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BoB the BiPed robot sensation

August 26, 2013

A low-cost, 3D-printed biped robot design known by BoB is becoming a bit of an internet sensation.  It was posted originally on, and then on, where it’s received almost 30 thousand views and over 250 favorites at the time of this writing.  That’s sure to increase since it recently won first or second place in two different contests (3d Printing and Pocket Sized Electronics).

Bob uses four hobby servos in the classic Loki arrangement (see Bipeds on a Budget).  There have been many other robots using essentially the same mechanics (including my own 4S-1, for that matter).  What’s new here is the use of 3D printing for essentially all the mechanical parts, making it very easy, and relatively cheap, for anyone to get started.  The parts are all on Thingiverse, so you can download, tweak, and print them yourself, or just order a set from someplace like Shapeways.

And, let’s be honest, Bob is just darned cute.

Note that this isn’t a ready-to-go kit; you have to supply (and figure out) your own microcontroller, servo controller, power supply, and so on.  But clearly it’s been inspirational enough to cause a number of BoB builds already, as you can see in the slideshow on this MAKE article.

I love minimalist bipeds, because a full-sized biped with 12 DOF or more can be very intimidating, even to somebody with some experience in wheeled robots under their belt.  A small, less expensive biped like this reduces both time and money required to get started substantially.

From my own experience, here’s what I would suggest for your own BoB:

  1. Use Herkulex servos ($36 each), which are super strong and require no servo controller; anything that speaks TTL-level serial can control them just fine.  Or, if more comfortable with hobby servos, then get a servo controller like this one ($20).
  2. A full-sized Arduino (or Raspberry Pi) won’t quite fit in the head, so use something tinier, like a RBBB (Really Bare Bones Board, $13) Arduino clone, or the Arduino Pro Mini ($10).
  3. Forget the expensive and fuzzy sonar sensor, and use a simple, accurate Sharp distance sensor ($14) instead.

Unfortunately that last mod will change Bob’s look quite a bit… the sonar sensor makes great-looking eyes!  So perhaps you could put lights (behind lenses?) where the eyes should go, and mount the Sharp distance sensor between and below them, like a nose.  They work better vertically anyway.

In fact the Sharp sensor always looked a lot like robot eyes to me, but is quite small.  With tiny Arduino boards available today, and micro servos like these ($6) or these ($12), it makes you wonder: how small and cheap could a biped walker get?

From → News, Opinion

  1. Kevin permalink

    Thanks for the blog about BoB! I did want to say a couple things, while the parts list you have is nice both my version 1 and version 3 prototypes were under $30 for all the electronics. He walks using tower pro 9g servos which are around $3 each, one uses an arduino nano and one a pro mini, both around $10 and the sonar is an sr-04 which go for under $2 on eBay, a servo controller is not necessary all my servos are controlled directly from the arduino. Just so people aren’t intimidated by the prices above. The number one goal of BoB was to be a cheap, Fun, and educational first step into robotics

  2. Hi Kevin — thanks for the comments! I’m impressed he can walk on such low-torque servos, but I guess that’s the advantage of keeping him small and light. And good point about controlling directly from the Arduino. It’s a beautiful project, and I encourage you to write up a complete parts list, or even make a kit available if you can!

    • Kevin permalink

      In currently working on a printer so I can produce a limited number of kits

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