Patent ID: 8260501

Claim:
An awake state estimation device that determines whether a driver of a vehicle is awake or asleep based on a steering angle of the vehicle, comprising: a traveling information acquisition portion that acquires from the vehicle traveling information that changes according to a type of a traveling path on which the vehicle is moving, the traveling information including an absolute steering angle that is a rotation angle of a steering handle, an average steering angle that is a moving average value of the absolute steering angle, an average steering angular speed that is a differential value of the average steering angle, and a traveling speed of the vehicle; a corrective steering angle calculation portion that calculates, as a corrective steering angle, a difference between the absolute steering angle and the average steering angle acquired by the traveling information acquisition portion; a storage portion that pre-stores a plurality of correction values for the corrective steering angle in association with respective variables that are the absolute steering angle, the average steering angular speed, and the traveling speed, the storage portion pre-storing the plurality of correction values as a correction value map in which the plurality of correction values and the traveling information are associated with a plurality of ranges set based on magnitudes of the variables and the plurality of ranges correspond to types of traveling paths; a correction value setting portion that sets the correction value based on the traveling information acquired by the traveling information acquisition portion, the correction value setting portion selecting from the plurality of ranges a range that contains a value of the traveling information acquired by the traveling information acquisition portion, and setting the correction value that is associated with the range; a corrective steering angle correction portion that corrects the corrective steering angle calculated by the corrective steering angle calculation portion, by using the correction value set by the correction value setting portion; and an awake state estimation portion that determines whether the driver is awake or asleep based on the corrective steering angle corrected by the corrective steering angle correction portion.