System and technique for bandwidth improvement in multifunction sensors

• US 4,566,327 A
• Filed: 01/13/1984
• Issued: 01/28/1986
• Est. Priority Date: 04/21/1982
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Rider, Billie F.
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): Chapman, Jr., John E.
• Application Number:
  US06/570,479
• Time in Patent Office: 746 Days
• Field of Search: 73/504, 73/505, 73/510, 73/517 R, 307/515, 329/50
• US Class Current: 73/510
• CPC Class Codes: G01C 19/04 Details
• CPC Class Codes: G01C 19/28 Pick-offs, i.e. devices for taking-off an indication of the displacement of the rotor axis
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type

Abstract

A system and technique is disclosed for providing a low-cost, two-axis rate and acceleration transducer assembly which has improved bandwidth for providing outputs of acceleration while reducing ripple. The system includes a sensor structure utilizing piezoelectric generator elements affixed in a rotating configuration and generating a periodic signal having amplitudes representing the rates and accelerations. The structure includes three pairs of sensors, wherein each sensor of each pair of sensors is spaced 180° from the other sensor of that pair about a rotating hub structure. One pair provides two-axis rate signals, while the remaining two pair provide two-axis acceleration signals. In the remaining two pair, each of the sensors of a pair are spaced 180° from one another and 90° from one of the elements of the other pair. A demodulator is coupled to receive the combined output of each acceleration pair to produce low ripple signals without filtering or with reduced filtering.

Claims

1. A transducer and signal demodulating system comprising:

at least one first acceleration sensor and at least one second acceleration sensor mounted for rotation about a common axis, said at least one first and said at least one second sensor being angularly spaced by an angle of 90°

with respect to one another about said axis;

means for providing a first signal from said at least one first sensor and means for providing a second signal from said at least one second sensor;

means for receiving and varying the amplitude of each of said first and second signals for providing first and second transducer signals, respectively;

means coupled to said first transducer signal for providing an inverted first transducer signal and means coupled to said second transducer signal for providing an inverted second transducer signal;

first and second switch means for providing first and second demodulation outputs, each of said first and second switch means including a first switch having an input and output with the input of said first switch being coupled to receive said first transducer signal, a second switch having an input and an output with the input of said second switch being coupled to receive said inverted first transducer signal, a third switch having an input and an output with the input of said third switch being coupled to receive the second transducer signal, and a fourth switch having an input and an output with the input of said fourth switch being coupled to receive the inverted second transducer signal, the output of each of said first, second, third, and fourth switches of said first switch means being coupled in common to provide a first demodulation output and the output of each said first, second, third and fourth switches of said second switch means being coupled in common to provide a second demodulation output, each of said switches having a means for intermittently coupling the input of each switch to its output in response to a switching signal, wherein each of said demodulation outputs represents acceleration in an axis perpendicular to one another and to said common axis.

2. The system of claim 1 further comprising first and second operational amplifiers, each having an input coupled to receive a different one of the demodulation outputs and provide an output thereof.

3. The system of claim 1 wherein each of said first, second, third and fourth switches of the first switch means are driven by the same switching signal as the first, second, third, and fourth switches, respectively, of the second switch means.

4. A transducer and signal demodulating system comprising:

at least one first acceleration sensor and at least one second acceleration sensor mounted for rotation about a common axis, said at least one first and said at least one second sensor being angularly spaced by an angle of 90°

with respect to one another about said axis;

means for providing a first signal from said at least one first sensor and means for providing a second signal from said at least one second sensor;

means for receiving and varying the amplitude of each of said first and second signals for providing first and second transducer signals, respectively;

means coupled to said first transducer signal for providing an inverted first transducer signal and means coupled to said second transducer signal for providing an inverted second transducer signal;

