Single plate capacitive acceleration derivative detector

• US 7,124,634 B2
• Filed: 07/29/2003
• Issued: 10/24/2006
• Est. Priority Date: 07/29/2003
• Status: Expired due to Fees

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Campbell, Ray F., Wada, Joan D.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): BELLAMY, TAMIKO D
• Application Number:
  US10/604,537
• Publication Number:
  US 20050022598A1
• Time in Patent Office: 1,183 Days
• Field of Search: 735/143.2, 735/143.6, 735/041.5, 735/03, 324/661, 361/280, 438/379
• US Class Current: 73/514.32
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

A capacitance accelerometer includes a housing, and a plate fixed within the housing. A moveable plate is disposed in substantially parallel relation to the fixed plate and is coupled to the housing along at least an edge. The moveable plate and the fixed plate define a distance. The distance varies in response to acceleration forces acting upon the moveable plate, and wherein the moveable plate and the fixed plate generate a charge displacement capacitance signal. A transimpedance amplifier receives the charge displacement capacitance signal and generates a scaled voltage signal therefrom. An acceleration signal is generated from the scaled voltage signal.

Claims

1. A single plate capacitive acceleration derivative detector comprising:

a housing;

a plate fixed within said housing;

a moveable plate disposed in substantially parallel relation to said fixed plate, said moveable plate coupled to said housing along at least an edge, said moveable plate and said fixed plate defining a distance,

wherein said distance varies in response to acceleration forces acting upon said moveable plate, and wherein said moveable plate and said fixed plate generate a charge displacement capacitance signal as a function of a signal from a power source in series with said moveable plate and said fixed plate and as a function of said distance;

a transimpedance amplifier receiving said charge displacement capacitance signal and generating a scaled voltage signal therefrom, wherein an acceleration signal is generated from said scaled voltage signal;

an analog-to-digital converter receiving said scaled voltage signal and generating a digital voltage signal therefrom; and

a time integrator integrating said digital voltage signal in response to initialization parameters and generating an integrated signal therefrom, whereby voltage polarity of said digital voltage signal provides direct indication of a direction of acceleration.

2. The system of claim 1 further comprising a linearizer receiving said integrated signal and generating therefrom a linearized acceleration signal.

3. The system of claim 2 wherein said linearizer comprises a linear lookup table.

4. The system of claim 2 further comprising an actuator activating a system component in response to a system control signal;

and a processor receiving said linearized acceleration signal and generating said system control signal in response thereto.

5. The system of claim 1 wherein said moveable plate comprises a flexured diaphragm, a cantilevered beam, a flexible beam, or any object which moves under acceleration with respect to said fixed plate.

6. A method for operating a single plate capacitive acceleration derivative detector system having a single moveable plate and a single fixed plate comprising;

accelerating the single moveable plate, thereby causing a distance between the single moveable plate and the single fixed plate to change;

generating a variable capacitor signal;

generating a scaled voltage signal in response to said variable capacitor signal; and

generating an acceleration signal in response to said scaled voltage signal,

wherein generating said acceleration signal further comprises generating a digital voltage signal,

wherein generating said acceleration signal further comprises generating an integrated voltage signal in response to initialization parameters and integrating said digital voltage signal, whereby voltage polarity of said digital voltage signal provides direct indication of a direction of acceleration.

7. The method of claim 6, wherein generating said acceleration signal further comprises linearizing said integrated voltage signal and generating a linearized signal therefrom.

8. The method of claim 7, wherein generating said acceleration signal further comprises filtering said linearized signal and generating said acceleration signal therefrom.

9. The method of claim 8 further comprising activating an object control device in response to said acceleration signal.

10. A system for controlling acceleration including an object adapted to accelerate comprising:

a platform;

a first accelerometer coupled to said platform and comprising a first variable capacitor sensor comprising a housing, a flexured diaphragm, comprising a side and an edge, said edge coupled to said housing structure,

a fixed plate coupled to said housing at a distance from said side of said flexured diaphragm,

said flexured diaphragm being flexible under acceleration forces wherein said distance varies as a function of said acceleration forces to generate a charge displacement capacitance signal in response to change in said distance;

a transimpedance amplifier receiving said charge displacement capacitance signal and generating a time-varying voltage signal in response thereto;

an analog-to-digital converter receiving said time-varying voltage signal and generating a digital voltage signal therefrom;

a time integrator integrating said digital voltage signal in response to initialization parameters and generating an integrated signal therefrom whereby voltage polarity of said digital voltage signal provides direct indication of acceleration;

a linearizer receiving said integrated signal and generating therefrom a linearized acceleration signal; and

a processor coupled to said first accelerometer receiving said linearized acceleration signal and generating a system control signal in response thereto.

11. The system of claim 10 further comprising an object control device activating in response to said system control signal, said object control device comprising at least one of a thruster, an attitude control device, a missile steering nozzle, or a vane actuator.

12. The system of claim 10 further comprising a second accelerometer coupled to said platform orthogonal to said first accelerometer, said second accelerometer generating a second accelerometer signal in response to movement of the system, wherein said processor further generates said system control signal in response to said second accelerometer signal.

13. The system of claim 12 further comprising a third accelerometer, wherein said second and third accelerometers are arranged with said first accelerometer to receive cross axis thrust data, wherein said processor generates said system control signal in response to said cross axis thrust data.

14. The system of claim 13 further comprising a serial data bus receiving acceleration signals from said first, second and third accelerometers, said serial data bus exchanging information with said processor.