:MOVE mini buggy kit + microbit - Review

Table of contents

RoadTest: :MOVE mini buggy kit + microbit

Author: davidjnorton

Creation date:

Evaluation Type: Development Boards & Tools

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: Robo:Bit - https://bit.ly/2BRQkki Ring:bit Car - https://www.ebay.co.uk/i/142921844393?chn=ps

What were the biggest problems encountered?: Assembly and calibration can be a little tricky.

Detailed Review:

Introduction

The :MOVE mini buggy kit is created by Kitronik, a company that provides a huge number of modules and add-ons for the BBC microbit.

The kit provides all the parts and components to create a two wheeled robot which can be used with remote control (thanks to the built in radio/Bluetooth on the microbit) and autonomous operation. Kitronik also sells a number of add-on board for the kit to expand functionally (covered later in the review)

The kit currently retails for £27.54 and contains:

 

1 x Set of plastic chassis parts.

2 x Micro 360 degree continuous rotation Servos (with screws and servo horns.)

1 x Servo:Lite board.

1 x full colour instruction booklet

3 x AAA Batteries.

 

It also comes with Screws/nuts for assembly

2 x Counter sunk M3 6mm screw.

5 x Counter sunk M3 8mm screw.

6 x M2 16mm Pan head steel screw.

6 x M2 Hex Full Width Nut.

 

The kit does not come with a Microbit, this needs to be brought separably.

 

Unboxing and first impressions

Contents

The contents comes well packaged with a lot of bubble wrap, so nothing is rattling about in transit. Everything is individually packaged and the Servo:Lite board comes in an anti static bag.

A lot of care and attention has been put into the presentation and simplicity of the kit, there's a cool green/white colour scheme seen throughout and a nice touch to include batteries.

Small parts

As you can see below the screws/nuts are very small and easy to lose, Id advise keeping them in the bag until you need them, they can easily fall through the gaps in the cardboard box if left loose.

Construction

The plastic construction of the chassis is well designed and fabricated, with a nice mix of matt white and glossy green finish, even the thin pieces do not feel as if they would snap easily.

Servo Board

This board can be purchased separably and is designed to interface with ZIP leds and two servos (with expansion pads for two extra components).

It connects to the Micro:bit using five screw terminals to 'mount' the board. This provides a really solid connection (when the screws are fastened tight enough) and is very low profile as the micro:bit is flush to the board, however it does make the reset button inaccessible and bit tricky to connect to the micro-usb. Some USB cables with thick housing wont fit at all.

There is an on/off switch at the top and the servo board provides power to the microbit.

The design is great to keep everything really compact however there is a slight trade off in functionality and ease of removing/adding the micro:bit due to the screw terminals.

Servos

These 'off the shelf' 360 servos are a well known brand name (fitec) and are good value and reliable.

Instruction booklet

The 31 page full colour booklet packs in all the information you'll need for assembly, testing, coding and troubleshooting. The illustrations are fantastic and the information is well laid out.

 

 

 

Documentation

Along with the instruction booklet there are a number of online resources that can be found on the product page for the kit:

 

Four lesson plans for basic movement, LEDS, drawing shapes, automaton and remote control

The lessons are really fun and well designed with links to the curriculum and a good progression. These would be great for classroom use and independent learning.

 

A number of online Guides including, Motor calibration, automatic headlights, connecting to a phone, remote control and adding an additional Servo.

 

A datasheet for the Servo board and ZIP leds.

 

A large warning about USB cables with thick 'sheaths' not being able to reach the micro-usb plug.

 

 

Assembly

Thanks to instruction booklet the assembly is very easy, suitable for absolute beginners. The process is broken up into smaller steps:

  1. Assembling the Servo board and flashing the LEDS
  2. Wheel construction and calibration
  3. Assembling the chassis
  4. Connecting the wires
  5. Testing the buggy out with block code and javascript

 

 

Each step gives you some instant gratification and breaks the whole process into manageable chunks. The diagrams are very clear and lots of attention given on explaining 'how' things are working, not just following through the steps.

On the whole I found the assembly process really fun and engaging, however there were a few things that tripped me up.

 

Small parts

The metal screws and nuts are very small, and it needs a lot of dexterity and patience to get them screwed in place, the nuts are very easy to lose so make sure to keep your work space clear. There are only 6 screws needed to hold the buggy together and its nicely designed to have everything 'slot' into each other.

 

Servo precision

I've never used continues Servos before and was interested to discover how simple they are to code (180 forward, 90 no motion, 0 reverse).

The Servos require calibrating to fine tune them to match what you'd expect to happen, this is done using a 'trimmer' on the base of the servo (a small adjustable screw).

This is an easy step, however the only way to test that both motors move at the same speed is to assemble the buggy and get it to drive in a straight line and at this point you can no longer access the trimmers without taking the whole thing apart again.

 

The other option to fix this is through code, by adjusting the speed of one of the servos:

 

However this means you can't use the Kitronik extension blocks as they don't allow for this fine tuning:

This isn't a huge deal as a lot of these blocks can be re-created using your own functions, and with enough patience you could tune the trimmer.

 

 

 

First tests

basic functions

I put together some code to test out the basic functionally and to help fine tune the movement.

This project is available here

 

I've had a lot of experience making micro:bit/Arduino buggy's using DC motors, and its a really nice surprise to see the precision and control in the continuous servo motors in comparison.

