Abstract: This report presents a methodology for adaptively assigning the closed loop poles of a linear multivariable system. The scheme is direct in nature in that no parametrized model of the unknown plant needs to be explicitely identified. Rather the control parameters, and an "equivalent" plant parameterization are simultaneously estimated from input-output data using linear parameter estimation procedures. Implementation of the scheme requires only knowledge of the system controllability indeces, and an upper bound on the observability index.

Abstract: A recent paper [1] has derived state space conditions under which the disturbance transfer function in a linear multivariable system can be zeroed by a dynamic compensator forced by a prescribed set of measurements. The present note derives necessary conditions for this problem in terms of the orders of the open-loop control, disturbance, and measurement transfer functions. These necessary conditions are shown to be generically sufficient for solvability. Moreover, they provide additional insight into the geometric solvability conditions, are simple to check, and extend the corresponding results obtained for the state feedback case [2].

Abstract: A transfer-function approach to linear time-varying discrete-time systems is developed in terms of skew (noncommutative) rings of polynomials and power series, both with coefficients in a ring of time functions. This framework is then applied to the study of uniform asymptotic stability and reachability. The problem of feedback control using dynamic state feedback is also considered.

Abstract: The steps involved in obtaining state-space realizations of a certain type of transfer function matrix over R (s, z) are illustrated. The dependence of the controllability and observability properties of the resulting delay-differential systems on the original transfer function matrix is investigated.

Abstract: The closed loop pole positions of a linear, multivariable system with unity rank output feedback are examined as a scalar feedback gain varies. In particular, consideration of the terminal locations of the poles as the gain increases indefinitely leads to a minor modification of a well known pole placement algorithm, resulting in a dyadic output feedback algorithm for zero assignment. This allows the designer to manipulate the root loci directly, and a consequence of the unity rank feedback is that the root loci of the multivariable system can be analysed in terms of a classical, scalar root locus diagram. The technique can be used to provide an improved ‘ point of departure ’ for the design of gain injecting compensators.

Abstract: A new technique for calculating the excess delay factor associated with the finite dominant pole approximation of the open-circuit voltage transfer function of trimmed uniform distributed RC networks is reported. This technique is based on Elmore's definition of the delay time which is associated with the transient response of the system. This response is then used to calculate a number of dominant poles and their associated delay factors. These are used to obtain the frequency and phase response of the network which is then compared with that obtained from a steady-state analysis.

Abstract: A transfer function including a not too `large? time delay is approximated with a transfer function characterised by only one stable, multiple pole. The approach is based on the Laguerre orthogonal function expansion of the impulse responses, corresponding to the given transfer function and the approximating one. The approach requires very limited computational effort to achieve a good approximation.

Abstract: A two-channel system defined by its transfer function G(S) is considered, and its controllability with the one of its input channels is examined after the introduction of a local output feedback with respect to the other channel (termed D-controllability). A criterion is given for D-controllability in terms of a (right) matrix fraction description G(S) = R(S)P−1 (S) of its transfer matrix G(S).

Abstract: Transformation from a transfer function matrix into a pulse transfer function is important for digital simulation and digital controller synthesis of continuous time systems. In this note a new simple numerical algorithm is proposed, which transforms a transfer function matrix directly into a pulse transfer function matrix without referring to state-space descriptions.

Abstract: Natural frequencies of transmission lines are identified by the poles obtained from line transfer function matrices. The procedure is based on an analysis in terms of the complex frequency s which has been introduced in the expressions of line parameters and transfer functions using the concept of complex depth.

Abstract: Some applications of microwave distributed-line networks have recently become known in the field of ultra high-speed (gigab its per second) digital communication systems as signal-processing or waveform-transformation networks. constant-resistance, two-strip, n-section coupled-line bridged-T networks constructed on thin-film substrates in aplanar-structure. An equivalent signal flow-chart is given for an n-section coupled-line which is part of the bridged-T network. This signal flow-chart shows that both numerator and denominator of the transfer function of the bridged-T network have real-coefficient rational functions of order n with respect to 2-1. However, depending on the choice of element values of the bridged-T network, we can obtain a non-recursive transfer function in which the denominator is constant, or a recursive transfer function i n which the numerator is constant. It is demonstrated that in this case all reflection coefficients for the backward-traveling power waves must be zero in the n-section coupled-line. AS a result, the bridged-T network ma? be used as a digital frequency multiplier, as a code converter lacking the characteristic wave distortion, or as a waveform equalizer to compensate pulse echo distortions.

Abstract: The issue of design of feedback controllers for elastic structures is addressed, where the objective is accurate and robust displacement control of the structure. Motivation for the work arises from study of control of multi-story buildings as part of the pseudo-dynamic-test method. If the force actuators have "fast" dynamics suitable control may be achieved by feedback of structural displacements and velocities, usilng a PID type controller logic. If the force actuators have "slow" dynamics it is suggested that structural accelerations also be fed back to the controller. Locations of the assigned closed loop poles are specified which guarantee robustness to variations in the actuator time constant and to uncertainties in the structural stiffness. Simplifying assumptions are made so that results are obtained using elementary arguments.