QFT Digital Controller for an Unmanned Research Vechile (URV)

Hamilton, Stuart; Horowitz, Isaac; Houpis, Constantine H.

doi:10.23919/acc.1989.4790599

Cited by 8 publications

(1 citation statement)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are several well documented aerospace applications, these include flight control systems of the ~.-1~~ aircraft (Betzold et al, 1984), the control of the forward svrept wing X-29 aircraft (Waike ei al, 1984), flight control reconfiguration design of the AFT1/F16 fighter ~~~rQ~vitz ~t al, 1985), MIMO flight control system design for YF16 aircraft (Miller, 1990), and application to a missile control system (Azvine and Wynne, 1992). There are also applications in the field of robotics and autonomous vehicles (Hamilton et al, 1989;Wang et al, 1988). The paper by Azvine and Wynne also includes the design of a QFT controller for a hydraulic positioning system.…”

Section: Applicationsmentioning

confidence: 97%

A review of quantitative feedback theory as a robust control system design technique

Azvine

Wynne

1992

Transactions of the Institute of Measurement and Control

View full text Add to dashboard Cite

Performance robustness has been an important issue in control and it has been increasingly recognised as an area of significance in many design applications. This issue has particular importance among the engineering community because it offers a solution to control system design problems for plant and processes that cannot be described by a single linear time-invariant model. The aim of this paper is to describe one of the methods available for robust control system design called Quantitative Feedback Theory (QFT) and discuss its application to engineering problems. QFT is a powerful design technique based on multi degree-of-freedom use of feedback. The basic building block of a multi-degree-offreedom system is a two-degree-of-freedom system in which two controllers are present, one inside the feedback loop, used to reduce closed-loop uncertainty, and the other prior to the loop, used to shape the input in order to achieve the required output. To show the power of the method, the application to an aero engine described by a non-linear model, linearised at five operating conditions, is discussed. A comparison of the QFT method is also made with the H-infinity method. It is shown that the H-infinity formulation of the QFT problem can produce a more conservative solution than the QFT method.

show abstract

Section: Applicationsmentioning

confidence: 97%

A review of quantitative feedback theory as a robust control system design technique

Azvine

Wynne

1992

Transactions of the Institute of Measurement and Control

View full text Add to dashboard Cite

show abstract

Survey of quantitative feedback theory (QFT)

Horowitz¹

2001

Intl J Robust & Nonlinear

200

164

View full text Add to dashboard Cite

SUMMARYQFT is an engineering design theory devoted to the practical design of feedback control systems. The foundation of QFT is that feedback is needed in control only when plant (P), parameter and/or disturbance (D) uncertainties (sets P"+P,, D"+D,) exceed the acceptable (A) system performance uncertainty (set A"+A,). The principal properties of QFT are as follows. (1) The amount of feedback needed is tuned to the (P, D, A) sets. If A &exceeds' (P, D), feedback is not needed at all. (2) The simplest modelling is used: (a) command, disturbance and sensor noise inputs, and (b) the available sensing points and the de"ned outputs. No special controllability test is needed in either linear or non-linear plants. It is inherent in the design procedure. There is no observability problem because uncertainty is included. The number of independent sensors determines the number of independent loop transmissions (¸G), the functions which provide the bene"ts of feedback. (3) The simplest mathematical tools have been found most useful*primarily frequency response. The uncertainties are expressed as sets in the complex plane. The need for the larger P, D sets to be squeezed into the smaller A set results in bounds on the¸G ( j ) in the complex plane. In the more complex systems a key problem is the division of the &feedback burden' among the available¸G ( j ). Point-by-point frequency synthesis tremendously simpli"es this problem. This is also true for highly uncertain non-linear and time-varying plants which are converted into rigorously equivalent linear time invariant plant sets and/or disturbance sets with respect to the acceptable output set A. Fixed point theory justi"es the equivalence. (4) Design trade-o!s are highly transparent in the frequency domain: between design complexity and cost of feedback (primarily bandwidth), sensor noise levels, plant saturation levels, number of sensors needed, relative sizes of P, A and cost of feedback. The designer sees the trade-o!s between these factors as he proceeds and can decide according to their relative importance in his particular situation.QFT design techniques with these properties have been developed step by step for: (i) highly uncertain linear time invariant (LTI) SISO single-and multiple-loop systems, MIMO single-loop matrix and multiple-loop matrix systems; and (ii) non-linear and time-varying SISO and MIMO plants, and to a more limited extent for plants with distributed control inputs and sensors. QFT has also been developed for single-and multiple-loop dithered non-linear (adaptive) systems with LTI plants, and for a special class (FORE) of non-linear compensation. New techniques have been found for handling non-minimum-phase (NMP) MIMO plants, plants with both zeros and poles in the right half-plane and LTI plants with incidental hard non-linearities such as saturation.

show abstract

Direct control design in sampled-data uncertain systems

Yaniv

Chait

1993

Automatica

View full text Add to dashboard Cite

QFT Digital Controller for an Unmanned Research Vechile (URV)

Cited by 8 publications

References 4 publications

A review of quantitative feedback theory as a robust control system design technique

A review of quantitative feedback theory as a robust control system design technique

Survey of quantitative feedback theory (QFT)

Direct control design in sampled-data uncertain systems

Contact Info

Product

Resources

About