Power Requirements for Rubik's Cube Robot Solver?

Projects General Guidance
1

Hey!

So I'm currently building a Rubik's Cube robot solver that uses computer vision to detect the state of the cube via a python script and feeds that state into the kociemba algorithm which returns the required turns to solve the cube.

My question is regarding the setup of the system, my idea is that I want everything to run off the same power supply. That means the Arduino, Rasp Pi, 6 stepper motors, LCD screen, and an Adafruit RGBW Neopixel LED Strip (2M, 30 LEDs/M) to use for aiding the webcams in the color detection of the cube.

Right now I have a raspberry pi 3B+ doing the color detection (via two Logitech C920 webcams) and the cube state solving. The pi then interfaces with an Arduino Uno (clone) to control the 6 stepper motors attached to the cube.

The 6 NEMA 17 stepper motors (per phase: 2.6V, 1.7A) I'm using are from banggood. The datasheet is here.

The motor drivers are DRV8825 clones from here. All drivers are set to a vref of 0.75V and wired for full step mode as depicted in the attached image taken from Pololu's page on the DRV8825. All drivers have a 100uF 50V capacitor connected to the VMOT and GND. All drivers also have heatsinks on them and are wired up in parallel.

I'm also going to be using an 80mm Noctua PWM fan to cool all the components. This is because I'm going to have all my components (including the PSU) in a small 3D printed PLA enclosure so I need an active fan to cool it all.

Would this be plausible? From my calculations, if I use a 24V power supply, the power requirements are as follows (please let me know if my calculations are off):

  • 6 Stepper Motors: (2.6V * (1.7A * 2)) * 6 = 53.04W
  • 2M, 30 LEDs/M, RGBW, Adafruit Neopixel Strip: (5V * 2.4A) * 2 = 24W
  • Raspberry APi 3B+ (w/ 2 C920 webcams + LCD display): 5V * 3A = 15W
  • Arduino Uno: 9V * 0.5A(??) = 4.5W
  • Noctua NF-A8 PWM Fan 12V * 0.08A = 0.96W

Total: 97.5W

Neopixel power consumption was taken from here.

I would also use a switching voltage regulator to bring the 24V down to whatever the component needs.

I was looking at power supplies, would something like this MeanWell 24V 4.5A power supply be enough? If not, what about this?

Along with that, would it be better if I got a regulated supply or an unregulated supply? Finally, when it comes to powering the raspberry pi, would it be better to power it through GPIO or MicroUSB? Is there a reason to give up the power protections implemented for the MicroUSB power?

Thanks!

0J4232.600.png

2

You need a strong 5V supply that also can be used for the Uno. For the fan and the steppers another 12V supply can be used. You may want to use a 12V primary supply and one or more 5V step-down regulators.

3

Hey, thanks for the response.

So something like this would be ideal then? Although with it being 102W I'm a bit worried that I may not have enough leeway in case more power is drawn or if I want to add another stepper motor for example. The reason I chose a 24V power supply is that I've read in numerous places that 24V is recommended for stepper motors to achieve max torque and speed (and also because there were a lot more options when it came to small 24V power supplies, which is required as the enclosure doesn't have much length). I'm trying to push the speed of the motors so maybe I could go for a 24V supply with some 5V and a 12V regulator or instead go for a 12V supply with a 24V boost converter?

4

I have no idea, leave it to you.

5

Understood, thanks for the help!