| Air-cushion vehicle(ACV),as a special modern ship,has been well developed and applied in many areas especially in the m ilitary field because of its g ood seaworthiness characteristics and amphibians.ACV generate airflow through th e lift fans,which supply the air cham ber airflow through the apron passage,thus support the hull suspe nded in the water or on the ground to navigate by air cushion pressure,in order to reduce resistance and increase speed and impart ACV with high mobility.However,due to the unique navigation m echanism and air cushion properties,the dramatic changes in angle of heel which produced by coupled channel will easily lead to high-speed flicking when steering to change course at high sp eed,thus lead to seriou s skidding and even capsize.Im proper control of air pressure can easily lead to cou ntersink under interference of the environm ent perturbations,triggering a severe impact and operational failure.These instabilities of ACV increase the difficulty of manual operation,therefore the study of ACV posture is essential.A thought of decoupling control on ACV posture was put forward in this paper in order to ensure the stability and security of navigation.W e designed sail-heeling decoupling controller and heave-trim decoupling controller based on state feedback to control its navigation by establishing m odel of ACV move ment and m anipulation,validate the final design through simulation at last.Firstly,we established ACV motion-manipulate mathematical model of six DOF,as follows: fixed coordinate system and movement coordinates and the relationship of convert between the two;m odels of hyd rodynamic,air force,wave and each control surface.Integrated forces and moments generated by ea ch sub-model,build motion equations of six degrees of freedom in moved coordinates according kinematics and com plete the overall modeling in moved coordinates and validate the model through simulation experiments.Secondly,we designed a course-heeling decoup ling controller of ACV,as follows: present decoupling control m ethod based on the st ate feedback of the state space;sim plify heading-heeling motion model of ACV and deduce the correspondin g state-space m odel;design heading-heeling decoupling control algorithm based on st ate feedback and validate it through simulation experiments and introduce the classical PID control algorithm to control the course in the sim ulation experiments to compare with course-heeling decoupling control algorithm.Then,we establish the lifting system model of ACV as follows: use Bernoulli's principle to derive air pressure-flow relationship;bloc k modeling pressure-flow relationship of lifting fans and w ave pumping motion model and pre ssure-flow model of Apron gap;derive pressure-flow balance equation s of lifting system and adopt a m ultidimensional Newton method to solve it.Analysis and verify the correctness of the m odel through pressure simulation of each chamber and turbine fans.Finally,design a heave-pitch decoupling contro ller of ACV as follow s: simplify heavepitch motion model of ACV and deduce the co rresponding state-space model;design heavepitch decoupling control algori thm based on state feedback;in troduce the concept of heave stability and heave dam ping and validate the de coupling control effect of cham ber pressure and heave stability through simulation experiments. |
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