Predictive Control And Simulation For Path Following Of Astronautic Survey Ship

Astronautic survey ship is an ocean going TT&C (track, telemetry&control) station, whose task is the same to land TT&C station. But surveyship has its particularity, it is to capture and track the target in the conditionsof location changing, water flowing, hull vibration and antenna shaking. Theocean going survey ship moves in six degrees of freedom under disturbancesinduced by wave, wind and ocean-current. The change of course causes theantenna beam deviation from the target, and even causes the loss of target. Inorder to avoid the antenna blocked, the ship needs to travel along apredefined path while maintaining a certain course. The path followingcontrol system of ship is a typical nonlinear control system which hascharacters such as under-actuated, strong nonlinear, susceptible to varyingparameters and environmental disturbances. The study of the subject iscontributive to study the general nonlinear system control problem and hasgreat significance in academic study. It will benefit the maritime security anddesign of a new generation of TT&C ship. The application of predictivecontrolalgorithm in path following ofship is investigated.Firstly, Mathematical models of path following system for ship areestablished. Modeling plays a key role in Controller design. Based on thereview on modeling method of path following, the equations of ship motionand maneuvering characteristics are acquired, and the platform of dSPACEHILS real-time simulation is introduced. Secondly, the method of model linearization is investigated to linearizethe nonlinear model of path following for ship. Considering TT&C of singlearc segment, a discrete state-space linear model based model predictivecontroller is devised. The SIMULINK experimental results indicate that themodelpredictive controlin path following is feasible.Thirdly, considering TT&C of short arc segment and multi circles, twomulti-model predictive control algorithms based on sway displacement areinvestigated. One improves soften reference trajectory. The other improvesswitching guidelines. The experimental result indicates that it could realizevalid wide range path following controlof sway displacement.