Jtekt Corporation

Nissan Motor Company Limited

Tetsuya Nozawa

Hirozumi Eki

Takayuki Ohta

Shinya Aono

Shigeto Matsuo

Yuuichi Fukuyama

Tomohiko Usui

Takashi Sekiguchi

The microcomputer calculates a first assist component based on a vehicle speed value and a steering torque, calculates a rotation angle command value based on at least the vehicle speed value and a first assist component, and calculates a second assist component by adjusting a rotation angle to the rotation angle command value through feedback control. The microcomputer sets a limited statewhere the second assist component is disabled when a vehicle is stationary. During an abnormality determination period during which the vehicle speed value is determined to be abnormal, the microcomputer sets the vehicle speed value to a provisional vehicle speed value. Further, in a limited statethat is set when the vehicle is stationary during the abnormality determination period, the microcomputer calculates the first assist component based on a provisional vehicle speed value, and disables the second assist component.

Steering control system

An electric power steering apparatus includes a motor for applying assist torque to a vehicle steering mechanism and a controller, which controls driving of the motor to cause the assist torque to follow an assist command value. The controller calculates a basic assist command value based on steering torque applied to the steering mechanism and corrects the basic assist command value using a correction value, thereby setting the assist command value. If the steering torque has an absolute value greater than a threshold value when the vehicle is in a straight-line traveling state, the controller sets the correction value such that the absolute value of the steering torque is reduced. If the steering torque has an absolute value less than the threshold value when the vehicle is in a straight-line traveling state, the controller sets the correction value such that the absolute value of the assist command value is reduced.

Electric power steering apparatus

A rotational angle correction controller controls generation of an inverse assist torque using the 'phase deviation' due to the correction of the rotational angle &#x3b8;, thereby performing the rotational angle correction control to smooth rotation of the motor during two phase drive. In addition, the rotational angle correction controller includes an oscillation detection part that detects the occurrence of oscillation in the steering system. When the level of the detected oscillation exceeds the predetermined level, the correction amount in the rotational angle correction control is reduced.

Electric power steering device

The rotational angle correction controller includes a second correction amount-computing part that computes a second correction amount &#x3b5;for correcting the rotational angle &#x3b8; such that the phase is shifted in the steering operation direction, and the rotational angle correction controller performs the rotational angle correction by adding the computed second correction amount &#x3b5;to the rotational angle &#x3b8;. Further, the rotational angle correction controller includes a stuck steering wheel determining part that detects the significant reduction in the follow-up performance of the motor with respect to the steering operation that occurs due to the existence of the deceleration section caused by execution of the above-described electric current restriction, that is, the occurrence of the stuck steering wheel. When the occurrence of the stuck steering wheel is detected, the second correction amount-computing part changes the second correction amount &#x3b5;to a value (&#x3b5;') larger than the normal value.

Growing community of inventors

Okazaki, Japan

Tetsuya Nozawa