Method and apparatus for determining a rotation center of a rotary body

• US 4,970,906 A
• Filed: 04/24/1990
• Issued: 11/20/1990
• Est. Priority Date: 01/14/1986
• Status: Expired due to Fees

• Current Assignee: Koito Manufacturing Company Limited
• Original Assignee: Koito Manufacturing Company Limited
• Inventors: Takahashi, Kazuki, Toda, Atsushi, Shibata, Hiroki, Wada, Kiyoshi
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US07/513,020
• Time in Patent Office: 210 Days
• Field of Search: 73/118.1, 73/865.8, 364/424, 364/559, 362/37, 362/40-60, 362/42, 377/45, 377/29, 340/52 R, 340/686, 280/771, 180/141
• US Class Current: 73/865.8
• CPC Class Codes: B60Q 1/40 having mechanical, electric or electronic automatic return to inoperative position
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00

Abstract

A method and an apparatus for determining a rotation center of a rotary body comprises a rotary body rotating in clockwise and counterclockwise directions in cooperation with the steering for a vehicle, and original position detecting circuit which detects a predetermined original angular position which the rotary body taken per each rotation, thus judging an original angular position taken when other original angular positions are not detected within a lapse of a predetermined time after the original angular position has been detected as rotation centers in the clockwise and counterclockwise directions of the rotary body.

Claims

1. A method of determining a rotational angular center of a steering wheel being rotated in a clockwise or counterclockwise direction, each revolution of said steering wheel having an original angular position wherein the original angular position for one of said revolutions is the rotational angular center to be determined, said method comprising the steps of:

(a) arranging a position sensor including a photo interrupter and a rotary disk with a slit opening, said disk rotating in cooperation with the steering wheel, said position sensor having the capability of detecting each of said original angular positions for each of said revolutions;

(b) using said position sensor for detecting said original angular position for each of said revolutions;

(c) assigning one of said detecting original angular positions to be a potential rotational angular center of said steering wheel;

(d) determining that the assigned potential rotational angular position is the rotational angular center of said steering wheel when no other original position is detected within a predetermined period of time.

2. The method defined by claim 1 wherein said position sensor includes three photo-interrupters and a rotary disk with a plurality of slit openings disposed at an equiangular distance around said disk within a first concentric ring of said disk and a single slit opening disposed within a second concentric ring of said disk such that two of said photo-interruptors are disposed adjacent to each other at a passing position of said plurality of slit openings and said third photo-interrupter is disposed at a passing position of said single slit opening, wherein when said single slit opening passes by said third photo-interrupter, said steering wheel is at one of said original angular positions.

3. The method defined by claim 2 wherein as said plurality of slit openings pass by said first and second photo-interruptors pulse signals are generated representing an amount of steering in a clockwise and counter-clockwise direction from said rotational angular center such that said amount is zero at said rotational angular center.

4. A method of determining a rotational angular center of a steering wheel being rotated in a clockwise or counterclockwise direction, each revolution of said steering wheel having an original angular position corresponding to a rotational angle, wherein the original angular position for one of said revolutions is, the rotational angular center to be determined, said method comprising the steps of:

(a) arranging a position sensor including a photo interrupter and a rotary disk with a slit opening, said disk rotating in cooperation with the steering wheel, said position sensor having the capability of detecting each of said original angular positions for each of said revolutions;

(b) using said position sensor for detecting said original angular position for each of said revolutions;

(c) measuring a rotational angle of said steering wheel using the rotational angle of one of said detected original angular positions as a reference;

(d) determining that the measured rotational angle is the rotational angular center of said steering wheel when the measured rotational angle remains within a predetermined angular range for a predetermined period of time.

5. The method defined by claim 4 wherein said position sensor includes three photo-interrupters and a rotary disk with a plurality of slit openings disposed at an equiangular distance around said disk within a first concentric ring of said disk and a single silt opening disposed within a second concentric ring of said disk such that two of said photo-interruptors are disposed adjacent to each other at a passing position of said plurality of slit openings and said third photo-interrupter is disposed at a passing position of said single slit opening, wherein when said single slit opening passes by said third photo-interrupter, said steering wheel is at one of said original angular positions.

6. The method defined by claim 5 wherein as said plurality of slit openings pass by said first and second photo-interruptors, pulse signals are generated representing an amount of steering in a clockwise and counter-clockwise direction from said rotational angular center such that said amount is zero at said rotational angular center.

