Pre project questions thread (quad copter)

[large_ghostman]

Finally getting around to doing my quad copter! I am going down a slightly different route to most, but more on that later. I have watched loads of vids and tutorials but I still have a few questions.
I am probably going to make the frame from a couple of broken fishing rods made from carbon fiber, I have it to hand it strong and light.

Are the little vibration motors powerful enough for use with a small quad copter?

I would like to use mobile phone batteries in parallel to power the motors, are these a good choice or are there better ways weight for weight?

If I get a load of solar cells that you solder yourself, is it worth covering the thing in them to help charge the batteries? or are they a waste of time and energy considering the extra weight.

What motors would you use? and why?


Sorry for the question's but about the only thing I am fixed on using at the moment is the frame, and the transceiver which will be incorporated into a micro and run at around 868 MHz, I have some boards for this chip and its great for building a custom remote control unit!
Thanks for any help

 

[skimask87]

Haven't built a quad myself, but have kept up with the times as far as what's what in the arena...

I am probably going to make the frame from a couple of broken fishing rods made from carbon fiber, I have it to hand it strong and light.

Good enough...as long as the interconnecting pieces/parts are strong as well. Then again, maybe those want to be a bit weaker for a cheaper breaking point. Don't know. Depends on how you design it.

Are the little vibration motors powerful enough for use with a small quad copter?

Not even...unless you're building a REALLY small quad.

I would like to use mobile phone batteries in parallel to power the motors, are these a good choice or are there better ways weight for weight?

I wouldn't. Mobile phone batt's are engineered more for a lower current draw and longer life rather than dumping a lot of power "right now".

If I get a load of solar cells that you solder yourself, is it worth covering the thing in them to help charge the batteries? or are they a waste of time and energy considering the extra weight.

Again, not even. Solar panels weigh a lot more than they're worth on almost anything flying, or driving for that matter. Those might be best built into a panel that keeps your quad charging battery topped off.

What motors would you use? and why?

Depends fully on the design, weight, performance expected, batteries powering it, moon phase, oh, and don't forget color of the blades

 

[large_ghostman]

Ok ditch the phone motors and batteries! keep 2 small solar panels (they are plenty to power the micro I have in mind), So I am looking for a small powerful motor that dosnt weigh much! Obviously if I find that then its likely to be able to do my homework as well!
So next in plentiful supply in the might be handy one day box, is hard drive motors? they spin up pretty fast and are fairly small? thoughts on these?
Size wise for the copter I am not sure, but enough to lift a power source to keep it flying for 30-40 mins (yeah tough one).
Crash protect will of course be built in by some kind of mad system involving a way over the top micro etc (the hall mark of my projects), one of those sonar distance things in case things get sticky, and some small diameter carbon fiber rods on springs to be deployed in an emergency so my machine survives a crash (it wont crash).
So many designs out there but not many I like. The propeller thing is a night mare, might be easier to get some drawings and do them on the CNC.

 

[skimask87]

The solar panels will add a lot more weight than they'll be worth in terms of power making and any microcontroller system you put in there will draw such a small percentage of the total power pulled by the motors it wouldn't make much sense to try to lift the extra weight of the solar panels.
Solar panels, on a good day, if they're angled just right (which they won't be most of the time), will get you about 10 watts per square foot, give or take, at a weight cost of a couple pounds for that square foot. Much better off "spending" that extra pound or two in a couple more LiPo packs.

 

[large_ghostman]

Your just spoiling my fun!!!!! but point taken, so what about HDD motors? any good power to weight wise? I know its hard not knowing much about what I am going to build, but then again I dont really know yet either!
I might take a couple of motors out and see how much power they draw and how much oomph they have, they cant be that bad. I did have some old FDD motors, really really old ones, they had loads of go in them for the size, same as some of the old CD drive motors I had kicking about.
Or do I go the petrol model airplane motor route now there is some serious power!! but probably a bit tricky to get balanced power wise and not very fast to react to change in throttle (compared to electric). Also expensive! OR electric model aircraft motors, but to me thats kind of defeated my make it from scrap sort of thing.
So how come you havnt built one yet?

