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`SAMSUNG EXHIBIT 1006
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`U.S. Patent
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`140
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`Apr. 13, 2010
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`Sheet 1 of 3
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`US 7,698,097 B2
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`U.S. Patent
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`Apr. 13, 2010
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`Sheet2 of 3
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`US 7,698,097 B2
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`140
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`U.S. Patent
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`Apr. 13, 2010
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`Sheet 3 of 3
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`US 7,698,097 B2
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`Nye= Nyytt
`
`Nyc = min(O, Nyg - 2)
`
`Aan
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`Fig.5
`
`
`
`Ta(1)
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`Ta(2) +"
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`Ta(K-2)
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`Ta(K-1)
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`I
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`Fig.6
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`US 7,698,097 B2
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`1
`METHOD FOR CONTROLLING A
`PEDOMETER BASED ON THE USE OF
`INERTIAL SENSORS AND PEDOMETER
`IMPLEMENTING THE METHOD
`
`BACKGROUNDOF THE INVENTION
`
`2
`regularity are satisfied; and preventing updating ofthetotal
`numberofvalid steps if the conditions of regularity are not
`satisfied.
`
`BRIEF DESCRIPTION OF THE SEVERAL
`
`
`VIEWS OF THE DRAWINGS
`
`The present invention relates to controlling a pedometer
`based on the use ofinertial sensors.
`
`weD
`
`DETAIL ED DESCRIPTION OF THE INVENTION
`
`
`
`Forabetter understanding, ofthe invention, an embodiment
`1. Field ofthe Invention
`thereof is now described, purely by way of non-limiting
`D
`example and with referenceto the attached plate of drawings,
`wherein:
`l'IG. 1 showsa simplified and partially sectioned perspec-
`2. Description of the Related Art
`tive view of a portable electronic device incorporating a
`As is known, a pedometeris a device that can be carried by
`pedometer according to the present invention;
`a user and hasthe function of counting the numberof steps
`FIG.2 is a simplified block diagram of the pedometer of
`during various walking or running activities for estimating
`FIG.1;
`accordingly the distance traveled. The indications supplied
`FIG. 3 shows a flowchart corresponding to a control
`are useful for quantifying the motoractivity performed by a
`method according to the present invention executed by the
`personin the course ofa givenperiod, for instance, for clinical
`pedometer of FIGS. 1 and 2;
`i)D
`purposes, for assessing the athletic performance, or even just
`VIG. 4 is a more detailed flowchart correspondingtoafirst
`for simple personal interest.
`step of the method of FIG.3;
`Thereliability of a pedometer obviously depends on the
`FIG. 5 is a graphthat representsfirst quantities used in the
`precision in estimating the step length of the user at the
`method according to the present invention;
`various rates of locomotion, but also on the selectivity in
`FIG. 6 is a graph that represents second quantities used in
`recognizing and ignoring events not correlated to the gait,
`the method according to the present invention;
`which, however, cause perturbations resembling those pro-
`FIG. 7 is a more detailed flowchart corresponding to a
`duced bya step. For example, many pedometersare based on
`second step of the method of FIG. 3; and
`the use ofinertial sensors, which detect accelerations along a
`FIG. 8 is a more detailed flowchart correspondingto a third
`substantially vertical axis, and recognizethat a step has been
`step of the method ofI'IG. 3.
`being madeby a user when the timeplot of the acceleration
`
`
`signal shows given morphological characteristics. Basically,
`a step is recognized when the pedometer detects a positive
`acceleration peak (1.e., a peak directed upwards) having an
`amplitude greater than a first threshold, followed, at a dis-
`tance of some tenths of second, by a negative acceleration
`peak (directed downwards) having an amplitude greater than
`a second threshold. However, there are many randomevents
`that can interfere with correct recognition of the step. Impact
`or other external vibrations and given movementsof the user
`can, in fact, give rise to so-called “false positives”, 1.e., to
`events that are recognized as steps even thoughin actualfact
`they are not, because the morphological characteristics pro-
`duced are compatible. Events of this type are very frequent
`also in periods of rest, when the user, albeit not walking, in
`any case performs movements that can be detected by the
`pedometer. In the majority of cases, also “isolated” steps or
`very brief sequences of steps are far from significant and
`w2
`should preferably be ignored becausethey are, in effect, irrel-
`evant in regard to assessmentof the motor activity for which ~
`the pedometer is being used.
