TW202406501A - Pseudomonopolar electrode configurations for emg sensing - Google Patents

Abstract

Disclosed herein are methods, systems, apparatuses, and media for sensing neuromuscular signals. In one example, a device for sensing neuromuscular signals comprises a wearable structure. The device includes a plurality of signal electrodes aligned along an interior portion of the wearable structure, each signal electrode configured to detect neuromuscular signals. The device further includes a plurality of amplifiers corresponding to the plurality of signal electrodes, wherein an amplifier has: a first input operatively coupled to a corresponding signal electrode; a second input; and an output corresponding to a neuromuscular signal channel. The device further includes circuitry configured to generate a common mode reference signal directly or indirectly based on signals from one or more electrodes, wherein the second input of each amplifier of the plurality of amplifiers is configured to receive the common mode reference signal or a signal based on the common mode reference signal.

Description

Virtual monopolar electrode configuration for electromyography sensing

This application relates to virtual monopolar electrode configurations for electromyography sensing.

Surface electromyography (sEMG) electrodes are used to measure action potential signals as they propagate down the muscle fibers. These action potential signals can be correlated with motor cortical activity. As wearable devices (e.g., wrist-worn devices such as smart watches or fitness trackers) become more common, incorporating sEMG sensing into wearable devices can provide useful information, such as detecting hand, Wrist, finger and/or arm movement. However, using sEMG electrodes in consumer devices is difficult, for example because consumer devices require dry electrodes to be placed on the skin surface. Conventional techniques using dry surface electrodes can result in less reliable detection of sEMG activity, which can produce poor quality data and/or inaccurate data.

In some aspects, a device for sensing neuromuscular signals includes a wearable structure configured to be worn by a user. The device may include a plurality of signal electrodes configured to be aligned along an interior portion of the wearable structure proximate a user's skin surface, each signal electrode of the plurality of signal electrodes being configured to detect a neuromuscular signal. The device may include a plurality of amplifiers corresponding to a plurality of signal electrodes, wherein an amplifier of the plurality of amplifiers has: a first input operatively coupled to a corresponding signal electrode of the plurality of signal electrodes; a second input; and Output, which corresponds to the neuromuscular signaling pathway. The apparatus may include circuitry configured to generate a common-mode reference signal directly or indirectly based on signals from one or more electrodes, wherein the second input of each amplifier of the plurality of amplifiers is configured to receive the common-mode reference signal. A reference signal or a signal based on a common-mode reference signal in which one or more electrodes are configured to measure activity from the same muscle group as a plurality of signal electrodes.

In some examples, the one or more electrodes include a single reference electrode, and wherein the single reference electrode is disposed along an interior portion of the wearable structure.

In some examples, one or more electrodes include a plurality of reference electrodes that are different from a plurality of signal electrodes. In some examples, each of the plurality of reference electrodes is operatively coupled to a buffer, the output of the buffer corresponding to the common-mode reference signal.

In some examples, the one or more electrodes that generate the common-mode reference signal include at least a subset of the plurality of signal electrodes. In some examples, each signal electrode in a subset of the plurality of signal electrodes is operatively coupled to a buffer, the output of the buffer corresponding to the common-mode reference signal. In some examples, outputs of a plurality of amplifiers corresponding to a subset of a plurality of signal electrodes are operatively coupled via corresponding plurality of resistors to generate a common-mode reference signal. In some examples, the device further includes: one or more analog-to-digital converters (ADCs) that convert the outputs of the plurality of amplifiers into digital outputs; a digital circuit system configured to Determine the common-mode digital signal based on the digital output; and a digital-to-analog converter (DAC) that generates a common-mode reference signal based on the common-mode digital signal.

In some examples, the wearable structure includes a wrist-worn structure.

In some examples, a plurality of signal electrodes are positioned circumferentially around an interior portion of the wearable structure.

In some examples, the same muscle group includes wrist extensors and/or wrist flexors.

In some examples, a plurality of signal electrodes aligned along an interior portion of the wearable structure are configured to contact the user's skin surface.

In some examples, a device for sensing neuromuscular signals includes a wearable structure configured to be worn by a user. The device may include a plurality of signal electrodes configured to be aligned along an interior portion of the wearable structure proximate a user's skin surface, each signal electrode of the plurality of signal electrodes being configured to detect a neuromuscular signal. The device may include a plurality of amplifiers corresponding to a plurality of signal electrodes, wherein an amplifier of the plurality of amplifiers has: a first input operatively coupled to a corresponding signal electrode of the plurality of signal electrodes; an inverting input; and Output, which corresponds to the neuromuscular signaling pathway. The apparatus may include circuitry configured to operatively couple a plurality of outputs of a plurality of amplifiers to generate a common-mode reference signal, wherein the common-mode reference signal is provided to an inverting input of each of the plurality of amplifiers.

In some examples, a given output of a given amplifier of the plurality of amplifiers is operatively coupled to the inverting input via one or more resistors. In some examples, the device further includes a capacitor in series with a first of the one or more resistors, wherein the capacitor and the first resistor form a high-pass filter configured to attenuate DC offset from the corresponding signal electrode. device. In some examples, the device further includes a resistor in parallel with the capacitor, wherein the resistor in parallel with the capacitor acts as a current leakage path. In some examples, the device further includes a capacitor in parallel with a second of the one or more resistors, wherein the capacitor forms part of a low-pass filter configured to perform anti-frequency overlap of the neuromuscular signal path.

In some examples, the wearable structure includes a wrist-worn structure.

In some examples, a plurality of signal electrodes are positioned circumferentially around an interior portion of the wearable structure.

In some examples, neuromuscular signals are associated with wrist extensor muscles and/or wrist flexor muscles.

Surface electromyography (sEMG) is used to measure action potential signals as they propagate down the muscle fibers. These action potential signals correlate with motor cortical activity. Therefore, sEMG can be used to detect muscle activity and infer motor cortex activity based on the detected muscle activity. This may be useful, for example, in inferring an individual's expected movement patterns. sEMG may be particularly useful when implemented on wearable devices, such as wrist-worn devices (eg, smart watches, fitness trackers, etc.) or arm-worn devices. For example, sEMG activity can be used to detect finger, hand, wrist and/or arm muscle activity, which can be used to infer the wearer's intended movements in pointing, gestures, pinching and grasping, writing, etc. Continuing this example, the inferred expected movements can be used to interact with user interfaces, virtual reality (VR), and/or without touching the touch screen or utilizing a stylus, mouse, or keyboard. Interaction with augmented reality (AR) environments, and for many other possible use cases.

Due to wearer comfort and safety issues, consumer devices utilizing sEMG typically use dry surface electrodes rather than wet or penetrating electrodes. Although comfortable to the wearer, dry surface electrodes have disadvantages that affect the quality of the recorded sEMG data. For example, dry surface electrodes can have higher impedance, which can reduce signal-to-noise ratio. As another example, conventional techniques typically utilize a unipolar electrode configuration in which each signal electrode is referenced by a non-electroactive reference electrode, or differential sensing in which the difference between two signal electrodes is measured. Each has its shortcomings. For example, a unipolar sensing signal incorporates a common mode signal common to all electrodes. In the case of dry surface electrodes, the common-mode signal can be dominated by power line interference or other artifacts (which can be much larger than the signal of interest). In the case of differential sensing, the common mode signal is subtracted - this allows to obtain (i.e., by subtracting the power line interface) the signal of interest, in which there is some of the interest that is discarded by differential sensing signal. For example, for a wrist-worn device, common-mode signals may indicate muscle activity in muscle fibers that are not strictly longitudinal (eg, from elbow to wrist). Additionally, differential sensing requires additional electrodes to obtain a given number of signal channels.