 

[large_ghostman]

This is what I have in mind for the wireless transceivers! https://www.silabs.com/Support Documents/TechnicalDocs/Si106x-8x.pdf
The main processor I am going to use a over the top 32 bit one lol I have the dev kit for the chip above, I have had
3 1/2KM range on it so far with two AA batteries in each board!
Loads of channels on it and a 8051 processor in it as well! so That's my comms sorted

 

[skimask87]

HDD motors - not so much. Not made for that kind of work, bearings are all wrong (no thrust bearing)
Petrol engine (whether it's gas, diesel, glow fuel, etc) - meh...I've played the R/C game long enough to know that at best petrol fueled engines are semi-reliable at best. Not to mention they've got a lot of spinning mass...makes it tricky to get them to change speed quickly.

As far as control and wireless, I'd keep the two separated. At least that way, you can upgrade the one without messing with the other. Not to mention with your solution, you have to come up with the antennas, etc. Just buy something ready made for the RF side of things. Helluva lot easier that way and probably cheaper in the long run.

How come I haven't built one yet? hell, I don't know. Would be one of the cooler projects I've ever done if I did build one. Windy as hell where I live in N.D. No real need for one. Got 16,493 other projects to do first
For now, I'm kinda sticking with messing around with those cheaper 3.5channel counter-rotating blade helicopter, just to mess with the kids and the cat. I plan on buying a larger one to mount a camera on and hack into the IR remote, change it over to RF, etc. Eventually I'll get there...

 

[JimB]

A few thoughts:

HDD motors, while they can rotate very quickly, all that they are doing is spinning a highly polished disc in still air, there is very little work being done. So all in all a bad idea.

Build it from junk, sounds good to me, but it needs to be the correct type of junk.
Say that you want to build an aeroplane, what to use for the engine, a 150BHP 3litre engine with a cast iron block taken from an old Austin Healey 3000, or a 150BHP 1.8litre engine with an aluminium block taken from a 2 year old Mazda MX5 (that has had a nasty accident!).
No contest go with the smaller, lighter engine.

Use a model aircraft motor, electric will be much easier to control.

Crash protection, things on springs? !!!
More weight for your unknown motors to lift.
Think like John Cooper (racing car designer) and "build in lightness", the easy way to go fast, or up in the air.

To find out what is practical, do some tests.
Get some motors and propellors and see how much lift you can generate. Use weighing scales to measure the lift.
Then you will know what motors work best and the maximum weight of your quadcopter, then you can build in lightness by leaving out all the un-neccessary stuff.

JimB

 

[Pommie]

I recommend having a good read over at https://diydrones.com/ before starting.

If you are aiming for autonomous control then have a good read of anything that mentions Direction Cosine Matrix.

Have fun.

Mike.

 

[Nigel Goodwin]

Your just spoiling my fun!!!!! but point taken, so what about HDD motors? any good power to weight wise? I know its hard not knowing much about what I am going to build, but then again I dont really know yet either!

Electric powered models are a relatively 'recent' innovation, basically because suitable motors became available - you really need the proper motors to make it viable, and certainly not motors intended for entirely different purposes (such as HDD or vibrator motors). They might be expensive, but there's good reason for that.

 

[large_ghostman]

I found DIY drones last night, great site! Yes after much reading all my assumptions on motors were wrong. I might have to bite the bullet on that one and buy motors . The radio side is separate, the chip does have a 8051 core built in but the intention is just to use it for Comms, everything else will use a CORTEX M4 I have been playing with.
The antenna isnt an issue, with the wireless kit I have there is a antenna dev kit I have as well, I will use one of the small pcb antenna's from it (post link later).
I have set up a small test rig see how much oomph they have.
I would love to be able to get it to do autonomous flight, not sure how hard that would be. The micro I have in mind is certainly powerful enough. I will read up on the stuff mike suggest, one reason I chose the main processor is because it has a built in FPU and good speed but low power consumption, it will be one of the wonder Gecko range not sure which yet.
I got a shock at the cost of props!! I have a sample of a new magnetometer chip I will try out today. The accelerometer
I have is a slightly older chip I might send off for a sample of some the newer ones.
Thanks for the help!
BTW being the holidays (although I am still not allowed back anyway) I managed to get alot of the frame done yesterday, it comes in at around 30 grams, I could get this down by using the thinner sections of rod.

