Wearable electronics, such as smart textiles, are of potential use in healthcare monitoring, human–machine interfaces and environmental analysis. However, the scalability and reliability of the technology is restricted due to challenges related to rapid material degradation, potential toxicity, high production costs and heavy computational workload. Here we report an acoustic-based smart textile technology. The approach, which we term SonoTextiles, uses piezoelectric transducers that are mounted at both ends of glass microfibres and act as transmitters and receivers of acoustic waves. The flexible glass microfibres act as acoustic waveguides and are embedded into the textile substrate, providing precise sensing by measuring wave propagation and energy loss along the fibre in response to stimuli such as touch and bending. We also use acoustic frequency selectivity and frequency-domain signal processing algorithms to enhance computational efficiency. Our acoustic textile is breathable, durable and stable under thermal fluctuations, and we show that it can be used in distributed tactile sensing, hand gesture recognition and respiratory rate monitoring.

Underwater positioning is critical to autonomous underwater vehicles (AUVs) for navigation and geo-referencing. The rapid attenuation of the electromagnetic wave in the underwater environment prevents the use of traditional positioning methods such as the Global Positioning System, whereupon acoustic methods like ultra-short baseline (USBL) positioning systems play an important role in AUV navigation. However, the high cost and complexity of classical USBL systems have stifled the democratization of these technologies, which leads to a new method called passive inverted ultra-short baseline (piUSBL) positioning. In a typical piUSBL system, a single beacon is placed at a reference point, periodically broadcasting a positioning signal. A passive USBL receiver, time-synchronized to the beacon, is mounted on an AUV to get one-way travel-time (OWTT) slant range and azimuth estimates. The passive nature of the receiver means the system is inexpensive, low-power, and lightweight. Particularly, the omnidirectional broadcasted signals offer a feasible solution for concurrent multi-AUV navigation. This letter demonstrates a full-stack design and development of a piUSBL positioning system, and presents evaluations of the accuracy and reliability of the system through a series of experiments. More significantly, a successful sea trial of a disc-shaped AUV outfitted with our piUSBL was conducted in the South China Sea.

The autonomous underwater helicopter, shortly referred to as AUH, is a newly developed underwater platform with a unique disc shape. An autonomous underwater helicopter with a suboptimal disc shape is presented in this paper. It adopts a multirotor configuration and stable fins to overcome the shape shortcoming for motion stabilization. Its motion analysis and mathematical model have been introduced accordingly. Computational Fluid Dynamics (CFD) simulation is carried out to evaluate fins’ hydrodynamic performance. Proportional integral derivative (PID) and sliding mode fuzzy (SMF) control are adopted for controller design. Finally, the controller is applied on this AUH and extensively tested in various simulations and experiments, and the results illustrate the high stabilization and robustness of the controller and the hovering stability and manoeuvrability of AUH.