RC India

as all know that in a quadrotor u need to vary the relative speed of motors.........can anyone tell me how to vary the speed of motors wirelessly??
which microcontroller can be used??
which remote control to use??

dude first stick with a single thread! it will easier for people to respond to you!

u already started this today!
http://www.rcindia.org/self-designed-diy-and-college-projects/final-year-project-quadrotor/msg9358/?topicseen#msg9358

The motor speed is varied by PWM. For a brushless motor, it is more complicated especially for a sensorless design. You are much better off buying. Else building a brushless controller should be a project by itself.

Using a standard remote controller and receiver will be easier. If you want to build a controller yourself or want to control from a PC then I'd suggest using a maxstream module for RF link. It is available in India easily.

Which microcontroller to use depends entirely on what you want to achieve. You could also look at splitting the job across multiple microcontrollers. First thing I look for to select a  uC are the peripherals that are most suitable for the jobs at hand.if you can offload most of your work especially jobs that require specific timing like i2c, UART etc to peripherals that makes your job much easier. Also look at using counter and timers that could offload the pulse width measurement and timing tasks. This type of approach will leave the most processing power free for your use. Look at  the ATMEL and PIC range to find one suitable to you. I like ATMEL better not just because of the architecture but also  because of gcc support. You could also look to MSP430 series from TI. Since it is a college project, you should get good support from them. There is a huge amount of information on all these on the internet, start digging :)

What abt PIC18F4431........We are planning to use that microcontroller......do u have any views abt that.........

Looks promising, but without knowing much about what exactly you are going to do it is not possible to say if it is suitable or not.

Before buying it, you need to do finalize your requirements. Decide what all functions you need the uC to perform and what parts you'll buy first. I'd recommend to start with using a proper RC set and BL ESCs. Later you can change to your own controller and RF link or split your team and have one group develop the control software and RF link in parallel.

Once you decide on your requirements you need to start on firmware. Start with listing out all the parallel tasks you need to perform. For example, measuring PWM stream from the rx could be one thread. Another could be driving the servo pulses to the ESCs. Yet another for communicating with your accelerometer/gyro. And another for mixing inputs from rx and gyro and update PWM duty cycle for servo. See how you can use peripherals for these. This PIC has 4 PWM outputs you could use. Also you could use PWM capture for rx pulse stream.

Once you have identified the functions see how you can perform these tasks in parallel. Some functions could be interrupt driven, while others might need a continuous loop in software. You could also interleave multiple tasks in a loop. Try to avoid timing critical tasks in interleaved code. It cannot be avoided sometimes, use it as last resort. Implementation of all this is very specific to the uC you choose, so read the datasheet very carefully before starting.

PIC uCs often multiplex I/O pins/counters/timers for multiple functions. Watch out for conflicts when you are planning the firmware.

Also don't forget to use watchdog timer. Plan the code initially itself such that a watch dog reset would regain control of your aircraft seamlessly. ie try not to have too much pervious state information for proper functioning. Remember the Spektrum reset issue.

Which compiler are you planning to use ? I suggest using a C compiler than coding in assembly directly. Quite often these compilers do a better job than you do at optimizing. However do keep checking the assembly code it generates and see if it is giving you the most optimal code. If you can think of a better way than the assembly code generated, do not jump and insert assembly code. Often a subtle change in the way you write the C code will give you the assembly code you want. Keeping the code in C will make your life a lot easier later in the project when you need to tweak here and there.

The QEI module looks interesting, I haven't seen this before in a uC. Work has kept me away from these hobby stuff for some years now and looks like I have missed some progress in uCs. Are you planning to use this module ?

BTW, which college are you from ?

I am frm TKM COLLEGE OF ENGINEERING,KOLLAM,KERALA.

Can v  vary the speed of motors without using ESC??

If you are using brushed motors, you could use the PWM outputs. For brushless motors, you are better off using an ESC.

Brushed motors are heavier than brushless motors for the thrust they can generate. Also the efficiency is less in most cases.

Can you provide me with any link or some resources which can help me in programming the PIC18F4431??

Haven't touched a PIC in many many years :(  but a Google search for "PIC18F4431 sample programs" seems to bring up tons of useful links.

http://www.pic18f.com/

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en020394

http://home.earthlink.net/~davesullins/software/pic18f.html

and many more.  Hopefully some of these will be useful to you  :thumbsup:

And these are more relevant to your cause.  Probably a little too relevant to put you in the league of plagiarism ?

http://www.st.ewi.tudelft.nl/~gemund/Courses/In4073/Resources/RA.pdf

http://me.columbia.edu/seniordesigns/2007/QUAVe/FinalReport.pdf

Thank you very much..........