 

[audioguru]

Go to a hobby store and see all the small radio controlled quad copters. They all use Li-Po lightweight batteries. The hobby store will sell you the motors, propellers and batteries.
I saw one that was so small I could cover it with one hand. Most use motors similar to vibration motors and have brushes that wear out soon. Almost all quad copters have gyroscopes (MEMS accelerometer ICs) to make them very stable. Their flights last about 5 minutes to 10 minutes then the battery needs to be replaced and re-charged. Many can carry a keychain camera.

 

[skimask87]

Ya, I don't know about the keychain camera thing...
I've got a couple of those 7 inch models, as well as a few of those really small keychain cams.
Tried mounting the can on both heli's. All it would do is scoot across the floor. Took the batt out of the one heli, paralled it with the batt of the other heli. Got it to go just barely out of ground effect for maybe 5 minutes on a charge.
Camera is an 808 micro typoe, heli's are s109g types.
However, one of those 3ft rotor types with the battery mod would do a pretty good job of lifting way more than a few gramns.

 

[4pyros]

Hi; Sounds like another fun project.
Its all about the weight. Every thing needs to be as light as possible.
You may have to bite the bullet on the motors, and get RC plane motors and props. They are made as light as possible and as efficient as possible witch means they will be more expensive. Anything you can find laying around will be heavy and power hungry because its cheaper.
As for the frame you will want to make it as easy as possible to replace parts and rebuild after a crash.
Springs and stuff would just add to much weight. The pro ones are made to brake but can be fixed fast.
Make plenty of spare parts and don't use anything that is hard to reproduce.
It will crash! and break stuff you will need lots a spare parts.
Keep every thing as light as possible. Short thin wires, minimal connectors less solder and so on.
Keep the bolts as short as possible and don't use washers. Tap treads in holes instead of using nuts.
Think long and hard about weight reduction.
Have fun!

 

[large_ghostman]

Go to a hobby store and see all the small radio controlled quad copters. They all use Li-Po lightweight batteries. The hobby store will sell you the motors, propellers and batteries.
I saw one that was so small I could cover it with one hand. Most use motors similar to vibration motors and have brushes that wear out soon. Almost all quad copters have gyroscopes (MEMS accelerometer ICs) to make them very stable. Their flights last about 5 minutes to 10 minutes then the battery needs to be replaced and re-charged. Many can carry a keychain camera.

I am a fairly long way from any shops that sell that sort of thing, I have the gyroscope and accelerometer and a magnetometer on order (samples), makes you wonder how Amazon intend to use them for delivery of books lol, maybe I should wait for that to happen, then all I have to do is order a book and grab it .


4pyros my quad will not crash!! I wont allow it, . I have one of those helicopters with the weights on rods that help keep it straight etc, I only used it twice before it gave up! The radio control unit was utter rubbish, the batteries leaked after 3 weeks. It was cheap and Chinese, the only good parts were the large size and well built large frame, the motor was pretty good as well. It had nicads in it they weighed a fair bit so I know it can lift a fair bit. Maybe I will just start with redoing that, rip the inside out replace the servo's etc and build my own controller.
Might be a good thing to get into while I wait to save up for some decent motors!

 

[audioguru]

I saw this tiny quadcopter flying in my local hobby store. It costs $44.95 Canadian with the toy transmitter:

 

[large_ghostman]

Thats pretty cool

 

[large_ghostman]

I recommend having a good read over at https://diydrones.com/ before starting.

If you are aiming for autonomous control then have a good read of anything that mentions Direction Cosine Matrix.

