Advise on many stepper motor project

Hey everyone,

I am starting on a big project for which I want to build a prototype first. As I see here on the forums people prefer to get some information about the project to better judge a question, so that is what I will do first. But feel free to scroll directly down to the questions!

The prototype will consist of an ordering system, which will be controlled through a touchscreen hooked up to a raspberry pi. Once the order has been placed/paid it will be send from the raspberry pi to a set of arduinos which will control around 20 stepper motors that will prepare the order (the number of motors will increase in the real product if we decide to start producing it). The stepper motors will rotate the belt, cut the bread and other ingredients, place them at exactly the right moment etc. The end result would be a fully prepared meal.

Since I want to hookup an screen, I think it is best to use a raspberry pi for that since it has an integrated hdmi output. For the part of connecting the raspberry pi to arduinos is done to make sure our workload on the raspberry pi will not become to heavy. I was wondering if this is the best method to connect multiple arduinos to a pi or that there are faster/cheaper ways? (Link: https://www.instructables.com/id/Combine-1-or-more-Arduinos-with-a-RaspberryPi/ ). I believe the normal way for connecting enslaving arduinos to a raspberry pi would be using serial communication but if read this correct on the internet this doesn’t work for multiple arduinos.

In addition, the motors will only make 180 degree turns in one direction so are stepper motors best suited for this kind of motion? To be even more precise I would like to make the 180 degree rotation in around 0.1 second and then wait 0.4 seconds and repeat this over and over.

As you might tell I am not that experienced with electrical engineering so I just don’t know what is the best solution. That brings me to the next question how many motors can I run roughly on one arduino with the motion described above. I could hook up many arduinos which each will control few motors or have fewer arduinos with port expanders (MCP23017) and stepper drivers (drv 8825) to reduce the number of GPIO pins required per stepper and allowing to use more motors per arduino?

This Forum is intended to support Arduino controller based projects. Rasberry... Yes,somebody might know things. Another intention of this Forum is to support beginners to help them get started. As all helpers do this for free the support is not intended for commercial interests, the industri etc. An exception is to use the "Gigs and collaboration" section. There You can make business agreement with future collaborators, paying for their work.

You can connect several Arduinos to the Pi, each on its own USB/Serial interface. Mega can control 17 Stepper motors with appropriate controller for each one, assuming 4 pins per controller.

karelslowi: The stepper motors will rotate the belt, cut the bread and other ingredients, place them at exactly the right moment etc. The end result would be a fully prepared meal.

Have you any experience of building a machine that can cut bread, etc?

If not I suspect you will find that the mechanical part of it is not at all simple, especially while maintaining required food hygiene standards.

Which part of the process do you think will be the most difficult from a mechanical point of view? I suggest you start with the simplest possible control system (maybe just an Uno and the Arduino Serial Monitor for control input) and see if you can get it to work. Then do the same with the the next most difficult item.

...R

Railroader: This Forum is intended to support Arduino controller based projects. Rasberry... Yes,somebody might know things. Another intention of this Forum is to support beginners to help them get started. As all helpers do this for free the support is not intended for commercial interests, the industri etc. An exception is to use the "Gigs and collaboration" section. There You can make business agreement with future collaborators, paying for their work.

Although I have to admit it sounds like a commercial project it is not. I am just an ultra nerd who likes to automate everything in his house even preparing lunch. Thank you I will ask the raspberry pi stuff on their forum.

CrossRoads: You can connect several Arduinos to the Pi, each on its own USB/Serial interface. Mega can control 17 Stepper motors with appropriate controller for each one, assuming 4 pins per controller.

Never knew that was possible, thanks! I will look into the mega, I could probably use less pins per controller right? Since I only need rotation in one direction

Robin2: Have you any experience of building a machine that can cut bread, etc?

If not I suspect you will find that the mechanical part of it is not at all simple, especially while maintaining required food hygiene standards.

Which part of the process do you think will be the most difficult from a mechanical point of view? I suggest you start with the simplest possible control system (maybe just an Uno and the Arduino Serial Monitor for control input) and see if you can get it to work. Then do the same with the the next most difficult item.

...R

Yes I have experience with making such machines, just without the motor so that should be doable still it is a challenge tho. But who doesn’t like a challenge.

I think the hardest part is the communication from raspberry pi to arduino and efficiently setting up the electrics (so connecting the motors to drivers to the arduinos) since I have less expierence in that part.

Yes good suggestion I will start with that! By the way, what do you think of using stepper motors for the motion I described?

karelslowi:
Yes I have experience with making such machines,

[…]

By the way, what do you think of using stepper motors for the motion I described?

Please post a diagram that illustrates how one of the machines works so we can visualise what you are hoping to create. It will make it a lot easier to answer your question.

…R
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