Signal measuring device

Abstract

A signal measurement device (100), comprising: an electrode (110) fitted to a human body for collecting an electromyographic signal of the human body within a target frequency range; the alternating current excitation source (120) is electrically connected with the electrode (110) and is used for providing an excitation signal of a first frequency so as to generate a detection signal reflecting the contact impedance between the electrode (110) and the human body; and a gain circuit (130) for providing gain for the electromyographic signal and the detection signal. The signal measuring device (100) provides gain for the acquired electromyographic signal and detection signal by providing the gain circuit (130), thereby improving the strength and quality of the electromyographic signal and detection signal, so that the signal measuring device (100) can accurately perform monitoring.

Description

A signal measuring device Technical Field

[0001] This specification relates to the field of circuit design, and in particular to a circuit structure of a signal measuring device. Background Art

[0002] Signal measurement devices, widely used in physiological monitoring, disease diagnosis, and experimental research, can acquire data related to a user's physical condition by collecting physiological signals. For example, signal measurement devices can monitor and utilize electromyographic (EMG) signals to clinically diagnose various conditions, including muscle fatigue, myasthenia gravis, myotonia, and muscular dystrophy.

[0003] However, when the signal measurement device collects physiological signals, the contact impedance between the electrodes and the human body often increases due to poor fit between the electrodes and the human body, and the skin is almost insulated in a dry environment, which affects the collection. Or the signal strength generated is low due to the human body's inadequate movement, making the collected physiological signals of poor quality and difficult to monitor accurately.

[0004] Therefore, it is hoped that a device capable of improving the quality of physiological signals can be provided.

[0005] Summary of the Invention

[0006] One embodiment of this specification provides a signal measurement device. The device includes: electrodes, which are attached to the human body and are used to collect myoelectric signals from the human body within a target frequency range; an AC excitation source electrically connected to the electrodes and configured to provide an excitation signal at a first frequency to generate a detection signal reflecting the contact impedance between the electrodes and the human body; and a gain circuit for providing gain to the myoelectric signals and the detection signal.

[0007] In some embodiments, the target frequency range may include 20 Hz-400 Hz, and the first frequency is not less than 250 Hz.

[0008] In some embodiments, the difference between the first frequency and any integer multiple of 50 Hz is not less than 1 Hz; or, the difference between the first frequency and any integer multiple of 60 Hz is not less than 1 Hz.

[0009] In some embodiments, the first frequency is above the target frequency range.

[0010] In some embodiments, the gain of the gain circuit for the electromyographic signal is not less than 1 / 10 of the gain for the detection signal and not more than 10 times the gain for the detection signal.

[0011] In some embodiments, the frequency response of the gain circuit has one or more peaks within a first frequency range, and frequencies within the first frequency range are higher than 50 Hz and lower than the first frequency.

[0012] In some embodiments, a ratio of a gain of the gain circuit at 100 Hz to a gain of the gain circuit at 10 Hz is a first signal-to-noise ratio, and the first signal-to-noise ratio is not less than 4.

[0013] In some embodiments, a ratio of a gain of the gain circuit at 100 Hz to a gain of the gain circuit at 50 Hz is a second signal-to-noise ratio, and the second signal-to-noise ratio is not less than 2.

[0014] In some embodiments, the gain circuit further includes a high-pass filter circuit, which is used to filter the collected electromyographic signals and detection signals.

[0015] In some embodiments, the gain circuit also includes a low-pass filter circuit, which is connected to the high-pass filter circuit, and the low-pass filter circuit is used to filter the high-frequency noise of the electromyographic signal and the detection signal; and the signal measuring device also includes an analog-to-digital converter, which is used to perform analog-to-digital conversion on the filtered electromyographic signal and the detection signal.

[0016] In some embodiments, the sampling rate of the analog-to-digital converter is greater than twice the third frequency, and the third frequency is the larger frequency between the first frequency and the frequency of the electromyographic signal.

[0017] In some embodiments, the ratio of the gain of the gain circuit at 100 Hz to the gain at a second frequency is a third signal-to-noise ratio, the second frequency is a frequency corresponding to 1 / 2 of the sampling rate of the analog-to-digital converter, and the third signal-to-noise ratio is not less than 10.

[0018] In some embodiments, the high-pass filtering circuit includes an active band-pass filter, which is also used to provide a first gain for the electromyographic signal and the detection signal; the low-pass filtering circuit includes a passive low-pass filter, which is coupled to the active band-pass filter.

[0019] In some embodiments, the high-pass filtering circuit includes a fifth-order high-pass filter, the input end of the fifth-order high-pass filter receives the electromyographic signal and the detection signal, and the fifth-order high-pass filter is also used to provide a first gain for the electromyographic signal and the detection signal; the low-pass filtering circuit includes a seventh-order low-pass filter, the seventh-order low-pass filter is coupled with the fifth-order high-pass filter, and the seventh-order low-pass filter is also used to provide a second gain for the electromyographic signal and the detection signal.

[0020] In some embodiments, the fifth-order high-pass filter and the seventh-order low-pass filter are Chebyshev filters.

[0021] In some embodiments, a secondary gain circuit is further provided between the electrode and the high-pass filter circuit, and the secondary gain circuit provides a secondary gain, which is smaller than the first gain and the second gain.

[0022] In some embodiments, the electrode includes a first electrode and a second electrode, which respectively collect the first electromyographic signal and the second electromyographic signal in the electromyographic signal; the AC excitation source includes two excitation sources, which are respectively connected to the first electrode and the second electrode, and respectively provide two excitation signals to generate the first detection signal and the second detection signal in the detection signal; the gain circuit includes a differential amplifier, which differentially amplifies the first electromyographic signal and the second electromyographic signal, and the first detection signal and the second detection signal.

[0023] In some embodiments, the gain circuit provides gain to the electromyographic signal and the detection signal simultaneously; or, the gain circuit provides gain to the electromyographic signal and the detection signal respectively in different time periods.

[0024] In some embodiments, the signal measuring device collects the electromyographic signal and the detection signal simultaneously; or, the signal measuring device collects the electromyographic signal and the detection signal respectively in different time periods.

[0025] In some embodiments, the signal measuring device is a wearable device.

[0026] In the embodiments of this specification, a gain circuit can be set to provide gain for the collected electromyographic signals and detection signals, thereby improving the strength and quality of the electromyographic signals and detection signals, so that the signal measurement device can accurately monitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] This specification will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, like numbers represent like structures, wherein:

[0028] FIG1 is a structural block diagram of a signal measuring device according to some embodiments of this specification;

[0029] FIG2A is a frequency response curve diagram of a signal measurement device according to some embodiments of this specification;

[0030] FIG2B is a logarithmic frequency response curve diagram of a signal measurement device according to some embodiments of this specification;

[0031] FIG3 is a structural block diagram of an exemplary signal measurement device according to some embodiments of this specification;

[0032] 4A-4B are schematic structural diagrams of exemplary high-pass filtering circuits according to some embodiments of this specification;

[0033] 5A-5B are schematic structural diagrams of exemplary low-pass filtering circuits according to some embodiments of this specification;

[0034] FIG6 is a schematic structural diagram of an exemplary secondary gain circuit according to some embodiments of this specification;

[0035] FIG7A is a circuit structure block diagram of a signal measuring device according to Example 1 of some embodiments of this specification;

[0036] FIG7B is a schematic diagram of a circuit structure of a signal measuring device according to Example 1 of some embodiments of this specification;

[0037] FIG8A is a circuit structure block diagram of a signal measuring device according to an exemplary embodiment 2 of some embodiments of this specification;

[0038] FIG8B is a circuit structure diagram of a signal measuring device according to exemplary Example 2 shown in some embodiments of this specification;

[0039] FIG9 is a circuit structure diagram of a bandpass gain signal measuring device according to Example 3 of some embodiments of this specification;

[0040] FIG10 is a frequency response curve diagram of the signal measurement device in FIG7B , FIG8B and FIG9 . DETAILED DESCRIPTION

[0041] To more clearly illustrate the technical solutions of the embodiments of this specification, the following briefly describes the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this specification. Those skilled in the art can apply this specification to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0042] It should be understood that the terms "system," "device," "unit," and / or "module" used herein are a method for distinguishing different components, elements, parts, portions, or assemblies at different levels. However, if other terms can achieve the same purpose, the terms may be replaced by other expressions.

[0043] As used in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not refer to the singular but also include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0044] Flowcharts are used throughout this specification to illustrate the operations performed by systems according to embodiments of this specification. It should be understood that preceding or following operations do not necessarily need to be performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0045] The signal measurement device of one or more embodiments of this specification can be applied to devices that collect one or more physiological signals, such as smart wearable devices, medical detection equipment, or signal analysis equipment. In some embodiments, the smart wearable device can be set in various parts of the human body (for example, calf, thigh, waist, back, chest, shoulder, neck, etc.) to collect physiological signals from various parts of the user's body in different states, and the collected signals can be further processed later. In some embodiments, the smart wearable device may include smart bracelets, smart shoes and socks, smart glasses, smart helmets, smart watches, smart clothes, smart backpacks, smart accessories, etc. or any combination thereof.

[0046] In some embodiments, physiological signals are detectable signals that can reflect the state of the body. For example, physiological signals may include respiratory signals, electrocardiogram (ECG) signals, myoelectric signals, blood pressure signals, temperature signals, and other signals. In some embodiments, the frequency range of the physiological signals may include 0.05 Hz to 2 kHz, wherein the frequency range of the ECG signal may include 0.05 Hz to 100 Hz, and the frequency range of the myoelectric signal may include 10 Hz to 850 Hz.

