Showing papers on "Variable structure control published in 1974"

Bang-Bang Excitation Control

Abstract: This paper concerns itself with the time-optimal control of large oscillations in power systems by bang-bang excitation control. The determination of the instants at which the control is switched from one level to another and the application of such a piece-wise constant control to a tenth order nonlinear model which includes the effects due to field time lag and damper bars and the dynamics of exciter and govternor are the principal aspects of the paper. The results show that as compared to the normal proportional voltage regulator the bang-bang control effects more efficient damping of the system. Significant improvements are seen in the rate of response and the number and amplitudes of oscillations. The enhancement of the critical clearing time due to bang-bang network control is inidicated. It is hoped that the approach to the bang-bang control outlined in this paper would serve as a guide to future system studies on discontinuous control.

Optimal periodic control of lumped parameter systems

Abstract: Some subsidiary conditions for determining the superiority of the periodic control to the steady control are derived The necessary condition for the optimality of period is established by adding a new condition to the well-known condition which can yield merely the stationary value of the objective function Some considerations are also given for a system having a single state variable and a single control variable and for the linear control problem, which very often appears in many practical cases

Control regulating several control variables - each variable independently adjustable using current control circuits

Abstract: Each control distance has assigned to it a current control circuit on which a control loop for a set control variable is superimposed. A decoupling network is used to transfer the control deviation occurring on a current control circuit to the input of other current control circuits. A switching arrangement can be provided for extra attenuation of the current control circuits. A servo control can be provided to enable a set nominal control value to be input at the same time as an additional nominal current value into all underlying current control circuits. The damping effect caused by the regulating controls is not increased.

Nonlinear systems equivalent to controllable bilinear systems

Abstract: Given a nonlinear analytic control system with an equilibrium point sufficient conditions are given for the existence of a one-to-one transformation to coordinates in which the system becomes bilinear, and an explicit construction is given

A note on the inverse optimal control of nonlinear systems

Abstract: A procedure for the selection of a nonlinear feedback law has been suggested by Thau as a part of his study on the inverse optimal control problem of nonlinear systems In this note we suggest an alternative feedback law which turns out to be better, in the sense that the transient response improved and at the same time the control energy requirement is reduced

Optimal angular velocity control with finite terminal time for an asymmetric spacecraft

Abstract: A method is presented to obtain optimal feedback control laws to reduce the angular momentum of a tumbling asymmetric spacecraft to rest within a finite interval of time. This correspondence only treats the case with unconstrained but finite continuous control functions.

Optimal control of neutral systems

Abstract: This correspondence considers the necessary conditions for optimal control of a nonlinear neutral system with general cost function. Using variational techniques, it is shown that the adjoint variable is discontinuous, and furthermore, the form of the discontinuity is characterized.