Driver assistance device

1. A driver assistance device configured to perform, when a deceleration target is detected in front of a host vehicle, deceleration assistance of the host vehicle for the deceleration target, the driver assistance device comprising:

a type determination unit configured to determine whether a type of the deceleration target is included in a category of a position-fixed object or a category of a moving object;

a loss determination unit configured to determine whether the deceleration target is lost while the deceleration assistance is being performed;

a driver assistance unit configured to continue the deceleration assistance on assumption that the lost deceleration target exists when the loss determination unit determines that the deceleration target is lost; and

a notification unit configured to

notify a driver of the host vehicle that the deceleration target is lost, when the loss determination unit determines that the deceleration target is lost and the type of the deceleration target is included in the category of the moving object, and

not notify the driver, that the deceleration target is lost, when the loss determination unit determines that the deceleration target is lost and the type of the deceleration target is included in the category of the position-fixed object.

2. The driver assistance device according to claim 1 , wherein:

the driver assistance unit is configured to continue the deceleration assistance by using a position of the deceleration target, when the loss determination unit determines that the deceleration target is lost and the type of the deceleration target is included in the category of the position-fixed object; and

the position of the deceleration target is a position when the deceleration target is lost.

3. The driver assistance device according to claim 1 , wherein:

the type determination unit is configured to determine whether the deceleration target is a traffic light and determine a lighting state of the traffic light when the deceleration target is the traffic light; and

the notification unit is configured to

determine whether a target vehicle speed of the deceleration assistance is changed to a small value by the lighting state of the traffic light changed from the lighting state at time that the traffic light is lost, when the type determination unit determines that the deceleration target is the traffic light and the loss determination unit determines that the traffic light is lost,

notify the driver that the traffic light is lost, when the change in the lighting state of the traffic light causes the target vehicle speed of the deceleration assistance to be changed to a small value, and

not notify the driver that the traffic light is lost, when the change in the lighting state of the traffic light does not cause the target vehicle speed of the deceleration assistance to be changed to a small value.

4. A driver assistance device comprising an electronic control unit configured to:

perform, when a deceleration target is detected in front of a host vehicle, a deceleration assistance of the host vehicle for the deceleration target;

determine whether a type of the deceleration target is included in a category of a position-fixed object or a category of a moving object;

determine whether the deceleration target is lost while the deceleration assistance is being performed;

continue the deceleration assistance on assumption that the lost deceleration target exists when the deceleration target is determined to be lost;

notify a driver of the host vehicle that the deceleration target is lost, when the deceleration target is determined to be lost and the type of the deceleration target is included in the category of the moving object; and

not notify the driver that the deceleration target is lost, when the deceleration target is determined to be lost and the type of the deceleration target is included in the category of the position-fixed object.

5. The driver assistance device according to claim 4 , wherein:

the electronic control unit is configured to continue the deceleration assistance by using a position of the deceleration target, when the deceleration target is determined to be lost and the type of the deceleration target is included in the category of the position-fixed object; and

the position of the deceleration target is a position when the deceleration target is lost.

6. The driver assistance device according to claim 4 , wherein the electronic control unit is configured to:

determine whether the deceleration target is a traffic light and determine a lighting state of the traffic light when the deceleration target is the traffic light;

determine whether a target vehicle speed of the deceleration assistance is changed to a small value by the lighting state of the traffic light changed from the lighting state at time that the traffic light is lost, when the deceleration target is determined to be the traffic light and the traffic light is determined to be lost;

notify the driver that the traffic light is lost, when the change in the lighting state of the traffic light causes the target vehicle speed of the deceleration assistance to be changed to a small value; and

not notify the driver that the traffic light is lost, when the change in the lighting state of the traffic light does not cause the target vehicle speed of the deceleration assistance to be changed to a small value.