`Of course,in all these situations, the count ofthe steps may
`prove to be completely erroneous.
`
`35
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`&D
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`55
`
`With reference to FIGS. 1 and 2, a pedometer 1 is inte-
`grated within a portable electronic device, such as a cell
`phone 2. The pedometer 1 comprises an inertial sensor 3, a
`control unit 5, equipped with a nonvolatile-memory module
`(not illustrated herein), a display 6, and a communication
`interface 8, all housed on a card 9, which is, in turn, fixed
`within a casing 10 of the cell phone 2. In the embodiment
`described herein, the control unit 5 performs control func-
`tions of the pedometer 1 and, moreover, presides over bi-
`directional communication and over handling of the func-
`tions envisaged for the cell phone 2. Likewise, the display 6,
`; Which is obviously arranged so as to be visible from the
`outside of the casing 10, can be used for displaying both
`informationregarding the pedometer 1 and, more in general,
`information regarding the operation of the cell phone 2.
`Theinertial sensor3 is a linear accelerometer of a MEMS
`(micro-electromechanical systems) type and is mounted on
`thecard 9 so as to havea detection axis Z substantially parallel
`to a longitudinal axis L ofthe casing 10 ofthe cell phone 2. In
`practice, the detection axis Z and the longitudinal axis L are
`substantially horizontal, when the cell phone2 is resting on a
`surface, and substantially vertical or slightly inclined with
`respect to the vertical whenthecell phone 2 is handled. The
`inertial sensor 3 supplies at output an acceleration signal Az,
`which is correlated to the accelerations undergone by the
`inertial sensor3 itself along the detection axis Z.
`The control unit 5 receives and processes the acceleration
`signal A, as explained in detail hereinafter for identifying and
`counting a total numberof valid steps N,-; made by a user
`wearing, or carrying the pedometer1, for example, onhis belt
`or on his shoulder. In addition, the control unit 5 is preferably
`configured for generating, an estimate of the distance traveled
`by the user and other data, such as, for example, estimates of
`the average speed during movement and energy consumption.
`
`BRIEF SUMMARYOF THE INVENTION
`
`One embodimentof the present invention is a method for
`controlling a pedometer and a pedometer which overcomethe
`described abovelimitations.
`
`One embodimentis a methodfor controlling a pedometer.
`The methodincludes: generating a signal correlated to move-
`ments of a user of the pedometer, detecting steps of the user
`based on the signal; checking whether sequences of the
`detected steps satisfy pre-determined conditions of regular-
`ity; updating a total numberofvalid steps if the conditions of
`
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`US 7,698,097 B2
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`4
`3
`after the test on the state flag F.,. of block 120 of FIG.3, the
`The total numberofvalid steps N,-- and the other data possi-
`surveying procedureis executed, block 140). Otherwise (out-
`bly produced are sent to the display 6.
`The communicationinterface 8 inthis case is based onthe
`put NO from block 205), the duration of the time interval T,
`is compared with a second time threshold T,,, shorter than the
`transceiver system (knownand not shown)ofthe cell phone 2
`first time threshold 'l',, and equal, for example, to 3 s (block
`and, preferably, also comprises a port (also known and not
`215). If the second time threshold T,, has been exceeded
`shown) for communication with a computer. The communi-
`(output YES from block 215), the number of valid control
`cation interface 8 can thus be used both for downloading the
`steps N,,- and the numberof invalid steps N,,,,-are set to zero
`data produced by the pedometer 1 (amongst whichatleast the
`(block 220); then a step-recognition test is carried out (block
`total numberofvalid steps N,,,) and for uploading operating
`225). Otherwise (output NO from block 215), the control unit
`parameters tor the pedometer 1 into the control unit 5.
`5 directly executes the step-recognitiontest.
`The control unit 5 is configured for executing a control
`In the step-recognition test of block 225, the control unit 5
`procedure, asillustrated with reference to FIGS. 3-8.
