Test Roboter ein arm bein

Impressions of the construction: Remote-controlled robot on his bicycle

Hugo has had several shows since we finished him. This small remote-controlled robot entertains the young and mature as well. If you are interested in technics,  you want to know how Hugo was built. That’s why you should get look behind the scenes. I had to learn many things, because to create an animatronic puppet, calls skills in various fields who had never touched me before. Some subjects were ( are ) so new and complex that I got myself the help of friends and especially my dear brother Florian. Thank to all who helped. Here is an interview from the Fab Lab Berlin where I’ll tell you about the development of Hugo:

The idea

The idea of ​​a character who drives a tricycle is not new. At the latest with the movie “Saw” many knows the little scary puppet driving on a tricycle.

Since I play robot walkabouts, the character on the tricycle should necessarily be a remote-controlled robot. Many robots from movies are not suited for walk aroud entertainment because they are too martial or have a menacing component. I definitely wanted to develop a character who is sympathetic at first glance. Family suitable so to speak.

That’s why I treated  Hugo with big “Disney Eyes”. Hugo should have a story. He comes from the past, therefore he acts and looks retro. Eyes and mouth should be pixelated or at least not be perfect, as you would get it today with screen displays.

At the upper body you find a floppy disk drive and other applications that remembers to servicebots and toy robots from the mid 80s like the Omnibot.

But enough of the preface. Here comes the impressions of the construction:

The bike

The bicycle is the first major component. First I wanted to be able to remote control it and then “just put the doll in top of it”.

We built a dummy so that we could test the proportions.

Dummy zum Test der Proportionen

Dummy to test the proportions

The drive

It is powered by a wiper motor. He has enough power and can move the weight of about 50 kg if the ground is even. The power needed to be transferred to the rear axle. We tried 3 different systems that did not work. Finally, we have mounted a second gear  directly to the engine via a chain.

The control

Steering left and right sounds simple but is technically difficult to implement, if you have to move more weight. First, we tried  strong servo-motors, which can push up to 30 kg. Although the are super fast and accurate but the wrong choice for such a project and very vulnerable .

The second approach was an engine out of a car, which adjusts the seat height. This has the power, however, is quite slow .

Ultimately, we chose a linear actuator which normally electronically open and closes heavy doors.

The bike design

The tricycle that I bought for the project should serve as a backbone. The technique is stowed in a box behind the seat.  For the casing of the wheels, I decided to go for the “retro approach”.

The actuator has been installed in the center bar. We have taken the original rod and replaced by a steel profile. Florian has built a beautiful cover.

For the wings, he has created a positive and molded a negative. Than he laminated fiberglass and epoxy to beautiful wheel arches. A lengthy work with several attempts .

Mittelstrebe fahrrad stahl profil

Steel profile for the center bar

Mittelstrebe fahrrad stahl profil mit abdeckung

Cover for the linear actuator

flexen Mittelstrebe fahrrad stahl profil

Preparation of the center bar

flexen Mittelstrebe fahrrad stahl profil von vorn

finishing touches

Test kotflüger Schutzblech breit

The first draft of the fender was discarded because it acts too massive

Erster Anlauf für die Radkästen

first attempt for the wings

Postitiv rad abdeckung. kotflügel spachtelmasse

Creating a positive of the wheel cover

Postitiv rad abdeckung. kotflügel spachtel

Sanding, sanding…

Postitiv rad abdeckung. kotflügel 2

… and sanding (Thank you Florian)

Kiste für abformen Mold negativ form abformen

Box for the mold

Mold negativ form abformen

Molding of the wings

Mit Glasfaser und Harz wird laminiert

Laminated with fiberglass and resin

Kotflügel epoxidharz glasfaser grundform

Assembling the two halfes

Kotflügel epoxidharz glasfaser trocknen

With assembly aids

Kotflügel epoxidharz glasfaser radkasten

Test on tricycle

Kotflügel epoxidharz glasfaser radkasten front

The shape fits

Die Teile werden grundiert

The parts are primed

rotes schutzblech kotflüger Ral 3000

Final after painting

Abdeckung metall Ral 3000

Painted cover

Dreirad rot lackiert ohne kiste

Painted parts are mounted

Kiste Abdeckung Stahlgerüst

Box for battery and technics

Kiste Abdeckung MDF

Cover made of wood

Kiste Abdeckung MDF hinten

Rear view

The Robot

Robot design 

As mentioned at the beginning, Hugo should act cute and appealing. That’s why he has big eyes and small body in relation to the large head.

The wooden parts, I wanted to cut with a laser cutter. Here in the Fab Lab Berlin there was so far “only” a laser cutter, with which one can cut boards of 600 x 300 mm. All parts had to move in this framework .

The curves I have realized by “slotting” the wood .

Arms and legs I had constructed as “little boxes”. Unfortunately, that was not stable enough. At the third approach, the legs were  built solidly. Multiple layers MDF panels were bonded .

The robot mechanics

Hugo can move the head ” right / left ” and ” up / down ” .