first and second switch means for providing first and second demodulation outputs, each of said first and second switch means including a first switch having an input and output with the input of said first switch being coupled to receive said first transducer signal, a second switch having an input and an output with the input of said second switch being coupled to receive said inverted first transducer signal, a third switch having an input and an output with the input of said third switch being coupled to receive the second transducer signal, and a fourth switch having an input and an output with the input of said fourth switch being coupled to receive the inverted second transducer signal, the output of each of said first, second, third, and fourth switches of said first switch means being coupled in common to provide a first demodulation output and the output of each said first, second, third and fourth switches of said second switch means being coupled in common to provide a second demodulation output, each of said switches having a means for intermittently coupling the input of each switch to its output in response to a squarewave switching signal, wherein each of said first, second, third and fourth switches of the first switch means are driven by the same squarewave switching signal as the first, second, third, and fourth switches, respectively, of the second switch means, and each of said demodulation outputs represents acceleration in an axis perpendicular to one another and to said common axis.

5. A transducer and signal demodulation system comprising:

first and second acceleration sensors mounted about a common axis and angularly spaced about that axis by 180°

with respect to one another;

third and fourth acceleration sensors mounted for rotation about said common axis and angularly spaced from one another by 180°

, said third and fourth sensors each being angularly spaced from said first and second sensors about said common axis by 90°

;

means coupled to each sensor for providing a sensor signal;

means for coupling the sensor signals of said first and second sensors in common to provide a first transducer signal;

means for coupling the sensor signals of said third and fourth sensors in common to provide a second transducer signal;

means coupled to said first transducer signal for providing an inverted first transducer signal and means coupled to said second transducer signal for providing an inverted second transducer signal;

first and second switch means for providing first and second demodulation outputs, each of said first and second switch means including a first switch having an input and output with the input of said first switch being coupled to receive said first transducer signal, a second switch having an input and an output with the input of said second switch being coupled to receive said inverted first transducer signal, a third switch having an input and an output with the input of said third switch being coupled to receive the second transducer signal, and a fourth switch having an input and an output with the input of said fourth switch being coupled to receive the inverted second transducer signal, the output of each of said first, second, third, and fourth switches of said first switch means being coupled in common to provide a first demodulation output and the output of each said first, second, third and fourth switches of said second switch means being coupled in common to provide a second demodulation output, each of said switches having a means for intermittently coupling the input of each switch to its output in response to a switching signal, and wherein said first and seoond demodulation outputs represent acceleration in two axes which are perpendicular to one another and to said common axis.

6. The system of claim 5 wherein said acceleration sensors are piezoceramic elements.

7. A transducer and demodulation system comprising:

first and second acceleration sensors mounted about a common axis and angularly spaced about that axis by 180°

with respect to one another;

third and fourth sensors mounted for rotation about said common axis and angularly spaced from one another by 180°

, said third and fourth sensors each being spaced angularly from said first and second sensors about said common axis by 90°

;

means associated with each sensor for providing a sensor signal;

means for coupling the sensor signals of said first and second sensors in common to provide a first transducer signal;

means for coupling the sensor signals of said third and fourth sensors in common to provide a second transducer signal;

a first rate sensor and a second rate sensor coupled for rotation about said common axis and angularly spaced 180°

with respect to one another about said common axis and 450°

with respect to at least one of said acceleration sensors;

means for providing a rate sensor signal from each of said rate sensors;

means for demodulating the rate sensor signals for providing two axis rate signals;

means coupled to said first transducer signal for providing an inverted first transducer signal and means coupled to said second transducer signal for providing an inverted second transducer signal;

first and second switch means for providing first and second demodulation outputs, each of said first and second switch means including a first switch having an input and output with the input of said first switch being coupled to receive said first transducer signal, a second switch having an input and an output with the input of said second switch being coupled to receive said inverted first transducer signal, a third switch having an input and an output with the input of said third switch being coupled to receive the second transducer signal, and a fourth switch having an input and an output with the input of said fourth switch being coupled to receive the inverted second transducer signal, the output of each of said first, second, third, and fourth switches of said first switch means being coupled in common to provide a first demodulation output and the output of each said first, second, third and fourth switches of said second switch means being coupled in common to provide a second demodulation output, each of said switches having a means for intermittently coupling the input of each switch to its output in response to a switching signal; and

means for providing a switching signal to each of said first, second, third and fourth switches of said first and second switch means such that the same switching signal is applied to the corresponding switches of each switch means.