Application Research Of UUV Motion Control In Vertical Plane Based On Robust Control

Unmanned Underwater Vehicle (UUV) is a kind of small underwater self-propelled vector with high technology and can complete specific underwater tasks by remote control or autonomous operation. UUV can finish many tasks such as deep-ocean exploring, marine resource exploitation, wrecked ship salvage, port tactical reconnaissance in military and so on.The motion control technology is the foundation for UUV to complete many complicated tasks. Although the motion in vertical plane is a special case of UUV’s space motion, it is the key to finish some tasks. And the study on the control of UUV in vertical plane is very important both in theoretical and engineering practice.Though studying the method of Robust H∞ Control and UUV’s motion law in vertical plane and analyzing the problems of UUV’s depth and pitch, the paper tries to use the method of robust H∞ control to improve the robustness and stability of UUV’s motion control in vertical plane in marine environment.Firstly, the models of UUV’s motion in vertical plane and the actuator and ocean current disturbance are established.Secondly, considering the nonlinear of UUV’s motion and the uncertainty of its model and there exists parameter perturbation in fixed conditions,H∞ depth controller and pitch controller are designed based on H∞ robust control theory. Simulation results show that the control method can effectively control UUV’s depth and pitch in given speed interval and has strong robustness in fixed condition. At the same time, considering the situation that the actuators goes wrong and combining the fault-tolerant control theory,H∞ depth and pitch fault-tolerant controller is designed which can control depth and pitch effectively even if UUV actuator goes wrong.Thirdly, aiming at the characteristics of nonlinear and speed change of UUV’s motion,depth and pitch control model of UUV are established based on T-S model. The H∞ controller in vertical plane movement is designed applying the method of parallel distributed compensation (PDC) which has good effect on controlling the depth and pitch even if UUV is in the situation of speed change. And the simulation result shows that this control method has good dynamic performance in given speed interval.Finally, aiming at the problem of depth variance in UUV’s vertical plane, the methods of piecewise depth variance control and depth-pitch coordinated control are studied. And through a series of simulation, it indicates that the methods can effectively decrease pitch angle and increase the safety in the process of UUV’s submerging and inhibit the current disturbance.