone misses is that while developing every mistake involves a crash.
many crashes involve broken parts.
broken parts involve more money and time.

95% of people who arrive on the various forums (diydrones.com , rcgroups.com , etc) talking about building a quadrocopter never get much further than buying parts.
i don't mean to put you off, just think about it before committing.

an airship would be *far* less trouble in this regard but not nearly as cool.

fixed wing aircraft are far easier to learn to fly than anything with rotors.
they tend to require a larger flying field though.

2) Any recommendations for radio? I'm hoping for 1km LOS range.

most people use of the shelf RC equipment for this then decode the servo PWM signals on the aircraft.
in my opinion this is an ugly solution but most people doing this have a lot of experience with RC aircraft so it is what they know.

have you seen my project?
http://sites.google.com/site/mrdunk/

other interesting options are this thread on RCgroups.com: http://www.rcgroups.com/forums/showthread.php?t=801036

using XBee modules also looks promising at first glance but the Zigbee protocol causes quite a bit of latency which you may decide is too much for your application.

3) How much would it cost approximately? What level of skill is required? I am going into third year electrical engineering, and I would say I know quite a bit more than most people at this stage. I have also been programming for ~5 years now, and am doing some internship now in a developer position, so I'm guessing programming won't be the hard part.

that depends a lot on your design.
i could rebuild my entire project for around 250Euro.
if you take fly away planes and crashes into account the whole project has probably cost twice that much.

the time investment is the big one though.
i have easily spent > 500 hours on developing my system.

if you plan to design and build every aspect of a flying robotics platform expect a similar time investment.

obviously there are online plans to speed this up.
if someone was to use my design of the one on RCgroups.com they could build a working radio system in a month or two.
another month or two and you might manage to build an aircraft from online plans.

you will crash the first one you build though. and probably the 2nd one too.


dunk.

Offline random robots

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Re: Something that flies
« Reply #5 on: July 11, 2010, 06:30:15 AM »
I'd bet you could you could keep  the project under 50 dollers if you were as much of a cheapskate as me ;D. okay so down to business.
1. dont build anything near a helicopter! an airplane is cool enough, and its simple.
2. im building an indoor autonomous one, so cant help ya their. sorry
3.if you search enough, the total could be under 100 bucks. It takes a lot of searching to find what you want. I think you should have built a couple of robots before you start this.

i would be glad to help with motors, props, etc.

hope this helps,
Patrick
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Offline cyberfishTopic starter

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Re: Something that flies
« Reply #6 on: July 11, 2010, 03:41:17 PM »
i am currently working  a UAV so do have some experience in the electrical side of flying robots.

if it was me i would choose a plane for your first flying robot as in my opinion it is a more stable platform and offers a better platform for your first venture into flying robots.

you can make it as complex or as simple as you want to. you could have a basic path programmed and have that initiated by a switch on a RC transmitter or you could have a system that incorporates GPS, gyros altimeters, telementary, human control etc. the options for a flying robot are endless.

there are many different means of transmitting data. there are systems out there that can transmit tens of miles, but for something that flies around the neighbor hood you will be able to use a RC transmitter it is just up to you on the range that your happy with. the spektrum radios can be plugged into the computer and then data sent through that radio.

before you go on there are a number of decisions to make. what kind of flying robot do want? how much work do you want to do ( are you happy to design your own processing, do you want to)? what would you find more enjoyable ( i find planes more enjoyable than quadrocopter as i love planes, have always and i also fly rc planes) what do you like more, what do you have the greater passion for.

goodluck, and happy to help with any questions

Joker94

Thanks for the suggestions!

That is very surprising, as I thought planes would be more difficult to build (mechanically), and that's one reason why I planned to start with a quadrocopter.

I do intend for it to be autonomous (probably just waypoints), with GPS, and possibility for human control. I thought it would be much easier to make a chopper autonomous, as it can hover, and stop to make turns. Also things like what to do if it's in remote control mode and the radio link is lost. A chopper can be programmed to just hover in place (assuming the best way to stay alive is usually to stay still...).

For waypoints, I'm thinking something like, ascend to some altitude, turn to face the next waypoint, go straight (adjusting a few times along the way), stop, turn to face the next waypoint, etc.

A plane would need to work out a curved path (I'm assuming).

Slower speed/hover also allows for easier photography?

As for radio, I just checked regulations in Canada, and apparently for an aircraft to qualify as model instead of UAV (which requires certifications, etc), it must be flown with line of sight from the operator. So I guess range doesn't really matter, as even 1km would be further than line of sight. Guess I can just use a XBee Pro, and even have enough bandwidth for a video stream.

I don't really have any preference between plane and chopper, but I think chopper would be easier for my purpose (automation and photography), even if the control system would be a little more difficult. The hardware should be easier, too. Just 4 motors and 4 props.

Quote
a quadrocopter is far more complicated to get working than everyone thinks.
the point everyone misses is that while developing every mistake involves a crash.
many crashes involve broken parts.
broken parts involve more money and time.
Oh yeah, will take that into consideration.

Shouldn't be too bad as long as the expensive parts don't break? Broken frame should be pretty cheap/easy to fix.

I will probably use an xbee to save time, and for a quadrocopter the frame is very simple (basically just a cross, with place to mount electronics), with little/no aerodynamic considerations.

Quote
i would be glad to help with motors, props, etc.
Oh yeah, I'm sure I'll need help in that department soon enough.