`Upon switching-on of the pedometer 1, aninitialization
`verifies whether the time plot of the acceleration signal A,
`
`step is executed (block 100, FIG. 3), in whichafirst counter (i.e., the sequence of the samples acquired) has pre-deter-
`5
`of the total number ofvalid steps N,,;; a second counter,
`mined characteristics. In particular (IG. 5), a step is recog-
`hereinafter referred to as numberof valid control steps N,-3
`nized if the acceleration signal A, shows a positive peak,
`and a third counter, hereinafter referred to as number of
`higherthan a positive acceleration thresholdAz,followed by
`invalid steps N;,,, are set to zero.
`a negative peak, smaller than a negative acceleration thresh-
`The control unit 5 then executesa first counting procedure
`old Az,, and if the negative peak falls within a time window
`(block 110), based upon the sampling ofthe acceleration
`TW ofpre-determined amplitude and. moreover, located at a
`pre-determined distanceafter the positive peak.
`signal A,, at a pre-determined frequency, for example 25 Hz.
`n this step, the user is considered at rest and the control unit
`If the control unit 5 docs not recognize an event corre-
`5 is considered as waiting to recognize, on the basis of the
`sponding to a step (output NO fromblock 225), a new sample
`acceleration signal Az, sequences of events corresponding to
`of the acceleration signal Az is read (block 200). If, instead,
`§
`a sequence ofsteps that are close to one another, whichsatisfy
`the step-recognition test is passed (output YES from block
`225), the control unit 5 executesafirst validation test, corre-
`pre-determined conditions of regularity described in detail
`hereinafter. When a sequence of steps corresponding to a
`spondingto the regularity of the individual step (block 230).
`Withreference also to FIG.6, the validation occurs whenthe
`regular gait of the user is recognized, the first counting pro-
`cedure is interrupted. Alternatively, the first counting proce-
`duration AT, of a current step K is substantially homoge-
`dure terminates whena timeinterval I’. that has elapsed from
`neous with respect to the duration AT, , of an immediately
`
`he last step recognized is longer thanafirst time threshold preceding step K-1 (the duration of a generic step is deter-
`Ts, for example 10 s. On exit from the first calculation
`mined by the time that has clapsed between an instant of
`recognitionofthe step of whichthe durationis evaluated and
`procedure, the control unit 5 sets a state flag Fto a first value
`C, if a sequenceofsteps that satisfies the conditions of regu-
`an instant of recognition of the step that immediately pre-
`arity has been recognized, and to a second value PI, if the
`cedesit). More precisely, the last step recognizedis validated
`first time threshold T,,, has been exceeded.
`if the instant of recognition of the current step T,(IX) falls
`Atthe end of the first counting procedure, the control unit
`within a validation interval TV, defined with respect to the
`5 checks whether the state flag F,, has beenset at thefirst
`instant of recognition of the immediately preceding step
`value C (block 120),i.e., whether a sequenceofsteps has been
`T,(K-1), in the following way:
`recognized. If so (output YTS from block 120), a second
`TV=[Tp(K-)+ATx1-TA, Tp(K-1+ATx +7B]
`counting procedure is executed (block 130). The user is con-
`sidered to be moving, andafirst counter, hereinafter referred
`where TA and TB are complementary portions of the valida-
`tion interval TV.
`In the embodiment of the invention
`o as total numberof valid steps N,, is incremented when-
`ever an event correspondingto a step is recognized. Further-
`described herein, the complementary portions TA, TB are
`more,the control unit 5 checksthe regularity ofthe sequences
`> defined as follows, for the generic current step K:
`of steps, as explained hereinafter, and, when an interruption in
`TA=APxp/2
`he locomotionis detected, the second counting procedure is
`erminated, and execution of the first counting procedure
`resumes(block 110).
`w2
`If, instead, the state flag F,,. has the second value PD,the <
`pedometer1 is set in a low-consumption wait state (“power
`down”state), and the control unit 5 executes a surveying
`procedure (block 140). The surveying procedure terminates
`when a variation of the d.c. component of the acceleration
`signal A, is detected, i.e., when the cell phone 2 that includes 55
`
`D
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`i)D
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`30
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`5
`
`
` he pedometer 1 is moved. The control unit 5 then returns to
`
`execution ofthe first calculation procedure (block 110).
`The first counting procedure is illustrated in greater detail
`in FIG. 4.
