Gear-change control system for an automatic transmission

Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control

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Details

731181, F16H 6100, F16H 5900, B60K 4104

Patent

active

059117702

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a gear-change control system for an automatic transmission and has the features stated in the preamble of the main claim.
DE-A 42 15 406 has disclosed a control system for switching an automatic transmission which works according to fuzzy logic methods. This control system is based on an optimated control system in which all the fuzzy production rules are divided into separate fractions.
Together with driving modes maintained for long periods of time, a series of spontaneous driving modes are conditioned by situations (for example, cornering, short downhill or uphill distances). The fusion of such driving modes conditioned by situations is especially problematic in conventional control systems, since precisely defined start or end positions often cannot be given. For this reason, a threshold inquiry is difficult or impossible to make. Recourse is had, in this case, to time steps or time elements which, of course, cannot be adapted, or can be adapted only at great expense, to the time varying driving modes.
The problem on which this invention is based is to indicate means to be used in a control system, of the above mentioned kind, which allow a simple threshold inquiry for taking driving modes, conditioned by situations, into consideration.
The problem on which the invention is based is solved by the fact that in order to take into consideration situation-conditioned driving modes, a fuzzy logic module is used which imitates the operating method of a logic flip-flop and, in addition, allows continuous intermediate values.
According to the basic principles of the fuzzy logic, the input and output value ranges of this fuzzy-flip-flop are continuous so that the "set" and "release" conditions are provided with a kind of plausibility weight. The output quantity of said fuzzy-flip-flop is thus always a compromise of the existing input quantities which, in turn, can result from a fuzzy control system as flat quantities. Other advantageous designs of the control system, according to the invention, are to be understood from claims 2 to 10.
Herebelow is explained in detail, by way of example with the aid of drawings, the realization of a control system according to the invention involving a fuzzy-flip-flop. In the drawings:
FIG. 1 is a simplified block diagram of a rule-based fuzzy-flip-flop; and
FIG. 2 is a flow chart of a fuzzy-flip-flop with a system performance modelled by an algorithm.
In tying in driving modes conditioned by situations, the fact that precisely defined start and end features (for example, change of the throttle valve position<20%, etc.) often cannot be given is problematic. For this reason, a threshold inquiry is difficult or impossible. In most cases, time steps or time elements are used which can, if at all, be adapted to the time varying conditions only at great expense.
Advantageous here is the use of a fuzzy logic module which imitates the operating method of a logical flip-flop. A realization based on rules or an algorithmic realization, using fuzzy logic methods combined with a system of internal storage of conditions, is possible.
The module, according to FIG. 1, has two inputs available by which an event-controlled "set" or "release" output can be given. According to the basic principles of the fuzzy logic, the input and output value ranges of said fuzzy-flip-flop are continuous so that the "set" or "release" modes are provided with a kind of plausibility weight. The output quantity of this fuzzy-flip-flop is thus always a compromise of the existing input quantities which, in turn, are generated again by a fuzzy control system as flat quantities (see FIG. 1). Pursuant to the logical flip-flop, the fuzzy-flip-flop can also issue a fuzzy negation of the output quantity.
The above described system performance of the fuzzy-flip-flop can, in principle, be modelled by different theoretical arrangements.
FIG. 2 shows a flow chart, of the operating method of a fuzzy-flip-flop, based on an algorithmic realization. The algorithm used is essentially based on the input

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