Patent ID: 8406972

Claim:
A control device for an automatic transmission which modifies a speed ratio between an input shaft connected to an engine side of a vehicle and an output shaft connected to a driving system of the vehicle, the control device comprising: vehicle speed detecting means for detecting an actual vehicle speed that is a traveling speed of the vehicle; vehicle speed estimating means for calculating an estimated vehicle speed 2 (VSP 2 ) that is a target future vehicle speed at a predetermined time based on the actual vehicle speed and an acceleration component speed; target gear shift ratio calculating means for calculating a target gear shift ratio based on a predetermined driving state signal including the VSP 2 ; and gear shift control means for controlling the automatic transmission based on the target gear shift ratio, wherein the vehicle speed estimating means comprises: a vehicle speed deviation calculation section configured to calculate a vehicle speed deviation between the actual vehicle speed and an estimated vehicle speed 1 (VSP 1 ); an estimated vehicle speed 2 calculation section configured to calculate the VSP 2 based on a result of integral calculation of an integration for the vehicle speed deviation with a predetermined gain; an estimated vehicle speed 1 calculation section configured to calculate the VSP 1 by means of a delay element performing a predetermined delay operation based on the VSP 2 ; and a gain modification section configured to make the predetermined gain small when the result of integral calculation is greater than a first predetermined value based on the actual vehicle speed, the gain modification section being operated only when an accelerator pedal opening angle is larger than a second predetermined value of the accelerator pedal opening angle.