Steering control apparatus

1 . A steering control apparatus to control a steering system, the steering system includes a steering shaft, a turned wheel of a vehicle, the turned wheel being turned along with rotation of the steering shaft, and a motor that rotates the steering shaft; and

the steering control apparatus comprising a processing unit configured to execute;

a target steering angle variable acquiring processing of acquiring a value of a target steering angle variable, the target steering angle variable being a variable indicating a target value of a turning angle of the turned wheel;

a target steering angle correcting processing of correcting the value of the target steering angle variable by a play compensation amount according to a steering direction, the steering direction being a direction in which the value of the target steering angle variable changes;

a gradually changing processing of gradually changing a magnitude of the play compensation amount, the play compensation amount being set for correcting the value of the target steering angle variable along with a change of the steering direction; and

a steering angle control processing of operating the motor through control with a steering angle according to a rotation angle of the steering shaft being as a control amount and with the value of the target steering angle variable being as a target value of the control amount.

2 . The steering control apparatus according to claim 1 , wherein

the gradually changing processing includes processing of defining a changing speed of the magnitude of the play compensation amount in accordance with a magnitude of a changing speed of the value of the target steering angle variable, and the changing speed of the magnitude of the play compensation amount in a case where the magnitude of the changing speed of the value of the target steering angle variable is large is set to be not less than the changing speed of the magnitude of the play compensation amount in a case where the magnitude of the changing speed of the value of the target steering angle variable is small.

3 . The steering control apparatus according to claim 1 , wherein

the gradually changing processing includes processing of gradually increasing a changing speed of the magnitude of the play compensation amount along with the change of the steering direction.

4 . The steering control apparatus according to claim 1 , wherein:

the processing unit is configured to perform the steering angle control processing in an autonomous steering mode, and is configured to perform play displacement calculating processing and basic amount setting processing;

the play displacement calculating processing is processing of calculating a play displacement in accordance with each change of the steering angle, and the play displacement is an amount for specifying a position in a region where the turning angle does not change with respect to the change of the steering angle;

the basic amount setting processing is processing of setting a basic amount of play according to a right steering direction and a basic amount of play according to a left steering direction to amounts for setting the steering angle to a value of an end part of the region, in accordance with the play displacement at a time point of entering the autonomous steering mode; and

the gradually changing processing is processing of gradually changing the play compensation amount to the basic amount of play.