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 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.

Hydraulic structures (such as dams and aqueducts) can suffer from damages, such as cracks and collapse due to natural aging as well as the impact of natural disasters (such as earthquakes and floods). Determining underwater damage is generally not easy because of significant concealment and safety hazards. Remotely operated vehicles (ROVs) have gradually become capable assistants for the regular underwater maintenance of hydraulic structures. With disturbances from undercurrents and propeller reactions, achieving precise positioning of ROVs has always been a complicated technical problem, and it is also one of the important factors affecting underwater inspections and repair accuracy. To address the environmental disturbances during ROV dynamic positioning, a fuzzy predictive control algorithm combining fuzzy control and model predictive control is proposed in this paper. This algorithm can dynamically adjust the power output of propellers in real-time according to the undercurrent data measured by sensors and carry out differential correction until the ROV reaches the predetermined position. Moreover, the aim of this paper is to analyze disturbances in the longitudinal (X), lateral (Y), and depth (Z) directions during the motion of the ROV. The parameters are adjusted through the algorithm to simulate the dynamic positioning of the ROV's spatial movements. By setting different external environmental conditions, the power adjustment strategy and different dynamic positioning performances of ROVs can be obtained to enhance the adaptability of ROVs in complex environments and their stability in underwater inspection and repair and improve their underwater operation quality and efficiency.

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.