Described herein are electrode configurations and techniques for generating a common reference signal for use by multiple signal electrodes to generate corresponding sEMG signal channels. The use of a common reference signal is often referred to herein as a "virtual unipolar" configuration because, like a unipolar configuration, the signal electrodes are referenced to a common signal (e.g., a common reference signal), which allows for portions of the common-mode signal Incorporated into each of the sEMG signal pathways. The signal from the signal electrode can then be amplified relative to the common reference signal. However, unlike a true unipolar configuration, the virtual unipolar configuration described in this article effectively discards artifacts in the common-mode signal, such as power line interference. Therefore, the virtual monopole configuration described herein can provide good artifact suppression while incorporating useful and/or interesting portions of the common-mode signal, such as muscle activity in non-longitudinal fibers. This enables more accurate inference of expected movement patterns.

Describe various techniques for achieving virtual unipolar configurations. In one example, a common reference electrode is used to generate a common reference signal, which is used for comparison by multiple signal electrodes, as shown and described below in conjunction with FIG. 1 . In another example, signals from multiple reference electrodes are used to generate a common reference signal that is used for comparison by multiple signal electrodes, as shown and described below in conjunction with FIG. 2 . In yet another example, the signal electrode output itself is used to generate a common reference signal, as shown and described below in conjunction with Figure 3A. In yet another example, the outputs of operational amplifiers each receiving the output of a signal electrode are used to generate a common reference signal, as shown and described below in connection with FIGS. 4 and 5 . In yet another example, the outputs of the signal electrodes are used to algorithmically generate a common reference signal, as shown and described below in connection with FIG. 6 .

In some embodiments, signal electrodes and/or reference electrodes may be incorporated into a wearable device, such as a wrist-worn device. For example, in some implementations, electrodes may be disposed in and/or on a portion of a wearable device such that the electrodes are each configured to contact a portion of the wearer's skin. In some implementations, electrodes may be disposed circumferentially around a strap of the wrist-worn device. Additionally or alternatively, in some implementations, two or more electrodes (eg, a signal electrode and a reference electrode, two signal electrodes, etc.) may be longitudinally disposed within a portion of the band of the wrist-worn device such that two or more Multiple electrodes are placed along the longitudinal fibers of the muscle (for example, as the fibers extend from the elbow to the wrist). In some embodiments, all electrodes may have the same size and/or shape. Rather, in some embodiments, different electrodes may have different sizes and/or shapes. For example, in some implementations, the reference electrode may have a different size and/or shape than the signal electrode.

It should be noted that in instances where one or more reference electrodes are used to generate a common reference signal, the one or more reference electrodes may measure activity from the same muscle group as the signal electrodes. In contrast, conventional techniques for measuring sEMG activity using reference electrodes place the electrodes on electrically neutral tissue relative to the signal of interest. By way of example, in the case where the muscle activity of interest corresponds to arm, hand, wrist and/or finger muscles, conventional techniques can place signal electrodes close to the arm, hand, wrist and/or finger muscles, and can One or more reference electrodes are placed on unrelated body parts such as chest, temples, legs or the like. In the techniques described herein, in instances where one or more reference electrodes are used to generate a common reference signal, the reference electrode can be positioned proximate the signal electrode such that both the reference electrode and the signal electrode measure signals from the same muscle group. Activity. Such muscle groups may include arm, wrist, hand and/or finger extensors, flexors, abductors, adductors, or the like. In some embodiments, the reference electrode and the signal electrode can be positioned on and/or along the wrist wear device such that the reference electrode and signal electrode respectively measure signals from agonist-antagonist muscle pairs, such as wrist flexor muscles. and activities of wrist extensor muscles or the like. To measure activity from the same muscle group, one or more reference electrodes (if used) and signal electrodes can both be placed in and/or along the same wrist-worn device (e.g., worn along the wrist One or more strap portions of the device are mounted, mounted on the back portion of the capsule of the wrist-worn device, or the like). In some implementations, the reference electrode can be near the signal electrode, for example, within a range of about 3 millimeters to 10 centimeters.

In some implementations, a single reference electrode is used to generate a common reference signal that serves as a comparison signal for multiple signal electrodes. In other words, a single reference electrode can be used for comparison of multiple signal electrodes by providing a common reference signal utilized by each of the multiple signal electrodes. For example, each signal electrode is operably coupled to a first input of an instrumentation amplifier, wherein the output of each instrumentation amplifier corresponds to the sEMG channel. Continuing this example, a common reference signal generated using a single reference electrode can be provided to a second input (eg, the inverting input) of the instrumentation amplifier, such that the common reference signal is effectively subtracted from the signal from each signal electrode, and such that for Each signal channel amplifies the signal of the signal electrode relative to the common reference signal. A common reference signal can be generated from a single reference electrode. A single reference electrode can be placed on the electrically active tissue of interest, such as a portion of the skin over the muscle fibers of interest, rather than on an electrically neutral surface like a ground electrode. As described above, the signal reference electrode measures activity from the same muscle group as the signal electrode. Thus, a common reference signal generated by a single reference electrode may include signals of interest, such as signals from muscle fibers underlying the reference electrode. In some implementations, the output of the reference electrode may be buffered (eg, using an operational amplifier). Buffering the output of the reference electrode allows impedance matching between the reference electrode and the second input of the instrumentation amplifier. In other words, buffering the output of the reference electrode allows the signal at the second input of each instrument amplifier to be of similar magnitude.

It should be noted that in some implementations, multiple reference electrodes may be used such that a first reference electrode provides a common reference signal for a first set of signal electrodes and a second reference electrode provides a common reference for a second set of signal electrodes. signal, etc.

Additionally, it should be noted that the techniques, devices, and/or systems used herein describe electrodes (signal electrodes and/or reference electrode). As used herein, "proximate the skin surface" may include an electrode in contact with the wearer's skin surface, wherein at least a portion of the electrode touches the wearer's skin surface. Alternatively, "proximate the skin surface" may include electrodes within a relatively small distance of the skin surface (eg, within 1 micron, 10 microns, 100 microns, 1 millimeter, 5 millimeters, or another suitable smaller distance).

Figure 1 shows a schematic diagram of an example electrode configuration using a single reference electrode to generate a common reference signal for multiple sEMG channels. As illustrated, signal electrodes 104, 106, 108, and 110 may each be used to generate corresponding sEMG channels (depicted as "Channel 1,""Channel2,""Channel3," and "Channel 4," respectively in Figure 1) . It should be noted that the number of signal electrodes shown in FIG. 1 is only exemplary, and in some specific examples, other numbers of signal electrodes (eg, one, two, five, ten, twenty) may be used. wait). The output of each signal electrode can be provided to the first input of the corresponding instrument amplifier. For example, signal electrode 104 is operatively coupled to a first input of instrumentation amplifier 112 , signal electrode 106 is operatively coupled to a first input of instrumentation amplifier 114 , and signal electrode 108 is operatively coupled to instrumentation amplifier 116 The first input of the signal electrode 110 is operatively coupled to the first input of the instrument amplifier 118 . Each signal electrode is resting on a portion of the wearer's body 102 , which may be the wearer's wrist for a wrist-worn device, the wearer's arm for an armband device, or a portion of the wearer's leg for a device that contacts the wearer's leg. legs etc.

