US007292223B2
`
`(12) Unlted States Patent
`Suprun et a].
`
`(10) Patent N0.2
`(45) Date of Patent:
`
`US 7,292,223 B2
`*Nov. 6, 2007
`
`(54) LOCATION TRACKING DEVICE
`
`(56)
`
`References Cited
`
`(75) Inventors: Anton E. Suprun, Novosibirsk (RU);
`Dmitri V. Simonenko, Potomac Falls,
`VA (US)
`
`(73) Assignee: Innalabs Technologies, Inc., Dulles,
`VA(US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 689 days.
`
`Th1s patent 1s subJect to a term1nal d1s-
`claimer.
`
`(21) Appl. No.: 10/836,624
`
`(22) Filed:
`
`May 3, 2004
`
`(65)
`
`Prior Publication Data
`
`US 2005/0001814 A1
`
`Jan. 6, 2005
`
`Related US. Application Data
`
`(63) Continuation-in-part of application No. 10/442,170,
`?led On May 21, 2003, HOW Pat. NO. 7,061,469, which
`is a continuation-in-part of application No. 10/209,
`197, ?led on Aug. 1, 2002, noW Pat. No. 6,731,268,
`Which is a continuation of application No. 09/511,
`831, ?led on Feb. 24, 2000, noW Pat. No. 6,466,200.
`
`(51) Int, C],
`(200601)
`G09G 5/00
`(200601)
`G01C 21/00
`(52) us. Cl. .................... .. 345/156; 701/213; 701/215;
`
`7361408
`(58) Field of Classi?cation Search ...... .. 345/1564169-
`273/148 B; 463/37i38; 348/734; 73/51401i514'08:
`73/51431; 701/79, 110, 2134216; 342/357.06,
`342/357.07, 357.08, 357.12, 357.14
`See application ?le for complete search history.
`
`U'S' PATENT DOCUMENTS
`4,601,206 A
`7/19g6 Watson
`4,984,463 A
`1/1991 Idogaki et a1.
`5,181,181 A
`1/1993 Glynn
`5,774,113 A
`6/1998 Barnes
`5,831,553 A “H998 Lenssen et a1‘
`5,835,077 A 11/1998 Dao et al.
`A
`5,856,802
`*
`1/1999 Ura et al. ............ .. 342/357.08
`
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`DE
`
`3315958 A1
`
`1/1984
`
`(Continued)
`OTHER PUBLICATIONS
`
`English Translation Abstract t0 RU 2201618 C2 (ALl).
`
`(Continued)
`_
`Primary ExamineriLun-Yl Lao
`(74) A210" "e24 Agent! 0'’ FirmiBardmesser Law Group
`
`(57)
`
`ABSTRACT
`
`A location tracking device utilizing an acceleration sensor is
`described. The acceleration sensor includes an inertial body
`in magnetic ?uid that is contained in a closed volume vessel.
`The tracking device may be used for tracking Objects,
`people, animals, and the
`The tracking device may be
`utilized as a back-up system to a GPS system such that When
`Signal from a GPS receiver are unavailable’ the location
`tracking 'device may provide positional information about
`‘he 1mm“ Ofthe Oble“
`
`19 Claims, 3 Drawing Sheets
`
`10
`
`MAGNETIC
`FIELD
`scuRcE
`
`CURRENT
`eauzanm
`
`muuc'nou
`con
`
`CONTROLLER
`
`REGISTER
`
`3“
`
`SERIAL
`INTERFACE
`
`35
`
`“7
`
`SIGNAL
`COVERTER 38
`MODULE
`
`LE EL
`CONVERTER
`
`I
`
`M
`
`‘ /
`l
`
`DEV“
`
`Exhibit 2007
`
`

