Apparatus for automatic transmission shifting action, having device for learning compensation of control parameter influencing pattern of pressure change of frictional coupling device

An apparatus for controlling an automatic transmission of a motor vehicle, wherein a shifting action of the automatic transmission is achieved by releasing one of two hydraulically operated frictional coupling devices while at the same time engaging the other of said frictional coupling devices, said apparatus comprising:

• rapid pressure reduction means for rapidly reducing a pressure of said one of said two hydraulically operated frictional coupling devices to a predetermined pressure level, upon determination that said shifting action of the automatic transmission should be achieved;
• releasing pressure hold means for holding the pressure of said one of said two frictional coupling devices at said predetermined pressure level for a predetermined hold time;
• continuous pressure reduction means for continuously reducing the pressure of said one frictional coupling device at a predetermined reduction rate upon expiration of said predetermined hold time;
• and
• learning compensation means for updating, by learning compensation, a control parameter which influences a pattern of change of the pressure of said one frictional coupling device during said shifting action, such that said shifting action is achieved in a predetermined manner.