PAUL L WARD
Gas Fitter in Boston, MA

6674294, Jan 6, 2004

Aug 30, 2002

10/232278

Paul Ward - Roslindale MA

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

G01P 904

324684, 324687, 324690, 324658, 324659, 324667, 324668, 324669

The present invention relates to a system for nulling drive feedthrough error in a sensor having first and second drive electrodes which impart vibratory motion to first and second proof masses in response to first and second opposite phase drive signals, and having first and second capacitances defined between the drive electrodes and their associated proof masses. A mismatch between the first and the second capacitance is measured. Drive feedthrough caused by the measured capacitance mismatch is nulled by adjusting the relative amplitudes of the first and second opposite phase drive signals, whereby the ratio of the amplitudes is proportional to the ratio of the first and second capacitances. A servo loop may adaptively effect the ratio of amplitudes.

5783973, Jul 21, 1998

Feb 24, 1997

8/804796

Marc S. Weinberg - Needham MA
Paul A. Ward - Roslindale MA
Anthony S. Kourepenis - Acton MA

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

H03L 700

331 35

Micromachined, thermally insensitive silicon resonators are provided having accuracy equivalent or superior to that of quartz resonators, and are fabricated from a micromechanical, silicon-on-glass process. In one embodiment, such a resonator is realized using a tuning fork gyroscope. Radiation-hard precision voltage references (PVRs) are enabled using the silicon resonators. Thermal sensitivity is reduced relative to that of a silicon-on-silicon process oscillator, providing a thermal sensitivity comparable to that of a quartz oscillator. By employing a micromechanical device based upon a tuning fork gyroscope, resonators are made from either or both of the gyro drive and sense axes. A resonator constructed as an oscillator loop whose resonant frequency is compared to a frequency standard provides a bias voltage as a reference voltage.

5808198, Sep 15, 1998

May 19, 1997

8/858522

Paul A. Ward - Roslindale MA
William P. Kelley - Beverly MA

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

G01P 1500

7351432

An RF balanced capacitive vibration sensor system includes a carrier generator for generating an r. f. carrier and an inverted r. f. carrier; a voltage tunable capacitive vibration sensor responsive to one of the carriers; a reference capacitor responsive to the other of the carriers; a summing device for combining the outputs from the sensor and reference capacitors; a controller device for adjusting the amplitude of the carriers to tune the capacitance of the sensor to that of the reference capacitor; the sensor modulating one of the carriers with a vibration modulation signal representative of a sensed vibration; an r. f. amplifier device responsive to the summing device for amplifying the modulated carrier from the sensor; and a detector device, responsive to the modulated carrier from the r. f. amplifier, for detecting the modulation signal representative of the sensed vibration.

5911156, Jun 8, 1999

Feb 24, 1997

8/805013

Paul A. Ward - Roslindale MA
Eric M. Hildebrant - Watertown MA
Lance C. Niles - Salem MA
Marc S. Weinberg - Needham MA
Anthony S. Kourepenis - Acton MA

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

G01C 1900

7350416

A micromechanical tuning fork gyroscope having two center electrodes is disclosed. The two center electrodes are excited with bias potentials of opposite polarity. The oppositely biased center electrodes provide electrical symmetry across the gyroscope and thereby reduce charge transients and sensitivity to vertical translation. Currents injected directly into the proof masses are equal and opposite and thus cancel. Motor lift forces acting on the proof masses and interleaved electrodes are equal, and hence the proof masses move in pure translation, thereby reducing in-phase bias. Further, any pure translation normal to the plane of the gyroscope does effect sense axis output signals.

5952574, Sep 14, 1999

Apr 29, 1997

8/841224

Marc S. Weinberg - Needham MA
Steven T. Cho - Santa Clara CA
Ralph E. Hopkins - Brookline MA
Lance C. Niles - Salem MA
Anthony S. Kourepenis - Acton MA
Eric M. Hildebrant - Watertown MA
Paul A. Ward - Roslindale MA

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

G01C 1900

7350416

Trenches which reduce or eliminate force and sensitivity associated with proof mass motion normal to the substrate as a result of voltage transients is disclosed. The trenches provide increased separation between interleaved comb electrodes and the substrate, and thereby also reduce the comb lift to drive ratio. The trenches are typically formed directly below the interleaved comb electrodes, but may also be formed below other suspended portions. Trench depth is from 6-10 microns and provides a comb electrode to substrate separation of approximately 8. 5-12. 5 microns.

6064169, May 16, 2000

Oct 11, 1995

8/540809

Paul A. Ward - Roslindale MA
Anthony S. Kourepenis - Acton MA
Marc S. Weinberg - Needham MA

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

H03B 530, G05D 1500

318646

A control system for a tuning fork gyroscope uses motor frequency to control motor amplitude. The tuning fork gyroscope has a drive signal input and an output signal from which motor frequency is determined. A phase/frequency detector generates an error signal by comparing the actual oscillation phase of the output signal with the phase of a reference signal from a crystal controlled frequency synthesizer. The error signal is filtered in a feedback loop control to reduce phase detector ripple. The output of the loop controller is then used to determine the appropriate drive signal to drive the error signal to a constant and maintain a predetermined oscillation frequency.

2004003, Feb 26, 2004

Mar 26, 2003

10/397577

Paul Ward - Roslindale MA, US
Jeffrey Borenstein - Holliston MA, US
Christopher Lento - Somerville MA, US

G01P015/125, G01P015/14

073/514320, 073/504160

A capacitive sensor such as a tuning-fork gyroscope or accelerometer having a reduced bias error. The electrical connection of the first capacitive plate to, e.g., a signal measuring device or a voltage source, induces a first voltage difference at the junction. The materials of the second capacitive plate are selected such that its electrical connection to, e.g., a signal measuring device or a voltage source, induces a second voltage difference that substantially offsets the first voltage difference and reduces the bias error. One embodiment forms the capacitive plates, e.g., a proof mass and a sense plate, from substantially identical doped semiconductors.

5747961, May 5, 1998

Oct 11, 1995

8/541079

Paul A. Ward - Roslindale MA
Anthony S. Kourepenis - Acton MA

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

G01P 1514

318646

A tuning fork gyroscope has an in-plane position sensitive pick-off to which an AC or AC+DC bias is applied. Intermodulation is exploited to produce beat-notes between the applied frequency and the motor frequency at amplitudes proportional to motor amplitude, but unaffected by error sources such as spurious substrate charge accumulation. The beat-notes are used to control motor amplitude without the effects of charge accumulation.

6873206, Mar 29, 2005

Apr 19, 2001

09/839184

Eric M. Hildebrant - Watertown MA, US
Paul A. Ward - Roslindale MA, US
Robert A. Bousquet - Somerville MA, US
Shida Iep Martinez - Andover MA, US
Harold Ralph Haley - Reading MA, US

Charles Stark Draper Laboratory, Inc. - Cambridge MA

G06G007/26

327560, 327561, 327563, 330253, 330259, 330260

A fully integrated charge amplifier with DC stabilization includes a first amplifier having an input terminal and an output terminal, a first capacitor coupled between the input terminal and the output terminal of the first amplifier, a transimpedance amplifier having an input terminal coupled to the output terminal of the first amplifier and an output terminal, and an impedance device coupled between the input terminal of the first amplifier and the output terminal of the second amplifier. The impedance device has a resistance of at least 1 MΩ.