`Initially, the control unit 5 reads a sample ofthe accelera-
`tion signal A,, (block 200) and thenevaluates whetherthe time
`interval T, that has elapsed from the last step recognized is
`higherthanthe first time threshold T.,, i-e., whether the step
`recognitionfails for a period longerthanthefirst time thresh-
`old T,, (black 205). If so (output YES from block 205), the
`state flag F.,.is set at the second value PD (block 210) and the
`first counting procedure is terminated (in this eventuality,
`
`TB-AT4
`
`Consequently, the validation interval is asymmetrical with
`respect to the instant T,(K-1)+AT,.., and has an amplitude
`equal to 3AT,,/2. The validation interval TV could, how-
`ever, be symmetrical and have a different amplitude. In prac-
`tice, it is verified that the last step recognized is compatible
`with the frequency of the last steps made previously.
`If the verification yields a negative result (output NO from
`block 230), the numberofinvalid steps Nj; is incremented
`by one (block 235) before being compared with a first pro-
`grammable threshold number N,,, for example 3 (block 240).
`If the number of invalid steps N,,,- has reached the first
`threshold number N,,, (output YES fromblock 240), both the
`numberofinvalid steps Nyx, and the numberofvalid control
`steps N,,. are set to zero (block 245), and thefirst counting,
`procedure is resumed, with reading of a new sample of the
`5 acceleration signal A, (block 200). If, instead, the number of
`invalid steps N,,,, is smaller thanthe first threshold number
`N,, (output NO from block 240), the numberofvalid control
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`5
`steps N,,. is decremented (block 250). In the embodiment
`described herein, the decrementis equal to two. Ifthe result of
`the decrement operation is negative, the number of valid
`control steps N;,< is set to zero (in practice, the updated value
`of the numberof valid control steps N,< is equal to the
`smaller between zero and the previous value ofthe number of
`valid control steps N,,., decreased by two). Then, the control
`unit § reads a new sample of the acceleration signal A, (block
`200).
`Ifthe first validation test ofblock 230is passed, the number
`ofvalid control steps N,,. is incremented by one (block 255),
`and thenthe control unit 5 executesa first test on regularity of
`he sequenceofsteps recognized (block 260). Thefirst regu-
`arity test is based upon a first condition of regularity and
`envisages comparing the numberofvalid control steps Ny-
`with a second programmable threshold number N,., greater
`hanthefirst threshold number N,, (for example, 8). In prac-
`ice, the first condition of regularity is satisfied whenthere is
`a significant prevalence of steps spaced in a substantially
`unitorm way, at the most interrupted sporadically by a num-
`ber of irregular steps smaller thanthe first threshold number
`N,,. If the numberofvalid control steps N,- is smaller than
`he second threshold number N,, (output NO from block
`260), the first condition of regularity is not satisfied, and the
`first regularity test indicates that there has not yet been iden-
`ified a sequence of steps corresponding to a sufficiently
`regular gait, and hence the control unit 5 acquires once again
`anewsample of the acceleration signal A, (block 200), with-
`out the total numberofvalid steps N,, being incremented.
`Otherwise (output YI'S from block 260), a sequenceofsteps
`is recognized thatsatisfies the first condition ofregularity, and
`the first regularity test is passed. The numberofinvalid steps
`Nand the number ofvalid control steps N,.. are set to zero,
`whereas the total numberof valid steps N,, is updated and
`incrementedby a value equal to the second threshold number
`N,, (block 265). Furthermore, the state flag Fis set at the
`countvalue, and the first counting procedureis terminated.In
`this case, after the test onthe state flag ofblock 120 of FIG.3,
`the second counting procedure is executed (block 130).
`In practice,the first counting procedure enables the pedom-
`eter 1 to remain waiting for a sequence of events correspond-
`ing to a sequenceofsteps that satisfics the first condition of
`regularity. The regularity of the gait is considered sufficient
`when the numberofvalid control steps N;- reaches the sec-
`ond threshold number N,,. The events considered irregular or
`a waiting time that is too long between two successive steps
`cause the decrement (block 250) or the zeroing (blocks 220
`and 245) of the numberofvalid control steps N,,,, so that the
`first counting procedure resumesfrom the start. As long as the
`w2
`pedometer 1 is in the waiting condition, the total number of <
`valid steps N,,. is not incremented because the useris still
`considered as at rest. However, when the first regularity test
`(block 260) is passed,the total numberof valid steps N,, is
`immediately updated soas to take into accountthe valid steps
`(equal to N,.) that make up the sequence considered as being 55
`regular. Isolated events and sequenceof steps that are in any
`case too short are thus advantageously ignored, whereas
`counting of the steps promptly resumes also in the case of
`isolated irregularities (for example, due to a non-homoge-
`neous acceleration or to a loss of balance at the start of
`locomotion).
