Inference-based manual pulldown control of an automatic transmission

Abstract

A shift pattern control for a multiple speed ratio transmission wherein an inference-based control overrides the normal shift pattern to automatically achieve manual pulldown operation under conditions for which such operation would be advised and expected. The inference-based control is achieved with a fuzzy logic technique by which vehicle parameters influencing the desirability of manual pulldown operation are measured or estimated, and used to establish an aggregate measure of the overall need for engine braking and downshifting. In the preferred embodiment, the fuzzy logic parameters include vehicle speed, grade load, engine throttle position, time of braking and time of deceleration. The parameters are applied to membership functions to indicate the truthfulness of the specified conditions, and logical combinations of the truth indications are formed, weighted to reflect their criticality, and combined to form an aggregate measure of the overall need for pulldown operation.

Dependencies are inferred from the claim text.