Patent Application
20050049517
This invention relates generally to electromyogram sensing.
Muscle tissue contracts and relaxes as a function, at least in part, of the presence and absence of triggering biologically-based electrical signals. Sensors can be employed to detect such signals. The resultant waveforms are typically referred to as electromyograms.
Such sensors must ordinarily be located in direct contact with a skin surface proximal to the muscle tissue of interest. Corresponding electrodes are utilized to source a small potential across a portion of the muscle tissue and another electrode serves to detect the electrical response of the muscle tissue to this potential.
The resultant electromyogram information can be helpful to diagnose various medical conditions having characteristic symptomatic muscle tissue conditions. Such information could also potentially be used with respect to various physical activities (such as sports training or physical rehabilitation) that have a corresponding characteristic desired or expected muscle tissue reaction. To date, however, employment of such information remains relatively restricted. This likely results, at least in part, due to relatively significant barriers to obtaining and then rendering useful such information.
For example, obtaining electromyograms typically entails deployment and subsequent equipment operation by a skilled and trained operator. Appropriate placement of the electrodes with respect to one another, for example, typically requires a priori experience and training regarding such systems. Skill and expertise regarding affixing the electrodes in a desired position using, for example, tape or other adhesives can also present an obstacle to usage by ordinary people. Furthermore, electromyogram information itself yields relatively non-intuitive results to all but trained and experienced interpreters.
As a result, obtainment and use of electromyogram information remains largely confined to relatively limited clinic applications.
The above needs are at least partially met through provision of the electromyogram method and apparatus described in the following detailed description, particularly when studied in conjunction with the drawings, wherein:
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.
Generally speaking, pursuant to these various embodiments, a conformable housing supports an electromyogram sensor, an electromyogram signal processor, and a display. In a preferred embodiment, the conformable housing is of sufficient size to permit substantially conformal disposition about a human body part (such as, but not limited to, a portion of an arm or of a leg). In a preferred approach, the electromyogram sensor joins the conformable housing in such as fashion as to permit the sensor to detect muscle activity when the conformable housing is substantially conformally disposed about a human body part. Pursuant to a variety of embodiments, the display provides information (in textual, graphical, or other suitable form) that corresponds to a muscle condition parameter (such as, but not limited to, muscular fatigue). Such information can be, if desired, a composite indicia that corresponds to a condition of, for example, a plurality of muscles or a particular muscle as viewed, for example, over time.
In some embodiments, a memory also couples to the electromyogram signal processor. This memory can provide information that the electromyogram signal processor utilizes when processing the electromyogram sensor data. As one example, the memory can include comparative (and/or calibration) information regarding strength (for example, for a given specific individual, as corresponds in general to a particular target demographic audience, or otherwise). As another example, the memory can include information regarding past performances (such as, for example, a past number or rate of muscle flextures or muscle relaxation events for a given individual).
Pursuant to one embodiment, a plurality of distally positioned electromyogram sensor mechanisms can provide information to a given electromyogram signal processor to permit a unified or discrete presentation of corresponding muscle status information. When using a plurality of sensors, the resultant information can be provided to the electromyogram signal processor via a wireline and/or a wireless channel. If desired, the electromyogram signal processor itself can also be provided with a transmitter capability. So configured, the electromyogram signal processor can, for example, provide processed muscle activity or status information to a remote display and/or to another processing unit as desired.
In some applications it may be appropriate to provide a calibration capability. So configured, the resultant apparatus can be calibrated with respect to a given individual (or, for example, a class of individuals) to facilitate a more accurate interpretation of the resultant electromyogram waveforms. Such calibration can make use of locally stored calibration and/or remotely stored calibration information as may be appropriate to the given application. Such calibration can also be based upon specific actions taken by a user in response, for example, to specific calibration instructions as provided to the user.
So configured, a relatively untrained individual can make beneficial and accurate use of electromyogram waveform information. For example, these embodiments tend to permit proper disposition and use of the electromyogram sensors without requiring a copious amount of training regarding proper placement of the electrodes (particularly with respect to one another). These embodiments also tend to facilitate relatively rapid placement and removal of the electromyogram sensors as, essentially, a beneficial side effect of simply donning the conformable housing. These embodiments also support the provision of relatively simple and intuitive information that is nevertheless of value and benefit to an untrained and unskilled observer. This, in turn, permits use of such embodiments in a wide variety of non-clinical settings and for a wide variety of non-traditional purposes. For example, such electromyogram information can be used to supplement or even define a wide variety of physical training activities, including training for competitive sports as well as physical therapies. Furthermore, such benefits are attainable at a relatively modest cost.