`The possibility of programming the value of the first
`threshold number N,, and of the second threshold number
`N,, enables modification of the sensitivity of the pedometer
`in recognizing an initial sequence of steps. For example, the
`user can program lowervaluesofthefirst threshold number
`N,, and of the second threshold number N;, (for example 2
`
`5
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`6
`and 4, respectively) when he remains for a long time in a
`closed environment, for example an office or a room, whereit
`would not in any case be possible to maintain a regular gait for
`a long time.In this way, shorter sequences of steps are vali-
`dated and counted.
`Instead, durmg a more constant and
`intense activity, such as running,the gait remains constant for
`a long time, and hencethefirst threshold number N,, and the
`second threshold number N,;, can be programmed with
`higher values (for example, 4 and 12, respectively). Step
`sequencesthat are shorter and not very significant in relation
`to the activity performed can be ignored.
`FIG.7 illustrates in detail the second counting procedure
`(executed in block 130 of FIG.3).
`The control unit 5 initially reads a sample of the accelera-
`tion signal Az (block 300), and then evaluates whether the
`timeinterval T.. that has elapsed from thelast step recognized
`is higher than the first second time threshold T.» (block 305).
`Ifso (outputYES fromblock 205), the numberofinvalid steps
`Nj,and the numberofvalid control steps N,,- are zeroized
`(block 310), and the second counting procedureis terminated.
`Otherwise (output NO from block 305), a step-recognition
`test is carried out (block 315), identical to the step-recogni-
`tion test of block 225 of FIG. 3. Also inthis case, then, step
`recognition is based upon the detection of a positive peak of
`the acceleration signal A, followed by a negative peak that
`falls in the time window TW (see FIG. 5).
`If the control unit 5 docs not recognize an event corre-
`sponding to a step (output NO fromblock 315), a new sample
`of the acceleration signal Az is read (block 300). If, instead,
`the step-recognition test is passed (output YS from block
`315), a second validation test is made, corresponding to the
`regularity of the individual step (block 320). The second
`validationtest is altogether similar to the first validation test
`carried out in block 230 of FIG.3. Also in this case, then. the
`last step recognized is validated ifthe instant of recognition of
`the current step T-(§) falls within the validation interval TV
`defined above. In practice, it is verified that the last step
`recognized is compatible with the frequency of the last steps
`madepreviously.
`Ifthe checkyields a positive result (outputYT'S from block
`320), the control unit 5 updates the total numberofvalid steps
`N,,,and the numberofvalid control steps N,,, incrementing
`them by one (block 325). The numberof valid control steps
`Ny,is then compared with a third programmable threshold
`5 number N,, (block 330), which,in the embodiment described
`herein, is equal to the second threshold number N,5. If the
`numberof valid control steps N,< is smaller than the second
`threshold number N, (output NO fromblock 330), the con-
`trol unit 5 once again directly acquires a new sample of the
`acceleration signal A, (block 300), whereas otherwise (out-
`put YES from block 330), the numberofinvalid steps N,,),
`and the number of valid control steps Nj,are set to zero
`(block 335) prior to acquisition of a new sample A,.
`If, instead, the second validation test of block 320 is nega-
`tive, the numberofinvalid steps N,,;-is incremented by one
`(block 340) before being compared with a fourth program-
`mable threshold number N,, (block 345), which,
`in the
`present embodiment, is equal to the first threshold number
`N,,. If the numberofinvalid steps Nj, is smaller than the
`fourth threshold number N,,, (output NO fromblock 345),the
`number of valid control steps N,,. is decremented (block
`350), here by two. Also in this case, if the result of the
`decrement operationis negative, the number ofvalid control
`steps N,< is set to zero (the updated value of the number of
`valid control steps N,< is equal to the smaller between zero
`and the previous value of the numberof valid control steps
`Ny, decreased by two). Then, the control unit 5 reads a new
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`7
`sample ofthe acceleration signal A, (block 300). If the num-
`ber of invalid steps N,,,,- has reached the fourth threshold
`number N,, (output YES from block 345), the number of
`invalid steps N,,,-and the numberofvalid control steps Ny-
`are set to zero (block 355), and the second counting procedure
`is terminated.
