MultiWii

Hi All,

I would like to build a quadcopter based on multiwii software, but I would need to modify it in order to add features, like triggering actions such as starting / stopping a camera, transmitting some data, executing routines in the code to modify the behavior, the flight plan, etc…).

I see two ways to do that:

1. Have an extra arduino board on the quadcopter to recieve XBee signal and either command the multiwii board or trigger special actions.
2. Use an existing multiwii board with a modified code to recieve XBee and some extra I/O pins to serve my purposes.
3. Use an arduino board equipped with sensors

The first solution adds an extra 45 grams (Uno + XBee) and requires to figure out how to emulate a "standard" reciever to control the multiwii.
The second solution requires me to either find a suitable commercial multiwii board.
The third one requires that I find compatible sensors to build the setup from scratch.

What would you recommend?
I would like to have quality sensors for stability (without too much noise – I read wii sensors are a bit noisy) and I would like to avoid having to buy wii accessories.


Many thanks for your advices,
Julia

I'd start with option #1. This allows you to keep the code you are writing seperate from the MW code that is controlling the copter.
Then after you learn enough and have things working you can re-evaluate how the overall code should work and if the added code can be intergrated into the MW code to run on the MW FC board.

I recommend using a MW FC that has an Atmega 2560 processor since this one has multiple UARTs and much more memory space.This will allow for many more options and the finial code will most like fit along with the MW code.

You do need to do lots of goggle searches and reading.
Good luck and have fun.

Thank you for your reply. I thought as much. Not that I am afraid of programming (I have a lot of experience with various microcontrollers). The issue is that I have a hard time finding any documentation about how the multiwii firmwares receives radio imputs. If I want to replace all the receiver code with my own, which functions should I call to raise, lower, tilt, etc… the copter?

I have been googling for a week before registering here. I like to do things by myself. But now I recon I need help.

You then need to fist study how a multirotor copter is controlled from an RC radio system. Two sticks of two axises each. Each axis controls: Roll, Pitch, Yaw and Throttle. The stick position is encoded into a pulse and sent by RF carrier to the RC RX. Then pulses are then output on the RX's channel pins that go to the FC board.
You need to do a lot of google searches and a lot of reading and then some coding and experimenting as I explained in your other thread on the subject.

Thank you for your reply. Please, could you just help me with : FC, TX, RX, RC RX abbreviations so that I can search for them?
I do google a lot. Sometimes, a little help can make a big difference in terms of search times. It's hard to know what to search when you get a lot of coded language. And being a girl doesn't help either in a world "reserved" to boys.

FC = Flight Controller. This is the board (hardware) plus the Firmware (code loaded) that take the signals from the RX and from the sensors (Gryo, Accel, etc) then outputs to the ESC/motors.
TX = Transmitter. This is the RC radio take you hold in your hand and has stick to control the aircraft.
RX = Receiver. This is the RX radio that receives the RF signals from the TX.
RC = Radio Control, it is the generic term for hobby grade radios (Tx & RX) used to control model aircraft.

Hope this helps and Go Girl, these toys are not meant for only us boys.
Keep the question coming.

Thank you for your reply I understood all that from the other post .

On this thread, I would like to focus on the hardware. As you can se from my other question related to RC and TX module / FC communication, I am leaning more and more towards solution #1 or (probably) #2.

I haven't decided yet where to buy, but I have seen many different setups such as:

Crius AIOP
MultiWii PRO Flight Controller w/MTK GPS Module
Multi-Rotors MultiWii CRIUS AIO Pro V2

etc…

I would like to have a working hover mode, gain altitude, have a GPS and low noise sensors. What would you recommend (I can buy only one FC) ?

Thank you for your help !

Now you got me since I did not fly with Baro, Mag or GPS.
The CRIUS boards have a good reputation so maybe one of them.
Google each of them and read reviews/issues then make a choice.

Julia wrote:Thank you for your reply I understood all that from the other post .

On this thread, I would like to focus on the hardware. As you can se from my other question related to RC and TX module / FC communication, I am leaning more and more towards solution #1 or (probably) #2.

I haven't decided yet where to buy, but I have seen many different setups such as:

Crius AIOP
MultiWii PRO Flight Controller w/MTK GPS Module
Multi-Rotors MultiWii CRIUS AIO Pro V2

etc…

I would like to have a working hover mode, gain altitude, have a GPS and low noise sensors. What would you recommend (I can buy only one FC) ?

Thank you for your help !

