Research On Track Tracking Safety Control Method Of Air Cushion Vehicle

Air cushion vehicle(ACV)is a special ship,which is amphibious,and can navigate in places where conventional surface ships cannot navigate,such as ice,swamp,beach,grassland and so on.As one of the main functions of motion control of the ACV,path-following has potential safety hazards such as easy stall,sideslip and high-speed tail flick compared with conventional surface ships.Therefore,it is necessary to study the path-following safety control method of the ACV.In this paper,the safety control methods are mainly studied in two aspects:external uncertain interference,drift angle and yaw rate constraints in the path-following process of the ACV.The main research work is as follows:1.Aiming at the problem of external uncertain interference in the process of path-following,an interference estimation algorithm and guidance algorithm are designed,and a path-following controller based on the guidance algorithm and interference estimation algorithm is further proposed.Firstly,in order to make the ACV track the given desired path,the SFLOS guidance algorithm is designed.Aiming at the uncertainty of external disturbance,an extended state observer is designed to estimate and compensate the external disturbance.Then,the track angle controller is designed to make the actual track angle of the ACV track the expected track angle;The longitudinal speed controller is designed to make the actual longitudinal speed track the desired longitudinal speed of the ACV.Finally,the simulation results show that the path-following controller based on extended state observer has higher tracking accuracy than the path-following controller without extended state observer.2.Aiming at the safety risks of stall and rollover caused by excessive drift angle and yaw rate in the path-following process of the ACV,a control method based on constant constraints of drift angle and yaw rate is designed.Firstly,the constraint on the drift angle is transformed into the constraint on the longitudinal speed,and then the longitudinal speed is constrained by LBLF,so as to ensure that the drift angle is within the safety limit of the drift angle.Then,it is assumed that the virtual yaw rate meets a certain range,and LBLF is used to restrict the yaw rate,so as to ensure that the yaw rate is within the safety limit of the yaw rate.Finally,the simulation verifies that the drift angle and yaw rate can be constrained within their respective safety limits by using LBLF.3.Aiming at the problem of coupling the rate of gyration constraint and speed,the time-varying rate of gyration constraint is obtained based on the ACV simulation platform and the motion mathematical model of the ACV,and a time-varying yaw rate constraint path-following controller based on IBLF is designed.Firstly,for the problem that the safety limit of the yaw rate is a constant value,based on the ACV simulation platform and combined with the motion mathematical model of the ACV,the time-varying yaw rate constraint closer to the actual navigation state of the ACV is obtained.Then,in view of the problem that the virtual yaw rate must be assumed to meet a certain range when LBLF is used to restrict the yaw rate,IBLF is used to restrict the rotation rate directly,so there is no need to consider that the virtual yaw rate meets certain assumptions,which can better reflect the strictness of the constraint.Finally,the simulation results show that the yaw rate can also be constrained within the safety limit of time-varying yaw rate by using IBLF.