Actually i have taken the columbia universities project as my references but since they have carried out the project in 2007 the components they have used is no more available.......thats y i palnning to use new components  but there is one problem ....... i have got free samples of accelerometers as well as gyrosopes from analog devices but the thing is that they have send me SMD devices so in order to use them in my project i need the evaluation-board for the gyroscope which are still under production .the accelerometer is ADXL213 and the gyroscope is ADXRS613..........
Do you know from where can get the evaluation board of the gyroscope in india??

Does anyboby know how to transmit video signals??
I am planning to incorporate a video camera on to my quadrotor..........

To transmit video signals, are you planning to build or buy ?

i am planning to buy ..........how can i implement it..........what will b the hardware requirements??

If you are planning to buy, just search for "FPV" in this forum, and you will find many threads that discuss equipment and setup for the same.

Does anybody have any idea of gyroscopes in depth??
if in a gyro it is said that itz output is +-150degrees/sec  then what does it imply??

Does a gyro having +- 150degree/sec and another gyro +-300degree/sec made equivalent or something like that??

The number expressed in "degrees per second" is the ability of the gyro to detect how fast its is turning.  So a gyro with a 150 degree per second can detect a turn of 150 degrees in a second.  In other words, if you want to detect a full 360 turn reliably, the turn has be done in over 2 seconds (360 / 150 = 2.4).  If you did a full 360 degree turn in say 1 second, the gyro will NOT be able to detect that correctly.

Now a low "degrees per second" is not necessarily a bad thing, especially for what you are trying to do.  Some gyros have two modes, one with a higher degrees per second, and one with a lower degrees per second.  The lower one is also known as a "high sensitivity" mode, where small changes in directions/turns are detected with better accuracy.  Remember that the more distance you travel, even small differences in direction gets amplified, so accuracy is more important in most applications as compared to detecting more "revolutions" in a shorter time.

See the link in the last post on this thread : http://www.rcindia.org/servos-gyros-and-all-electronics/gyro-modes-normal-and-heading-hold/

So for my quadrotor can i use a gyro havng +-50 degree/sec over a +-150 degree/sec gyro??

There has to be a trade off between turn detection rate (degrees per second) and sensitivity, right ?  I am not sure what that is for your application.  Why not 10 degrees per second instead of 50 degrees per second ?  ;)

It boils down to how much/fast of a turn happens in real life that needs to be reliably detected, for your application. 150degrees per second looks like a happy medium (for an RC type of application).  Just a guess though at this point, without adequate data points !

The important thing is to experiment with what you have, and then think about changing.

I suppose you are using gyro for stabilization, don't think your application needing insane piro speeds like used by some rc heli fliers. 50deg/sec should be plenty for this.

I was looking at it from the view point of "what are the chances of the aircraft tilting 50 degrees in a second".  That sounds possible, while 150degrees sounds less possible.  So wouldn't 150 be a better choice than 50 ?

Of course there is counteraction as soon as the shift begins, but how long before everything reacts to put the stabilization motion in place ?

Don't disagree with higher the better logic. I was thinking that even 50deg/sec is a drastic change for a quad rotor platform. Consider that for this application you will be starting with a platform that is inherently as stable as possible even before you add stabilization. It sounded like he already has a gyro with 50deg/sec and wanted to know if that would be sufficient.

What he has is -+150 deg/sec.  Should work fine ! 

Not sure why the question about 50deg/sec....  availability of more ?

i just asked this question in order to get an idea abt gyros output...........i am havng +-150degree/sec gyro.......is it enough for my project.......
what do u feel abt that??

Can anybody provide me with some resources that would help me in developing the 'stabilization part' of the programming in a quadrotor??

Now you are going where I don't have any practical experience. The standard way is to use a PID loop for the control system. The problem with this is I'm not aware of any way to come up with the coefficients other than by experimentation. From what ever simulations I have played with, it is not very difficult to get a reasonably stable system just by judicious trial and error tuning. If you are looking for the most theoretically optimal solution, then I'm clueless how to get there. If I were to do it, I would just tune it by flying it. If you have RC control and you can switch on and off the stabilization, you should be able to do it safely. You might also need Kalman filtering for the accelerometer signals. I'm getting outta here before you ask about Kalman....

Probably you could take a look at the paparazzi code (open source). You might be able to adapt the Kalman code from there.

I have shortlisted two motors for my quadrotor........there urls are pasted below.......
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=4700&Product_Name=hacker_Style_Brushless_Outrunner_20-22L
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9996&Product_Name=ADH30S_Micro_brushless_outrunner_6100kv

Please suggest if any other good motors are available .........itz very urgent.........

The two you have listed are vastly different in terms of everything (KV, current, weight, size).  Are you undecided, so you are getting both ?