The inverting input of each instrument amplifier is operatively coupled to reference electrode 120 . As illustrated in FIG. 1 , reference electrode 120 is also in contact with a portion of body 102 . In other words, the reference electrode 120 is not placed on electrically neutral or electrically non-electroactive tissue. Rather, reference electrode 120 is positioned such that reference electrode 120 measures signals from the same muscle group as those measured by signal electrodes 104 to 110 . In the example shown in FIG. 1 , the output of reference electrode 120 is buffered by operational amplifier 122 . However, it should be noted that in some embodiments, operational amplifier 122 may be omitted, and the output of reference electrode 120 may be provided directly to each of the inverting inputs of instrumentation amplifiers 112 - 118 . Because each sEMG channel is a differential signal subtracted from a common reference signal generated using reference electrode 120, artifacts such as power line interference can be removed from each sEMG channel. Furthermore, because each sEMG channel is generated using the same common reference signal, common-mode signals of interest (such as from axially aligned muscle fibers) can generally be incorporated into each sEMG channel.

Additionally, Figure 1 shows a ground electrode 124, which can be used to generate a system ground.

In some implementations, multiple reference electrodes may be used to generate a common reference signal used to generate multiple sEMG channels. For example, in some embodiments, a common reference signal may effectively correspond to an average of signals from multiple reference electrodes. In one example, the output of each reference electrode may be buffered, for example, to provide impedance matching on the inverting inputs of multiple instrumentation amplifiers provided with a common reference signal. Continuing this example, the outputs of each buffer can then be combined via a set of resistors, with a common reference signal corresponding to the signal of the set of resistors. In some implementations, the output of the resistor set may be buffered via an optional operational amplifier to provide further impedance matching. Similar to the electrode configuration shown and described above in connection with Figure 1, a common reference signal can then be provided to the inverting input of multiple instrumentation amplifiers, where the output of each instrumentation amplifier is the sEMG channel.

Figure 2 shows a schematic diagram of an example electrode configuration using multiple reference electrodes to generate a common reference signal. Similar to what was shown and described above in connection with Figure 1, the outputs of signal electrodes 104-110 are operatively coupled to first inputs of corresponding sets of instrumentation amplifiers 112-118, where the outputs of each instrumentation amplifier correspond to the sEMG channel . Similar to what was shown and described above in connection with Figure 1, the inverting input of each instrumentation amplifier receives a common reference signal. However, unlike what is shown in Figure 1, in the electrode configuration shown in Figure 2, multiple reference electrodes (eg, reference electrodes 202, 204, 206, and 208) are used to generate a common reference signal. As illustrated in Figure 2, a corresponding operational amplifier is used to buffer the output of each reference electrode. For example, operational amplifier 210 is used to buffer the output of reference electrode 202, operational amplifier 212 is used to buffer the output of reference electrode 204, operational amplifier 214 is used to buffer the output of reference electrode 206, and operational amplifier 216 is used to buffer the output of reference electrode 208. The buffered outputs of the plurality of reference electrodes are then combined via a corresponding set of resistors (eg, resistors 218-224, as shown in Figure 2). In some implementations, the combined signals correspond to a common reference signal. In some embodiments, optional operational amplifier 226 is optionally used to buffer the combined signal, where the buffered combined signal corresponds to a common reference signal.

It should be noted that although FIG. 2 shows the same number of reference electrodes as signal electrodes, this is only an example. In some implementations, a different number of reference electrodes may be used relative to the number of signal electrodes. For example, in some implementations, two reference electrodes may be used to generate a common reference signal for use by eight signal electrodes. As another example, in some implementations, four reference electrodes may be used to generate a common reference signal for use by ten signal electrodes. In some specific examples, multiple common reference signals may be generated, each generated by a different reference electrode group. In these specific examples, different groups of signal electrodes may utilize common reference signals. By way of example, signal electrodes 1 to 4 may utilize a common reference signal generated by reference electrodes 1 and 2 , and signal electrodes 5 to 8 may utilize a common reference signal generated by reference electrodes 3 and 4 . In some embodiments, signal electrode groups utilizing different common reference signals may partially overlap.

In some implementations, a common reference signal may be generated using signal electrodes rather than using one or more physical reference electrodes. For example, in some implementations, a common reference signal may correspond to a combination or average of the outputs of multiple signal electrodes. As a more specific example, in some embodiments, the common reference signal may be a combination of buffered outputs of multiple signal electrodes. In some embodiments, each signal electrode is operatively coupled to a first input of a corresponding instrument amplifier, and an inverting input of each instrument amplifier can receive a common reference signal that is a signal of at least a subset of the plurality of signal electrodes. Combined output (or combined buffered output). In some embodiments, the combined output (or the combined buffered output) of at least a subset of the plurality of signal electrodes may then be buffered (eg, to provide impedance matching, as described above) to produce a common reference signal. By generating a common reference signal without utilizing any physical reference electrodes, cost and/or space savings can be achieved on wearable devices. For example, a smaller total number of electrodes may be placed in and/or on a wearable device. Additionally or alternatively, by not utilizing physical reference electrodes, additional signal electrodes can be utilized, allowing for more robust and/or detailed sEMG acquisition.

3A shows a schematic diagram of an example electrode configuration using signal electrodes to generate a common reference signal according to some specific examples. As illustrated in Figure 3A, the outputs of signal electrodes 104-110 are buffered by corresponding operational amplifiers. For example, the output of signal electrode 104 is buffered by operational amplifier 302 , the output of signal electrode 106 is buffered by operational amplifier 304 , the output of signal electrode 108 is buffered by operational amplifier 306 , and the output of signal electrode 110 is buffered by operational amplifier 308 . The buffered output of each signal electrode is provided as a first input to a corresponding instrument amplifier (eg, instrument amplifiers 112-118). The output of each instrument amplifier corresponds to the sEMG channel, as shown and described above in conjunction with Figures 1 and 2.

However, unlike what is shown in Figures 1 and 2, in the electrode configuration depicted in Figure 3A, each signal is combined via a corresponding set of resistors (eg, resistors 310, 312, 314, and 316) The buffered outputs of the electrodes (depicted as "Single 1", "Single 2", "Single 3" and "Single 4" respectively) produce a common reference signal. The common reference signal is then provided to each inverting input of each instrument amplifier. In some implementations, the combined signal output may correspond to a common reference signal. In the example shown in Figure 3A, the combined signal output is buffered by optional operational amplifier 318, and the buffered combined signal output corresponds to a common reference signal provided to each inverting input.

It should be noted that although FIG. 3A depicts generating a common reference signal by combining (eg, effectively averaging) the outputs of all signal electrodes, in some embodiments, a common reference may be generated by combining a subset of the outputs of the signal electrodes. signal. For example, in the case where there are four signal electrodes, the outputs of two of the four signal electrodes or three of the four signal electrodes may be used to generate a common reference signal. Additionally, in some embodiments, multiple common reference signals may be generated, each combining the outputs of at least a subset of the signal electrodes. For example, a first subset of signal electrodes (eg, signal electrodes 1-4) may be used to generate a first common reference signal, and a second subset of signal electrodes (eg, signal electrodes 5-8) may be used to generate the first common reference signal. A second common reference signal is generated. In some embodiments, each subset of signal electrodes may include a different number of signal electrodes or the same number of signal electrodes.