`

`US 7,292,223 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`5,905,460
`5,982,169
`6,002,184
`6,128,006
`6,154,199
`6,160,540
`6,369,794
`6,466,200
`6,501,458
`6,509,888
`6,731,268
`6,820,002
`6,924,764
`6,985,134
`7,061,469
`2002/0003527
`2002/0054011
`2004/0095317
`2004/0140962
`
`5/1999
`A *
`A 11/1999
`A 12/1999
`A 10/2000
`A 11/2000
`A * 12/2000
`B1
`4/2002
`B1
`10/2002
`B2 12/2002
`B1
`1/2003
`B2 *
`5/2004
`B2 * 11/2004
`B1 *
`8/2005
`B2 *
`1/2006
`B2 *
`6/2006
`A1
`1/2002
`A1
`5/2002
`A1
`5/2004
`A1
`7/2004
`
`Odagiri et al. ....... .. 342/357.06
`Furlani et al.
`Delson et al.
`Rosenberg et al.
`Butler
`Fishkin et al. ............ .. 345/184
`Sakurai et al.
`Anton et al.
`Baker et al.
`Tuovinen et al.
`Anton et al. .............. .. 345/163
`
`Terada ...... ..
`
`701/207
`
`342/357.07
`Chen ........ ..
`345/163
`Suprun et al.
`Suprun et al. ............ .. 345/158
`Baker et al.
`Bruneau et al.
`Zhang et al.
`Wang et al. .............. .. 345/179
`
`FOREIGN PATENT DOCUMENTS
`
`JP
`JP
`JP
`JP
`JP
`RU
`RU
`RU
`RU
`
`62-163972
`02-205775
`04-344467
`06-3444467
`06-213921
`2168201 C1
`2166203 C1
`2173882 C1
`2201618 C2
`
`7/1987
`8/1990
`12/1992
`12/1992
`8/1994
`11/1999
`1/2000
`3/2000
`3/2001
`
`OTHER PUBLICATIONS
`
`English Translation Abstract to RU 2168201 C1 (AOl).
`“IEEE Recommended Practice for Precision Centrifuge Testing of
`Linear Accelerometers”, IEEE Standards 836-2001, The Institute of
`Electrical and Electronics Engineers, Inc., Nov. 7, 2001, pp. i-86.
`“IEEE Speci?cation Format Guide and Test Procedure for Two
`Degree-of-Freedom Dynamically Tuned Gyros”, ANS/IEEE Std
`813-1988, The Institute of Electrical and Electronic Engineers, Inc.,
`1989, pp. i-91.
`Bashtovoi, V.G. et al. “Introduction to Thermomechanics of Mag
`netic Liquids”, High Temperature Institute of the Academy of
`Sciences of the USSR, Moscow, 1985 (partial translation of p. 13).
`“IEEE Standard Speci?cation Format Guide and Test Procedure for
`Nongyroscopic Inertial Angular Sensors: Jerk, Acceleration, Veloc
`ity, and Displacement”, IEEE Std 671-1985 (R2003), The Institute
`of Electrical and Electronics Engineers, Inc., 1985, pp. iii-69.
`English Translation Abstract for DE 3315958 A1, 1 page, supplied
`from the esp@cenet database.
`Noti?cation Of Transmittal Of T he International Search ReportAnd
`The Written Opinion Of The International Searching Authority, Or
`The Declaration, from PCT Application No. PCT/US04/ 15924, 8
`pages, mailed Dec. 9, 2004.
`Computer Internet Website, Magellan 3D Controller (also known as
`Space Mouse), by Logicad, a Logitech Company, address “http://
`WWW.qualiXdirect.com/html/magellan.html”, 2 pages.
`Computer Internet Website, “Logitech 3D Mouse Logitech Head
`Tracker”, by Fakespace, Inc., address “http://WWWqualiXdirect.
`com/html3dimouseiandiheaditrackerhtml”, 2 pages.
`Computer Internet Website, “The Spaceball 3D Controller”, by
`Spacetec IMC Corporation, address “http://WWWqualiXdirectcom/
`html/spaceballhtml”, 3 pages.
`
`English Translation Abstract to RU 2173882 C1 (AM1).
`English Translation Abstract to RU 2166203 C1 (AN1).
`
`* cited by examiner
`
`Exhibit 2007
`
`

