Christopher E Townsend

US Patent:

6433629, Aug 13, 2002

Filed:

Jan 24, 2001

Appl. No.:

09/768858

Inventors:

Michael John Hamel - Williston VT
Christopher P. Townsend - Shelburne VT
Steven W. Arms - Williston VT

Assignee:

Microstrain, Inc. - Burlington VT

International Classification:

H02M 7162

US Classification:

327588, 327587, 327448

Abstract:

A sensing device includes a Wheatstone bridge and a source of a stimulation configured to apply the stimulation across two electrodes of the Wheatstone bridge. The device also includes a timing sensitive circuit configured to detect timing of a signal appearing across one of the other electrodes of the bridge as a result of the stimulation being applied. The timing provides a way to read the sensor. The device can be powered remotely and data so read can be transmitted using the remote power. The timing sensitive circuit includes a comparator. The comparator provides a high logic signal for a time related to the reactance of one leg of the Wheatstone bridge, and that provides a reading of a differential sensor having elements in each leg of the bridge.

US Patent:

6499368, Dec 31, 2002

Filed:

Apr 28, 1998

Appl. No.:

09/067710

Inventors:

Steven Willard Arms - Burlington VT
Christopher Pruyn Townsend - Shelburne VT
Steven Ward Mundell - Williston VT

Assignee:

Microstrain, Inc. - Williston VT

International Classification:

G01D 2100

US Classification:

7386615, 32420719, 33556

Abstract:

The novel sensor assembly is comprised of a threaded housing with pressure relief tracks through the threads that terminate at a hole through the housing and a displacement sensor. In the preferred embodiment, we have included an integral connector, a super-elastic core carrier and a Differential Variable Reluctance Transducer. Other sensor types could be used to construct a pressure equalized displacement sensor as described herein, these may include: capacitive, resistive, Hall effect, eddy current, and differential variable transformer. The sensor is attached to a keyed connector and the entire assembly is potted into the housing. A temperature probe can also be potted with this assembly to allow for multiple tasks t o be performed by this one housing. The housing is threaded on one end to allow for easy mounting. A hole is drilled through the housing just in back of the sensor and two tracks run perpendicular to and slightly deeper than the threads.

US Patent:

6529127, Mar 4, 2003

Filed:

Jul 11, 1998

Appl. No.:

09/114106

Inventors:

Christopher Pruyn Townsend - Shelburne VT
Steven Willard Arms - Williston VT

Assignee:

Microstrain, Inc. - Williston VT

International Classification:

G08B 2300

US Classification:

340505, 3405724, 3405731, 340 561, 340 101, 340 105

Abstract:

A multidrop network of multichannel, addressable sensing modules (ASMs), to be embedded within a composite structure, remotely powered, and interrogated by a personal computer through a non-contacting inductive link. Each ASM contains a microprocessor with non-volatile memory, multiplexer, programmable gain and filter instrumentation amplifier, and sigma delta analog to digital converter (all housed in two thin surface mount packages). An embedded mothernode includes circuitry for power and data reception (into the structure), and data transmission (back out of the structure). The external interrogation system communicates into the network of ASMs by modulating the AC waveform that delivers power to the embedded electronics. Once addressed, each ASM powers up its programmable (gain filter) sensing channels (3 full differential or 5 pseudo differential) and data conversion elements. Sensed data are pulse code modulated, including error checking, which serially modulate an RF carrier for wireless transmission out of the composite to the interrogating computer.

US Patent:

6622567, Sep 23, 2003

Filed:

Mar 7, 2001

Appl. No.:

09/801230

Inventors:

Michael John Hamel - Williston VT
Christopher Prvyn Townsend - Shelburne VT
Steven W. Arms - Williston VT

Assignee:

Microstrain, Inc. - Williston VT

International Classification:

G01M 500

US Classification:

73786, 73789

Abstract:

A sensing device includes an RFID chip and a differential variable reluctance transducer (DVRT) sensor that can be read remotely with electromagnetic power provided to the device from a remote reader. The ac signal provided to the device by inductance is used for powering the RFID chip and exciting the sensor. Data read from the sensor can also be transmitted back to the reader using the power provided by the reader. The sensor circuit uses a lower amount of current than the RFID chip, so it does not contribute appreciably to device power requirements.

