Research On Safe Ride Control Strategy Based On ADRC For Air Cushion Vehicle

Air cushion vehicle (ACV) has been widely used in military and civilian fields, as atypical amphibious high performance ship. With the special navigation mechanism, ACV islifted from water (or ground), which makes its maneuverability significantly different fromconveantional surface ships. With little resistance between the surface and the hull, headingcan be easily changed under the environment disturbance. When ACV is turning, the hullheeling makes air leakage from one side, sometimes large heeling can induce large sideslipdangerously. When ACV is sailing on the water, the wave can cause the effusion area underthe skirt and cushion volume change periodically, cushion pressure and heave accelerationvary severely, so the seaworthiness of ACV is poor. Obviously ACV is difficult to control, itis necessary to study safety, efficiency, precise navigation control methods, therefore, thispaper studies the navigation control problem of ACV based on Active disturbance rejectioncontrol (ADRC).Firstly, a six-degree motion mathematical model of ACV is established. Hydrodynamicsand aerodynamics moel is obtained from the tank and tunnel experimental data. Consideringthe sucked air from the fan need to be accelerated to the same speed of ACV, the airmomentum force model is established. Cushion force model is set up based on the cushionsystem. By synthetizing the external force (torque) on each DOF, the motion mathematicalmodel of ACV is finished, it’s the foundation of the navigation control problem.Secondly, the theory of ADRC is well studied, which can achieve linearized dynamiccompensation and does not depend on the accurate mathematical model of the controlledobject. According to the theory of general state observer, the stability and error range ofextended state ovbserver (ESO) are analysised. In the design of tracking differentiator (TD),fsun()function is used to eliminate the flutter of system state. The stability of the nonlinearstate error feedback (NLSEF) control law is studied. The work above is the foundation for theimprovement of ADRC for the different navigation control assignment of ACV.Thirdly, the motion control method of ACV is studied based an ADRC. The heading andtrack guidance controllers of ACV are designed. Based on the theory of arrangement fortransitional process from ADRC, the coordinated control strategy of heading and turning isproposed, with method, ACV can achieve heading control under the safety turning rate, andthe sideslip angle is restricted in its safety boundary. To solve the problem that ACV issensitive to environment disturbance, its motion nonlinearity is obvious and its motion mathematical model of ACV is not so accurate, ADRC with control parameters self-tuningbased on support vector regression is proposed. With the adaptive ADRC, the control effectsof heading and track guidance are improved.Fourthly, heading-heeliing decoupling control of ACV is studied based on ADRC. In theheading control process of ACV, sometimes, large heeling can cause severe sidelipdangerously. To solve the problem above, ADRC decoupling control method is used, thedecoupling between heading control passage (The actuator is air rudders.) and heeling controlpassage (The actuator is nozzle.) is weakened. Dynamic surface ADRC is proposed, theNLSEF is replaced by dynamic surface control, then, the control efficiency ofheading-heeling decoupling control is improved and the high dependence on accurate systemmathematical model of Dynamic surface control is reduced.Finally, the static and motion characteristics, control method based on ADRC is studiedfor the cushion system. Under the basic assumptions, the nonlinear pressure-flow equations ofcushion system are established. With the mathematical mode of cushion system, the motioncharacteristics for the typical motion of ACV, the heave stability and damping (the heavelocation derivative and speed derivative) are studied. The control model of cushion system isestablished, ADRC is used to control the air into the fan to control the pressures of cushions.ESOs are used to estimate pressures of cushions and heave acceleration, NLSEF is designedwith compensation of heave acceleration. The method proposed effectively improves theseaworthiness and sailing stability of ACV.