`

`U.S. Patent
`
`Nov. 6, 2007
`
`Sheet 1 of3
`
`US 7,292,223 B2
`
`10
`
`MAGNETIC
`FIELD
`SOURCE
`
`CURRENT
`GENERATOR
`
`I
`
`INDUCTION
`COIL
`
`W
`(
`28
`
`I
`'
`
`ACCELERATION
`SENSOR
`
`Um
`
`U21
`
`Uy1
`
`UXZ
`
`U22
`
`122
`
`V
`
`Y
`
`CONTROLLER <
`
`J
`ADC
`
`I
`
`v
`
`i 3
`
`w14
`V32
`30
`
`1
`
`SWITCH
`
`+ REGISTER
`
`H "
`
`SWITCH
`
`34
`
`SERIAL $36
`INTERFACE
`
`40
`
`SIGNAL
`COvERTER 38
`MODULE
`
`+
`‘'
`LEvEL
`CONVERTER <
`
`44
`30
`LOCATION L
`POSIETIIOSIEINC
`
`>
`
`FIG. 1
`
`‘RA-‘U- DISPLAY
`
`Exhibit 2007
`
`

`

`U.S. Patent
`
`Nov. 6, 2007
`
`Sheet 2 of3
`
`US 7,292,223 B2
`
`FIG. 2
`
`Exhibit 2007
`
`

`

`U.S. Patent
`
`Nov. 6, 2007
`
`Sheet 3 0f 3
`
`US 7,292,223 B2
`
`52
`
`GPS
`receiver
`
`Switch w 54
`
`16
`
`i
`Location
`Positioning
`Device
`
`FIG. 3
`
`Exhibit 2007
`
`