As Waltr mentioned, Crius have an excellent reputation for quality boards. I have the Crius SE V2.5 (328 based) in my plane & the Crius AIOP V2 (AtMega 2560 based) on my X525 quad. They are both excellent boards, but if you want GPS and comms you need the AIOP V2 which has 4 serial ports, 12C port and loads of direct input/output ports that you can configure anyway you like. You mentioned radio links and controlling camera. This is a cinch with this board. Just plug 3DR radio into spare serial port(just bought a set for $40) & connect Cam Trig to output 46. Outputs for camera gimbal control are also there. Here is the best info I have seen on crius AIOP V2 http://www.multi-rotor.co.uk/index.php?topic=1435.0
This guide is for MegaPirates (APM on Crius) but all connections are the same as is the setup.
I would also advise getting an external Mag board or Ublox 6M GPS with Mag that can be mounted on a mast http://www.ebay.com.au/itm/181503510142 ... 1439.l2649
To use ext Mag just cut the pads provided on the AIOP V2 & mod Config.h and Def.h to enable. Search forum on how to do.

Thank you very much, both of you for your replies. I will take the Crius AIOP V2 with the ext Mag and XBee modules.
Now I need to figure out which motors / ESC / propellers to take.

Julia wrote:Thank you very much, both of you for your replies. I will take the Crius AIOP V2 with the ext Mag and XBee modules.
Now I need to figure out which motors / ESC / propellers to take.

Unless you already have the XBee modules I would go for a set of 3DR radios instead. These are available in 433 or 900Mhz so don't affect RX. They also have range up to 1Km with supplied aerials or several Kms with high gain especially with 900Mhz.

I already have the XBee pro modules, but I am interested in long range actually. So 3DR radios could be nice. I think regulations only allow me 433 MHz. I might have to buy a license, but I am unsure.

Which RX would be affected? The RX is the reception of radio command?
Can I use 3DR both for controlling the copter and getting data from the camera?

Julia wrote:I already have the XBee pro modules, but I am interested in long range actually. So 3DR radios could be nice. I think regulations only allow me 433 MHz. I might have to buy a license, but I am unsure.

Which RX would be affected? The RX is the reception of radio command?
Can I use 3DR both for controlling the copter and getting data from the camera?

XBee is 2.4Ghz & so is your RX (radio controlling copter). Not nice to put a TX next to RX on same frequency. If you are in USA the licence free band is 433Mhz so antenna is much larger than 900 for same gain.
The 3DR radios are serial data only http://www.ebay.com.au/itm/3DRobotics-3 ... 3ce568a4c6 & now half the price I paid!
If you want video link you need a set of these http://www.aliexpress.com/item/Boscam-F ... 71942.html

Thank you for your reply. I did some more research. TX and RX is transmission and reception, to control the copter. Since I plan on using XBee to control the copter (allowing me to have as many channels as I see fit, within reason), there won't be any interference between XBee and RX, right ?

Many thanks for the useful links. I spent the time looking a them and doing some more googling. Currently, I am at the motor / propellers selection stage. Ideally, I would like to have around 2.5 kg thrust total, on 4 propellers. I am inclined towards getting a lift at about 30 % power, so that I have room to add cameras on the copter.

Julia wrote:Thank you for your reply. I did some more research. TX and RX is transmission and reception, to control the copter. Since I plan on using XBee to control the copter (allowing me to have as many channels as I see fit, within reason), there won't be any interference between XBee and RX, right ?

Many thanks for the useful links. I spent the time looking a them and doing some more googling. Currently, I am at the motor / propellers selection stage. Ideally, I would like to have around 2.5 kg thrust total, on 4 propellers. I am inclined towards getting a lift at about 30 % power, so that I have room to add cameras on the copter.

You lost me. You say you are going to use XBee to control copter. Isn't XBee just a 2.4GHz serial link the same as 3DR but with less range?
I use 3DR on my APM quad for two way telemetry (I can see all fight parameters on Mission Planner running on my tablet plus program Missions , change PIDS etc).
I don't control quad using 3DR but by dedicated Lemon DSM2 Spektrum compatible 10 channel receiver which also has failsafe on all channels & Spektrum DX7 TX.
Some do control quad via 3DR radio but you need special transmitter & modules to achieve this & range/interference rejection would not be as good..

Re the motor/props. If you are looking at hover @ 30% throttle with 2.5KG thrust then you will need some high power motors & large quality props. There s a calculator that will work this out for you http://www.ecalc.ch/ as well as http://personal.osi.hu/fuzesisz/strc_eng/
What size is your frame & proposed battery?