$10 Robot!

A super cheap educational robotics platform. Everything you need to build and program a simple robot.

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I run a robotics club in a school, for students aged 11 – 14. We generally use a Raspberry Pi for the brains in our robots, but by the time you've added on motor controllers, voltage converters, wireless controllers etc... to the price of the Pi – It all starts to get rather expensive!

You can even buy my own robot controller board – The RedBoard+, over on Tindie.

This time I wanted to make an all in one simple robotics controller, that was cheap enough to give to each of the students to keep, so once they had built their robots they could take them home to continue tinkering.

Here are the features I wanted to include on the board:

1. Dual H-Bridge – to drive 2 DC cheap TT motors, so nothing too fancy.

2. DC/DC converter – with an input voltage range of 6-12V, so you can use different types of batteries.

3. Reverse polarity protection – the students are definitely going to plug the battery in the wrong way around!

4.Enough spare input/output pins to drive a few servos or read a few sensors etc...

5. A micro controller with built in wireless communication. Preferably programmable in Micro/Circuit Python. Controllable from a mobile phone or website, so you don't need a physical controller to get started. But also with bluetooth, to connect to Playstation controllers, as we already use these for our other robots.

Nice, but not essential:

6. Through hole components – I want the students to assemble the boards themselves, so they can learn to solder, and have a better understanding of what the different parts on the board do.

7. Raspberry Pi Zero sized – so it can replace the PI Zero's in our existing robots.

8. Cheap!

This project was started back in 2022 when electronic components were still hard to get hold of. So I looked around in my parts box so see if there was anything I could use and believe it or not, I found a load of dual H-bridge modules, DC-DC converters and micro controllers.

Having a quick check on AliExpress I got an idea of the costs:

2 x Yellow TT motors = $2.00

DC/DC Converter = $0.45

Dual H-Bridge Module = $0.50

MOSFET = $0.45

ESP32 = $3.00

PCB = $0.40

Screw Terminals = $0.10

Header Pins = $0.10

6 x AA Battery holder (not including batteries) = $1.00

Total components = $8.00

These are of course subject to change but It's a good starting point.

This leaves $2.00 for materials for laser cutting or 3D printing to make a chassis – I think this is possible!

  • Chassis Design

    Neil Lambeth04/24/2023 at 21:10 0 comments

    I've started designing the chassis in FreeCAD. I would like most of the parts to be laser cut, as this will be quick and cheap on the school's laser cutter, although they could also be 3D printed. Of course some parts, like the wheels would have to be 3D printed,

    The design is not quite finished yet but I'll post the files here when they are. 

    Licence: Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)

  • Test Drive

    Neil Lambeth04/24/2023 at 20:50 0 comments

    Here's a quick video showing the board in a tracked tank chassis - we use these as the base for a lot of our robots. It's controlled from a mobile phone over Wifi using Blynk. This chassis has more powerful motors than the ones I'm planning on using, so the H-Bridge is easily up to the job.

    In future updates I'll post the code used for the moblie phone app, as well as other projects to get you up and running quickly.

  • The First PCB

    Neil Lambeth04/24/2023 at 20:05 0 comments

    Sticking to the components that I already had, I set about designing a PCB using KiCad. I then had these made by JLCPCB.

    The micro controller I use here is the ESP32 based M5 Stamp Pico from M5 Stack. I like using this micro as it smaller than most of the other boards out there, so it will fit nicely in a Pi Zero sized footprint. Secondly, it has built in wireless programming using M5 Stack's UiFlow software. This is great for programming robots as you don't have to keep plugging them into your computer to upload new code. It also has just enough IO pins to do what I want it to do.

    A slight drawback is that it doesn’t have a usb socket for programming (if you don't want to use UiFlow) – you'll need a separate usb-serial cable. Although this is not a deal breaker if it keeps the overall cost down. Unfortunately the Stamp Pico is quite pricey when it comes to ESP32 boards, It costs about $6.00, so I'll look into other options.    

    Here's a picture of the first iteration:

    I'm pleased with how this came out as it met most of my requirements. There is a MOSFET above the DC/DC converter for reverse polarity protection. It's got screw terminals for the battery and motor connectors, and header pins for 4 servos or sensors. There is a 6-pin programming header on the right hand side of the board, for plugging in a USB to serial converter. The M5 Stamp module also has a 4 pin Grove connector – for 2 additional IO pins or I2C, so it's easy to add more devices.

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