`

`US 7,292,223 B2
`
`1
`LOCATION TRACKING DEVICE
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a continuation-in-part of US. patent
`application Ser. No. 10/442,170, ?led May 21, 2003 Which
`is a continuation-in-part of US. patent application Ser. No.
`10/209,197, ?led Aug. 1, 2002 Which is a continuation of
`US. patent application Ser. No. 09/511,831, Feb. 24, 2000
`now US. Pat. No. 6,466,200, Which in turn claims priority
`to Russian patent application No. 99122838, ?led Nov. 3,
`1999, each of Which are incorporated by reference herein in
`their entireties.
`
`FIELD OF THE INVENTION
`
`The invention is directed to using an acceleration sensor
`as part of a location tracking device for providing positional
`information about the objects movement and location.
`
`20
`
`SUMMARY OF THE INVENTION
`
`Accordingly, the invention may include a location track
`ing device Which may include an acceleration sensor that
`preferably includes a closed volume vessel containing mag
`netic ?uid, a non-magnetic inertial body contained in the
`vessel, and at least three magnetic ?eld sources located in
`pairs on three mutually perpendicular axes around the closed
`volume vessel. In preferred embodiments, the at least three
`magnetic ?eld sources have an output connected to inputs
`for the signal converter module. The invention may include
`a location positioning device, Where the outputs of the signal
`converter module are connected to inputs of the location
`positioning device.
`The invention may also include a location tracking device
`Which may include a GPS apparatus and an acceleration
`sensor, Where the acceleration sensor may include a closed
`volume vessel containing magnetic ?uid, a non-magnetic
`inertial body contained in the vessel, and at least three
`magnetic ?eld sources located in pairs on three mutually
`perpendicular axes around the closed volume vessel. The at
`least three magnetic ?eld sources have an output connected
`to an input of a signal converter module. The device may
`include a location positioning device and a sWitch in com
`munication With the GPS apparatus, the signal converter
`module, and the location positioning device, Where the
`sWitch provides GPS positional information to the location
`positioning device and monitors GPS signals from the GPS
`apparatus and based on an interruption of the GPS signal,
`provides positional information from the signal converter
`module to the location positioning device.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a diagrammatic vieW of a location positioning
`device in accordance With an embodiment of the invention;
`FIG. 2 is a diagrammatic vieW of a location positioning
`device in accordance With another embodiment; and
`FIG. 3 is a diagrammatic vieW of a location positioning
`device in accordance With yet another embodiment.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`In accordance With an embodiment of the invention, a
`location tracking device is provided With an acceleration
`
`2
`sensor that alloWs for three dimensional manipulation and
`detection of movement in as many as six degrees of free
`dom. The acceleration sensor provides increase reliability
`and manufacturability and provides the capability of gradual
`sensitivity adjustments. As Will be discussed beloW, the
`location tracking device and system may be used for track
`ing various assets, such as inventory items, personnel,
`equipment, and other items Where the location of the item is
`important to knoW.
`Various embodiments of the location tracking device and
`system utiliZe an acceleration sensor, With reference noW to
`FIG. 1, there is shoWn a location tracking device 10 in
`accordance With an embodiment of the present invention.
`Generally, the location tracking device 10 includes an accel
`eration sensor 12, a signal converter module 14, and a
`location positioning device 16. Brie?y, With the acceleration
`sensor 12 ?xed to a object, the acceleration sensor 12 detects
`the movement of the object and sends signals through the
`signal converter module 14 to the location position device
`16 Where the location of the object is determined.
`The acceleration sensor includes a symmetric inertial
`body 18 made of non-magnetic material positioned in a
`closed volume vessel 20 containing magnetic ?uid 22. In
`certain embodiments, three pairs of magnetic ?eld sources,
`each represented by the reference numeral 24, are located
`around the closed volume vessel 20 on mutually perpen
`dicular axes.
`The inertial body 18 includes a symmetrical shape, such
`as a sphere or a centrally symmetrical polygon, and is made
`of non-magnetic material such as plastic or Plexiglas. The
`inertial body 18 is surrounded by the magnetic ?uid 22 in the
`closed volume vessel 20. The shape of the inertial body is
`not particularly limited and may include a spherical or a
`centrally symmetrical polygon. Further, the inertial body
`may be relatively solid or holloW. The inertial body may
`consist of tWo or more non-magnetic materials. In some
`embodiments, the inertial body may have a density close to
`that of the selected magnetic ?uid.
`The closed volume vessel 20 holds the magnetic ?uid 22
`and symmetric inertial body 18 Within the interior space of
`the closed volume vessel. The shape of the closed volume
`vessel is not particularly limited and can take on a variety of
`shapes, such as spherical or a centrally symmetrical poly
`gon. In some embodiments, it is preferable to that the closed
`volume vessel 20 be centrally symmetric.
`The magnetic ?uid 22 is contained Within the closed
`volume vessel 20. The acceleration sensor is based on the
`properties of the magnetic ?uid. Expulsive forces are devel
`oped around a non-magnetic body immersed in magnetic
`?uid. The potential and distribution of the magnetic ?eld
`lines in the magnetic ?uid determine the direction and
`magnitude of such expulsive force. (S. V. Rulev, V. N.
`Samsonov, A. M. Savostianov, G. K. Shmyrin, “Controlled
`Vibroinsulators With Magnetic Fluid”, MO USSR, M., 1988,
`pages 17-21, herein incorporated by reference in its
`entirety).
`Therefore, the magnetic ?uid should be vieWed relative to
`the body made of the non-magnetic material as an environ
`ment Which the effective density is increased proportionately
`to the increase of the magnetic ?eld force.
`In some embodiments, the magnetic ?uid may be a
`tWo-phase system that possesses both ?oWability and high
`sensitivity to an applied magnetic ?eld. The particle siZe of
`the solid phase of the mixture in one embodiment may be
`about 1><10_9 meters. One type of suitable magnetic ?uid is
`a loW viscosity dispersion of magnetite or loadstone in
`kerosene, having a density ranging from about 1.1 to about
`Exhibit 2007
`
`

