Summary
The power supply for ocean robots has always been an important issue since it has a fatal influence on the endurance of these vehicles. However, the marine renewable energy (MRE) has huge potential and can provide the possibility to solve this problem between essential endurance and finite energy in ocean robots. This paper starts with brief introduction of marine energy resource and ocean robots and presents significance of improving ocean robots' endurance, through comparison of their performance characteristics. MRE applied in ocean robots developed or under development, including energy conversion and driving principle, is reviewed, such as solar, wind, tides, waves, thermal energy, etc. Many challenges and difficulties are also discussed in energy exploitation and utilization related to ocean robots. Finally, the prospect for the future development of related technologies is proposed in this paper.
Wave driven unmanned surface vehicle (WUSV) is a new concept ocean robot drived by wave energy and solar energy, and it is very suitable for the vast ocean observations with incomparable endurance. Its dynamic modeling is very important because it is the theoretical foundation for further study in the WUSV motion control and efficiency analysis. In this work, the multibody system of WUSV was described based on D-H approach. Then, the driving principle was analyzed and the dynamic model of WUSV in longitudinal profile is established by Lagrangian mechanics. Finally, the motion simulation of WUSV and comparative analysis are completed by setting different inputs of sea state. Simulation results show that the WUSV dynamic model can correctly reflect the WUSV longitudinal motion process, and the results are consistent with the wave theory.
Wave-driven unmanned surface vehicle (WUSV) is a great success of application of solar and wave energy in the ocean robot. In this paper, the nonlinear dynamic model of WUSV in two dimension is established based on the analysis of its driving principle in the longitudinal profile. Then, we calculate the wave and driving force, and determine hydrodynamic coefficients according to the empirical data and experimental platform of WUSV. Finally, we simplify the nonlinear equations and present the simulation results of the model.
Wave-driven unmanned surface vehicle (WUSV) is a new concept marine robot drived by wave energy and solar energy, very suitable for the observing vast oceans with incomparable endurance. Firstly, the multibody system of WUSV is described based on D-H approach and the velocity and position of each moving part in WUSV are represented. Then, the driving principle is analyzed and the WUSV dynamic model in three dimension is established by lagrangian mechanics. Finally, we perform the motion simulation of WUSV under certain sea conditions. These tasks provide the theoretical foundation for further study on the WUSV motion control and efficiency analysis.
In this paper, the data feature of depth-averaged current velocities (DACVs) derived from underwater gliders is analyzed for the first time. Two features of DACVs have been proposed: one is the complex ingredients and small samples, and the other is the stationarity that occurs as the length of a DACV sequence increases. With these features in mind, a set of methods combining statistical analysis and machine learning are proposed to realize the prediction of DACVs. Four groups of DACV data of different gliders from sea trials in the South China Sea are used to verify the prediction method. Based on three general error criteria, the prediction performance of the proposed model is demonstrated. The persistence method is used as a comparison model. The results show that the prediction methods proposed in this paper are effective.
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