Showing papers on "Control theory published in 1974"

Application of fuzzy algorithms for control of simple dynamic plant

Abstract: The paper describes a scheme in which a fuzzy algorithm is used to control plant, in this case, a laboratory-built steam engine. The algorithm is implemented as an interpreter of a set of rules expressed as fuzzy conditional statements. This implementation on a digital computer is used online, to control the plant. The merit of such a controller is discussed in the light of the results obtained.

Model reference adaptive control with an augmented error signal

Abstract: It is shown how globally stable model reference adaptive control systems may be designed when one has access to only the plant's input and output signals Controllers for single input-single output, nonlinear, nonautonomous plants are developed based on Lyapunov's direct method and the Meyer-Kalman-Yacubovich lemma Derivatives of the plant output are not required, but are replaced by filtered derivative signals An augmented error signal replaces the error normally used, which is defined as the difference between the model and plant outputs However, global stability is assured in the sense that the normally used error signal approaches zero asymptotically

Generalized Techniques of Harmonic Elimination and Voltage Control in Thyristor Inverters: Part II --- Voltage Control Techniques

Abstract: Theoretical techniques of voltage control for the half-bridge and full-bridge inverters are derived based on the results in [1]. Detailed analytical results for the symmetrical pulsewidth modulation method of voltage control are also presented. Voltage control techniques are derived whereby harmonic elimination is possible in variable-frequency variable-voltage three-phase inverter circuits. The technique for the half-bridge inverter is optimized subject to the constraint of switching frequency of the SCR's, using the concepts of modern control theory. Variable-frequency variable-voltage sinusoidal output in three-phase inverters is possible by employing the techniques developed. The methods show great promise in application to variable-speed ac motor drive systems.

Computer-Aided Control System Design

Abstract: Computer-aided control system design , Computer-aided control system design , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Stable Adaptive Schemes for System Identification and Control - Part II

Abstract: The extension of some of the results contained in Part I [1] to the case when only the plant outputs rather than all its state variables are accessible for measurement is discussed. A unified approach to the synthesis of an adaptive observer is presented whereby the plant state and parameters are simultaneously estimated. Uniform asymptotic stability of the scheme is proved using Lyapunov's direct method. The information provided by the adaptive observer is used to synthesize an adaptive controller for the plant. While all the principal results obtained here are for the case of a single-input single-output plant, extensions to special classes of multivariable systems is indicated.

Synthesis of Multivariable Regulators: The Internal Model Principle*

Abstract: For the multivariable control system described by\(\dot x = Ax + Bu,y = Cx,z = Dx\) (wherey is the measured output andz the output to be regulated) conditions are given for the existence of a controller which preserves output regulation and loop stability, in the presence of small parameter variations in controller and plant. Under mild conditions, such a “strong” synthesis is shown to exist if and only if the regulator problem with internal stability (RPIS) is well-posed. Synthesis is achieved by means of a feedback configuration which in general incorporates an invariant, and suitably redundant, copy of the dynamic model adopted for the exogenous disturbance and reference signals which the system is required to process.

Status of periodic optimization of dynamical systems

Abstract: The problem of the periodic optimization of dynamical systems, recently considered to some extent in the literature, is reviewed here. The most interesting results among those available are illustrated. Mention is made of the most significant and open aspects of the problem.

Linear-quadratic-gaussian control with one-step-delay sharing pattern

Abstract: The optimal control of discrete-time, linear-quadratic-Gaussian systems with one-step-delay sharing information pattern is considered. The optimal controller is shown to obey a certain "separation" property. Furthermore explicit discrete-time equations are derived whose solutions are the gains of the optimal controller.

Automatic electric battery charging apparatus

Abstract: A controller for incorporation in a battery charger to limit the overall length of the charge, and also to provide short topping-up charges at intervals after the main charge has been completed, if the battery is left connected to the charger. The controller allows the limit on the length of the charge to be set to either 10 or 141/2 hours; the subsequent topping-up charges then start at intervals for 10 or 141/2 hours, and last for about 40 or about 55 minutes, depending on the setting of the main charge time limit. The controller is illustrated in conjunction with a charger control circuit which terminates the main charge when the rate of rise of battery voltage falls below a predetermined value, and this is normally expected to occur before 10 (or 141/2) hours have elapsed, leaving the time limit set by the controller as a safeguard.

Control system for a stored program multiprocessor computer

Abstract: A stored program electronic digital computer has a control system for the computer. There are a plurality of processes in the computer. There are four stored program controllers in the computer which operate in different processors within the computer system. There is a master controller, a command controller, a task controller, and a disc I/O controller. These four controllers operate in a hierarchy of control. Each controller exercises control over a given level of work in the computing system.

