Recognition-error detector and electric-brake controller

Patent metadata

Field	Value
Publication number	US-2019351884-A1
Application number	US-201916402379-A
Country	US
Kind code	A1
Filing date	May 3, 2019
Priority date	May 17, 2018
Publication date	Nov 21, 2019
Grant date	—

Abstract

An electric-brake controller controls an electric brake operable by an electric motor. The electric-brake controller includes: a rotation-angle obtainer including (i) a relative-rotation-angle obtaining unit that obtains a relative rotation angle of the electric motor for a set time, based on values output and received from a rotation-angle sensor at intervals of the set time, and (ii) an absolute-rotation-angle obtaining unit that calculates the obtained relative rotation angle with consideration of an orientation of the relative rotation angle to obtain an absolute rotation angle that is a rotation angle of the electric motor from a start of its operation; a recognition-error detector that detects a recognition error in the rotation-angle obtainer based on the obtained absolute rotation angle or a changing state of the absolute rotation angle; and a motor controller that controls the electric motor based on a result of detection performed by the recognition-error detector.

First claim

What is claimed is:

1 . An electric-brake controller configured to control an electric brake that is provided for a wheel of a vehicle and operable by an electric motor to reduce rotation of the wheel by pressing a pressing member via a friction member against a brake rotor rotating with the wheel,
wherein the electric-brake controller comprises:
a rotation-angle obtainer comprising (i) a relative-rotation-angle obtaining unit configured to obtain a relative rotation angle based on values output and received from a rotation-angle sensor at intervals of a set length of time, the relative rotation angle being a rotation angle of the electric motor for the set length of time, and (i) an absolute-rotation-angle obtaining unit configured to calculate the relative rotation angle obtained by the relative-rotation-angle obtaining unit, with consideration of an orientation of the relative rotation angle to obtain an absolute rotation angle that is a rotation angle of the electric motor from a start of operation of the electric motor;
a recognition-error detector configured to detect a recognition error in the rotation-angle obtainer based on one of the absolute rotation angle obtained by the absolute-rotation-angle obtaining unit and a changing state of the absolute rotation angle; and
a motor controller configured to control the electric motor based on a result of detection performed by the recognition-error detector.

2 . The electric-brake controller according to claim 1 , wherein the motor controller is configured to control the electric motor based on a position of the pressing member which is obtained based on the absolute rotation angle obtained by the absolute-rotation-angle obtaining unit.

3 . The electric-brake controller according to claim 1 , wherein the recognition-error detector is configured to, when a change pattern as the changing state of a set number of the absolute rotation angles obtained successively by the absolute-rotation-angle obtaining unit is identical to one of a plurality of error patterns set in advance, detect that at least one of the set number of the absolute rotation angles is obtained by the rotation-angle obtainer based on a value with the recognition error.

4 . The electric-brake controller according to claim 3 , wherein the plurality of error patterns comprise:
a first error pattern comprising a pattern in which the absolute rotation angle increases, thereafter decreases twice successively, and thereafter increases; and a second error pattern comprising a pattern in which the absolute rotation angle decreases, increases twice successively, and thereafter decreases.

5 . The electric-brake controller according to claim 3 ,
wherein the absolute rotation angle is an angle that increases with rotation of the electric motor in a forward direction and decreases with rotation of the electric motor in a reverse direction, and wherein the plurality of error patterns comprise;
a third error pattern comprising a pattern in which the absolute rotation angle decreases twice successively and thereafter increases with rotation of the electric motor in the forward direction; and
a fourth error pattern comprising a pattern in which the absolute rotation angle increases twice successively and thereafter decreases with rotation of the electric motor in the reverse direction.

6 . The electric-brake controller according to claim 1 , wherein the recognition-error detector is configured to detect that the second absolute rotation angle and the third absolute rotation angle are obtained by the rotation-angle obtainer based on a value with the recognition error, when, among at least four absolute rotation angles each as the absolute rotation angle which are obtained successively by the absolute-rotation-angle obtaining unit, an absolute value of a difference between (a) an average changed angle between a second absolute rotation angle and a fourth absolute rotation angle and (b) an average changed angle between a first absolute rotation angle and a modified absolute rotation angle that is a third absolute rotation angle obtained by excluding the second absolute rotation angle is greater than a first threshold value.

7 . The electric-brake controller according to claim 1 , wherein the recognition-error detector is configured to detect that the second absolute rotation angle and. the third absolute rotation angle are obtained by the rotation-angle obtainer based on a value with the recognition error, when, among at least three absolute rotation angles each as the absolute rotation angle which are obtained successively by the absolute-rotation-angle obtaining unit, an absolute value of a difference between an actual absolute rotation angle as a third absolute rotation angle and a modified absolute rotation angle as a third absolute rotation angle obtained by excluding the second absolute rotation angle is greater than a second threshold value.

8 . The electric-brake controller according to claim 1 ,
wherein the rotation-angle sensor is configured to detect a rotation angle of the electric motor as a value between 0 and 360 degrees and output an output value representing the rotation angle, wherein the relative-rotation-angle obtaining unit is configured to, in a case where an absolute value of a value obtained by subtracting a previous value of the received value from a present value of the received value is less than or equal to 180 degrees:
obtain that the orientation of the relative rotation angle is a positive orientation, when the obtained value is a positive value; and
obtain that the orientation of the relative rotation angle is a negative orientation, when the obtained value is a negative value, and
wherein the relative-rotation-angle obtaining unit is configured to, in a case where the absolute value of the obtained value is greater than 180 degrees;
obtain that the orientation of the relative rotation angle is a negative orientation, when the obtained value is a positive value; and
obtain that the orientation of the relative rotation angle is a positive orientation, when the obtained value is a negative value.

9 . The electric-brake controller according to claim 1 ,
wherein the absolute-rotation-angle obtaining unit comprises:
a first absolute-rotation-angle obtaining unit configured to, when the recognition error is detected by the recognition-error detector, obtain the absolute rotation angle based on a modified change pattern as a change pattern comprising a modified absolute rotation angle that is one of a plurality of the absolute rotation angles which is obtained by excluding the absolute rotation angle obtained based on a value with the recognition error; and
a second absolute-rotation-angle obtaining unit configured to obtain the absolute rotation angle based an actual change pattern of the plurality of the absolute rotation angles, and
wherein the motor controller comprises a recognition-error-detected-situation motor controller configured to control the electric motor based on a position located at a rear of (i) a first position of the pressing member which is determined based on the absolute rotation angle obtained by the first absolute-rotation-angle obtaining unit, and (ii) a second position of the pressing member which is determined based on the absolute rotation angle obtained by the second absolute-rotation-angle obtaining unit.

10 . The electric-brake controller according to claim 9 , wherein the recognition-error-detected-situation motor controller comprises a recognition-error-detected-situation returner configured to, when the electric brake is switched from an operating state to a non-operating state, move the pressing member back to an initial pos

Assignees

• Toyota Motor Co Ltd

Inventors

• Tajima Yasuhiro
• Mima Hiroki
• Takahashi Akihiro

Classifications

• B60T17/22

  Devices for monitoring or checking brake systems; Signal devices · CPC title

• B60T13/74

  with electrical assistance or drive · CPC title

• B60T8/4081

  Systems with stroke simulating devices for driver input (B60T8/4077 takes precedence) · CPC title

• B60T8/3255

  Systems in which the braking action is dependent on brake pedal data · CPC title

• B60T8/267

  for hybrid systems with different kind of brakes on different axles · CPC title