Figure 3B depicts another example implementation using an electrode configuration based on a common reference signal from one or more signal electrodes. Similar to what was shown and described above in connection with Figure 3A, a common reference signal is provided to each inverting input of each instrumentation amplifier based on the buffered output of each signal electrode. Figure 3B illustrates resistors 350, 352, 354, and 356 placed in series with the buffered output of each signal electrode. It should be noted that in a printed circuit board (PCB) implementation, any of the resistors 350 - 356 may or may not be filled to control the number of signal electrodes used to generate the common reference signal. For example, in the case where only resistor 350 is filled, only the buffered output of electrode 1 is utilized to generate the common reference signal. Implementations that fill only one signal resistor in 350 - 356 and therefore utilize only the output of a single electrode to generate a common reference signal are sometimes referred to herein as "single point reference" or SPR implementations. As another example, populate the PCB with one of as many of resistors 350 - 356 (eg, two of four resistors, three of four resistors, or four of four resistors) For example, a common reference signal may be generated using corresponding buffered outputs corresponding to multiple signal electrodes. Implementations that utilize multiple of resistors 350 - 356 and thus multiple signal electrodes to generate a common reference signal are sometimes referred to herein as input-generated common reference signals.

In some implementations, a common reference signal may be generated using signal electrodes without using any physical reference electrodes, where the common reference signal is generated based on the output of an amplifier that receives signals from the signal electrodes and generates outputs corresponding to the sEMG channels. For example, in some embodiments, the output of each signal electrode is operatively coupled to a first input of each of a set of operational amplifiers, wherein the output of the operational amplifier corresponds to the sEMG channel. The inverting input of each operational amplifier may receive a common reference signal, with the common reference signal itself being generated based on the output of the operational amplifier. For example, a common reference signal may represent a combination of the outputs of multiple operational amplifiers. In other words, in some specific examples, a common reference signal may be generated based on a combination (eg, effectively, an average) of multiple sEMG channels (eg, all sEMG channels or a subset of sEMG channels). By using the output of an op amp to generate a common reference signal, less physical hardware may be required. In particular, fewer operational amplifiers may be needed because there is no need to buffer the signal electrode output, as in the specific example shown and described above in connection with FIG. 3A. Using fewer op amps allows for improved signal-to-noise ratio (SNR). Improved SNR may allow improved overall performance, for example, by enabling improved performance in spike classification of individual action potential spikes, which in turn may allow improved performance associated with fine motor actions such as typing or handwriting. Additionally, no physical reference electrode is required, which saves space and cost and/or allows the use of additional signal electrodes.

4A is a schematic diagram illustrating an example electrode configuration using an sEMG output signal to generate a common reference signal according to some specific examples. As illustrated, signal electrodes 104, 106, 108, and 110 are operatively coupled to first inputs of corresponding operational amplifiers 402, 404, 406, and 408. Each operational amplifier generates a signal corresponding to the sEMG channel as an output. The output of the operational amplifier is used to generate a common reference signal. For example, as illustrated in Figure 4A, the _Rg resistor 410, _Rf resistor 412, _Rg resistor 414, _Rf resistor 416, _Rg resistor 418, _Rf resistor 420, R _g resistor 422, and R _f resistor 424) to combine the outputs of the operational amplifiers to produce a common reference signal. As illustrated, a common reference signal is provided at the inverting input of each op amp.

Figure 4B illustrates a schematic diagram of an example implementation of the electrode configuration shown and described above in connection with Figure 4A. As illustrated, capacitor 452 may be coupled in series with R _g resistor 410 . Capacitor 452 in combination with Rg resistor 410 may act as a high-pass filter to attenuate the DC offset from the sEMG signal obtained from electrode 104 . The value of capacitor 452 and the value of R _g resistor 410 can be used to set the cutoff frequency of the high pass filter. In some implementations, capacitor 452 may have a value in the range of approximately 2 μF to 10 μF. In some implementations, _Rg resistor 410 may have a value in the range of approximately 1 kilohm to 5 kilohm. In some implementations, resistor 454 may be placed in parallel with capacitor 452. Resistor 454 can act as a DC path for leakage current, which can be used to stabilize the common average reference. In other words, because multiple electrodes are tied together to create a common average reference (eg, as shown in Figure 4A), the common average reference can be considered to be weakly driven. Therefore, by acting as a DC path for leakage current, resistor 454 stabilizes a common average reference allowing the reference signal to be more robust. It should be noted that although capacitor 452 may attenuate the DC offset, the DC offset may not completely cancel. In other words, the DC information may be passed at low gain (eg, 0 dB), which may allow the DC information to be utilized, such as for lead detection of individual electrodes, or the like.

As illustrated, in some embodiments, there may be a capacitor 456 in parallel with the R _f resistor 412 . Capacitor 456 and resistor 460 may together act as a low-pass filter that performs anti-aliasing before providing the signal to the analog-to-digital converter (ADC). In some embodiments, capacitor 456 may have a value in the range of approximately 100 pF to 300 pF. In some embodiments, R _f resistor 412 may have a value in the range of approximately 200 kilohms to 400 kohms. In some implementations, resistor 454 may have a value in the range of approximately 1.5 kilohms to 5 kohms. As illustrated, in some implementations, there may be a capacitor 462 connecting the output to ground. Resistor 360 and capacitor 462 may be used to stabilize the input to the ADC. This prevents oscillation and mitigates charge kickback from the ADC. In some implementations, capacitor 462 may have a value in the range of approximately 20 nF to 50 nF.

FIG. 5 is a schematic diagram illustrating how the circuit shown in FIG. 4A effectively averages the outputs of operational amplifiers 402, 404, 406, and 408 to generate a common reference signal. The outputs of operational amplifiers 402, 404, 406, and 408 are depicted as voltage sources 502, 504, 506, and 508, respectively. Each voltage source corresponds to the sEMG channel, as described above in connection with Figure 4A. Resistors 410 to 424 are illustrated in FIG. 5 . Using Millman's Theorem, the common reference signal at R _g 410, R _g 414, R _g 418 and R _g 422 can be determined as follows:

The above equation can be simplified so that the common reference signal can be determined by:

In other words, as illustrated by the schematic diagram shown in Figure 5, the circuit depicted in Figure 4A generates a common reference signal that is effectively the average (eg, mean) of the sEMG channels. It should be noted that although FIG. 4A illustrates an electrode configuration that generates a common reference signal by averaging all sEMG channels, in some specific examples, a common reference signal may be generated by averaging a subset of sEMG channels. For example, in some implementations, the outputs of a subset of sEMG channels may be combined (eg, averaged) using the techniques shown and described above in connection with FIG. 5 . In some such embodiments, the inverting input of the operational amplifier may receive the common reference signal, regardless of whether the output of the operational amplifier is used to generate the common reference signal. In some implementations, multiple common reference signals may be generated, each based on a combination (eg, average) of multiple sEMG channels.

In some implementations, the common reference signal may be generated digitally. For example, in some implementations, one or more analog-to-digital converters (ADCs) may be used to convert signals from a set of signal electrodes into digital signals. The digital signal can then be used to determine the common reference signal. For example, digital circuitry may be used to determine the average value (eg, mean, median, etc.) of a digital signal to produce a digital representation of a common reference signal. A digital to analog converter (DAC) can then be used to convert the digital representation of the common reference signal into an analog common reference signal. An analog common reference signal can then be provided at the inverting input of multiple instrument amplifiers, each of which produces an output corresponding to the sEMG signal. Each instrument amplifier can obtain a signal from the signal electrode at a first input. By way of example, referring to Figure 3A, signals from signal electrodes may be provided to digital circuitry (e.g., one or more ADCs, digital circuitry that generates a digital representation of a common reference signal, and/or configured to generate a common reference analog representation of the signal), rather than producing a common reference signal by using a set of resistors and an optional buffer to combine the signals from the signal electrodes.