`

`US 7,292,223 B2
`
`3
`1.5 grams/cubic centimeter. The kerosene dispersion has an
`effective viscosity ranging from about 0.005 and about 0.1
`PAs and has magnetiZability under a 250 kA/m magnetic
`?eld betWeen about 30 and about 50 kA/m.
`Another suitable magnetic ?uid may include a loW vis
`cosity dispersion of magnetite in liquid organic silicone
`having a density ranging from about 1.1 and about 1.5
`grams/cubic centimeter. The silicon dispersion has an effec
`tive viscosity beloW about 0.7 PAs and has a magnetiZability
`under a 250 kA/m magnetic ?eld of about 25 kA/m. Further,
`a magnetoreactic suspension of dispersed ferromagnetic
`matter in liquid organic silicone may serve as a suitable
`magnetic ?uid. The magnetoreactic suspension has a density
`ranging from about 3.4 to about 4.0 grams/cubic centime
`ters, a friction of factor of about 0.1 to about 0.2, and a Wear
`rate ranging from about 2><10_7 to about 8><10_7.
`With continuing reference to FIG. 1, the magnetic ?eld
`sources 24 are located around the closed volume vessel 20.
`In some embodiments three pairs of magnetic ?eld sources
`24 are spaced around the closed volume vessel 20 on
`mutually perpendicular axes (note that only ?ve of the six
`sources are shoWn in the ?gure). The magnetic ?led sources
`24 include a current generator 26 and one or more induction
`(magnetic) coils 28, Where the current generator 26 may be
`serially connected to the induction coils 28. In some embodi
`ments one current generator 26 is used for all induction coils
`28 or alternatively, each induction coil 28 or pair of induc
`tion coils may have their oWn current generator 26. In order
`to simplify the device’s manufacturing, additional sources of
`the magnetic ?eld may consists of several interconnected
`coils. In order to reduce poWer consumption, one or more
`constant magnets may be added to the source of magnetic
`?eld. Further, several additional magnetic ?eld sources may
`be introduced in the device. The outputs from these addi
`tional sources may be optionally connected.
`A signal converter module assembly 14 and optional
`sWitches 30 are provided Where the magnetic ?eld source 24
`is connected to current generator 26 and induction coil 28,
`and Where the current generator is connected to the magnetic
`?eld source 24. The signal converter assembly 14 may
`contain a six-channel analog to digital converter ADC 32, a
`controller 34, a serial interface 36, a level converter 38 and
`an input register 40, Where the input register inputs are
`digital inputs of the signal converter module 14 and analog
`inputs of the signal converter module 14 are inputs of the
`ADC 32. In some embodiments, the ADC output is con
`nected through bi-directional bus With the controller 34,
`input register 40 and serial interface 36, the input and output
`of Which are correspondingly connected to the output and
`input of the level converter 38. In some embodiments, the
`output and input of the level converter is the device output
`and inputs. The outputs for the acceleration sensor 12 are
`connected to the analog inputs of the signal converter
`module 14, and the digital inputs are connected to optionally
`provided sWitches 30, Where one of the sWitches may be
`employed as an indicator of the operator activity and
`remaining sWitches are used by the operator to control
`softWare on a computer.
`Analog outputs of the signal converter module 14, Which
`are outputs of a six channel ADC 32, are connected to the
`control terminals of the magnetic ?eld sources 24, Which are
`inputs of the current generator 26. Digital inputs to the ADC
`32 are connected by a bi-directional bus With the controller
`34.
`The induction (magnetic) coil(s) 28 may be connected to
