Research On Buoyancy Regulating System And Depth Control Technology Of Underwater Vehicle

As more attentions have been put into the ocean resources and the acceleration of ocean development, the autonomous underwater vehicle(AUV) technology, which is the most effective tool for ocean exploration, has been developed rapidly. The deep submergence, long-range, multi-functional, and intelligent AUV have been the future trend. Oil capsule buoyancy regulating system is used as the variable ballast unit of the deep submergence and long-range AUV. It plays a vital role in replacing the vertical propeller, non-power potential floating, buoyancy fine-adjusting of definite depth, and posture adjusting, etc, in complex ocean environment. And the system can reduce energy consumption and improve the effective working time. Therefore it is significant and using valuable to do the research work of buoyancy regulating system and the system-based AUV heave motion control technology. In this paper, the buoyancy regulating system of AUV and AUV heave motion control technology was studied. The main research contents include:(1) The research of buoyancy regulating technology of AUV both in domestic and abroad was analyzed. And the issue of buoyancy change control accurately of AUV was studied. An new oil capsule buoyancy regulating system design was proposed, and an experimental prototype of the buoyancy regulating system design was developed.(2) The relationship between working pressures and pump displacement of buoyancy regulating system was studied. The power consumption of buoyancy regulating system under different pressures was analyzed. Through the relationship curve of pressure-pump displacement and pressure-power obtained by experiments, it provides reference for the analysis of energy consumption during the AUV unpowered heave motion. (3) The measurement method of AUV buoyancy regulating system was studied. Because of the question that the buoyancy measurement accuracy decreased with the increase in working hours owing to the accumulated error of constant rate pump buoyancy measuring and turbine flow meter measuring, an in-built immersion oil pressure sensor compensation transducer was developed, which is used to measure buoyancy of the oil capsule buoyancy regulating system. The theoretical analysis showes that this buoyancy measurement method does not produce accumulated error, and the experimental results validate the method is effective to improve the buoyancy regulation accuracy.(4) The AUV kinetic model under considering the changes in water density with depth was studied, and the kinetic model of unpowered heave motion was established. With the integration of TSK fuzzy control algorithm and non-model sliding-mode control algorithm, the sliding-mode fuzzy control method based on the sine function was proposed. In this control method, the open-loop simulation experimental data of unpowered heave motion was used to design the sliding-mode fuzzy depth controller.Aim at the wider depth overshoot of the sliding-mode fuzzy method, a variable universe adaptive fuzzy sliding-mode method was proposed. In this method, the contraction-expansion factor was imported into fuzzy control, to design the variable universe sliding-mode fuzzy depth controller. Based on the above research, the simulation experimental researches of heave motion under different controllers were carried out. And the energy consumption heave motion of AUV with different controllers was analyzed.(5) The definite depth control experimental platform and the depth control system of buoyancy regulating system were developed. The control interfaces of experimental platform were developed by VC. To assess the performance of the buoyancy regulating system and prove the feasibility and effectiveness of the theory and method proposed in this paper, the shore-based and pool experiments were carried out.