Steering system

• US 7,954,827 B2
• Filed: 02/08/2008
• Issued: 06/07/2011
• Est. Priority Date: 02/16/2007
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Terada, Yasuhiro, Maruyama, Kouhei, Horiuchi, Yutaka, Yanagi, Takashi, Sugitani, Nobuo
• Primary Examiner(s): Silbermann; Joanne
• Assistant Examiner(s): YEAGLEY, DANIEL S
• Application Number:
  US12/028,279
• Publication Number:
  US 20080196966A1
• Time in Patent Office: 1,215 Days
• Field of Search: 180/446, 701/41, 701/48, 280/5.5, 280/5.51, 280/5.52, 280/5.522
• US Class Current: 280/5.522
• CPC Class Codes: B62D 17/00 Means on vehicles for adjusting camber, castor, or toe-in
• CPC Class Codes: B62D 5/0481 monitoring the steering system, e.g. failures
• CPC Class Codes: B62D 7/146 characterised by comprising means for steering by acting on the suspension system, e.g. on the mountings of the suspension arms

Abstract

A steering controller for an electric power steering device 110 includes a base signal computing part 51 for computing a base signal D_T in accordance with at least the steering torque; a damper compensation signal computing part 52 for computing a damper compensation signal in accordance with an angular velocity of an electric motor 4 or a speed of steering wheel turn; and an inertia compensation signal computing part 53 for compensating inertia and viscosity in the steering unit. The electric motor is driven by a target signal IM₁ obtained by compensating the base signal with a damper compensation signal and an inertia compensation signal, to provide a steering auxiliary force. The target signal of the auxiliary torque is compensated so that a difference between a reference self-aligning torque of front wheel in a front wheel steering vehicle and a self-aligning torque of front wheel in an all-wheel steering vehicle is provided to a driver as a responsive feeling from the steering torque.

Claims

1. A steering system comprising:

an electric power steering device which comprises a steering unit of front wheels having an electric motor configured to generate an auxiliary torque in accordance with at least a steering torque, and is configured to transmit the auxiliary torque to the steering unit;

toe angle changers capable of changing toe angles of respective right and left rear wheels in accordance with at least a turning angle of the front wheels and a vehicle speed; and

a steering controller configured to control the electric power steering device and the toe angle changer,

the steering controller comprising;

an auxiliary torque calculating unit configured to calculate a target value of the auxiliary torque and to output a target signal for driving the electric motor, in which a difference between a first self-aligning torque generated at the front wheels and a second self-aligning torque generated at front wheels of a hypothetical vehicle having only a front wheel steering function is compensated, wherein the steering controller further comprises an anomaly detection unit configured to detect an abnormal state of the toe angle changer, the auxiliary torque calculating unit comprises a first table for calculating the auxiliary torque in a case where the toe angle changer is in a normal state, and a second table for calculating the auxiliary torque in a case where the toe angle changer is in an abnormal state, and when the anomaly detection unit detects an abnormal state of the toe angle changer, the auxiliary torque calculating unit switches form the first table to the second table and calculates the target value which makes a responsive feeling from the steering torque larger.

2. The steering system according to claim 1, wherein

the steering controller further comprises

a restoring torque calculating unit configured to calculate the first self-aligning torque based on at least a yaw rate, speed and slip angle of the vehicle and the turning angle of the front wheels,

a reference restoring torque calculating unit configured to calculate the second self-aligning torque based on at least the vehicle speed and the turning angle of the front wheels, and

a difference compensation unit configured to calculate a difference between the first self-aligning torque and the second self-aligning torque and to compensate the target signal with the difference.

3. A steering system comprising:

an electric power steering device which comprises a steering unit of front wheels having an electric motor configured to generate an auxiliary torque in accordance with at least a steering torque, and is configured to transmit the auxiliary torque to the steering unit;

toe angle changers capable of changing toe angles of respective right and left rear wheels in accordance with at least a turning angle of the front wheels and a vehicle speed; and

a steering controller configured to control the electric power steering device and the toe angle changer,

the steering controller comprising;

an auxiliary torque calculating unit configured to calculate a target value of the auxiliary torque, and

an anomaly detection unit configured to detect an abnormal state of the toe angle changer,

the auxiliary torque calculating unit comprising

a first table for calculating the auxiliary torque in a case where the toe angle changer is in a normal sate, and a second table for calculating the auxiliary torque in a case where the toe angle changer is in an abnormal state,

wherein, when the anomaly detection unit detects an abnormal state of the toe angle changer, the auxiliary torque calculating unit switches from the first table to the second table and calculates the target value which makes a responsive feeling from the steering torque larger.