Road vibration compensated angular rate sensor

• US 6,305,222 B1
• Filed: 05/27/1999
• Issued: 10/23/2001
• Est. Priority Date: 05/27/1999
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Zarabadi, Seyed Ramezan, Johnson, Jack Daniel
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US09/321,449
• Time in Patent Office: 880 Days
• Field of Search: 73/13.7, 73/13.8, 735/040.2, 735/040.4, 735/040.8, 735/041.2, 735/041.8, 735/041.3
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5684 the devices involving a micromechanical structure

Abstract

A motion sensor (10) includes a micromachined sensing structure and a number of capacitive electrodes (20) disposed about a periphery thereof. The sensing structure includes a ring (14) supported above a substrate (12) so as to have an axis of rotation normal to the substrate (12), and a number of springs (16) attached to a post (18) positioned at the center of the ring (14). Certain diametrically opposed ones of the capacitive electrodes (20) are configured as drive electrodes (20a), and other diametrically opposed ones of the capacitive electrodes (20), positioned 90 degrees relative to the corresponding drive electrodes (20a) are configured as sense electrodes (20b). Signals produced at the opposed sense electrodes (20b) are conditioned and coupled to a common input of an amplifier circuit (64,70). With the configuration of the drive (20a) and sense (20b) electrodes and supporting circuitry (60-70), the resulting sensor (10) is operable to reject the effects of linear forces thereupon due to road vibrational effects.

Claims

1. A motion sensor comprising:

a sensing ring supported by a substrate;

a first pair of diametrically opposed drive electrode structures defined on said substrate about said ring and defining a first axis therethrough, said first pair of diametrically opposed drive electrode structures adapted to receive sensor drive signals thereat;

a first pair of diametrically opposed sense electrode structures defined on said substrate about said ring and defining a second axis therethrough normal to said first axis; and

a first amplifier having an input coupled to each of said first pair of diametrically opposed sense electrode structures and an output defining a first output of said motion sensor.

2. The motion sensor of claim 1 wherein said first pair of drive electrode structures and said first pair of sense electrode structures are integrated into said substrate.

3. The motion sensor of claim 1 wherein said first pair of drive electrode structures and said first pair of sense electrode structures are disposed on said substrate.

4. The motion sensor of claim 1 further including:

a second amplifier receiving a differential sense signal from one of said first pair of sense electrode structures and producing a first single ended sense signal at an output thereof; and

a third amplifier receiving a differential sense signal from the other of said first pair of sense electrode structures and producing a second single ended sense signal at an output thereof;

and wherein said outputs of said second and third amplifiers are connected to said input of said first amplifier.

5. The motion sensor of claim 4 wherein said first, second and third amplifiers are integrated into said substrate.

6. The motion sensor of claim 4 wherein said first, second and third amplifiers are disposed on said substrate.

7. The motion sensor of claim 4 wherein said first, second and third amplifiers are low input capacitance operational amplifiers.

8. The motion sensor of claim 1 further including:

a second pair of diametrically opposed drive electrode structures defined on said substrate about said ring and defining a third axis therethrough, said second pair of diametrically opposed drive electrode structures adapted to receive sensor drive signals thereat;

a second pair of diametrically opposed sense electrode structures defined on said substrate about said ring and defining a fourth axis therethrough normal to said third axis; and

a second amplifier having an input coupled to each of said second pair of diametrically opposed sense electrode structures and an output defining a second output of said motion sensor.

9. The motion sensor of claim 8 wherein said third axis is displaced from said first axis by approximately 45 degrees.

10. The motion sensor of claim 8 further including:

a third amplifier receiving a differential sense signal from one of said first pair of sense electrode structures and producing a first single ended sense signal at an output thereof;

a fourth amplifier receiving a differential sense signal from the other of said first pair of sense electrode structures and producing a second single ended sense signal at an output thereof;

a fifth amplifier receiving a differential sense signal from one of said second pair of sense electrode structures and producing a third single ended sense signal at an output thereof;

a sixth amplifier receiving a differential sense signal from the other of said second pair of sense electrode structures and producing a fourth single ended sense signal at an output thereof;

and wherein said outputs of said third and fourth amplifiers are connected to said input of said first amplifier, and said outputs of said fifth and sixth amplifiers are connected to said input of said second amplifier.

11. The motion sensor of claim 10 wherein said first, second, third, fourth, fifth and sixth amplifiers are integrated into said substrate.

12. The motion sensor of claim 10 wherein said first, second, third, fourth, fifth and sixth amplifiers are disposed on said substrate.

13. The motion sensor of claim 10 wherein said first, second, third, fourth, fifth and sixth amplifiers are low input capacitance operational amplifiers.

14. A motion sensor comprising:

a sensing ring supported by a substrate;

a first pair of diametrically opposed drive electrode structures defined on said substrate about said ring and defining a first axis therethrough, said first pair of diametrically opposed drive electrode structures adapted to receive sensor drive signals thereat;

a number of sense electrode structures defined on said substrate about said ring; and

a first amplifier having an input coupled to at least some of said number of sense electrode structures and an output defining a first output of said motion sensor.

15. The motion sensor of claim 14 further including:

a second pair of diametrically opposed drive electrode structures defined on said substrate about said ring and defining a second axis therethrough displaced from said first axis, said second pair of diametrically opposed drive electrode structures adapted to receive sensor drive signals thereat; and

a second amplifier having an input coupled to at least some remaining ones of said number of sense electrode structures and an output defining a second output of said motion sensor.

16. The motion sensor of claim 15 wherein said second axis is displaced from said first axis by approximately 45 degrees.

17. The motion sensor of claim 15 wherein said first and second pair of drive electrode structures and said number of sense electrode structures are integrated into said substrate.

18. The motion sensor of claim 15 wherein said first and second pair of drive electrode structures and said number of sense electrode structures are disposed on said substrate.

19. A method of minimizing road vibrational effects in a motion sensor having a sensing ring supported by a substrate and a number of electrode structures defined on said substrate about said ring, the method comprising the steps of:

configuring a first pair of diametrically opposed ones of said electrode structures as a first pair of drive electrodes adapted to receive sensor drive signals thereat;

configuring a second pair of diametrically opposed ones of said electrode structures as a first pair of sense electrodes, said first pair of sense electrodes defining a first axis therethrough normal to a second axis defined through said first pair of drive electrodes; and

summing sense signals produced by said first pair of sense electrodes at a first output of said motion sensor.

20. The method of claim 19 further including the steps of:

configuring a third pair of diametrically opposed ones of said electrode structures as a second pair of drive electrodes adapted to receive sensor drive signals thereat;

configuring a fourth pair of diametrically opposed ones of said electrode structures as a second pair of sense electrodes, said second pair of sense electrodes defining a third axis therethrough normal to a fourth axis defined through said second pair of drive electrodes and displaced from said first axis by approximately 45 degrees; and

summing sense signals produced by said second pair of sense electrodes at a second output of said motion sensor.