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The sequential return difference method is applied to design a digital controller for a multivariable digital system. Although the open loop system is unstable it is shown that a controller which provides good transient behaviour and low interaction may be designed by the appropriate sequence of single-loop designs.

In this paper a method for designing dynamic compensators which reduce open loop interaction in a multivariable system is presented. An integral measure of interaction in the frequency domain is minimized to produce possibly dynamic compensators for either the system transfer function or its inverse. The technique is applicable to unstable systems, systems with time delays and, via a class of weighting functions can be used to obtain emphasised interaction reduction in particular frequency ranges. In addition, a feedback configuration aimed at lowering interaction is shown to give rise to a problem functionally equivalent to the above. An example designed interactively by computer is included to illustrate the effectiveness of the procedure.

This paper contains a survey of the computational methods which play an important role in the computer aided design in the frequency domain of single-input/single-output, linear systems, possibly including a pure time delay, and in continuous or discrete time. Emphasis throughout is on those numerical aspects unique to classical control systems design.

Shot processes may be used as models for a wide class of naturally occurring random processes ranging from non-Gaussian impulse processes to nearly Gaussian processes. This paper shows how shot processes with desired spectral properties may be simulated easily. Sev eral models are proposed for using shot processes as locally generated noise sources with statistical charac teristics which conform to many naturally occurring noise processes. More general models could be considered and the range of applicability can be extended beyond that men tioned in this paper. However, even the basic models treated can provide a much wider range of noise envi ronment than that usually considered in simulation tech niques.

This paper contains a survey of the computational methods which play an important role in the computer aided design in the frequency domain of single-input/single-output, linear systems, possibly including a pure time delay, and in continuous or discrete time. Emphasis throughout is on those numerical aspects unique to classical control systems design.

In this paper a method for designing dynamic compensators which reduce open loop interaction in a multivariable system is presented. An integral measure of interaction in the frequency domain is minimized to produce possibly dynamic compensators for either the system transfer function or its inverse. The technique is applicable to unstable systems, systems with time delays and, via a class of weighting functions can be used to obtain emphasised interaction reduction in particular frequency ranges. In addition, a feedback configuration aimed at lowering interaction is shown to give rise to a problem functionally equivalent to the above. An example designed interactively by computer is included to illustrate the effectiveness of the procedure.

The sequential return difference method is applied to the design of a digital controller for a multivariable digital system. Although the open loop system is unstable, it is shown that a controller which provides good transient behaviour and low interaction may be designed by the appropriate sequence of single-loop, digital, root-locus designs.

Pseudodecoupling enables the design of frequency-dependent precompensators (postcompensators) to improve the column (row) dominance of the compensated plant over an extended range of frequencies. This allows diagonal dominance to be achieved for a wider range of plants than was previously possible. The procedure arises from generalising Hawkins's pseudodiagonalisation procedure in a number of directions; in particular, stability of the compensator is guaranteed. Log σ plots are introduced as a means of determining the degree of dominance over a wide frequency range.

The state-space average model of a DC/DC convertor is used directly to obtain expressions for the ripple in any state or output of the model. This is used to rederive the current-ripple trade-off conditions in the Cuk convertor in a more straightforward fashion. In addition, it is shown that the buck convertor with input filter inductor and storage inductor coupling, and boost convertor with output filter inductor and storage inductor coupling, have similar ripple behaviour to the Cuk convertor at one port when the other port ripple is zero. For the case of equal input and output current ripples, the coupled inductor boost and buck are shown to be superior to the Cuk convertor.

A method is presented for calculating the transfer function corresponding to a state-space description so that the numerator and denominator of each element are relatively prime.