[0047] In some embodiments, the intensity of the physiological signal collected by the signal measurement device may be affected by a variety of factors, such as the contact impedance between the human body and the electrodes, the degree of activation of the human muscles, etc. In some embodiments, the contact impedance is the impedance generated by the contact between the human skin and the electrodes of the signal measurement device, and its impedance value may be affected by the dryness of the skin of the human body in contact with the resistor and the contact state of the human body with the skin. For example, the drier the skin, the greater the impedance value of the contact impedance, resulting in a worse quality of the collected physiological signal; conversely, the wetter the skin, the smaller the impedance value of the contact impedance, and the better the quality of the collected physiological signal. For another example, poor contact between the human body and the skin will cause the impedance value of the contact impedance to increase, resulting in a worse quality of the physiological signal. In some embodiments, the degree of muscle activation is the active state of the muscle when working, which can affect the intensity of the myoelectric signal released by the muscle. For users, there are many daily exercise monitoring needs (such as walking, standing, etc.). Compared with fitness monitoring needs (such as squats, running, etc.), daily exercise has a low degree of muscle activation, which will result in a low myoelectric intensity, affecting subsequent recognition and processing.

[0048] In some embodiments, in order to improve the intensity and quality of the collected physiological signals (such as electromyographic signals), a detection signal corresponding to the contact impedance can be obtained in advance, so as to detect the size of the contact impedance to evaluate the quality of the physiological signal. In some embodiments, a gain can also be provided for the electromyographic signal and the detection signal, thereby increasing the intensity of the electromyographic signal and the detection signal so that the electromyographic signal can be read at high resolution later. The signal measurement device provided in the embodiment of the present application is described in detail below, taking the electromyographic signal as an example.

[0049] In some embodiments, if the user wears the electrodes incorrectly or their skin is too dry during the EMG signal acquisition process, the contact impedance between the body and the electrodes can be high, resulting in the intensity of the collected EMG signals being too low, making it difficult to accurately monitor the user's physiology. Furthermore, in some embodiments, if the muscle activation level of the muscles to be monitored is insufficient during the signal acquisition process, the EMG signals generated by the muscles can also be too low, making it difficult for the signal acquisition device to identify and process the EMG signals.

[0050] Therefore, according to some embodiments of the present application, a detection signal reflecting the contact impedance between the human body and the electrode can be collected simultaneously with the EMG signal, so that the contact impedance can be adjusted appropriately and high-quality EMG signals can be collected. Appropriate gain is then provided for the EMG signal and the detection signal to ensure high-resolution reading, recognition, and processing of the EMG signal.

[0051] FIG1 is a block diagram of a signal measuring device according to some embodiments of this specification. As shown in FIG1 , the signal measuring device 100 may include: an electrode 110, an AC excitation source 120, and a gain circuit 130. The electrode 110 is electrically connected to the AC excitation source 120, and the gain circuit 130 is electrically connected to the electrode 110 and the AC excitation source 120, respectively. In some embodiments, the electrode 110 can collect myoelectric signals of a human body within a target frequency range; the AC excitation source 120 is used to provide an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the electrode 110 and the human body; and the gain circuit 130 is used to provide gain for the myoelectric signals and the detection signals.

[0052] The electrode 110 can be a circuit element that inputs or outputs electric current through contact. In some embodiments, the electrode 110 can be fitted to the human body to collect physiological signals of the human body (such as electromyographic signals, ECG signals, blood pressure signals, etc.). In some embodiments, the electrode 110 can collect electromyographic signals of the human body within a target frequency range. In some embodiments, electromyographic signals are physiological signals generated by human muscles, which can reflect the activity state of human neuromuscular system. In some embodiments, the target frequency range can include the frequencies of most of the electromyographic signals generated by muscles, and can also include the frequencies at which the electromyographic signals desired to be obtained are located.

[0053] In some embodiments, under external stimulation (e.g., an excitation signal), a detection signal corresponding to electrode 110 may also be generated. This detection signal may reflect the contact impedance between electrode 110 and the human body. In some embodiments, the detection signal may be a signal reflecting the magnitude of the contact impedance and, accordingly, may be used to reflect the quality of the electromyographic signal. By analyzing the detection signal corresponding to a single electrode, or the difference in detection signals between multiple electrodes, the quality of the electromyographic signal collected by a single electrode or multiple electrodes can be evaluated. For example, if the detection signal corresponding to a particular electrode indicates that the contact impedance between the electrode and the human body is greater than a certain threshold, this means that the electrode is not worn correctly or the user's skin is too dry. For another example, if the difference between the detection signals corresponding to two electrodes is large, this indicates that the difference in contact impedance between the two electrodes and the human body is large, which means that at least one of the electrodes is not worn correctly or the user's skin is too dry, and the quality of the collected electromyographic signal is poor. Conversely, if the difference between the detection signals corresponding to the two electrodes is small, this indicates that the difference in contact impedance between the two electrodes and the human body is small, and the quality of the collected electromyographic signal is good. In some embodiments, the detection signal may also reflect other information such as the user's electrode wearing status, body composition information, and skin condition.

[0054] In some embodiments, electrodes 110 can be attached to different parts of the human body to collect physiological signals from different parts of the body. For example, electrodes 110 can be attached to the user's chest, wrists, back, legs, arms, head, etc. In some embodiments, there can be one or more electrodes. For example, one electrode can be used to collect signals from one part of the body, while two electrodes can be used as a group to collect myoelectric signals from the same part of the body.

[0055] In some embodiments, the electrodes can be in contact with the human body in the form of flexible patches, which can be regular shapes such as circular, oval, rectangular, diamond, or other irregular shapes. In some embodiments, the electrodes can be made of metallic conductive materials (e.g., copper, aluminum, nickel, chromium, alloys, etc.), non-metallic conductive materials (e.g., conductive plastic, conductive rubber, conductive silicone, conductive fabric), or other conductive materials.

[0056] In some embodiments, the signal measuring device 100 may further include one or more reference ground electrodes (not shown in FIG1 ), which may serve as a reference ground for the signal measuring device 100. In some embodiments, the one or more reference ground electrodes may be configured to conform to the human body, allowing the excitation signal generated by the AC excitation source 120 to flow through the human body to the reference ground electrodes, forming a closed loop. In some embodiments, the one or more reference ground electrodes may be positioned on a flat and relatively stable (less active) area, such as the back or head, to effectively reduce noise.

[0057] The AC excitation source 120 can be a circuit element that provides electrical energy. In some embodiments, the AC excitation source 120 can provide an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the electrode 110 and the human body. In some embodiments, the AC excitation source 120 can be a current source or a voltage source. By way of example only, the excitation signal can be understood as flowing through the electrode 110 and the human body to form a closed loop. In this case, the detection signal can correspond to the voltage division of the contact impedance between the electrode 110 and the human body within this closed loop. The higher the AC excitation source intensity, the easier it is to detect the detection signal. It should also be noted that the AC excitation source intensity should also be considered in consideration of the human body's safe voltage or current to ensure human safety. The AC excitation source intensity should not be too high. In some embodiments, the current intensity of the AC excitation source can be less than 1 mA. Furthermore, in some embodiments, the current intensity of the AC excitation source can be less than 100 μA. Furthermore, in some embodiments, the current intensity of the AC excitation source can be 10 μA.

[0058] In some embodiments, there can be one AC excitation source 120, which can be connected to multiple electrodes 110 via multiple branches to provide excitation signals to the multiple electrodes 110, wherein each branch can be provided with one electrode 110. In some embodiments, there can be multiple AC excitation sources 120, each of which can be connected to one or more electrodes 110 to provide an excitation signal to each electrode 110.

[0059] In some embodiments, the AC excitation source 120 can simultaneously generate multiple excitation signals with different frequencies, and can provide excitation signals with the same or different frequencies to the multiple electrodes 110, thereby generating detection signals with different frequencies. For example, the AC excitation source 120 can provide excitation signals with different frequencies to the multiple electrodes 110 to collect different detection signals. The multiple electrodes 110 can be spaced a large distance apart (e.g., greater than or equal to 5 cm) so that the closed loop through which the excitation signal flows can pass through different human tissues. With this arrangement, the detection signals of different frequencies corresponding to the multiple electrodes 110 can be used to reflect body composition information of the human body, such as body fat percentage, bone density, body fluid content, and other body composition information. Specifically, the AC excitation source 120 can provide a second excitation signal with a frequency different from the first to generate a second detection signal. The second detection signal can reflect the impedance information of the closed loop formed between each electrode and the human body at another frequency (i.e., a frequency different from the first frequency), including the contact impedance between the electrode and the human body and the impedance of the human tissue in the closed loop. In some embodiments, body composition information of a human body may be determined using a first detection signal generated by a first excitation signal (eg, an excitation signal having a first frequency) and a second detection signal generated by a second excitation signal.

[0060] In some embodiments, the excitation signal may be a voltage signal or a current signal. In some embodiments, the excitation signal may be an AC signal having a first frequency, so that the generated detection signal also has the first frequency. The first frequency may be set within a frequency range that is less susceptible to external interference (e.g., power frequency interference) and less susceptible to interference with the electromyographic signal.

[0061] In some embodiments, a voltage divider impedance may also be provided between the AC excitation source 120 and the electrode 110. Since the electrode 110 and the voltage divider impedance are in the same loop, the detection signal may correspond to the voltage divider of the contact impedance between the electrode 110 and the human body in the closed loop, or the voltage divider impedance in the closed loop. Since the size of the detection signal is affected by the contact impedance between the electrode 110 and the human body, the size of the detection signal may reflect the size of the contact impedance, thereby evaluating the quality of the electromyographic signal. For example, the greater the intensity of the detection signal corresponding to a certain electrode 110, the greater the corresponding contact impedance, which means that the quality of the electromyographic signal collected by the electrode is poor; conversely, if the intensity of the detection signal is smaller, the corresponding contact impedance is smaller, which means that the quality of the electromyographic signal collected by the electrode is better.

