How to Build a Robot - the BeetleBot




Introduction: How to Build a Robot - the BeetleBot

About: I am a French Canadian that loves robots and embedded electronics. I work on all kinds of cool projects, like a high-power electric push scooter controlled with an Arduino. Please visit my website for more co…

I have been in robotics since I was a kid and I am very passionate by robotics. I learn BEAM robotics around 1997-98 and started building robots for a science faire project call "Insectroides" in 2001. ( they change server and the website links does not work anymore it is on Linux and it is CASE SeNsiTIve! ) here is the old one

One of my many robots was the beetle robot, a VERY simple robot that can avoid obstacles on the floor without ANY silicon chip! ( the red ladybug, second picture, is my FIRST beetlerobot )
the red ladybug use a home made PCB carve with a dremel and two playstation motors with rubber wheel from a walkman!


It use
2 - motors
2 - SPDT switch
1 - AA battery holder

I has 16 years old when my uncle showed me the principal of the SPDT switch ( Simple Pole Double Throw). I then took this idea and incorporated the design into the (world famous) beetle robot :P

Now I am 22 and want to show you step by step instructions how YOU can make this simple robot!

here are some videos of my beetlerobot in action!

The beetlerobot in the video is made using a Printed Circuit Board ( PCB ).
This design will be use if I make a kit one day!

Check them all out here!

This Instructable is divided into three parts

- You will learn how to build the robot
- I will explain how the robot works
- I will then teach you how to fix your robot if it does not work ( Debugging )

Don't forget to read the complete tutorial before starting! And remember to wear safety glasses at all time because eye injuries ain't worth the risk! It will happen in a blick of an eye.

Have a great time!

ps- Check out Gareth Branwyn book, I made a one motor walker and he made a complete chapter with my robot!! He send me the book call " Absolute beginner's guide to building robots" A very great book!

Maybe I should write a book...

Jerome Demers aka ROBOMANIAC!

Updated july 2007 - I have added some pictures of the inside of my first beetlerobot. Home made AAA battery holder! I have also added some videos on youtube!

Updated 22 july 2007 - I added a picture and text on step 19 if your robot does not work :P

Step 1: All the Parts You Need

Here ar the parts you will need:

the robot parts'
2 - 1,5V motors
2 - SPDT switchs mechanically easy to trigger
2 - AA battery
1 - AA battery holder
1 - plastic or wooden pearl
1 - heat shrink that will fit over the motor shaft

This might cost you less then 10$ cdn.
1,98$ for both motors
1$ for the battery holder
1,98$ for both SPDT switchs
ok ok maybe 10$ is a lot!

I like to buy my stuff here

If you recycle it might be all FREE! Try searching old VCR, PS2, old toys, printer, etc
Back then, I use to recycle EVERYTHING, I got everything FREE, old VCR are very good for gears and something SPDT switchs!!! Playstation have great super good motors, the one that makes the laser move.

the tool to complet the robot
1 - safety glasses
1 - soldering iron
1 - glue gun
1 - wire strippers
1 - side cutter
1 - scissors, knife, x-acto, etc

You need some 1,5Volts motor, not 3V or no event 12V!!
Each motors are powered by a SINGLE AA battery! You will draining your battery if you use bigger motor. You can find them in toys or even at your local dollarrama, in little car, fans, etc! ( beware, they might really suck you battery down )

the SPDT swiths need to be really sensitive! I have order some the order day that where to hard to activated, that might cause some problems and the robot might not even avoid obstacles but rather hug them until death. These swiths are the most expensive part of the robot... around 1$ to 4$ each. The one I use are from Cherry.

You should check for some great motors. They even have a SPDT switch in store! I have never tried them but Grant did.

Here is a picture of the Solarbotics switchs in use. The beetlerobot was build by Grant McKee, the engineer for Solarbotics but currently works for WOWWEE in Hongkong ( poor Grant! :P)

Step 2: Preparing the Parts

Cut 13 pieces of 2,5inch long electric wire.

ps- cut 14 if you are supertisious.