Remember that selection of motors start with the AUW of the intended aircraft.  Are you basing your selection on this ?

The total weight of the quadrotor will b close to 1800gms.
So which motor should i use??
Do u have any suggestions??

Hmm... here is where my lack of any sort of direct experience with these things show up  :(

Usually, there are rules of thumb like you have to have around 400watts power for each 1000grams of AUW.  But since this is a quad-rotor, and there are 4 motors sharing the load, my guess is that you should be able to go with less. I am not sure if that is 25% of what is normally required, so if I were you, I would over engineer it a bit.

My piece of advice on the microcontroller. Check out

http://arduino.cc

It is a great place to start on an atmel based microcontroller project. There is lot of reference projects and libraries for servo control, i2c, pwm, mems sensor interfacing etc. A development environment and bootloader support coming from an MIT inspired project project. And a great coding metaphor to work on. Also, you have a number of clone designs to work with and a really great open source community.

http://diydrones.com/profiles/blogs/ardupilot-home-page

The above link shows them using the same dev platform for an autopilot for DIY drones. They have deployed advanced logic like Kalman filtering and prediction to get the autopilot working.

The boards for dev are available in India from

http://ashwin.venkat.googlepages.com/arduino

A great advantage, the whole thing is OpenSource tech, including various add on daughterboards etc.

In fact I used the setup to dev a transmitter. I am now planning to use the Maxstream module add on board for radio link

hi RVRENJITH,

FYI : There is loads of material at http://www.rcgroups.com/forums/showthread.php?t=1097355

Hope it will be of some help to you..!!


-Arun Reddy.
---------------------------------------
Trying to build a QUADROTOR.
Motivated by Ashish Bhatt's Quadrotor in 3 Idiots.

http://arduino.cc

hey now arduino available at cochin

please help........

it has been along time since i have been searching for the brushless motors and the ESC in india.
Now since there no time i am planning to order these motors and the ESC from the US.
and i am using a 10*8 propeller.
The motor is http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=5691
The ESC is http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=5691
will these combo do the work.
the total weight of the craft is supposed to be around 1600 gms.

Is there any relation between the size of propellers used and and the voltage of the LiPo cell used??
If the propellers used are 10*8 ,then cant be a battery with 11.1V be used??

Yes is the simple answer  and  the key to understanding it lies in  the basic fundamental of a DC Motor  which is high school  physics .

Speed and torque  in a DC  Motor  are inversely proportional .

In the case of a BLDC Motor  KV = RPM/V

So now can you understand the relation between prop size and  voltage if the prop is considered to be the load .
Sai

This has been discussed many times before, but to summarize (again!) :

1.  The motor prop combination is determined by the weight of the model and the type of flying.

2.  You have to choose a prop that is in the list of supported props for the motor (determined by the KV rating of the motor mostly, which in turn translates to the rpm at which the motors turns). 

3.  The load rating of the motor (as measured by the current drawn in amperes) by a given motor/prop combination determines the speed controller to be used, and that in turn determines the battery voltage (lipo cell count).

Now based on this, you will realize that it is not easy to give a "yes or no" type of answer to your question.  Unless we know what motor and ESC are being used. 

You have posted the motor link twice above instead of the ESC link.  And for that motor, the recommended props are 11x4.7, 11x3.8 and 11x5.5.  A 10x8 does not look at it is suitable, if you are asking about that motor. 

Plus the ESC still needs to be clarified, which has a direct impact on lipo selection.

You have to be careful with the prop selection, or the results can burn your pocket !

in a quadrotor four propellers are used out of which two are pusher type and two are tractor type.
what should one do if the two variants of the suggested props for a given motor are not available??

i am having so much doubt regarding quadrotor because i have learned about the quadrotor from google and referring to several threads.

Now i am really confused.I have taken a project done by the columbia university guys as my reference and till now i was taking my steps according to that and i have ordered a 10*8 propeller set.I have already spent a lot of money for getting the gyroscopes and accelerometers.
Now after your reply i feel that i made many mistakes.

Can you suggest me the brushless DC motors,ESC,propellers and the battery to be used and also the place from where these stuffz can be brought(from india)

Please help me out its very urgent.

To be clear, I did not say a 10x8 will never work. It needs to be paired with an appropriate motor and ESC, that's all.  If you are following an earlier setup, please follow it (as close as you can ) for everything.  So see what motor (how many watts and how much KV rating) they were using, and find the closest one for your project.  Similarly for the ESC, see what was the amps rating.

I am not sure at all on what is the thrust distribution in a quad-rotor (no experience at all).  Please see what the Columbia guys did (basically, what was the AUW of their hovercraft, and what wattage motors they used), and that should give you a fair idea of what type of motor you need to get.  Once you know what you need, you should be able to find the equipment locally.

