[54] LEARNING AND ASSESSMENT AID FOR A
`SEVERELY VISUALLY IMPAIRED
`INDIVIDUAL
`
`[75]
`
`Inventors: John Gesink, Kalamazoo; David Guth,
`Portage; Bernard Fehr, Okemos,all of
`Mich.
`
`[73] Assignee: Board of Trustees of Western
`Michigan University, Kalamzoo, Mich.
`
`[21] Appl. No.: 837,660
`
`[22]
`
`Filed:
`
`Apr. 22, 1997
`
`Tint, Cd ieeeccccsseeeccesssseesssssneeeeessies GO8B 13/00
`[51]
`[52] U.S. Che ce eeeeseeeeeee 434/112; 434/116; 704/271
`[58] Field of Search occ 434/112, 116;
`135/72; 704/271, 270; 367/116, 107
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`A learning and assessment aid (10) for helping visually
`impaired individuals develop desirable ambulatory motion
`habits. The learning aid includes a housing (14) designed to
`be attached to an article of clothing worn by the individual.
`Internal to the housing is an inertial transducer (16) that
`monitors the rotation of the housing and the individual. The
`7/1980 Hajduch.
`4,212,116
`individual enters commandsto the learning aid through a
`4,870,087—9/1989) DeLeon oc ceeeccecesesseeseeeeeees 367/116
`keypad (20) in response to audible instructions generated
`4,906,193
`3/1990 McMullenet al.
`.
`5,032,083
`7/1991 Friedman .
`over a speaker (22). To foster desirable turning motions, the
`5,032,836
`7/1991 Ono etal. .
`learning aid informs of the extent to which the individual
`5,097,856
`3/1992 Sheng ...cccccccsecesesceseseeees 135/72
`turns. To foster straight-line walking, the learning aid gen-
`5,120,228
`6/1992 Stahl et al.
`.
`erates a message over the speaker wheneverthe individual
`5,144,294
`9/1992 Alonzietal. .
`rotates more than a pre-set individual-entered maximum
`5,409,380
`4/1995 Balbuenaetal. .
`veer.
`5,470,233
`11/1995 Fructermanetal. .
`5,487,669=1/1996 Kelk wee ceecssceseneeeceeseneee 434/112
`5,508,699
`4/1996 Silverman .
`25 Claims, 13 Drawing Sheets
`
`United States Patent 55
`5,803,740
`Sep. 8, 1998
`[45] Date of Patent:
`Gesink et al.
`
`[11] Patent Number:
`
`US005803740A
`
`OTHER PUBLICATIONS
`
`Goldish, A Hand-Held Inertial Navigation Aid For The
`Blind Thesis, Massachusetts Institute of Technology, Apr.
`1965.
`
`LaDuke, The Veering Tendency of Blind Pedestrians: An
`Analysis of the Problem and Literature Review, Sep—Oct,
`1994, pp. 391-400.
`Cratty, Movement And Spatial Awareness In Blind Children
`and Youth, 1971, pp. 65-80.
`
`Primary Examiner—Richard J. Apley
`Assistant Examiner—Glenn Richman
`
`Attorney, Agent, or Firm—Flynn, Thiel, Boutell & Tanis,
`PC.
`
`[57]
`
`ABSTRACT
`
`
`
`
`
`APPLE 1014
`
`APPLE 1014
`
`1
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 1 of 13
`
`5,803,740
`
`
`
`2
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 2 of 13
`
`5,803,740
`
`2e
`
`FIG
`
`3
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 3 of 13
`
`5,803,740
`
`oS
`
`pfNS9Sa].SoS
`
`SOPESL
`“SMESSeA
`
` i
`a, Uett
`i4 Ay
` heNEOEEE
`A3
`
`erry} haeTas
`al
`
`a
`leahManaMeknnhe]
`
`52
`
`FIG.3
`
`4
`
`
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 4 of 13
`
`5,803,740
`
`FIG.4
`
`
`
`5
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 5 of 13
`
`5,803,740
`
`FIG.5
`
`FIG. 5A
`
`FIG. 5B
`
`6
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 6 of 13
`
`5,803,740
`
`
`
`7 VEER
`
`100
`
`PLD J]
`|
`+SYDC9
`GYROSCOPECommaye
`
`,
`
`PLD
`
`KEYPAD H}———]
`
`ENCODER
`
`98
`
`20
`
`SERIAL
`
`CNCTR
`
`118
`Txt
`SERIAL
`SERIAL
`
`
`
`
`
`FIG. 5A
`
`7
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 7 of 13
`
`5,803,740
`
`85
`
`/\ T\ss
`
`V
`
`87
`
`0+5VDC
`
`PLD,
`CNTRL
`
`cr
`
`14
`
`PLD,||PROCESSOR
`CNTRL
`SPEECH
`SYNTHESIZER
`
`ENCODER|_Toisecay [|_DISPLAY
`
`ON
`
`CNTR
`
`RST‘
`
`PSEN
`
`micro.
