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Dissertation
Control of aircraft operating under adverse conditions
Doctor of Philosophy (Ph.D.), Drexel University
Jun 2012
DOI:
https://doi.org/10.17918/etd-3812
Abstract
Almost all aircraft in use today rely on some form of automatic control system to remain safely aloft. Though control under nominal conditions is a mature field, control methods are less developed for airborne vehicles operating beyond their nominal flight envelopes. Adversities like loss-of-control and upset conditions affect all variations of aircraft and are thus of great concern. Two flying vehicles operating under different adverse conditions are explored in this study: a spinning gun-launched projectile and a transport aircraft. It is shown that similar closed-loop output-tracking regulation and H2 control methods can be employed to safely control each respective system under dangerous circumstances. For the first vehicle, a control scheme is proposed that can compensate for the confiing angle of a gun launched projectile and allow front-mounted canards to efficiently change the projectile flight path without reaching an aerodynamic stall condition. The problem is formulated as a tracking control problem where the reference signal is a sinusoidal input of non-zero bias. The sinusoidal component directly compensates for the body precession, while the non-zero bias imparts a trajectory-altering control action. This approach enables the canard actuator angles to be efficiently regulated with respect to the vehicle's heading direction to minimize drag and prevent aerodynamic stall. For the second vehicle, a civil transport jet actuator jam failure scenario is explored utilizing the NASA AirSTAR Generic Transport Model (GTM). A control algorithm is developed to mitigate the actuator jam using a reconfigurable output-tracking regulator. The regulator is developed using a servomechanism formulation where the failed control surface is modeled as an exogenous input to the degraded plant. The approach exploits a set of linear controllers selectively enabled using switching control and outer-loop compensators to optimally track a desired reference input with the remaining available control surfaces and control authority. This approach addresses the loss-of-control authority over the failed control surface in addition to the persistent disturbance input that arises from the jammed control surface.
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Details
- Title
- Control of aircraft operating under adverse conditions
- Creators
- Mishah Uzziél Salman - DU
- Contributors
- Bor-Chin Chang (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Mechanical Engineering (and Mechanics) [Historical]; Drexel University
- Other Identifier
- 3812; 991014631957304721