The Study On Predictive Control Of An Object's Level On A Ship In Random Ocean Waves

The ship often is sailed and fought in the wind wave . With the disturbance of random wave the ship will inevitably roll and result in the ship's incline, especially, for small ships which the most obliquity of the ship is likely to reach above degree 15.In the actual combat the rolling movement of the ship will result in difficult control of the artillery for the artillerymen on the ship, reduce the artillery's probability of shots, and affect the power of the artilleryBy direct control of the object (artillery) fixed on the ship it can be kept horizontal state all the time. As a result, it can improve the controlling quality of artillery and increase its probability of shots. This paper brings up a predictive control system that makes the object keep horizontal state on the sailing ship in random wave. On the basis of cybernetics through forecast roll and pitch of a ship and by adjusting the object's space position and keep its horizontal state without limit of actual sea state according to the control rules with the predictive value of ship's roll angle and pitch angle.This paper applies ITTC single-parameter ocean wave spectrum to simulate a random long-crested ocean wave according to statistics superposition theory and real-time simulate disturbance on the ship by random wave. It simulates roll and pitch of the ship in random wave in the time domain and gains roll angle (t) and pitch angle (t) signal of ship rolling movement.For the dynamic process of ship rolling movement, this paper analyses its dynamic date with time series analysis method and brings up this system's the most excellent Autoregressive model (AR model) according to least AIC criterion (Akaile , information criterion).It reveals the regular pattern of ship rolling movement and forecasts the future value of roll angle and pitch angle, then transforms it to adjusting value of object and adjusting it according to appropriate control rules.The AR model can comparatively well forecast the movement trend of actual ship's rolling. Through this predictive control system controlling and adjusting the artillery (or other objectthat requires keeping horizontal state) can make it keep about horizontal state all the time and make artillerymen easily control the artillery and consumedly increase the probability of shots in the actual combat. This system is a exploration in the field of real-time intellectual control of object on the ship, its control process is simple and convenient ,and it has a high applied value.