[0062] In some embodiments, when the voltage divider impedances corresponding to the two electrodes have the same parameters, the difference in the detection signals corresponding to the two electrodes can reflect the difference in contact impedance with the human skin. For example, the greater the difference between the two detection signals, the greater the difference between the corresponding two contact impedances, and the worse the quality of the corresponding electromyographic signal; conversely, the smaller the difference between the two detection signals, the smaller the difference between the corresponding two contact impedances, and the better the quality of the corresponding electromyographic signal. In this way, by comparing the difference between the detection signals, it can be reflected whether the fit between the two electrodes and the human body is good, and then reflect whether the electromyographic signal collected by the electrode meets the requirements.

[0063] In some embodiments, the target frequency range can be set according to the frequency range of the electromyographic signal desired to be obtained. In some embodiments, the target frequency range can include 10 Hz to 850 Hz. In some embodiments, the target frequency range can include 20 Hz to 400 Hz. In some embodiments, the first frequency can be set according to the frequency range of the detection signal desired to be obtained. In some embodiments, the first frequency can be no less than 250 Hz.

[0064] In some embodiments, the first frequency of the excitation signal can be set according to the target frequency range. In some embodiments, the first frequency can be higher than the target frequency range to avoid most of the frequency bands where the electromyographic signal is located and reduce the mutual interference between the electromyographic signal and the excitation signal. In some embodiments, the first frequency can be no less than 850Hz. In some embodiments, the first frequency can be no less than 400Hz. If the intensity of the excitation signal is large or the contact impedance corresponding to the electrode of the part to be measured can be divided into enough voltage, the electromyographic signal will interfere less with the excitation signal, and the excitation signal (e.g., an excitation signal whose first frequency can be no less than 400Hz) can tolerate a small number of electromyographic signals (e.g., electromyographic signals with a frequency between 400Hz and 850Hz).

[0065] Since the signal acquisition device 100 is also subject to interference from power frequency (e.g., 50 Hz or 60 Hz AC power supply and its harmonics) noise, in some embodiments, the first frequency can also be set according to the frequency range of the power frequency noise. For example, the set first frequency can avoid the influence of power frequency noise to avoid interference from power frequency and its harmonic noise. In some embodiments, the difference between the first frequency and any integer multiple of 50 Hz can be no less than 1 Hz, or the difference between the first frequency and any integer multiple of 50 Hz can be no less than 2%. In some embodiments, the difference between the first frequency and any integer multiple of 60 Hz can be no less than 1 Hz, or the difference between the first frequency and any integer multiple of 60 Hz can be no less than 2%.

[0066] It should be noted that in the process of signal measurement, there are a large number of interference signals in the low frequency band caused by movements such as tiny peristalsis of the head, limbs, jaw, tongue, and swallowing, i.e., motion artifacts (MA). Avoiding setting the first frequency of the excitation signal to a lower frequency can avoid the interference of motion artifacts. In some embodiments, the first frequency can also be set based on the sampling frequency of the subsequent processing circuit to prevent the sampling frequency provided by the processing circuit from failing to meet the effective sampling of the detection signal to ensure the quality of the signal. For a specific description of the relationship between the sampling frequency and the first frequency, please refer to other parts of the specification of this application, such as Figures 2A-2B and their descriptions.

[0067] Gain circuit 130 is a signal processing circuit that can amplify signals. In some embodiments, gain circuit 130 can be used to provide gain for the myoelectric signal and the detection signal. For example, the myoelectric signal and the detection signal can be used as inputs to gain circuit 130, which amplifies them to increase their strength and signal-to-noise ratio, thereby improving their quality.

[0068] It should be noted that the contact impedance between the human body and the electrode may be relatively low at the first frequency, resulting in a low intensity detection signal generated by voltage division, making it difficult to subsequently identify and process the detection signal. In the embodiment of the present application, the gain circuit 130 provides gain for both the electromyographic signal and the detection signal, thereby increasing the intensity of the electromyographic signal and the detection signal and ensuring that the electromyographic signal and the detection signal can be accurately identified and processed subsequently.

[0069] In some embodiments, the gain circuit 130 can provide gain for signals in all frequency bands, and can also provide gain for signals in some frequency bands. Taking electromyographic signals as an example, most electromyographic signals are mainly distributed in the frequency band of 10 Hz to 850 Hz. In this case, the gain circuit 130 can provide gain for electromyographic signals in the frequency band of 10 Hz to 850 Hz to avoid providing gain for other frequency bands (e.g., except the frequency band of 10 Hz to 850 Hz), thereby suppressing noise interference with the electromyographic signals and improving the signal-to-noise ratio of the electromyographic signals.

[0070] In some embodiments, the gain can be expressed as the degree to which the myoelectric signal and the detection signal are amplified. For example, the greater the gain provided by the gain circuit 130, the greater the amplification factor of the myoelectric signal and the detection signal. Conversely, the smaller the gain provided by the gain circuit 130, the smaller the amplification factor of the myoelectric signal and the detection signal.

[0071] In some embodiments, the size of the gain can be set according to the actual signal strength and the expected signal strength. In some embodiments, the size of the gain can be set according to the actual signal strength and the expected signal strength of the electromyographic signal and the detection signal. For example, since the actual signal strength of the electromyographic signal and the detection signal is approximately 10μV and below, under the condition of 3.3V power supply, the resolution of the commonly used 12-bit analog-to-digital converter is approximately 0.8mV (i.e., the expected signal strength), then the gain circuit 130 can be used to provide a gain of more than 100 times to 1,000 times, so that the signal strength of the electromyographic signal and the detection signal after gain can reach 1mV to 10mV.

[0072] In some embodiments, the gain circuit 130 can provide the same or different gains for the electromyographic signal and the detection signal respectively. In some embodiments, the electromyographic signal and the detection signal after gain can be filtered and processed by the same circuit. In order to prevent the gain difference from being too large, resulting in the intensity difference between the electromyographic signal and the detection signal after gain being too large, in some embodiments, the gain of the electromyographic signal by the gain circuit 130 can be no less than 1 / 10 of the gain of the detection signal, and can be no more than 10 times the gain of the detection signal. In other words, the relative value between the gain provided to the electromyographic signal and the gain provided to the excitation signal can be set within 10 times, so as to ensure that the intensity difference between the electromyographic signal and the detection signal after gain is not large, which is convenient for subsequent identification and processing.

[0073] Since the gain circuit 130 needs to provide gain for the myoelectric signal and the excitation signal, the frequency response of the circuit needs to gain not only the myoelectric frequency band but also the excitation source frequency band, while fully suppressing frequencies lower than the myoelectric frequency and higher than the excitation frequency.

[0074] In some embodiments, the frequency response of the gain circuit 130 may have one or more peaks within a first frequency range. The first frequency range referred to herein may include the frequency of the electromyographic signal and the frequency of the detection signal. For example, the first frequency range may be a frequency range with frequencies higher than 50 Hz and lower than the first frequency. Since the gain circuit 130 needs to provide gain for the electromyographic signal and the detection signal separately, in some embodiments, the number of peaks in the frequency response of the gain circuit 130 may be determined based on the frequencies of the electromyographic signal and the detection signal. In some embodiments, the frequency response of the gain circuit 130 may be bimodal, with the two peaks being close to the target frequency range of the electromyographic signal and the first frequency, respectively. In some alternative embodiments, the frequency response of the gain circuit 130 may have only one peak with a relatively wide bandwidth within the first frequency range, and has a higher gain for frequencies within the first frequency range than for other frequency bands, thereby suppressing signals with frequencies lower than the electromyographic signal and / or higher than the excitation signal, thereby reducing interference with the electromyographic signal and the excitation signal.

[0075] Taking the AC excitation source providing an excitation signal with two frequencies (such as the aforementioned first excitation signal and the second excitation signal) as an example, if the frequencies of the first excitation signal and the second excitation signal are 620Hz and 820Hz respectively, the frequency response of the gain circuit 130 can be designed to have a peak with a width covering 51Hz to 820Hz in the first frequency range, or it can be designed to have two peaks with widths covering 51Hz to 400Hz and 620Hz to 820Hz respectively in the first frequency range, or to have three peaks with widths covering 51Hz to 400Hz, around 620Hz, and around 820Hz respectively in the first frequency range, so as to ensure that a larger gain can be provided for the electromyographic signal in the target frequency range and each detection signal. For the structure of the gain circuit 130 for achieving different frequency responses, reference can be made to other parts of the specification of this application, such as Figures 4A to 6 and their descriptions.

[0076] FIG. 2A is a frequency response curve diagram of the gain circuit 130 according to some embodiments of the present disclosure, and FIG. 2B is a logarithmic frequency response curve diagram of the gain circuit 130 according to some embodiments of the present disclosure.

[0077] Referring to Figures 2A-2B, curve 210 exhibits a bimodal shape, and its logarithmic conversion to curve 220 exhibits a bandpass shape with a relatively flat passband. Curve 210 has two peaks (peak 211 and peak 212 shown in Figure 2A). Peak 211 is located near 183 Hz, corresponding to a gain of 1160 times; peak 212 is located near 873 Hz, corresponding to a gain of 664.3 times. Curve 210 indicates that gain circuit 130 can provide a gain of greater than 900 times for myoelectric signals within the frequency range of approximately 100 Hz to 300 Hz, and a gain of 100 to 700 times for signals within the frequency range of approximately 800 Hz to 1000 Hz (for example, the detection signal can be set to 820 Hz). In some embodiments, the gain requirement can be determined based on the strength obtained after contact impedance voltage division (i.e., the strength of the detection signal), thereby adjusting the gain provided by gain circuit 130. For example, the gain provided by the gain circuit 130 can be adjusted within a range from (133 times, 1000 Hz) to (664.3 times, 873 Hz).