`a parallel resonance circuit in order to register changes in the
`coil’s Q-factor, to be discussed beloW. Various designs of
`
`50
`
`55
`
`60
`
`65
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`4
`adjustable voltage current generators for the current genera
`tor 26 on transistors or operational ampli?er IC are
`described in P. HorovitZ, W. Hill “The Art of Circuit Engi
`neering”, 3 volumes, published in MoscoW by Mir in 1993,
`herein incorporated by reference in its entirety.
`The signal converter module 14 may be based on a
`MC68HC05B6 chip or other similar chip, With serial input
`and output connected correspondingly to the output and
`input of the level converter 38, Which can be designed
`around an ADM203 chip. The MC68HC05B6 is an 8-bit
`single chip microcontroller that contains HCO5 micropro
`cessor core, 6 Kbyte ROM, 176 byte RAM, 8-channel, 8-bit
`ADC With built-in reference voltage generator, multipurpose
`timer, clock generator Which requires external quartZ reso
`nator and passive ?lter, and RS-232 serial interface. The
`serial interface is an example but could be any communi
`cation method that permits processor to processor commu
`nication, Connection diagram and detailed description of
`this microcontroller can be found in “MC68HC05B6 Tech
`nical Data” Rev. 3 1995.
`An AD7228A chip may be used as a 6-channel ADC in
`signal the converter module 14. The AD7228A has a built-in
`reference voltage generator, and requires single +5V poWer
`source. To create additional analog inputs in the signal
`converter assembly, one or more AD 7828 chips may be
`employed as an 8 channel, 8-bit ADC. They require a +5V
`poWer source and a ?ltered +5V poWer source may be used
`as reference voltage. Technical speci?cations of AD7228A
`and AD 7828 may be found in 1996 Short Form Designer
`Guide, Analog Devices, 1996 herein incorporated by refer
`ence in its entirety.
`The ADM203 chip has tWo channels of logical signal
`converter With 0 and +5V levels in RS-232 signals ands tWo
`converter channels from RS-232 into 0 and +5V logical
`signals. No passive elements are required. Technical speci
`?cations and connection diagrams of ADM203 chip may be
`found in ADMZXXL Family for RS-232 Communications,
`Rev. 0, 1994 and is here in incorporated by reference in its
`entirety.
`To provide for gradual sensitivity adjustment by computer
`softWare, a DAC may be added to the signal converter
`module 14. In this con?guration, the DAC output Would be
`connected to the analog output of the signal converter
`module 14, Which connects to control inputs of the magnetic
`?eld sources 24. The DAC may be connected by a bi
`directional bus to the controller 34. The control input of the
`magnetic ?eld sources 24 is the control input for the current
`generator 26.
`The location positioning device 16 receives signals gen
`erated from the acceleration sensor 12 and signal converter
`module 14 and uses the signals to determine the location of
`the object. Location positioning device 16 may include a
`computer 42 With associated softWare or programming that
`use the signals from the acceleration sensor 12 and signal
`converter module 14 to track the location of the object. In
`some embodiments the location positioning device 16
`includes reference location information, such as a map or
`other similar reference information. The location positioning
`device 16 may use the signals generated from the accelera
`tion sensor 12 and signal converter module 14 to compare
`the movement of the object With the reference location
`information to determine the location of the object. The
`location positioning device 16 may include a display 44 that
`displays the location of the object and may also display the
`reference location information.
`
`Exhibit 2007
`
`

