Did you buy an arduino after seeing all the cool instructables and now you tired of just making LEDs blink? Are you envious of all the cool walking robots people are building but don't have the experience or cash for all of those servos and expensive brackets? Here is your solution meet BoB the 4 servo mini biped robot. Bob is both easy to build and very cheap to assemble and yet is loaded with personality and endless expansion capabilities.

So how did BoB come to be?
After wanting and drooling over all the 3d printers(still don't have one) and cool stuff being built. i was offered and opportunity to design a robot and have it printed for me and so bob was born.

What are future plans for BoB?
First i would like to explain a bit about my school experience. When i was younger i dreaded school in fact the only thing that got me through the day was my tech classes. They made school enjoyable and let me into the robotics hobby i actively participate in today. Using BoB i would like to give back. The first BoB was created due to a very generous offer and since i have made many improvements. But without a printer to test each design they are just untested files. My long term Goal is to make BoB into a cheap and easy to assemble class room activity to help children get their feet wet in the world of robotics, to give those hands-on kids like me something to look forward to, and to give them an introduction to new technology that is making waves and if the future in many fields. so my next goal is to attempt to obtain a printer be it by winning it, building it over a period of time (my funds are very tight i have a child of my own) or raising the money to continue my work.

so are you ready to build?

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I have the 3d printed parts now just need final help. What screws do you use for servo brackets, and on the bottom "butt plate with servos" to the top (head)? Thank you, your help is appreciated!

k.biagini (author)  3dprinterkid3 days ago

sorry didnt see this i just used the servo screws to mount everything and the head was a friction fit or you can use extra servo mount screws


I will have an Instructable coming very soon on how to use BoB with the Botboarduino 2 and the lynxmotion controller (ps2 v3). It will (most likely) include things like how to program basic features ( walk f/b l/r and lean l/r) and more "special" features ( there will most likely be another Instructable on how to create real, working accessories for BoB). So keep checking! I will post on this Instructable when my Botboard. version will be up.

I would like to make one of these but need help. Just for clarification, where does the triple A battery compartment go in Bob and what size is the one you used?

Thank you,


k.biagini (author)  3dprinterkid10 days ago
If using a aaa pack you need almost 8 batteries a AA pack fits in the back of his head or use a rechargeable 9v battery

Thank you!

JasonRP made it!4 months ago

Thanks for making this project available.. I finally finished my version tonight!

sweaving5 months ago

Another Bob

sweaving5 months ago

I have just made one of these! will post some pics soon, i also wrote the walk avoid code myself as a learning curve! so far he can walk forwards, backwards and turn to the have modded the CAD

so an arduino nano can be fitted to the head with acces to the USB port.

i Have to say Bob is a great little Bot!

makesomeso9 months ago

nice robot. i like bob and im gonna make it !!

gadgetnerd337311 months ago
I personally made my own version with limited parts ( BoB minus the Ping sensor ) it's mostly made of cardboard and held together by duct tape, mostly because i'm 15 and don't have a 3D printer.

INSTRUCTABLE COMING SOON!!!!!!!!!!!!!!!!!!!!
JasonRP1 year ago
Anyone know where I can by the plastic parts for this robot?
k.biagini (author)  JasonRP1 year ago
you can look for a local makerspace...or any of the online print shops..BoB is on shapeways but they charge about $ can also look at the 3d printer forums there are members there that help other without printers
k.biagini (author) 1 year ago
thank you all for the support bob got first in the pocket electronics contest i am truly grateful!
Really cool!
k.biagini (author)  emilyvanleemput1 year ago
thank you :)
You're welcome!
gururise1 year ago
Do you have a working head for use with the cheaper HC-SR04 sonar sensor yet?
k.biagini (author)  gururise1 year ago
as seen here
k.biagini (author)  gururise1 year ago
i was told that with a little bit extra sanding, that it fits.
Cool! I voted for you in the 3d/Epilog Challenges! I don't know how I missed this for >10 days
k.biagini (author)  Michael_Bell1 year ago
thank you very much for the votes!
Alderin1 year ago

I've had 4 of these servos around for months, pondering how to put them to use, and I think I've just found it! Very cute design! With only 4 servos a standard Arduino can do all the positioning with analogWrite(), leaving the digital I/O pins and one analog I/O pin free for other uses! The 'head' won't fit a full-size Arduino, but since I'm going to build the legs from popsicle sticks mine will end up just being a walking Arduino.

So excited to start this build! (Yes, I'll photo-document it!)

k.biagini (author)  Alderin1 year ago
the fact that a regular arduino doesnt fit in his head was one down side. but can be remedied by mounting it to his back and running all the connections inside. i did that with my Dagu Micro M and it doesnt affect the center or gravity enough to matter. you idea has given me one and arduino biped shield! thanks for taking the time to look and thank you for the vote!
The "Moteino" would probably fit, and has built-in wireless ability (though not BlueTooth). As for a biped shield, without stacking it would be easy and cool, but not very extensible. Building it stackable would be a challenge. A biped shield plus turret shield or ping shield or IR shield would be very cool.

Stackable... My brain starts on a line of thought with built-in battery pack with separate power feed for the servos, 5dof (2d hip, 1d knee, 2d ankle) legs with a separate MCU doing the servo control to take fewer of the lines from the Arduino, maybe use SPI so that even the lines that are used aren't "used up", preserving the shield stackability. But I hear my "grand plan" alarm buzzing as I type this. :-)
k.biagini (author) 1 year ago
bluetooth stuff came in today look for the bluetooth BoB tutorial later today!
He is so adorable!!!!
k.biagini (author)  cupcake lover1 year ago
thank you
Your welcome! I couldn't find u in the epilogue contest?
k.biagini (author)  cupcake lover1 year ago
if you click vote in the upper right hand corner it will allow you to vote right from there.. thanks for the vote!
Ure welcome
Cool cool! I like the minimalist design. Definitely makes bi-peds less intimidating.
k.biagini (author)  Mizchief1001 year ago
thats what i was trying to achieve a very basic "start here" biped that can evolve into something bigger and better. and not cost an arm and a leg.
JesusGeek1 year ago
Wow, great job!!! Try adding LEDs and arms. Call him Nibob (New Improved Bob)
k.biagini (author)  JesusGeek1 year ago
the mouth holes are for 3 mm leds its just something i haven't gotten around to installing yet. and arms are being considered for the RoB upgrade
k.biagini (author)  k.biagini1 year ago
oh yeah..Thank you very much.
sdcharle1 year ago
Very nice project. I wonder could I get away with giving him a boxy laser cut body. I don't have access to a 3D printer. Yet.
k.biagini (author)  sdcharle1 year ago
yes, a member of lmr had made a laser cut version. I can make basic files. his base plate and feet should be simple...the leg brackets would have to be heated and bent. the head itself would be the parts that will take some work.
Very interesting, but what Arduino or Raspberry Pi chips are we using? I could not find a list if there is one.
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