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Landing control of unmanned aerial vehicles (UAVs) is challenging because of the strong nonlinear dynamics, multivariable, model uncertainties, wind variations, and sensor noise. Motivated by this fact, this paper investigates an automatic landing system (ALS) that includes trajectory generation and guidance law for the first flight test of a turbine-based combined cycle technology demonstrator. Specifically, the control scheme increases the original model's order to generate a reasonable monotone-decreasing throttle reference flare trajectory by the pseudospectral method. Subsequently, the guidance law based on innovative multivariable active disturbance rejection control is designed to robustly track the reference altitude and velocity simultaneously with high accuracy. The multivariable extended state observer (ESO) incorporated decoupling algorithm enhances the estimation capability and accuracy of potential problem in cross-coupling dynamics compared to the traditional ESO. It is proven that the closed-loop error dynamic has bounded-input bounded-output stability and an explicit upper bound is given. Numerical simulation verifies that the presented approach has better robustness and higher tracking accuracy for external disturbances and parametric uncertainties than the existing benchmark autolanding controller. Finally, flight tests show that the proposed ALS can land the vehicle effectively and safely under severe wind conditions. [ABSTRACT FROM AUTHOR]

Numerical simulation of an oblique detonation induced by a wedge is performed to investigate the formation and evolution of the oblique cellular detonation structure and the quantitative comparison of the cellular structure of a normal and an oblique detonation. The compressible reactive Euler equations are solved using the seventh-order WENO scheme on an adaptive mesh based on the open source program Adaptive Mesh Refinement in Object-oriented C++ (AMROC). The numerical results show that there are two sets of transverse waves, the left-running transverse waves (LRTW) and the right-running transverse waves (RRTW), which form the oblique cellular detonation structure. Although both sets of transverse waves are convected downstream, they propagate at almost the same relative velocity in the opposite direction. The LRTWs start in the transition zone because of the detonation instability. However, the RRTWs form due to the interaction between the deformed detonation front and the reflected shock wave from the wedge. For the same degree of overdrive, numerical simulations reveal that the characteristic cell size of an oblique detonation is almost the same as that of a normal detonation. [ABSTRACT FROM AUTHOR]