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From rigid automation to flexible autonomy
Published in Guy André Boy, Human–Systems Integration, 2020
Flying an aircraft is basically summarized in handling thrust and lift. When the pilot carefully trims pitch (i.e., adjusts downward lift of the horizontal tail) and flies hands-off, the aircraft flies straight for a while but then starts to cycle up and down in a slow mode: this is the phugoid phenomenon. Phugoid is a sinusoidal cycle that consists in putting nose down, gaining speed that causes increasing lift, aircraft starts climbing and loses speed, and so on.7 This is precisely what DHL crew of the Airbus A300 B4 did prior to land in Baghdad in 2003. In this example, flexibility is coming from collaborative problem solving combined with individual skills and knowledge of human operators involved.
Robust Adaptive Control Laws for a Winged Re-entry Vehicle
Published in IETE Journal of Research, 2022
Asha P. Nair, N. Selvaganesan, V. R. Lalithambika
The adaptive controllers described in the following sections control the rotational dynamics of the vehicle. The translational dynamics is being controlled by a guidance system. To do the control design, perturbation dynamics equations are taken around an operating (trim) point. Then the vehicle dynamics naturally decouples into longitudinal and lateral–directional modes. The longitudinal dynamics describe changes in forward, vertical and pitching motion of the vehicle. The longitudinal dynamics can be further decomposed into short-period and phugoid dynamics. The phugoid mode represents the dynamical interchange between the altitude and airspeed and is much slower than the short-period dynamics. Hence this can be neglected during the controller design. The short period describes the faster coupling between the vehicles’ angle of attack and the pitch rate. It can be written as where α is the angle of attack, V0 is the trimmed velocity, Zα is the force coefficient w.r.t α, Zq is the damping force, Zδe control force coefficient with respect to elevon deflection, Mα moment coefficient, Mq is the moment due to aerodynamic damping, and Mδe is the moment per degree deflection of the elevator. δe is the elevator deflection that provides the control moment.