[0078] The signal measurement process is plagued by numerous interference signals, such as the aforementioned motion artifacts, power frequency and its harmonics, and aliasing noise. On the one hand, providing excessive gain for these interference signals can cause the amplified interference signal to exceed the circuit's measurement range, leading to circuit saturation and data loss, making it difficult to recover the data through the algorithm. On the other hand, providing excessive gain for high-frequency noise can cause high-frequency noise exceeding the sampling rate to be aliased due to sampling rate limitations. This raises the noise floor, causing the high-frequency noise to overlap with the EMG signal, making it difficult to distinguish and process.

[0079] In order to suppress the gain provided by the gain circuit 130 to the aforementioned interference signal, in some embodiments, the gain signal-to-noise ratio can be adjusted to limit the gain of the gain circuit 130 to the frequency corresponding to the interference signal. The gain signal-to-noise ratio can be the ratio of the gain at the frequency of the electromyographic signal to the gain at the frequency of the interference signal. In some embodiments, the gain signal-to-noise ratio can include one or more of the following: motion artifact (MA) signal-to-noise ratio, power frequency signal-to-noise ratio, and aliasing signal-to-noise ratio. The three aforementioned gain signal-to-noise ratios are introduced below.

[0080] In some embodiments, the gain at 10 Hz can be expressed as the gain of motion artifacts, and the ratio of the gain of gain circuit 130 at 100 Hz to the gain at 10 Hz can be a first signal-to-noise ratio (i.e., the aforementioned MA signal-to-noise ratio). To improve the gain signal-to-noise ratio of gain circuit 130, the first signal-to-noise ratio can be set to no less than 4. Taking curve 210 shown in FIG. 2A as an example, the gain at 100 Hz is approximately 940 times, and the gain at 10 Hz is approximately 0.00186, so the first signal-to-noise ratio can be 505376.

[0081] In some embodiments, the gain at 50 Hz can be used to represent the gain of the power frequency noise. The ratio of the gain of the gain circuit 130 at 100 Hz to the gain at 50 Hz can be a second signal-to-noise ratio (i.e., the aforementioned power frequency signal-to-noise ratio). To improve the gain signal-to-noise ratio of the gain circuit 130, the second signal-to-noise ratio can be no less than 2. Taking the curve 210 shown in FIG. 2A as an example, the gain at 100 Hz is approximately 940 times, and the gain at 50 Hz is approximately 8.26, so the second signal-to-noise ratio can be 114.

[0082] In some embodiments, since the generation of aliasing noise is related to the sampling rate, the frequency of the aliasing noise can be expressed as 1 / 2 of the sampling rate of the analog-to-digital converter, also called the second frequency. For example, when the sampling frequency is 4 kHz, the frequency of the aliasing noise can be 2 kHz. The ratio of the gain of the gain circuit 130 at 100 Hz to the gain at the second frequency can be a third signal-to-noise ratio (i.e., the aforementioned aliasing signal-to-noise ratio). In order to improve the gain signal-to-noise ratio of the gain circuit 130, the third signal-to-noise ratio can be no less than 10. Taking the curve 210 shown in Figure 2A as an example, the gain at 100 Hz is approximately 940 times, and the gain at 2 kHz is approximately 0.185, then the third signal-to-noise ratio can be 5081.

[0083] It should be noted that the gain signal-to-noise ratio can also be used to measure the quality of the gain circuit. A higher gain signal-to-noise ratio of the signal measuring device indicates better strength and quality of the acquired electromyographic signal, and a higher quality of the gain circuit.

[0084] In an embodiment of the present application, by adjusting the gain signal-to-noise ratio, it is possible to avoid providing excessive gain to the interference signal, thereby avoiding data loss due to the interference signal after gain exceeding the measurement range of the circuit. It can also reduce the possibility of high-frequency noise overlapping with the electromyographic signal, and improve the quality of the electromyographic signal and the detection signal, so that the electromyographic signal and the detection signal can be read at high resolution later.

[0085] In some embodiments, the gain circuit 130 can provide gain to both the EMG signal and the detection signal. Correspondingly, in some embodiments, the signal measurement device 100 can simultaneously acquire the EMG signal and the detection signal. That is, the signal acquisition device 100 can simultaneously receive the EMG signal and the detection signal as input signals and provide gain to both signals. In this way, the detection signal can reflect the contact impedance between the human body and the electrode in real time, thereby enabling timely determination of the quality of the EMG signal.

[0086] In some embodiments, the signal measuring device 100 can separately collect the electromyographic signal and the detection signal during different time periods. Correspondingly, the gain circuit 130 can separately provide gain for the electromyographic signal and the detection signal during different time periods. For example, the signal measuring device 100 can collect the electromyographic signal during a first time period and provide gain for it via the gain circuit 130. The signal measuring device 100 can collect the detection signal during a second time period and provide gain for the detection signal via the gain circuit 130. For example, the signal measuring device 100 can include a switching circuit that can be connected to the electrode 110. The switching circuit can be used to control the conductive state between the electrode 110 and the gain circuit 130, and can also be used to control the conductive state between the electrode 110 and the AC excitation source 120, so that only the electrode 110 and the gain circuit 130 remain electrically conductive at any given time, or only the electrode 110 and the AC excitation source 120 remain electrically conductive. In this way, by time-sharing the collection and processing of the detection signal and the electromyographic signal, it is possible to reduce the processing pressure on the device and conserve computing resources while avoiding signal interference.

[0087] It should be noted that in some other embodiments, the signal measurement device 100 may collect the electromyographic signal and the detection signal in a time-sharing manner and then simultaneously provide gain to the electromyographic signal and the detection signal using the gain circuit 130. Alternatively, the signal measurement device 100 may collect the electromyographic signal and the detection signal simultaneously and then simultaneously provide gain to the electromyographic signal and the detection signal using the gain circuit 130. In some embodiments, the choice of time-sharing or simultaneous signal collection and processing may be made based on signal quality and device resources.

[0088] In some embodiments, the gain circuit 130 may include a multi-stage amplifier sub-circuit, which is used to perform multi-stage amplification processing on the input signal (such as the electromyographic signal and the detection signal) to achieve the function of providing gain. In some embodiments, the amplifier sub-circuit can be independently set in the signal measuring device 100, such as the secondary gain circuit mentioned elsewhere in this specification. In some embodiments, the amplifier sub-circuit can also be set as a component in a circuit with other functions, and set as a whole with the circuit with other functions, while achieving other functions. It can also provide gain, such as the gain provided by the high-pass filter circuit and the low-pass filter circuit elsewhere in this specification. In some embodiments, different stages of the amplifier sub-circuit in the multi-stage amplifier sub-circuit can have different amplification gains for the input signal. For example, the gain of the amplifier sub-circuit located in the front stage (such as the secondary gain provided by the secondary gain circuit) can be less than the gain located in the back stage (such as the first gain provided by the high-pass filter circuit 140 or the second gain provided by the low-pass filter circuit 150). For the specific structural description of the amplifier sub-circuit, reference can be made to other parts of the specification of this application, such as Figures 5A-6 and their descriptions.

[0089] In some embodiments, the gain circuit 130 may further perform signal processing on the electromyographic signal and the detection signal.

[0090] In some embodiments, the gain circuit 130 may be a structural module having certain signal processing functions, such as amplification, rectification, A / D conversion, filtering, logic processing, etc. In some embodiments, the gain circuit 130 may include a processor (not shown in FIG. 3 ), such as a digital signal processing (DSP) chip, a central processing unit (CPU), a microcontroller unit (MCU), etc.

[0091] As an example only, in some embodiments, the gain circuit 130 can process the detection signal corresponding to a certain electrode separately and use this to evaluate the electromyographic signal collected by the electrode. For example, the gain circuit 130 can amplify the detection signal corresponding to the electrode 110, and then use an analog-to-digital converter to perform analog-to-digital (A / D) conversion on it. The detection signal can separately reflect the contact impedance between the electrode 110 and the human body, thereby reflecting the fit state of the electrode 110 and the human body, thereby determining the quality of the electromyographic signal.

[0092] In some embodiments, the processor can combine the detection signals corresponding to the multiple electrodes to comprehensively evaluate the electromyographic signals collected by these electrodes. For example, the processor can perform operational amplification (e.g., differential amplification) on the detection signals corresponding to the multiple electrodes 110, and then perform analog-to-digital (A / D) conversion on the amplified results. The detection signal after differential amplification can comprehensively reflect the difference in contact impedance between the two electrodes and the human body, thereby reflecting whether the two electrodes are well fitted with the human body, thereby determining the quality of the electromyographic signal.

[0093] In some embodiments, the gain circuit 130 may further filter the detection signal corresponding to the electrode 110 to distinguish the electromyographic signal collected by the electrode 110. In some embodiments, the gain circuit 130 may directly calculate the difference between the detection signals corresponding to the first electrode 111 and the second electrode 112, and then evaluate the electromyographic signal based on the difference. In some embodiments, the evaluation of the electromyographic signal by the gain circuit 130 may include determining the quality of the electromyographic signal and evaluating the fit between one or more electrodes 110 and the human body. In some embodiments, the gain circuit 130 may further determine whether to output the electromyographic signal based on the evaluation result of the electromyographic signal. In some embodiments, the gain circuit 130 may further output a user instruction based on the evaluation result of the electromyographic signal to instruct the user to execute commands such as adjusting the wearing state of the electrode or instructing the user to continue warming up, so as to improve the quality of the electromyographic signal collected subsequently. In some embodiments, the gain circuit 130 may also perform signal processing on the electromyographic signal using a signal processing algorithm (e.g., signal filtering, wavelet transform, machine learning, etc.) to improve the quality of the electromyographic signal.

