Investigation of a Discrete C-Star Transient Response Controller for the YF-16at a Selected Flight Condition.

摘要

The feasibility of a discrete digital flight controller for the YF-16 Lightweight Fighter Prototype aircraft at Mach .8 at sea level is investigated. The investigation is limited to the longitudinal pitch axis. A reduced state, short period mathematical model of the YF-16 is developed from available data. The open loop stability and response characteristics of the model are shown to be unacceptable, necessitating the use of closed loop compensation. The minimization of a discrete cost function is used to develop a recursive discrete control formula. The thesis discusses and incorporates the concept of a proposed C-Star handling qualities criterion in the determination of acceptable response. Digital computer simulation on a CDC 6600 computer for various sample rates using a zero order hold or first order hold control scheme, results in a stabilized system model whose output falls within the bounds of a defined C-Star envelope, and capable of performing the tracking task of following a 1-G climb pilot input command. Typical results in the form of plotted time history information are discussed. Also discussed are the effects on the system of variations in sample rate, and cost functional penalty parameters. Control weighting is shown to be inversely proportional to the natural frequency while the trajectory weighting determines the damping ratio.