Electronically tunable resonant accelerometer

Silvus, Jr.

[45] Apr. 8,1980

[54] ELECTRONICALLY TUNABLE RESONANT ACCELEROMETER

[75] Inventor: Howard S. Silvus, Jr., San Antonio, Tex.

[73] Assignee: Southwest Research Institute, San Antonio, Tex.

[21] Appl. No.: 6,285

[22] Filed: Jan. 25, 1979

[51] Int. CM H01L 41/10

[52] U.S. CI 310/316; 310/317;

310/329; 310/325; 310/326; 73/517 R

[58] Field of Search 310/314, 316, 317, 329,

310/321, 325, 326, 328, 332, 331; 340/10;

73/517 R, 517 B

[56] References Cited

U.S. PATENT DOCUMENTS

2,594,841 4/1952 Arndt, Jr 310/316 X

3,336,529 8/1967 Tygart 310/321 X

3,447,051 5/1969 Attwood et al 310/325 X

3,714,475 1/1973 Baker, Jr 310/321

3,873,947 3/1975 Johnson 310/321 X

3,889,166 6/1975 Scurlock 310/325 X

Primary Examiner—Mark O. Budd
Attorney, Agent, or Firm—Gunn & Lee

[57] ABSTRACT

An electronically tunable resonant accelerometer is shown wherein the frequency of a resonant peak may be adjusted over a range of frequencies. A piezoelectric element of the accelerometer is used with a seismic mass to generate an output voltage in response to reciprocating motion of the accelerometer. In a compression mode, a feedback loop applies a feedback voltage to a second piezoelectric element mechanically coupled to the first mentioned piezoelectric element. In a cantilever mode, a feedback loop applies a feedback voltage to another location along the first mentioned piezoelectric element which is formed from two bonded piezoelectric elements. By adjusting gain and phase of the feedback loop, first, the resonant frequency of the accelerometer may be varied over a wide range of frequencies to give increased sensitivity to reciprocating motion occurring at a frequency within a narrow band width centered on the resonant frequency, and, second, damping of the resonance may be varied to control the band width of the resonance.

16 Claims, 7 Drawing Figures