Longitudinal Motion Attitude Forecasting And Control Of A Craft

In the state of high speed, hydrofoil will be affected by the influence of various interference from the external environment, such as wind, wave and other random interference factors.These interference factors can produce disturbance of force and torque from different directions on hydrofoil, affecting the normal and smooth sailing for the hydrofoil. Some measures must be taken to control in order to make sure the hydrofoil maintain to be steady.The control system installed on the hull of hydrofoils produce control and torqueto reduce the impact of external forces and motions acted on the ship movement.And to produce an effective control,it is necessary to design a controller for hydrofoil control system.Taking the backstepping commonly being used to solve the nonlinear systems problem into account, this paper basing on hydrofoils longitudinal motion of nonlinear mathematical model , take attitude stabilization as target and design a controller for hydrofoil longitudinal motion attitude based on the idea ofbackstepping. The control requirement is to make heave displacement and pitch angle can be stabilized within a smaller error range in a limit time in the condition of a given desired attitude.On this basis, in order to solve the interference and uncertainties existed in the actual sailing for hydrofoils, this paper design the adaptive sliding mode controller based on backstepping to control the longitudinal movement attitude of the hydrofoil. To verify the results of the controller, do the simulation by using the matlab and get the result.By respectively compare three kinds of situation that adding sliding mode controller based on backstepping, no controller and the desired attitude to get the result of the controller.For the further study on hydrofoil longitudinal attitude and considering the situation that the generalized dynamic fuzzy neural network has the advantage of fast learning, parameters and structures of neural network being dynamically adjusted and so on, this paper choose the generalized dynamic fuzzy neural network as the method to forecast the hydrofoil longitudinal attitude.Then get the results of backstepping controller in the situation of certain interference by simulation and analyse the result, Concluding that the designed controller based on backstepping can effectively control the hydrofoil heave displacement and pitch angle. And adaptive sliding mode controller based on backstepping can effectively counteract the effects of interference, hydrofoils heave displacement and pitching angle being significantly improved after adding the controller. Compared with the situation of no controller, the maximum of longitudinal attitude respectively decreased by 76% and 90%. The maximum relative error of longitudinal attitude using generalized dynamic fuzzy neural network to forecast was less than 26%. we can conclude that the selected prediction method is effective.