Have fun.

Mike.

I have had a long long read over there, excellent information but proves I have yet again over simplified in my mind what was needed. I assumed it would be pretty straight forward, so what I am going to do is get my old helicopter up and running, use that to make my own controller (I have a good reason for this), this will stop me getting bored and fed up while I prepare for the quad. I have put my bike and other stuff on ebay this weekend along with some other bits. I will use the money to get some decent motors, yes I could use cheaper ones but little point.
One thing that has come out from this is the petrol aircraft engines, I have a small one thats very old. At some point I would love to try and connect this to say a battery powered drill motor and use it as a generator!
Yes unreliable, yes heavy, yes in many ways pointless. BUT it appeals greatly to me, I really like the idea of a petrol motor supplying the power to the electric motors, I am aware that as many have pointed out this will lead to tears, but it is a good learning path to follow, I am not expecting success or gaining of advantage from it, but I will get great building practice and good experience from it.
I am not an engineer (yet) that has a problem to solve, I am a kid that wants to learn and have fun, building chocolate teapots may seem like a waste of time but I always get something from it, please dont think I dont listen because I do, please dont think I listen then ignore the advice because I dont!
What I do is way it all up, with the advice given I know I can build a good quad copter and I will, but along that path I am going to try out some the things I now know wont work well.
I know that seems daft but I decided the building process etc and what I had to gain from it, outweighed the end failure.

Now this Direction Cosine Matrix.
I have been reading and my maths is not upto this!!! So before I get over ambitious I am going to try and get the maths for it upto scratch, I dont want/need full autonomy but will still need to know and understand Direction Cosine Matrix.
So I am splitting my project, get the copter up and running again and replace all the crap electronics on it, build my own controller for it. By the time thats all done I should have the right motors and some good knowledge and build skills.
One thing I cant decide is the main processor.
Mike out of these two processors which would you choose?

EFM32WG990F256 : it has FPU and is CORTEX M4 based
datasheet attached

or
EFM32GG990F1024
datasheet attached, its Cortex M3 based but has alot of memory and a really advanced maths lib

Which is going to be better for the maths side of things? I chose these because 1 I have access to the dev kits and 2 I can get the chips free and sponsorship for the boards to be built

 

[large_ghostman]

Well spent the day working on the helicopter, its pretty big and I should post some pics. It was cheap and it shows in many ways, but it has a good aluminum frame and a good motor, the batteries were never very good (nicads) even new they didnt hold a charge for long, the copter would short something when you ttouched it sometimes and it would spin the large blades catching your fingers! I had a really deep gash from one incident, but it only flew 3-4 times before I gave up on it.
Looking at it today the rear pole part has a bend in it (from moving house I think) I need to sort that somehow.
Its about 3 feet long (for you older people), after reading DIY drones I am tempted to spend some time on this instead of a quad copter. The nicad pack is pretty heavy and it lifted off the ground no problem, so I know its got some grunt in it, the control unit was total rubbish as are the servo's, but I can replace all that easy enough.
The plastic nose cone is thin cheap and cracked, eventually I will make my own for it. But I think its a good candidate for new electronics! The Transceiver chip I linked to above with the 8051 onboard, can do the basic reading of RPM and battery charge etc and send back to the controller display, the rest of the electronics and control systems I will use one of the two chips listed above.
I have sent off for a couple of samples for accelerometer,gyroscope and magnetometer. If I swap the batteries for Lipo and take out the rubbish inside, then I have plenty room and capacity to add in a few things, the servo for speed control is large and not very good, removing that and doing pwm for speed control will save enough weight alone for a half decent GPS unit.
Finding a half decent cheap GPS not so easy!
I also want to add in the ultrasonic distance things, I had one of these boards and they dont weigh much and are easy to use.
I might be able to get it to help prevent a crash!
I have crashed the copter before and the bar with the weights on tends to get bent, but apart from that the frame seems pretty robust.
Anyway thats the plan for now

 

[large_ghostman]

mis posted

LG