Lateral Control Law Design Of Reentry For Hypersonic Vehicle

The reentry and return of the hypersonic vehicle includes three phases which are reentry,terminal area energy management and automatic landing. As a critical flight phase, reentry proposeshigh requirements to attitude control, and lateral control is the difficulty of the attitude control. Thuslateral control problems of reentry are researched in this paper.First of all, the six-freedom-degree mathematic model of the hypersonic vehicle is built, and thelateral object characteristic is analyzed in detail. The lateral object characteristic analysis includesstatic stability analysis, modal analysis and departure characteristic analysis which is focused on.Secondly, according to the problem that the efficiency of aero surfaces is too low or limited inthe early reentry, lateral RCS control strategy and control law parameter of the phase is designed,during which RCS control was used solely and composite control of RCS and aero surfaces was used.Due to the discrete operating characteristic, RCS control law is designed in linear system, and thencontinuous torque command by the control law is transformed into discrete torque command by usingthe PWM algorithm.Thirdly, according to the phenomenon such as the dutch roll instability and roll reverse in theearly reentry, unconventional lateral aerodynamic control strategy called “the rudder controls rollangle,the aileron arguments the dutch roll.” is designed, which is based on analysis of the reason thatconventional lateral aerodynamic control strategy isn’t applicable to the sample hypersonic vehicle.According to the problem that kinematic coupling of hypersonic vehicle is serious and largeangle of sideslip is prone to appear in the process of the large roll maneuver at the largeangle-of-attack, anti-sideslip feedforward control strategy based on control compensation andanti-sideslip feedback control strategy based on the rate of change of angle of sideslip is designed, andthen engineering application method of anti-sideslip feedback control strategy is proposed.Finally, nonlinear simulation environment of reentry based on Matlab is built, and themonte-carlo method is used to assess the lateral control law. The results show that the lateral controllaw of reentry can satisfy the requirement for control and the control robustness is strong.