Automatic steering system and automatic steering method

An automatic steering method to execute automatic steering control of a vehicle by a controller,

• wherein the vehicle comprises a detection device which is configured to detect driving environment information of the vehicle,
• wherein the detection device includes:
• an acceleration sensor which is configured to detect lateral acceleration of the vehicle;
• a vehicle speed sensor which is configured to detect driving speed of the vehicle;
• and
• a yaw rate sensor is configured to detect yaw rate of the vehicle,
• wherein the method comprising the steps of:
• executing target steering angle calculation processing to calculate a target steering angle in the automatic steering control based on the driving environment information;
• and
• calculating a learning value of the lateral acceleration, wherein the learning value is calculated based on an error of a detected value of the lateral acceleration and an estimation value of the lateral acceleration calculated by using the driving speed and the yaw rate,
• wherein the step of executing the target steering angle calculation processing includes the steps of:
• judging whether or not the acceleration sensor is normal;
• if it is judged that the acceleration sensor is normal, calculating the target steering angle by using the detected value;
• and
• if it is judged that the acceleration sensor is abnormal, switching the lateral acceleration used to calculate the target steering angle from the detected value to a backup value of the lateral acceleration,
• wherein the backup value is calculated by using the estimation value and the learning value that is calculated before a timing at which the acceleration sensor is judged to abnormal.