bkarki
Posts: 1
Joined: Wed Oct 17, 2018 4:47 pm

Automated device

Wed Oct 17, 2018 4:55 pm

Hello

I am a Mechanical Engineering student, we are building a fully automated device for our senior design. We have to use around 7-10 motors. We talked to some people they suggested the Pi might crash if it is operating that many motors. Me and my group would appreciate any input, also what would be best way to connect that many motor to the pi.

thank you
Bivek Karki

B.Goode
Posts: 6539
Joined: Mon Sep 01, 2014 4:03 pm
Location: UK

Re: Automated device

Wed Oct 17, 2018 5:45 pm

Welcome to the Raspberry Pi forums.

If your group is working towards an assessment, why not try for yourself, document the results, and use that as part of the project write-up to justify your hardware selection?

A simple DC motor should not be connected directly to an RPi board: damage to the RPi will result. You will need a suitable motor control board, possibly based on an H-bridge chip, even for a single motor.

Typically a motor will require a minimum of two gpio connections if you expect to drive it in both rotations. Since there are 26 gpio pins presented on the 40-way header of recent models of RPi that will be sufficient to handle the maximum of 10 motors you specify.

Brandon92
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Joined: Wed Jul 25, 2018 9:29 pm
Location: Netherlands

Re: Automated device

Wed Oct 17, 2018 6:05 pm

bkarki wrote:
Wed Oct 17, 2018 4:55 pm
We talked to some people they suggested the Pi might crash if it is operating that many motors.
You can connect as much motors as you want*. And if you connect them in a correct way (and also the power) your Rpi will not crash. So, you need take a appropriate circuit to control the motors and also the cable management is imported. And it's also depends on what for type of dc motor you are using.

*there are limitation of course.

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Joel_Mckay
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Joined: Mon Nov 12, 2012 10:22 pm
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Re: Automated device

Thu Oct 18, 2018 5:11 am

bkarki wrote:
Wed Oct 17, 2018 4:55 pm
We talked to some people they suggested the Pi might crash if it is operating that many motors. Me and my group would appreciate any input, also what would be best way to connect that many motor to the pi.
We use 8-axis stepper controllers with the pi all the time for our CNC club's machines: http://www.micrometer.xyz/cdn/node/32
The open 8-axis GRBL (Arduino) source-code is inside the download: https://sourceforge.net/projects/microm ... pberry-pi/

The pi3B+ is limited to about 5-axis kinematics in the linuxCNC software due to the math involved.
However, the simple GRBL firmware accepts g-code text over a serial port, and doesn't limit how many axis you use.

For example, we also made a 20-axis hobby-servo based robot at our club, and it runs fine on the pi2 we used. Mind you the RC liPol power supply starts to get heavier with more motors, so there is probably a theoretical limit to walking platforms.

We also did another low-power 12-motor driver board for the atmega2560 Arduino that used 10 PWM outputs to drive five of the six DRV8833 modules (dual h-bridge chip). It needs 8-24vDC ~5A input, but we don't have time this year to complete the PID control firmware it needs to be useful.... I have like 5 of these collecting dust now... ;-)

Best of luck,
~J~
12-axis_mini-motor_driver.jpg
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