The wave glider is an unmanned surface vehicle propelled by waves. It consists of a surface float, a submarine glider, and a tether. The submarine glider is the main drive of the wave glider and converts vertical motions into forward thrust. The tether is responsible for the force transfer between the float and the submarine glider. The motion performance of the submarine part of the wave glider plays a crucial role in energy absorption efficiency and navigation performance. To accurately model the submarine part, a mathematical model of the submarine glider and tether is established using the Newton-Euler approach. Hydrodynamic experiments were conducted with respect to the submarine glider to improve the accuracy of the model. Meanwhile, motion experiments are carried out on the wave glider to validate the model. The results show that the error between the simulation and the experimental results is less than 5%. The model lays a foundation for the high accuracy motion simulation of the whole wave glider. Furthermore, the model can be used to optimize the design parameters of the wave glider and improve its speed.
With the continuous exploitation and depletion of land resources, there is a growing interest among humans in understanding and observing the ocean. This has led to the development of various new ocean observation equipment. One such equipment is the wave glider, which is comprised of a surface float, a submarine glider, and an umbilical tether. Its unique mechanical structure enables the wave glider to convert a continuous flow of wave energy into horizontal kinetic energy (Hine et al., 2009). Due to its special structural design and energy conversion mode, many scholars have conducted extensive research on the motion performance of the wave glider. Smith et al. (2011) established a calculation formula to predict the motion speed of wave gliders according to the Marine environment. Liu et al. (2016) simulated the thrust performance of the hydrofoils of a wave glider in different waves and verified it by experiments. Li et al. (2017) established a wave glider dynamics model to simulate the motion of the wave glider, and verified the reliability of the simulation model with the results of sea trials. Thaweewat et al. (2018) conducted a simulation on the hydrofoil of a wave glider to investigate the effects of swing frequency and spring stiffness on its propulsion performance. Wang et al. (2019) developed a 4-degree-of-freedom motion simulation model for the wave glider, enabling the simulation of its motion in complex marine environments. Tian et al. (2020) integrated flexible webbed wings (FWWs) into the design of the wave glider, establishing an improved dynamic model and conducting simulation research. Experimental verification demonstrated the feasibility of this approach. Rozhdestvensky (2022) derived the motion equation of the wave glider and employed a simplified model to simulate the impact of various design parameters on its propulsion performance. Xie et al. (2022) proposed a novel hydrofoil design to enhance wave energy conversion efficiency in wave gliders. The propulsion effect was estimated, and hydrofoil design was optimized using computational fluid dynamics (CFD) method to improve the overall performance. Thomas et al. (2023) utilized the ASVLite simulator to simulate the motion of a wave glider, validating the model against long-term ocean voyage data, thus confirming its reliability.