 

 

Making shapes

The buggy comes with a cut out in the centre for placing a marker pen (sharpie, thick marker may not fit) allowing you to trace the path of the buggy and draw shapes on the ground,

I put together some code to draw a circle and a square:

This project is available here

 

Circle Drawing:

 

Square Drawing:

As you can see the square didn't come out perfectly, there are a lot of factors you need to control to make sure you get accurate shapes:

1. completely flat surface

2. slow the speed of the buggy

3. use a rubber band/padding to keep the pen from bouncing around on corners

4. use a felt tip instead of a thin point pen

 

Robot art

To finish with i created code which would draw circles at random points on a canvas, this could be a really fun activity for families/young people to combine art/technology, combining different shapes and colours.

 

Drop test

In my experience, kits like this need to be very rugged, it's easy to make a mistake in the code and the buggy goes flying off the table, i did a drop test (completely intentionally, I definitely didn't accidentally knock it off the table!) to see how well the buggy stayed together.

The buggy survived falling on a wooden floor from around 1 meter drop and didn't fall apart, the Servo board seems to 'bounce out' which prevented it taking too much of the impact.

 

 

I did notice a small chip had come off one of the plastic servo board clips but considering this is the worst case scenario, the buggy is still fully usable.

Overall a really rugged construction and good materials used.

 

 

Remote control

Using a second micro:bit you can set up a remote control buggy. This was really fun to do and you can even experiment with using the gyro/accelerometer on the remote control to create a motion controlled robot.

 

 

Bluetooth to phone

Kitronik provide an phone application for android and apple, the page has a few negative comments about not being able to pair the micro:bit, this may be down to lack of documentation within the app.

All the needed documentation and steps can be found here, which could be missed if you just downloaded the app and expected it to work.

 

Download the hex file

Kitronik provides a sample code to use with the app (hex file).

it's laid out really well and is simple to understand and customise.

 

Pairing

Before the micro:bit appears in the app's list of paired devices, you need to put the micro:bit in pairing mode, there is a really good guide here.

Generally you open up your Bluetooth menu on your mobile device, then hold A + B on the micro:bit, wait a second, then hold down reset as well. which is a slight problem on the buggy as the reset button is inaccessible, i found a small screwdriver could be used to poke the reset button which saved me from disassembling the servo board.

The micro:bit appears in 'available devices' and you can pair with it, it will now appear in the app.

 

Using the app

Once the hex file has been flashed to the micro:bit, and the board has been paired with your mobile device, you can open the app, select 'connect to microbit' and the buggy will start responding to your inputs.

Its really fun and simple to do and gives you a lot of options for adding features (such as controlling the LEDS) using the additional on screen buttons.

Classroom use

We had a few free sessions at our local code club, where participants can choose to work on anything they like, i brought the disassembled kit along as i was interested to see how easy it would be for a young person to put together and calibrate.

 

Construction

On the first session the participant found it easy to assembly the buggy by following the instruction booklet, however they couldn't get the servos/LEDS to work when it came to testing them out. After a lot of troubleshooting (trying a different micro:bit/usb cable/new firmware/ swapping the servos) we discovered the screw terminals where not turned tight enough. As soon as we turned them really tight everything started working perfectly. After this hiccup the participant was able to get the buggy moving in 2 hours.  

 

Exploration

In the next session the participant used a second micro:bit to control the buggy over radio and added turning indicators, a stop light and a disco light effect when the buggy was moving, once this happened the other participants got really excited and they all wanted to try it out and a lot asked where the kit came from and how much it was.

 

Feedback

After seeing it in action i asked the group to think up projects they could try with the buggy, these were some of there ideas:

  • add a face to the screen to make an interactive 'buddy' robot (gets sad and tries to hide if it's too bright/gets pushed)
  • build a maze and have a code challenge to try to get the buggy through the maze autonomously
  • add a second micro:bit on top of the buggy to focus on object detection using an ultrasonic distance sensor which communicates to the 'wheels' over radio
  • add a paint dropper to leave a trail of paint behind as it travels

 

Conclusion

There seems to be a lot potential in this kit, and the process is definitely engaging as well as covering lots of computer science concepts. Although the price may seem expensive (nearly £30 without a micro:bit) last year we made our own DC remote controlled cars and the price of the chassis/ motor driver/ motors/ batteries probably came to around the same price and do not share the same precision in movement or professional look. If your club/school already has a set of micro:bits I would highly recommend this product as the amount of online resources and support available would allow for a lot of really fun independent learning and exploration.

 

 

Additional modules

Kitronik make 3 add-ons for buggy.

 

Bumper add-on  - £1.93

Adds a simply bumped to the front of the buggy, requires no extra motors but makes moving objects a lot easier.

 

Bulldozer add-on - £9

Adds a servo controlled 'scoop' to the front of the buggy, which can lift and drop small objects.

Adding a third servo is quite an advanced step as you need to solder in a new header and bridge a connection on the board, it will also deactivate the ZIP lEDs. This would be a good option for a more experienced user who wants to get more out of the board.

 

Tipper Trailer add-on - £13.08

Adds a trailer to the back of the buggy, it has a tipping function which can drop off small object. Similar to the Bulldozer, it need some tinkering to get a third servo working and prevents the LEDS from working. If you had multiple buggy kits i imagine in would be a lot of fun to combine the add-ons to create a mini automated building yard.

 

There is also a link on the product page to a project to create your own Halloween themed chopping weapons.

 

Conclusion

A very nice product with loads of support, documentation and potential for fun and experimentation. Due to its compact size, a few design choices can make the calibration process a little tricky, but on the whole a reasonably priced and robust kit.

 

 

Anonymous