Showing papers on "Control theory published in 1970"

The Megawatt-Frequency Control Problem: A New Approach Via Optimal Control Theory

Abstract: This paper records the development of a state variable model of the megawatt-frequency control problem of multiarea electric energy systems. The model is in a mathematical form necessary for application of theorems of modem optimal control theory.

Suboptimal control of linear time-invariant systems subject to control structure constraints

Abstract: A method is presented for designing controllers for linear time-invariant systems whose states are not all available or accessible for measurement and where the structure of the controller is constrained to be a linear time-invariant combination of the measurable states of the system. Two types of structure constraints are considered: 1) each control channel is constrained to be a linear, time-invariant combination of one set of measurable states; 2) each control channel is constrained to he a linear, time-invariant combination of different sets of measurable states. The control system, subject to these constraints is selected such that the resulting closed-loop system performs as "near" to some known optimal system as is possible, i.e., suboptimal. The nearness of the optimal system to the suboptimal system is defined in two ways and thus, two types of suboptimal controllers are found.

Application of an Optimal Control Theory to a Power System

Abstract: In recent years important research has been done in the area of system optimization by control engineers. Many theoretical results have been published but application examples have mainly been on low-order systems. An attempt is made to apply a certain class of optimal control theory, known as the state regulator problem, to obtain an optimal controller to improve the dynamic response of a power system. The system differential equations are written in the first-order state variable form. A cost functional is then chosen, and the matrix Riccati equation is solved. Puri's and Gruver's method is applied for the numerical computation, and the system is made initially stable by shifting the system eigenvalues.

Differential games, dynamic optimization, and generalized control theory

Abstract: In this paper, we examine the problem of control in a generalized framework in which there are more than one criterion, more than one intelligent controller, each of which has access to different information. It is argued that optimal control, differential games, dynamic team theory, etc., can all be viewed as special cases of this generalized control theory. Useful concepts and potential difficulties are discussed.

Control theory and physiological feedback mechanisms

Abstract: Control theory and physiological feedback mechanisms , Control theory and physiological feedback mechanisms , کتابخانه مرکزی دانشگاه علوم پزشکی ایران

Tuning controllers for set point changes.

Abstract: : Optimum settings for disturbance changes are not optimum for changes in set point; and in certain applications set point changes are rather common It is the purpose of this article to develop controller tuning relationships based on the minimization of error integrals for set point changes It will also be shown how these relationships may be used to tune both conventional and direct digital control loops (Author)

An approach to adaptive control using real time identification

Abstract: An adaptive controller consisting of a real time identifier and a minimum variance regulator is discussed. The identification is done by augmenting the state with the unknown parameters of the process. This usually leads to a non-linear filtering problem. By choosing a model of special structure the problem can, however, be reduced to a linear problem. The control law is derived using stochastic optimal control theory. By choosing a special criterion, the stochastic control problem can be solved analytically. The behaviour of the adaptive controller is illustrated in two examples.

On the Flow Capacity of Automated Highways

Abstract: Virtually all proposed systems for highway automation have at least one mode in common—steady-state car following. The nature of this mode is extremely important, as it can determine the upper limit of flow capacity of an automated highway. This limit is explored for a linear headway controller, and a fundamental relation between the effective vehicle response time and the permissible traffic stream density is obtained. The required intervehicular spacing with a linear headway controller is shown to be proportional to the effective vehicle time constant for small-signal inputs; thus, one can achieve small spacings and high flow rates by reducing this parameter to 1 sec or less. However, the vehicle is then highly responsive to small changes in lead-vehicle speed—possibly resulting in both passenger discomfort and poor fuel economy. These shortcomings can be avoided by using a linear velocity controller for automatic car following.

On the linear servomechanism problem

Abstract: This paper considers the problem of the optimal control of a linear servomechanism using output feedback. It is shown that a generalization of the standard optimal control problem can be obtained in such a manner that optimal control is possible by feeding system outputs into a dynamic controller which operates only on past and present values of these outputs. This represents a new approach to the design of controllers for linear systems which may play an important role in applications of optimal control theory. It allows the linear servomechanism problem to be treated, for the first time, in a realistic manner.

