Aiming at the low efficiency and high energy consumption of unmanned ships traversing the entire area, a complete coverage path planning algorithm based on the improved A-star algorithm is proposed. The positioning and vision systems of unmanned ships are used to digitize the actual water information, and the grid method is used to convert the information into an environmental map that can be planned. Compared to the trapezoidal partition of unity method and the short-side reciprocating traversal algorithm in the traversal process, experiments show that path planning is more efficient with the boustrophedon partition of unity method and the long-side reciprocating traversal algorithm. Aiming at the “dead zone”, an improved A-star algorithm is proposed on the basis of the traditional A-star algorithm, that it can shorten about 1/4 path using the proposed algorithm. Simulation shows that the improved A-star algorithm can shorten the traversal path to 40 steps but the traditional A-star algorithm needs 54 steps. Navigation test shows that the proposed algorithm can shorten the traversal path and improve traversal efficiency while ensuring the coverage of unmanned ships.

In this paper design of DC-DC boost converter with constant current control, charging is presented to charge the battery of electric vehicles. The different methods of battery charging are discussed. The charging profile of different types of batteries is investigated and compared with respect to charging time. The battery current is sensed and compared with a reference current and the generated actuating signal which is an error is feed to PI controller to compute a duty cycle of boost converter for constant current operation. A 6 V dc supply is obtained by using a step down transformer and diode rectifier. Boost converter parameters are designed for continuos conduction mode operation. The limiting values of duty cycle are fixed in the range of 0.5 to 0.6 for constant current operation. Simulation is carried out using MATLAB software for constant current operation connected to a 50 Ah, 12 V battery load. The constant current operation is achieved using negative feedback control. The switching frequency of boost converter is set to 20 kHz. The filter components are also designed to reduce ripple content within limited values. The simulation result shows the effectiveness of charging control for hardware implementation.

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