Go Back

Not so Close!

Team member(s): and
Modified by on

A kinetic leaf that folds and opens as you reach for it. Some facades follow the sun. This one watches you. Reach for it, the leaves fold away. Step back, they slowly open again. Inspired from the touch-me-not plant, built from two stepper motors, two laser-cut planetary gearboxes and a pair of strings that never quite agree.

Fig.1 Caught mid-flinch: two pinnae, eight leaflet pairs each, all hanging off one winding shaft.

Concept

Kinetic facades are usually weather oriented. They track the sun, sniff the wind, react to humidity. ‘Not-so-close’ is a people person, just a slightly shy one. This prototype reacts within 25 cm and its leaves fold away, leave it alone and they open again, exactly what the plant Mimosa pudica does when someone pokes it. Touch a leaf and within seconds its leaflets snap shut in pairs. The faint is a defense mechanism.

The Question :

what if a building skin reacted to the person standing right next to it, at arm’s length, instead of to a timer or a weather station creating a facade with personal space?

Look, don’t touch. Actually, don’t even reach.

Fig.2 Idea on paper : get within 25 cm and the ultrasonic sensor notices, the stepper motor winds the spool and gears, and the leaf folds away.

Schematics

The circuit connects an ultrasonic sensor and two stepper motors to Arduino UNO.

The ultrasonic sensor is the input and the stepper motors are the output.

When an object comes within 25 cm, The Ultrasonic motion sensor detects and sends signal to the Arduino circuit board , The output instructs the motors to spin clockwise for 5 rotations. The motors turn the planetary gears, which in-turn rotates the axle and folds the leaves. When the object moves away, the motors spin anti-clockwise back to its original position and the leaves opens again.

Fig.3 Schematic wiring diagram of the prototype

Exploded view – Prototype

Fig.4 Exploded view of the prototype

The exploded view shows how the parts join, from the motors up to the leaflets:

  • Stepper motor: drives each gearbox.
  • Back plate: holds the motor and the ring gear.
  • Ring gear: fixed, with teeth on the inside.
  • Sun gear: sits on the motor shaft and turns the planets.
  • Planet gears (×3 per gearbox): roll around inside the ring gear.
  • Carrier: turns with the planets and drives the winding shaft.
  • Drum: sits on the winding shaft and winds the strings.
  • Hex axle: turned by the strings, it rotates the leaflets.
  • Leaflet: folds up when the axle turns

Electronics – Bill of quantities

Fig.5 Bill of quantities

Code

Prototype

Fig.6 Working of gears

‘Not so fast‘ …. – Video Demonstration

Tags: , ,

Not so Close! is a project of IAAC, Institute for Advanced Architecture of Catalonia developed in the Master in Advanced Architecture - 2026-2027 by the student(s) and during the course MAA01 26/27 Introduction to Programming and Physical Computing Seminar with Daniel Mateos, Angel Muñoz, Adai Suriñach, Antoine Jaunard and Akshay Madapura.