[0094] In some embodiments, the gain circuit 130 may further include a transceiver circuit, such as a voice input and output circuit, a display circuit, a wireless / wired communication circuit, etc., and the evaluation results of the electromyographic signals collected by the aforementioned electrodes by the gain circuit 130 may be output through the transceiver circuit. In some embodiments, the gain circuit 130 may transmit the electromyographic signals and / or the evaluation results of the electromyographic signals to other terminals via a wired or wireless method (e.g., Bluetooth, WiFi, etc.), and output them through the other terminals (e.g., displayed on a display screen or broadcasted through a speaker).

[0095] It should be noted that the transceiver circuit can be set as a circuit component in the gain circuit 130 and connected to the processor to transmit data and signals; it can also be integrated in the processor so that the processor can realize input and output functions through built-in communication components.

[0096] In some embodiments, the gain circuit 130 may also evaluate the human body state based on the detection signals of multiple different frequencies. For example, the gain circuit 130 may determine body composition information reflecting the human body state, such as body fat percentage, bone density, body fluid content, etc., based on the detection signals of multiple different frequencies.

[0097] It should be noted that the processing functions of the gain circuit 130 may include but are not limited to the above-mentioned contents. For example, in some embodiments, the gain circuit 130 may also calculate the sum of the detection signals corresponding to the multiple electrodes 110, and then evaluate the aforementioned physiological signal based on the sum. In some cases, considering that evaluating the electromyographic signal based on the difference of the detection signals (or the value after differential amplification by an operational amplifier) ​​can better reflect the quality of the electromyographic signal than evaluating based on the sum of the detection signals, the embodiments of this specification mainly use the difference of the detection signals (or the value after differential amplification by an operational amplifier) ​​as an example to illustrate the signal measuring device 100.

[0098] FIG3 is a block diagram of an exemplary signal measurement device 100 according to some embodiments of this specification. As shown in FIG3 , the gain circuit 130 may further include a high-pass filter circuit 140 , which may be connected to the electrode 110 .

[0099] The high-pass filter circuit 140 can be a circuit structure for performing high-pass filtering on the signal. In some embodiments, the high-pass filter circuit 140 can be used to filter low-frequency interference signals in the electromyographic signal and the detection signal, such as low-frequency noise such as motion artifacts and power frequency noise. In some embodiments, the high-pass filter circuit 140 can allow signals higher than the first cut-off frequency (such as the electromyographic signal and the detection signal) to pass through, and prevent interference signals lower than or equal to the first cut-off frequency from passing through, thereby filtering the signal. In some embodiments, the first cut-off frequency can be set according to the frequency of the electromyographic signal and the detection signal, or according to the frequency of the low-frequency noise to be filtered. In some embodiments, the first cut-off frequency can be less than or equal to the frequency in the target frequency range and the lowest frequency in the first frequency. For example, if the target frequency range corresponding to the electromyographic signal is 20Hz to 400Hz and the first frequency of the detection signal is 250Hz, the first cut-off frequency can be less than or equal to 20Hz. In some embodiments, the first cut-off frequency can be greater than or equal to the highest frequency among the frequency of the motion artifact and the power frequency. If the frequency range of the motion artifact, the power frequency and its harmonics is 10 Hz to 50 Hz, the first cutoff frequency may be greater than 50 Hz.

[0100] In some embodiments, the high-pass filter circuit 140 can be replaced with a band-pass filter circuit. Similarly, the bandwidth frequency range of the band-pass filter circuit can be related to the frequency of the electromyographic signal and the detection signal, or the frequency of the low-frequency noise. For example, the bandwidth frequency range of the band-pass filter circuit can include frequencies in the target frequency range and the first frequency, and can also have no intersection with the frequency range of motion artifacts and power frequency noise.

[0101] In the embodiment of the present application, by setting up a high-pass filter circuit 140, low-frequency noise such as motion artifacts, power frequency and its harmonics can be filtered out in a timely manner, avoiding the gain circuit 130 from providing gain for low-frequency noise with higher intensity, and ensuring that the signal after gain does not exceed the measurement range.

[0102] In some embodiments, the amplifier subcircuit (not shown in FIG. 3 ) in the high-pass filter circuit 140 can also provide a first gain for the electromyographic signal and the detection signal to implement a gain function. In some embodiments, the first gain can be a partial gain provided to the electromyographic signal and the detection signal. In some embodiments, the magnitude of the first gain can be adjusted by adjusting the component parameters (e.g., the size of the capacitor and the resistor) in the high-pass filter circuit 140.

[0103] Several examples of the high-pass filter circuit 140 are provided below, and specific implementations of the high-pass filter circuit 140 are described in detail.

[0104] 4A-4B are schematic diagrams of an exemplary high-pass filter circuit 140 according to some embodiments of this specification. In some embodiments, the high-pass filter circuit 140 may include a fifth-order high-pass filter 410, the input of which is coupled to the electrode 110 to filter the electromyographic signal and the detection signal as input.

[0105] As shown in FIG4A , a fifth-order high-pass filter 410 may include operational amplifiers U2A-U2B, resistors R1-R2, R4-R8, and capacitors C1-C3 and C7-C10. The non-inverting input of operational amplifier U2A may be connected to capacitors C1-C3 connected in series. The non-inverting input of operational amplifier U2A may also be connected to power supply VCC2 via resistor R2. The inverting input of operational amplifier U2A may be connected to the output of operational amplifier U2A via resistor R6, and the inverting input of operational amplifier U2A may also be connected to power supply VCC2 via resistor R5. The power supply of operational amplifier U2A is connected to power supply VCC, and the ground of operational amplifier U2A is grounded. The non-inverting input of operational amplifier U2B may be connected to the output of operational amplifier U2A via capacitors C7-C8 connected in series, and the inverting input of operational amplifier U2B may be connected to the output of operational amplifier U2B. The power supply and ground of operational amplifier U2B are left unconnected.

[0106] In some embodiments, the fifth-order high-pass filter 410 is also used to provide a first gain for the electromyographic signal and the detection signal. In some embodiments, the operational amplifier U2A and the operational amplifier U2B can provide a first gain for the input signal (such as, electromyographic signal and detection signal). Wherein, the size of the first gain can be related to the parameters of the resistors R1-R2, R4-R8, and the capacitors C1-C3, C7-C8. In some embodiments, after the fifth-order high-pass filter 410 has filtered the electromyographic signal and the detection signal, a first gain can be provided. In some embodiments, the output terminal of the operational amplifier U2B can be used to output the electromyographic signal and the detection signal after high-pass filtering and partial gain.

[0107] One end of resistor R1 can be connected to the connection point of capacitors C1 and C2, and the other end of resistor R1 can be connected to virtual ground VCC2 to increase the circuit voltage so that the electromyographic signal and detection signal are greater than 0V, so that they can be read by the subsequent analog-to-digital converter. One end of resistor R4 can be connected to the connection point of capacitors C2 and C3, and the other end of resistor R4 can be connected to the output of operational amplifier U2A. One end of resistor R7 can be connected to the non-inverting input of operational amplifier U2B, and the other end of resistor R7 can be connected to virtual ground VCC2. One end of resistor R8 can be connected to the inverting input of operational amplifier U2B, and the other end of resistor R8 can be connected to the non-inverting input of operational amplifier U2B. Capacitor C10 and capacitor C9 are connected in parallel, with one end of each connected to power supply VCC and the other end connected to ground. Capacitors C10 and C9 can be used to filter out noise from power supply VCC.

[0108] In some embodiments, the fifth-order high-pass filter 410 can use operational amplifier U2A and operational amplifier U2B to perform high-pass filtering on the detection signal and the electromyographic signal. In some embodiments, the first cutoff frequency of the fifth-order high-pass filter 410 can be adjusted by adjusting the component parameters of operational amplifier U2A and operational amplifier U2B. In some embodiments, the fifth-order high-pass filter 410 can be a Chebyshev filter. The Chebyshev filter attenuates faster in the transition band than other filters (such as Butterworth filters). The frequency response curve of the Chebyshev filter is closer to the frequency response curve of the ideal filter, and has a better filtering effect.

[0109] In some embodiments, the high-pass filter circuit 140 may include an active band-pass filter 420 , and an input end of the active band-pass filter 420 may be coupled to the electrode 110 to filter the electromyographic signal and the detection signal as input.

[0110] As shown in FIG4B , the active bandpass filter 420 may include operational amplifiers U2A-U2B, resistors R4, R6-R7, and capacitors C1, C7-C11. The non-inverting input of the operational amplifier U2A may be connected to a virtual ground VCC2. The inverting input of the operational amplifier U2A may be connected to a capacitor C1 and a resistor R4 connected in series. The inverting input of the operational amplifier U2A may also be connected to the output of the operational amplifier U2A via a capacitor C8 and a resistor R7 connected in parallel. The power supply of the operational amplifier U2A may be connected to the power supply VCC, and the ground terminal of the operational amplifier U2A may be grounded. The inverting input of the operational amplifier U2B may be connected to the output of the operational amplifier U2A via a resistor R6 and a capacitor C11 connected in series. The non-inverting input of the operational amplifier U2B may be connected to the virtual ground VCC2. The inverting input terminal of the operational amplifier U2B can be connected to the output terminal of the operational amplifier U2A through the parallel capacitors C7 and R5, and the power supply terminal and the ground terminal of the operational amplifier U2B are left unconnected.