`
`SPCH
`
`LCNTRL
`
`
`
`06
`
`DRIVER
`
`108
`
`FIG.5B
`
`8
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 8 of 13
`
`5,803,740
`
`FIG. 6
`
`FIG.6A
`
`FIG.6C
`
`9
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 9 of 13
`
`5,803,740
`
`ACTIVATE
`AID
`
`130
`
`GENERATE
`WELCOME MSG
`
`132
`
`4\3
`
`136
`
`BATTERY
`CHECK
`
`\LOW]
`
`GENERATE LOW
`BATTERY MSG
`
`[38
`
`DEBUG > STRT
`]
`
`0]
`
`TRN
`
`42
`
`GENERATE
`
`REQUEST &
`
`RECEIVE
`MAX VEER
`
`160
`
`It
`
`(A)
`
`N
`
`TURN
`TEST
`CONFIRM
`
`162
`
`DIST
`
`(D)
`
`
`DISTANCE
`
`
`TEST
`
`TME
`
`REQUEST &
`
`164
`
`RECEIVE TEST DUR GENERATE
`
`INSTRUCTIONS
`
`14 » ©
` RDY CMND
`
`ENTER
`RDY CMND
`
`4b
`©)
`
`
`
`FIG.6A
`
`10
`
`

`

` GEN STRT SGNL
`
`
`
`
`
`
`
`
`
`
` 152
`
`
`
`168
`
`
`
`MONITOR
`VEER & TILT
`
`
`
`170 149
`
`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 10 of 13
`
`5,803,740
`
`GEN STRT SGNL
`CLR RGSTRS
`GYRO ON
`
`CLR RGSTRS
`GYRO ON
`
`148
`
`150
`
`MONITOR
`ROTATION
`
`ENTER
`STOP CMND
`
`GEN RSLTS
`GYRO OFF
`
`154
`
`REPEAT
`RESULTS
`
`11
`
`11
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 11 of 13
`
`5,803,740
`
`
`
`
`. 184
`
`
`
`
`[86
`
`ENTER RATE
`
`
`
`ENTER DSTNC
`
`ENTER
`RDY CMND
`
`
`GEN STRT SGNL
`CLR RGSTRS
`
`GYRO ON
`
`
` MONITOR
`
`VEER & TILT
`GYRO OFF
`
`
`
`
`
`GENERATE
`CNGRDLTRY MSG
`
`196
`
`GENERATE
`USER DATA
`
`20]
`
`12
`
`12
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 12 of 13
`
`5,803,740
`
`GENERATE
`INSTRUCTIONS
`
`ENTER
`RDY CMND
`
`GEN STRT SGNL
`CLR REGSTRS
`GYRO ON
`
`
`
`
`
`
`
`212
`
`214
`
`216
`
`218
`
`VEER & TILT
`
`
`
`
`STORE &
`DISPLAY DATA
`GYRO OFF
`
`GENERATE
`STOP CMND
`
`FIG. 7
`
`13
`
`13
`
`

`

`U.S. Patent
`
`Sep. 8, 1998
`
`Sheet 13 of 13
`
`5,803,740
`
`91
`
`8S°9l4
`
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`
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`
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`
`14
`
`14
`
`
`
`
`

`

`5,803,740
`
`1
`LEARNING AND ASSESSMENTAID FOR A
`SEVERELY VISUALLY IMPAIRED
`INDIVIDUAL
`
`FIELD OF THE INVENTION
`
`This invention relates to a learning and assessmentaid for
`an individual with a severe visual impairment and, more
`particularly, to a learning and assessment aid designed to
`provide information regarding the locomotion of the indi-
`vidual that can be used as a guideto foster desirable walking
`habits.
