Due to the excellent maneuverability and obstacle crossing of legged robots, it is possible for an autonomous legged wall-climbing robots to replace manual inspection of ship exterior panels. However, when the magnetic adsorption legged wall-climbing robot steps on the convex point or convex line of the wall, or even when the robot missteps, the robot is likely to detach from the ferromagnetic wall. Therefore, this paper proposes a tactile sensor for the legged magnetic adsorption wall-climbing robot to detect the magnetic adsorption state and improve the safety of the autonomous crawling of the robot. The tactile sensor mainly comprises a three-dimensional (3D)-printed shell, a tactile slider, and three isometric sensing units, with an optimized geometry. The experiment shows that the triboelectric tactile sensor can monitor the sliding depth of the tactile slider and control the light-emitting device (LED) signal light. In addition, in the demonstration experiment of detecting the adsorption state of the robot's foot, the triboelectric tactile sensor has strong adaptability to various ferromagnetic wall surfaces. Finally, this study establishes a robot gait control system to verify the feedback control ability of the triboelectric tactile sensor. The results show that the robot equipped with the triboelectric tactile sensor can recognize the dangerous area on the crawling wall and autonomously avoid the risk. Therefore, the proposed triboelectric tactile sensor has great potential in realizing the tactile sensing ability of robots and enhancing the safety and intelligent inspection of ultra-large vessels.

An enormous number of wireless sensing nodes (WSNs) are of great significance for the Internet of Things (IoT). It is tremendously prospective to realize the in-situ power supply of WSNs by harvesting unutilized mechanical vibration energy. A harmonic silicone rubber triboelectric nanogenerator (HSR-TENG) is developed focusing on ubiquitous constant working frequency machinery. The unique design of the strip serving as a flexible resonator realizes both soft contact and high and broadband output. The significant factors influencing the 1^st-order vibration mode of the strip are developed for realizing the harmonic frequency adaptation to external vibration. The surface treatment of the strip improves the output performance of HSR-TENG by 49.1% as well as eliminates the adhesion effect. The HSR-TENG is able to achieve a voltage output bandwidth of 19 Hz under a vibration strength of 3.0, showing its broadband capability. The peak power density of 153.9 W/m³ is achieved and 12 × 0.5 W light-emitting diodes (LEDs) are successfully illuminated by the HSR-TENG. It can continuously power a temperature sensor by harvesting the actual compressor vibration energy. In brief, the HSR-TENG provides a promising way for constant frequency vibration energy harvesting, so as to achieve in-situ power supply for the WSNs in the vicinity.

Wind energy is a promising renewable energy source for a low-carbon society. This study is to develop a fully packaged vortex-induced vibration triboelectric nanogenerator (VIV-TENG) for scavenging wind energy. The VIV-TENG consists of a wind vane, internal power generation unit, an external frame, four springs, a square cylinder and a circular turntable. The internal power generation unit consists of polytetrafluoroethylene (PTFE) balls, a honeycomb frame and two copper electrodes. Different from most of the previous wind energy harvesting TENGs, the bouncing PTFE balls are fully packaged in the square cylinder. The distinct design separates the process of contact electrification from the external environment, and at the same time avoids the frictional wear of the ordinary wind energy harvesting TENGs. The corresponding VIV parameters are investigated to evaluate their influence on the vibration behaviors and the energy output. Resonant state of the VIV-TENG corresponds to the high output performance from the VIV-TENG. The distinct, robust structure ensures the full-packaged VIV-TENG can harvest wind energy from arbitrary directions and even in undesirable weather conditions. The study proposes a novel TENG configuration for harvesting wind energy and the VIV-TENG proves promising powering micro-electro-mechanical appliances.