Transducer element for measuring angular and linear acceleration

• US 4,996,878 A
• Filed: 02/09/1990
• Issued: 03/05/1991
• Est. Priority Date: 01/29/1988
• Status: Expired due to Term

• Current Assignee: Kistler Instrumente AG (Kistler Holding AG)
• Original Assignee: Kistler Instrumente AG (Kistler Holding AG)
• Inventors: Kubler, John
• Primary Examiner(s): Chapman, John
• Application Number:
  US07/478,017
• Time in Patent Office: 389 Days
• Field of Search: 73/510, 73/517 R, 73/517 A, 73/651, 310/329
• US Class Current: 73/510
• CPC Class Codes: G01N 2291/02827 Elastic parameters, strength or force
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges

Abstract

A transducer element for measuring angular and linear accelerations including a pair of electromechanically reacting oscillating beams held symmetrical to a main axis y on a base plate by fixing elements. The electrical output signals proportional to the flexure of the beams under rotation about the y axis are provided to a signal processing circuit, which is designed so that with similar or dissimilar polarity of the oscillating beams a summing amplifier determines the linear acceleration along the z axis and a differential amplifier the angular acceleration about the y axis. The oscillating beams may be piezoelectric bending elements, or bending elements coated with piezoresistive semiconductors, or else provided with strain gauges.

Claims

1. Transducer element for measuring angular and linear acceleration comprising:

a pair of electromechanical beams extending along a first axis in a common plane and cantileverly mounted to at least one fixing element substantially at a second axis perpendicular to said plane of said beams and symmetrical with respect to a third axis orthogonal to said first and second axis;

means for fixedly mounting said fixing element to an object whose angular acceleration about said third axis and linear acceleration along said second axis are to be measured;

each of said beams comprising piezoelectric material having a specific electrical polarization direction;

first means for connecting electrical output signals generated by the flexure of the beams to a signal processing facility as a sum of the output signals if the material of the beams have different electrical polarization directions and as a difference of the output signals if the electrical polarization directions are the same, to produce a measuring signal representing the angular acceleration of the object about the third axis; and

second means for connecting said output signals to a signal processing facility as a sum of the output signals from the beams if the material of the beams have the same electrical polarization directions and as a difference of the output signal if the electrical polarization directions are dissimilar, to produce a measuring signal for the linear acceleration along said second axis at right angles to the plane of the beams.

2. Transducer element according to claim 1, wherein said first means includes conductors connecting terminals of said beams in addition if said material of said beams have different electrical polarization directions and in subtraction if said material of said beams have the same electrical polarization directions;

and

said second means includes conductors connecting said terminal of said beams in subtraction if said material of said beams have different electrical polarization directions and in addition if said material of said beams means have the same electrical polarization directions.

3. Transducer element according to claim 1, wherein said first means includes a difference amplifier connected to different polarity terminals of said beams if said material of said beams have different electrical polarization directions and to same polarity terminals of said beams if said material of said beams have the same electrical polarization directions;

and

wherein said second means includes a summing amplifier connected to different polarity terminals if said material of said beams have different electrical polarization directions and to same polarity terminals if said material of said beams have the same electrical polarization directions.

4. Transducer element according to claim 1, wherein said fixing element is fixedly mounted to a base plate joinable to a housing.

5. An accelerometer for measuring angular and linear acceleration comprising:

a housing having first, second and third orthogonal axes;

at least one transducer element having a pair of electromechanical beams extending along said first axis in a common plane and cantileverly mounted to at least one fixing element substantially at said second axis perpendicular to said plane of said beams and symmetrical with respect to said third axis orthogonal to said first and second axis, each of said beams comprising piezoelectric material having a specific electrical polarization direction;

means for fixedly mounting said fixing element to said housing along said second axis;

means for fixedly mounting said housing to an object whose angular acceleration about said third axis and linear acceleration about said second axis are to be measured; and

signal processing means in said housing for receiving electrical output signal generated by the flexure of the beams, for adding said output signals if the material of the beams have different electrical polarization directions and subtracting the output signals if the electrical polarization directions are the same to produce an angular acceleration measuring signal about said third axis, and for adding said output signals if the material of said beams have the same electrical polarization directions and subtracting said output signals if the electrical polarization directions are different to produce a linear acceleration measuring signal along said second axis.