I'm building a somewhat complicated robot that requires MANY control inputs,
controlling 25 servos and 2 motors with 18 analog sticks and a push button via wifi.
It needs to have almost immediate response time and facilitate very smooth motion.
Which arduinos and addons would be best here?
5v servos and the project needs to remain very small.
with 18 analog sticks
What is an analog stick?
So 18 joysticks then.
You will not find an Arduino with that many inputs so you will have to use multiplexing and port extenders to get what you want.
Also 25 servos is a lot, not so much for the control but the current requirement will be very big and that will require a big battery.
So look at a Mega and a multiplex shield. However I would guess that this project is a bit beyond your present skill level.start small and build up.
I have experience building RC aircraft and programming and I've worked power supplies exceeding 10kw.
I just needed a nudge in the right direction here, i figured this would be the place to ask.
Two Adafruit PCA9685 breakout boards could control the 25 (<=32) servos.
Harware control, so the Arduino is only used if the servos need a new position.
18 joysticks means 36 analogue inputs.
Three of these boards (3*12) might do.
Could add another one if the joystick switches are needed.
What kind of motor?
Leo..
These are the motors i have,
http://www.canadarobotix.com/hitec-digital-servos/1213-hs-5485hb
I had my eyes on an adafruit set up but i wasn't sure about it.
Thats why i'm here 
"controlling 25 servos and 2 motors"
You posted a link to a servo (found a listed stall current of 1.2A for that one).
Asked about the 2 motors.
Leo..
Sorry i read servo for some reason, i haven't decided on a motor yet, i was going to select them once i had fully decided on the rest. They aren't crucial.
I'm trying to picture a human managing 18 joysticks, or 9 humans doing so in a co-ordinated manner.
Is there any reason why the 18 joysticks and their associated servos should not be controlled by a number of completely separate Arduinos?
That would be much simpler than trying to join everything together.
...R
it's an art project of sorts, it needs to have 18 sticks on one arduino. and the button. imagine a robotic puzzle game.
AshenBaroque:
it's an art project of sorts, it needs to have 18 sticks on one arduino.
Why?
Nobody can move 18 joysticks at the same time.
In what way is the action of the different servos related to each other?
...R
Those joysticks also have a push button action - that'd be another 18 digital inputs if used.
Some more random thoughts after reading this, some more info on the actual project would probably make things a lot clearer.
Oddly it all doesn't really add up: 18 joysticks * 2 directions = 36 movements, but there are only 25 servos and two motors.
Or if using only one direction on the joysticks, that'd leave lots of servos without controls, unless you have a few where two servos are controlled together.
Also how is the control planned to? The joysticks will always fall back to the mid position. Push joystick one way and the servo starts to slowly turn that way?
18 joysticks for one arts installation, when there are four people playing with it that's going to require some good control/design to prevent stuff running into one another and breaking or simply getting entangled or whatnot.
Also it's going to some way for the people to know easily what their joystick controls. Having to figure out what your joystick controls when there are another 8 or 10 things moving at the same time within what sounds like a quite complex installatino is not easy.
Why do you criticise an art project? The effect of moving any joystick, alone or together with others, can be mapped to any movement of any number of servos.
And as Robin2 said, and what I think as well, there is no requirement that all this has to be done by one Arduino. But if required, a master controller can act as "that" unique master Arduino, with the other slaves extending its I/O capabilities.
Also it's going to some way for the people to know easily what their joystick controls
I have found that this sort of disconnect between a control and what it actually does is almost obligatory for art projects.
Not sure if this is intentional or the fact that it is an artist doing the design and not an engineer.
Or it could be there by intent, to increase the sense of discovery when the patron ‘figures out’ the control.
Ok, it's a game. i have 18 control sticks and two sides. each side attempts to use the controls provided to move an object through a series of complex actions.
There are several "arms" that have overlapping controls, so it is possible to interfere with the other person by sending a mixed signal to their arms. The "return to zero" effect on the arms is intended as it requires finite control of the sticks to maneuver the arms.
The idea is to push my hardware choice a bit, maintaining a small profile while being complex enough to merit some time spent by guests.
None of the speculation really helps, this is a help forum not a "Decipher the OP" forum.
Thanks to the few people that did help and refrained from insulting or demeaning.
AshenBaroque:
None of the speculation really helps, this is a help forum not a "Decipher the OP" forum.
Thanks to the few people that did help and refrained from insulting or demeaning.
Strangely enough what you call "decipher the OP" is an important step in trying to help the OP. Have you never tried to help someone yourself?
And who has been insulting or demeaning?
Ok, it's a game. i have 18 control sticks and two sides. each side attempts to use the controls provided to move an object through a series of complex actions.
There are several "arms" that have overlapping controls, so it is possible to interfere with the other person by sending a mixed signal to their arms. The "return to zero" effect on the arms is intended as it requires finite control of the sticks to maneuver the arms.
Now that we have a better idea of what you are trying to do maybe we can make some progress.
I confess I am still unclear about the intended usage of the 18 joysticks and why they can't be connected to several Arduinos. Maybe you can provide a description of how the game is to be played and a diagram of the final product.
...R