Interfacing the Arduino with Raspberry Pi 3B

Projects General Guidance
1

I'm working on a project that involves being able to control up to 20 steppers, and 10 Arduino Nano's in an organized fashion.

I've been working on this step by step and have all the code on the Arduino running flawlessly. Now I need to build out a GUI for basic control and need the benefits of integrating a microcomputer. The raspberry Pi is the best option currently.

At the moment I just need the Pi to control 2 Nano's with each Nano controlling 2 steppers.(For scalability purposes this is the configuration I'd like to go with). But I was wondering if there is a way I can use the Pi to send commands to the Arduino that would initiate the Arduino to execute code on it. Is there a good way to make these communicate in this fashion?

I've tried searching for it but all I keep seeing is people showing how to put the Arduino IDE on the Pi.

3

I should add that I am a Mechanical Engineer and have only basic hobbiest understanding of the computer sciences. It's a bit outside my normal wheelhouse. Essentially I want the Pi for the GUI and for control of the overall system. Basically 10 two axis camera controllers. For controlling those devices I'd like to still use the nano's.

In my head I feel like I just need the pi to send a string to the nano, and the nano will in turn execute code based on what it gets from the pi. Like if I need to move an axis left, I click a button on the GUI which sends "Move Camera X Left" to the arduino and then the arduino will execute the code to actually move the position.