Steering assistance system, steering control device, and steering control method

One or more non-transitory computer-readable media storing computer-readable instructions that when executed by one or more processors cause the one or more processors to perform operations, the operations comprising:

• calculating a target rack stroke, which is a rack stroke of a rack bar required for generating a steering assistance force, based on steering information input by a driver;
• calculating a target command current according to the target rack stroke;
• recognizing whether an other steering control device fails;
• calculating a first command current if the other steering control device fails and calculating a second command current smaller than the first command current if the other steering control device does not fail;
• if the other steering control device does not fail, applying the second command current smaller than the first command current to the steering motor;
• if the other steering control device fails and the target rack stroke is less than or identical to a reference rack stroke, continuously and constantly applying the first command current to the steering motor;
• and
• if the other steering control device fails and the target rack stroke is larger than the reference rack stroke, periodically applying the first command current to the steering motor based on a preset input cycle.

A steering assist system, comprising:

• a steering angle sensor detecting a steering angle by rotation of a steering wheel, and generating and outputting steering information about the steering angle;
• a steering motor including a first winding motor and a second winding motor;
• a first steering control device electrically connected with the first winding motor;
• and
• a second steering control device electrically connected with the second winding motor and electrically connected with the first steering control device configured to communicate with the first steering control device,
• wherein the first steering control device is configured to:
• calculate a target rack stroke, which is a rack stroke of a rack bar required for generating a steering assistance force, and a target command current corresponding to the target rack stroke based on the steering information,
• recognize whether the second steering control device fails,
• if the second steering control device does not fail, calculate a second command current corresponding to half of the target command current and apply the second command current to the steering motor, and
• if the second steering control device fails and the target rack stroke is less than or identical to a reference rack stroke, continuously and constantly apply the first command current, identical to the target command current, to the steering motor;
• and
• if the second steering control device fails and the target rack stroke is larger than the reference rack stroke, periodically apply the first command current, identical to the target command current, to the steering motor based on a preset input cycle.