`
`BACKGROUND OF THE INVENTION
`
`An individual who is blind must use his/her senses to
`accomplish many of the activities of living that sighted
`persons take for granted. Two such activities related to
`pedestrian travel are those of walking in a desired direction
`and turning in a desired direction. Sighted individuals easily
`and accurately accomplish these activities on the basis of
`visual guidance. However, many individuals who are blind
`find these tasks difficult to accomplish accurately on the
`basis of nonvisual information. Therefore, a component of
`the instruction of a severely visually impaired or blind
`individual can include attempts to teach the individual to
`maintain a straight-line trajectory while walking and to
`make accurate turns, such as right angle turns one may wish
`to make at a street corner.
`
`This instruction requires both a means of assessing an
`individual’s ability to engage in such locomotion and a
`means for improving these abilities. One such learning
`system has the individual attempt to walk in a straight path
`and then requires the bending of a wire into the approximate
`shape of the path that the individual actually traversed. The
`individual then feels the wire to develop an impression ofthe
`extent his/her locomotion strayed from thestraightline path.
`One disadvantageis that it requires a sighted individual to
`accurately judge the walked path and to then bend the wire
`accordingly. This method further requires that the visually
`impaired individual be able to relate the small bent wire to
`his/her earlier walking trajectory.
`There have also been efforts to teach visually impaired
`individuals how to walk in a straight line by setting up in a
`lane in an open area that is bordered by optical beams.
`Sensors monitor the state of these beams. In the event the
`individual while walking movesto oneside or the other of
`the center of the lane, veering from straight line motion, the
`individual’s legs break one of the optical beams. The broken
`beam is detected by the complementary sensor which in turn
`generates a signal
`that causes the assertion of an audio
`alarm. Initially, the beams defining the lane may be spaced
`relatively wide apart. Over time, as the individual’s veer is
`reduced, the distance between the beam is reduced in order
`to further provide guidance for reducing an individual’s
`veer. A disadvantage of this system is that each time the
`lanes are set up, they need to be set up for the particular
`individual with whom they are to be used. Consequently,
`orientation and mobility instructors working with the blind
`individual must spend significant amounts of time aligning
`the beamsso that they can be used for a particular individual.
`Still another disadvantage of these training systemsis that,
`while they are useful for teaching a person to walk in a
`straight line, they are not well suited for providing guidance
`for helping a person learn how to turn.
`In the past, it has been proposed that persons could learn
`how to minimize their veer with the aid of an inertial motion
`
`sensor such a gyroscope. One such gyroscope proposed was
`
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`2
`designed to be held by an individual as he/shetries to walk
`along a straight line path-of-travel. If the individual veers
`rightor left from the straight line, a solenoid is energized so
`as to cause the extension of a small plunger; the tactile
`sensation of feeling the plunger extend serves as the indi-
`cation to the individual that he/she has veered from the
`desired straight line path-of-travel.
`While the previously proposed inertial motion sensor
`training device has shown promiseas an aid for training the
`blind,its utility is likewise limited. An individual using this
`device is required to walk with one of his/her armsin a bent
`position in order to be sure that
`the device is properly
`oriented and the individual can monitor the extended/
`retracted state of the plungers. Thus, in order to use this
`device the individual is require to walk in a mannerdifferent
`from which he/she would normally walk. Consequently, an
`individual using this device has to concentrate on more than
`just
`the skills required to walk in a straight
`line;
`the
`individual also has to devote some concentration to the
`
`muscle control required to properly hold the training device.
`Moreover, it would be difficult to use this device as an aid
`to walking in a straight line with a cane since the individual
`would have to perform two different, uncoordinated move-
`ments with his/her arms. Also,
`the previously proposed
`gyroscopic training device only provides an indication of
`veer once an individual’s movement exceeds a given angle.
`Still other limitations of the knowninertial sensor learning
`aid is that it does not provide an indication of the distance
`the individual has traveled andis not particularly useful for
`helping an individual learn how to execute turns.
