Hydrokinesis

Jiayi Ye '27

Precise control of floating objects on water surfaces holds significant impact in various fields, including water conservancy engineering, environmental management, and intelligent waterborne transport system design. However, traditional methods primarily rely on mechanical arms, robots, and wind to control the moving trajectory of the bulky objects and are limited in control precision and the handling of small-sized floating objects. Additionally, these methods could only be applied in specific situations and cannot be used in complex aquatic environments or confined spaces, which detracts from the overall flexibility and practicality of the system.

To improve the efficiency and precision of surface water operations, scientists around the world have begun to explore non-contact manipulation techniques. In 2014, researchers from the Australian National University developed a technique using complex waveforms to generate surface wave patterns capable of exerting directional forces on floating objects (Australian National University, 2014). This approach demonstrated the feasibility of manipulating objects without physical contact by precisely controlling the wave characteristics on the water surface. Building upon the previous non-contact system control method, a research team led by Jacquart in 2023 invented a way to control floating objects by generating water flows through mechanical fin movements (Jacquart, Obayashi, & Hughes, 2023). The system enabled targeted object transportation across a confined water area and highlighted the potential of hydrodynamic manipulation for soft robotics and autonomous systems. In 2024, researchers at the Swiss Federal Technology Institute of Lausanne proposed the use of acoustic fields to guide floating objects around obstacles, which relied on generating localized pressure gradients in the water (Ecole Polytechnique Fédérale de Lausanne, 2024). These studies collectively illustrate the development of alternative, non-contact techniques for controlling floating objects in fluid environments.

Although these new methods have made progress in specific scenarios, most of these techniques are limited by their reliance on particular physical media, such as conductive liquids or magnetic materials. Yet, universality, stability, and the ability to scale across different application levels are also important factors to consider when evaluating the methods. Coming up with a generalized, non-contact method of controlling arbitrary floating objects in open water environments has become one of the greatest challenges in current surface manipulation research.

A 2025 Nature publication solved these problems. A research team from Nanyang Technological University, in collaboration with international research institutions, creatively designed a non-contact guidance method for floating objects on water surfaces based on controlling structured water waves with high precision (Technique to Manipulate Water Waves to Precisely Control Floating Objects, 2025).

Unlike traditional approaches that rely on external devices or specific material, this method simply relied on the physical structure of liquid. By generating stable and tunable waveforms, the controlling system drives floating objects along specific paths toward designated locations. This approach significantly reduces system complexity, enhances control stability, and can operate in ordinary water bodies, which improves its universality. By overcoming the traditional limitations related to site conditions, physical parameters, and target object types, this method opens up new possibilities for practical applications in diverse real-world environments. In the journal, the research team employed a combination of low-frequency oscillators and 3D-printed waveform control elements to generate water waves of specific shapes to simulate the
operation scenarios in real life. These waves, through interference and superposition, formed stable structured wave fields on the water surface, creating directional flow paths with "tractor-like" guiding capability. In the experiments, foam spheres with diameters of approximately 2–3 millimeters, representing light floating objects, were placed on the water surface to simulate the motion responses of floating debris or micro-carriers in real-life environments (Technique to Manipulate Water Waves to Precisely Control Floating Objects, 2025). By adjusting the oscillator’s frequency and amplitude, along with the geometric shape of the control elements, the team achieved precise modulation of the wave field patterns. Their success allowed the foam spheres to move stably and repeatedly along predefined trajectories such as spiral, circular, and linear paths, illustrating the system’s strong control performance and scalability.

Despite the scientific advances in water wave drive control, there are still areas for further development, such as connecting the system with control mechanisms; applying this method to biological operations; improving the control algorithm to achieve more complex path planning and obstacle avoidance capabilities; and using the technique to design active collect system for water pollutants. Overall, the non-contact manipulation of floating objects can hold the key to solving many real-life, fluid-based problems.


References

Australian National University. (2014, August 10). Water tractor beam: Complex waves generate flow patterns to manipulate floating objects. ScienceDaily. Retrieved April 21, 2025 from www.sciencedaily.com/releases/2014/08/140810214202.htm
Nanyang Technological University. (2025, March 11). Technique to manipulate water waves to precisely control floating objects. ScienceDaily. Retrieved April 21, 2025 from www.sciencedaily.com/releases/2025/03/250311122823.htm
Jacquart, S., Obayashi, N., & Hughes, J. (2023). Non-contact robotic manipulation of floating objects: Exploiting emergent limit cycles. Frontiers in Robotics and AI, 10. https://doi.org/10.3389/frobt.2023.1267019
Ecole Polytechnique Fédérale de Lausanne. (2024, June 5). Researchers move floating objects with Soundwaves. Researchers move floating objects with soundwaves.
https://phys.org/news/2024-06-soundwaves.html