Driver assistance device, driver assistance method, and non-transitory computer-readable storage medium storing program

A driver assistance method for a vehicle that is configured to automatically decelerate the vehicle in accordance with a relative relation between the vehicle and a vehicle traveling ahead that is traveling forward of the vehicle, and change deceleration of the vehicle by a first change amount, or a second change amount that is larger than the first change amount, when automatically decelerating the vehicle, the driver assistance method comprising:

• estimating whether behavior of the vehicle will become unstable when the vehicle automatically decelerates;
• maintaining the deceleration of the vehicle by the second change amount when automatically decelerating the vehicle, when the behavior of the vehicle is estimated to not become unstable;
• and
• changing the deceleration by the first change amount when automatically decelerating the vehicle, when the behavior of the vehicle is estimated to become unstable.

A non-transitory computer-readable storage medium storing a program that, when executed by a processor of a driver assistance device configured to automatically decelerate a vehicle in accordance with a relative relation between the vehicle and a vehicle traveling ahead that is traveling forward of the vehicle, causes the driver assistance device to:

• change deceleration of the vehicle by a first change amount, or a second change amount that is larger than the first change amount, when automatically decelerating the vehicle;
• estimate whether behavior of the vehicle will become unstable when the vehicle automatically decelerates;
• maintain the deceleration of the vehicle by the second change amount when automatically decelerating the vehicle, when the behavior of the vehicle is estimated to not become unstable;
• and
• change the deceleration by the first change amount when automatically decelerating the vehicle, when the behavior of the vehicle is estimated to become unstable.