In context
Underwater soft actuators are increasingly used for delicate tasks like biological sampling and cultural relic salvage, but their lack of proprioception limits autonomy. Traditional sensing modules are rigid, bulky, and sensitive to temperature and electromagnetic interference, making them unsuitable for soft structures. This work addresses the need for soft, embeddable sensors that can operate in deep-sea conditions.
What was reported
Researchers from the Chinese Academy of Sciences integrated flexible optical waveguide sensors into a bellow-structured soft actuator to provide proprioceptive feedback. The sensors are insensitive to temperature and electromagnetic interference, respond quickly, and exhibit high linearity. Two sensors were embedded on the sides of the actuator to minimize impact on its dynamic performance.
In shallow-water tests, the actuator detected a 1 mm amplitude sawtooth surface at a driving pressure of 40 kPa. At pressures above 30 kPa, it could clearly distinguish its bending state and differentiate three objects of varying hardness. The sensor output correlated well with bending curvature, showing high sensitivity (0.34–0.69 dB/m⁻¹) and linearity in the 0–20 m⁻¹ range.
Under simulated hydrostatic pressures from 0 to 30 MPa (equivalent to 3000 m depth), the sensor accurately characterized different bending states, though hysteresis increased and sensitivity decreased with rising pressure. The results confirm the actuator's capability for in-situ underwater perception down to 3000 m.
Why it mattered
This work demonstrates a practical approach to embedding soft, interference-immune sensors in soft actuators for deep-sea applications, potentially enabling more autonomous underwater manipulation and inspection without bulky, rigid sensing modules.
“The proprioceptive soft actuator based on the flexible optical waveguide has the function of underwater in-situ perception, and still has good perception performance in the equivalent underwater 3000 m operating range.”
Source: 《机器人》期刊 (robot.sia.cn) · Published 2024-03-27 · “基于柔性光波导的水下本体感知软体执行器”