Introduction: Easy Robotics With Cardboard and BBC Micro:Bit

By LOFI Robot
About: LOFI Robot is an educational robot construction kit designed to help young makers and inventors learn basics of coding, electronics and mechanics. LOFI Robot is fully OPEN SOURCE and based on the most popular…




Who are cardboard robots for?

CARDBOARD ROBOTS is a set of free robot plans and building techniques easy to replicate worldwide with recycled materials and basic electronic components. Designed to be made at school with students aged from 10 years old and up.

Our goal is to make cardboard designs as useful as possible for teachers and educators worldwide. We keep our designs basic so students can build them within limited time frame at school. We propose to use only easily accessible, free (cardboard) when possible, or reasonably cheap (Micro:Bit) materials and components that are available worldwide.

Sustainability is a welcomed side-effect of this approach.

Our robot designs contain mostly recycled and recyclable materials and connecting elements are reusable (nuts and bolts and rubber bands).

Step 1: How to Start

How to start

  1. Choose the robot and download design file
  2. Print the design file — remember do not scale it! set printer to print without bleed margin
  3. Glue the design card to cardboard, wait for the glue to dry and cut out the parts — remember black lines are to be cut, dashed red lines are to be bent
  4. Assemble the robot with nuts, bolts and rubber bands with a help of the screwdriver
  5. Attach motors and Micro:Bit to the construction
  6. Code the robot in MakeCode — you can find example code in our manuals

Step 2: Building Manual


Cardboard

As you have probably noticed by now cardboard is a thing we pay attention to here So we think that cardboard is good enough for robotics — REALLY! It is strong enough, it is easy to make models with, it has its limitations but in an educational environment it is not a bug — IT IS A FEATURE.

Robotics is about solving problems and working around your hardware limitations. Look around you — you will surely find great supplies of free cardboard to reuse so do not by another plastic toy — get creative with what you have on hand Below you can find some tips and tricks how to work with cardboard in school with your students. These are not strict rules but field tested good practices, if something else works with better with you and your students LET US KNOW!

Tools you will need:

1. Screwdriver
Main assembly tool for cardboard robots used for nuts and bolts and making punctures in the cardboard. We recommend using 10cm long screwdriver with PH0 phillips tip best for M3 nuts and bolts. It is also more comfortable to use a screwdriver if its handle has rotatry tip.

2. Scissors

Use good quality scissors for with fairly sharp tip to cut the cardboard and making bending traces.

3. Nuts and bolts

In our design process we found out that M3 nuts and bolts we were using in our previous LOFI Robot wooden construction system are a great way for cardboard constructions as well.

Main advantages of nuts and bolts:

  1. Provide sturdy and firm jointIt is easy to make corrections and take a step back in your assembly process — reduces building stress
  2. Reasonably cheap when bought in quantity
  3. Reusable and almost indestructible — unless your students will eat them, you can reuse nuts and bolts millions of times
  4. Clean connection — does not make mess as glue and adhesive tape

PROTIP!

Use screwdriver to puncture the cardboard and make holes for bolts. It requires some practice but with proper guiding this assembly technique is accessible and safe even for small children.

4. Rubber bands

Standard rubber bands are a great thing for putting things together and greatly speed up prototyping with paper. Rubber bands are easy and fun to use even for small kids, encourage play and boost creativity. Furthermore parts assembled with rubber bands can be reasambeled as many time as you want which takes down fear of failure and encourage experimentation.

Advantages of rubber bands:

  1. Easy to source from recycled packaging
  2. Cheap to buy in bigger packages
  3. ReusableClean work
  4. Fun and inspiring to use

Do not use glue or adhesive tape!

Usually wherever you find building instructions for paper models, you are guided to assemble them with paper glue, glue gun or any type of adhesive tape.

We encourage you not to use them because they are:

  1. Messy — your hand get dirty, paper gets dirty, everything get dirty with glue
  2. Glued connection is irreversible — you can not take a step back and review your idea — this rises design and assembly stress
  3. Needs refill — paper glue and adhesive tape is not so expensive still it is a cost to refill your supplies from time to time
  4. Glue takes time to dry and stiffen — lesson time is to precious to waste

Step 3: Cardboard Types

Best type of cardboard is a one layer 3mm cardboard you can find it in small and medium boxes usually food packaging, shoe boxes etc. It is easy to cut with scissors and bends nicely.

Thicker cardboard as two layer 6mm you can see in the picture above is to tough for kids to cut with scissors and is hard to bend. It can be found in fruit and vegetable crates in grocery stores. It is hard to make models out of it but can be useful for elements that require stiffness as wheels.

