Journal of Intelligent & Fuzzy Systems - Volume 6, issue 3

Authors: Titli, André

Article Type: Research Article

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 279-279, 1998

Authors: Pfeiffer, Bernd-Markus

Article Type: Research Article

Abstract: Different fuzzy logic approaches are applied for speed control of a 1.44 kW cooling blast engine. Selftuning of a classical PI controller by fuzzy rules provides the most simple solution. Higher control performance across the whole working range of this nonlinear process can only be achieved by using some knowledge about process behaviour. These informations in the form of a qualitative dynamic fuzzy model can be obtained from measured input/output data by fuzzy identification. The learning CoS (Center of Singletons) fuzzy system performing this identification is shown to be mathematically equivalent to a neural network with radial basis functions and is …therefore called a “neuro=fuzzy-structure”. Finally three different approaches for synthesis of a nonlinear control law are compared with respect to performance and design effort: imitation of human operators by fuzzy rules, imitation of classical controllers by fuzzy rules and fuzzy feedforward adaptation as qualitative feedback linearization. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 281-295, 1998

Authors: Valente de Oliveira, J. | Lemos, J.M.

Article Type: Research Article

Abstract: The development and application to a physical system of an adaptive predictive fuzzy controller is presented. The target process is a small electric furnace used in ceramic manufacturing. The proposed controller attempts to minimize a multi-step quadratic cost under the assumption that the control actions are all free over the prediction horizon. The control law relies on a simplified fuzzy relational model identified on-line. A convenient selection of the triangular norms used in the composition operator is made for allowing the application of Recursive Least Squares (RLS) to fuzzy relational structures, thus speeding up identification. It is shown that for …a particular selection of norms, relational structures require less parameters to be described, and they can be interpreted as a set of simplified fuzzy rules. Examples are presented in which the controller developed outperforms other controllers with identification procedures based on gradient. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 297-314, 1998

Authors: Holzmann, Henning | Germann, Stefan | Halfmann, Christoph | Isermann, Rolf

Article Type: Research Article

Abstract: As individual and commercial traffic flow on roads and highways grows enormously the number of traffic jams and accidents increases as well. Therefore, modern vehicle research is not only focused on adapting driving comfort to the growing traffic density in order to retain the advantages of individualized mobility, but also on improving passengers' safety. One way to improve safety and comfort of manually driven cars is to assist the driver by an Adaptive Distance and Cruise Control system (ACC). This paper deals with the design and implementation of a combined control structure using conventional techniques for vehicle acceleration control …on the one hand and fuzzy control algorithms for vehicle velocity and intervehicle distance control on the other hand. In this application, the major advantage using a fuzzy representation is the possibility to describe the subjective comfort and safety demands of drivers by linguistic formulation. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 315-327, 1998

Authors: Bailly, E. | Hayat, S. | Jolly, D. | Desodt, A.M.

Article Type: Research Article

Abstract: After a description of the regulation of the subway of Lille called VAL, we introduce a new model of regulation of line of subway based on fuzzy logic. This model takes in account, so as to regulate one train, not only its delay but also the delay of upstream and downstream trains. In a second time, to avoid the stacking of trains stopped in anticollision behind a disrupted train, we calculate indices of risk and no risk of blocking of the train between two stations based on the time of course between the trains and on the estimate of duration …of the train's disruption. The computation of risk can be done during a disruption intervening on the line and be extended in computing this index at each departure of one train from a station. We have simulated and tested our algorithm with the help of a simulation of subway's line achieved in object oriented language. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 329-343, 1998

Authors: Kaymak, U. | Babuška, R. | Nauta Lemke, H.R. van | Honderd, G.

Article Type: Research Article

Abstract: A fuzzy logic rule-based system for assessing steady-state security of a power network with a ring structure is presented. The system uses the measurements of the network state, the information about the network configuration, physical knowledge about the system and rules to determine the security class. The security is determined in a hierarchical manner, first at the component level and then at the network level. The rules are obtained from experts in the field of power systems, and describe the approximate behavior of the network based on knowledge about the physical principles and the network topology. A new defuzzification operator …is introduced, which allows the fuzzy logic system to follow different strategies such as risk aware operation. A graphical interface has been built for realizing effective interaction with the operators. The developed system has been tested on the 380 kV Dutch transmission network and it has been found that the classification corresponds to the opinion of experienced operators as to the security class. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 345-359, 1998

Authors: Sabbadin, Régis | Dubois, Didier | Prade, Henri | Grenier, Pierre

Article Type: Research Article

Abstract: The paper reports on a real case study coming from wine industry, which is an example of linear constraint satisfaction problem, where the constraints are flexible, may have different levels of priority or involve ill-known (imprecise or fuzzy) parameters. Fuzzy sets and possibility theory offer a unified framework that allows for the modelling of i) preferences between different ways of satisfying a flexible constraint, of ii) uncertainty pervading data, and of iii) priority among constraints. Indeed, actual constraints are often flexible and their satisfaction a matter of degree. That is why they are conveniently described by fuzzy sets. Uncertain …pieces of data can be represented by means of possibility distributions, and the level of priority of a constraint can be viewed as the maximum degree of acceptability of a solution that violates this constraint. In the following the fuzzy set-based approach to the handling of soft and uncertain constraints is presented and its interest is illustrated on the case study. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 361-374, 1998

Authors: Ludwig, Bjørn

Article Type: Research Article

Abstract: Discussions about Technology Assessment (TA) have increased in the last years. The aim is to provide entire knowledge about the consequences of recent and future applications of technologies. In this paper the problems of entire studies are treated. To ensure sustainability of technical applications it is necessary to consider unintentioned impacts and interactions. Performing such sustainable feasibility studies is characterized by modelling of the interactions between a technical system and its system environment. This is complicated by highly aggregated entities which resist a description with classical mathematics, like a formulation by a few elementary and measurable quantities. So the application …of classic-analytical tools is restricted. However, these entities can be modeled with the methods of soft computing. It is possible to identify and estimate consequences of technical applications by examining dynamic systems verbally. Even differential equations can be solved by computing with words using fuzzy logic, as shown in case of the recycling of waste paper and glas in Germany. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 375-388, 1998

Authors: Cardarilli, G.C. | Re, M. | Lojacono, R.

Article Type: Research Article

Abstract: In this paper, the realization of a new fuzzy processor is described. Original approaches are used for the implementation of both the fuzzifier and defuzzifier. The fuzzifier architecture is simplified by using input membership functions of suitable shape. The robustness of the fuzzy inference mechanism well tolerates this simplification. The defuzzifier uses the Center of Gravity (COG) method whose performance is improved by a new look-up table based computation. Moreover, the whole system has been simplified by accepting small approximations in the evaluation of the more expensive arithmetic operations. These approximations are obtained by supposing some constraints on the …input values and imply small errors in the final results. The proposed architecture is very efficient and its implementation requires small area. In fact, the layout of the processor, using a 1 μm CMOS technology, requires only 7 mm2 of silicon area. A speed greater than 100 KFLIPS is obtained with a 20 MHz clock. As consequence, this architecture can be used as a core cell in complex system integrating a whole processing structure. Show more

Citation: Journal of Intelligent and Fuzzy Systems, vol. 6, no. 3, pp. 389-401, 1998