SiRo 2.0 - a Cheap 3d Printed Robot for Microbit

While redesigning the SiRo into the SiRoAT, I had to make some changes to the frame, so that it could mount the forward looking ESP32 Cam. I realised that I could take those changes and use the mounting system, so that you could mount different sensors and moduls on the SiRo. Thus SiRo 2.0 was born.

SiRo 2.0 is slower to print than the SiRo, but you don't need a coaster wheel and it is able to mount different sensors and moduls on the front. I have made some moduls myself, that is included here, but it is relative easy to design them yourself.

Materials:

Micro:bit

Motorbit

4 x M3 30mm screws

2 x M3 6mm screws

4 x M3 Spacers

8 x M3 nuts

2 x TT130 motor

2 x Wheels for the TT130 motor

L298N Dual H Bridge motor controller

1 x 9 volt battery + battery holder

A bit of wire. In two different colours if possible

A small piece of double sided tape

Filament for the 3D-printer

Tools:

3d-printer

Soldering Iron

Screwdriver

Wirecutter

First step is to slice the stl file in your favorit slicer and print out the chassis.

While waiting on the 3d printer you can start by soldering wires on to the motors. Take 4 pieces of wire, each should be 12 cm, strip them and solder them on to the motors. If you can, then I would advice you to use two different colours of wires. It just makes it easier to keep track of them.

We now take the 2x6 mm screws, 4xspacers(I use 8 mm), 4 nuts and the motorbit. First install the 4 spacers on to the motorbit, with the 4 nuts.

Then install it on the chassis using the 2 screws.

For next step we need 4 x 30 mm screws, 4 nuts and the motors.

Install the motors as shown on the picture.

Then

First screw the two motors on to the motorbit using the connector terminal as seen on the picture.

Then screw the battery holder onto the motorbit. Black wire to GND and red wire to VIN. Then take your small piece of double sided tape and place it at the rear of the smar car and put the battery on top of it.

Then push the wheels on to the motors and put the micro:bit into the motorbit.

Now the chassis is is finished and you have your robot.

Now the cool part about SiRo 2.0 is that it does not have a caster wheel and without the screws to keep the caster wheel on, there is plenty of space at the front to install different moduls there.

The most simply, but also very effective thing is to just put a breadboard at the front, but I have designed a number of moduls that allows you to install upright breadboards, sonic sensors or a combination.

All of them can be installed by pressing them into the three holes at the front.

Now I had a cheap robot claw laying around the house, so I also designed a holder for that. Printed it out and mounted the claw in it with 3 x 3M 20 mm screws and 3 nuts. Then I mounted the holder on the robot.

Since the claw should installed pretty tight into the holder and I couldn't know the thickness of the plastic other peoples claws might be, I also made 2 small layers of 3D printed plastic that can be put in with it. One is 1 mm thick and the other 0,5 mm.

Since the holders opening is 5 mm, then if you have a claw made of 4 mm plastic, then you can put the 1 mm layer in with your claw and it should set thight with the holder.

Since I wanted to control my robot with another microbit I wrote a simple program. (I am sorry that it is in danish)

First I went to makecode.org and programmed the sending microbit.

I assigned it a radiogroup and programmed it to send different numbers based on the angle I held the microbot and if I pushed the a or b button.

Then I programmed the resiving microbot that is on the robot.

First I went down to extensions and found the motorbit extension. Then I assigned it to the same radiogroup as the sender and made it do different actions depending on the number that was send to it.

You can find the two programs linked bellow.

Sender

Resiver

I then downloaded the two programs to my two microbit and the claw robot was finished.

Now it is rather easy to design your own moduls.

To see an example you can access my ClawHolder thinkercad file here and a design with just the three studs you need to connect to the chassis can be found here.