My First Quadrocopter Design

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doublemind
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Joined: Sun Nov 06, 2011 10:49 pm

My First Quadrocopter Design

Post by doublemind »

Hello everybody!

I'm completly new to the world of Multicopters. I got a lot of experience in RC modeling and a little experience in Arduino. I'm absolutly fascinated by those great Multi(Wii)Copters.
Cause I'm a design engineer and own my own cnc mill, I started my first design of a Quardocopter based on the MultiWii enviroment.

light05.jpg


The frame is made of 3mm plywood.


Diagonal distance of the motors is 775mm. The Props have a diameter of 9" ==> 230mm.
I'm not interested in any aerobatics. The only thing i would like to do is, some chilled flying and some nice aerial photos.

For the sensors I used the Wii Motion+ and a nunchuck. Placed both on a "Lochraster" Pcb together with an Arduino Pro Mini.
Yesterday I ordered the battery. 2200mAh 2S 30C. The motors are Turnigy 2830 1000KV. First measurements showed a maximum current of 8-9A per motor.

Kind regards
Carsten

tovrin
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Re: My First Quadrocopter Design

Post by tovrin »

nice looking design!

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Th0rsten
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Re: My First Quadrocopter Design

Post by Th0rsten »

Shouldn't it be 3S?
I tried to fly a 2S - way to slow.

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

Cause I'm not interested in winnig a air race, I hope 2S will be okay.
As far as the thrust will be enough. ;)
Some images of current status. Awaiting the middle part before the end of the week.


20111105_12_43_5.jpg


20111105_12_42_4.jpg


20111105_09_48_3.jpg


20111105_09_45_1.jpg



greets Carsten

PatrikE
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Re: My First Quadrocopter Design

Post by PatrikE »

2S vs 3S...

With 2S the throttle position for hovering will be close to full throw.
With 3S the throttle position for hovering will be around midstick.

2S will give wery little spare power to compensation.

/Patrik

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Th0rsten
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Re: My First Quadrocopter Design

Post by Th0rsten »

Nice FC. Did it almost the same way. :)
Used an Arduino Mini.
BTW: Do only connect 1x ESC to supply 5V and leave the others unconnected.
Attachments
shield.JPG

zviratko
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Re: My First Quadrocopter Design

Post by zviratko »

Th0rsten wrote:Do only connect 1x ESC to supply 5V and leave the others unconnected.


is there some practical reason apart from saving pins?

cardboard
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Re: My First Quadrocopter Design

Post by cardboard »

If im not mistaken the reason for only connecting one esc to power the arduino is a safety issue. Having multiple power supplies connected together can lead to problems with voltage difference across the escs, one esc trying to power another one, possible ground loop or similar effect maybe?? I don't know of any other application that calls for more then one power supply unless they are somehow regulated and kept electrical separate from one another.

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

@PatrikE: I think you can't write what you did in general. It's all depending on the ratio between weight and power. Of course I see your point, but sometimes less weight is better than more power.
@Thorsten: Thanks for the tip. I'm used to connect only one BEC in my planes as well.

Kind regards
Carsten

KaiK
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Re: My First Quadrocopter Design

Post by KaiK »

I would power the Arduino directly from the Lipo, because of lower noise than ESC 5V.
Arduino should work with 3S (and you could use one or two diodes to lower some volts...)

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Th0rsten
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Re: My First Quadrocopter Design

Post by Th0rsten »

If you want to power the FC direct from the LiPo use a 7805 power-regulator.
They are quite cheap. I'm thinking of doing so in the near future.

cardboard
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Re: My First Quadrocopter Design

Post by cardboard »

I would highly avoid powering anything via the lipo directly, bec's and esc's are built to avoid causing issues and will help keep a more stable voltage. Some becs even have ferite rings etc to help with noise. Using diodes is not the normal way to drop voltage and is also not all that efficient. Becs are cheap anyway so not a huge hit to the pocket.

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

I've been in the same trouble. Thinking about those possibilities. In my first "pcb design" I included a 7805, but then i decided to simply use the BEC-Voltage, because it was easyer to build.
I think the current for the Arduino and the sensors is quite small. So there shouldn't be any serious load on the BEC.

