GRAVITY COMPENSATED ACCELERATION MEASURING APPARATUS

• US 3,712,109 A
• Filed: 10/05/1970
• Issued: 01/23/1973
• Est. Priority Date: 10/07/1969
• Status: Expired due to Term

• Current Assignee: Klaus Haken
• Original Assignee: Klaus Haken
• Inventors: Haken, Klaus
• Primary Examiner(s): Gill, James J.
• Application Number:
  US05/077,988
• Time in Patent Office: 841 Days
• Field of Search: 73/514-517,178R,178T 235/150.25,150.2,150.22
• US Class Current: 73/514.35
• CPC Class Codes: G01P 15/09 by piezoelectric pick-up
• CPC Class Codes: G01P 15/0907 of the compression mode type
• CPC Class Codes: G03B 15/00 Special procedures for taking photographs; Apparatus therefor

Abstract

The inertial reactive force on a proof mass being moved on an arbitrary inclined path due to the acceleration in the direction of the path is computed from two components of the bearing pressure of the suspended or supported proof mass, the one component being parallel and the other component being perpendicular to the direction of the path.

Claims

1. Apparatus for providing a measure of the linear acceleration of an object moving on an arbitrary inclined path, comprising proof mass means, first means connected to the proof mass means developing a first signal proportional to the force acting on the proof mass means in a direction parallel to the path, second means connected to the proof mass means for developing a second signal proportional to the force acting on the proof mass means in a direction perpendicular to the path, means for squaring said second signal to provide a third signal, means for generating a fourth signal proportional to the square of the weight of the proof mass, means to subtract the third signal from the fourth signal to provide a fifth signal, means to extract the square root of the fifth signal to provide a sixth signal, and means to sum the sixth and the fist signal.

2. Apparatus according to claim 1 wherein first and second means comprise piezoelectric crystals each of which is electrically connected to a charge amplifier.

3. Apparatus according to claim 1 wherein the first means comprises two piezoelectric crystals, one mounted on each side of the proof mass means along an axis parallel to the direction of the path, and the second means comprises a piezoelectric crystal supporting the proof mass means in a direction perpendicular to the direction of the path.

4. Apparatus according to claim 1 wherein the proof mass means is pendulously supported and rigidly connected with a shaft so as to allow pivoting about an axis, a piezoelectric crystal is mounted between the pivot axis and the proof mass means, the shaft is connected with the rotor of a resolver that produces an output signal equal to the sine of the angle the proof mass means pivot about said axis, said first means including a multiplier and developing said first signal by multiplying the output of said resolver and the output of said crystal.

5. Apparatus to claim 1 wherein the polarity of the sixth signal is made changeable by means of an inverter amplifier.

6. Apparatus according to claim 1 wherein the sum of the first and sixth signal is fed to the dividend input of a divider, the divisor input of which is connected to means for generAting a signal proportional to the weight of the proof mass.

7. Apparatus according to claim 1 wherein the means for squaring the second signal comprises a differential amplifier with a high no-load gain, the output signal of said amplifier is squared by a multiplier, whose output signal is fed back negatively to the input of said differential amplifier.

8. Apparatus according to claim 1 wherein first proof mass means and the first means are combined to a first accelerometer with its sensitive axis placed in a direction parallel to the path for developing the first signal, and second proof mass means and the second means are combined to a second, identically built accelerometer with its sensitive axis placed in a direction perpendicular to the path for developing the second signal.