This project presents a bionic autonomous underwater robot aiming to achieve flexible

underwater mobility while minimizing disturbance to the surrounding marine environment and

supporting non-invasive observation tasks. Following a literature-informed concept generation

process, a weighted concept selection method was applied to determine both the propulsion and

buoyancy solutions. The final propulsion system adopts a quick-return tentacle actuation driven

by two crank–slider mechanisms coupled with a multi-link mechanism, enabling a more natural

extension–contraction cycle and providing the thrust pattern required for jellyfish-like locomotion.

For buoyancy control, a syringe-based water intake mechanism (crank–slider driven) was

selected to realize controllable ballast variation.

The prototype is designed for manufacturability: planar components are primarily laser-cut

(with stainless-steel reinforcement for high-stress members), while geometrically complex parts are

produced via PLA 3D printing, including modular limit tracks for assembly and tuning. The control

system follows a dual-input architecture (remote controller and web interface) coordinated by an

on-board MCU, which integrates motor actuation, LED control, camera streaming, and IMU-based

pose feedback for monitoring. Testing confirms successful reproduction of the contraction–

relaxation motion and real-time telemetry (acceleration, angular acceleration, temperature) with

basic image transmission; remaining performance limits are mainly attributed to joint and track

tolerances, motivating higher-precision bearings and improved fabrication, as well as future

depth/pressure sensing for closed-loop depth control.

Aurelia is a bionic autonomous underwater robot directly inspired by Aurelia aurita, commonly

known as the moon jellyfish—one of nature’s most elegant and efficient swimmers. The core

objective of this project is to develop an intelligent underwater platform that can achieve flexible

movement in marine environments while minimizing disturbance to the surrounding ecosystem.

The research and development of Aurelia are driven by three key motivations: first, to enable

non-invasive marine research, as conventional propeller-based underwater robot generate

substantial noise that disturb marine life and hinder close-range scientific observation, while the

project’s silent biomimetic system reduces environmental impact to facilitate such research; second,

to achieve high energy efficiency, addressing the issue of traditional underwater robots which

require continuous power input and face large water resistance leading to limited endurance by

mimicking the moon jellyfish’s efficient locomotion mechanism that leverages fluid dynamics

principles; and third, to integrate abundant sensing functions to serve as an integrated underwater

observation platform equipped with cameras, temperature sensors, pressure sensors, and other

detection devices.

In conclusion, our bionic autonomous underwater robot, Aurelia, has successfully realized its

core design objectives.

The prototype demonstrates a functional biomimetic locomotion system that closely replicates

the contraction-relaxation motion cycle of a moon jellyfish, enabling silent and efficient underwater

propulsion.

Furthermore, we have established a foundational control and sensing architecture, achieving

real-time data transmission for parameters such as acceleration, angular velocity, and temperature,

alongside basic video streaming capabilities.

Looking ahead, we plan to implement several key enhancements to advance the platform's

autonomy and operational capability. Future development will focus on integrating a closed-loop

buoyancy control system by incorporating pressure and depth sensors, upgrading the onboard

computational unit to handle more complex sensor fusion and navigation algorithms, and refining

the mechanical design to improve joint precision and motion smoothness. These improvements aim

to transform Aurelia into a fully capable, intelligent platform for sustained and non-invasive

underwater observation and research.