`

`US 7,292,223 B2
`
`5
`The general operation of a location tracking device in
`accordance With an embodiment of the invention Will noW
`be described.
`Due to the radial gradient of the magnetic ?eld force, the
`effective density of the magnetic ?uid increases in the
`direction from the center of the acceleration center. There
`fore, the inertial body is being pushed toWard the equilib
`rium point that is close to the geometric center of the
`acceleration sensor.
`After the acceleration sensor is moved, the inertial body,
`being in transitional state, is moved aWay from the equilib
`rium center, Which in turn leads to the change in thickness
`of magnetic ?uid located underneath each coil.
`The alternating magnetic ?eld of each coil interacts With
`a volume part of magnetic ?uid adjacent to it; Where this
`volume fraction is determined by the distribution of the
`magnetic ?eld lines, and the depth of the volume fraction is
`determined by the inertial body position.
`The quantity and properties of the magnetic ?uid in the
`fraction of the volume directly relates to and determines the
`amount of energy needed for ?ux reversal magnetiZation of
`the magnetic ?uid.
`The Q-factor of the coil can noW be measured by the
`amount of energy spent on alternating the magnetic ?eld,
`Which depends on the amount of magnetic ?uid in the
`affected volume fraction, Which in turn depends on the
`position of the inertial body in the sealed container. The
`inertial body is displaced due to acceleration caused by
`movement of the acceleration sensor. As displacement
`occurs, the Q-factor of each coil changes as the inertial body
`moves aWay from the equilibrium point.
`Additionally, the image impedance of the electric magnet
`(each coil) Will change accordingly. The impedance change
`leads to a change of voltage on the electrical magnets (coils),
`Where amplitudes of the potential Will change in antiphase
`on the coils on Which the axis force is applied to the
`acceleration sensor. After the movement of the sensor, the
`dilferential of the current (amplitude) variable component
`increases in each couple of coils and is proportional to the
`acceleration applied to the corresponding axis. It is the
`possible to describe the movement of the sensor along any
`space trajectory.
`When the sensor is being rotated along the axis, the
`magnetic ?uid acts as an inertial body, Which moves in the
`magnetic ?eld. The magnetic ?eld is inhomogeneous in the
`direction of the rotation. Acceleration in the ?oW of the
`magnetic ?uid resulting from the rotation leads to a change
`in impedance in the electric coils for these coils along Which
`the magnetic ?uid is moving. Such change in impedance,
`Which results from a loss of magnetic ?eld energy to reversal
`magnetiZation of moving magnetic ?uid, leads to in-phase
`change coils voltage. The magnitude of the voltage change
`is proportionate to angular acceleration of the acceleration
`sensor. Therefore, the magnitude of the voltage change is
`used to describe the axial rotation of the acceleration sensor
`at any axis.
`The device of the present invention provides for indepen
`dent sensing of movement along three spatial and three
`angular degrees of freedom. The device output signal con
`tains information about six independent degrees of freedom.
`Reliability of the device is increased by the absence of the
`contacting mechanical parts and ease of manufacture is
`increased by the absence of the requirements for precision
`machining of the acceleration sensor parts. Many of the parts
`may be manufactured by injection molding from plastic.
`Electrical magnets may be manufactured by the printed
`
`20
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`circuit technology in order to eliminate need for coiled parts
`to further simplify the device manufacturing.
`Sensitivity adjustment of the input device may be
`achieved by changing the medial potential of the magnetic
`?eld in the magnetic ?uid. A change in the magnetic ?eld can
`be either due a to change of current in the coils or a change
`in proximity of the magnetic ?eld sources from the surface
`of the acceleration sensor.
`The proposed input device may be used for input of
`coordinate information, graphical information and control
`ling computer generated objects, Which may be valuable in
`such computer applications as computer games and 3-di
`mensional designs, etc., and as a substitute for a mouse,
`keyboard or the like.
`With reference to FIG. 1, the folloWing symbols are used:
`The folloWing symbols are used: Uxl, U?ivoltages on the
`acceleration sensor output that corresponds to the X axis;
`Uyl, Uy2ivoltages on the acceleration sensor output that
`corresponds to the Y axis; U21, Uzzivoltages on the accel
`eration sensor output that corresponds to the Z axis.
`While the device is not in motion, the non-magnetic
`inertial body 18 is located near the center of the magnetic
`?uid ?lled vessel 20 of the acceleration sensor 12. This
`position of the inertial body creates a magnetic ?eld in the
`magnetic ?uid 22. The intensity of the magnetic ?eld
`increases aWay from the center of the vessel of the accel
`eration sensor 12, Which ensures positive gradient of effec
`tive density of the magnetic ?uid 22 that is also directed
`aWay from the sensor center. Therefore the inertial body 18,
`not being in?uenced by the magnetic ?eld, is displaced to
`the point of loWest e?fective density of the magnetic ?uid 22,
`to the proximity of the geometrical center of the magnetic
`?uid 22 ?lled volume of the acceleration sensor 12.
`A symmetric (e.g. sphere) shaped inertial body that is
`enclosed in magnetic ?uid ?lled volume ensures approxi
`mate equal thickness of the magnetic ?uid betWeen the
`inertial body and the magnetic ?eld sources 24. The mag
`netic ?eld source consists of the current generator 26 and
`coil 28. In order to register coils Q-factors, the current
`generator 26 output contains an alternating current (AC)
`component. The amplitude of the alternating component for
`each generator is less than the DC component agents,
`generator output may entirely consists of (in the design
`version With constant in alternating component to reduce
`poWer consumption). The amplitudes of alternating compo
`nent for each current generator 26 are approximately equal.
`Thickness of the magnetic ?uid layer is nearly equal
`relative to each of the magnetic coils 28 on the X and Y axis
`Which ensures fairly good uniformity of Q-factors on all the
`coils 28. Therefore, alternating current voltages in the static
`state of the device are approximately equal on the accelera
`tion sensor 12 outputs responsible for the X and Y-axis. As
`Will be seen in the formulas beloW, since actual values of
`“static” voltages on corresponding coils are used, then the
`difference in Q-factor values resulting from mechanical
`imperfections or mal-adjustments in the sensors may be
`ignored, as they do not affect accuracy. Therefore a differ
`ences in Q-factor of the coils on the Z-axis due to offset of
`the inertial body 18 on this axis do not result in inexact
`acceleration measurement on the Z-axis.
`Acceleration sensor sensitivity adjustments are achieved
`by changing the medial level of magnetic ?eld in the
`magnetic ?uid. The change can be made by changing the DC
`component magnitude on the current generator or by
`decreasing/increasing the magnetic source proximity from
`the center of the accelerator sensor.
`
`Exhibit 2007
`
`