Step 3: Preparing the Parts

Now just remove around 1cm to each extremity of the wire.

In other word, strip the wire at both end.

That is 0.3935 inch to be precise.

After that you need to thin the end of each wire with your soldering iron.
Oups, I forgot to tell you to plug your soldering iron, HAHA you need to wait now!


Step 4: Group Picture

Here is everything you need to start building

ok ok I forgot the paperclips and ... what else?


Step 5: Start Soldering

solder each wire to your parts.

Step 6: The Famous Third Connection

Here is the principal and most important thing about the beetlerobot.

It is call the "third connection"

In you AA battery you have 2 wires that provide 3Volts.

In reality, we only use 1,5Volts for both motors.

How can we get half the voltage? simple, you solder a wire like the picture below.
I solder a 2 inch long blue wire.

simple hey!

don't forget to browse the other pictures to see.

Step 7: Glueing Switchs

Glue your switchs on the battery holder in a V shape.

Don't forget to put the blue "third connection" wire in front.

I have found a much more efficient way to but the switchs on the battery holder.
You can glue them in a A shape so both antenna cross and will not get stuck in a leg chair.

Step 8: Glueing the Motors

Glue both motors on the battery holder

Make sure they spin forward...

I have just realise that this does not make any sense at all! :P

Look at the third picture how you can angle out the motors for speed.

Step 9: The Back Caster

Here you are going to make the third wheel, the back caster using a plastic or wooden pearl.

You can make something fancy or very simple. I took the BIG paperclip.

If you can not find a wooden pearl, you can use the paperclip directly on the floor. It will work but might catch on stuff while rolling around.

Step 10: Soldering the Brain

Here is the hard part, soldering each wire. Look at this picture and do the same :P

One thing that I forgot to do back then, was to use different colours for the wires to simplify everything.

with some special software I was able to achieve that.

Step 11: The Antenna!

You are going to give your little robot some way to feel the world.

Take the small paperclip and bend them to form some antenna.

Glue them on the metal plate pf the SPDT switchs.

I don't recommend soldering them because you need some aggressive acid-based flux or silver solder. If you don't have any experience in soldering, you will melt them.

I have already solder some using silver solder.

Step 12: Melting Some Shoes...

Take the heatshrink and shrink them on the shaft of your motors. Use a lighter to attach them.
Yo can put more layer if you want to, different colours.

I even saw some people use hot glue stick on the end of the shaft. They took 1cm of the glue stick and attach it directly to the shaft. BEWARE, you robot wil be VERY speedy and it might destroy itself on the first obstacle it will hit.

Step 13: FINISH!


You made you first Beetlerobot!

Cross your finger, put the AA into the battery holder and but the robot on the floor...

Does it work?

to stop it, you can step on it or simply remove the battery.

You can add some decoration to the robot. I took some big plastic shell find in the 2$ vending machine. I took one half and added sticker!

to debug the robot go to my website
It is in French and you will understand. You made a robot, you can read French now! :P

Oui = yes
Non = no
Est ce que les moteurs tourne? = does the motors turn?
Est ce que votre robot avance tout droit? = does it go in a straight line?

ok ok
I have added other steps to explain more about the robot and a also added a debugging section.

Jerome Demers
You can ask questions in French if you want too.

Step 14: How Does It Work?

ps- This robot does not stop the opposite motor when it touch a wall, it REVERSE the opposite motor so the robot will pivote and avoid obstacle the GOOD WAY!

BEAM powered robot will short circuit the opposite motor so the robot will need to push it's way out .

All the drawing where made with PAINT!

Step 15: How Does It Work? - the Motor

ok this is simple

The electric motor spin when you apply electricity to it. It will spin clockwise and anti-clockwise when you swap the polarity.

If the robot spin in circle after installing the battery, swap the connection of the reversing motor.

Step 16: How Does It Work? - the Motor and the Switch

Here is the complete circuit and one half of the beetle robot brain!

Click the next step to see how electricity flow in the circuit!