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

A few minutes ago my brother mailed me a picture of the middle part of the frame.
Seems if I'll be able to make my first test at the weekend.

tovrin
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Re: My First Quadrocopter Design

Post by tovrin »

I've had my arduino powered straight off my li-po all along. the arduino can handle up to 13v without issue.

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Th0rsten
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Re: My First Quadrocopter Design

Post by Th0rsten »

The spec of the Arduino says 9V max. At least on the plain Mini I'm using.
You would get a problem with 13V on the servos for the camera pan and tilt.

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

I'm thinking about using the BEC of one of the ESCs for the Arduino and the sensors and using another BEC for the servos.
This should keep the load to the BEC quite small. Do you think this is possible?

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

I tried to attach a PDF file including a 1:1 top and side view of my design, but pdf is not allowed.
So I converted the PDF into a GIF, but the GIF was to big. Finally I resized it and got the file attached.
Attachments
Quad_a-sample.gif

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Th0rsten
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Re: My First Quadrocopter Design

Post by Th0rsten »

At the moment I'm powering my quad from one 2A BEC.
FC, RX and 2 Servos for camera Pan & Tilt. Works quite well.
5V @ 2A are more then enough for that.
I see no problem using a separate BEC for the servos.

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

It's truly sad, but the truth. This frame is to weak for the tests of a beginner. In the outer area where the motors are located it is made only of CA in the meantime. Started a new much simpler design based on Alu yesterday.
I'll keep you informed.

doublemind
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Re: My First Quadrocopter Design

Post by doublemind »

I builded a much more robust design.

379739_162961260469709_154508934648275_256347_2096338439_n.jpg


750mm distance between the axis. 870g total weight.

mabaka
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Re: My First Quadrocopter Design

Post by mabaka »

cardboard wrote:If im not mistaken the reason for only connecting one esc to power the arduino is a safety issue. Having multiple power supplies connected together can lead to problems with voltage difference across the escs, one esc trying to power another one, possible ground loop or similar effect maybe?? I don't know of any other application that calls for more then one power supply unless they are somehow regulated and kept electrical separate from one another.


In general you should choose one ESC 5V output (say, the one with highest output) and supply your board from it.

There is one situation in which you can take advantage of two or more ESC 5V outputs. If your board has several 5V supplies (5V in the set of three pins connectors, external supply, USB connector, etc), probably internally they are connected through Schottky diodes, as in attachment. So you can connect two ESC's and add some reliability: if one ESC 5V fails (and the rest of that ESC still works), the electronics will be supplied by the other ESC, and you will keep flying.

This must be verified with a careful visual inspection of the board. The Crius AIO is one example.

5V selection with internal diodes
5V selection with internal diodes

KhoaNgo95
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Re: My First Quadrocopter Design

Post by KhoaNgo95 »

I would recommend powering the FC from a separate UBEC (not linear) because from the ESC you can have some irregularities sometimes, and you'd want to avoid taking risk with that. From the design point of view, what is the purpose for the frame size? 700mm~ is quite big and they are usually that size to accommodate for the prop size.
More voltage means less current, and that means the system is more efficient, that is always the case. Unless your design requires 2S specifically, 3S should be the goal for most designs as they are the norm of quadcopter of that weight.
Ecalc is an excellent tool to sort of map out your design and have a feel for it. You should take all your measurements and predictions and put it in the ecalc, after that, design a system that could hover with 45-50% throttle. In reality your quadcopter will hover at 60-65% because of the 20% head room MW code has. Now if you chose 3S, hypothetically, the hover of a design could've been at 55%, that is perfectly fine. However, if you chose 2S, it could have been at 70%, which make the quadcopter very sluggish. If you're not interested in acro flying, then your build should lean toward flight time or a mix of both. For each type of build, there are a lot of specific rules that govern their characteristics. Don't dismiss the design as not acro and build something that is very limited in all sides.
The closest build I have right now that is similar to your would be my Flyduino Warthog build, an acro build. 615g AUW, 7-14 mins flight time, hover at 40-45%
ZH0U0337 (1).jpg

ZH0U0273 (1).jpg

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