Boots – shoes – and leggings
Patent
1995-08-04
1997-11-11
Voeltz, Emanuel T.
Boots, shoes, and leggings
395 3, 395 61, 395 80, 395900, 364172, 3642746, G05B 1300
Patent
active
056870760
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method for adjusting scale factors of fuzzy controllers or conventional non-linear controllers.
2. Description of the Related Art
Method for adjusting scale factors of fuzzy logic controllers and conventional non-linear controllers.
In most cases, fuzzy controllers (FCs) operate such that on the basis of crisp desired values and controlled variables manipulated variables which are likewise crisp are applied to the system (see FIG. 1). In this most frequent application, the fuzziness is limited exclusively to the controller, which is more robust than conventional controllers with respect to parameter variations and quick changes in desired value. It has been established that systems having a non-linear characteristic and complicated structure can be controlled better by FCs than by conventional controllers. Compared with adaptive controllers, FCs require a far lower outlay on implementation and are more robust with respect to uncertainties in the modeling. If the fuzziness is limited exclusively to the controller, by including the fuzzification or defuzzification respectively upstream or downstream of the FC, the latter can be considered relative to the outside as a conventional non-linear controller.
Operating FCs of this type requires the fuzzification of the input variables (for example error and error rate): each crisp input variable is assigned to a subset of degrees of membership which depend on a set, selected a priori, of membership functions. For the sake of simplicity, in most cases the membership functions are defined inside a standardized interval (a universe of discourse). Consequently, before the fuzzification, the input variables must be standardized (scaled) in such a way that they fit into the standard interval. An optimum selection of scale factors is therefore essential, because a poorly selected scaling leads to a displacement of the operating range to the edges of the standard interval. Generally suitable scaling rules are disclosed in the literature (M. Braae, D. A. Rutherford: Selection of Parameters for a Fuzzy Logic Controller, Fuzzy Sets and Systems 2 (1979), North-Holland pages 185 to 199; Peng Xian-Tu: Generating Rules for Fuzzy Logic Controllers by Functions, Fuzzy Sets and Systems 36 (1990), North-Holland pages 83 to 89; T. J. Procyk, E. H. Mamdani: A Linguistic Self-Organizing Process Controller, Automatica Vol. 15 (1979), Pergamon Press Ltd. pages 15 to 30).
In these methods, optimum scaling depends not only on the characteristics of the input variables, but also to a certain extent on the form and arrangement of the membership functions and naturally also on the system dynamics. The disadvantage of some of the previous methods resides in that they are based on the method of trial and error (A. Boscolo, F. Drius: Computer Aided Tuning and Validation of Fuzzy Systems. IEEE Int. Conf. on Fuzzy Systems 1992 San Diego March 1992, pages 605 to 614). The known methods, which operate using cost functionals, have the disadvantage that they are limited to PID-similar FCs (Li Zheng: A Practical Guide to Tune PI-like Fuzzy-Controllers, IEEE Int. Conf. on Fuzzy Systems 1992 San Diego March 1992, pages 633 to 640).
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method for optimally adjusting scale factors in FCs. A fuzzy logic controller having crisp input variables and crisp output variables can be considered as a multidimensional, non-linear transfer element having upper and lower limits which is used in a control loop in which the system to be controlled has both linear and non-linear components. Fuzzy logic controllers are generally designed such that, on the one hand, they take account of the non-linearities and parameter fluctuations of the system by means of a high robustness. On the other hand, reference variables are to be adequately treated in accordance with their different quality, for example the aim should be an overproportional, non-linear approach
REFERENCES:
patent: 5166873 (1992-11-01), Takatsu et al.
patent: 5170341 (1992-12-01), Sklaroff
patent: 5241651 (1993-08-01), Ueda
patent: 5245528 (1993-09-01), Saito et al.
patent: 5247432 (1993-09-01), Ueda
patent: 5251124 (1993-10-01), Matsunaga
patent: 5295061 (1994-03-01), Katayama et al.
patent: 5396416 (1995-03-01), Berkowitz et al.
patent: 5587896 (1996-12-01), Hansen et al.
L. Zheng, "A Practical Guide to Tune of Proportional and Integral(PI) Like Fuzzy Controllers", IEEE International Conference on Fuzzy Systems, 8. Mar. 1992, San Diego, USA, pp. 633-640.
A. Boscolo, "Computer Aided Tuning and Validation of Fuzzy Systems", IEEE International Conference on Fuzzy Systems 1992 San Diego Mar. 1992, pp. 605-614.
T. Procyk et al., "A Linguistic Self-Organizing Process Controller", Automatica the Journal of IFAC the International Federation of Automatic Control, vol. 15, Jan. 1979, Great Britain, pp. 15-30.
M. Braae et al., "Selection of Parameters for a Fuzzy Logic Controllers", Fuzzy Sets and Systems 2 (1979), pp. 185-199.
D. Linkens et al., "Self-Organising Fuzzy Logic Control and the Selection of Its Scaling Factors", Transactions of the Institute of Measurement and Control, vol. 14, No. 3, 1992, Great Britain, pp. 114-125.
Peng, "Generating Rules for Fuzzy Logic Controllers by Functions", Fuzzy Sets and Systems 36 (1990), North-Holland, pp. 83-89.
"Fuzzy Logic in Control Systems: Fuzzy Logic Controller, Part II" By Chuen Chien Lee, IEEE Trans. on Systems, Man & Cybernetics, vol. 20, No. 2, pp. 419-435 Mar. 1990.
"Self-Tuning of a Fuzzy Logic Controller Using a Cell State Space Algorithm" By S. M. Smith & D. J. Comer, Systems, Man & Cybernetics, 1990 Int'l. Conference, pp. 445-450 Jun. 1990.
"An Algorithm for Automated Fuzzy Logic Controller Tuning" By S. M. Smith & D. J. Comer, Fuzzy Systems, Int'l. Conference 1992, pp. 615-622 Feb. 1992.
"Performance Evaluation of a Self-Tuning Fuzzy Controller" By Daugherity et al., Fuzzy Systems, Int'l. Conference 1992, pp. 389-397 Feb. 1992.
Dam Tuan Q.
Siemens Aktiengesellschaft
Voeltz Emanuel T.
LandOfFree
Method for adjusting scale factors of fuzzy logic controllers an does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for adjusting scale factors of fuzzy logic controllers an, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for adjusting scale factors of fuzzy logic controllers an will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1233718