Electric power steering control device

Abstract

An electric power steering control device comprises a motor to apply an assist torque to a steering device, a torque detector to detect a steering torque applied by a driver, a setting mechanism to set a motor torque to be outputted to the motor based on the steering torque detected by the torque detector, a rotational angle detector to detect a rotational angle of the motor, a filter processor to output a vibration-suppression gain for suppressing a vibration due to a tire rotation by performing a filter processing on the rotational angle detected by the rotational angle detector, and a correcting mechanism to correct the motor torque set by the setting mechanism by using the vibration-suppression gain outputted by the filter processor so as to suppress the vibration due to the tire rotation, wherein the filter processor is configured to include a vibration extracting filter which has a frequency characteristic that a gain becomes a specified magnitude (value) at a cut-off angle frequency and a phase advances by 90 degrees at the cut-off angle frequency and to vary the cut-off angle frequency of the vibration extracting filter in accordance with a tire rotation frequency which is changeable according to a vehicle speed.

Description

technical field [0001] The present invention relates to a control device of an electric power steering device mounted in a vehicle such as an automobile. Background technique [0002] Electric power steering devices are installed in various vehicles. The electric power steering device includes a motor that applies assist torque to the steering device, a torque sensor that detects a driver's steering torque, a vehicle speed sensor that detects a vehicle speed, and a control unit (ECU: Electronic Control Unit). The ECU sets the torque to be output by the motor (motor torque) based on the steering torque detected by the torque sensor and the vehicle speed detected by the vehicle speed sensor. The ECU controls the current applied to the motor (ie, assist control) to achieve a set motor torque. [0003] A conventional ECU performs vibration suppression control for suppressing vibration caused by disturbances (such as resonance) in parallel in addition to the above-mentioned boo...

AI Technical Summary

Problems solved by technology

In addition, the shimmy frequency is also affected by factors such as changes over time in the suspension of each vehicle.

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