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BNJMN – “Mobile sensory image production mechanism”

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Created by Danilo Wanner & Travis Purrington, two students of Master Studies in Iconic Research at the Basel Academy of Art and Design (HGK), BNJMN (pronounced Benjamin) is a “mobile sensory image production mechanism”. His sole purpose is to create original artworks by roaming in search of paper, painting whatever he wants, and signing it before he moves on to start the cycle again.

The device utilises Arduino program combining synchronized hardware with coded parameters, programs and a random action function to develop an Expressive Output Cycle (EOC). On board, BNJMN has 5 servos and two sensors for his operating procedure. Two independent servos for two front wheels enable transportation while a third pivoting wheel keeps him stable. He can move straight ahead or make turns by rotating the two servos at different speeds and directions.

His two aluminum arms were constructed and synched to the output program and move two brushes on and off the paper. They were designed with a joint and spring system to control the pressure and therefore line style of each mark. Each arm is powered by a corresponding servo attached to the internal structure of the chassis. A fifth servo operates his moving antenna which is situated at the front of the casing below BNJMN’s body and arms. At the tip of the antenna sits a light sensor and a touch sensor (so he can turn around when encountering a wall or obstruction). It’s construction is from the same aluminum tubing as the arms. the light sensor consists of a single white LED and a photoresistor. They are situated side by side and both point straight down to receive light value information acquired from the floor. Depending on the amount of reflected light gathered, he sees and recognizes paper by running a an initial search protocol in his preliminary program function. To assure that BNJMN can tell paper from ground, he always begins his search process with a calibration programm when swiched on. His holder (assistant) provides him a particular piece of paper when he asks for it with a distinct swipe of the antenna over the ground. He then will look for paper with the same brightness value. (kind of like a visual bloodhound)

BNJMN’s brain is an Arduino UNO board with a ATmega328 micro-controller. Some 9V Batteries allow him to work remotely and keep him going. A on-off switch is integrated into the sleek laser-cut body that can easily be opened for power exchange thanks to its two-part “shell” design. This is also useful for maintenance, since BNJMN needs new juice, as well as some love and care from time to time.


436 lines of code define BNJMNs character by synchronizing the servos and sensors to his defined tasks. Once activated and calibrated, he starts his search for a canvas. He roams using servo rotation information from the wheels to look for suitable substrates on floor with his rambunctious antenna. When he finds one, he goes into scan mode. He analyzes an initial measurement of each paper according to his hardware properties. First he swipes with his antenna from left to right, then he travels across the paper to determine a sufficient length. When he is satisfied (he can be quite choosy since he needs space to express his explosive compositions), he arranges himself towards the middle of the paper and begins his Expressive Output Cycle by placing his two painting arms in the “painting” position.


His painting is based on random movements derived from his EOC. He changes the pressure and movement of each arm/brush combination independently allowing endless combinations of the two. This varies heavily from painting to painting assuring each is a unique and random work of the moment. He even checks from time to time if he is still on the paper…often pausing in what appears to be a contemplation of his next stroke. Once his random creation sequence has been satisfied, he concludes the EOC. His program allows freedom for any composition ranging from complex expression to supreme minimalism. BNJMN then concludes each work by signing the paining in the bottom right (if he finds it) in the age-old symbolic ritual of authorship. Sometimes he signs the floor (of course a robot doesn’t mind such minor details) and continues off on his merry way to create more art.

Created by Danilo Wanner & Travis Purrington for the ‘Drawing Machines’ workshop given by Ludwig Zeller at the Visual Communication Institute of the Academy of Art and Design in Basel.

bnjmn.chBasel Academy of Art and Design | Interaction Seminar