US Patent:

6714763, Mar 30, 2004

Filed:

Aug 9, 2002

Appl. No.:

10/215752

Inventors:

Michael John Hamel - Williston VT
Christopher P. Townsend - Shelburne VT
Steven W. Arms - Williston VT

Assignee:

Microstrain, Inc - Williston VT

International Classification:

H04B 500

US Classification:

455 41, 4551271, 455572, 340827

Abstract:

A sensing device includes a Wheatstone bridge and a source of a stimulation configured to apply the stimulation across two electrodes of the Wheatstone bridge. The device also includes a timing sensitive circuit configured to detect timing of a signal appearing across one of the other electrodes of the bridge as a result of the stimulation being applied. The timing provides a way to read the sensor. The device can be powered remotely and data so read can be transmitted using the remote power. The timing sensitive circuit includes a comparator. The comparator provides a high logic signal for a time related to the reactance of one leg of the Wheatstone bridge, and that provides a reading of a differential sensor having elements in each leg of the bridge.

US Patent:

6828779, Dec 7, 2004

Filed:

Jul 24, 2001

Appl. No.:

09/911959

Inventors:

Christopher Townsend - Shelburne VT
Steven Arms - Williston VT

Assignee:

Microstrain, Inc. - Williston VT

International Classification:

G01B 714

US Classification:

32420712, 32420724, 324225

Abstract:

A sensing device includes a circuit that compensates for time and spatial changes in temperature. The circuit includes elements to correct for variation in permeability of a highly permeable core of a differential variable reluctance transducer as temperature changes. The circuit also provides correction for temperature gradients across coils of the transducer.

US Patent:

6834436, Dec 28, 2004

Filed:

Feb 23, 2002

Appl. No.:

10/082562

Inventors:

Christopher P. Townsend - Shelburne VT
Steven W. Arms - Williston VT

Assignee:

MicroStrain, Inc. - Williston VT

International Classification:

G01B 100

US Classification:

33512, 33341, 600301, 482 8

Abstract:

A sensing device is attached to a living subject that includes a first sensors for distinguishing lying, sitting, and standing positions. In another embodiment, sensor data is stored in a storage device as a function of time. Multiple points or multiple intervals of the time dependent data are used to direct a feedback mechanism to provide information or instruction in response to the time dependent output indicating too little activity, too much time with a joint not being moved beyond a specified range of motion, too many motions beyond a specified range of motion, or repetitive activity that can cause repetitive stress injury.

US Patent:

6871413, Mar 29, 2005

Filed:

Dec 15, 1997

Appl. No.:

08/990912

Inventors:

Steven W. Arms - Burlington VT, US
Christopher P. Townsend - Shelburne VT, US

Assignee:

Microstrain, Inc. - Williston UT

International Classification:

G01C009/06
G01B007/30

US Classification:

3336611, 33 1 N, 33 1 PT

Abstract:

The novel miniaturized inclinometer for angle measurement with accurate measurement indicator is designed to monitor the angular motion of limbs. The device contains at least one inclinometer with signal conditioning electronics, including a microprocessor, placed within a miniature housing. A number of different sensors can be used and positioned in their housings so that their outputs vary as a function of their angle with respect to the gravity sector. The microprocessor controls a multiplexer, which controls the activities of the sensors; performs analog to digital conversions and measures the output curves from the sensor pairs to perform a conversion which results in a three hundred and sixty degree range with respect to gravity. Calibration data is stored in a read only memory and the microprocessor corrects variables to ensure accuracy and measures the difference in angle between the pairs of sensors.