Method for controlling an automatic transmission for real-time compensation of changing friction properties of a clutch in the transmission

摘要

A method of controlling an automatic transmission having a clutch, the method comprising: estimating an expected coefficient of friction of the clutch; estimating a value of an expected torque required for a current input torque (34) applied to the transmission, maintain a constant slip (28) of the clutch; determining a value of actual torque applied to the clutch to maintain constant slip (28) of the clutch at the current input torque (34); calculating an actual coefficient of friction of the clutch, wherein the actual coefficient of friction of the clutch is calculated from the following equation: μact = (τactτexp) μexp, where µact is the actual coefficient of friction of the clutch, µexp is the expected coefficient of friction of the clutch, τact is the value of the actual torque applied to the clutch by which constant slip (28) the Maintain clutch and τexp is the value of the expected torque required to maintain constant slip (28) of the clutch; and setting an initial value of a feedforward torque command (38) applied to the clutch based on the calculated actual coefficient of friction of the clutch to define an enhanced value of the feedforward torque command (54).