This is a second edition of this well known textbook. It is well structured, beginning with longitudinal and then lateral aircraft dynamics and autopilots. Useful presentations of the frequency responses of aircraft are provided, and numerical examples of transfer functions are given. The book provides a very good source of material on autopilots although modern active control manoeuvre demand systems are not included. Missile control systems are logically split into chapters on autopilots and guidance. Proportional navigation and command guidance are described although Kalman filtering techniques are not dealt with. An excellent new chapter describing the integration and analysis of an integrated flight and fire control system for the FIS has been included in the new edition. New chapters are included in the edition on several topics. Multivariate decoupled control of flight motions is described, but modern approaches to stability margin analysis and robust multivariate design are not included. A chapter on structural flexibilities is provided and deals with missile examples. Structural mode interaction in aircraft and the resulting limitations on the performance of active control manoeuvre demand systems are not dealt with. An interesting chapter on pilot modelling has also been added, although recent work on pilot handling qualities specifications is not discussed. The book should be useful to all those working in the field of aircraft or missile guidance and control. It will be particularly appreciated by those who have prior knowledge of control systems and some experience in dealing with the equations of motion and descriptions of aircraft aerodynamics. The autopilot and missile system examples are particularly valuable. Dr D. A. COWLING, CEng, MRAeS Nondestructive Testing Techniques Edited by D. E. Bray and D. McBride

Automatic Control of Aircraft and Missiles — Second edition, J. H. Blakelock John Wiley & Sons, Baffins Lane, Chichester, PO19 IUD. 1991. 646pp. Illustrated. £59.

The objective of the thesis is to study the possibility of using input-output feedback linearization techniques for controlling nonlinear nonminimum-phase systems. Two methods are developed. The first one is based on an approximate input-output feedback linearization, where a part of the internal dynamics is neglected, while the second method focuses on the stabilization of the internal dynamics. The inverse of a nonminimum-phase system being unstable, standard input-output feedback linearization is not effective to control such systems. In this work, a control scheme is developed, based on an approximate input-output feedback linearization method, where the observability normal form is used in conjunction with input-output feedback linearization. The system is feedback linearized upon neglecting a part of the system dynamics, with the neglected part being considered as a perturbation. Stability analysis is provided based on the vanishing perturbation theory. However, this approximate input-output feedback linearization is only effective for very small values of the perturbation. In the general case, the internal dynamics cannot be crushed and need to be stabilized. On the other hand, predictive control is an effective approach for tackling problems with nonlinear dynamics, especially when analytical computation of the control law is difficult. Therefore, a cascade-control scheme that combines input-output feedback linearization and predictive control is proposed. Therein, inputoutput feedback linearization forms the inner loop that compensates the nonlinearities in the input-output behavior, and predictive control forms the outer loop that is used to stabilize the internal dynamics. With this scheme, predictive control is implemented at a re-optimization rate determined by the internal dynamics rather than the system dynamics, which is particularly advantageous when internal dynamics are slower than the input-output behavior of the controlled system. Exponential stability of the cascade-control scheme is provided using singular perturbation theory. Finally, both the approximate input-output feedback linearization and the cascade-control scheme are implemented successfully, on a polar pendulum 'pendubot' that is available at the Laboratoire d'Automatique of EPFL. The pendubot exhibits all the properties that suit the control methodologies mentioned above. From the approximate input-output feedback linearization point of view, the pendubot is a nonlinear system, not input-state feedback linearizable. Also, the pendubot is nonminimum phase, which prevents the use of standard input-output feedback linearization. From the cascade control point of view, although the pendubot has fast dynamics, the input-output feedback linearization separates the input-output system behavior from the internal dynamics, thus leading to a two-time-scale systems: fast input-output behavior, which is controlled using a linear controller, and slow reduced internal dynamics, which are stabilized using model predictive control. Therefore, the cascade-control scheme is effective, and model predictive control can be implemented at a low frequency compared to the input-output behavior.

On the use of input-output feedback linearization techniques for the control of nonminimum-phase systems

In this work an analysis of the application of the Quantitative Feedback Theory (QFT) technique to different marine systems is presented. Specifically, the problems of dynamic positioning of a moored platform, stabilization of a fast ferry and the tracking control of a hovercraft are studied. This control problem presents interesting questions to deal with, since the plants are non-linear, multivariable, underactuated and subject to large disturbances due to waves.Three multivariable nonlinear problems are solved using different sequential procedures. It is shown that the QFT controllers synthesis achieve robust performance, decoupling, environment disturbance reduction, quick answers and tracking precision. Therefore, it is shown that robust techniques based on QFT methodologies result feasible and very suitable, constituting an attractive alternative for robust design of marine vehicles.

https://polipapers.upv.es/index.php/RIAI/article/download/9592/9533

Aplicación de técnicas de control robusto QFT a sistemas navales

A modern fighter aircraft is exposed to very different flight conditions and must despite that perform infallibly in every single situation. Several variables like center of gravity, speed, altitud ...

/pdf/styrlagsdesign-for-ett-instabilt-stridsflygplan-med-hjalp-av-38wjoo6uop.pdf

Styrlagsdesign för ett instabilt stridsflygplan med hjälp av QFT

Variations of the quantitative feedback technique (QFT) are applied to a multi-input-multi-output (MIMO) flight control problem with unstable, nonminimum phase plants. The authors present specialized techniques that enable the designer to achieve acceptable results for effective plants which are both unstable and non-minimum phase. The weighting matrix function is discussed, and a method of developing frequency dependent compensation is presented. The longitudinal control system, defined as a single-input-single-output (SISO) system, is designed using the loop transmission function. The limitations imposed by right-half-plane poles and zeros are discussed as the design is presented. A straightforward approach to designing a prefilter is also presented. Singular-G and optimal blending methods are used to improve the achievable stability characteristics of the lateral-directional (MIMO) effective plant. A brief discussion of the design of prefilters for a MIMO system is included. >

R.N. Paschalle

Papers

Applying variations of the quantitative feedback technique (QFT) to unstable, non-minimum phase aircraft dynamics models