In context
In 2023, soft robotics research was rapidly expanding, with a focus on bio-inspired designs for underwater applications. Bistable structures, which can snap between two stable states with minimal energy input, were gaining attention for their potential to overcome the slow response times of soft materials. This work from the University of Shanghai for Science and Technology contributed to this trend by applying a bistable device to a squid-inspired water-jet propulsion system.
What was reported
Researchers developed a soft robot mimicking squid water-jet propulsion, driven by a pneumatic bistable device. The device, made of a TPU film air chamber bonded to an FR-4 epoxy substrate, snaps between two states as gas is periodically supplied, causing a paddle film to reciprocate and change the robot's internal volume. By adjusting the driving frequency, the robot rapidly expels water and slowly absorbs it, creating a momentum difference that propels it forward.
The team established a mechanical model of the bistable device's snap-through behavior and used ABAQUS simulations to verify its bending performance. Experiments characterized the propulsive force generated by the snap-through and its relationship with driving frequency. The prototype achieved a swimming speed of 8.7 cm/s (approximately 0.58 body lengths per second) and demonstrated a certain load capacity, indicating excellent swimming performance.
The bistable device offers a simpler structure and lower cost compared to previous designs that relied on rigid springs or linkages for pre-stretching. The manufacturing process uses a hand-held heat sealer, avoiding complex mold design.
Why it mattered
This research highlighted the viability of bistable mechanisms for soft underwater robots, offering a way to achieve high driving power and fast response without complex rigid components. The approach could inspire more efficient propulsion systems for underwater inspection, exploration, and environmental monitoring, advancing the practical deployment of soft robots in real-world aquatic tasks.
Research results show that the prototype can reach a speed of 8.7 cm/s (0.58 body length per second) driven by the bistable device, demonstrates a certain load capacity, and exhibits excellent swimming performance.
Source: 《机器人》期刊 (robot.sia.cn) · Published 2023-05-09 · “气动双稳态装置驱动的仿喷水推进乌贼结构软体机器人”