Steady State Analysis and Optimization for AUV Using Washout Filter Root Locus Correction Method

Autonomous underwater vehicles (AUVs) are widely used in the field of ocean engineering. Steady state analysis of a AUV is considered a necessary part in the design process. A rear dual propeller vector propulsion AUV is developed in this paper. Motivated by improving the AUV stability, a washout filter-based feedback optimization methodology for AUV is presented. First, with the AUV structural parameters, a AUV four degree-of-freedom mathematical model of the motion space is calculated to provide a mathematical basis for rock-bottom steady state control systems. Second, the transfer function of the filter is derived according to the pole-zero and root locus map of the AUV system. The washout filter correction model is established based on the root locus map and is connected in series with the AUV space-state model. The simulation analysis result shows that the stability of a system is greatly increased after the whole system is connected to the filter. Finally, the AUV thrust pool test and sailing test are carried out. The experimental results show that the proposed method can improve the thrust stability of a system. This method can be applied to AUV thrust control systems.