Control apparatus for vehicle-mounted apparatus and power steering apparatus

• US 10,166,977 B2
• Filed: 08/06/2015
• Issued: 01/01/2019
• Est. Priority Date: 09/24/2014
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: Sasaki, Mitsuo, Hisazumi, Takumi
• Primary Examiner(s): To, Tuan C
• Application Number:
  US15/503,466
• Publication Number:
  US 20170240168A1
• Time in Patent Office: 1,244 Days
• Field of Search: 701 41
• CPC Class Codes: B60T 11/21 with two pedals operating on respective circuits, pressures therein being equalised when both pedals are operated together, e.g. for steering steering non-deflectable wheels or endless tracks by differentially driving ground-engaging elements on opposite vehicle sides using brakes as main steering effecting means B62D11/08
• CPC Class Codes: B60T 7/12 for automatic initiation; for initiation not subject to will of driver or passenger limiting speed of vehicles other than rail vehicles B60K31/00
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 10/22 including control of suspension systems
• CPC Class Codes: B60W 2510/202 Steering torque
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: B60W 2710/18 Braking system
• CPC Class Codes: B60W 2710/20 Steering systems
• CPC Class Codes: B60W 2710/202 Steering torque
• CPC Class Codes: B60W 2710/22 Suspension systems
• CPC Class Codes: B60W 30/025 related to comfort of drivers or passengers
• CPC Class Codes: B60W 30/045 Improving turning performance
• CPC Class Codes: B62D 15/0235 by measuring or deriving directly at the electric power steering motor
• CPC Class Codes: B62D 5/0409 Electric motor acting on the steering column
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: B62D 5/049 detecting sensor failures
• CPC Class Codes: B62D 6/10 characterised by means for sensing or determining torque

Abstract

One aspect of the present invention increases or reduces an amplitude or amplitudes of a steering angle sensor output signal and/or a motor rotational angle signal, and outputs a motor instruction signal based on a substitute signal for a torque sensor output signal that is calculated based on at least one of the steering angle sensor output signal and the motor rotational angle signal that is subjected to the adjustment of the amplitude thereof, and the other of the steering angle sensor output signal and the motor rotational angle signal, when an abnormality is detected in the torque sensor output signal.

Claims

1. A power steering apparatus comprising:

a steering mechanism configured to turn a turning target wheel according to a steering operation performed on a steering wheel;

a torque sensor provided at the steering mechanism and including a torsion bar, the torque sensor being configured to detect a steering torque generated at the steering mechanism based on a torsional amount of the torsion bar;

a steering angle sensor provided on the steering wheel side of the steering mechanism with respect to the torsion bar, the steering angle sensor being configured to detect a steering angle that is a steering amount of the steering wheel;

an electric motor provided on the turning target wheel side of the steering mechanism with respect to the torsion bar, the electric motor being configured to provide a steering force to the steering mechanism;

an electronic control unit configured to control driving of the electric motor;

a motor rotational angle sensor provided at the electric motor and configured to detect a rotational angle of a rotor of the electric motor;

a torque signal reception portion provided at the electronic control unit and configured to receive a torque sensor output signal, which is a detection signal output from the torque sensor;

a steering signal reception portion provided at the electronic control unit and configured to receive a steering angle sensor output signal, which is a detection signal output from the steering angle sensor, according to a first sampling cycle;

a motor rotational angle signal reception portion provided at the electronic control unit and configured to receive a motor rotational angle signal, which is a detection signal output from the motor rotational angle sensor, according to a second sampling cycle different from the first sampling cycle;

an abnormality detection circuit provided at the electronic control unit and configured to detect an abnormality in the torque sensor output signal;

an amplitude adjustment circuit provided at the electronic control unit and configured to increase or reduce an amplitude or amplitudes of the steering angle sensor output signal and/or the motor rotational angle signal;

a substitute signal calculation circuit provided at the electronic control unit and configured to calculate a substitute signal for the torque sensor output signal based on at least one of the steering angle sensor output signal and the motor rotational angle signal that is subjected to the adjustment of the amplitude thereof by the amplitude adjustment circuit, and the other of these signals; and

a motor control circuit provided at the electronic control unit and configured to output a motor instruction signal for driving the electric motor based on the torque sensor output signal at normal times when no abnormality is detected in the torque sensor output signal by the abnormality detection circuit, and also output the motor instruction signal based on the substitute signal when an abnormality is detected in the torque sensor output signal by the abnormality detection circuit.

2. The power steering apparatus according to claim 1, wherein the sampling cycle of the steering angle sensor output signal is longer than the sampling cycle of the motor rotational angle signal, and

wherein the amplitude adjustment circuit increases the amplitude of the steering angle sensor output signal.

3. The power steering apparatus according to claim 2, wherein the steering angle sensor includes a combination of a plurality of gears, and

wherein the power steering apparatus further comprises a smoothing circuit configured to smooth the steering angle sensor output signal.

4. The power steering apparatus according to claim 2, further comprising an amplitude readjustment circuit,

wherein the amplitude readjustment circuit reduces an amplitude of a signal acquired as a difference after the difference between the signal subjected to the adjustment of the amplitude thereof by the amplitude adjustment circuit and the other signal is calculated.

5. The power steering apparatus according to claim 1, further comprising a speed reducer provided between the steering mechanism and the electric motor, the speed reducer including a ball screw mechanism configured to transmit a rotational force of the electric motor to the steering mechanism.

6. The power steering apparatus according to claim 1, wherein the steering angle sensor output signal and the motor rotational angle signal have different sampling cycles from each other.

7. The power steering apparatus according to claim 6, further comprising a smoothing circuit provided at the electronic control unit and configured to smooth a signal corresponding to longer one of the first sampling cycle and the second sampling cycle,

wherein the substitute signal calculation circuit calculates the substitute signal based on the signal smoothed by the smoothing circuit.