Move head right / left

The head rests on a ball bearing of a large mobile role, as they are known by a shopping cart and can be bought at the hardware store. The servo is mounted underneath.

Moving head up / down

The servo motor must deliver only minimal forces, thus I first cutted his head and put him together. By testing i looked for the centre of gravity. Its very high and more in the front of the head. In the consequence, the neck seen from the side is quite thin, because the “chin” and “back of the head” have plenty of space .

Animated LED eyes

The eyes are made of a 8×8 LED matrix which are controlled by a microcontroller. Altogether there are 128 LEDs for both eyes . Hugo has ten animations that plays after a certain weighting in random. This gives the eyes the illusion that they are “real”. The animation is more static if it is priori defined and runs as a “movie”. At the beginning I included also negative emotions, which I have removed. Positive and neutral emotions of the eyes match best with a friendly and open puppetry .

Animated LED mouth

Just like the eyes also the mouth is made of LEDs. For that I have used three 8×8 LED matrixes.

Here I use a technique, that is also used in animated films for years. When characters are animated while talking, 6 animations are enough to give the illusion. It is called the AF system.

The system was developed for cartoons in the 1960gern .

In cartoons the mouth animations are placed on the language. That would be too complicated for Hugo. The animated images are displayed on the sound volume. So you reach a good enough illusion that the mouth movements are in sync.

Mundanimation wie für Zeichentrickfilme nach dem A-F System

Mundanimation wie für Zeichentrickfilme nach dem A-F System

Operate the remote-controlled robot

Hugo is reduced to the most important skills that have to be operated manually: Moving forward and backward, steer right / left. Head to the right / left , or head up / down. The rest, eyes and mouth, is automated. This has the advantage that you can play it more easily than others animatronic puppets. It takes only 4 control levers.

Use of the Puppet

Hugo play at events, festivals and fairs. The next challenge is to bring this fellow to life. I dedicate myself now to playing him well so Hugo comes across authentic. The way you play a puppet makes a huge difference of its effect. That is why I am working on his repertoire as “useless knowledge” and songs that he sings as well as his backstory. So it remains an interesting interlocutor for young and grown up alike.

Roboter kopf erster entwurf holz mdf lasercut mit outline

First draft with Outlines

Roboter kopf und gelenk erster entwurf holz mdf lasercut

First draft: robot head and joint

Roboter kopf erster entwurf

Problem of covering a rounding with wood

roboterkopf erster entwurf mit biegung

Test the rounding with paper

Lasercutter holz schlitzen

Laser cutter cuts MDF board

Lasercutter MDF Teile ausgeschnitten

Finished parts lasercutted

Lasercutter Teile herausnehmen

Items are removed from the board

MDF 4 mm geschlitzt für biegung holz schlitz muster

MDF board testing with slots

MDF 4 mm geschlitzt biegung holz schlitz muster

Close up slits for rounding

biegen MDF 4 mm geschlitzt biegung holz schlitz muster

wooden slotted board bent – with good result

Roboter dummy puppe für dreirad aus holz

Wooden dummy 2 to test the proportions

Test Korpus roboter

Test of proportions for the body

Roboter front Bauch mit floppy diskettenlaufwerk, led display und herz

Body with applications such as floppy disk drive, switches, LEDs and LED display

Arduino steuert Bauchdisplay

LED display is controlled by a microcontroller ( Arduino )

Test Roboter bein

Prototype first leg …

Test beinlänge Fahrrad

… didn’t passed the the stress test.

Roboter Bein und Arm MDF Holz verschraubt

New bolted arms and legs

Test Roboter ein arm bein

Mounted new arms and legs

Hugo sitz unlackiert

Fully assembled and color test on the foot

Roboter Einzelteile aufgreiht beine kopf arme Körper

The parts are waiting for treatment with sandpaper

Schleifen Holz bein roboter

Make everything nice and smooth

werkstatt schmirgeln

Sanding small parts

gehacktes Babyphone als Mirkofon

Hacked baby monitor and used as wireless audio connection ( Twice wrecked because of reverse polarity )

gehacktes Babyphone als Mirkofon mit kopfhörer anschluss

Hacked baby monitor with extended microphone and headphone jack

Roboter gerngesteuert MDF gehäuse

Robot remote controllers. cases made of wood

Roboter teile zum lackieren aufgehängt

Ready for painting

Roboter kopf in der lackiererei abgeklebt

Layer one is finished

Lackierter Roboterkopf petrol

Robot head with the final outlines

Roboter von hinten teil lackiert

Parts are mounted on the bike

Hugo Roboter lacht 700

Ready for the first test drive

hugo der sprechende Roboter auf rotem Fahrrad mit kindern

First trip to the playground


The construction of Hugo, the remote-controlled robot was long and lasted about 3 years. That depended on the one hand to the fact that I did not work full-time on the project. In addidtion we had various challenging constructions that were developed by trial and tinkering. This takes time. Many things like lasercutting and soldering I had to learn. Especially I had to admit that you can’t make yourself everything. In many areas, you get better results when you get the help of professionals. But bit by bit you realize that you can learn everything – if you invest the time and energy.

Let me know what you think.