Research On Depth Control Of UUV With Structure Of Three Thrusters

The unmanned underwater vehicle (UUV) with structure of three thrusters, which is simple and reliable, is a kind of underwater equipment. Its characteristic is that there are one vertical thruster for pitching and two horizontal thrusters for cruising and yawing. The structure of three thrusters shows more flexible, stable and lower power consumption than others which have the same amount of drives. The UUV based on structure of three thrusters has considerable prospect in the field of cruising.This paper studies on the depth control of UUV based on a kind of structure of three thrusters. The typical structure of three thrusters is improved in the study, which makes the UUV get pitching control ability without adding drives. The improvement changes the method of depth control of vehicle at the same time. In order to analyze the advantages of the improvement and overcome its disadvantages, this paper mainly performs several tasks.Firstly, we research on dynamics of system. A feasible scheme is proposed through analysis of present typical structures. Several tasks, including modeling of dynamics, model simulation and fluent simulation are performed step by step. The optimized parameters of improvement are calculated by the results of simulation.Secondly, the control algorithm of depth system is designed. The control strategy is presented through the analysis of control system structure. Then, a control algorithm is proposed. We designed a double-closed loop control algorithm in this paper. The pitching controller based on fuzzy sliding model control, in which fuzzy algorithm is used to eliminate sliding chattering, is designed in the internal loop and the depth controller based on fuzzy logic control is designed in the external loop. We performed simulation of system to optimize the parameters of algorithm. The feasibility of improvement of UUV is demonstrated.In order to prove actual effect of the improved structure as well as to assess the actual features of control algorithm, a complete experimental platform including a new UUV and real-time monitoring controller is finished. In this paper, the design of hardware and software are accomplished, which is discussed in detail.Finally, a series of tests, including pitching control experiment and depth control experiment are carried out in different natural water environments. The experimental results indicate that the controller is also excellent in natural condition when compared with simulation. The merits of improvement are further demonstrated.