[0111] In some embodiments, similar to the high-pass filter 410 described above, the active band-pass filter 420 is also used to provide a first gain for the electromyographic signal and the detection signal. In some embodiments, the operational amplifier U2A and the operational amplifier U2B of the active band-pass filter 420 can provide a first gain for the input signal (e.g., the electromyographic signal and the detection signal). The magnitude of the first gain can be related to the parameters of the resistors R4 and R7, and the capacitors C1 and C8. In some embodiments, the first gain can be provided after the active band-pass filter 420 has filtered the electromyographic signal and the detection signal.

[0112] In some embodiments, similar to the high-pass filter 410 described above, the output of operational amplifier U2B of active bandpass filter 420 can be used to output the EMG signal and detection signal after bandpass filtering and partial gain. Capacitors C10 and C9 are connected in parallel, with one end of each connected to the power supply VCC and the other end connected to ground.

[0113] In some embodiments, the active bandpass filter 420 can perform bandpass filtering on the electromyographic signal and the detection signal using resistors R4, R5-R7, and capacitors C1, C7-C8, and C11. In some embodiments, the bandwidth frequency range of the active bandpass filter 420 can be adjusted by adjusting the component parameters of the resistors R4, R5-R7, and capacitors C1, C7-C8, and C11.

[0114] Continuing to refer to FIG3 , in some embodiments, the gain circuit 130 may include: a low-pass filter circuit 150 , which is connected to the high-pass filter 140 , and is used to filter high-frequency noise in the electromyographic signal and the detection signal.

[0115] The low-pass filter circuit 150 can also be a circuit structure for performing low-pass filtering on the signal. In some embodiments, the low-pass filter circuit 150 can be used to filter the higher-frequency interference signals in the electromyographic signal and the detection signal, such as high-frequency noise such as aliasing noise. In some embodiments, the low-pass filter circuit 150 can allow signals below the second cut-off frequency (such as, electromyographic signal and detection signal) to pass through, and prevent interference signals higher than or equal to the second cut-off frequency from passing, thereby achieving filtering of the signal. Similar to the above-mentioned high-pass filter circuit 140, in some embodiments, the second cut-off frequency can be set according to the frequency of the electromyographic signal and the detection signal, or it can be set according to the frequency of the high-frequency noise to be filtered. In some embodiments, the second cut-off frequency can be greater than or equal to the frequency in the target frequency range and the highest frequency in the first frequency. In some embodiments, the second cut-off frequency can be less than or equal to 1 / 2 of the sampling rate.

[0116] In an embodiment of the present application, by sequentially setting up a signal processing architecture of high-pass filtering and low-pass filtering, and providing gain during the high-pass filtering and low-pass filtering processes, on the one hand, it is possible to timely suppress low-frequency noise while avoiding providing gain for low-frequency signals with greater intensity, thereby preventing the gained signal from exceeding the measurement range and causing data loss, thereby improving the stability of signal acquisition; on the other hand, the architecture of first gain and then low-pass filtering can filter the high-frequency noise introduced during signal amplification, thereby avoiding the introduction of aliasing noise in the subsequent analog-to-digital conversion process.

[0117] In some embodiments, the amplifying subcircuit in the low-pass filter circuit 150 can also provide a second gain for the electromyographic signal and the detection signal to achieve a gain function. In some embodiments, the second gain can be a partial gain provided to the electromyographic signal and the detection signal. In some embodiments, the size of the second gain can be adjusted by adjusting the component parameters in the low-pass filter circuit 150 (such as the size of the capacitor and the resistor, etc.). In some embodiments, the components that provide the second gain in the low-pass filter circuit 150 can be set at the first stage of the low-pass filter circuit 150 so that the signal is first gained and then low-pass filtered.

[0118] Several examples of the low-pass filter circuit 150 are provided below, and specific implementations of the low-pass filter circuit 150 are described in detail.

[0119] Figures 5A-5B are schematic diagrams of exemplary low-pass filter circuits according to some embodiments of this specification. In some embodiments, the low-pass filter circuit 150 may include a seventh-order low-pass filter 510, the input of which is coupled to the high-pass filter circuit 140 to filter the amplified electromyographic signal and the detection signal as inputs.

[0120] As shown in FIG5A , the seventh-order low-pass filter 510 may include operational amplifiers U3A-U3C, resistors R9-R12, R16-R20, and capacitors C11-C15, C17, and C19. The non-inverting input of the operational amplifier U3A may be connected to the series-connected resistors R9-R11. The non-inverting input of the operational amplifier U3A may also be connected to the virtual ground VCC2 via resistor R12. The inverting input of the operational amplifier U3A may be connected to the output of the operational amplifier U3A via resistor R16. The power supply of the operational amplifier U3A may be connected to the power supply VCC, and the ground of the operational amplifier U3A may be grounded. The non-inverting input of the operational amplifier U3B may be connected to the output of the operational amplifier U3A via the series-connected resistors R16 and R18. The inverting input of the operational amplifier U3B may be connected to the output of the operational amplifier U3B. The power supply and ground of the operational amplifier U3B may be left unconnected. The non-inverting input terminal of the operational amplifier U3C can be connected to the output terminal of the operational amplifier U3B through the series resistors R19-R20, the inverting input terminal of the operational amplifier U3C can be connected to the output terminal of the operational amplifier U3C, and the power supply terminal and the ground terminal of the operational amplifier U3C are left unconnected.

[0121] In some embodiments, the amplification subcircuit in the seventh-order low-pass filter 510 can provide a second gain for the input signal. In some embodiments, the operational amplifiers U3A-U3C can provide a second gain for the input signal (e.g., the myoelectric signal and the detection signal after the first gain). The size of the second gain can be related to the parameters of the resistors R9-R12, R16-R20, and the capacitors C11-C15, C17, and C19. In some embodiments, the output end of the operational amplifier U2C can be used to output the myoelectric signal and the detection signal after low-pass filtering and partial gain (e.g., the second gain).

[0122] One end of capacitor C11 can be connected to the connection point of resistors R9 and R10, and the other end of capacitor C11 can be connected to virtual ground VCC2. One end of capacitor C13 can be connected to the connection point of resistors R10 and R11, and the other end of capacitor C13 can be connected to the output of operational amplifier U3A. One end of capacitor C14 can be connected to the non-inverting input of operational amplifier U3B, and the other end of capacitor C14 can be connected to virtual ground VCC2. One end of capacitor C15 can be connected to the connection point of resistors R17 and R18, and the other end of capacitor C15 can be connected to the output of operational amplifier U3B. One end of capacitor C17 can be connected to the non-inverting input of operational amplifier U3C, and the other end of capacitor C17 can be connected to virtual ground VCC2. One end of capacitor C19 can be connected to the connection point of resistors R19 and R20, and the other end of capacitor C19 can be connected to the output of operational amplifier U3C.

[0123] In some embodiments, the seventh-order low-pass filter 510 can use operational amplifiers U3A-U3C to perform low-pass filtering on the detection signal and the electromyographic signal. In some embodiments, the second cutoff frequency of the seventh-order low-pass filter 510 can be adjusted by adjusting the component parameters of the operational amplifiers U3A-U3C.

[0124] Similar to the aforementioned fifth-order high-pass filter 410 , in some embodiments, the seventh-order low-pass filter 510 may also be a Chebyshev filter.

[0125] In some embodiments, the low-pass filter circuit 150 may include a passive low-pass filter 520 , the input end of which is coupled to the high-pass filter circuit 140 to filter the amplified electromyographic signal and the detection signal as inputs.

[0126] As shown in FIG5B , the passive low-pass filter 520 may include resistors R1-R2, R8-R9, and capacitors C2-C3, C12-C13. Resistors R8-R9, R2, and R1 are connected in series, and one end of capacitors C2-C3 and C12-C13 are connected to a virtual ground VCC2. The other end of capacitor C12 is connected to the connection point of resistors R8-R9, the other end of capacitor C13 is connected to the connection point of resistors R9 and R2, the other end of capacitor C2 is connected to the connection point of resistors R2 and R1, and the other end of capacitor C3 is connected to resistor R1.

[0127] In some embodiments, the end of resistor R8 away from resistor R9 can be used to receive the myoelectric signal and detection signal after gain, and the end of resistor R1 away from resistor R2 can be used to output the myoelectric signal and detection signal after low-pass filtering. In some embodiments, the passive low-pass filter 520 includes four RC low-pass filtering units. Exemplarily, the passive low-pass filter 520 may include capacitor C12-resistor R8, capacitor C13-resistor R9, capacitor C2-resistor R2, and capacitor C3-resistor R1. In some embodiments, the passive low-pass filter 520 can utilize the aforementioned RC low-pass filtering unit to perform low-pass filtering on the detection signal and the myoelectric signal. In some embodiments, the second cut-off frequency of the passive low-pass filter 520 can be adjusted by adjusting the component parameters in the aforementioned RC low-pass filtering unit.

[0128] In the embodiment of the present application, since the passive low-pass filter 520 does not require additional power supply (such as power supply VCC), the aliasing noise that may be introduced by the passive low-pass filter 520 is relatively small, thereby improving the quality of the electromyographic signal and the detection signal.

