Objectives This study aims to establish a dynamic model of wave gliders in the longitudinal profile by treating the umbilical cable as multiple hinged rigid rods, and to reveal the influence laws of environmental parameters and umbilical cable parameters on the longitudinal motion characteristics.
Methods Based on reasonable assumptions and simplifications, the umbilical cable was treated as multi-segment homogeneous and mutually hinged rigid rods. The Lagrange method was adopted to construct the multi-rigid-body dynamic model for the wave glider in the longitudinal profile. Combined with the calculation methods of wave force, fluid resistance, and external force of hydrofoils, a simulation program was developed on the Matlab/Simulink platform to solve the model. The validity of the model was verified by comparing its results with those of existing studies. Finally, a sensitivity analysis was further carried out to explore the effects of environmental parameters and umbilical cable parameters on the system response.
Results The results show that: as the wave height increases, the longitudinal motion response enhances; when the wave height increases from 0.2 m to 0.4 m, the longitudinal response increases by 78.20%. Under a current disturbance of 0.07 m/s, the longitudinal displacement within 60 s in the downstream condition increases from 1.53 m to 9.11 m compared with that in the upstream condition. As the length of the umbilical cable decreases, the longitudinal motion response enhances; when the umbilical cable length decreases from 5 m to 2 m, the longitudinal response increases by 31.97%. An excessively small wave period leads to a decrease in the longitudinal response due to rigid impacts between the multi-segment hinged rigid rods. Additionally, the change in umbilical cable density has a slight impact on the longitudinal motion response.
Conclusions The research results can provide theoretical support for the structural optimization design and motion control strategy of wave gliders.
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