Research On Lateral Attitude Under-actuated Control Technology Of Hypersonic Vehicle

In this dissertation,the casecade control technology of lateral is studied,based on the hypersonic vehicle with the characteristics of only aileron in the stage of pure aero-dynamical control and unstabilitily of Dutch roll mode during the reentry.The basic state of the aircraft is redefined,and laternal linearized motion equation is given.Based on that,the lateral object characteristics are analyzed.And the analysis results show that the aircraft has large roll-to-sideslip ratio,which lais the foundation for the design of roll control strategy.Research on realizing the goals of controlling the roll angle and reducing the sideslip angle with only the two ailerons,this dissertation proposes a cascaded lateral underactuation control strategy.Based on the lateral kinematics equation,the underactuated control mechanism is expounded.The lateral control structure is divided into the inner loop of the sideslip angle and the outer loop of the roll angle,based on the cascade control idea of the aileron controls the sideslip and the sideslip angle controls the roll angle.And then,the sideslip angle of output of external loop is limited,meanwhile,the control strategy and corresponding parameters are designed.The results show that this strategy implements the roll angle control,guaranteeing the sideslip within the safe range casued by the roll angle,and has strong robustness.For the problem that the value of the sideslip angle is difficult to be measured exactly during the entry process of hypersonic vehicle,this dissertation analyzes the mechanism of lateral stabilization by lateral load and proposes a lateral underactuation control strategy based on lateral overload.The simulation results show that the strategy can solve the problem of the slip angle difficult to be measured exactly.Due to the problem of the sideslip angle difficult to be measured when presence of wind interference,uses observer idea,this dissertation designs the rolling angle outer loop controller to estimate the disturbance of wind based on the extended state observer and feedforward compensation for system.The inner loop use inertial sideslip angle feedback control,and the given the lateral underactuation control strategy based on the extended state observer.The simulation results show that this strategy can solve the control problem of the wind disturbance caused by the sideslip angle can not be measured exactly,and improves the control performance of the system.