Showing papers on "MIMO published in 1986"

Linear-quadratic Gaussian with loop-transfer recovery methodology for the F-100 engine

Abstract: The design of a multivariable feedback control system for the F-100 turbofan jet engine is a challenging task for control engineers. This paper employs a linearized model of the F-100 engine to demonstrate the use of the newly developed linear-quadratic Gaussian with loop-transfer recovery design methodology that adopts an in- tegrated frequency and time-domain approach to multivariable feedback control synthesis so as to meet stability robustness, command following, and disturbance rejection specifications. ODERN turbofan jet engines represent an important multiple-input/multiple-output (MIMO) control ap- plication area since the dynamic coordination of fuel flow and several engine geometry variables can lead to improved performance and efficiency, while maintaining safe fan and compression stall margins. Indeed, the MIMO feedback con- trol of turbofan and turboshaft engine has received a great deal of attention in the past few years.1"8 The F-100 turbofan engine was used as a main design exam- ple for which different MIMO control methodologies were employed. The so-called linear-quadratic-regulator (LQR) ap- proach9'10 was the basis of engineering designs and evaluations1"4 that required the feedback of several F-100 state variables. In the past five years significant advances have been made in integrating time-domain optimization-based approaches (such as LQR and linear-quadratic Gaussian (LQG)) with fre- quency domain approaches. Such an integrated frequency- domain and state-space approach to MIMO control systems design was pioneered by Stein and his colleagues11"14 and has culminated to the so-called linear-quadratic Gaussian with loop-transfer recovery (LQG/LTR) methodology for MIMO feedback control synthesis. The primary objective of this paper is to illustrate the LQG/LTR design methodology using a four-input/fou r- output linear model of the F-100 engine. Specifically, we stress how MIMO command following and disturbance rejection performance specifications, as well as stability robustness specifications are naturally posed in the frequency domain us- ing the singular values of suitably defined loop-transfer matrices. Then, we demonstrate how the LQG/LTR design procedure is used to meet the posed specifications. Further-

The singular-G method for unstable non-minimum-phase plants

Abstract: In linear time-invariant feedback systems with plants which have both poles and zeros in the right half-plane, it is always possible to stabilize the system for a fixed plant. But in the previous optimum techniques, the stability margins might be so small as to render the design wholly impractical. This problem was overcome in the X-29 aircraft in a multiple-input-multiple-output (MIMO) setting, by use of a singular-G (compensation) matrix inside the loop. Excellent stability margins were then achievable over a wide plant parameter range, by means of a fixed-G compensation matrix. This paper extends the singular-G technique to the single-input-single-output (SISO) plant. The latter is converted into an equivalent N × N MIMO plant by means of N parallel independent time-varying modulators acting on the plant output, a technique previously used for non-linear network synthesis. The singular-G method is then applicable to the equivalent N × N MIMO plant. The detailed design procedure is presented by...

A systematic method for the stability analysis of multiple-output converters

Abstract: This paper deals with the dynamics of multiple-output DC-DC converters. A multi-input-multi-output (MIMO) feedback system model incorporating effects of the output fluctuation is derived for the converter. Based on system theoretic tools, a set of stability conditions is obtained for the MIMO model; the result is used to formulate a stable margin. A practical five-output converter was selected for illustration of the proposed analytic tool. Effects of the input filter and coupled inductor on system stability margin are investigated.

A design method of generalized root-loci for MIMO systems

Abstract: The classical root-loci techniques have been found to be unable to analyse and design MIMO systems. The multivariable root-loci methods developed in recent years, as only one parameter of the system can be adjusted at a time, are still difficult to meet the requirements of most practical systems. This paper first gives a definition of the generalized root-loci, from which all kinds of multivariable root-loci can be unified in such a framework. The authors then propose a design method of the generalized root-loci with multi-parameters. By this method, the advantages of classical root-loci method are preserved and yet the practical experiences of engineers are taken into account. Therefore the method is both convenient and efficient for designing MIMO systems. An explanatory example is included.

Adapted codes for communication through multipath channel

Abstract: Two systems for communication through multipath channels are presented and compared here. They are based on coding with binary sequences. The first one uses a pseudo-orthogonal coset code [1] and the second one the Yates-Holgate sequences [8,5]. Both are briefly described and their communication properties are recalled. An underwater experiment has been conducted with these codes. The obtained performances are given in terms of error and transmission rates. Two reception schemes are compared.

On the stability test for 2-D digital recursive filters

Abstract: It has been established that the stability testing of 2-D digital recursive filters can be reduced to two 1-D tests. The relationship between the stability of 2-D systems and passivity of corresponding 1-D MIMO systems is shown by calculating the resultant with appropriately partitioned matrices.

Identification algorithm for MIMO linear discrete systems with measurement noise

Abstract: A new algorithm for identifing MIMO linear discrete systems discribed by canonical form II is presented in this paper. Based on the one-way coupling characteristics of this form, the residual error method is used to identify the structure of the system, and the quasiextended least square method is proposed to estimate the parameters of the system. Computer simulation shows that this algorithms require less memory and computation time than others [1][2][3].

Complete system and signal identification of mimo closed loop systems in the frequency domain

Abstract: For linear time invariant MIMO closed loop systems a derivation of the correlation method in the frequency domain is given first. It is shown that in contrast to the indirect method and to the direct method the correlation method permits as well the determination of the unknown frequency response matrices of the plant and the regulator as the determination of the unknown spectral density matrices of the noise signals influencing the loop. This is denoted by the term "complete system- and signalidentification". Then for the indirect method, the direct method and the joint process method the solutions for the frequency response matrices and the spectral density matrices which can be determined from the measured signals only are summarized. Finally the interactive identification package IMSCLF containing the four different identification methods is described in a short manner.