Steering control device, steering control method, and computer program product

A steering control method for a vehicle for controlling and linking a movement of a steering member by a steering actuator with a movement of a turning tire by a turning actuator, the steering control method comprising:

• controlling an actual steering angle of the steering member by controlling a steering output torque output from the steering actuator;
• and
• controlling an actual turning angle of the turning tire by controlling a turning output torque output from the turning actuator, wherein
• in the controlling the actual turning angle, a gradual reduction control is performed to gradually decrease the turning output torque during a linked control in which the actual steering angle is controlled in conjunction with the actual turning angle in response to a stop instruction of the vehicle,
• in the controlling the actual turning angle, an energization to the turning actuator is cut after the gradual reduction control of the turning output torque, and
• in the controlling the actual steering angle, an energization to the steering actuator is cut after the gradual reduction control of the turning output torque,
• wherein
• in the controlling the actual turning angle, the gradual reduction control of the turning output torque is performed by gradually decreasing a current applied to the turning actuator, and
• in the controlling the actual turning angle, the current applied to the turning actuator is gradually decreased by a low-pass filter whose cutoff frequency is lower than a resonance frequency of a turning system that includes the turning tire of the vehicle.

A non-transitory computer readable storage medium storing a computer program product for a vehicle for controlling and linking a movement of a steering member by a steering actuator with a movement of a turning tire by a turning actuator, the computer program product comprising instructions configured to, when executed by at least one processor, cause the at least one processor to:

• control an actual steering angle of the steering member by controlling a steering output torque output from the steering actuator;
• and
• control an actual turning angle of the turning tire by controlling a turning output torque output from the turning actuator, wherein
• in the controlling the actual turning angle, a gradual reduction control is performed to gradually decrease the turning output torque during a linked control in which the actual steering angle is controlled in conjunction with the actual turning angle in response to a stop instruction of the vehicle,
• in the controlling the actual turning angle, an energization to the turning actuator is cut after the gradual reduction control of the turning output torque, and
• in the controlling the actual steering angle, an energization to the steering actuator is cut after the gradual reduction control of the turning output torque, wherein
• the gradual reduction control of the turning output torque is performed by gradually decreasing a current applied to the turning actuator, and
• the current applied to the turning actuator is gradually decreased by a low-pass filter whose cutoff frequency is lower than a resonance frequency of a turning system that includes the turning tire of the vehicle.