The Precise Model Of Parachute And Unity3D Simulation In Mars EDL

Parachute descent is one of the most crucial phase during the whole process of Mars exploration,which determines the success or failure of the exploration mission.So it is important to analyze and evaluate the parachute descent.In allusion to the difficulties encountered during the parachute descent,this thesis researches the problem of accurate modeling about the detector–parachute system.Then,based on the accurate model,the whole EDL process(Entry,Descent and Landing)which includes parachute descent can be showed,using the Unity3 D software in the virtual environment.The main contents and results in this dissertation are summarized as follows:Firstly,a more accurate model of the Martian atmosphere is established in parachute descent.Meanwhile,the exact condition of parachute deployment is also confirmed,including the height,the velocity,the Maher number of parachute.Both of the work provides the conditions for the analysis of the later Mars exploration process.Secondly,the added mass force of the object moving in the unsteady fluid is analyzed and calculated.As a special case,the added mass force of detector–parachute system is analyzed when the parachute is decelerating in the Martian atmosphere.The analysis provides a basis for the establishment of accurate model during parachute descent.Thirdly,the parachute opening process of parachute descent phase is discussed.The added mass of parachute is represented by the rotating ellipsoid method during parachute inflation,then the precise parachute opening model is established and the parachute force(opening force)is calculated.In addition,the thesis using the parachute of MSL(Mars Science Laboratory)detector simulated and verified the parachute opening model.Then,the added mass of detector–parachute system is obtained in the steady descent process of the parachute descent,and a 6DOF mathematical model of detector–parachute system is established.The change of system's attitude,position and velocity with time is obtained through the model,and the simulation verifies and demonstrates the accuracy of the model.Meanwhile,the influence of the lateral wind on the parachute and the stability of the parachute after disturbed are analyzed,and the parameters of the parachute is determined to guarantee the stability.The simulation results show that the parachute used by MSL detector has a certain stability.Finally,the simulation platform of the whole EDL process is designed.The guidance algorithm in entry and power descent phase as well as the established accurate model of detector–parachute system during parachute descent phase are imported into Unity3 D,the whole real time animation of EDL process is demonstrated in the software platform at last.Therefore,the Mars EDL process can be directly and vividly displayed to people using the software platform.