Step 17: How Does It Work? - the Motor and the Switch Part 2

Here you can see what happen when electricity flow through the circuit. Check the second picture.

So you can see that one battery will power BOTH motor when the robot run around your house.

The second battery is only to reverse the beetlerobot when it get stuck. SO this battery will last longer!!

Swap the battery to prolong your battery life and also the robot life.

If the opposite motor does not spin, this mean that you might have a weak battery or simply that the third connection is not working right.

Step 18: Debugging

I hope your cat is going crazy with the robot... maybe your dog?

Does your robot go in a straight line?
Here is a quick fix.

If the robot start rolling in circle you can add a "blob" of glue to the weak motor.

To know the weak motor, simply put the robot on the floor... if it goes to the left add some glue on the left motor. This will make a bigger shaft and makes the left side travel a longer distance and correct the path of the robot.

It does not mean that you motor is weak, it could just be the angle of your motor.

Step 19: Any Questions?

I hope everythings work's perfectly for you, if no, ask your questions here!

I took a picture of a special page from the wonderful book Junkbots, Bugbots, and Bots on Wheels by Dave Hrynkiw and Mark Tilden!

Mike Trzecieski wrote that back in 2001 at the Eastern Canadian Robot Games! I got my entire book signed by great roboticist! :D

I got Dave Hrynkiw, Grant McKee, Dave Simmons and his son Kyle Simmons, Scotty Dogma, Ori Barbut, Mike Trzecieski and Richard Weait the creator of the miniball... humm.. do you wonder what is a miniball? Do you want a instructable? :D LOLL

I am missing Mark Tilden signature!!!

Have a great day!

Jerome Demers
Quebec, Canada

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    6 years ago

    How would one make this wire this for four motors? Would you need to additional spdt switches or would you be able to wire two motors off the same spdt


    Reply 1 year ago

    I think it would only need two spdts


    Question 1 year ago

    Can I use white instead of blue?


    Answer 1 year ago



    Answer 1 year ago

    any color you want.


    4 years ago

    Jerome! Thanks for the project! I will use that as base for a bug-bots hockey team! ( imagine: bluetooth network of small bots with a publish-subscriber message bus - very tiny and simple but working stuff. 6 bots and a controller brain: the communitary intelligence concept applied!). I will use my box full of Arduino Uno - about 35 pieces). As I finish I will publish here!

    Tom Buckey
    Tom Buckey

    12 years ago on Step 6

    does the wire HAVE to be blue?

    Tom Buckey
    Tom Buckey

    Reply 12 years ago on Step 6

    also do you need that wire for it to work


    Reply 4 years ago

    the wire does not hv to be blue but the wire is neccesary


    11 years ago on Step 6

    what does solder mean?


    Reply 4 years ago

    its like melted conductible metal coming out form a glue gun except for it isn't glue


    Reply 11 years ago on Step 6

    Soldering is defined as "the joining of metals by a fusion of alloys which have relatively low melting points". In other words, you use a metal that has a low melting point to adhere the surfaces to be soldered together. Consider that soldering is more like gluing with molten metal, unlike welding where the base metals are actually melted and combined. Soldering is also a must have skill for all sorts of electrical and electronics work. It is also a skill that must be taught correctly and developed with practice. from


    10 years ago on Step 13

    Where does that blue wire from motor go?
    d'où vient le fil bleu aller?


    Reply 4 years ago

    To the battery holder


    9 years ago on Introduction

    can i use two 3 volt motors by only using two 1.5 volt batteries?
    does the beetle robot still work normally ?


    Reply 4 years ago

    Yes but it will go slower


    9 years ago on Step 13

    Can you please tell me the actual function of the SPDT switch and how does it work?...Please do reply..


    Reply 4 years ago

    It says how it works on step 16 and 17


    9 years ago on Step 13

    hey very nice bot ..!!wanna try right away ...but one thing which is boggling my mind is how you have fixed those motors in such a inclined angle..??


    Reply 4 years ago

    Get the the motor in the angle you want and hot-glue it on the battery holder!