A Fast-Response DC Motor Speed Control System

Abstract: This paper describes the design, construction, and testing of a thyristorized speed control unit for a separately excited dc motor. The motor is fed from a three-phase six-pulse fully controlled thyristor bridge. A speed loop with a proportional plus integral controller maintains the desired speed irrespective of the load variations on the motor. An inner current control loop protects the thyristors from overcurrents. This loop also provides fast response overcoming the effect of disturbances such as variations in supply voltage. The design aspects of the control loops are discussed, and experimental results are given.

Pulse width modulation control for valves

Abstract: A control circuit for a fluid controller such as a solenoid driven valve. A pulse output system operating at a fixed or variable frequency, with pulse width varying as a function of error signal. An integrator for integrating the error signal and providing an input to a threshold trigger circuit, and a multivibrator for periodically grounding the integrator output.

Closed-Loop Positioning of Hemiplegic Patient's Joint by Means of Functional Electrical Stimulation

Abstract: We report about the results on positioning of the ankle joint of a hemiplegic patient and of normal experimental subjects, using functional electrical stimulation (FES) of antagonistic muscle groups and position feedback. Such a controller is intended to be used as the execution level of a multilevel orthotic system. The synthesis of the controller has been made with the aid of the components of an analog hybrid computer. Experimental results show that the static and dynamic properties of regulated movements are not essentially inferior to the properties of voluntary movements. There are stated technological problems that will have to be solved before the controller can be clinically applied for rehabilitation purposes. At the present state of the art, the poor technology of FES, the unsolved problem of fatigue with FES muscles, size, price, and bad cosmetic effect prevent the position controller from being clinically applicable.

Physically Realizable Wide Power Range Optimal Controllers for Power Systems

Abstract: A physically realizable linear optimal controller in terms of easily measurable state variables for the stabilization of power system is developed in this paper. The controller is based on a fairly accurate fifth order synchronous machine and a first order voltage regulator. The transformation of the system equations into a cannonical form enables us to determine the weighting matrices Q and R of the quadratic cost function with simple procedure and to design an optimal controller which can stabilize a power system under widel. power range operating conditions. Transient response test on the nonlinear model proves the effectiveness of the linear control design.

Direct current motor speed control apparatus

Abstract: A direct current motor speed control system is disclosed including a motor armature current controller operative in conjunction with a speed controller and a current reference ramp function generator, such that an effective clamp is provided on the current reference rate of change in the motor speeed control operation in relation to providing less amplification of the noise frequency portion of the motor speed actual feedback signal supplied to the speed controller.

Robust solutions to linear multivariable control problems

Abstract: In this paper a special case of the Regulator Problem with Internal Stability (RPIS) [1] is studied from the standpoint of obtaining solutions that are insensitive to perturbations in both the system parameters and the controller gains. The ability to include "robustness" into the problem yields new insight into the role played by dynamic compensation in linear control system synthesis.

On-line modification of computer programs

Abstract: A programmable data processor or controller serving as the main control in a control system contains an executive program for controlling the transfer of information between the processor and system equipment, updating that information during on-line control of the equipment and modifying the executive program to change operating parameters of the system while the data processor is controlling the system equipment. Modification of the executive program and displaying of system parameters related to the executive program and the system equipment is accomplished through the use of an operator's console which communicates with the data processor and system equipment as a result of operator intervention.

Brake controller and short circuit probe disconnect

Abstract: A control for brakes in trailer vehicles comprising a circuit providing pulsed signals to the brakes. It is preferred that the time or width of each pulse is equal but the frequency of brake pulsing is increased in accord with inertially sensed stress. The frequency of the signal is directly related to the movement of a dampened cantilever beam which normally blocks the passage of light to a light sensitive target or monitor but wherein the passage of light increases and is attenuated by the beam as the beam moves, under inertial imbalance, to permit added light to be sensed. In addition, the control circuit, vulnerable to short circuits in the vehicle circuit from control element to brakes, is continuously monitored by a disconnect element which senses the existence of the short circuit and accomplishes a disabling of current through the control circuit at a threshold to avoid injury to the control circuit. An electromagnetic coil surrounding a reed switch accomplishes the circuit disconnect in a manner timed by a capacitance in the reed switch line. The probe disconnect timed pulse acts on an indicator visible, audible or tactile to the user of such controls and this intermittent signal indicates the presence of a short circuit requiring correction before the normal operation of the control system can be restored.

