Let's Make Robots!

"SchneeBeast" aka Rare Swiss Cow

Roams the Swiss Alps detecting & eating grass with her Theo Jansen Style Legs

   Its been almost a year since i started the original Rare Swiss Cow epic blogging event, recent interest in Theo Jansens works has encouraged me to finally present to you with the  "SchneeBeast"

   This is not an easy write up for me to do as so many spin offs came from the construction and cosmetics..... it enabled me to learn new skills and to bring some abstract ideas i had brewing into reality.

....where to start.

Etape 0 -  Embryo

 The project started after rik had been posting some gripping experiments with Theo Jansen "Strand Beasts" legs, it captivated me, respect to you rik - (-8 i pinched your legs, i hope i did not stand on your toes 8-)

Etape 1 - Proof of concept :-

I built a Lego mindstorms Theo Leg based off a sketch rik had made (i measured the proportions off my compy screen :-). The Leg worked then half hour later a second leg worked and before i knew it i had a very efficient walking biped pushing the "Mindstorms Brick" along like a supermarket trolley.

N.B. These where the closest i could get to the "Holy Numbers" using lego - more about those later.

Now i had run out of Lego linkages .... "wot to do" ...

.... wood ...replace each part with wood as i wanted an Organic feel to the project anyways....

These worked, however with a "Wobble" factor.

So out with the Dremel and a full scale rebuild of the legs.

I also noticed that i could replace some links with triangles - making it even more stable.

Full Youtube playlist Here

Etape 2 - Trivots :-

 Shops where closed for 4 days over Xmas so no screws for fixing it together..... however that turned out to be "Luck in Un-luck", my son came up with the "Daft Vader" idea ....... "Use the Polymorph , Dad"   and the idea of making "Trivots" hatched.

How to Make Trivots from PolyMorph & Video here

They worked a treat because i was able to squeeze them when warm to eliminate any "Dead-Band".

Before i welded them together i applied the graphite from a "8B" pencil where there was any wood2wood contact.

The graphite made a good slippery surface and the joints where well lubricated.

Etape 3 - Motorisation & Chassis :-

Motors where attached via a crank arm made from PolyMorph, note the embedded blind nut,

The original motors i had won off an OddBot Competition

This was the original Chassis - however the hot glue could not keep it together .....wot to do......

As i needed a more powerful motors and slower gear drive, i  upgraded not only the motors but also the "Shaky Chassis", you can also see the carbon fibre rods that fixed the alignment and you can see also the startings of the movable neck mechanism.

Training on her first Alp.

Etape 4 - Mysterious UFO :-

Then came some fun when i posted the Mysterious Object & Video Here

Which turned out to be a cows udder with radioactive fallout.

They where made by pushing a dish into a plate sized piece of polymorph to create the belly part, and then i pushed chopsticks into the warm polymorph "Sushi-Style"  to make the long wiggly bits.

Here it is in "Action" the right way up.

Etape 5 - Flattering Eyes

Her eyes have that hypnotic effect, however have a more practical and safety slant :-

When Green all is Normal                        Amber is opening of the Mouth           Red warns when the laser Distancing Probe fires

They are simple RBG Leds Pwmed to give any colour required.

Etape 6 - Cow Brains & mobile Neck

Her Brain is - An Arduino Mega with Motor Driver Shield.

Here you can also see the motor that drives the neck up an down ....using a worm drive for slowish speed.

And the Servo (Left) that opens the jaw.

Etape 7 :- A Cow is Born (my favorite part of project)

The Cows head was first contructed out of cardboard ....to get a feeling of its possibility and also to get an idea of its size.










I wanted an organic looking boney skull so i used the below model to create a PolyMorph Skinned version.

How on earth do you skin PolyMorph i hear you asking ............. Jump over here to this node & here for Video

"Tie me kangaroo down sport" .... i let you decide

And matching "Hide and Tail" to keep the snow at bay......

She is not your regular cow ......she glows........ quite brightly , what you see here is her colour (grass) sensor, her eyes match the colour she sees, no need for a makeover she is ready at all times.

Inbuilt into her jaw is an RGB led array and light dependent resistor

With this arrangement she is able to detect colours and react to them.

Here you see her tasting a robot friend - once she has detected the colour her eyes will light the same colour too.

When she detects green her jaw opens and closes as it she is able to eat grass this way (trust me it works).

Etape 8 - Theo Locomotion :-

The Movement mechanism is based off work done by Theo Jansen . Her "Strand Beast Legs" are more likely to be seen strolling the sands on the Dutch coastline....... or on exhibitions throughout the world.

I choose this style after seeing one of riks first blogs made here & general leg action here - the fluid movement entrapped me .... and so the "SchneeBeast" was born.

Here is a rough idea of the linkages and the corresponding leg movement.

Here are her "Theo Legs" legs :-

"These, then, are the holy numbers:

a = 38

b = 41.5

c = 39.3

d = 40.1

e = 55.8

f = 39.4

g = 36.7

h = 65.7

i= 49

j = 50

k = 61.9




It is thanks to these numbers that the animals walk the way they do."

Health Warning :- Do not mess with Theos holy Numbers ............. they are worth their weight in gold.

This form of movement allows the foot to lift off the ground go forwards and then touch the ground and drag backwards giving locomotion forwards - or Vicea-Verca

The more legs a "StrandBeast" has the smoother is it motion ......

.... mine had only 4 legs and when all four legs met in the middle she would lose balance and fall over.

Etape 9 - Gear Motor Encoders & S(Th)yncronisation control :-

So this is when i had the idea to install encoders into the motors and on the spline of the motor drive shaft.







This is how to Hack a standard geared motor to turn it into a rotary encoder & Video Here

With this combination on both leg pairs i was able to "synchronize the legs" to give reliable forward motion.

Etape 10 - What is the future for "SchneeBeast" :-

She was originally made to house this under her belly :-

Yes this is a Wii-Mote and yes they are lasers connected to servos.

The Wii-Mote is able to detect reflected laser light .... if you remove the IR filter off the front of it.

Then by using a Blue-Tooth link you can extract the positions of the point of light.

The lasers are set at an angle to each other, meaning that the closer the cow is to a wall the further apart the laser spots are.

More info can be found here Laser distancing using Wii-Mote & Video1 Video2

I have since worked out that you only need one laser at one angle and the Wii-mote being the second angle - all i need to do now is finish the programming.

Etape 11 Conclusion :-

Even simple robots can have a lot of meat to them, be careful as they could roam the world (stay tuned)

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Schnee-San ???

Congrats on the exhibition!

Thanks arbarnhart-sama , i was puzzled for a bit how you knew she was on her way to Japan ........(till i found rik had spilled the beans:-)

I will keep the name in mind for a forthcoming project i have lined up..............

God I love this. 


Something tells me you like cows Dan, its amazing how much you can learn from such a Megacool animal.


wow, man. amazing work. I should a robotics internship with you .

I like your polymorphing skills, Gareth...And the use of chopsticks. More chopsticks in robotics, please.

I use them a lot because when the water is boiling it helps to stop  the "cooking of the fingers".

Plus when wet the polymorph does not stick to the wood so well - i also used then to make the first part of the extruded polymorph workshop i did.

Wow Gareth.  Nice work on an awesome robot and an awesome posting.  I've just started playing around with Jansen mechanisms myself and very much appreciate the details on your build.

They are amazing contraptions...... and the best is....... the light stepping motion .... however the more the better.