Question on general approach/details for something more complex

Hey everyone! I'm sort of sketching out the ideas for a more complicated, long term project, and I had a few questions on this end so as to hammer out some details.

At the moment, I'm looking to combine several elements of a few more simple projects floating around the internet, to make something more complex.

Ideally, I'd like to make something with two sets of ultrasonic and pir sensors, with matching oled displays for each of bitmaps of eyes (looking left, right, and center), which will follow an object based relative to the 'head', then as an extension of that, I'd like to attach two servo or stepper motors (for pan and tilt), which may additionally be triggered as the limits of the respective sensors are reached.

This is just the beginning steps, though.... Eventually, I would like to make an arm, then perhaps legs or something for mobility, etc...

Eventually, I would more than likely use something larger/more powerful to control everything, of course, but my current line of questioning is... is there a way to communicate between more than two Arduinos at a time, so as to have multiple components executing something more complex? Or, if not, how would I go about communicating these separate actions, and with what as an intermediary? I've compared what pins I would need for each sensor (and two motors, not even taking into consideration any more), and I could easily execute each part in separate pieces simply using Uno's, but as the project grows I wouldn't want to corner myself, and there's no Arduinos with enough pins for what I need (or anything else, for that matter). But if there are better ways to approach this that I may be overlooking, I'm certainly open to those as well. Thanks!

Sorry, all of my searches on how to communicate between more than two Arduinos has been coming up short, and I've pretty much exhausted my resources trying to find a solution.

Have you tried asking in the Networking,Protocols and Devices forum? Networking, Protocols, and Devices - Arduino Forum

Networking a number of devices is their area of expertise. I've seen several projects with an Arduino "master controller" and several peripheral Arduinos but it's not something I've yet needed to do.

Steve

I haven't checked there yet, and someone also PMd me some pretty helpful links regarding this, detailing how to communicate between multiple devices using i2c (and another protocol I hadn't heard of), so it certainly seems that's the next logical place to look. Thanks!

The links are here: Gammon Forum : Electronics : Microprocessors : I2C - Two-Wire Peripheral Interface - for Arduino
And here: https://www.gammon.com.au/forum/?id=11428

I think your problem is a bit like asking "how can I make my left hand communicate with my right hand?" The simple answer is that they can't. At least not directly. But each can communicate with the brain, which can cause information from one to be communicated to the other.

The "eye Arduinos" can communicate with the "brain Arduino" which can communicate with the "neck Arduino", the "hand Arduinos", etc.

Ahh, I was looking at it just as event driven/oriented but that certainly makes more sense. Thanks so much!

Okay, with all that in mind i sat down and sketched out the details of what I'd like to do, and for now I'm gonna control each respective part from an Arduino, and use a pi as a master controller for everything (because I have a pi zero on hand anyway). When I took a closer look at just how the i2c would communicate/be set up, I saw that a few of the sensors use different communication as well (so this should simply things quite a bit). So for now I'm gonna move my question over to the appropriate thread in the respective networking/protocols and sensor forums. Thanks!