Research On Motion Control And Reliability Of Mini Underwater Vehicles

Miniaturization is one important direction for autonomous underwater vehicles in the future. Due to small volume, excellent maneuverability and invisibility, low energy consumption, low resistance, high ability to avoid obstacles, there is a good prospect for Mini autonomous underwater vehicles (mini-AUVs) in the fields of military communication, marine mining and expedition and so on. For mini-AUVs with fins, the research on motion control and reliability is needed be developed and perfected.In this thesis, the research object is certain mini-AUV. Firstly, we build the motion model in six-degree freedom and analyze the force and hydrodynamic coefficients, especially the fin effective action, and the simulation system with semi physical function is established. PDCE motion control system architecture for the AUVs and the ingredients are discussed in detailed. The unit of object order explanation is proposed based on considering thoroughly motion ability of the mini-AUVs, and the object orders which can be carried out directly are obtained. The force allocation function based on rudder-wing-propeller polar control is introduced, so we adopt pitch and velocity control to achieve depth control. Owing to small size and few force devices, motion control of the mini-AUVs is lacking-freedom control. So we propose improved particle swarm optimization (PSO) to optimize the parameters of S surface control, and the performance is satisfied. Moreover, we propose a novel control method bases on generalized sigmoid fuzzy neural network (SFNN) to improve the maneuverability and the ability to avoid obstacles. The experiment results verify the feasibility and superiority. Finally, reliability evaluation and reliability analysis are carried out for the motion control system. General evaluation method based on Bayes thought is proposed carried out reliability evaluation. Fault tree analysis is introduced to carry out reliability analysis to evaluate the reliability level of the motion control system and analyze the weakness of each ingredients, so we can give some improved advice.