Interprocessor communication apparatus for a data processing system

Abstract: In a data processing system having independently operating asynchronous processors, apparatus is disclosed which provides for interprocessor synchronization and/or information exchange. Synchronization interlocks and controls are provided for both identifying shared resources of a control processor and an input/output controller (IOC) processor and for obtaining control over these shared resources. If a conflict situation for any one of the shared resources arises, apparatus is disclosed whereby the IOC processor is provided the capability of assuming control over the shared resource even though the central processor has control over it. One of the shared resources is an interprocessor communication register which allows communication of control information between both the central processor and the IOC processor and from the central processor to the peripheral processor over a shared bus.

Secondary storage facility for data processing

Abstract: A controller for use in a data processing system for coupling a direct access storage element to the system. The controller contains a control path for routing control information from the system to various circuits in the controller and designated storage elements to enable a transfer of data stored on the medium over a data path in the controller. The controller data path also couples the medium to the system and includes a switching network which permits the data to be selectively coupled to or from one of two separate system buses. Control information routed to the controller identifies the system to be involved in a transfer and routing circuits in the controller provide the connection between the controller and designated systems.

Hamilton-Jacobi theory for periodic control problems

Abstract: The general problem of periodic optimization is considered in this paper. The contribution consists in stating sufficient conditions for the optimality of a control satisfying the periodicity constraint. The result has been achieved by means of the classical Hamilton-Jacobi equation, suitably modified in order to consider the peculiar constraint of the problem. Finally, an interesting application of the theory to the case of linear, time-invariant systems is given.

Large systems

Abstract: It is argued that we need theories of large systems. This is particularly so since society is composed of large systems, and since without applicat.ions, control theory will be sterile. Some typical large systems are economics, education, urban systems, transportation, energy, and the environment. Observe that these systems are not independent. This makes the associated problems more interesting and difficult. It is noted that the fuzzy set theory of Lotfi Zadeh appears promising in this area since all of the concepts associated with large systems are imprecise or fuzzy.

Drive for connection to multiple controllers in a digital data secondary storage facility

Abstract: A secondary storage facility for a data processing system including a drive unit which connects to a pair of controllers. Switching circuits in the drive unit couple a data transfer section and a common control section for the transfer section to one or the other controller in response to selection signals. Other control sections connect to respective ones of the controllers to receive signals and a selection circuit responds by transmitting the selection signals. If one controller tries to transfer information to or from the common control section while the selection signal designates the other controller, the transfer does not occur. If the attempted transfer is to the common control section or from predetermined locations in the common control section, the attempt is retained so the drive can signal back through the other controller when the selection signal can change. If the attempted transfer is from the common control section, then the drive transmits back to the controller a unique code.

Robust controllers for linear regulators

Abstract: This paper presents a formulation and solution of a problem in the design of robust controllers. These controllers are realizations of solutions to control problems which remain solutions in the case of arbitrary perturbations in the problem data and the controller parameters. For the particular problem studied here, it is shown that arbitrary perturbations are admissible only in the feedback gains and perturbations in the problem data (system parameters) must be suitably restricted in order for there to exist robust solutions.

Traffic control system

Abstract: A traffic control system which controls the timing of a plurality of traffic lights at a plurality of intersections with a variety of timing patterns, this invention contemplates utilizing modules which will operate automatically to control the flow of traffic and which also is readily controlled by a master controller for changing traffic flow cycles. The controller which is placed at the intersection is preset or programmed to establish a basic timing cycle. This timing cycle can be changed by the transmission of signals from a master controller and the storage of the signals at the intersection. A single master controller can thereby control a plurality of intersection controllers to vary the traffic flow over a wide area. By using multiplexing techniques, a single pair of signal wires can connect the master and a large number of independent intersection controllers. The individual controllers are designed to accept a plurality of standard plug-in components which are interconnected by a single component. Each of the standard components provides a choice of such things as basic timing cycles by the simple procedure of external switch plugs which can be changed simply, with few tools, in suit. In this manner, once the system is installed, changes in the traffic flow can be compensated by simple changes in the intersection controllers.

Power system excitation and governor design using optimal control theory

Abstract: Integrated excitation and/or governor control systems are the result of using novel approaches for the selection of stabilizing signals in electric power systems. Such controllers have usually been derived on the basis of a linearized system model, an attractive practical feature of these being that a linear, time-invariant optimal controller may be derived. The power system is non-linear, however, and it is for this non-linear system that an optimal controller is ideally required. Previous work in the area is shown to be deficient in the light of this requirement and subsequently time-invariant integrated controllers suitable for use with the non-linear system are developed. These controllers incorporate model following with integral action and are shown to effect improved control of the nonlinear system over a wide range of operating conditions. The manner in which the proposed control system design procedure may permit the integrated control of large power systems is also of considerable pract...