Figure 6 is a flowchart of an example process 600 for generating a common reference signal using digital circuitry, according to some embodiments. In some embodiments, blocks of program 600 may be executed by one or more processors that may be onboard or on a wearable device with signal electrodes disposed therein. In some embodiments, the blocks of process 600 may be executed in an order other than that shown in FIG. 6 . In some embodiments, two or more blocks of program 600 may execute substantially in parallel. In some embodiments, one or more blocks of process 600 may be omitted.

Process 600 may begin at 602 by receiving voltage measurements from a set of signal electrodes. For example, voltage measurements may be received by one or more ADCs operatively coupled to signal electrodes in a set of signal electrodes. An ADC produces a digital representation of the output of a signal electrode.

At 604, process 600 may generate a common reference signal based on the received voltage measurement. For example, in some embodiments, process 600 may determine an average value of the received voltage measurements, where the common reference signal corresponds to the determined average value. The average may be the mean, median, or the like. The common reference signal may be generated using digital circuitry, which may include algorithms executed by one or more processors. In some implementations, the common reference signal may be a digitized version of the common reference signal. A DAC can then be used to convert the digitized version of the common reference signal into an analog representation.

At 606, process 600 may provide a common reference signal to a set of amplifiers each corresponding to a signal electrode in the set of signal electrodes, where each amplifier produces an output corresponding to the sEMG channel. For example, a common reference signal may be provided to the inverting input of each amplifier, which receives a signal from a corresponding signal electrode at the other input. The common reference signal provided to each amplifier may be an analog version of the common reference signal generated at block 604. In some embodiments, digital circuitry that generates the common reference signal is operatively coupled to the inverting input of each amplifier to provide the common reference signal to each inverting input.

As described above, signal electrodes and reference electrodes (if used) may be disposed in, on, and/or along portions of the wearable device. Figures 7A-7D provide example configurations of signal electrodes and reference electrodes (if used) for an example wrist-worn device. It should be noted that the examples shown in Figures 7A-7D may be used in conjunction with any suitable configuration shown and described above in connection with Figures 1-6. For example, FIG. 7A depicting a single reference electrode may be used to implement a configuration utilizing a single reference electrode shown and described above in conjunction with FIG. 1 . Alternatively, the configuration depicted in Figure 1 can be implemented using a single reference electrode patch as shown and described below in connection with Figure 7D. As another example, FIG. 7B depicting a plurality of reference electrodes may be used to implement the configuration shown and described above in connection with FIG. 2 . Alternatively, in some implementations, the reference patch depicted in Figure 7D can be replicated to form multiple reference electrode patches, which can then be used in the configuration shown and described above in connection with Figure 2. As yet another example, Figure 7C, which does not depict a reference electrode, can be used to implement the configurations depicted in Figures 3, 4, and/or 6, where a common reference signal is generated without a physical reference.

Turning to FIG. 7A , an example wrist-worn device utilizing a single reference electrode is depicted in accordance with some specific examples. The wrist wear device includes a case 702 and a strap portion 704 . It should be noted with respect to Figures 7A-7D that in some implementations, the wrist wear device may include two strap portions (only one of which is depicted in each of Figures 7A-7D). In such embodiments, each strip portion may include a signal electrode and/or a reference electrode (if used). A plurality of electrodes are positioned along strip portion 704. For example, band portion 704 includes reference electrode 706 and signal electrodes 708, 710, 712, 714, and 716. The spacing between electrodes (eg, edge-to-edge spacing) may range from about 3 mm to 20 mm. It should be noted that although all electrodes depicted in Figure 7A are illustrated as having the same size and shape, this is for illustration only. In some specific examples, different electrodes can be of different sizes and shapes (eg, circular, rectangular, etc.). Additionally, it should be noted that although all electrodes are depicted as longitudinally aligned along band portion 704, this is illustrative only. In some implementations, two or more electrodes may be aligned along the width of strip portion 704. The single reference electrode configuration depicted in Figure 7A can be used to implement the generation of a common reference signal using a single physical reference electrode, as shown and described above in connection with Figure 7A. Alternatively, in the case where the second strip portion (not shown in Figure 7A) includes one or more reference electrodes, reference electrode 706, along with any reference electrodes disposed along the second strip portion, may be used to use multiple reference electrodes. The generation of the common reference signal is implemented as shown and described above in conjunction with FIG. 2 .

Turning to FIG. 7B , an example wrist-worn device with multiple reference electrodes is shown according to some specific examples. As illustrated, band portion 704 includes reference electrodes 720 and 726 and signal electrodes 722, 724, 728, and 730. It should be noted that the spacing between reference electrode 720 and reference electrode 726 (eg, with two signal electrodes therebetween) is only illustrative, and in some embodiments, the reference electrode may be connected in any suitable manner (eg, by any suitable A number of intervening signal electrodes, spaced apart on opposing strip portions or the like). Furthermore, it should be noted that although FIG. 7B depicts the reference electrode as aligned with the signal electrode along the length of strip portion 704, this is illustrative only. In some implementations, reference electrodes may be positioned laterally along the strip portion such that the reference electrodes are aligned with specific signal electrodes along the width of the strip. The multiple reference electrodes depicted in FIG. 7B can be used to generate a common reference signal using multiple reference electrodes, as shown and described above in connection with FIG. 2 .

Turning to FIG. 7C , an example wrist-worn device that does not include a physical reference electrode is shown in accordance with some embodiments of the disclosed subject matter. As illustrated, signal electrodes 740 - 754 are positioned aligned along strip portion 704 . Signal electrodes 740-754, or a subset of signal electrodes 740-754, may be used to generate a common reference signal, for example, using the techniques shown and described above in connection with Figures 3-6.

Turning to Figure 7D, an example wrist-worn device utilizing a reference electrode patch is shown according to some specific examples. As illustrated, signal electrodes 750, 752, 754, 756, 758, and 760 are positioned aligned along strip portion 704. Strip portion 704 also includes reference electrode patches 762 , which may be strips along strip portion 704 . In some implementations, signals acquired using reference electrode patch 762 may be used to generate a common reference signal for generating signal channels corresponding to signal electrodes 750 - 760 , as shown and described above in connection with FIG. 1 . It should be noted that in some implementations, the wrist-worn device may include multiple reference electrode patches. In some such embodiments, multiple reference electrode patches may be used in combination to generate a common reference signal, as shown and described above in connection with FIG. 2 .

It should be noted that although the reference electrodes depicted in Figures 7A, 7B, and 7D are illustrated as having the same structure as the signal electrodes (e.g., in the case of Figures 7A and 7B) or strips (e.g., in the case of Figure 7D) The size and shape of the electrodes, in some implementations, may utilize other reference electrode configurations. For example, in some embodiments, the reference electrode may be a concentric ring surrounding the signal electrode.

Additionally, it should be noted that although the signal electrodes and reference electrodes depicted in FIGS. 7A-7D are shown aligned along the strap of the wrist-worn device, in some implementations, one or more signal electrodes and/or one or more A reference electrode may be positioned along the back cover of the bag configured to contact the wearer's wrist.

