Steering control device

A steering control device that controls a steering system including a housing, a turning shaft which is accommodated in the housing to reciprocate, and an actuator which applies a motor torque for turning wheels connected the turning shaft using a motor as a drive source, the steering control device comprising:

• an electronic control unit,
• wherein the electronic control unit is configured to:
• detect an absolute steering angle which is a rotation angle of a rotation shaft which is able to be converted into a turning angle of the turning wheels and which is expressed as an absolute angle including a range greater than 360°;
• calculate a current command value corresponding to a target value of the motor torque which is output from the motor;
• control driving of the motor such that an actual current value which is supplied to the motor reaches the current command value;
• store an end-position-corresponding angle which is an angle indicating an end position at which movement of the turning shaft is regulated by an end contact of the turning shaft coming into contact with the housing and which is correlated with the absolute steering angle;
• perform end contact relaxation control for correcting the current command value such that a decrease of an end separation angle indicating a distance of the absolute steering angle from the end-position-corresponding angle is regulated when the end separation angle is equal to or less than a predetermined angle;
• calculate the current command value such that an increase of the end separation angle is not regulated by the end contact relaxation control when the end separation angle is equal to or less than the predetermined angle,
• calculate a steering angle limit value which decreases based on a decrease of the end separation angle when the end separation angle is equal to or less than the predetermined angle;
• perform the end contact relaxation control by limiting the absolute value of the current command value to the steering angle limit value;
• calculate an angle limiting component which increases based on the decrease of the end separation angle when the end separation angle is equal to or less than the predetermined angle;
• calculate the steering angle limit value based on a pre-adjustment steering angle limit value which is obtained by subtracting the angle limiting component from a rated current of the motor;
• and
• set the absolute value of the steering angle limit value to the rated current when the end separation angle is equal to or less than the predetermined angle and the end separation angle increases.