Referring now to the drawings, and in particular to
It is possible that the conformable housing 11 could be offered in various lengths and widths to facilitate accommodation of a wider variety of body part sizes and shapes. For example, a longer conformable housing might be preferred for use with the upper torso while a shorter conformable housing may be better suited to use with a smaller body part (such as a bicep muscle area of the arm). Depending upon the choice of materials, the conformable housing 11 can be comprised of a single layer (having cavities or other support mechanisms incorporated therein to permit support of the other elements described below) or can by comprised of multiple layers as desired. When using multiple layers, one may also elect to utilize layers of differing materials to better accommodate some particular design requirement (regarding, for example, weight, water resistance, strength, washability, breathability, printability, and so forth).
The conformable housing 11 serves as a housing and/or as a support substrate for a number of other preferred and/or optional components. In a preferred embodiment, these include an electromyogram signal processor 13, an electromyogram sensor (comprised in this depiction of three electrodes 14 as comports with ordinary prior art practice), and a display 15. The electromyogram signal processor 13 can be architecturally comprised of a single integrated device or a plurality of devices as desired and/or appropriate to a given application. In addition, the electromyogram signal processor 13 can comprise a fixed-purpose platform or can be at least partially programmable. Such architectural variations and options are generally well understood in the art. In general, the electromyogram signal processor 13 will preferably be relatively small (such as a single integrated circuit) and consume only a small amount of power. This signal processor 13 serves, in general, to receive the electromyogram signals from the electromyogram sensor and to process those signals to at least provide corresponding information via the display 15. (Additional description regarding operation of the electromyogram signal processor 13 appears below where appropriate.)
The display 15 can be any of a wide variety of display technologies including, but not limited to, a liquid crystal display. In a preferred embodiment the display 15 comprises a multi-color display and may optionally comprise an alphanumeric display to permit provision of textual content. In general, this display 15 serves to at least provide information that corresponds to a muscle condition parameter. For example, the display 15 can provide indicia that corresponds to muscular fatigue. As one exemplary illustration of this capability, and referring momentarily to
In this embodiment, the conformable housing 11 also supports a portable power source 16. The portable power source 16 can comprise, for example, one or more batteries. Such batteries can be disposed on an outer surface of the conformable housing 11 or can be disposed within the housing 11. The portable power source 16 can be disposed within a pocket or other opening in the conformable housing 11 to permit access thereto. Such access will facilitate servicing and changing the portable power source 16. In the alternative, if desired, the portable power supply 16 can be more permanently secured within the conformable housing 11. Such disposition may be appropriate when using, for example, a rechargeable portable power source. Charging electrodes can be externally provided when using a rechargeable portable power source. In the alternative, the rechargeable portable power source can comprise a non-contact rechargeable portable power source as is known in the art. (Such non-contact rechargeable portable power sources use, for example, inductive coupling to facilitate recharging the power source.)
In an optional embodiment, the conformable housing 11 can also support a user input interface 17. This user input interface 17 may comprise, for example, a switch such as a push button switch. Other input mechanisms, including multi-switch mechanisms, are of course possible to suit the needs of a given application. Such a user input interface 17 can be used to accommodate a variety of purposes. For example, a user can use such an interface 17 to place the electromyogram signal processor into an active mode of operation. Other uses are also possible.
The electromyogram device 10 can include other elements and features as well. At least some other possibilities are noted below where appropriate.
So configured, the electromyogram device 10 can be readily disposed about a muscle of interest. Notwithstanding placement by a person with little or no electromyogram sensor training, the described form factor will nevertheless tend to encourage proper placement of the various electrodes 14. These embodiments also permit relatively rapid placement of the device 10 and removal as well. Neither the individual components themselves nor the manner of their combination requires extraordinary skill, equipment, or expense to successfully employ.
Referring now to
If desired, the electromyogram signal processor 13 can also couple to one or more external memories 31. Such memory 31 can store electromyogram information as detected and/or processed by the electromyogram signal processor 13. Such memory can also hold other kinds of information, including but not limited to:
In one embodiment, the electromyogram device 10 can also include an audible alarm 32 that operably couples to, for example, the electromyogram signal processor 13. If desired or necessary, a power amplifier (not shown) can also be included to effect provision of an audible signal of desired amplitude. Such an audible alarm 32 can serve, for example, to signal attainment of a given state of being with respect to one or more monitored muscle condition parameters. To illustrate, an audible alarm can be sounded when a predetermined level of muscle fatigue occurs or when at least a given level of muscle fatigue persists for more than a predetermined period of time.
In another embodiment, the electromyogram device 10 can also include a wireless receiver and/or transmitter 33. Such a capability can serve a variety of purposes. For example, so configured, the electromyogram signal processor 13 can receive electromyogram signals from additional remote electromyogram sensors. This, in turn, will permit the electromyogram signal processor 13 to process (and compare and contrast as appropriate) signals that represent a current condition of more than a single muscle. A transmission capability will permit the electromyogram signal processor 13 to transmit, for example, electromyogram information (including, for example, display information) to, for example, a remote or supplemental display.