8 is a simplified block diagram of an example of a computing system 800 for implementing some of the examples described herein. For example, in some embodiments, a computing system may be used to implement a user device (e.g., a mobile phone, a tablet, a wrist-worn device, etc.) that implements the blocks of process 500 shown and described above in connection with FIG. 5 . In the illustrated example, computing system 800 may include one or more processors 810 and memory 820. Processor 810 may be configured to execute instructions for performing operations at several components, and may be, for example, a general purpose processor or a microprocessor suitable for implementation within a portable electronic device. Processor 810 may be communicatively coupled with a plurality of components within computing system 800. To achieve this communication coupling, processor 810 may communicate across bus 840 with other illustrated components. Bus 840 may be any subsystem suitable for moving data within computing system 800 . Bus 840 may include a plurality of computer buses and additional circuitry to move data.

Memory 820 may be coupled to processor 810. In some embodiments, memory 820 may provide both short-term storage and long-term storage, and may be divided into units. Memory 820 may be volatile, such as static random access memory (SRAM) and/or dynamic random access memory (DRAM), and/or non-volatile, such as read-only memory. (read-only memory; ROM), flash memory and the like. Additionally, memory 820 may include a removable storage device, such as a secure digital (SD) card. Memory 820 may provide storage of computer-readable instructions, data structures, program modules, and other data for computing system 800 . In some embodiments, memory 820 may be distributed among different hardware modules. Instruction sets and/or program codes may be stored in memory 820 . The instructions may be in the form of executable code executable by the computing system 800, and/or may be in the form of source code and/or installable code that is executed by the computing system 800. 800 may be in the form of executable code after being compiled and/or installed on the computing system (e.g., using any of a variety of commonly used compilers, installers, compression/decompression utilities, etc.).

In some embodiments, memory 820 may store a plurality of application modules 822 to 824, which may include any number of applications. Examples of applications may include gaming applications, conferencing applications, video playback applications, or other suitable applications. Apps can include depth-sensing capabilities or eye-tracking capabilities. Application modules 822 - 824 may include specific instructions to be executed by processor 810 . In some embodiments, certain applications or portions of application modules 822 - 824 may be executed by other hardware modules 880 . In some embodiments, memory 820 may additionally include secure memory, which may include additional security controls to prevent copying or other unauthorized access to secure information.

In some embodiments, memory 820 may include operating system 825 loaded therein. Operating system 825 may be operable to initiate execution of instructions provided by application modules 822 - 824 and/or manage other hardware modules 880 , and with a wireless communications subsystem that may include one or more wireless transceivers. 830 interface. Operating system 825 may be adapted to perform other operations across components of computing system 800, including threading, resource management, data storage control, and other similar functionality.

Wireless communications subsystem 830 may include, for example, infrared communications devices, wireless communications devices and/or chipsets (such as Bluetooth® devices, IEEE 802.11 devices, Wi-Fi devices, WiMax devices, cellular communications infrastructure, etc.) and/or Similar to communication interface. Computing system 800 may include one or more antennas 834 for wireless communications, as part of wireless communications subsystem 830 or as a separate component coupled to any portion of the system. Depending on the desired functionality, wireless communications subsystem 830 may include individual transceivers to communicate with base transceiver stations and other wireless devices and access points, which may include communications with, for example, a wireless wide-area network (WWAN). , wireless local area network (WLAN) or wireless personal area network (wireless personal area network; WPAN) different data networks and/or network types for communication. A WWAN may be a WiMax (IEEE 802.18) network, for example. A WLAN may be, for example, an IEEE 802.11x network. A WPAN can be, for example, a Bluetooth network, IEEE 802.8x, or some other type of network. The techniques described herein may also be used with any combination of WWAN, WLAN, and/or WPAN. Wireless communications subsystem 830 may permit the exchange of data with networks, other computer systems, and/or any other devices described herein. Wireless communications subsystem 830 may include components for transmitting or receiving data such as identifiers of HMD devices, location data, geographic maps, heat maps, photos, or videos using antennas 834 and wireless links 832 . Wireless communications subsystem 830, processor 810, and memory 820 may together include at least a portion of one or more of the means for performing some of the functions disclosed herein.

Specific examples of computing system 800 may also include one or more sensors 890 . Sensors 890 may include, for example, image sensors, accelerometers, pressure sensors, temperature sensors, proximity sensors, magnetometers, gyroscopes, inertial sensors (e.g., a combination accelerometer and gyroscope). module), an ambient light sensor, any other similar module operable to provide sensing output and/or receive sensing input, such as a depth sensor or a position sensor. For example, in some embodiments, the sensor 890 may include one or more inertial measurement units (IMU) and/or one or more position sensors. The IMU may generate calibration data indicative of the estimated position of the device based on measurement signals received from one or more of the position sensors. The position sensor may generate one or more measurement signals in response to movement of the device. Examples of position sensors may include, but are not limited to, one or more accelerometers, one or more gyroscopes, one or more magnetometers, another suitable type of sensor that detects motion, errors for IMUs A type of calibrated sensor, or a combination thereof. The position sensor can be located outside the IMU, inside the IMU, or some combination thereof. At least some sensors may use structured light patterns for sensing.

Computing system 800 may include display module 860. The display module 860 may be a near-eye display and may graphically present information (such as images, videos, and various instructions) from the computing system 800 to the user. This information may originate from one or more application modules 822 - 824 , the virtual reality engine 826 , one or more other hardware modules 880 , combinations thereof, or be used to parse graphical content for the user (e.g., by Any other suitable component of the operating system 825). The display module 860 can use liquid crystal display (LCD) technology, light-emitting diode (LED) technology (including, for example, OLED, ILED, μLED, AMOLED, TOLED, etc.), or light-emitting polymer display (light emitting polymer display; LPD) technology, or some other display technology.

Computing system 800 may include user input/output module 870. User input/output module 870 may allow a user to send action requests to computing system 800 . An action request may be a request to perform a specific action. For example, an action request may be to start or end an application or to perform a specific action within the application. User input/output module 870 may include one or more input devices. Example input devices may include touch screens, trackpads, microphones, buttons, dials, switches, keyboards, mice, game controllers, or devices for receiving action requests and communicating the received action requests to computing system 800 Any other suitable device. In some examples, the user input/output module 870 can provide tactile feedback to the user according to instructions received from the computing system 800 . For example, tactile feedback can be provided when an action request is received or performed.

Computing system 800 may include a camera 850 that may be used to take photos or videos. Camera 850 can be configured to take photos or videos of the user. The camera 850 can also be used to capture photos or videos of the environment, such as for VR, AR or MR applications. The camera 850 may include, for example, a complementary metal-oxide-semiconductor (CMOS) image sensor having millions or tens of millions of pixels. In some implementations, camera 850 may include two or more cameras that may be used to capture 3D images.

In some embodiments, computing system 800 may include a plurality of other hardware modules 880 . Each of the other hardware modules 880 may be a physical module within the computing system 800 . Although each of the other hardware modules 880 may be permanently configured as an architecture, some of the other hardware modules 880 may be temporarily configured to perform specific functions or be temporarily activated. Examples of other hardware modules 880 may include, for example, audio output and/or input modules (eg, microphones or speakers), near field communication (NFC) modules, rechargeable batteries, battery management systems, wired /Wireless battery charging system, etc. In some embodiments, one or more functions of other hardware modules 880 may be implemented in software.