`
`In practice, the second counting procedure is based on a
`second condition of regularity, which is satisfied as long as
`sporadic irregular steps occur within sequences of steps
`spaced in a substantially homogeneous way. Moreprecisely,
`the second condition of regularity is satisfied as long as the
`numberof invalid steps N,,,,-is smaller than the fourth thresh-
`old number N;,,. Consequently, the second counting proce-
`dure continues to update and increment the total number of
`valid steps N,-- as long as the gait of the user is kept regular.
`Possible isolated irregularities are ignored and do not inter-
`rupt or suspend updating of the count, which is,
`instead,
`interrupted when prolonged pauses occur or in the presence
`of significant discontinuities in locomotion. However,if the
`gait becomesregular again, even with a different rhythm,also
`the count promptly resumes, because the first counting pro-
`cedure is once again executed. This prevents a significant
`numberof steps from being neglected.
`The surveying procedure executed in block 140 of FIG. 3
`will now be described in greater detail, with reference to FIG.
`8.
`
`Whenthe surveying procedure is started, a current mcan
`value A,,, of the acceleration signal A; is stored in the non-
`volatile-memory module(notillustrated) ofthe control unit 5
`(block 400). The current mean value A,,, represents an esti-
`mate of the DC component of the acceleration signal A,,
`which, when the cell phone 2 containing the pedometer 1 is
`stationary, is determined substantially by the contribution of
`the acceleration of gravity along the detection axis Z. In
`practice, then, the current mean value A,,, provides anesti-
`mate of the position of the cell phone 2 and of the pedometer
`1.
`
`
`
`After storage ofthe current mean value Az,,, the pedometer
`1 is set in a low-consumption operating condition (power-
`down condition), in which at least the inertial sensor 3 is
`inactive (block 410).
`Awaiting cycle is then carried out (block 420), for example
`of the duration of 10 s, after whichall the functions of the
`pedometer1 are re-activated (“power on’, block 430).
`The control unit 5 acquires from the inertial sensor 3 a
`numberof samplesofthe acceleration signal A, sufficient for
`estimating an updated mean value A,,/ (block 440), whichis
`hen compared with the current mean value Az,, previously
`stored (block 450).
`If the updated mean value A,,,/ departs from the current
`mean value A,,, (output NO from block 450), the surveying
`procedure is interrupted, and the first counting procedure
`indicated in block 110 of FIG.3 is executed. If, instead, the
`updated mean value A,,/ is substantially unvaried with
`respect to the current mean value A,,, (output YES from
`block 450). the surveying procedure proceedsand the pedom-
`eter | is set again in the low-consumption operating condition
`(block 410).
`Clearly, the use ofthe surveying procedure enables a dras-
`ic reduction in the power consumption when the pedometer
`1 is not used and, hence increases the autonomythereof.If, as
`in the embodiment described, the pedometer1 is integrated in
`a portable device with whichit shares the use ofresources, for
`example the control unit 5, the surveying procedure entails
`further advantages. In fact, the de-activation of the functions
`linked to the pedometer1 frees the shared resourcesfor use by
`
`0
`
`5
`
`i)D
`
`25
`
`weD
`
`35
`
`50
`
`55
`
`Qa
`
`8
`the active functions, which can thus access the resources
`themselves in a moreefficient way.
`Finally, it is evident that modifications and variations can
`be made to the device described herein, without thereby
`departing from the scopeof the present invention, as defined
`in the annexed claims.
`In particular, the control procedure described can be used
`to advantage in a stand-alone pedometer or in any case one
`integrated in a further portable device, but with stand-alone
`and non-shared resources.
`Furthermore, the conditions of regularity used to enable or
`prevent counting ofthe steps recognized canbe different from
`the ones described. For example, a sequence of steps can be
`considered regular when possible steps recognized and not
`validated are separated byat least one pre-determined number
`of consecutive validated steps. Again, a sequence ofa pre-
`determined numberof validated or non-validated steps (se-
`quence offixed length) can be considered regular when the
`validated steps are at least a given percentage ofthe steps of
`the sequence.
