Driving state monitoring apparatus for vehicles

A driving state monitoring apparatus for a vehicle, for monitoring the driving state of a driver of said vehicle, comprising:

• behavior parameter detecting means for detecting a behavior parameter indicative of an amount of lateral movement of said vehicle;
• vehicle speed detecting means for detecting the vehicle speed of said vehicle;
• behavior reference setting means for obtaining a simple regression line according to changes in the behavior parameter and setting the simple regression line as a behavior reference;
• lateral deviation behavior quantity calculating means for calculating a lateral deviation behavior quantity of said vehicle according to the behavior parameter, the behavior reference, and the vehicle speed;
• driving state determining means for determining whether or not the driving state of the driver is proper according to the lateral deviation behavior quantity;
• and
• road shape determining means for determining the shape of the road on which said vehicle is running;
• wherein when said road shape determining means determines that the road is substantially straight or curved with a substantially constant radius of curvature, and said driving state determining means determines that the driving state of the driver is not proper, it is determined that the driving state of the driver is abnormal;
• and
• wherein said road shape determining means estimates the radius of curvature of the road on which said vehicle is running and determines the shape of the road according to the estimated radius of curvature and a change rate of the estimated radius of curvature.