Renjith ,
The number of Quad Projects going around in India are many  that we know of itself  .
The fundamentals for set up selection has to be understood  and not  copied letter to letter word to word .
We have the set up and the 3 blade  props in matched  pairs available for them and many  students including those from IIT's buy these from us  for their projects .
Its the motor that is critical  that has to determine the prop and not the prop determining the motor.

As Anwar says  it is not that the 10 x 8 will not be suitable but since you have  bought the prop you now have to  settle on the motor to spin that prop .

But be aware that you have to have sufficient stock of the props  if you are going that way as the likely hood of breaking  them on testing is high.
Otherwise the better is to keep those you have bought as spares and redesign  a motor, prop , battery combo over again .

The electronics that  goes into it will remain the same irrespective of the power system hence that is not a waste .

So cheer up  nothing to get confused about , relax  and think rather  than get worried  , from what you say it looks that  you are  confused onlly because of the props you have bought  which  actually is the least of the problems.

Sai

you can buy from rotor sports chennai.
buy online from rotor.co.in

im from pune n doing quadrotor as my final year project.Im ordering req. components from rotor.co.in chennai. plz somebody tell me how many days it will take for actual delivery after payment?
 

3-4 as per my experience

i m trying to build quadrotor almost since 2 years,

 to read my full experience just goto

 http://pankajwasv.blogspot.com/
and you have come to right place,rcindia has all you need

i have made the structure and had a mini lift off.........but its using a remote control....
i need help in programming out the PID controller for the quadrotor......help me out.....

this may help
http://quaduino.com/

i have made the quadrotor project done by columbia university as my reference.
and we tryed testing  the motor based on the circuit provided by them and the result was that i blowed up the signal generator of my college.
and then carried out the mini-lift by directly connecting the ESCs to the receiver end and the test was successful.
am having two dual axis accelerometer-ADXL213
and one gyro-ADXRS613 and also PIC18F4431....now how should i alter the circuit,since the columbia guys used brushed dc motors.
how should i connect the ESC outputs to the microcontroller .

u can see the attachment which help u to connect microcontroller to esc.

cant the interfacing carried out without using mixers??

am already having one gyro(ADXRS613) and two dual-axis accelerometers(ADXL213) ......so how can i do the interfacing.....help me out..

Read about Arduino platform... Programming it will be very easy as it is based on C...

you need atleast 3 gyros for the 3 axises too

are the quads come in rtf condition in India ?

Hi Prateek, You can contact Mr.Arvind of http://rotor.co.in/ , Hope he can help in getting a RTF Quad Fliers.

- Srihari

 I want to build a simple remote controlled quadrotor as my final year project.actaully des days i am very determined and crazy to do dis project.can  anyone pls  help me??what will b the total cost??so dat i can arrange my budget 4 dis.I need sum initiative procedure from experienced personnals...it's urgent....

If you read quad related threads on this forum, the first question is how much you want to build yourself using PICs etc (soldering your own microcontrollers and sensors) and how much you want ready-made (just adjust some software, put things together and do flight tests). 

i too got quad , codded by my self.. rock solid in the air , flies up to 40 min in normal flight and in acro 30 min

very simple hardware design and very very simple software running dual layer pid loop for rock solid stability

any if interested pls contact me through mail vultureb2@gmail.com

hey guys !! i m designing a quadrotorcraft so can anyone plz tell me how shud i start and where would i get the propeller for anticlockwise rotation ?

Welcome to RC India :)

Looks like you also joined and posted a quad related question in 10 minutes ;) There is much discussion about quads here, including offers from people who professionally guide people building quads.  Please "search" the forum, that should give you a good head start.

I am merging this question into one of the quad related threads.

okay i got it. tell me. If anyne Specialist in Quadcopter here then please tell em ATMEL AT89c51 Controller is okay for this ? can we built this quadcopter by using it ?  Please tell me . ii have to make decision for this.

No, it cannot be built using that series of micro controller as it doesn't have 16bit timer nor buit in adc port and Low MIPS all of which are crucial in controlling of quadcopter. Would suggest Atmega architecture with atleast a 32k memory ideal.

....And if you're familiar/experienced with u-controller programming, you can go for STM32 processor. It outperforms all these 8-bit processors and gives you excellent results. Debug and flash tools are readily available too.

But I know programming to make it . If i start to do work on it then Is it seems possible ? because of i have that subject in last year so I have to use it. Is it possible ? or not ?

AT89C51 For To make Quadcopter.

Iff possible then tellme from where how i start to place order for components and Make the Model.