Driving assist device and driving assist method

A driving assist method comprising:

• (a) a first step in which a control device obtains an output of a first sensor for detecting an object in front of the control device;
• (b) a second step in which the control device obtains an output of a second sensor, for detecting an object in front of the control device;
• and
• (c) a third step in which the control device executes inter-vehicle distance control using the output of the first sensor or the output of the second sensor to keep an inter-vehicle distance within a predetermined range, the inter-vehicle distance being a distance between a vehicle and at least one preceding object in front of the vehicle;
• wherein
• the control device fails to execute the inter-vehicle distance control under a predetermined first condition upon determination that
• the at least one preceding object is detected based on the output of one of the first sensor and the second sensor without being detected based on the output of the other of the first and second sensors;
• and
• an environment of a non-detection sensor that is the other of the first and second sensors satisfies a first requirement for determination of a reliability of the output of the non-detection sensor;
• and
• the control device executes the inter-vehicle distance control under a predetermined second condition upon determination that the environment of the non-detection sensor satisfies a second requirement for determination of the reliability of the output of the non-detection sensor, each of the first and second conditions representing that a corresponding level of the reliability of the output of the non-detection sensor, the level of the reliability of the output of the non-detection sensor represented by the second condition being lower than the level of the reliability of the output of the non-detection sensor represented by the first condition.