on quadracopter

[anir_n]

hi,
I am making a quad roter flying robot..i have understood the takeoff technique but not able to understand how will it move forward backward left and right....the copter has to fly to a minimum hight of 30 m ....is it possible.... anybody help me with this.... and i want some assistance for making it autonomous...  i.e. what all things i can make autonomous in it....
thankx

[TrickyNekro]

Look, I have some ideas on making a helicopter full autonomous... And I mean GPS guidance and such...
Still I lack some sensors (gyroscope)  and three servos (fuck they were back ordered!!!! aaaa)...

You need quit a knowledge man... But I can help...
Please, give me more info... And I would also like to know your age...

[Razor Concepts]

Quadrocopters are extremely hard to make. I would suggest starting of with buying the Silverlit X-UFO toy, modifying that, then getting the X-3d brushless quad, which you can add GPS and other autonomous goodies. Also knowing how to speak German will help since all the pioneers in quads come from germany    Projects like these arent month-long projects.. or even year long. People on www.rcgroups.com (where the majority of quad builders can be found) have spent about a year and half looking up the german microcontrollers and such, and so far people have only managed auto stabilization, GPS position hold, and altitude hold. No autonomous yet, that is extremely dificult. Also if you dont know how to fly an RC helicopter, I suggest you do, or else you will crash your quad. RC helis are the hardest RC vehicle to learn on, since they are basically designed to be unstable. You need a BIG commitment to make a quad... so be prepared.

Also Nekro ordered servos for the quad? Quads dont need servos to fly, only 4 motors... no mechanical motion needed. Not sure why you needed to get some servos.

[TrickyNekro]

Also Nekro ordered servos for the quad? Quads dont need servos to fly, only 4 motors... no mechanical motion needed. Not sure why you needed to get some servos.

I'm building a heli not a quad... that's why...
But imagine building a V44.... not bad at all.... 

[anir_n]

hey i am working on the quad which will have a camera mounted on it and from atleast 30 m above it should take pictures and send it wirelessly to the ground. i want to know about the forward backward left and right movement of the quad . as by the design i can understand that how it goes up and down but im nt able understand how it will hover around... and plz suggest me which kind of wireless comunication system.... 

[anir_n]

hey i am working on the design but the problem is with the the wireless communication... i am new to it and don know any thing about it.... i want to interface it with y pc when it is flying...
i mean the control panel and the video should be there on the pc...plz help me with this....

[Admin]

anir, for video:
http://www.societyofrobots.com/robot_faq.shtml#camera_microcontroller

And for wireless communication, read up on Bluetooth, Xbee, and Easy Radio. You can find it all here on the forum/site.

[izaktj]

Also Nekro ordered servos for the quad? Quads dont need servos to fly, only 4 motors... no mechanical motion needed. Not sure why you needed to get some servos.

I'm building a heli not a quad... that's why...
But imagine building a V44.... not bad at all.... 

Will you build your autopilot or buy an already made one?

[Razor Concepts]

Why not just use hobby grade radio control? You can get nice 10 channel computer radios, they will help you dial in one part of the quad at a time instead of slapping everything together and hoping that works.

[Steve]

I'm a newbie to robotics, but have had experience in flying R/C helis. What you are asking is about the mechanics and physics of how a helicopter or quad produces forward or sideways movement. My suggestion is to go out and get some experience in trying to fly one of these by R/C yourself first - THEN think about making it autonomous. You need to get a feel for how it responds, otherwise how on earth are you going to know how to control it? They are not as simple as, "just move the right servo and it moves." These things are not inherently stable. You are constantly making many fine adjustments per second, just to keep it in a stable hover in one position, this is even with a built in gyro. You will have to program your autonomous quad to sense all slight movements and adjust them constantly. This is just in complete still air. Imagine you get a slight breeze or turbulence. Do not try this project until you are familiar with the radio control version - you will only end up frustrated. Go and fly one and you'll see what I mean.

Having said all that, I think this would be a great challenge for someone who has had a lot of experence in building robots and programming.

Steve

[Razor Concepts]

Steve do you frequent HF or CR?

For those of you that are interested here is a youtube video showing 3-servo CCPM, the type of mixing most RC helis use. For quadrocopters you will need 4-servo CCPM, basically the same as 3 but instead, the 4 servos located at every 90 degrees instead of 120 degrees.

http://www.youtube.com/watch?v=Ux1cgwBhhvM

[Steve]

Steve do you frequent HF or CR?

I have no idea what you are talking about. What are HF and CR?

By the way, the video link showed how the servos move the control surfaces, but the quadracopters I have seen use a fixed pitch and just control each rotor with a speed controlled motor.

Steve

[Orrin]

I have a little experience in making quadracopters in physics simulations and a couple video games, so I only know theory.

Basically:

One (Servo/rotor that controls pitch) == Pitch (what your gyroscope might output for pitch)
Two == 0 - One (To make a negative for the rotor on the opposite side.
The same thing goes for roll.

If your pitch goes negative, then the servo will start up, the more it tilts that faster it spins to correct this.
One thing about this method is that the rotors tend to over correct, resulting in a very shaky and out of control heli. One way to combat this is adding delta to your equation...

One == Pitch + ?Delta of pitch? (I don't know how to input this into C++)

Since delta is change over time, it allows you to react to big changes and slow down when you are stable again.

This would probably require a lot of calibration.

To get it to turn:

One == Pitch + Delta + Input

Input is whatever your RC controller is outputting or your program. It should be a round +- 20.

With the above equation, you can hold your coptor and 0 degrees and when you input a +20 it hold at 20 degrees. (so you move forward.)
[youtube]http://www.youtube.com/watch?v=Tj0Upu1SF9w[/youtube]
This video is from a video game (Garry's Mod) I made it to kind of demonstrate how you would do this.

I used thrusters instead of rotors, so its probably more responsive, but it helps illustrate how this would work.

This is all totally theory but maybe that gives you an idea of how it all works. What you plan on doing is quite the undertaking, and if you succeed I would love to see the results! 

[Razor Concepts]

Steve do you frequent HF or CR?

I have no idea what you are talking about. What are HF and CR?

By the way, the video link showed how the servos move the control surfaces, but the quadracopters I have seen use a fixed pitch and just control each rotor with a speed controlled motor.

Steve

HeliFreak, CrackRoll

The servos represent the throttle settings for the motors. Imagine if it moves up, it is throttling up. That is why Tricopters use the same mixing as the 120 degree CCPM helis.