Thanks

Offline Razor Concepts

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Re: Something that flies
« Reply #7 on: July 11, 2010, 03:44:04 PM »
I think so far the longest range radio system goes for 14 miles and runs about a thousand dollars, check on the RC groups forum for that. But getting video data that far is another story  :P

Offline cyberfishTopic starter

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Re: Something that flies
« Reply #8 on: July 11, 2010, 03:57:32 PM »
Quote
I think so far the longest range radio system goes for 14 miles and runs about a thousand dollars, check on the RC groups forum for that. But getting video data that far is another story
Yeah I think I'll just stick with XBee Pro.

250kbps (~25KB/s) should be good enough for low resolution low FPS video.

Offline dunk

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Re: Something that flies
« Reply #9 on: July 11, 2010, 04:26:38 PM »
That is very surprising, as I thought planes would be more difficult to build (mechanically), and that's one reason why I planned to start with a quadrocopter.

a fixed wing aircraft can be built so it is aerodynamically stable.
any sort of rotary wing aircraft (eg. a quadrocopter) will always be aerodynamically unstable.
so with a rotary wing aircraft you will need to stabalise the airframe electronically.
this is a very complex area. i sugest you do some reaserch on IMUs and kalman filters.

Shouldn't be too bad as long as the expensive parts don't break? Broken frame should be pretty cheap/easy to fix.

the broken bits will be your propellers 90% of the time. (they are the high speed parts that will break/deform if they touch anything while moving.)
bent motor shafts will be the boggest potentially expensive regular occurrence.

Guess I can just use a XBee Pro, and even have enough bandwidth for a video stream.

XBees are completely unsuitable for transmitting video.
work out your desired picture resolution, multiply by the colour resolution and the number of frames per second.
compare this to the the XBee data rate.
it still looks posible on paper if you don't mind very low resolution and low frame rate but remember XBees are half duplex so if you cram the airwaves with returning video data the latency of data to your aircraft will be very bad.

also, how do you intend to digitise the video data without a powerful onboard processor?

speaking of latency,
XBees are not a good choice if you plan to send control data to the aircraft. although the data throughput looks good the latency is too bad to reliably control unstable airframes.
if you wanted direct radio control of a quadrocopter for example the XBee would be a bad choice.
if on the other hand the quadrocopter could controll it's own orientation and you just feed it direction information, or if you only wanted to control a aerodynamically stable airframe like a glider the XBee would be fine.


anyway,
you have a lot of research to do before you start.
have a look at http://diydrones.com/ .
read *everything* there. most of the problems you will face have already been solved.


dunk.

Offline Joker94

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Re: Something that flies
« Reply #10 on: July 11, 2010, 07:08:53 PM »
read up on all you can, as Dunc said most of the problems you will face have been delt with before.

the biggest factor in a "flying robot" will be time so be prepared to spend the time on the project.

i am also happy to help with any of the RC problems you have

Cheers

Joker94

Offline cyberfishTopic starter

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Re: Something that flies
« Reply #11 on: July 11, 2010, 07:22:05 PM »
Quote
a fixed wing aircraft can be built so it is aerodynamically stable.
any sort of rotary wing aircraft (eg. a quadrocopter) will always be aerodynamically unstable.
so with a rotary wing aircraft you will need to stabalise the airframe electronically.
this is a very complex area. i sugest you do some reaserch on IMUs and kalman filters.


Yeah I am aware of that. I want to keep as much as possible to the electrical domain, though, since that's my field.

Quote
the broken bits will be your propellers 90% of the time. (they are the high speed parts that will break/deform if they touch anything while moving.)
bent motor shafts will be the boggest potentially expensive regular occurrence.

Ah I see. Good to know. That makes a lot of sense.

Quote
XBees are completely unsuitable for transmitting video.
work out your desired picture resolution, multiply by the colour resolution and the number of frames per second.
compare this to the the XBee data rate.
it still looks posible on paper if you don't mind very low resolution and low frame rate but remember XBees are half duplex so if you cram the airwaves with returning video data the latency of data to your aircraft will be very bad.

also, how do you intend to digitise the video data without a powerful onboard processor?

I am hoping to do JPEG compression on the images, or maybe simpler homebrew algorithm. Some cameras have built-in JPEG encoder, otherwise I'll probably use an FPGA to accelerate it (if even 32-bit microcontroller is not fast enough). I am hoping an ARM microcontroller will be good enough at low quality, though.

Quote
speaking of latency,
XBees are not a good choice if you plan to send control data to the aircraft. although the data throughput looks good the latency is too bad to reliably control unstable airframes.
if you wanted direct radio control of a quadrocopter for example the XBee would be a bad choice.
if on the other hand the quadrocopter could controll it's own orientation and you just feed it direction information, or if you only wanted to control a aerodynamically stable airframe like a glider the XBee would be fine.

It will do its own orientation. I intend to have it able to hover even without a radio link.

Quote
anyway,
you have a lot of research to do before you start.
have a look at http://diydrones.com/ .
read *everything* there. most of the problems you will face have already been solved.

For sure. I've already done quite a bit of reading these few days, but still have lots to learn.

Quote
the biggest factor in a "flying robot" will be time so be prepared to spend the time on the project.

i am also happy to help with any of the RC problems you have

Thanks :). I'll probably need help hopefully soon (after I finish my current project).

 


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