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Showing papers on "Control theory published in 1973"


Journal ArticleDOI
TL;DR: In this paper, a new approach is presented for the problem of stochastic control of nonlinear systems, which takes into account the past observations and also the future observation program.
Abstract: A new approach is presented for the problem of stochastic control of nonlinear systems. It is well known that, except for the linear-quadratic problem, the optimal stochastic controller cannot be obtained in practice. In general it is the curse of dimensionality that makes the strict application of the principle of optimality infeasible. The two subproblems of stochastic control, estimation and control proper, are, except for the linear-quadratic case, intercoupled. As pointed out by Feldbaum, in addition to its effects on the state of the system, the control also affects the estimation performance. In this paper, the control problem is formulated such that this dual property of the control appears explicitly. The resulting control sequence exhibits the closed-loop property, i.e., it takes into account the past observations and also the future observation program. Thus, in addition to being adaptive, this control also plans its future learning according to the control objective. Some preliminary simulation results illustrate these properties of the control.

172 citations



Patent
02 Nov 1973
TL;DR: In this article, a signal processor including a programmable arithmetic controller and a pipeline arithmetic unit controlled by such controller is described, where the arithmetic unit includes a plurality of serially coupled processing levels.
Abstract: A signal processor including a programmable arithmetic controller and a pipeline arithmetic unit controlled by such controller is disclosed. The arithmetic unit includes a plurality of serially coupled processing levels. The arithmetic controller includes a corresponding plurality of serially coupled control levels, each one of such control levels being coupled to a corresponding one of the processing levels. Each one of the processing levels passes digital data applied thereto in accordance with a control instruction applied to such processing level by the arithmetic controller. As data passes through the various processing levels, the control instruction associated with such data passes through the corresponding control level so that such control instruction ''''follows'''' such data as both data and control instruction pass through the processor. In this way the processor is adapted to start a new process concurrently as such processor completes a prior process.

115 citations


Journal ArticleDOI
TL;DR: The idea of a sufficiently informative function, which parallels the notion of a sufficient statistic of stochastic optimal control, is introduced, and conditions under which the optimal controller decomposes into an estimator and an actuator are identified.
Abstract: The problem of optimal feedback control of uncertain discrete-time dynamic systems is considered where the uncertain quantities do not have a stochastic description but instead are known to belong to given sets The problem is converted to a sequential minimax problem and dynamic programming is suggested as a general method for its solution The notion of a sufficiently informative function, which parallels the notion of a sufficient statistic of stochastic optimal control, is introduced, and conditions under which the optimal controller decomposes into an estimator and an actuator are identified A limited class of problems for which this decomposition simplifies the computation and implementation of the optimal controller is delineated

105 citations


Journal ArticleDOI
TL;DR: In this article, an observability test for existence of a dynamic feedback controller and relations for its dynamic order are presented for linear systems with unknown disturbances, where the disturbances satisfy differential equations with arbitrary characteristic roots and where the state is not directly available for measurement.
Abstract: Known results on dynamic feedback controllers for linear systems with unknown disturbances are extended to cases where the disturbances satisfy differential equations with arbitrary characteristic roots and where the state is not directly available for measurement. An observability test for existence of the controller and relations for its dynamic order are presented.

86 citations


Journal ArticleDOI
TL;DR: Non-conventional control logic is described with non-linear filtering features designed to be effective in following basic load trends and large deviations while reducing control action in response to the higher frequency random components.
Abstract: Techniques are described for the application of automatic digital generation control and for the evaluation of performance from indices which measure the effectiveness of control relative to the control effort. The basic objectives of generation control are reviewed and non-conventional control logic is described with non-linear filtering features designed to be effective in following basic load trends and large deviations while reducing control action in response to the higher frequency random components. Examples of simulations are included.

60 citations


Journal ArticleDOI
TL;DR: In this article, an approach to control system design based on optimal linear regulator theory and which recognizes the limitation of an imperfect model has been developed, which produces "integral-type" action which guarantees zero steady-state errors.
Abstract: The demand for improved dynamic response of fossil-fired power plants has motivated a comprehensive program of control system design and analysis. Previous papers have reported the development of a nonlinear mathematical model of a drum-type, twin furnace, reheat boiler-turbine-generator (RBTG) system which is suitable for control system analysis and has been extensively verified by field test. On the basis of this model, local stability, observability, and controllability have been examined over the load range, using linearization and modal analysis. An approach to control system design has been developed based on optimal linear regulator theory and which recognizes the limitation of an imperfect model. This approach produces "integral-type" action which guarantees zero steady-state errors. The controller does not require complete state feedback. Improved performance has been demonstrated by comparison with the existing control structure through simulation using the nonlinear process model.