`Moreover, as discussed above, a prerequisite to teaching
`an individual to develop desirable locomotion habits is the
`collection of baseline data about his/her initial locomotion
`habits. This informationis used by the instructor to evaluate
`the locomotion habits of the individual so that a training
`regime can be developed as well to serve as baseline data so
`that progress of the individual can be monitored. While the
`prior art learning aids are useful for helping an individual
`develop desirable locomotion habits, only with great diffi-
`culty can they be used to facilitate the collection of data
`about the individual requiring such training.
`
`SUMMARYOF THE INVENTION
`
`This invention relates generally to a new and useful
`learning and assessmentaid useful for helping an individual
`with a severe visual impairment develop appropriate loco-
`motion habits. The learning and assessmentaid is useful for
`collecting data regarding locomotion habits. The learning
`and assessment aid also provides a visually impaired indi-
`vidual with indications regarding his/her ability to both walk
`in a straight line and to execute turns. Moreparticularly, this
`invention relates generally to a learning and assessment aid
`that includes one or more inertial movement sensors that, at
`a minimum, provide an indication of the extent to which a
`personrotates his/her orientation from an initial heading. In
`one preferred version of this invention, a two-gimbal gyro-
`scope is employed as the inertial movement sensor.
`The learning and assessment aid of this invention is
`further designed so that the gyroscope or other sensor is
`contained in a small housing. The housing is provided with
`a pivoting clasp that allows the housing to be affixed to an
`article of clothing worn by an individualso as to ensure the
`properorientation of the sensor. The output signals produced
`by the sensor are applied to a digital signal processing unit.
`Based on the movementof the gyroscope, the digital signal
`processing unit determines the extent to which the housing
`
`15
`
`15
`
`

`

`5,803,740
`
`3
`has changed position. This measurementis used as the basis
`for providing an indication of the extent
`the individual
`wearing the learning and assessment aid has rotated from
`his/herinitial position. The learning and assessmentaid also
`has an alphanumeric display and a speech generator. The
`digital signal processing unit causes audio announcements to
`be generated that both instruct the individual how to set the
`device and that provide an indication of whether or not the
`individual has completed his/her intended movement.
`The learning and assessment aid of this invention is
`further configured to provide an indication of the total
`distance traversed by the individual. In someversionsofthis
`invention, this measurement is a time based-measurement
`that relates the time of use of the aid and the individual’s rate
`of travel to the distance traveled.
`Whenthere is a need to collect data about the locomotion
`
`habits of an individual, the aid is placed in the data collection
`mode. The aid generates a set of audible instructions direct-
`ing the individual to walk in a certain pattern, 1.e., straight-
`line or turn. The aid then collects data regarding the move-
`ment
`for a select period of time. Once the aid stops
`collecting data,
`the aid generates an audible command
`instructing the individual to stop moving. The data collected
`is then available to the instructor working with the indi-
`vidual.
`
`Whenthe learning and assessmentaid of this invention is
`used as a tool to foster straight-line movement, the indi-
`vidual can indicate the specific degree of veerthat is allowed
`before a warning tone is generated. The individual can also
`input an indication of the distance of travel over which the
`veer should be measured. The learning and assessmentaid of
`this invention can also be used as a tool to foster turning
`movement. Specifically, the individual can provide an indi-
`cation that he/she wants to practice turning. Then, once the
`individual completes a turn, the learning and assessmentaid
`will generate a message that provides an indication of the
`extent of the turn.
