A Passive Elastic-Folding Mechanism for Stackable Airdrop Sensors
Damyon Kim, Yuichi Honjo, Tatsuya Iizuka, Naomi Okubo, Naoto Endo, Hiroshi Matsubara, Yoshihiro Kawahara, Naoto Morita, Takuya Sasatani
AI summary
Problem
Existing airdrop sensor networks rely on active actuators for mid-air shape control, increasing power consumption, cost, and complexity while limiting stackability and scalable deployment.
Approach
The authors developed a passive elastic-folding hinge by laminating rigid PCBs with a thick heat-shrink polyolefin sheet and polyimide, which self-folds upon a single oven-heating step and passively springs back to a 3D glider shape upon release.
Key results
- Predictive geometric model accurately links PCB gap geometry to fold angles (±4° error)
- Hinge demonstrates high repeatability, elastic recovery, and durability under cyclic deformation
- Prototype glider sensor successfully collects and transmits environmental data via LoRa during flight
- Trajectory simulations show sensors disperse over a 10 km diameter area from 10 km altitude
Why it matters
Enables low-cost, scalable, and power-efficient wide-area environmental monitoring through radiosonde or UAV airdrop networks.
Abstract
Air-dispersed sensor networks deployed from aerial robotic systems (e.g., UAVs) provide a low-cost ap- proach to wide-area environmental monitoring. However, ex- isting methods often rely on active actuators for mid-air shape or trajectory control, increasing both power consumption and system cost. Here, we introduce a passive elastic-folding hinge mechanism that transforms sensors from a flat, stackable form into a three-dimensional structure upon release. Hinges are fabricated by laminating commercial sheet materials with rigid printed circuit boards (PCBs) and programming fold angles through a single oven-heating step, enabling scalable production without specialized equipment. Our geometric model links laminate geometry, hinge mechanics, and resulting fold angle, providing a predictive design methodology for target configura- tions. Laboratory tests confirmed fold angles between 10◦and 100◦, with a standard deviation of 4◦and high repeatability. Field trials further demonstrated reliable data collection and LoRa transmission during dispersion, while the Horizontal Wind Model (HWM)-based trajectory simulations indicated strong potential for wide-area sensing exceeding 10 km.