Showing papers on "Control theory published in 1973"

Wide-sense adaptive dual control for nonlinear stochastic systems

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.

Pipeline signal processor

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.

Sufficiently informative functions and the minimax feedback control of uncertain dynamic systems

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

Observing systems with unmmeasurable inputs

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.

Auxiliary control for a blood pump

Abstract: An auxiliary control for a blood pump used in hemodialysis which acts upon an existing blood pump controller to continuously vary the pump rate in direct correspondence with changes in flow of a patient''s blood reflected as variations in negative pressure in a blood line. The auxiliary control regulates the pump rate by producing an electrical pulse train in which the duration of the pulses corresponds to changes in negative pressure corresponding to changes in the blood flow rate. The control presents means for achieving a rapid response to changes in the flow of the patient''s blood.

Automatic Generation Control Part II-Digital Control Techniques

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.

Design and analysis of boiler-turbine-generator controls using optimal linear regulator theory

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.

Automatic self-testing programmable industrial controller

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.

Controller for injection molding machine

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.

On practical stability

Abstract: In this paper, a class of non-linear non-autonomous systems with multiple non-linearities is considered. Sufficient conditions are developed for a type of practical stability with specified settling time. The conditions are independent of the actual Form of the non-linear characteristics so that they can be interpreted as conditions for ‘absolute’ practical stability. The stability test is reduced to verification of the Hurwitz property of a constant matrix. This makes the stability analysis of the considered class of non-linear systems convenient for machine computations The proposed practical stability analysis is applied to a third-order system with several non-linearities.

The sensitivity of nominally time-optimal control systems to parameter variation†

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

Presence sensing and self-checking control system

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.

Traction motor controller circuit and method

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.

Modified Quasilinearization Algorithm for Optimal Control Problems with Nondifferential Constraints. Part 1, Theory,

Abstract: : In a previous paper, Miele, Mangiavacchi, and Aggarwal developed the modified quasilinearization algorithm for minimizing a functional subject to differential constraints, nondifferential constraints, and terminal constraints. In the report, several numerical examples are presented, some pertaining to the fixed-final-time case and some pertaining to the free-final-time case. Both equality constrained optimization problems and inequality constrained optimization problems are investigated. The numerical results show the rapid convergence characteristics of the modified quasilinearization algorithm. (Author)

Solar Pressure Control of a Dual-Spin Satellite

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.

Multi port flow controller

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.

Pid controller for heating, ventilating and air conditioning systems

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.

Dynamical Polysystems and Control Theory

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.

An optimal learning algorithm for S-model environments

Abstract: A class of stochastic automata models is proposed for the synthesis of a parameter optimizing controller. The automaton can operate in environments characterized by reward strengths ( S -models) or reward probabilities ( P -models). In the P -model case the proposed algorithm is equivalent to the e-optimal algorithm reported by Shapiro and Narendra. The algorithm discussed here was originally reported by Mason with emphasis on the P -model case. In this paper, emphasis is placed on the S -model case. Recently, an equivalent e-optimal algorithm has been reported by Viswanathan and Narendra. It is Shown herein that only the optimal solution is stable and that the expected performance converges monotonically. Simulation results are presented that corroborate the analytical results. It is demonstrated that the proposed algorithm is superior tO McLaren's linear reinforcement scheme in regard to expediency.

Temperature controller for controlling both heating and cooling

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.

On the structure of optimal area controls in electric power networks

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.

System for controlling processing equipment

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.

Precision temperature controller

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.

Identification and Control of Multivariable Stochastic Feedback Systems

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.