Research On Coordinated Control Allocation Of Rudders And Propellers Of Air Cushion Vehicle

The amphibious air cushion vehicle(ACV)is a kind of high performance ship,which is lifted from water surface or ground by the air cushion during the navigation.ACV has characteristics of high-speed and amphibiousness,so it is widely used in both the civilian fields and military fields.ACV has several special control surfaces,but the aerial propeller with duct and the aerial rudder are the main actuators for controlling the motion of ACV.The aerial rudder mainly provides the turning torque when the ACV is turning.However,the aerial propeller not only can provide the force to move forward,but also can provide the turning torque by adjusting the pitch angle of the left and right propellers.During the turning motion of ACV,when the speed is lower,then the efficiency of aerial rudder is lower,and the aerial rudder may not provide sufficient turning torque.This will lead to slower turning speed,longer rotation time and larger turning radius.So we need to use the pitch difference of the aerial propeller to turn auxiliarily,or even replace the aerial rudder.However,when the speed is higher,the efficiency of air rudder is higher,so only aerial rudder can be used to provide the turning torque that ACV need.But,due to the smaller lateral damping,and ACV is sensitive to the external environment disturbance.It is necessary to avoid using larger rudder angle to turn,so as not to cause serious sideslip even capsize.So,considering the safety and energy consumption,and the wear of actuator,it has practical significance to study the coordinated control allocation of aerial rudders and aerial propellers at different speeds in the heading control or course control of ACV.In this paper,a certain type ACV is taken as the research object.Based on the research of the course keeping control task of ACV,we further research the problem of coordinated control allocation of the aerial rudders and aerial propellers.Firstly,according to the idea of modular modeling,the experimental data of ACV and its parameters of the corresponding actuators,we establish the model of each module of the ACV.Then,the resultant forces and moments in the same direction of each module are added by superposition principle.Finally,the mathematical model of 4DOF motion of ACV is established.Secondly,in order to research the problem of coordinated control allocation of rudders and propellers of the ACV,we analyze and compare the performance and efficiency of aerial propellers and aerial rudders,and the effects of turning by each of them at different speeds.In this way,we can determine the coordinated use of aerial rudders and aerial propellers in different speed range.Then the coordinated control allocation model of rudders and propellers is established.And the coordinated control allocation problem of rudders and propellers is transformed into the optimization problem under the specified objective function and constrained conditions.Then,we use the improved standard particle swarm optimization(PSO)algorithm to solve the above problem.Finally,the control forces and moments are distributed reasonably.Then,for the problem of course control and safe navigation of the ACV,we propose the concept of course indirect control.The strategy is updating the desired heading by the sideslip angle.And then,we use nonsingular fast terminal sliding mode control algorithm to design the course controller and prove the stability.At the same time,in order to ensure the stability and safety during the navigation,we use Lyapunov nonlinear direct method to design speed controller.Then,we achieve the equal speed and course keeping control of the ACV.Finally,we apply the coordinated control allocation method of rudders and propellers to the equal speed and course keeping control task of the ACV.Then,we compare the simulation results with the simulation results that without coordinated allocation.The simulation results show the correctness,effectiveness and superiority of the proposed method in this paper.