`
`Since this learning and assessment aid is worn on the
`body, once the instructions regarding the individual’s
`intended movementare entered, the individual can essen-
`tially ignore the presence of the aid. This allows the indi-
`vidual to focus his/her attention on the more important task
`at hand, executing the intended ambulatory movement.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`This invention is pointed out with particularity in the
`claims. The above and further advantages of this invention
`may be better understood by referring to the following
`description taken in conjunction with the accompanying
`drawings in which:
`FIG. 1 is a perspective view illustrating the inertial
`movementsensorlearning and assessmentaid of this inven-
`tion and illustrating how the aid is worn by an individual;
`FIG. 2 is a perspective view of the learning and assess-
`mentaid;
`FIG. 3 is a cross sectional side view of the leveling clasp
`of the learning and assessmentaid;
`FIG. 4 is a view illustrating the arrangement of the
`components inside the learning and assessmentaid;
`FIG. 5 is an assembly drawingillustrating how FIGS. 5A
`and 5B are assembled to form a schematic drawing of the
`electrical circuit integral with the learning and assessment
`aid;
`FIG. 6 is an assembly drawing illustrating how FIGS. 6A,
`6B and 6C are assembled to form a flow chart of the process
`
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`
`65
`
`4
`steps executed by the learning and assessment aid whenitis
`used to foster desirable locomotion habits;
`FIG. 7 is a flow chart of the process steps executed by the
`learning and assessmentaid of this invention whenitis used
`to collect data about the locomotion habits; and
`FIG. 8 is a schematic drawing illustrating an alternative
`transducer arrangementfor the learning and assessmentaid.
`DETAILED DESCRIPTION
`
`FIGS. 1+ illustrate a learning and assessmentaid 10 of
`this invention and how theaid is worn by a visually impaired
`individual 12. The learning and assessmentaid 10 includes
`a housing 14 in which the internal components of the
`learning and assessmentaid are enclosed. Inside the housing
`14 are a gyroscope 16 and a microprocessor 18. The gyro-
`scope 16 functions as an inertial movement sensor that
`produces signals representative of the shifting of the learn-
`ing and assessmentaid 10, as well as the individual wearing
`the learning and assessment aid, from an initial position. The
`microprocessor 18 receives signals based on those produced
`by the gyroscope 16 and,
`in response, generates output
`signals that provide an indication of the individual’s move-
`ment.
`
`As seen best in FIG. 2, secured to the outside of the
`housing 14 is keypad 20 through whichthe individual enters
`commands indicating the type of ambulatory movement
`he/she would like the aid to be monitoring. The learning and
`assessment aid 10 has a speaker 22 through which both
`audible instructions to the individual as well as information
`
`regarding how well he/she performed a specific ambulatory
`task are generated. Also on the outside of the housing 14 is
`a start button 24 which, as will be discussed hereinafter, is
`depressed as part of the initial actuation of the learning and
`assessment aid. A volume control 26 is provided for allow-
`ing the individual to control the audio level of the instruc-
`tions and messages generated by the speaker 22. Volume
`control 26 also controls the open-closed state of a main
`on/off switch. A display 28 is secured to the top of the
`housing 14. The display 28 is driven by the microprocessor
`18 to generate visual indications of the instructions required
`to operate the learning and assessment aid 10 as well as
`visual messages regarding how well
`the individual per-
`formed the tasks. A RS-232 data socket 29 is mountedto the
`
`side of the housing. The socket 29 providesa port that allows
`an external digital data processing device, such as a person-
`nel computer to exchange signals with the microprocessor
`18.
`
`The depicted learning and assessment aid 10 is also
`provided with a socket 30 for receiving a jack integral with
`an earphone. A socket 31 is also provided for shorting out a
`set of conductors connected to the microprocessor 18,
`(conductors not illustrated). When reprogramming of the
`microprocessor 18 is desired, a pin is inserted in socket 31
`to establish a connection between the conductors. The
`shorting out of the conductors is recognized by micropro-
`cessor 18 that it has been placed in a state for reprogram-
`ming.
`The learning and assessmentaid 10 is typically coupled to
`a belt 32 worn by the individual 12 using the aid, as seen by
`reference to FIGS. 1 and 3. This belt 32 can be either a belt
`
`specifically provided for the learning and assessment aid or
`a belt that the individual 12 would normally otherwise be
`wearing as an article of clothing. The learning and assess-
`mentaid 10 is attachedto the belt by a leveling clasp 34 that
`is secured to the back side of the housing 14. The leveling
`clasp 34 includes a back plate 36 that is the portion of the
`
`16
`
`16
`
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`

`5,803,740
`
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`
`15
`
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`5
`As can be seen in FIG. 4, the gyroscope 16 is itself housed
`clasp 34 that is actually secured to the back side of the
`in a foam shell 61. More particularly, the foam shell 61
`housing 14 with the aid of appropriate fasteners 38. A rigid
`includes a box-like main body 62 that is shaped to have a
`outer clasp plate 40 is flexibly secured at the top end thereof
`center void 64 in which the gyroscope 16 is nested. A
`to the back plate 36 bya strip of flexible material 41 such as
`separate rectangularly shaped piece of foam is fitted under
`a reinforced fabric or a flexible plastic strip. A rigid inner
`the main body 62 so as to serve as the base 65 of the shell.
