Transactions of the Institute of Measurement and Control

McLean, D.

doi: 10.1177/014233128700900401pmid: N/A

Cowling, David A.

doi: 10.1177/014233128700900402pmid: N/A

The problem of designing a control system for a nonlinear unstable canard aircraft is presented. Design performance criteria including robustness and pilot-handling qualities are discussed. The eigenstructure-assignment technique is used to determine the gains of a simple, practical system. The results of three designs are presented and show good handling and robustness qualities.

Ali, Q.R.

doi: 10.1177/014233128700900403pmid: N/A

Aircraft having flexibility can develop large amplitude acceleration due to structural modes, in addition to that caused by the rigid body motion. Reduction of these loads by means of active control systems is an important problem in flight control. Load alleviation control by means of full state variable feedback, obtained as a solution to an eigen vectorleigen value assignment problem is demonstrated in this paper. The mathematical model of the aircraft used as an example, the C-5A, includes the linearised longitudinal equations of the rigid motion, the dynamics associated with the first flexural mode of the wing and the linear dynamics of the control surface actuators. Assessment of the degree of alleviation achieved is based on the calculated root mean square (RMS) values of both the bending and torsional moments at the wing root, these moments being represented by an output equation which is a linear combination of the state variables of the aircraft dynamics and the command signals to the control surface actuators,

Hutt, G.R.

doi: 10.1177/014233128700900404pmid: N/A

The determination of the aerodynamic pitch stability derivatives of a hypersonic-flight vehicle require the measurement and subsequent analysis of model motion time histories. This paper outlines, briefly, the strain-gauge and optical systems employed with captive and free-flight model experiments as performed in a hypersonic wind tunnel. The advantages of optical model position measurement are presented, highlighting both an intensity modulating system and an intensity compensated absolute position sensing system.

Cook, M.V.

doi: 10.1177/014233128700900405pmid: N/A

An experimental facility for the dynamic investigation of the stability and control characteristics of small scale model aircraft in a wind tunnel is described. Some typical results for a conventional and unconventional aircraft configuration are presented.

James, K.A.; James, R.W.

doi: 10.1177/014233128700900406pmid: N/A

An investigation into the behaviour of a thermostatic expansion valve used to control the refrigerant flow into an evaporator was undertaken using a thermodynamically based mathematical model. The emphasis of the paper is on the behaviour of its sensor, which is a remote bulb charged with a refrigerant liquid/vapour mixture. The model was used to test the influence of simplifying assumptions and to determine the simplest model that could be an adequate representation of the TEV. Possible applications for the simplified models are discussed.

Grimble, M.J.

doi: 10.1177/014233128700900407pmid: N/A

A polynomial matrix solution of the optimal deterministic servomechanism problem, for continuo its-time systems, is presented. A closed-loop optimal controller is obtained driven by the tracking error, as in classical control schemes. The controller is easily computed via a standard polynomial matrix manipulation and solution algorithms.

Thomas, E.

doi: 10.1177/014233128700900408pmid: N/A

The results of earlier experiments suggest that a linear relationship exists between the optical signal passing through liquids in the refractive index range 1.3 to 1.6 when the liquid couples two multi-mode optical fibre cables, An analogue transmission system has been constructed, with a solid state camera and a computer as the basis of the detector system, in order to examine in detail the emission from the receiver optical fibre cable. The measurements obtained and the empirical equations deduced from them, suggest the possibility of an intrinsically safe technique for monitoring the refractive index of liquids that are non-absorbent in the red region of the optical spectrum.

Coates, R.

doi: 10.1177/014233128700900409pmid: N/A

The admittance circle diagram is an important method of characterising the terminal response and, thus, the electrical equivalent circuit of acoustic transducers. Equipment to yield such plots is relatively costly and consequently less readily available than might be desired. This paper describes a method of obtaining admittance plots, typically to frequencies of the order of a few megahertz, which involves only modest circuit development. The method avoids circuit design complexity by relying upon the computing power of any readily available microcomputer to effect correction of parameter cross-coupling.