Modeling,Analysis And Control Of Active Heave Compensation System For Underwater Detection Sonar

Underwater detection sonar realizes the detection of underwater targets by transmitting and receiving ultrasonic signals with certain characteristics,and is currently one of the mainstream technical methods for underwater detection.Underwater detection sonar needs to be deployed from a carrier to underwater for target detection,and its carrier will generate a large heave motion under the influence of wind,waves and currents,causing the underwater detection sonar to shift in the heave direction.The angle of the ultrasonic echo signal is changed,which causes a large deviation between the detection results and the actual data,and seriously reduce the performance of the sonar.Therefore,the operating efficiency of sonar equipment is effectively improved by equipping the sonar carrier with an effective heave compensation system,which is of great significance in practical applications.In this paper,an active heave compensation system based on servo motor drive technology is designed from an underwater detection sonar project.The active heave compensation system is modeled and a control strategy is designed,the correctness of the model was verified.Then an error model of the heave compensation system is established.According to the model,the influence of the error sources of the heave compensation system on the compensation accuracy are comprehensively analyzed.The compensation accuracy is verified in theory.Finally,experiments results show the effectiveness of the proposed heave compensation system and the reasonableness of the error analysis.Details of this research are as summarized follows:Firstly,the components and the main principle of the proposed heave compensation system are presented,the scheme of active heave compensation system based on servo motor drive technology is designed.The mathematical model of each system component is established.According to the proposed scheme,the trajectory tracking loop controller and the velocity loop controller are designed with the idea of double closed loop compound control to realize the heave compensation with a feedforward compensation controller based on the structural invariance principle.Meanwhile,to overcome the problem of large inertia and time delays,considering the nonlinear and non-stationary characteristics in actual ship motion,a ship motion prediction algorithm based on the Empirical Mode Decomposition Auto Regressive model is used to forecast the ship motion online.Thus,the complete mathematical model of the proposed heave compensation system is established.The effectiveness of the model and the tracking ability of the control scheme are verified with the comparison between the sine response of the model and the experimental data collected from the established experimental system.Secondly,in order to verify compensation accuracy of the system,the kinetic equation and the proposed heave compensation system are used to analyze the influence of the factors which cause compensation error(e.g.,measuring element,hydrodynamics,friction,etc.).The error source models of the heave compensation system are built,which are verified by the simulation.Then,an error model of the heave compensation system is established according to the superposition principle.With this model,the total error of the heave compensation system under different heave value can be calculated.The results show that the compensation accuracy of the heave compensation system meets the design requirements.Finally,a human-computer interaction interface and lower-level computer control software are developed for the experimental platform for the heave compensation system.The theoretical contribution of the paper is verified by experiment.The feasibility of the control strategy is verified by experimental results.Meanwhile,the heave compensation device meets all the design requirements,which is correspond to the error analysis.It demonstrates the correctness of the error model based on the error analysis.