`clasp plate 42 is attached to the top of the inner clasp plate
`In practice it has been found desirable to dimension the
`40 so as to be approximately in parallel alignment with the
`overall height of the foam shell 61 so that it is longer in
`outer clasp plate 40 and so as to project a small distance
`height than the space inside the housing 14 in whichit is
`below the bottom edge of the inner clasp plate. The inner
`seated. Thus, when the gyroscope 16 and shell 61 are seated
`clasp plate 42 is secured to the outer clasp plate 40 by a set
`in the housing,
`the subassembly is compression secured
`of fasteners 43 and washers 44 sothat the clasp plates 40 and
`42 are spaced a slight distance apart from each other. When
`inside the housing.
`the learning and assessment aid 10 is worn by the individual
`Twocircuit boards 66 are mounted in the housing 14 so
`12, the clasp plates 40 and 42 are fitted aroundthe belt 32.
`as to be located to one side of the gyroscope 16. The circuit
`To facilitate a snug fit, a leaf spring 45 is attached to the
`boards 66, which in the depicted version of the invention are
`surface of the outer clasp plate 40 that faces the belt 32.A
`vertically oriented, support the microprocessor 18 as well as
`layer of foam 47 is sandwiched betweenouterclasp plate 40
`many of the other electrical components integral
`to the
`and leaf spring 45 to provide resiliency to the leaf spring. A
`learning and assessment aid 10. In the depicted version of
`small rigid pin formed by a disk of metal 46 andaset of
`the invention, the electric components are mounted on the
`fasteners 48 is provided along the bottom edge of the inner
`circuit boards 66 so that the components face each other. A
`clasp plate 42. This pin is directed outwardly from the inner
`foam layer 68 is compression fitted between the electrical
`clasp plate 42. The pin is provided to minimize the possi-
`components so as to secure socketed components in the
`bility the leveling clasp 34 will inadvertently slip off the
`circuit board.
`complementary belt 32 over which the clasp is fitted.
`The leveling clasp 34 further includes a leveling plate 52
`that is hingedly secured to the bottom edge of the inner clasp
`plate 40. In the depicted version of the invention,the strip of
`material forming flexible material 41 extends the length of
`outer clasp plate 40 and connects leveling plate 52 to the
`inner clasp plate. The leveling plate 52 is secured to the
`bottom surface of the housing 14 so as to hold the housing
`in a particular, substantially level, orientation.
`In the
`depicted version of the invention, the leveling plate 52 and
`the bottom surface of the housing are provided with comple-
`mentary strips of fastening tape, 54 and 55, respectively, so
`as to facilitate the proper orientation of the housing. Fas-
`tening tape 54 and 55 allow leveling plate 52 to be selec-
`tively positioned relative to the bottom of housing 14. One
`such type of fastening tape that can be used to accomplish
`this task is sold under the trademark VELCRO.
`
`The electrical components not secured to the circuit
`boards 66 are attached to the main body 56 of the housing
`14. The display 28, is, for example, mounted in an opening,
`not identified, in the top of the main body 56. The display
`driver 108, the componentthat actuates the individual pixels
`of the display 28, is integrally manufactured with the display
`and as such, is suspended from the inside of main body 56.
`Speaker 22 is likewise secured to the inside of the top wall
`of the main body 56 of the housing 14.
`FIGS. 5A and 5B, when assembled, form a schematic
`diagram of the primary circuit components integral to the
`learning and assessmentaid 10 of this invention. As seen in
`these Figures, battery 72 provides the energy needed to
`operate the other components integral with the learning and
`assessmentaid 10. The positive terminalof battery 72 is tied
`to one end of a SPST switch 76 that functions as the main
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`poweron switch for the learning and assessment aid. Switch
`76 is the main on/off switch integral with the volumecontrol
`26. A ¥s Amp fuse 78 is attached to the opposed end of
`switch 76 to prevent excessively high currents from being
`applied to the other components of the learning and assess-
`ment aid 10.
