Motion Control For Mini Autonomous Underwater Vehicle

For the mini Autonomous Underwater Vehicle (mini-AUV) has characters of small volume, low resistance, good maneuverability, low cost and etc, it is suitable to be an unmanned, autonomous underwater device. The motion control is the basis of the development of min-AUV system, and the motion control system is the precondition for the min-AUV to finish the tasks and missions.However, because of the small volume of mini-AUV, its performance of anti-wave and current disturbances is not well, and it is a strong non-linear uncertain system. Moreover, it works in complicated ocean environment. Its motion control faces many difficulties. Furthermore, it has a few sensors. The motion information gotten from sensors is not enough to control it, so it has high requirment on the data process, control algorithm and forces allocation.In this paper, the hydrodynamic model fit for "WL" mini-AUV is perfected.This model provides a useful simulation platform for the design of the mini-AUV.This paper presents S membership function-based FNN according to the moving characters of this mini-AUV. The learning algorithm was developed.This modified FNN has simpler algorithm, higher calculation speed and improved response ability, compared with Gauss membership function-based FNN.In order to reduce the difficulties and errors brought by the parameters adjustment in S surface control, Particle swarm optimization (PSO) of S surface control is proposed and improved. Dynamic compressibility factor was used to accelerate the convergence of PSO, and the characteristic parameters were monitored to keep the PSO convergent. Moreover, intelligent integral of S surface control was introduced to eliminate steady-state errors.At the same time, a fuzzy neural network based on T-S model is proposed in this paper, which adopts mixed learning algorithms. The latter network automatically adjusts the operation rule to reduce the computation of the neural network and improve the robustness and adaptability of the control, so that the controller can work well ever when underwater vehicles work in rough ocean environment.Finally, the embedded control system for this mini AUV is introduced briefly.Its control architecture and information processes are presented including hardware and software.