57 citations


Patent
22 Feb 1973
TL;DR: In this paper, a programmable industrial logic controller is provided for accomplishing the sequencing operations and other related control tasks performed by a logic control system of the type adapted for controlling machine and process equipment.
Abstract: A programmable industrial logic controller is provided for accomplishing the sequencing operations and other related control tasks performed by a logic control system of the type adapted for controlling machine and process equipment. The controller includes input means, memory means, control logic means, automatic self-test means, output means and manual test means. The input means functions to receive inputs supplied to the controller corresponding to the existing conditions of a plurality of parameters of the equipment being controlled. A pre-established set of instructions is stored in the memory means relating to the operation of the equipment being controlled. The control logic means functions to operate in response to a set of instructions stored in the memory means. Further, the control logic means functions to generate outputs, for controlling the operation of the equipment, from the series of instructions extracted from the memory means. Automatic self-test means are provided for periodically performing a self test of the controller to determine whether the controller is functioning properly. The output means is connected in circuit relation with control logic means and receives therefrom the outputs generated thereby. The outputs received by the output means are supplied thereby to the equipment being controlled. The manual test means are provided to permit manual test of selected controller functions.

52 citations


Patent
06 Apr 1973
TL;DR: In this paper, the authors present a control circuitry for monitoring a number of predetermined process conditions for controlling the quality and consistency of injection molded articles, which consists of a hydraulic pressure transducer and a cavity pressure transducers.
Abstract: In an injection molding machine there is provided control circuitry for monitoring a number of predetermined process conditions for controlling the quality and consistency of injection molded articles. The system comprises a hydraulic pressure transducer and a cavity pressure transducer employed in concert with the control circuitry which monitors the viscosity of the article presently being formed, provides a corrective adjustment during the present cycle when the measured viscosity deviates from a reference viscosity, compares the applied hydraulic pressure with a hydraulic reference pressure, and measuring the peak cavity pressure during one cycle in order to control the applied pressure during the subsequent cycle as a function of the previously measured peak cavity pressure.

52 citations


Journal ArticleDOI
TL;DR: In this article, the effect of plant parameter variations on systems with nominally time-optimal feedback controllers is investigated, assuming that the plant parameter remains constant and that the timeoptimal controller calculated for the nominal plant parameter is used.
Abstract: The effect of plant parameter variations on systems with nominally time-optimal feedback controllers is investigated. It is assumed that the plant parameter remains constant and that the time-optimal controller calculated for the nominal plant parameter is used. For higher-order systems remarkably small deviations of the plant parameter from its nominal value are found to yield instability. A sub-optimal controller design which results in sliding motion ensures stability and yields acceptable settling time for moderato parameter variations

48 citations


Patent
29 Jan 1973
TL;DR: In this paper, a presence sensing system provided with self-checking operation is described, which is especially adapted for use in a control system for machines to ensure safe operation of the machines.
Abstract: A presence sensing system provided with self-checking operation is disclosed. The system is especially adapted for use in a control system for machines to ensure safe operation thereof. The system comprises a presence sensing section capable of producing output signals indicative of normal, intrusion, and withdrawal conditions in the guarded zone of the machine. A control system comprising a control channel and a self-checking channel responds to the output signals of the sensing section and control the condition of a controller, which in turn is adapted to interrupt machine operation. The control channel and the self-checking channel are both implemented in binary logic. The system is operated under the control of timing means which causes cyclic operation with each cycle divided into separate time slots, one for a testing mode of operation and one for a condition sensing mode of operation. The testing mode time slot is subdivided into plural time slots, each corresponding to a particular test of the system.

Patent
11 Jul 1973
TL;DR: A traction motor controller circuit and method in which the electronic switch supplying current to the motor is controlled as a function of load current between selected maximum and minimum limits is described in this paper.
Abstract: A traction motor controller circuit and method in which the electronic switch supplying current to the motor is controlled as a function of load current between selected maximum and minimum limits. A manually variable throttle signal is compared with the sum of a signal related to motor current and a feedback signal from the comparator to act as a Schmitt trigger circuit in controlling the conduction of the electronic switch supplying current to the motor.

Journal ArticleDOI
T.R. Kyle1, George J. Zydzik1
TL;DR: In this article, a control circuit for pulling uniform cross section crystals from the melt is described, where the output of a sensor that monitors an R.F. power source is compared to a reference voltage by a controller and the difference is used to adjust the current to a saturable core reactor that feeds a generator.

