Jansen Walker - Beta 2

An openly designed Creative Commons licensed robot.*

What you see here is Beta 1 of the Jansen walker, a laser-cut robot, based on the Jansen Mechanism. It has 8 legs and scuttles similar to a crab walking sideways. The brain is a Arduino, and the legs are powered by 2 micro-servos modified for continuous rotation.

The Beta 2 plans contain several improvements (not pictured), including 3 pairs of leg on each side instead of 2, a drop-in platform for the center, also several other small improvements, and improved building plans.

If you would like to buy a kit of just the plastic see the Donate / Buy page. Note this is plastic only, no hardware.

Walker 1 Walker Legs Walker Front



Jansen's Transport Jansen Mechanism
Theo Jansen

This project is heavily influenced by Theo Jansen's natural gearing mechanism, it’s a very efficient mechanical leg design for converting rotary motion into leg movements, and is very elegant in my opinion. The basis is the relative distance of the 12 joins, Jansen calls them "The 12 Holy Numbers". The numbers were developed with a genetic algorithm. In a couple of interviews that he wrote the evolver on a Atari STe computer and it took literally months of 1990’s processing power to find the solution.

For more info on Theo Jansen as well as some video and pictures see strandbeest.com.

I started my design in early 2009, and it has evolved quite a bit from my early designs. If you are interested in the progression search for Jansen on the blog.

I've spent quite a bit of time on the mechanical design on this robot, and since all the parts are laser cut, absolutely everything must be modeled, excluding the obvious bolts, and electrical parts.


All plastic parts are cut from 2mm acrylic, and for the most part pretty straight forward, no special preparation or modification is necessary after they are cut. Although, the feet can be dipped in rubber for better grip on smooth surfaces.

Parts 1LegsRubber Dip


The teeth on the inside of the servo gear have 15 teeth around a 4mm hole, Both gears are 2 layers, one grips for rotation, the other stops movement along it's axis.

GearGlued GearSingle Leg


The servos are modified for continuous rotation, and it's easier to do then it sounds like. The first one took about a half hour, the second about 15 minutes. Quick step by step instructions.

ServoServo 2


The assembly is fairly straight forward, but there are many steps. In general all the parts layer on top of each other using the long threaded rods as the main support structure. You'll need to use the images for the main part of the body, and refer to the "Leg Assembly" PDF for an exploded view of the layers of an individual leg.

Electrical Circuit

The circuit is very simple, it's primarily why I chose to use servos instead of geared motors.

  • The positive leads on the servos go to the Arduino's regulated +5v, and the negative goes to the ground pin
  • The servo's control wires go to the digital pin 2 and 3

The Arduino then sends a PWM signal to the servos to control the speed, which is pretty simple to do in the Arduino's software. The alternative would be to use a separate motor controller which adds some extra cost to the project.

Parts and Tools

Parts List
4 0.5in m3 (#6 US) bolts (Center platform)
12 0.75in m3 (#6 US) bolts (1 Per leg)
36 0.75in m2 (#8 US) bolts (3 per leg)
12 1.5in m3 (#6 US) bolts (4 for battery, 4 per axle)
2 12in m3 (#6 US) threaded rods
  (66 bolts total)
3 m3 stand off nuts (arduino standoff)
94 m3 nuts (#6-US 7 per leg, 19 per axle, 12 for center)
84 m2 nuts (#8-US 9 per leg)
36 m3 locking washers (#6-US 2 per leg, 6 per axle)
24 m2 locking washers (#8-US 3 per leg)
  (238 washers and nuts total)
108 Plastic leg parts (9 per leg)
30 Plastic axle/gear parts
7 Plastic parts for center platform
1 Can of plasti-dip, enough for many walkers. (Optional)
  (146 plastic parts total)
  (450 hardware parts total)
1 Arduino or Arduino clone
1 Power source (6-20 volts)
2 Micro servos, modified for continuous rotation
1 Breadboard for easy electrical connections (Optional)
10 Short wires for bread-boarding
4 Buttons for directional control (Optional)
  (21 electrical parts)

Tools Required

  1. Assorted small wrenches
  2. Needle-nose pliers
  3. Super glue
  4. Drill (optional)
  5. 2-3 hours assembly time


Beta 2

Beta 1

Download and enjoy, subscribe to the blog for updates.

Other Notes

I've marked this as non-commercial creative commons licensed, but it would be very easy for anyone get me to license a commercial version to almost anyone. For the most part I would just like to make sure I agree with the usage, and make sure I am aware of it.

Creative Commons License
Jansen Walker by 4volt.com is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.