`

`US 7,292,223 B2
`
`7
`A change in the DC component may be controlled by a
`computer through the input of the device by changing the
`voltage on the DAC output and therefore controlling the
`current generator. There are tWo Ways to adjust the accel
`erator sensor. First, the acceleration sensor may be adjusted
`independently from the computer softWare by changing the
`proximity of the magnetic ?eld sources relative to the center
`of the acceleration sensor or by manually changing the DC
`component of the current generators. Second, the accelera
`tion sensor may be adjusted by computer commands that
`change the voltage on the analog outputs of the signal
`converter.
`The inertial mass damping coe?icient of the magnetic
`?uid changes as a result of moving aWay from an equilib
`rium state. The damping coe?icient determines the ampli
`tude (gain)-frequency response by the magnitude of the
`inertial mass displacement from the equilibrium state under
`a speci?ed acceleration level applied to the acceleration
`sensor. Therefore the range of the magnetic ?uid thickness
`change is being measured relatively to each of the magnetic
`?eld sources, Which is in turn determines the range of
`reactance change on the coil. Thus the adjustment of change
`in the amplitude of the alternating component on the outputs
`of the acceleration sensor takes place.
`In order to match the dynamic range changes in output
`voltage of the acceleration sensor to the ?xed range of the
`ADC microcontroller in the signal converter assembly, it
`may be necessary to serially connect a six channel AC
`ampli?er on the inputs of the ADC microcontroller. Such an
`ampli?er may be designed as an active ?lter. In order to
`reduce precision machining requirements to the assemblies
`and parts of the acceleration sensor and to provide for
`adjustable ampli?er channels in ADC, actual voltages on the
`acceleration sensor in the stationary state may be recorded
`into controller after being converted into the digital state by
`the ADC.
`Input data from the device to the computer may occur
`according to the folloWing example: When the sWitch indi
`cating operator activity is engaged, and movement of the
`device by the operator’s hand caused acceleration along the
`X-axis, the inertial body Will move to the left from the
`equilibrium position and the thickness of the magnetic ?uid
`under the left coil Will decrease and increase under the right
`coil.
`As a result of the affected volume changes, both Q-factor
`and alternating current voltage of the right coil Will decrease.
`Based on measurements of the AC change in the X-axis
`coils, acceleration can be quanti?ed. Signals from the accel
`eration sensor, after being digitiZed by the ADC directed to
`the controller, Where X axis acceleration is estimated as
`folloWs:
`
`45
`
`50
`
`In Formula 1, p is a factor determined by the geometric
`dimensions of the acceleration sensor and the magnetic ?uid
`properties under a constant magnitude of the magnetic ?eld
`DC component in the magnetic ?uid.
`Un- is the momentary magnitude of the AC component on
`the “i” number of output terminal of acceleration sensor,
`Which corresponds to the X axis; and UxlO is the amplitude
`of the AC component on the “i” number of output terminals
`of the acceleration sensor, Which corresponds to the X-axis
`in the stationary state of the device.
`Acceleration components ay and a2, Which correspond to
`the Y and Z-axis are determined in the manner consistent
`With Formula 1.
`
`55
`
`60
`
`65
`
`20
`
`25
`
`30
`
`35
`
`40
`
`8
`In Formula 1, P is factor determined by the geometric
`dimensions of the acceleration sensor (1) and the magnetic
`?uid properties (3) under a constant magnitude of the
`magnetic ?eld DC component in the magnetic ?uid (3);
`Uyl. is the momentary amplitude of the AC component on
`the “i” number of output terminals of the acceleration sensor
`(1), Which corresponds to the Y axis; and
`Uyl-O is the amplitude of the AC component on the
`number of output terminals of the acceleration sensor (1),
`Which corresponds to the Y-axis in the stationary state of the
`device.
`Angular acceleration 1px, Which describes the rotation
`around the Y-axis, is determined by Formula 2:
`
`wXIPX [(Uy1—Uy1°)+(Uy2—Uy2°)]
`
`(Formula 2)
`
`Ipy, 1P2 are determined in a similar manner.
`Because relationship lp?lyl, Uylo, Uyz, Uy2o) has cyclical
`properties With a cycle of 180°, unambiguous solutions of
`the