In some embodiments, the memory 820 of the computing system 800 may also store the virtual reality engine 826. The virtual reality engine 826 can execute applications within the computing system Y100 and receive position information, acceleration information, velocity information, predicted future positions, or some combination thereof from various sensors. In some embodiments, information received by the virtual reality engine 826 may be used to generate signals (eg, display commands) for the display module 860 . For example, if the received information indicates that the user has looked to the left, the virtual reality engine 826 can generate content that reflects the user's movement in the virtual environment. Additionally, the virtual reality engine 826 may perform actions within the application in response to action requests received from the user input/output module 870 and provide feedback to the user. The feedback provided can be visual, auditory or tactile feedback. In some implementations, processor 810 may include one or more GPUs executable virtual reality engine 826 .

In various implementations, the hardware and modules described above may be implemented on a single device or on multiple devices that may communicate with each other using wired or wireless connections. For example, in some implementations, some components or modules, such as a GPU, virtual reality engine 826, and applications (eg, tracking applications) may be implemented on two or more paired or connected devices.

In alternative configurations, different and/or additional components may be included in computing system 800 . Similarly, the functionality of one or more of the components may be distributed among the components in a manner different from that described above. For example, in some embodiments, computing system 800 may be modified to include other system environments such as AR system environments and/or MR environments.

Specific examples disclosed herein may be used to implement components of an artificial reality system or may be implemented in conjunction with an artificial reality system. Artificial reality takes the form of a reality that has been adjusted in some way before being presented to the user, which may include, for example, virtual reality, augmented reality, mixed reality, hybrid reality, or some combination thereof and/ or derivatives. Artificial reality content may include fully generated content or generated content combined with captured (eg, real-world) content. Artificial reality content may include video, audio, haptic feedback, or some combination thereof, and any of these may be presented in a single channel or in multiple channels (such as stereoscopic video that produces a three-dimensional effect on the viewer). In addition, in some specific examples, artificial reality may also be used with applications such as creating content in the artificial reality and/or otherwise being used in the artificial reality (e.g., performing activities in the artificial reality), products, accessories, services, or a combination thereof. Artificial reality systems that provide artificial reality content can be implemented on a variety of platforms, including HMDs connected to host computer systems, stand-alone HMDs, mobile devices or computing systems, or can provide artificial reality content to one or more views or any other hardware platform.

The methods, systems and devices discussed above are examples. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For example, in alternative configurations, the described methods may be performed in an order different from that described, and/or various stages may be added, omitted, and/or combined. Furthermore, features described with respect to certain embodiments may be combined in various other embodiments. Different aspects and elements of specific embodiments may be combined in similar ways. Additionally, technology evolves, and therefore many components are examples without limiting the scope of this disclosure to those particular examples.

Specific details are given in this description to provide a thorough understanding of specific examples. However, specific examples may be practiced without such specific details. For example, well-known circuits, processes, systems, structures, and techniques have been shown without unnecessary detail so as not to obscure the specific examples. This description provides exemplary specific examples only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the foregoing description of specific examples will provide those skilled in the art with an enabling description for implementing various specific examples. Various changes may be made in the function and arrangement of components without departing from the spirit and scope of the disclosure.

Additionally, some specific examples are described as procedures depicted as flowcharts or block diagrams. Although each may describe operations as a sequential process, many operations may be performed in parallel or concurrently. Additionally, the order of operations can be reconfigured. The procedures may have additional steps not included in the figures. Furthermore, specific examples of methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments that perform the associated tasks may be stored in a computer-readable medium, such as a storage medium. The processor can perform associated tasks.

It will be apparent to those of ordinary skill in the art that substantial changes may be made based on specific requirements. For example, custom or specialized hardware may also be used, and/or particular components may be implemented in hardware, software (including portable software such as applets, etc.), or both. Additionally, connections to other computing devices, such as network input/output devices, may be employed.

Referring to the figures, components that may include memory may include non-transitory machine-readable media. The terms "machine-readable medium" and "computer-readable medium" can refer to any storage medium that participates in providing data that enables a machine to operate in a particular way. In the specific examples provided above, various machine-readable media may be involved in providing instructions/code to a processing unit and/or other device for execution. Additionally or alternatively, machine-readable media may be used to store and/or carry such instructions/code. In many implementations, the computer-readable medium is a physical and/or tangible storage medium. This media can take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Common forms of computer readable media include, for example, magnetic and/or optical media such as compact disks (CDs) or digital versatile disks (DVDs), punched cards, paper tape, any other media with a pattern of holes Physical media, RAM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), FLASH-EPROM, any other memory chip or cassette, a carrier wave as described below, or any other medium that allows a computer to read instructions and/or program code. A computer program product may include program code and/or machine-executable instructions, which may represent a program, function, subroutine, program, routine, application (App), routine, module, software package, class, or Any combination of instructions, data structures, or program statements.

Those of ordinary skill in the art will appreciate that the information and signals used to convey the messages described herein may be represented using any of a variety of different techniques and techniques. For example, data, instructions, commands, information, signals, bits, symbols and chips that may be mentioned throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination thereof.

As used herein, the terms "and" and "or" may include a variety of meanings, which meanings are also intended to depend, at least in part, on the context in which such terms are used. Typically, "or" when used in relation to a list, such as A, B, or C, is intended to mean A, B, and C (here used in an inclusive sense), as well as A, B, or C (here used in an exclusive sense) ). Additionally, as used herein, the term "one or more" may be used to describe any feature, structure, or characteristic in the singular, or may be used to describe some combination of features, structures, or characteristics. It should be noted, however, that this is an illustrative example only and claimed subject matter is not limited to this example. Furthermore, the term "at least one of" when used in connection with a list, such as A, B, or C, may be interpreted to mean any combination of A, B, and/or C, such as A, AB, AC, BC, AA ,ABC,AAB,AABBCCC, etc.

Additionally, although certain specific examples have been described using specific combinations of hardware and software, it should be appreciated that other combinations of hardware and software are possible. Certain embodiments may be implemented in hardware only or in software only, or using a combination thereof. In one example, the software can be implemented by a computer program product containing computer code or instructions that can be executed by one or more processors for performing the steps, operations described in this disclosure. or any or all of the programs, where a computer program may be stored on a non-transitory computer-readable medium. The various programs described herein may be implemented in any combination on the same processor or on different processors.

Where a device, system, component or module is described as being configured to perform certain operations or functions, the electronic circuit may be programmed, for example, by designing the electronic circuit to perform the operation, by programming the programmable electronic circuit, such as a microprocessor, Processor) to perform operations (such as by executing computer instructions or code, or a processor or core programmed to execute code or instructions stored on non-transitory memory media) or any combination thereof this configuration. Programs may communicate using a variety of technologies, including but not limited to conventional technologies for inter-program communication, and different pairs of programs may use different technologies, or the same pair of programs may use different technologies at different times.

Therefore, the description and drawings should be viewed in an illustrative rather than a restrictive sense. It will be apparent, however, that additions, subtractions, deletions, and other modifications and changes may be made to the specification and drawings without departing from the broader spirit and scope as set forth in the claims. Therefore, although specific examples have been described, these examples are not intended to be limiting. Various modifications and equivalents are within the scope of the following patent applications.

