Apparatus and method of controlling electric power steering apparatus

• US 4,946,001 A
• Filed: 03/08/1989
• Issued: 08/07/1990
• Est. Priority Date: 04/30/1988
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited, Unisia JKC Steering Systems Company Limited (Hitachi, Ltd.)
• Original Assignee: Fujitsu Limited, Jidosha Kiki Co., Ltd.
• Inventors: Watanabe, Masaki, Taniguchi, Yoshiaki, Iizawa, Ryuji
• Primary Examiner(s): HILL, MITCHELL
• Application Number:
  US07/321,628
• Time in Patent Office: 517 Days
• Field of Search: 180/79.1, 180/140, 280/91, 364/424.05
• US Class Current: 180/446
• CPC Class Codes: B62D 5/0466 for returning the steering wheel to neutral position

Abstract

In a control method and apparatus of an electric power steering apparatus of this invention, a reverse torque R against a steering torque and a torque produced by the motor are detected, and a target value T_DT which is set based on the reverse torque and is used when the torque produced by the motor is controlled has a range given by T_DT ×R>R².

Claims

1. An electric power steering apparatus for assisting a steering torque with a motor output torque, comprising:

detection means for detecting a reverse torque R against the steering torque and the motor output torque;

target value setting means for setting a target value T_DT, of a parameter for determining a steering operation based on the detected reverse torque R; and

control means for controlling the motor output torque based upon the detected reverse torque R and the target value T_DT whereby T_DT ×

R>

R².

2. An apparatus according to claim 1, wherein the steering torque is detected by a torque sensor connected to a steering unit.

3. An apparatus according to claim 1, wherein the reverse torque R is obtained by an R calculator for calculating the reverse torque based on the steering torque, the motor output torque, a pinion angular velocity, and a pinion angular acceleration.

4. A control method of an electric power steering apparatus, comprising the steps of:

detecting a reverse torque R against a steering torque obtained by a steering operation and an output torque from a motor for assisting the steering torque;

setting a target value TDT of a parameter for determining a steering operation based on the detected reverse torque R; and

controlling the motor output torque based upon the detected reverse torque R and the target value TDT whereby T_DT ×

R>

R².

5. A method according to claim 4, wherein the reverse torque R is obtained by an R calculator for calculating the reverse torque based on the steering torque, the motor output torque, a pinion angular velocity, and a pinion angular acceleration.