Abstract

The goal of the research is to optimize a full-state feedback controller for a Boeing 707-120 pitch control using differently tuned Linear Quadratic Regulators (LQRs) to optimize four conflicting objectives (pitch recovery dynamics, elevator effort, reaction time, and comfort). The step response of the aircraft’s pitch is primarily simulated in MATLAB/Simulink. The aircraft's condition is set at cruising altitude and is preparing for descent by pitching down 10 degrees, with only a short period of pitch oscillation considered. The aircraft's longitudinal dynamics are obtained and modelled under certain assumptions, with elevator deflection as the input. The desired pitch dynamics of the aircraft are determined by a short-period thumbprint chart, where a pole placement is implemented and simulated by assigning the desired eigenvalues from a “satisfactory” region of the short-period thumbprint chart. Later, an LQR controller is implemented and simulated by tuning matrices Q and R in various ways. By normalizing and comparing the step response of the LQR controller with pole placement, it is demonstrated that LQR can optimize conflicting objectives with minimal elevator effort, thereby optimizing multiple conflicting objectives while extending the lifespan of elevators. This research contributes to SDG 9 by advancing innovation in aerospace control technology and supporting the development of resilient and efficient aviation systems infrastructure.

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