Mars Entry Flight Simulation And Guidance Research

Mars environment is complicated and changeable, and the entry process is important to Mars exploration mission. The poor knowledge of vehicle’s statuses in entry phase can lead to huge difference between actual situation and the desired, even the failure of whole mission. Using current entry technology, only easily landing sites are choosed due to their low elevation and thick atmosphere. The major focus of this dissertation is flight simulation and dynamic characteristics of vehicles’ entering the Mars atmosphere. The entry guidance methods are also studied in the dissertation. In addition, a software is designed for Mars entry simulation. The main work is summarized as follows:The dynamic characteristics of ballistic and lift entry trajectories are respectively studied. The angular motion of a rotational vehicle in atmospheric entry is studied, and the necessary condition and the sufficiency condition are obtained. In addition, the characteristics are analysed from the sensibility of trajectory parameters to entry conditions and the performance of flight entry under initial deviation and external disturbance. Thus the features of entry motion under different conditions and the scatter properties of trajetories under disturbances are achieved. By optimizing calculation, the corridor and related constraint conditions of the lift entry trajectory are achieved.The predictor-corrector guidance and nominal trajectory guidance are respectively studied. Based on the relationship between bank angle and range, the longitudial and lateral guidanc are sepetated. The amplitude of the bank angle is calculated through longitudial guiadance and the sign is decided by lateral guidance. Based on Numerical Predictor-Corrector Guidance method and Sliding Mode Control theory, two kinds of longitudial guidance are designed. The proposed trajectory planning algorithm is based on the Gauss Pseudospectral Optimization Method. The cross range is held in the dead band boundary relative to itself using the proposed lateral guidance.In conclusion, some researches have been done in dynamics characteristics and entry guidance of Mars entry vehicles. The simulation models, calculation methods, analytic results and research conclusions can offer references for future Mars exploration missions.A software for Mars entry simulation is developped. To realise functions of simulating the vehicle’s entering atmosphere, mathematical models are formulated and a trajectory optimization algorithm based on Gauss Pseudospectral Method is developed. Following the functional requirement, the software is diveded into different modules. These modules help the software doing nominal and off-nominal simulations. The software is tested in different realistic scenarios.