Journal ArticleDOI
TL;DR: In this article, the attitude control of a spinning satellite using solar radiation pressure is studied for the general case of attutide motion in an arbitrary orbit, and the response data, presented as functions of the system parameters, show the controller's effectivenss in damping the most severe disturbances in a fraction of an orbit.
Abstract: Nutation damping and attitude control of a spinning satellite using solar radiation pressure is studied for the general case of attutide motion in an arbitrary orbit. The nonlinear, nonautonomous, coupled equations of motion involving large numbers of parameters are only amenable to a numerical approach. The response data, presented as functions of the system parameters, show the controller's effectivenss in damping the most severe disturbances in a fraction of an orbit. The controller provides versatility to the satellite, enabling it to change its preferred orientation in orbit and, hence, undertake diverse missions. An illustrative example using mass properties representative of INTELSATIV and the Canadian communications satellite (Anik-1) demonstrates the feasibility of the concept. The semipassive character promises an increased lifetime with an effective reduction in cost.

Patent
05 Jun 1973
TL;DR: In this paper, a volume regulator box in an air distribution system makes secondary use of control air, secondary bleed nozzles are used in a way that eliminates the need for high pass and low pass control relays.
Abstract: A controller for a volume regulator box in an air distribution system makes secondary use of control air. Secondary bleed nozzles are used in a way that eliminates the need for high pass and low pass control relays, mechanical interlock between such control relays and high control pressures. The controller is of modular construction with each module performing a separate control function. A single controller design can be adapted to different uses, such as a maximum velocity control in a high static pressure application or a maximum and minimum velocity control in a low pressure application.

Patent
14 May 1973
TL;DR: In this paper, a proportional integrator (PI) circuit is arranged to receive the output signal from a differentiator (D) circuit which has been delayed and inverted in a summing circuit together with an input control signal to provide a PID controller having a negative delayed D influence.
Abstract: A heating and/or air conditioning system including a novel controller of the PID type. A proportional integrator (PI) circuit is arranged to receive the output signal from a differentiator (D) circuit which has been delayed and inverted in a summing circuit together with an input control signal to thereby provide a PID controller having a negative delayed D influence. Such controllers are sometimes referred to as a PIminus-D controller. The circuit employs operational amplifiers and the time delay provided by the differentiator circuit is 7 minutes as compared with the time constant of approximately 2 minutes for the integrator and the PI portion of the circuit. The PID controller as disclosed operates through a broad range of frequencies between about 20 seconds and 50 minutes to produce a substantially optimum regulation of the fuel or heat exchanging medium control valve without the need for a separate field adjustment by the installation mechanic.


Book ChapterDOI
01 Jan 1973
TL;DR: In this paper, it is shown how it is possible to generalize many results on controllability of linear control systems to the nonlinear ones, by making use of basic definitions of differential geometry.
Abstract: In these lectures we shall see how it is possible to generalize many results on controllability of linear control systems to the nonlinear ones. A little use of basic definitions of differential geometry is made ; the necessary material used is exposed in appendix.


Journal ArticleDOI
TL;DR: In this paper, a solution is given to yield reset control action in multivariable control systems, where the controller consists of a state reconstructor and feedback from estimated process and environmental states, and if a special choice for the ''feedforward'' matrix operating on the estimated environmental states is made, integral, or reset, control action results.

Patent
10 Jan 1973
TL;DR: In this paper, a temperature controller for maintaining the temperature of a process at a set point by controlling the heating input in accordance with both a proportional and reset response from the temperature deviation is presented.
Abstract: A temperature controller for maintaining the temperature of a process at a set point by controlling the heating input in accordance with both a proportional and reset response from the temperature deviation. When the deviation indicates that the temperature control requires a cooling input to the process, a gating signal is produced. Another gating signal is produced when the manipulated variable providing the heating input is below a preset value. Gating means are provided which will respond to the coincidence of the two gating signals for introducing the cooling to the process. The cooling is thus controlled in an on-off mode.

Journal ArticleDOI
TL;DR: In this paper, an optimal feedback controller is synthesized for the case of two-generator load sharing, where the maximal principle is modified for this situation, and necessary conditions for an optimal controller are obtained for the general case of n generators.
Abstract: Static optimization techniques have been used by the electric power industry for several years to solve the problem of economic load allocation. Experience has shown that difficulties frequently arise when these solutions are incorporated in the feedback control of dynamic electric power networks. In a recent paper, economic load allocation was formulated as a dynamic optimal control problem in an effort to overcome the disadvantages of controllers currently used. At the heart of that problem is the area control problem that is treated in detail in this paper. An unusual feature of the area control problem is that it contains kinks. The maximal principle is modified for this situation. Necessary conditions for an optimal controller are obtained for the general case of n generators. The optimal feedback controller is synthesized for the case of two-generator load sharing.

Patent
Arthur P. Given1
09 Apr 1973
TL;DR: A control system for use with processing equipment includes a controller and a plurality of addressable terminal devices including means for transferring data between the processing equipment and the controller over a common bus as discussed by the authors.
Abstract: A control system for use with processing equipment includes a controller and a plurality of addressable terminal devices including means for transferring data between the processing equipment and the controller over a common bus.