[0129] It should be noted that the passive low-pass filter 520 may not provide gain (e.g., second gain) for the input signal (e.g., the electromyographic signal and the detection signal after the first gain), but instead utilizes the amplifying sub-circuit in the aforementioned active band-pass filter 420 to provide a first gain for the electromyographic signal and the detection signal to achieve a gain function. In some embodiments, a second gain may also be provided by separately providing an active amplifying sub-circuit at the input end of the passive low-pass filter 520 to achieve a gain function. In addition, the aforementioned various filters (e.g., fifth-order high-pass filter 410, active band-pass filter 420, seventh-order low-pass filter 510, passive low-pass filter 520) are all examples, and the types, structures, and parameters of the filter components can be adjusted according to filtering requirements and gain requirements.

[0130] In some embodiments, a secondary gain circuit (not shown in FIG3 ) may be further provided between the electrode 110 and the high-pass filter circuit 140 . The secondary gain circuit provides a secondary gain that is smaller than the first gain and the second gain.

[0131] In some embodiments, the secondary gain circuit can be an independently configured amplifier subcircuit that provides secondary gain for the electromyographic signal and the detection signal to achieve a gain function. In some embodiments, the secondary gain can provide partial gain for the electromyographic signal and the detection signal. In some embodiments, the secondary gain can be adjusted by adjusting the component parameters (e.g., the size of the capacitor and resistor) in the secondary gain circuit.

[0132] In some embodiments, the secondary gain circuit can provide a secondary gain of 1 to 1000 times. In some embodiments, the secondary gain circuit is located before other amplifying sub-circuits, and the gain provided by the secondary gain circuit can be smaller than the gain provided by other amplifying sub-circuits. In some embodiments, the secondary gain circuit can provide a secondary gain of 10 times.

[0133] FIG6 is a schematic diagram of an exemplary secondary gain circuit 610 according to some embodiments of this specification. As shown in FIG6 , in some embodiments, the secondary gain circuit 610 may include an operational amplifier U1, wherein the non-inverting input and the inverting input of the operational amplifier U1 are respectively connected to electrodes to receive the electromyographic signal and the detection signal as input signals. The power supply terminal of the operational amplifier U1 is connected to the power supply VCC, and the ground terminal of the operational amplifier U1 is grounded. The reference terminal of the operational amplifier U1 is connected to the virtual ground VCC2, and the output terminal of the operational amplifier U1 is used to output a gained signal. The value of the gained signal may be equal to the difference between the output terminal of the operational amplifier U1 and the reference terminal.

[0134] The first gain control terminal and the second gain control terminal of operational amplifier U1 can be connected via resistor R3. In some embodiments, the resistance of resistor R3 corresponds to the amplification factor of operational amplifier U1. In some embodiments, the secondary gain provided by secondary gain circuit 610 to the input signal can be adjusted by adjusting the resistance of resistor R3. For example, increasing the resistance of resistor R3 can decrease the secondary gain; conversely, decreasing the resistance of resistor R3 can increase the secondary gain.

[0135] In some embodiments, operational amplifier U1 can be a differential amplifier or an instrumentation amplifier, such as an amplifier, so that operational amplifier U1 has a high input impedance, which can reduce the variation of the input signal when the circuit is connected. In some embodiments, secondary gain circuit 610 has a high input impedance, which can reduce the variation of the signal when the circuit is connected, making the acquired detection signal more stable.

[0136] 3 , in some embodiments, the signal detection device 100 may further include an analog-to-digital converter 160 . The analog-to-digital converter 160 may be connected to the low-pass filter circuit 150 , and the analog-to-digital converter 160 is used to perform analog-to-digital conversion on the filtered electromyographic signal and the detection signal.

[0137] In some embodiments, the analog-to-digital converter 160 can sample the electromyographic signal and the detection signal according to the sampling rate to generate a digital signal corresponding to the electromyographic signal and the detection signal. In some embodiments, the sampling rate of the analog-to-digital converter 160 can be set in combination with the frequency of the AC excitation source (i.e., the first frequency). Specifically, in order to collect the electromyographic signal and the detection signal of the target frequency, the sampling rate of the analog-to-digital converter 160 can be greater than 2 times the third frequency, wherein the third frequency is the larger frequency between the first frequency and the maximum target frequency of the electromyographic signal. In order to reduce errors, in some embodiments, the sampling rate can be 4 times or more of the third frequency. It should be noted that due to the large number of channels of the signal measuring device 100, most circuits find it difficult to support extremely high sampling rates of multiple channels, so the single-channel sampling rate and the first frequency of the AC excitation source should not be too high. For example, the first frequency can be 1kHz and the single-channel sampling rate can be 8kHz.

[0138] Since the electromyographic signal and the detection signal are processed simultaneously, the electromyographic signal and the detection signal are mixed together. In some embodiments, the signal detection device 100 may further include a digital circuit (not shown in FIG3 ) located at the output end of the analog-to-digital converter 160, which is used to extract and separate the electromyographic signal after analog-to-digital conversion and the detection signal after analog-to-digital conversion. In some embodiments, the signal detection device 100 may further include a second low-pass filter circuit and a second high-pass filter circuit located at the output end of the analog-to-digital converter 160. The second low-pass filter circuit can be used to extract the electromyographic signal after analog-to-digital conversion, and the second high-pass filter circuit can be used to extract the detection circuit after analog-to-digital conversion.

[0139] In the embodiment of the present application, by extracting the electromyographic signal and the detection signal separately, the detection signal can be used alone to more accurately evaluate the quality of the electromyographic signal and the fit between the electrode and the human body.

[0140] In some embodiments, the electrode 110 may include a first electrode and a second electrode, respectively collecting a first electromyographic signal and a second electromyographic signal in the electromyographic signal. The AC excitation source 130 includes two excitation sources (e.g., a first AC excitation source and a second AC excitation source), respectively connected to the first electrode and the second electrode, and respectively providing two excitation signals (e.g., a first excitation signal and a second excitation signal) to generate a first detection signal and a second detection signal in the detection signal. Correspondingly, the gain circuit 130 includes a differential amplifier, respectively performing differential amplification on the first electromyographic signal and the second electromyographic signal, and on the first detection signal and the second detection signal.

[0141] In some embodiments, the frequencies of the first excitation signal and the second excitation signal provided by the AC excitation source 120 can be different, resulting in different frequencies of the generated first detection signal and the second detection signal. In some embodiments, the first electrode and the second electrode can be separated by a relatively large distance (e.g., greater than or equal to 5 cm) so that the closed loops through which the first excitation signal and the second excitation signal flow can pass through different human tissues. This results in the first detection signal and the second detection signal having different frequencies corresponding to the first electrode and the second electrode, respectively, being used to reflect body composition information.

[0142] In some embodiments, the first excitation signal and the second excitation signal provided by AC excitation source 120 may each include multiple frequencies, so that the generated first detection signal and the second detection signal also include corresponding multiple frequencies. In this way, by performing operational amplification on the first detection signal and the second excitation signal, human impedance information at different frequencies can be obtained, thereby reflecting body composition information.

[0143] In some embodiments, the frequencies of the first excitation signal and the second excitation signal provided by the AC excitation source 120 may also be the same, so that the frequencies of the generated first detection signal and the second detection signal are also the same, thereby simultaneously obtaining multiple detection signals and multiple electromyographic signals so as to timely evaluate and feedback the signals.

[0144] In an embodiment of the present application, a detection signal reflecting the contact impedance can be collected while collecting the electromyographic signal to evaluate the electromyographic signal. Subsequently, the contact impedance can be adjusted appropriately so that a higher quality electromyographic signal can be collected, and gain can be provided for the electromyographic signal and the detection signal. Even if the signal strength is small, the strength and quality of the electromyographic signal can be improved through gain to ensure subsequent recognition and processing of the electromyographic signal.

[0145] In some embodiments, the signal measuring device 100 can be applied to a wearable device. In some embodiments, the wearable device may include a smart bracelet, smart shoes and socks, smart glasses, smart helmets, smart watches, smart clothing, smart backpacks, smart accessories, etc. or any combination thereof. Taking smart clothing (such as fitness clothes or sportswear) as an example, the signal measuring device 100 can obtain the physiological signals collected by any two or two electrodes with a specific association (for example, two electrodes attached to the same muscle to receive the electromyographic signals of the same muscle), and evaluate the quality of the physiological signal based on the difference between the physiological signals collected by the any two electrodes or the two electrodes with a specific association, or evaluate the fit between the any two or two electrodes with a specific association and the human body.

[0146] In some embodiments, the signal measurement device 100 can also perform wearing status analysis, warm-up status analysis, size fit analysis, clothing life analysis, motion monitoring, skin condition analysis, body composition analysis, etc. based on the evaluation results of the aforementioned physiological signals.

[0147] Three exemplary signal measurement devices are provided below, and specific implementation methods of the signal measurement devices are described in detail.

[0148] Example 1:

[0149] FIG7A is a circuit structure block diagram of a signal measurement device according to Example 1 shown in some embodiments of this specification. FIG7B is a circuit structure schematic diagram of a signal measurement device according to Example 1 shown in some embodiments of this specification. As shown in FIG7A-7B, this embodiment provides a signal measurement device 700, which may include: an electrode, an AC excitation source (not shown in the figure), a secondary gain circuit 720, an active bandpass filter 730, a passive low-pass filter 740, and an analog-to-digital converter 750. The electrode may include a first electrode 711 and a second electrode 712, the first electrode 711 and the second electrode 712 are respectively connected to the secondary gain circuit 720, and the secondary gain circuit 720, the active bandpass filter 730, the passive low-pass filter 740, and the analog-to-digital converter 750 are connected in sequence.