`
`Housing 14 is provided with a cord 15 that can befitted
`around the neck of the individual 12 using the aid. Cord 15
`prevents the learning and assessment aid 10 from inadvert-
`ently being dropped.
`The housing 14, as seen in FIGS. 2 and 4 includes a main
`body 56 with sufficient depth to hold the gyroscope 16, the
`The energy provided by the battery 72 is applied through
`microprocessor 18 as well as most of the other components
`fuse 78 to a voltage regulator 80. The voltage regulator 80
`of the learning and assessmentaid. The main body 56 has an
`converts the battery voltage to a +5 VDC level suitable for
`open back endthat is enclosed by a cover 57. The cover 57
`energizing the other components of the learning and assess-
`is the portion of the housing 14 to which the leveling clasp
`ment aid 10. One such suitable voltage regulator is the
`34 is attached. The cover 57 is formed with a compartment
`53 in which the battery 72 (FIG. 5A) that powers the
`Maxim 639. In the depicted version of the invention, the
`battery voltage is applied from fuse 78 to voltage regulator
`learning and assessment aid 10 is housed. Threaded
`fasteners, not illustrated, secure the cover 57 to the main
`80 through an SCR 82. A bridge circuit consisting of
`
`body 56 of the housing 14. The threaded fasteners extend normally openstart button 24, a resistor 84 andaresistor 86
`55
`are tied from the anode of the SCR 82 to its cathode. The
`through holes 58 in the cover 57 and are coupled into
`threaded bores 59 formed in posts 60 integral with the main
`gate of the SCR 82 is tied to the junction of resistors 84 and
`86. When switch 76 is closed to enable activation of the
`body of the housing 14.
`learning and assessmentaid 10, SCR 82 is notin the onstate.
`Gyroscope 16, now discussed with reference to FIG. 4, is
`Therefore, there is no current flow through the SCR 82. In
`a two axis gyroscopic. One particular gyroscope from which
`this invention can be constructed is the Model GE9300C
`order to turn on the SCR 82 it
`is necessary to press,
`momentarily close, start button 24. This action causes a
`gyroscope manufactured by Gyration,
`Inc. of Saratoga,
`voltage to appear at the gate of the SCR 82 so as to turn on
`Calif. This gyroscope has an outer gimbal and complemen-
`the SCR. Current will then flow through the SCR 82 to the
`tary encoders that are used for measuring heading over a
`voltage regulator 80 until the current demand ofthe voltage
`360° range. The inner gimbal
`is pendulous,
`that
`is,
`it
`regulator ceases, as will be discussed hereinafter.
`stabilizes so as to be gravity aligned. Thus, any small
`deviations in tilting movement of the learning and assess-
`The output voltage produced by the voltage regulator 80
`ment aid are compensated for by the inner gimbal.
`is made available to the other components of the learning
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`5,803,740
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`7
`and assessmentaid through an inductor 84. A Shottky diode
`86 is connected between the output terminal of the voltage
`regulator 80 and ground as is required for proper operation
`of the voltage regulator. A capacitor 88 is tied between the
`end of the inductor 84 distal from the voltage regulator 80
`and ground. Collectively, inductor 84 and capacitor 88 filter
`the output energization signal produced by voltage regulator
`80 to minimize voltage variations in the supplied power. To
`minimize the complexity of FIGS. 5A and 5B, only the +5
`VDC powerterminals of the gyroscope 16 and micropro-
`cessor 18 are illustrated. The power connectionsto the other
`components to which the energization voltage produced by
`the voltage regulator 80 is applied are not illustrated.
`In the illustrated version of the invention, series con-
`nected resistors 90 and 92 are provided to form a voltage
`divider between the cathode of SCR 82 and ground. The
`voltage present at the junction of resistors 90 and 92 is
`applied to an input terminal of voltage regulator 80 as a
`LOW BATTERY INPUT (LBI) signal. In the event
`the
`LOW BATTERYINPUTsignalfalls below a specific level,
`voltage regulator 80 asserts a LOW BATTERY OUTPUT
`(LBO)signal to microprocessor 18. When microprocessor
`18 receives the LOW BATTERY OUTPUTsignal, it gen-
`erates appropriate audible warnings over speaker 22 and on
`display 28 to inform the individual using the device of the
`state of the battery 72.
