/PB29 — a robot learning to draw

PB29 is an ongoing drawing project that grew from my painting practice. I am building it around a 7-axis robot arm in my Berlin studio, teaching the machine to see paper, locate a pen, plan a path, and make a physical mark where the plan says it should.

The system keeps its work visible: camera evidence, calibrations, toolpaths, failures, and finished drawings. The point is not a robot that magically makes images. It is a machine whose way of seeing and drawing can be inspected.

01 / studio record — july 2026

The arm, in motion

The arm now makes registered pen drawings on 300 × 300 mm paper. These five studio views show recent runs: generated line studies, a portrait test from above, and the nib working at close range.

02 / recent work

Drawings from the studio

Each study begins as geometry, becomes a checked toolpath, and is drawn on paper by the arm. The finished sheet keeps the small deviations of the machine: wobble, stick-slip, and the dark dots left by a loaded nib.

Flow-field lines parting around a small drawn robot figure — Meander. A flow field parts around a small robot figure.

The figure up close: one continuous path, a few centimetres tall.

Dense spiral disc drawn by the robot in ink — Spiral disc. Near-parallel passes turn small placement errors into texture.

Concentric wavy ring drawing — Maurer rings. Browser-generated geometry, translated into a pen path.

Green looped rosette drawn with a marker — Loop rosette in green marker. Dark dots show where the loaded nib paused.

Single continuous scribbled line drawing — One-line study. One unbroken path, with the stick-slip left visible.

03 / the rig

The current rig

The arm is a UFactory xArm 7. Around it I built a compliant pen holder, a fixed overhead camera, a magnet-registered steel drawing bed, and a 3D-printed touch station. Each part is calibrated against the others with photographs and saved measurements.

Most of the work lives between picture and mark: finding the paper, locating the nib, choosing contact height, and checking every move before the arm runs it. The failures and exact safety constraints live in the technical PB29 context.

The xArm 7 with pen holder in the studio, a painting on the wall behind — The arm in the studio. Behind it, a work from the hand-painting practice PB29 grew from.

Close-up of the pen held in the printed flexure mount — The pen sits in a printed flexure, giving it a few millimetres of passive compliance at the paper.

04 / the ledger

The machine keeps honest books

Every physical change to the rig—a new sheet of paper, a nib adjustment, a camera exposure—goes into a ledger. The ledger tells the software which calibrations are still safe to trust.

On 15 July, one run logged 182 contact strokes, 14,737 contact samples, and 6.45 metres of drawn travel. A host output pipe broke after stroke 166; the saved trace resumed at stroke 167. My verdict, also kept in the ledger: "kind of decent."

{"event_type": "paper_retape", "note": "Replaced 300x300 mm magnetic drawing paper after PB29 Phyllotaxis 63276; fresh vision XY required"}

{"event_type": "camera_exposure_change", "note": "Locked overhead exposure reduced for reflective magnetic paper detection"}

{"event_type": "nib_change", "note": "Nib adjusted before cone TCP recalibration; tool TCP XY and paper contact Z require revalidation"}

3D-printed cone touch station with a fail-safe switch — The cone station. The accepted four-yaw solve on 15 July placed the pen tip at (+23.356, +12.078, +153.702) mm from the flange.

Work Louder macro pad used to jog the robot by hand — The Work Louder pad controls manual jogs through one exclusive motion worker. The hardware emergency stop remains separate.

05 / current chapter

Portraitautomat

For decades, Berlin's Photoautomaten have made the city's most direct portraits: step in, four flashes, a strip drops out. Portraitautomat asks what that machine becomes when the illustrator is a 7-axis arm and the path from photograph to ink stays visible.

The first portrait studies are now on paper. They begin as explicit face parameters, become SVG paths, and run through the same calibrated drawing stack as the abstract work above. The self-serve camera flow is the next layer.

Long-haired generative portrait drawn in black ink — One drawing run, compressed to seconds. Three physical studies from the same afternoon.

Finished generative portrait drawn in black ink on paper — One drawing run, compressed to seconds. Three physical studies from the same afternoon.

browser study / face study 1

128 paths5,105 points

PB29 / seed 001889