Analysis And Design Of ADRC For Supercavitating Vehicle

When the vehicles move in the water with a high speed, because of the gasification of liquid, the phenomenon of cavitation occurs. At this time to match the reasonable design of cavitation, a large bubble will form on the surface of the body, which can almost wrap the entire vehicle. Because the vehicle is surrounded by cavity, the friction force of the vehicle is far less than the friction caused by the contact between the body and the surrounding fluid. So the speed of the vehicle is greatly improved, and this method has broken the limitation of low speed of traditional underwater vehicle. But the force of supercavitating vehicles in motion is very complicated because of the special navigation environment, so supercavitating vehicles pose technical challenges in control.First, in order to obtain the dynamic model of supercavitating vehicles, the coordinate systems are selected, transform relationships between the coordinate systems are reckoned and the stable operation operation scheme of vehicles are confirmed. According to the selected scheme we analysis of the various forces and moments that supercavitating vehicles has been subjected to, and analyze navigation vehicle dynamic characteristics through the appropriate coordinate system transformation. A nonlinear dynamic model of supercavitating vehicle has been established according to the related theorem. The longitudinal motion model of supercavitating vehicles has been obtained by the reasonable assumption and simplification.Because of the large external disturbance in the body, the vehicles’ model has the characteristics of nonlinear and multi-coupling, so ADRC controller is used to control the vehicle. The basic idea and principle of ADRC are described, and the structure and the function of each component are analyzed. The effect of the parameters in ADRC and their effects on the controller has been analyzed.As there are a lot of parameters in ADRC and it is difficult to adjust them,so an approach which adopting the Adaptive Genetic Algorithm(AGA) to optimize parameters of ADRC in order to adjusting its over-abundant parameters are proposed in this paper. The basic idea, basic factors, process and advantages and disadvantages of conventional genetic algorithm are introduced. Then, the adaptive genetic algorithm(AGA) based on the improved genetic algorithm is introduced, and the shortcomings of the algorithm are analyzed. In view of its disadvantages, this paper further improves the adaptive genetic algorithm, and applied it to the parameter adjustment of ADRC.Through simulation, the paper analyzes the dynamic characteristics of the open loop of supercavitating vehicles’ system, and the results show that the effectiveness of ADRC for the control of vehicles. As well as the advantages of the improved ADRC compared with the classical one. So that the improved ADRC has good control performance.