7. An apparatus for determining a rotational angular center of a steering wheel being rotated in a clockwise or counterclockwise direction, each revolution of said steering wheel having an original angular position wherein the original angular position for one of said revolutions is the rotational angular center to be determined, said apparatus comprising:

(a) a position sensor including a photo interrupter and a rotary disk with a slit opening, said disk rotating in cooperation with the steering wheel, said position sensor for detecting each of said original angular positions for each of said revolutions;

(b) means for assigning one of said detected original angular positions to be a potential rotational angular center of said steering wheel;

(c) means for determining that the assigned potential rotational angular position is the rotational angular center of said steering wheel when no other original angular position is detected within a predetermined period of time.

8. An apparatus for determining a rotational angular center of a rotary body as set forth in claim 7, wherein said rotational angle measuring means includes first and second UP/DOWN counters which input a signal representing a rotational angle of said rotary body to effect an up or down count with said rotational angular center being as a reference, said first UP/DOWN counter outputting its count value as angular information and replacing its count value with the content of said second UP/DOWN counter in response to the signal output from said timer means.

9. An apparatus for determining a rotational angular center of a rotary body as set forth in claim 8 further comprising comparing means in which a reference count value is set in advance, and comparing means comparing an output from said second UP/DOWN counter with said reference count value to reset said timer means in accordance with the compared result.

10. The apparatus defined by claim 7 wherein said position sensor includes three photo-interrupters and a rotary disk with a plurality of slit openings disposed at an equiangular distance around said disk within a first concentric ring of said disk and a single slit opening disposed within a second concentric ring of said disk such that two of said photo-interruptors are disposed adjacent to each other at a passing position of said plurality of slit openings and said third photo-interrupter is disposed at a passing position of said single slit opening, wherein when said single slit opening passes by said third photo-interrupter said steering wheel is at one of said original angular positions.

11. The apparatus defined by claim 10 wherein as said plurality of slit openings pass by said first and second photo-interruptors pulse signals are generated representing an amount of steering in a clockwise and counter-clockwise direction from said rotational angular center such that said amount is zero at said rotational angular center.

12. An apparatus for determining a rotational angular center of a steering wheel being rotated in a clockwise or counterclockwise direction, each revolution of said steering wheel having an original angular position corresponding to a rotational angle, wherein the original angular position for one of said revolutions is the rotational angular center to be determined, said apparatus comprising:

(a) a position sensor including a photo interrupter and a rotary disk with a slit opening, said disk rotating in cooperating with the steering wheel, said position sensor for detecting each of said original angular positions for each of said revolutions;

(b) means for measuring a rotational angle of said steering wheel using the rotational angle of one of said detected original angular positions as a reference;

(c) means for determining that the measured rotational angle is the rotational angular center of said steering wheel when the measured rotational angle remains within a predetermined angular range for a predetermined period of time.

13. An apparatus for determining a rotational angular center of a rotary body as set forth in claim 12, wherein said rotational angle measuring means includes first and second UP/DOWN counters which output a signal representing a rotational angle of said rotary body to effect an up or down count with said rotational angular center being a reference, said first UP/DOWN counter outputting its count value as angular information and replacing its count value with the contents of said second UP/DOWN counter in response to the signal output from said timer means.

14. An apparatus for determining a rotational angular center of a rotary body as set forth in claim 13 further comprising comparing means in which the predetermined range of angle is set in advance, said comparing means comparing an output from said second Up/DOWN counter with the predetermined range of angle to reset said timer means in accordance with the compared result.

15. The apparatus defined by claim 12 wherein said position sensor includes three photo-interrupters and a rotary disk with a plurality of slit openings disposed at an equiangular distance around said disk within a first concentric ring of said disk and a single slit opening disposed within a second concentric ring of said disk such that two of said photo-interruptors are disposed adjacent to each other at a passing position of said plurality of slit openings and said third photo-interrupter is disposed at a passing position of said single slit opening, wherein when said single slit opening passes by said third photo-interrupter, said steering wheel is at one of said original angular positions.

16. The apparatus defined by claim 15 wherein as said plurality of slit openings pass by said first and second photo-interruptors pulse signals are generated representing an amount of steering in a clockwise and counter-clockwise direction from said rotational angular center such that said amount is zero at said rotational angular center.