Boots – shoes – and leggings
Patent
1995-12-26
1998-01-06
Ruggiero, Joseph
Boots, shoes, and leggings
364160, 395 61, G05B 1302
Patent
active
057061939
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates generally to control systems, and more particularly to a control system for a non-linear process varying in time, which includes two controllers, one of which is a linear PID controller, by means of which a manipulated variable (y) is determined from a comparison between a reference variable (w) and a controlled variable (x).
When conventional controllers, e.g. linear PID controllers, are used to control real processes, various problems arise. For non-linear processes, in particular, the parameters of a linear controller are only optimal for one operating point of the process. When working with discontinuous processes, changing operating points occurs when starting and stopping the process. The consequence may be an inadequate control response when a linear controller is used. In the same way, time-variant processes, whose behavior is variable because of external influences, such as fluctuating raw material quality, are problematic for linear controllers. In addition, in many processes there are interactions between individual process variables. When working with a conventional closed-loop control, the process is usually controlled with single-variable controllers. With this procedure, a plurality of single-loop control systems are employed, one for each of the individual process variables, while the interactions are disregarded. As a result, in certain process states, the closed-loop control may develop an unsatisfactory response, or instabilities may even occur. To resolve these problems, so-called higher control processes, e.g. with adaptive controllers, state controllers or model-supported controllers, are used. In practice, however, these higher control processes are only used infrequently, because their application presupposes extensive theoretical knowledge, and presupposes a process for which a mathematical model can be developed. The resultant outlay is often very high; to some degree, it is even impossible to describe a process mathematically. Therefore, in practice, a system operator must often intervene in the process, because, based on his experience, he will be able to recognize process states where the desired process behavior is not guaranteed by the conventional automatic control. The disadvantage associated with this is that because system operators have different levels of experience or even because their job performance can change from day to day, the result is a process control that is not reproducible.
The essay, "Fuzzy Control--werkzeugunterstutzte Funktionsbaustein-Realisierung fur Automatisierungsgerate und Automation Systems and Process Control Systems through the Support of Software Tools"! by Dr. Hans-Peter Preu.beta., Edmund Linzenkirchner and Steffen Alender, published in "atp" 34 (1992) issue 8, pp. 451-460, discusses avoiding these problems by adding a second controller to the conventional controller. It mentions using the output of the second controller for correcting manipulated variables, in order to support the conventional controller, as needed. In addition, the parameters Kp and Tv of the conventional PID controller are adapted with a further controller to the changing process dynamics. When these additional controllers are switched on, sudden changes in manipulated variables occur disadvantageously, which can lead to surge loads on the final controlling elements and, thus, to their rapid deterioration.
The present invention is directed to the problem of developing a control system, especially for a non-linear process varying in time, by using several controllers where surge loads on the final controlling elements caused by sudden changes in manipulated variables are avoided.
SUMMARY OF THE INVENTION
The present invention solves this problem by providing a control system of the type mentioned at the outset, in which: (1) the first controller is able to be switched over via a switching input between a "tracking" and a "control" operating mode, in the "tracking" operating mode, the manipulated variable (y) is
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atp Automatisierungstechnische Praxis, vol. 34, No. 8, Aug. 1992, Karlsruhe, FRG, pp. 451-460, H. Preuss et al.: Fuzzy Control--Werkzeugunterstutzte Funktionsbaustein-Realisierung fur Automatisierungsgerate und Proze.beta.leitsysteme (Fuzzy Control--Tool-aided Function Block Realisation for programamble Controllers and Distributed Process Control Systems).
1992 IEEE International Conference on Systems Man and Cybernetics, vol. 2, 18 Oct. 1992, Chicago, US, pp. 1603-1608, J. Zheng et al: STFC-Self-Tuning Fuzzy Controller.
Ruggiero Joseph
Siemens Aktiengesellschaft
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