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Introduction
Published in Arthur G.O. Mutambara, Decentralized Estimation and Control for Multisensor Systems, 2019
The Shuttle Upper Atmosphere Mass Spectrometer (SUMS) experiment is for obtaining measurements of free-stream density during atmospheric entry in the hypersonic, rarefied flow regime. These measurements, combined with acceleration measurements from the companion high-resolution accelerometer package experiment, allow calculation of orbiter aerodynamic coefficients in the flow regime previously inaccessible using experimental and analytic techniques. The High Resolution Accelerometer Package (HRAP) experiment uses an orthogonal, triaxial set of sensitive linear accelerometers to take accurate measurements of low-level (down to micro-gs) aerodynamic accelerations along the orbiter’s principal axes during initial re-entry into the atmosphere, that is, in the rarefied flow regime.
Novel smooth sliding mode attitude control design for constrained re-entry vehicle based on disturbance observer
Published in International Journal of Systems Science, 2019
Fang Wang, Changchun Hua, Qun Zong
Since RLV behaves the advantage in dramatically reducing the cost of accessing space and has the promising application in military situations, it has been achieved more and more attention in recent years. During the flight mission, it follows a predefined trajectory towards the designated landing point, travelling from space to the dense atmosphere of earth and it induces high levels of uncertainty and variations in key flight parameters. A primary requirement for re-entry guidance and flight control law is that they exhibit sufficient level of robustness to allow close tracking of the pre-defined trajectory despite high levels of uncertainty and disturbances (Mathavaraj, Halbe, & Padhi, 2010). Besides, flight control design is very challenging because aircraft dynamics changes dramatically when altitude and Mach number vary from atmospheric entry at hypersonic speed to subsonic approach and landing (Shtessel & Krupp, 1997). It should be pointed out that input constraint must be considered for the hypersonic vehicle (HSV) since control system is in open loop state under the occurrence of input saturation, and HSV may lose stability or even disintegrate if output of the actuator does not return to the linear work space. The unavoidable constraint on control input renders the control systems design of HSV an even harder endeavour except the aforementioned challenge (Serrani, Zinnecker, Fiorentini, Michael, & David, 2009).