Design of gas-turbine controller using inverse Nyquist method

Abstract: Following a brief outline of the inverse Nyquist design method as applied to multivariable systems, its application is illustrated by a detailed analysis of the stages involved in the design of a controller for a gas turbine. This leads to a new type of controller which may be regarded as a multivariable version of a classical lead compensator. Comparison with more familiar multivariable design methods shows the inverse Nyquist method to be superior, not only in the controllers it leads to, but also in the information it gives the designer.

Use of control words to change configuration and operating mode of a data communication system

Abstract: A data communication system comprising a processor, a memory, a communications controller and a plurality of terminal devices utilizes control words to select the configuration and to select the operating mode of the communication system. This system uses peripheral control words stored in memory to select the number of bits in message characters which may be used in the data communication system, to select the baud rate of the message which is received and to select a synchronous or asynchronous mode of transmission.

Commutative controller: a new technique for the design of multivariable control systems

Abstract: If a linear time-invariant multiple-input multiple-output plant is represented by a square transfer-function matrix G(s), a spectral analysis may be carried out to determine a set of system characteristic transfer functions. A multivariable feedback controller may then be synthetised by first designing a set of single-loop controllers for these characteristic systems, and then transforming the results to obtain the required multivariable controller.

Dual side arm controller

Abstract: A dual side arm controller for use within the armrests of a seat. The seat is made up of a back portion and a pair of retractable armrests. The side arm controller is made up of a handgrip, cables and torque tube. The relationship between these elements allow for the retractable movement of either of the armrests without substantially affecting the operation of the side arm controllers.

Specific optimal control of the linear regulator using a dynamical controller based on the minimal-order Luenberger observer†

Abstract: The problem is considered of designing the optimal, fixed configuration, dynamical feedback controller of order (n—m) required to control an nth-order linear system with output of order m(m

Optimal stochastic control of nonlinear systems

Abstract: An algorithm is proposed for the feedback control of nonlinear systems, the observations of which are corrupted with noise of unknown statistics. The feedback loop contains a nonlinear Kalman filter, which produces sequential least-square estimates of the state of the system, and a controller designed to minimize an instantaneous performance criterion based on the state estimates. The scheme requires the on-line integration of n(n + 3)/2 differential equations, where n is the number of unknown states and parameters. The scheme is applied to the feedback control of a CSTR with a first-order exothermic reaction the temperature measurements of which are corrupted with random noise.

Floating-type electronic servo-motor process controller

Abstract: A floating-type electronic process controller including a differential amplifier which compares a voltage proportional to a process variable with a set point voltage to produce a deviation signal whose polarity and magnitude reflect the direction and extent of the departure of the process variable from the set point. The deviation signal is converted into on-off signals by applying it to a pair of comparator channels to which are also applied a triangular reference voltage having a constant frequency. When the deviation signal reflects a process variable which is below the set point, one channel is activated to yield square-wave pulses whose rate corresponds to the frequency of the reference voltage and whose pulse duration is proportional to the magnitude of the deviation signal, but when the deviation signal reflects a process variable which is above the set point, the other channel is activated to provide similar square-wave pulses. The square-wave pulses serve to trigger the triac control circuit of a reversible motor operatively coupled to a final control element, the pulses from one channel causing the motor to turn in one direction and the pulses from the other channel causing the motor to turn in the other direction, the duty cycle of the motor being determined by the duration of the pulses.

Authority Role of a Functional Manager: The Controller.

Abstract: In this study of the controller's decision-making authority, controllers, their peers, and superiors in 25 firms were interviewed for their perceptions of the controller's authority in specific decisions. The data indicate that controllers do not have the same authority in all their functions or in the various decisions within those functions. Also controllers, their peers, and superiors have different perceptions of the controller's authority. A comparison is made with the findings of an earlier study on personnel managers, and some implications are noted.

An Application of Control Theory Methods to the Optimization of Structures Having Dynamic or Aeroelastic Constraints.

Abstract: Optimal control models for design of structures with weights minimized by constraints involving fixed eigenvalues

Modern control theory and optimal drug regimens. II: Combination therapy

Abstract: In this article we show how well-known concepts from control theory are directly applicable to the problem of determining methods for administering a combination of drugs to achieve a desired level for the equivalent amount of any one of the drugs under consideration. The problem of drug administration is shown to be equivalent to a discrete-time optimal control problem. Methods for solving the discrete optimal control problem via dynamic programming are shown.