Closed-loop adaptive fuzzy logic hydraulic pressure control for an

Abstract

A self-organizing fuzzy logic controller develops an adaptive pressure adder that modifies the magnitude of pressure supplied to a friction element of an automatic transmission. The controller uses a turbine speed versus engine torque table in KAM to store the adaptive pressure adder for each shift. Tables in KAM represent fuzzy rules which are altered based on shift performance criteria to produce a self-organizing fuzzy logic controller. The criteria, which define shift performance, include the ratio change slip time and torque converter turbine speed flare. The desired slip time is determined from a calibratable matrix. After a shifting event, an adaptive pressure adjustment is determined for the next shifting event of the same types. A two-input (slip time and turbine speed flare) fuzzy logic controller is used to determine the pressure adjustment. The adaptive pressure adjustment from the fuzzy controller is then increased if stage time is greater than a calibratable value. The adaptive pressure is also multiplied by a factor determined from the deviation in the throttle position reading for the shift event. Once the adaptive pressure is calculated, the adjustment is added to the cells of the adaptive pressure matrix that correspond to turbine speed and engine torque conditions.