Referring now to
Pursuant to one approach, the rectified electromyogram signal is normalized 45 and then processed with respect to its power spectrum 46. The power for each frequency component represented by a corresponding Fast Fourier Transform can be obtained by squaring the magnitude of that frequency component; the “power spectrum” then relates to a plot of that power in each of the frequency components. The mean power frequency 47 is then ascertained to thereby provide information that corresponds to muscle fatigue and endurance. In a preferred approach, mean power frequency comprises a weighted average frequency in which each frequency component f is weighted by its power P (for example, P1 is the power of f1). More particularly, the mean power frequency can be obtained by summing the frequency times power of the components and then dividing by the sum of the powers. That is:
Mean power frequency=(f1*P1+f2*P2+. . . +fn*Pn)/(P1+P2+. . . +Pn)
Pursuant to another embodiment, the rectified electromyogram signal is integrated 43 to thereby provide information that corresponds to strength and power. Pursuant to yet another embodiment, the rectified electromyogram signal is subjected to an average amplitude 44 process to yield information that corresponds to muscle fatigue. As to the latter, the electromyogram signal amplitude increases as the simultaneous muscle action potentials sum. The average amplitude then comprises a calculation result for the sum of the electromyogram signal values over a designated interval divided by the time interval. Such average amplitude is often expressed as a percentage of the value with respect to so-called maximum voluntary contraction.
As muscle fatigue has been shown to be accompanied by increases in electromyogram signal amplitude and decreases in mean power frequency, such values can be helpful in interpreting the data obtained through these embodiments. For example, in order to calibrate a biceps fatigue level, a subject can perform repetitive elbow flexion-extension movements while holding a five kg weight in hand until volitional exhaustion occurs. Biceps brachii electromyogram signals can be recorded continuously during such a test and the corresponding electromyogram signal power spectrum and average amplitude then calculated accordingly. The mean power frequency and/or average amplitude can then be used to characterize the temporal history of changes and to express or characterize the electromyogram signal features at different fatigue levels.
The above approaches to developing information regarding fatigue, endurance, strength, and power are each understood in the art. Therefore, additional detail will not be provided here for the sake of brevity and the preservation of focus.
Any of the above described indicia can then be utilized by the electromyogram signal processor to develop a corresponding information display.
Pursuant to one approach, the electromyogram signal processor can display a numerical or alphanumeric value or representation that correlates to the absolute or relative value of the electromyogram information. Pursuant to another approach, the electromyogram signal processor can compare the electromyogram information against other information or thresholds to facilitate the display of a corresponding representation. For example, the electromyogram signal processor 13 can provide one informational presentation when the present monitored muscle condition parameter is less than a predetermined limit and another information presentation when the present monitored muscle condition parameter exceeds this predetermined limit.
As a more specific example, the electromyogram signal processor 13 can utilize the average amplitude 44 approach to extract information from the electromyogram signals regarding muscular fatigue. This extracted information can then be compared against a predetermined threshold that represents (for a given individual, a class of individuals, or such other point of comparison as may be useful and pertinent in a given setting), for example, a target level of activity or a safety limit beyond which the monitored individual should not exceed.
It would also be possible to use more than one of the above described methods (or, indeed, to use other methods now known or hereafter developed) in combination with one another to yield a more complete, accurate, and/or fusion-based informational result. For example, both mean power frequency 47 and average amplitude 44 can be utilized to develop a redundant and/or averaged view of muscular fatigue. As another example, both mean power frequency 47 and integration 43 can be utilized to matrix and/or fuse, as desired, metrics regarding both endurance and power to provide a composite vector regarding present muscular conditions. And, as before, the electromyogram signal processor 13 can then depict in any appropriate fashion the resultant information in a scalar and/or un-scaled relativistic fashion as desired.
It would be possible to effect the above processing in a manner that treats all monitored individuals as being essentially equal. For many purposes, however, it may be more appropriate to adjust the processing to reflect special conditions, needs, purposes, or aspirations of the particular individual being monitored. One way to accommodate such flexibility is to provide calibration 48 that effects appropriate corresponding changes in how the electromyogram signal processor 13 conducts the above described processing. Additional detail will be provided below regarding such calibration.
