Surface acoustic wave gyroscope
AssigneeThe Bendix Corporation
InventorBinneg Y. Lao
Life of this patent
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Abstract
A surface acoustic wave gyroscope which detects a change in the propagation velocity of a surface acoustic wave as a function of the rotational velocity of a medium on whose surface the acoustic wave is propogated, is disclosed. In a first embodiment using a fixed frequency oscillator to generate the surface acoustic wave, the change in the propagation velocity is detected as a phase shift between the generated and detected waves. In an alternate embodiment the detected surface acoustic wave is used as a feedback signal to an amplifier to form an oscillator whose frequency varies as a function of the surface waves propagation velocity. In the preferred embodiment, two surface acoustic waves are generated in opposite directions about the cylindrical surface of a substrate.
Claims39
A surface acoustic wave gyroscope comprising:
- a substrate having an axis of rotation and a surface displaced from and parallel to said axis of rotation;
- first means for generating at least one surface acoustic wave traversing said surface of said substrate with a wave particle motion in a plane normal to said axis;
- direction signal means for generating a first direction signal indicative of the direction of said rotation in response to the propagation velocity of said surface acoustic wave;
- and
- rate signal means for generating a rate signal indicative of the rotational velocity of said substrate relative to said axis in response to the propagation velocity of said surface acoustic wave.
A method for measuring the rotation of a substrate about an axis comprising the steps of:
- generating at a first location on the surface of the substrate at least one surface acoustic wave propagating along the surface of the substrate in a plane normal to the axis;
- detecting said surface acoustic wave at a second location on the surface of said substrate displaced from said first location along the propagation path of said surface acoustic wave to generate a detected signal;
- detecting the change in the phase of said detected signal due to the rotation of said substrate to generate a phase signal having a polarity component indicative of the direction of change in the surface acoustic wave's propagation velocity and a magnitude component indicative of the magnitude in the change in the surface acoustic wave's propagation velocity;
- processing the polarity component of said phase signal to generate a first direction signal indicative of the direction in which the substrate is rotating;
- and
- processing the magnitude component of said phase signal to generate a rate signal indicative of the rotational velocity of the substrate.
A surface acoustic wave gyroscope comprising:
- a substrate having an axis of rotation and a surface displaced from and parallel to said axis of rotation;
- first means for generating at least one surface acoustic wave traversing said surface of said substrate with wave particle motion in a plane normal to said axis;
- second means for generating signals indicative of the direction of rotation in response to the propagation velocity of said surface acoustic wave;
- and
- third means for generating signals indicative of the total angular displacement of said substrate from an initial position in response to the propagation velocity of said surface acoustic wave.
Dependencies are inferred from the claim text.