102: Body 104: Signal electrode 106: Signal electrode 108: Signal electrode 110: Signal electrode 112: Instrument amplifier 114: Instrument amplifier 116: Instrument amplifier 118: Instrument amplifier 120: Reference electrode 122: Operational amplifier 124: Ground electrode 202: Reference Electrode 204: Reference electrode 206: Reference electrode 208: Reference electrode 210: Operational amplifier 212: Operational amplifier 214: Operational amplifier 216: Operational amplifier 218: Resistor 220: Resistor 222: Resistor 224: Resistor 226: Operational amplifier 302 :Op amp 304:Op amp 306:Op amp 308:Op amp 310:Resistor 312:Resistor 314:Resistor 316:Resistor 350:Resistor 352:Resistor 354:Resistor 356:Resistor 402:Operation Amplifier 404: Op amp 406: Op amp 408: Op amp 410: R _g resistor 412: R _f resistor 414: R _{g resistor} 416: R f resistor 418: R _g resistor 420: R _f resistor 422 : R _g resistor 424: R _f resistor 452: capacitor 454: resistor 456: capacitor 462: capacitor 502: voltage source 504: voltage source 506: voltage source 508: voltage source 600: program 602: block 604: area Block 606: Block 702: Envelope 704: Band portion 706: Reference electrode 708: Signal electrode 710: Signal electrode 712: Signal electrode 714: Signal electrode 716: Signal electrode 720: Reference electrode 722: Signal electrode 724: Signal electrode 726 :Reference electrode 728:Signal electrode 730:Signal electrode 740:Signal electrode 742:Signal electrode 748:Signal electrode 750:Signal electrode 752:Signal electrode 754:Signal electrode 756:Signal electrode 758:Signal electrode 760:Signal electrode 762:Reference Electrode patch 800: Computing system 810: Processor 820: Memory 822: Application module 824: Application module 825: Operating system 826: Virtual reality engine 830: Wireless communication subsystem 832: Wireless link 834: Antenna 840: Bus 850: Camera 860: Display module 870: User input/output module 880: Other hardware modules 890: Sensor

Illustrative specific examples are described in detail with reference to the following drawings. [FIG. 1] is a schematic diagram of an example electrode configuration utilizing a single common reference electrode according to some specific examples. [Fig. 2] is a schematic diagram of an example electrode configuration using multiple reference electrodes to generate a common reference signal according to some specific examples. [FIG. 3A] is a schematic diagram of an example electrode configuration using signal electrodes to generate a common reference signal according to some specific examples. [FIG. 3B] is an example of an implementation of an electrode configuration using signal electrodes to generate a common reference signal according to some specific examples. [FIG. 4A] is a schematic diagram of an example electrode configuration for generating a common reference signal using signals generated from signal electrodes, according to some embodiments. [FIG. 4B] is an example of an implementation of an example electrode configuration that utilizes signals generated from signal electrodes to generate a common reference signal, according to some embodiments. [FIG. 5] is a schematic diagram illustrating the generation of a common reference signal for the example electrode configuration depicted in FIG. 4A according to some specific examples. [Fig. 6] is a flowchart of an example procedure for algorithmically determining a common reference signal according to some specific examples. [FIGS. 7A]-[FIG. 7D] illustrate example electrode placements on a wrist-worn device according to some specific examples. [FIG. 8] is a simplified block diagram of an example of a computing system that may be implemented as part of a mobile device and/or user device, according to certain embodiments. The drawings depict specific examples of the present disclosure for purposes of illustration only. Those of ordinary skill in the art will readily recognize from the following description that alternative embodiments of the illustrated structures and methods may be employed without departing from the principles of the present disclosure or the claimed benefits. In the drawings, similar components and/or features may have the same reference numbers. Additionally, various components of the same type may be distinguished by using a dash after the reference mark and a second mark that distinguishes among similar components. If only a first reference number is used in the specification, the description applies to any of the similar components having the same first reference number regardless of the second reference number.

102:Body

104:Signal electrode

106:Signal electrode

108:Signal electrode

110: Signal electrode

112: Instrument amplifier

114: Instrument amplifier

116: Instrument amplifier

118: Instrument amplifier

120:Reference electrode

122: Operational amplifier

124:Ground electrode

Claims (16)

A device for sensing neuromuscular signals, the device comprising: a wearable structure configured to be worn by a user; a plurality of signal electrodes aligned along an interior portion of the wearable structure and configured to be proximate to the skin surface of the user, each signal electrode of the plurality of signal electrodes being configured to detect neuromuscular signals; A plurality of amplifiers corresponding to the plurality of signal electrodes, wherein one amplifier of the plurality of amplifiers has: a first input operatively coupled to a corresponding signal electrode of the plurality of signal electrodes; a first input two inputs; and one output corresponding to a neuromuscular signal channel; and Circuitry configured to directly or indirectly generate a common-mode reference signal based on signals from at least a subset of the plurality of signal electrodes, wherein the second input of each amplifier of the plurality of amplifiers is configured to receive the common mode reference signal or a signal based on the common mode reference signal, wherein the one or more electrodes are configured to measure signals from the same muscle group as the muscle groups measured by the plurality of signal electrodes. Activity. The device of claim 1, wherein each signal electrode in at least a subset of the plurality of signal electrodes is operatively coupled to a buffer, an output of the buffer corresponding to the common mode reference signal. The device of claim 1, wherein outputs of the plurality of amplifiers corresponding to the at least a subset of the plurality of signal electrodes are operatively coupled via corresponding plurality of resistors to generate the common mode reference signal. For example, the device of claim 1 further includes: One or more analog-to-digital converters (ADCs) that convert the outputs of the plurality of amplifiers into digital outputs; Digital circuitry configured to determine a common-mode digital signal based on the digital outputs; and A digital-to-analog converter (DAC) generates the common-mode reference signal based on the common-mode digital signal. The device of claim 1, wherein the wearable structure includes a wrist wearable structure. The device of claim 1, wherein the plurality of signal electrodes are circumferentially disposed around the interior portion of the wearable structure. The device of claim 1, wherein the same muscle group includes wrist extensor muscles and/or wrist flexor muscles. The device of claim 1, wherein the plurality of signal electrodes aligned along the interior portion of the wearable structure are configured to contact the skin surface of the user. A device for sensing neuromuscular signals, the device comprising: a wearable structure configured to be worn by a user; a plurality of signal electrodes aligned along an interior portion of the wearable structure and configured to be proximate to the skin surface of the user, each signal electrode of the plurality of signal electrodes being configured to detect neuromuscular signals; A plurality of amplifiers corresponding to the plurality of signal electrodes, wherein one amplifier in the plurality of amplifiers has: a first input operatively coupled to a corresponding signal electrode in the plurality of signal electrodes; an inverter a phase input; and an output corresponding to a neuromuscular signal channel; and Circuitry configured to operatively couple outputs of the plurality of amplifiers to generate a common-mode reference signal, wherein the common-mode reference signal is provided to the inverting input of each of the plurality of amplifiers . The apparatus of claim 9, wherein a given output of a given one of the plurality of amplifiers is operatively coupled to the inverting input via one or more resistors. The device of claim 10, further comprising a capacitor in series with a first one of the one or more resistors, wherein the capacitor and the first resistor form a structure configured to attenuate signals from the corresponding electrode A DC offset to a high pass filter. The device of claim 11, further comprising a resistor in parallel with the capacitor, wherein the resistor in parallel with the capacitor acts as a current leakage path. The device of claim 10, further comprising a capacitor in parallel with a second one of the one or more resistors, wherein the capacitor forms a circuit configured to perform anti-frequency overlap of the neuromuscular signal path. part of the low pass filter. The device of claim 9, wherein the wearable structure includes a wrist wearable structure. The device of claim 9, wherein the plurality of signal electrodes are circumferentially disposed around the interior portion of the wearable structure. The device of claim 9, wherein the neuromuscular signals are associated with wrist extensor muscles and/or wrist flexor muscles.