Patent
Way Allan S1
22 Feb 1973
TL;DR: In this paper, a precision temperature controller utilizing a temperature sensitive resistive element in thermal relationship to an object to be heated, the element being connected in a bridge circuit to derive an error signal proportional to deviation from a desired temperature, the error signal being summed with a sawtooth voltage, the output so obtained being compared with a reference voltage in an operational amplifier to derive a pulsed output having a pulse width proportional to the error signals.
Abstract: A precision temperature controller utilizing a temperature sensitive resistive element in thermal relationship to an object to be heated, the element being connected in a bridge circuit to derive an error signal proportional to deviation from a desired temperature, the error signal being summed with a sawtooth voltage, the output so obtained being compared with a reference voltage in an operational amplifier to derive a pulsed output having a pulse width proportional to the error signal, the pulse width being used to control the time duration of energization of a heating element in proximity to the resistive element.

Journal ArticleDOI
01 Jan 1973
TL;DR: In this paper, the authors consider the problem of simultaneous identification and control of stochastic processes characterized by linear dynamic models with unknown systems parameter coefficients, and derive consistent identification algorithms for the case in which arbitrary feedback controls are present.
Abstract: This paper considers the problem of simultaneous identification and control of stochastic processes characterized by linear dynamic models with unknown systems parameter coefficients. Stochastic approximation is used to derive consistent identification algorithms for the case in which arbitrary feedback controls are present. These identification methods can also be used for determining the order of the system, if the latter is unknown, as well as the exact canonical structure for the multivariable case. An approximation to the optimal control solution is obtained by explicitly separating the functions of identification and control, and asymptotic convergence to a stochastic optimal controller is attained without on-line structural modification.

Patent
15 Aug 1973
TL;DR: A feedback regulated electronic shaft angle and rate measuring circuit for use in an electronic spark timing angle advance and retard controller for an internal combustion engine ignition system is described in this paper, where the circuit is used to measure the rate and angle of the shaft angle.
Abstract: A feedback regulated electronic shaft angle and rate measuring circuit for use in an electronic spark timing angle advance and retard controller for an internal combustion engine ignition system.

01 Apr 1973
TL;DR: A flight control system design is presented that can be implemented by analog hardware, to be used to control an aircraft with uncertain parameters, based upon the use of modern control theory.
Abstract: A flight control system design is presented, that can be implemented by analog hardware, to be used to control an aircraft with uncertain parameters. The design is based upon the use of modern control theory. The ideas are illustrated by considering control of STOL longitudinal dynamics.

Patent
05 Oct 1973
TL;DR: A steam turbine is provided with an automatic digital computer controller and a backup analog controller which are interfaced with an electrohydraulic position control for the turbine throttles and governor valves as discussed by the authors.
Abstract: A steam turbine is provided with an automatic digital computer controller and a backup analog controller which are interfaced with an electrohydraulic position control for the turbine throttles and governor valves. Valve position signals are generated by transducers and applied to the valve position control along with position setpoint signals from the computer or the backup controller for the purpose of generating valve control signals which drive the valves until the position setpoints are satisfied. The position signals are also applied to the computer where they are compared to the computer valve position setpoints. The automatic controller and the analog backup controller each have a speed/load control which generates the valve position setpoints in accordance with a speed or load reference, and the backup control tracks the computer setpoints during automatic control. The backup control position setpoint signals are also applied to the computer during automatic control there they are also compared to the computer valve position setpoints. If any comparison results in a difference in excess of a predetermined deadband valve, the computer generates a contingency signal to indicate a valve not functioning or backup not tracking.

Journal ArticleDOI
TL;DR: An adaptive control scheme is proposed which has terms in the Liapunov function used in the design procedure which are not included in previously proposed schemes.
Abstract: This paper considers the model-reference adaptive control problem which has received considerable attention in the literature in the last few years. An adaptive control scheme is proposed which has terms in the Liapunov function used in the design procedure which are not included in previously proposed schemes. The relationship of this new scheme to existing schemes is shown by considering the root-loci of the linearized error equations between plant and model. Finally, a second order example is given which illustrates the difference between the two previously proposed model-reference adaptive methods and the one proposed in this paper.

Journal ArticleDOI
TL;DR: In this article, the state regulator and tracking techniques have been used to design controller feedbacks to improve system performance and an eigenvalue search technique has also been applied to determine the desired controller gain and time constant.
Abstract: This paper applies the modern control theory to design HVDC controllers. The state regulator and tracking techniques have been used to design controller feedbacks to improve system performance. Both optimal and sub-optimal controllers have been designed. An 'eigenvalue search' technique has also been applied to determine the desired controller gain and time constant. Using the various designed controllers, the dynamic performance of the system has been studied on both a digital computer and a small scale simulator. Some of these time domain studies are included in addition to the root locus plots.