Showing papers on "Open-loop controller published in 1972"

Dynamic Equivalents for Average System Frequency Behavior Following Major Distribances

Abstract: This paper endeavors to model the effects of governor- turbine dynamics on the average system frequency behavior of a multi- generator system after a major generation loss or load change when the system remains in synchronism. The maximum frequency deviation and the time at which the maximum occurs are the main quantities of interest. Two independent concepts are presented to convert a closed-loop, high dimensional, nonlinear model into approximate, open-loop, low dimensional, linear ones (the delay and the canonical models). The delay model uses pure time delay to model "fast time constants" and valve motion and converts the closed loop model into an open loop one. The canonical model expresses the turbine reheats respo'nse as a linear combination of a set of "basis" functions and provides a basis for combining many machines into one simplified, low dimensional model. The two models can be implemented concurrently, to give a very large reduction in complexity when a multi-machine system is analyzed.

Design of controllers for open-loop unstable multivariable system using inverse Nyquist array

Abstract: The application of Rosenbrock's inverse-Nyquist-array design method to a multivariable system which is openloop unstable is illustrated. The original system description arises in state-space form, and has more outputs than inputs. However, the design specifications allow the problem to be recast as a regulator design, and the openloop system is analysed to determine the best choice of measurements. A simple controller using only proportional gains is determined using the inverse-Nyquist-array design method such that the system is stable. A satisfactory dynamic and static performance is obtained by the addition of classical single-loop compensators.

Design of proportional-integral derivative controllers by the use of optimal-linear-regulator theory

Abstract: A method is presented whereby the use of optimal-linear-regulator theory leads to a controller for a generalised tracking problem so that the steady-state error in response to a step input is zero. This is accomplished by in corporating a signal proportional to the integral of the error into the controller, which, as a result, is insensitive to changes in system parameters.

Multi-function controller

Abstract: A single multi-function controller for an industrial selfpropelled materials handling truck incorporates all desired control functions except steering.

On the solution of some minimax problems

Abstract: In dynamic minimax and stochastic optimization problems frequently one is forced to use a suboptimal controller since the computation and implementation of the optimal controller based on dynamic programming is impractical in many cases. In this paper we study the performance of some suboptimal controllers in relation to the performance of the optimal feedback controller and the optimal open-loop controller. Attention is focused on some classes of, so called, open-loop-feed-back controllers. It is shown under quite general assumptions that these open-loop-feedback controllers perform at least as well as the optimal open-loop controller. The results are developed for general minimax problems with perfect and imperfect state information. In the latter case the open-loop-feedback controller mkes use of an estimator which is required to perform at least as well as a pure predictor in order for the results to hold. Some of the results presented have stochastic counterparts.

Controller having gain selectable independently of controller output

Abstract: A process controller having selectable feedback networks for changing the controller gain independently of the controller output. Each feedback network includes proportional and rate control circuitry. When a particular feedback network is not connected in the feedback path of the controller, it is connected to ground and its rate capacitor is discharged, thereby allowing a smooth transfer of control when the feedback network is switched into the controller circuit.

Digital system for controlling traffic signals

Abstract: System for controlling traffic signals in which a local controller is located at each controlled intersection, respectively, to control the operation of a traffic signal at its associated intersection. A central controller is connected to the local controllers for the transmission of signals thereto. The central controller is programmed to provide output data which activate the local controllers. The data includes two digital words. One digital word selects the local controller to be activated and the other digital word selects the phase to which the selected local controller is to be advanced. The selected local controllers are operated by the central controller for controlling the traffic lights at their associated intersections. Each local controller includes a set of timers for controlling intervals that are program invariants. The local controllers will continue to operate in a fixed time mode in the absence of an overriding signal for the local controllers. When a local controller is activated by the central controller to advance to a designated light phase, the local controller will advance to the appropriate vehicle clearance interval and to time-out this interval independently before advancing the intersection lights to the phase designated by the central controller.

A self-organizing time-optimal controller†

Abstract: A kind of self-organizing controller is proposed, which can accomplish time-optimal control of the unknown plant through adaptation. The self-organizing controller consists of the controller which has a variable switching surface and the adaptation logic net which observes the state of the controlled plant and the control signal yielded by the controller. It can improve the parameters of the controller according to the adaptation algorithm. The proposed method required neither information on the plant dynamics nor its identification. Adaptation is carried out on line. Computer simulation shows the effectiveness of the method.