Crawling
under
my skin
Soft pneumatic arm on a wall.
Senses its environment. Responds.
the concept visualised · after one week of phase 1
Aim
- soft pneumatic arm on a wall
- senses its environment: people, sound, light
- decision layer filters the input
- the arm responds
Phase 1: material · printing · motion
skin and decision layer: later phases
Concept and theory
sensory intelligence
senses and responds through the arm
filter + overlap
what counts, what collides
response
how the arm answers input
extended mind
Clark, Chalmers
the mind reaches into tools
soft assembly
Clark
simple local rules, behaviour emerges
perception through the body
Merleau-Ponty
the body shapes what is sensed
Body
- octopus-like arm, thick at wall
- pneumatic: chambers, pump, valves
- soft body: cast or printed
- exposed spine below the arm
- one vertebra per chamber
- form not final
arm base
three chambers
valves x3
one per chamber
esp32
sensing, relays, logging
pump
damped feet
12 v
mains enclosed
Sensing
people
proximity, direction, touch
conductive thread zones, or hidden module
someone close → arm responds
sound
loud events, voices, room
microphone: level, onsets
too loud → pulls back
light
on, off, dim
light sensor
lights off → sleep mode
All open. Also: temperature, vibration. Strip test decides thread or module.
refs: Silva-Plata 2025 (touch stays stable under deformation) · Zahir 2026 (yarn proximity 40–60 mm) · capacitive yarn on a soft robot
Sound
I mechanical
pump, valves, air
II ambient
the room, quiet
III human
voices near the wall
Drawings: level over time, not audio. Features only. Pump masked while running.
Data flow
sense
environment
read
ESP32, features
decide
filter, overlap, rule set
switch
relays, valves
move
pump, arm
log
CSV, features only
lab
rule sets compared
Body prototypes
EXPERIMENTS · THREE CHAMBERS AT 120° EACH · NOTHING MADE YET
P1
cast
- printed mould, cast
- tapered, 3 chambers
TeMoG 2021 · OpenSCAD moulds for three-chamber tentacles
Papadakis 2024 · octopus arm, Ecoflex 00-10, PLA moulds
P2
printed TPU
- printed in one piece
- bellows chambers
Moratuwa 2025 · monolithic printed TPU, three independent chambers
Meitani & Nisar 2025 · TPU 60A / 70A, 100–300 kPa
P3
strain layer
- wrap on P1 or P2
- thread, fabric, fibre
SoPrA 2021 · fibre-reinforced chambers, tapered section
Festo OctopusGripper 2017 · Lycra around silicone limits swelling
Xie 2020 · taper angle tunes curvature
P4
bundle + fill
- 3 printed tubes, filled
- centre channel for air
SoPrA 2021 · three chambers bundled, silicone poured around
Oxford modular actuator · centre channel for pneumatic lines
COMPARE · BEND · FORCE · SPEED · CYCLES · BURST · SAG
details if asked
- Ecoflex 00-10 to 00-50; harder silicone needs 5–6 bar vs 1–2 bar (Papadakis)
- TPU 60A or 70A, not 85A; worked at 100–300 kPa; about 10 h per print; dry filament first (Meitani)
- TPU gripper vs silicone gripper: 5× load, 2× bend (a gripper, not an arm)
- resin can block silicone cure: cure test first
- three chambers 120° apart bend in any direction (IJRR soft-arm bending)
- no source combines taper + 3 chambers + printed TPU: the prototypes combine pieces
- details are from abstracts and search summaries: open the papers before citing
Motion
reach
pause
retract
measure: pressure → bend angle, tip position, speed
set: hold time, distance, retract speed
reference: 10 ms pulses, 0.1–0.5 bar, up to 24% elongation (Papadakis 2024). Valves on/off, so motion is stepwise.
Previsualisation and next steps
[ render: arm and spine on a wall, visitor approaching ]
NEXT TESTS · NO RESULTS YET
01
material route
cast vs printed
02
single chamber
pressure → bend
03
one electrode
thread on a strip
04
one sound test
level, onsets
Wall height, arm length, room: undecided. Failures count as results.