Angular rate sensor system
DCFirst Claim
1. An angular rate sensor system comprising:
- (a) a tuning fork formed from a single crystal of piezoelectric material, said tuning fork having two tines and a common shaft disposed in a plane, said common shaft serving as an output shaft, said tuning fork providing a balanced resonant sensor responsive solely to a component of angular motion about the longitudinal axis of the output shaft, causing a torsional deflection of said output shaft(b) driving means coupled to said tines for causing them to vibrate at a drive frequency(c) electrode means, responsive to piezeoelectric signals, positioned on said tuning fork for sensing said piezoelectric signals representative of the angular rate of motion about said axis to which said system is subjected and(d) output means including a phase detector for said piezeoelectric signals and means for generating an output signal indicative of the angular rate of motion.
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Abstract
An angular rate sensor system is disclosed, consisting of a balanced resonant sensor. The sensor consists of a tuning fork of a piezoelectric material, preferably of quartz. The tines of the tuning fork are caused to vibrate electromechanically, for example, by impressing an alternating voltage on a pair of electrodes on each tine. This will cause the tines to vibrate. Any component of angular motion around the axis of the sensor causes a cyclic deflection of the tines at right angles to the normal driven vibration of the tines. If the rotational input to the handle of the sensor is applied through a torsion element, the resulting tine deflection is directed to cyclically rotate the entire sensor along the input/output axis. This deflection can be used for changing the capacitance of a capacitance bridge, or for generating an electric signal, due to the piezoelectric effect resulting from the deflection. Finally, the output signal may consist of a frequency-modulated signal or an optical pick-up may be used. The system may take various forms, including one, two, four, or eight tuning forks forming a unitary system.
180 Citations
42 Claims
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1. An angular rate sensor system comprising:
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(a) a tuning fork formed from a single crystal of piezoelectric material, said tuning fork having two tines and a common shaft disposed in a plane, said common shaft serving as an output shaft, said tuning fork providing a balanced resonant sensor responsive solely to a component of angular motion about the longitudinal axis of the output shaft, causing a torsional deflection of said output shaft (b) driving means coupled to said tines for causing them to vibrate at a drive frequency (c) electrode means, responsive to piezeoelectric signals, positioned on said tuning fork for sensing said piezoelectric signals representative of the angular rate of motion about said axis to which said system is subjected and (d) output means including a phase detector for said piezeoelectric signals and means for generating an output signal indicative of the angular rate of motion. - View Dependent Claims (2, 3, 4, 9, 10, 13, 14, 15, 16, 17)
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5. An angular rate sensor comprising:
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(a) a single crystal of quartz having two substantially parallel sections, each of said sections being provided at its center with a first gap, leaving a small bridge between the two portions of each section, each portion forming a tine of a tuning fork; (b) said sections being interconnected at each end by an interconnecting member forming an output shaft, each of said members being separated from its associated section by a second gap leaving a small bridge between each member and its associated section, said gaps controlling said tine inertia and frequency of said sensor, whereby the dimensions of said gaps and of said portions and the masses of said sections, portions and members determine the resonant frequency of said tines and the frequency of an output signal indicative of the angular rate of motion to which said sensor is subjected. - View Dependent Claims (6, 7, 8)
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11. An angular rate sensor system comprising:
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(a) a single crystal resonant structure exhibiting piezoelectric properties, said structure having at least two vibrating elements, each of said vibrating elements comprising two tines and a common shaft, said tines and shaft being disposed in a plane, said common shaft serving as an output shaft, said single crystal structure providing a balanced resonant sensor responsive solely to a component of angular motion about the longitudinal axis of said output shaft, causing a torsional deflection on said output shaft (b) driving means coupled to said tines for causing them to vibrate at a drive frequency and (c) output means coupled to said output shaft for detecting a piezoelectric signal representative of the angular rate of motion about said axis to which said system is subjected. - View Dependent Claims (12, 18, 19, 20, 21, 22)
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23. An angular rate sensor comprising:
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a single crystal of piezoelectric material having at least two tines symmetrically disposed in a plane about a common shaft, which are vibrated in first and second opposing directions in said plane, and electrodes mechanically connected to said single crystal for piezoelectrically measuring stresses caused by the movement of said tines in third and fourth opposing directions orthogonal to said plane caused by rotation of said vibrated tines. - View Dependent Claims (24, 25, 26)
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27. An angular rate sensor comprising:
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a single crystal of piezoelectric material formed as first and second tines disposed symmetrically about a common axis first and second sets of electrodes attached to said first and second tines of said single crystal of piezoelectric material for subjecting said tines to oscillating voltages, thereby causing said tines to vibrate in a plane and a third set of electrodes attached to said single crystal of piezoelectric material to detect piezoelectric voltages generated by said material caused by movement of said tines in directions orthogonal to said plane when said material is rotated.
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28. A gyroscope comprising:
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a single crystal of piezoelectric material having first and second tines a driver for piezoelectrically driving said tines to move said tines along first paths and a sensor for sensing rotation of said piezoelectric material by piezoelectrically detecting stress caused by the tendency of said tines to continue moving along said first paths. - View Dependent Claims (29, 30, 31, 32, 33)
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34. A gyroscope comprising:
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a single crystal of piezoelectric material having a first portion comprising first and second tines which are driven along first and second paths, said first and second paths disposed in a common plane and a sensor mechanically connected to a second portion of said single crystal to piezoelectrically measure stresses caused in said second portion of said single crystal by rotation of said tines of said single crystal which forces said tines to move along a path other than said first path. - View Dependent Claims (35, 36)
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37. A method of sensing rotation comprising the steps of:
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vibrating the tines of a single, tuning fork-shaped crystal having piezoelectric properties in a first plane and sensing piezoelectric voltages generated by stresses within said vibrating single crystal resulting from the movement of said tines in directions orthogonal to said plane caused by the rotation of said single crystal. - View Dependent Claims (38)
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39. A method of sensing rotation of a gyroscope which includes a single crystal of piezoelectric material having at least first and second tines comprising a tuning fork with said two tines and a common shaft disposed in a plane, the method comprising the steps of:
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electrically driving tines of said single crystal of piezoelectric material to move the tines of said single crystal along a first path; and piezoelectrically detecting stress in said single crystal caused by the tendency of said tines to continue moving along said first path, thereby detecting rotation of said single crystal of piezoelectric material. - View Dependent Claims (40, 41, 42)
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Specification