An Investigation of the Impedance of a Powered Flying Control System

Abstract

This thesis describes an investigation to determine the impedance of a powered flying control system. The first stage of this project investigated the impedance of a hydraulic servomechanism in a rigid environment. The impedance was predicted theoretically and measured experimentally by sinusoidal and random excitation of the output end and also by sinusoidal excitation of the valve input. has been shown to exist between the theoretical prediction sand the experimental results. Following the determination of the impedance of the servomechanism in a rigid environment, the analysis and experimental work was extended to include the: effect of a flexibility connected to the output end of the servomechanism. It was demonstrated theoretically and verified experimentally that the impedance of this system may be predicted by combining the impedance of the servomechanism with the impedance of the flexibility using the normal laws of impedances addition. The impedance of the servomechanism has also been determined with its anchorage connected to a flexibility. The theoretical analysis of this system produced - result of some complexity, but it has been show that as the frequency of excitation tends to zero and also to infinity, the system impedance can be readily predicted and these predictions hove been verified experimentally. The most recent stage of the project has been to investigate the effect upon the servomechanism of connecting the servo valve input to a flexibility. The analysis of such a system was found to be difficult and the resulting predictions unreliable. The experimental results did not agree with the theoretical predictions for this system, indicating that the effect of valve input flexibility must be obtained experimentally.