`Finally, the inertial sensor can be of the type with two or
`three axes of detection. In this case, step recognition can
`advantageously be performed by selecting the acceleration
`signal corresponding to the detection axis nearest to the ver-
`tical. The nearer the detection axis used is to the vertical, in
`fact, the greater the amplitude of the signal useful for step
`recognition. The detection axis is selected on the basis of the
`value of the DC component of the respective acceleration
`signal, which is correlated to the contribution ofthe accelera-
`tion ofgravity. ‘lhe detection axis nearest to the vertical1s the
`axis along which the contribution of the acceleration of grav-
`ity is greater. The pedometer can then be used independently
`of howit is oriented.
`The invention claimed is:
`1.A methodfor controlling a pedometer, the method com-
`prising:
`generating a signal correlated to movements ofa user ofthe
`pedometer;
`detecting steps of the user based on said signal:
`checking whether sequencesofthe detected steps indicate
`whether the sequencesof the detected steps correspond
`to a regular gait of the user;
`updating, a total number of valid steps if said sequences
`correspond to the regular gait of the user;
`preventing updating ofsaid total numberofvalid steps if
`said sequences do not correspondto the regular gait of
`the user; and
`partially deactivating, the pedometerif said detecting steps
`of the user based on said signal fails for a period longer
`thana time threshold.
`2, The method accordingto claim 1, wherein said checking
`comprises:
`in a first operating condition, checking whether a first
`condition of regularity is satisfied; and
`in a second operating condition, checking whethera sec-
`ond condition of regularity is satisfied.
`3. The method according to claim 2, wherein, during said
`checking whethersaid first condition ofregularityis satisfied,
`the updating ofsaid total numberofvalid steps is prevented.
`4. The method according to claim 2, wherein, during, said
`checking whether said second condition of regularityis sat-
`isfied, the updating of said total numberof valid steps is
`allowed.
`5. A methodfor controlling a pedometer, the method com-
`prising:
`generating a signal correlated to movements ofa user ofthe
`pedometer;
`
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`US 7,698,097 B2
`
`9
`detecting steps of the user based on said signal;
`checking whether sequences ofthe detected steps indicate
`whether the sequencesofthe detected steps correspond
`to a regular gait of the user;
`updating a total number of valid steps if said sequences
`correspond to the regular gait of the user; and
`preventing updating of said total numberofvalid steps if
`said sequences do not correspondto the regular gait of
`the user,
`wherein checking whether sequencesof the detected steps
`indicate whether the sequences of the detected steps
`correspond to a regular gait of the user includes:
`executinga first validation test ofa current detected step;
`incrementing a numberof valid control steps if based on
`said first validation test said current detected step is
`validated; and
`incrementing a numberofinvalid steps and decrementing
`said numberof valid control steps if based on saidfirst
`validation test said current detected step is not validated.
`6. The method according to claim 5, wherein said execut-
`ing said first validation test of said current detected step
`comprises evaluating whether a duration of said current
`detected step is homogeneouswith respect to a duration of an
`immediately preceding detected step.
`7. The method according to claim 6, wherein said first
`validation test yields a positive result when an instant of
`recognition of the current detected step T,(K) falls within a
`validation interval, defined with respect to an instant of rec-
`ognition of the immediately preceding detected step T,(K-
`1), in the following way:
`TV=[T(K-1)+AT_|-TA, Ty(K-1)4AT_+TB]
`
`5
`
`5
`
`20
`
`25
`
`30
`
`where AT,_, is said duration of the immediately preceding
`detected step, and TA and TB are complementary portions of
`said validation interval.
`8. The method according to claim 5, further comprising
`checking whethera first condition of regularity is satisfied,
`wherein said checking whether said first condition of regu-
`larity is satisfied comprises comparing said numberofinvalid
`steps with a first threshold number and comparing said num-
`ber of valid control steps with a second threshold number.
`9. The method according to claim 8, wherein said first
`condition of regularity is satisfied if said number of valid
`control steps is equal to said second threshold number.
`10. The method according to claim 8, further comprising
`checking whether a second cond