Cutting cardboard

We suggest cutting cardboard with good quality scissors as it is a method safe for kids. You would surely get a cleaner edge with a proper utility knife but for safety reasons you had better not give them away to your students, unless you know what you are doing

Making connections
As a main method of making connections within cardboard elements we suggest using screwdriver for making punctures and then twisting it with nut and bolt. This method provides strong and rigid connection, is very easy to make even for small kids with some practice, you can disassemble the connection and fix it easily. Also nuts and bolts are endlessly reusable.

PRO TIP — for some quick prototyping and testing you do not even have to screw the nut on the bolt. The bolt thread will keep the cardboard connected for a while.


Cutting holes

Puncture the cardboard in four corners of the rectangle hole you want to make, this will give you a tracing points for scissors cuts on both sides of the cardboard sheet.

Step 4: Electronics Manual


Minimal set of electronic components

To get started with cardboard robots you need a really small set of electronic parts:

  1. BBC Micro:Bit
  2. Servo connector (female) to three alligator clips adapter cable
  3. 2 x AAA battery pack — with AAA alkaline batteries
  4. One servo motor — depending on the project 180deg or 360deg (so in fact you should have two of them, but only one can be connected at a time)

With this setup you can get a really cheap robotic kit (cost altogether around 25USD) that will allow you to make all of our one-motor projects.


With a help of the adapter cable you can connect the servo motor directly to the Micro:Bit, even tough the board can provide very little power directly from the 3,3V pin (about 90mA) it is barely enough to power one micro servo.

PROTIP — Micro servos with plastic gears (usually in blue housing) require less energy than the one with metal gears (usually in black housing like Tower Pro MG90S) — so if you plan to power it directly from the Micro:Bit board choose the plastic blue ones

PROTIP#2 — If you power the board with AAA batteries you have to use ALKALINE BATTERIES they provide 1,5V each so two of them give you 3V which is already below required 3,3V but will get the board and one micro servo running for quite a while. Regular AAA Ni-Mh rechargable batteries like Eneloops etc. provide only 1,3V each so two of them give only 2,6V which is not enough to drive the servo.

Suggested electronic parts

  1. BBC Micro:Bit
  2. Micro servo motors — two types -180 degree and 360 degree (full rotation)
  3. Micro:Bit adapter to connect servo motors
  4. Magnetic micro USB cable

1. BBC Micro:Bit

We love Micro:Bit since its introduction in 2016 and now as it grown mature with software, users community and educational content it is a no-brainer to make it a heart of an educational-centered STEAM project. Micro:Bit is much more capable than Arduino and much simpler to use than Raspberry Pi. Packed with built in sensors and wireless connection capability this board is great for a basic robot controller. Micro:Bit has plenty of onboard sensors:

  1. buttons
  2. accelerometer
  3. magnetometer — compass and magnet sensor
  4. light sensor
  5. thermometer
  6. capacitive touch sensor
  7. analog pins

For basic robotics projects you can easily go on with the builtin sensors so you need no extra accessories for the board.

2. Servo motors

The only external components you need to build a simple robot with a Micro:Bit board are motors. We suggest using only micro servo motors as they can operate on 3.3 volt signal provided by the Micro:Bit and you can get them in two modes:

  1. 180 degree — for pivots, gripers, arms etc.
  2. 360 degree — full rotation — for wheels

3. Micro:Bit adapter

The only limitation of Micro:Bit is that you need some kind of adapter to connect motors and provide power supply. For the sake of simplicity we suggest using adapters listed below:

  1. Elecfreaks ring:bit V2 (suggested)
  2. Kitronik SERVO LITE board

If you have basic electronic experience you can workaround and connect servo motors to Micro:Bit without the adapter, or make this kind of board on your own.

Other adapters

There is of course a huge choice of more capable Micro:Bit adapters with much more features. For the sake of simplicity we suggest only basic solutions with micro servo and we find smaller adapters with less features more suitable for basic school needs. To go on with any other adapters or Micro:Bit extensions you will have to make some modifications in our robot designs,

4. Magnetic micro USB cable

This accessory is not necessary but it is ESSENTIAL to lenghten your Micro:Bit board lifetime in school environment when it is tossed around from one kid hands to another. Micro:Bit is rather solid board with now specific parts to bend/break/tear apart but it weakest point is definitely a MICRO USB PORT. Makecode software uploads the code only via usb cable and as you build a moving robot you will likely want to plug and unplug it many times uploading new iterations of your code and testing it. When this process is in hands of your inattentive teenage students damage of the usb port is only a matter of time.

Magnetic cable solves this problem, you only plug the connector to the usb socket once and then use the magnetic plug to connect the board to the computer. If your robot falls to the ground or moves unexpectedly, magnetic plug detaches and keeps the usb port safe.

For more robot plans, building tips and lesson plans go to: https://cardboard.lofirobot.com/

Step 5: Designs

For more robot plans, building tips and lesson plans go to: https://cardboard.lofirobot.com/