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We present a real-time optimization method for autonomous vehicle motion planning. Trajectory optimization is essential for autonomous vehicle motion planning, due to its non-holonomic motion. Conventional way of optimization is by trajectory smoothing. In this paper, we use differential dynamic programming (DDP) to optimize the trajectory. The key advantage of DDP is that it not only smoothes the trajectory but also considers the non-holonomic constrain of the vehicle. The optimized trajectory is pre-proof to be able to executed by the vehicle. Results are demonstrated with an autonomous vehicle model in Gazebo simulation environment.

To investigate the influence of additional device on the flow in marine current turbine, two additional devices for marine current turbine including short diffuser and long diffuser types are studied based on the test data of original marine current turbine. The results of numerical simulation show that the additional device with flange structure, compared to marine current turbine without additional device, can obtain more output power. However, it brings the inhomogeneity of additional device force as the increasing of effective output power. At same time, due to existence of the flange, two karman vortices are found behind the flange. The low pressure region produced by additional device and flange structure can speed up the flow around the marine current turbine, so as to improve the output power.