First, however, it may be helpful to first provide additional explanation with respect to various embodiments and configurations of usage that may be accommodated via some or all of these embodiments. With reference to
As noted earlier, the device 10 can include a wireless receiver. Therefore, if desired, a second electromyogram device 51 can be disposed elsewhere on the individual 50 (for example, as illustrated, on the opposing arm). This second electromyogram device 51, when equipped with a transmitter as described above, can transmit its electromyogram information (either the raw data itself or the processed or partially processed data as appropriate to a given implementation) to the first electromyogram device 10. The first electromyogram device 10 can then utilize this additional information in a variety of ways. As one example, the additional information can be discretely displayed on a second display 34 as described above. As another example, the additional information can be fused with the locally developed information (for example, by averaging the additional information in a weighted or unweighted fashion with the locally developed information) to permit provision of a single displayed metric that represents a combined view of both muscle tissues. As yet another example, a single display 15 can be alternatively toggled between informational displays for both information sources. Other possibilities also exist.
Along these same lines, a secondary (or other supplemental) electromyogram device 52 that lacks a local display can also be used as desired. Such a device 52 may be particularly appropriate for use with muscle tissues where direct convenient observation of the display may not be readily possible. In such a case, and by providing the secondary electromyogram device 52 with a transmitter, the electromyogram information can be provided wirelessly to the first electromyogram device 10 where the remotely developed information can be displayed and/or otherwise processed as desired.
It would also be possible to provide a wearable mechanism 53 that comprises a remote display 54 and an appropriate receiver. So configured, the latter can be worn in a location where the individual 50 has convenient viewing access to the remote display 54 such that electromyogram information as developed by the electromyogram device 10 (either alone or as based upon inputs from other electromyogram devices) is displayed in a convenient location as selected by the individual 50. In a somewhat similar fashion the electromyogram device 10 can also transmit information to a remotely positioned receiver 55. For example, the electromyogram device 10 can transmit electromyogram information to be displayed on a display 56 upon reception by the receiver 55. Such a remote display mechanism can serve a variety of purposes. For example, the individual 50 could place the device in a convenient location distal to their body to possibly even more easily facilitate viewing the display. As another example, another individual, such as a monitoring trainer or physical therapist, could utilize such a remote display to remain conveniently apprised of the individual's muscular status and condition.
These or other suitable platforms can be used to effect a process such as that set forth in
As noted above, the processing activity can serve to ascertain and quantify a variety of indicia regarding the monitored muscle tissue including, for example, muscle fatigue. It is also possible to process information concerning a plurality of muscles in order to determine, for example, a composite indicia that corresponds to the condition of such muscles. Such processing can comprise an effective measurement of the parameter or parameters of interest and/or the comparison of such parameters against one or more criteria. Such criteria can include, for example, one or more threshold values that correspond, for example, to a user performance parameter of interest. Such thresholds can be relatively static or dynamically determined and can be relatively broad-based or specific and personal to a given individual (for example, a given threshold value can be determined as a function, at least in part, of one or more past performances by the user).
As also noted above, such processing activity may also be based upon or otherwise utilize calibration information and/or a calibration process. There are various ways to effect or otherwise support such calibration activity. For example, and referring now to
If the user does not respond accordingly 73 (within, for example, a predetermined period of time T 74) to the calibration instruction, a predetermined action 75 can be taken. For example, the calibration instruction can again be provided to the user. As another example, the calibration instruction can be repeated in conjunction with provision of an audible alarm. These examples are illustrative of the concept and many other alternative actions are of course possible.
When the user does respond according to the calibration instruction, the calibration process 70 can then utilize the resultant electromyogram information when providing 77 the calibration criterion to be used during the above described processes. For example, when the calibration instruction requires the individual to effect flexures until noticeable fatigue becomes apparent, then the number of flextures as occurred during the calibration window (as can be determined automatically by the embodiments set forth above), plus or minus some constant or other weighting factor as may be appropriate to a given application, can be used when developing a threshold value to use when subsequently evaluating muscle activity for this individual (or other individuals of like circumstance when so desired).
In addition to such specifically developed user performance information, or in lieu thereof, the calibration process 70 can optionally comprise accessing 75 previously stored calibration information. Such accessing can comprise accessing locally stored calibration information and/or remotely stored calibration information (the latter via an appropriate communication link as comports with the resources and capabilities of a given setting). Such calibration information can comprise a wide variety of content. For example, information regarding past performance milestones of relevance for this particular individual can be accessed. As another example, similar information as corresponds to a group of people who are sufficiently similar to the present user to warrant such usage can be accessed. As yet another example, information regarding performance thresholds of interest for model performance can be accessed. This latter example would permit a given individual to compare their own capacity and performance against, for example, the performance of a role model, a composite standard, or a target level of performance, to name a few.
Pursuant to the various embodiments set forth above, muscles are readily monitored by an easily donned and readily understood electromyogram device. The resultant information can be used in various ways. For example, an individual may be able to effect a training regimin while assuming a reduced risk of injury through over exertion. As another example, a trainer may be able to better supervise the performance of a group of individuals. As yet another example, an individual may be able to more readily compare and contrast their present performance against their own past performance, target levels of performance, the performance of a role model, or some other relevant standard.
Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept. For example, and referring now to
