Boots – shoes – and leggings
Patent
1994-10-24
1996-09-17
Teska, Kevin J.
Boots, shoes, and leggings
36443107, 395905, 477 43, B60K 4106
Patent
active
055575218
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a control system for changing automatic gears. It in particular concerns a control that makes use of fuzzy logic methods for determining the gear-changing point. There exist means (sensors, switches, etc.) for detecting input variables derived from a driver-vehicle system. Membership functions, that is, fuzzy sets, are produced for the input variables; means also exist for this. Means such as hydraulically actuatable gear clutches and valves have further been provided for changing gear ratios. The means for detecting the input variables and the means for producing membership functions and the means for changing the gear ratio work together in a specific manner. According to fuzzy-production rules, there are produced output variables with which a gear ratio is determined.
Automatic gears basically serve for adapting the torque delivered by a drive engine of a vehicle to the traction force thereof. Such automatic gears have an electronic hydraulic control. The electronic control possesses a primary importance for the whole driving behavior, since the gearshift operations are recognized and carried out with the aid of load-speed performance graphs.
Whether to change and to which gear depends on the load adjustment, that is, on the actual state of the throttle valve and of the output speed of the transmission. The individual gear steps are changed in accordance with gearshift characteristics formed from said two parameters. The gearshift characteristics of automatic gears consist of upshift and downshift straight lines for the individual gears, which in a gearshift diagram extend in a manner such that a hysteresis originates between the individual speed ranges. Despite said hysteresis, sharp decision thresholds finally determine whether and at what speed to change gears. The use of such sharp decision thresholds means, one hand, that only discrete, invariant conditions can lead to the triggering of a change-over operation and, on the other, that a distortion of the logical information contents of the decision is here systematically present. Said information can be explained with the aid of an example: when the throttle valve position is steady, a speed of 3000 revolutions/min. can, in the critical case, lead to a change of gear while at a speed of 2990 revolutions/min. no change of gear is started even though both system conditions are practically the same.
Other criteria can influence the design of a gear-change diagram by virtue of the position of the gear-change characteristics. In performance-oriented (sport) driving style, a relatively late upshift and an early downshift results. In a consumption-oriented (economic) driving style, the position of the characteristic lines is inclined toward a medium engine speed. The gear-change behavior of automatic gears can be changed by activating adaptive gear-change characteristics, that is, gear-change characteristics oriented toward the performance, the consumption, or special driving conditions.
Despite a multiplicity of possibilities already used for automated determination of the gear-change point, the purpose of approximating the automatic gear selection to the behavior of a human driver, especially of a certain type of driver, has been only imperfectly obtained.
A possibility of better representing a decision made by a human, such as is possible via threshold values or performance graphs, is the use of the fuzzy logic method. A fuzzy-inference system permits a decision in which a multiplicity of parameters are taken into account and is influenced by features of human decision making. A greater advantage of this method consists in allowing a direct processing of verbally formulated problem descriptions. Contrary to traditional control strategies, it is possible to use judgment criteria which cannot be expressed in mathematical description forms but plays a substantial part in the making of decisions.
An example of a control system for changing automatic gears making use of fuzzy logic methods can be seen in U.S. Pat. No. 4,841,815. The ve
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Danz Wolfgang
Eschrich Gerhard
Gillich Udo
Runge Wolfgang
Nguyen Tan
Teska Kevin J.
ZF Friedrichshafen AG
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