Controller for automatic transmission

A controller for a stepped automatic transmission,

• the stepped automatic transmission being configured to
• establish one of a plurality of speed positions by selectively engaging a plurality of frictional engagement elements and,
• when a power-on downshift is required and when there is a difference in speed position by two or more steps between a current speed position and a required speed position that is required in response to an operation status, perform multiple shifts that transitionally establish an intermediate speed position between the current speed position and the required speed position, the controller comprising
• an electronic control unit configured to
• at the time when a power-on downshift that performs the multiple shifts that transitionally establish an intermediate speed position is performed, control a surge hydraulic pressure that is supplied to each engaging frictional engagement element in order to increase response of the engaging frictional engagement element, each engaging frictional engagement element being controlled from a released state toward an engaged state in a corresponding one of the shifts, and
• set a surge hydraulic pressure for the engaging frictional engagement element that is operated when the intermediate speed position is transitionally established such that the surge hydraulic pressure for the engaging frictional engagement element that is operated when the intermediate speed position is transitionally established is lower than a surge hydraulic pressure for the engaging frictional engagement element that is operated when the required speed position is established.