`Voltage regulator 80 receives from microprocessor 18 a
`SHUTDOWN(SHDN)signal. As long as the SHUTDOWN
`signal, which is asserted low,is not received, voltage regu-
`lator 80 continues to produce an energization voltage for the
`other electrical components. Normally microprocessor 18
`does not assert the SHUTDOWNsignal. If, however, one of
`the buttons on the learning and assessmentaid keypad 20is
`not depressed after a given period of time, microprocessor
`18 asserts the SHUTDOWNsignal. Voltage regulator 80,
`upon receipt of the SHUTDOWNsignal, ceases to produce
`the energization voltage and stops drawing current through
`SCR 82. The cessation of current flow through the SCR 82
`turns off the SCR so as to stop current flow from the battery
`72. Thus, the assertion of the SHUTDOWNsignalturns off
`the learning and assessmentaid to prevent needless current
`drain of the battery 72. If the learning and assessmentaid 10
`is to again be used,all that is necessary to reactive it is to
`depress start button 24 so as to again turn on the SCR 82.
`Keypad 20 is a conventional 12-button telephone (“0”,
`“17,2. 49", “*” and “#”) keypad. The open/closedstates of
`the buttons of keypad 20 are monitored by a keypad encoder
`98 such as a 74C922. Depending on whichofthe buttons are
`depressed, keypad encoder 98 selectively asserts a parallel,
`4-bit signal to microprocessor 18.
`Gyroscope 16 produces two sets of pulsed quadrature
`output signals. A first set of signals are representative of the
`veer of the learning and assessment aid 10, the extent to
`whichthe learning and assessmentaid is rotated to either the
`left or the night in a horizontal plane. The second set of
`signals are representative of the tilt of the learning and
`assessment aid 10,
`the extent to which the learning and
`assessment aid pitches or rolls outside of a horizontal axis.
`Eachset of quadrature output signals is applied to a separate
`programmable logic device (PLD) that initially processes
`the signals. The veer quadrature signals are applied to PLD
`100. The tilt quadrature signals are applied to PLD 102.
`Altera EP600 programmable logic chips can be employed as
`PLDs 100 and 102.
`
`Each PLD 100 and 102 processes the quadrature signals
`received thereby to produce an output signal representative
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`of the incremental rotation of the learning and assessment
`aid 10. In an initial processing step, each PLD 100 or 102
`removesthe jitter from the received quadrature signals. This
`jitter occurs because the rotating disk internal to the gyro-
`scope produces minute vibrations that interfere with the
`make/break optical apparatus which producesthe quadrature
`signals. These vibrations introduce a small bounce, a jitter,
`into the high/low transitions of the quadrature signals. The
`PLDs 100 and 102 are configured to initially remove this
`jitter from the signals they receive.
`Once the PLD 100 or 102 removesthis jitter, the PLD
`performs its second processing step of generating a count
`representative of the incremental rotation of the learning and
`assessment aid 10. In the described version of the invention,
`the quadrature signals generated by the gyroscope 16 pro-
`vide a resolution to 0.2° of the rotation of the learning and
`assessment aid. Each PLD 100 and 102 contains a register
`in which an up/down count of the rotation of the learning
`and assessmentaid is maintained as represented bythe state
`of the received quadrature signals. The count maintained by
`PLD 100is representative of the incremental right/left veer
`of the learning and assessment aid. The count maintained by
`PLD 102is representative of the up/downpitch,thetilt, of
`the learning and assessment aid 10. As will be described
`hereinafter, these counts are periodically supplied to micro-
`processor 18.
`A dedicated clock 103 is provided for the PLDs 100 and
`102. Clock 103 generates a dedicated clock pulse signal to
`the PLDs 100 and 102 that facilitate their jitter removal and
`up/down count processing functions.
`In some preferred
`versions of the invention, clock 103 produces a 50 KHz
`signal with a 50% high cycle pulse.
`The speaker 22 is supplied with audio signals from a
`speech generator 1