Electric power steering controller

摘要

An electric power steering controller adjustably generates a target steer torque dynamically by weighting (i) a load based target steer torque that is determined based on an estimated load and (ii) a steer angle based target steer torque with a weighting ratio. The weighting ratio varies depending on a condition of a road surface on which a subject vehicle is traveling, a steering state of the driver and the like, which enables an adjustment of the target steer torque to suitably accommodate the condition of the road surface and to provide a road surface conscious steering feel while achieving robustness over an influence of a friction of the mechanical components in a steering system.

主权项

1. An electric power steering controller disposed in an electric power steering system having a motor generating an assist torque that assists a steering operation of a steering member that is operated by a driver of a subject vehicle; a torque detector detecting a steer torque that is applied to the steering member; and a steer angle detector detecting a steer angle of a rotation member that rotates according to the steering operation of the steering member, the controller comprising:
an Electronic Power Steering Electronic Control Unit (EPSECU), the EPSECU configured to include:
a load estimator estimating an estimated load based on a torque that is applied to a steering mechanism for a driver-desired steering of a subject vehicle;a load based target determiner generating a first target steer torque as a load based target steer torque based on the estimated load estimated by the load estimator;a steer angle based target determiner generating a second target steer torque as a steer angle based target steer torque based on the steer angle detected by the steer angle detector;a target steer torque generator generating a target steer torque as a target value of the steer torque based on the load based target steer torque and the steer angle based target steer torque; anda motor controller section controlling the motor to output the steer torque from the motor according to the target steer torque, wherein the target steer torque generator includes a weighting ratio determiner determining a weighting ratio according to a steering system state indicator value that is determined based on at least one of the steer amount of the steering member by the driver and the estimated load, and the target steer torque generator generates the target steer torque by performing a weighted addition of the load based target steer torque and the steer angle based target steer torque.