Electric power steering apparatus

• US 6,470,994 B1
• Filed: 09/02/1998
• Issued: 10/29/2002
• Est. Priority Date: 09/03/1997
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Shimizu, Yasuo, Takimoto, Shigenori
• Primary Examiner(s): Olszewski, Robert P.
• Assistant Examiner(s): Fischer, Andrew J.
• Application Number:
  US09/145,473
• Time in Patent Office: 1,518 Days
• Field of Search: 180/446, 180/443, 180/444, 701/41, 701/42
• US Class Current: 180/446
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

An electric power steering apparatus having a variable ratio steering gear mechanism includes an electric motor for applying a steering assist torque to the steering system of a vehicle, a control unit for controlling operation of the electric motor on the basis of at least a steering torque of the steering system, and a motor drive unit for driving the motor on the basis of an output signal from the control unit. The control unit includes a steering torque calculating part for outputting a steering torque component corresponding to the steering torque, and a vehicle behavior calculating part for outputting a behavior component corresponding to a vehicle behavior. The control unit corrects the steering torque component by damping it with the behavior component.

Claims

1. An electric power steering apparatus for a vehicle including a variable ratio steering gear mechanism, comprising:

an electric motor applying a steering assist torque to a steering system of the vehicle;

a steering torque sensor detecting a steering torque of said steering system and generating a steering torque signal corresponding to the detected steering torque;

a behavior sensor detecting a yaw angular velocity of the vehicle and generating a yaw rate signal corresponding to the detected vehicle yaw rate;

a control unit controlling operation of said electric motor on the basis of at least the steering torque, said control unit including

a steering torque calculating part outputting a steering torque component corresponding to the steering torque signal output from said steering torque sensor, and

a vehicle behavior calculating part outputting a yaw rate component corresponding to the yaw rate signal output from said behavior sensor,

said control unit correcting said steering torque component by damping it with said yaw rate component including subtracting a first value based on said yaw rate component from said steering torque component thereby suppressing oversteer when the steering system is in a forward state;

a motor drive unit driving said motor on the basis of an output signal from said control unit;

a vehicle velocity sensor detecting a velocity of the vehicle and generating a vehicle velocity signal corresponding to the detected velocity of the vehicle,

wherein said control unit further includes;

a vehicle velocity calculating part outputting a vehicle velocity component corresponding to the vehicle velocity signal output from said vehicle velocity sensor, and

a steering condition detecting section detecting a forward state and a return state of the steering system, and

wherein said control unit corrects said steering torque component by subtracting from said steering torque component said first value determined on the basis of said yaw rate component and said vehicle velocity component when the forward state is detected by said steering condition detecting section and by adding said steering torque component and a second value determined on the basis of said yaw rate component and said vehicle velocity component when the return state is detected by said steering condition detecting section.