[0150] In some embodiments, the first electrode 711 and the second electrode 712 (as shown in FIG7B as the function generator XFG1 and the function generator XFG2) can respectively collect electromyographic signals and send them to the secondary gain circuit 720. The AC excitation source can provide an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the first electrode 711 and the second electrode 712 and the human body. In some implementations, the structure and function of the first electrode 711 and the second electrode 712 can be the same as or similar to the above-mentioned electrode 110. For the specific implementation of the electrodes, reference can be made to other parts of the present application specification, such as FIG1-FIG6 and their descriptions.

[0151] The input of secondary gain circuit 720 receives the electromyographic signal and the detection signal and provides secondary gain. In some implementations, the structure and function of secondary gain circuit 720 can be the same as or similar to the secondary gain circuit 610 described above. For the specific implementation of secondary gain circuit 720, please refer to other parts of this application specification, such as Figure 6 and its description.

[0152] The active bandpass filter 730 receives the electromyographic signal and the detection signal from the secondary gain circuit 720, extracts the electromyographic signal and the detection signal according to a preset bandwidth frequency range to filter out low-frequency noise in the signal, avoids subsequent gain provision for the low-frequency noise, and ensures that the signal does not exceed the measurement range of the signal measuring device 700.

[0153] In some embodiments, the amplifier subcircuit in the active bandpass filter 730 can also provide a first gain for the filtered electromyographic signal and the detection signal. Both the secondary gain circuit 720 and the amplifier subcircuit can implement a gain function, providing a secondary gain and a first gain for the electromyographic signal and the detection signal to improve signal quality. In some implementations, the structure and function of the active bandpass filter 730 can be the same or similar to the active bandpass filter 420 described above. For the specific implementation of the active bandpass filter 730, reference can be made to other parts of this specification, such as FIG. 4B and its description.

[0154] In some embodiments, the passive low-pass filter 740 can receive the electromyographic signal and the detection signal from the active band-pass filter 730, and after the electromyographic signal and the detection signal are amplified, the high-frequency noise in the electromyographic signal and the detection signal is filtered out according to the second cut-off frequency, so as to avoid introducing high-frequency noise in the amplification process to improve the quality of the signal. In some implementations, the structure and function of the passive low-pass filter 740 can be the same or similar to the above-mentioned passive low-pass filter 520. The specific implementation of the active band-pass filter 730 can refer to other parts of the specification of this application, such as Figure 5B and its description.

[0155] In some embodiments, an analog-to-digital converter 750 (such as the analog-to-digital converter XSC1 shown in Figure 7B) can receive the electromyographic signal and the detection signal from the passive low-pass filter 740 and perform analog-to-digital conversion on them. In some embodiments, the electromyographic signal and the detection signal after the analog-to-digital conversion can also be processed by a filter to extract the electromyographic signal and the detection signal respectively so that the electromyographic signal and the detection signal can be evaluated subsequently. In some implementations, the structure and function of the analog-to-digital converter 750 can be the same or similar to the above-mentioned analog-to-digital converter 160. The specific implementation of the analog-to-digital converter 750 can refer to other parts of the specification of this application, such as Figures 1-6 and their descriptions.

[0156] 7B , in some embodiments, the passive low-pass filter 740 and analog-to-digital converter 750 assembly may further include a follower U2C, which may be used to maintain output voltage or current stability and isolate the passive low-pass filter 740 from the analog-to-digital converter 750. The non-inverting input of the follower U2C is connected to the output of the passive low-pass filter 740 for receiving electromyographic signals and detection signals, the inverting input of the follower U2C is connected to the output of the follower U2C, and the power supply and ground terminals of the follower U2C are left unconnected.

[0157] 7B , in some embodiments, the signal measuring apparatus 700 may further include a spectrum analyzer XBP1 for measuring the frequency response curve of the signal measuring apparatus 700. One end of the spectrum analyzer XBP1 is connected to the function generator XFG1 and the function generator XFG2 (i.e., the first electrode and the second electrode), respectively, and the other end of the spectrum analyzer XBP1 is connected to the output end of the follower U2C.

[0158] Continuing with FIG. 7B , in some embodiments, signal measuring device 700 may further include a power supply circuit 760. Power supply circuit 760 may be connected to power supply VCC. An output terminal of power supply circuit 760 may be connected to virtual ground VCC2 to provide power to virtual ground VCC2. In some embodiments, when power supply VCC is 3.3V, power supply circuit 760 may provide a 1.65V power supply or another power supply voltage within a dynamic range for virtual ground VCC2.

[0159] In some embodiments, the power supply circuit 760 may include an operational amplifier U2D, wherein the non-inverting input terminal of the operational amplifier U2D is connected to the power supply VCC through a resistor R14, and the non-inverting input terminal of the operational amplifier U2D is also grounded through a resistor R13 and a capacitor C18 connected in parallel. The inverting input terminal of the operational amplifier U2D is connected to the output terminal of the operational amplifier U2D through a resistor R15, and the output terminal of the operational amplifier U2D is grounded through a capacitor C16. Exemplarily, the impedance value of the resistors R13-R14 can be 10kΩ, the impedance value of the resistor R15 can be 300Ω, the capacitive reactance value of the capacitor C16 can be 10μF, the capacitive reactance value of the capacitor C18 can be 10μF, and the model of the operational amplifier U2D can be TLC2274ACPW.

[0160] Example 2:

[0161] FIG8A is a circuit structure block diagram of a signal measuring device according to exemplary example 2 shown in some embodiments of this specification; FIG8B is a circuit structure schematic diagram of a signal measuring device according to exemplary example 2 shown in some embodiments of this specification.

[0162] As shown in Figures 8A-8B, this embodiment provides a signal measurement device 800, which may include: electrodes, an AC excitation source (not shown), a secondary gain circuit 820, a fifth-order high-pass filter 830, a seventh-order low-pass filter 840, and an analog-to-digital converter 850. The electrodes may include a first electrode 811 and a second electrode 812, each of which is connected to the secondary gain circuit 820. The secondary gain circuit 820, the fifth-order high-pass filter 830, the seventh-order low-pass filter 840, and the analog-to-digital converter 850 are connected in sequence.

[0163] In some embodiments, the first electrode 811 and the second electrode 812, the AC excitation source, the secondary gain circuit 820 and the analog-to-digital converter 850 in this embodiment are similar to the first electrode 711 and the second electrode 712, the AC excitation source, the secondary gain circuit 720 and the analog-to-digital converter 750 in the above example one. The specific implementation method can refer to the above example one and will not be repeated here.

[0164] In some embodiments, the fifth-order high-pass filter 830 can receive the electromyographic signal and the detection signal from the secondary gain circuit 820 and filter low-frequency noise in the electromyographic signal and the detection signal according to the first cutoff frequency to avoid providing gain to the low-frequency noise and ensure that the signal does not exceed the measurement range of the signal measurement device 800. In some embodiments, the amplification subcircuit in the fifth-order high-pass filter 830 can also provide a first gain for the filtered electromyographic signal and the detection signal.

[0165] In some embodiments, the structure and function of the fifth-order high-pass filter 830 may be the same as or similar to the fifth-order high-pass filter 410. For the specific implementation of the fifth-order high-pass filter 830, reference may be made to other parts of this specification, such as FIG. 4A and its description.

[0166] In some embodiments, the seventh-order low-pass filter 840 can receive the electromyographic signal and the detection signal from the fifth-order high-pass filter 830. After the electromyographic signal and the detection signal are amplified, the high-frequency noise in the electromyographic signal and the detection signal is filtered out according to the second cutoff frequency, thereby avoiding the introduction of high-frequency noise during the amplification process to improve the signal quality. In some embodiments, the amplification subcircuit in the seventh-order low-pass filter 840 can also provide a second gain for the electromyographic signal and the detection signal before filtering. By first amplifying and then filtering, the aliasing signal generated in the gain can be suppressed, thereby improving the quality of the electromyographic signal and the detection signal.

[0167] In some implementations, the structure and function of the seventh-order low-pass filter 840 may be the same as or similar to the seventh-order low-pass filter 510. For the specific implementation of the seventh-order low-pass filter 840, please refer to other parts of this specification, such as FIG. 5A and its description.

[0168] In some embodiments, the secondary gain circuit 820, the amplifying sub-circuit in the fifth-order high-pass filter 830, and the amplifying sub-circuit in the seventh-order low-pass filter 840 can all implement gain functions, providing secondary gain, first gain, and second gain for the electromyographic signal and the detection signal to improve the signal quality.

[0169] 8B , in some embodiments, a follower U2C may be further provided between the seventh-order low-pass filter 840 and the analog-to-digital converter 750. The follower U2C in this embodiment is similar to the follower U2C in the first example above. The specific implementation thereof may refer to the first example above and will not be further described here.

[0170] In some embodiments, the signal measuring apparatus 800 may further include a spectrum analyzer XBP1 and a power supply circuit 860. The spectrum analyzer XBP1 and the power supply circuit 860 in this embodiment are similar to the spectrum analyzer XBP1 and the power supply circuit 760 in the first example above. The specific implementation method can be referred to the first example above and will not be repeated here.

[0171] Example 3:

[0172] FIG9 is a circuit structure diagram of a bandpass gain signal measuring device according to Example 3 of some embodiments of this specification;

[0173] As shown in FIG9 , this embodiment provides a bandpass gain signal measurement device 900, which may include: electrodes, an AC excitation source (not shown), a secondary gain circuit 920, a bandpass gain circuit 930, and an analog-to-digital converter 950. The electrodes may include a first electrode 911 and a second electrode 912, each of which is connected to the secondary gain circuit 920. The secondary gain circuit 920, the bandpass gain circuit 930, and the analog-to-digital converter 950 are connected in sequence.

[0174] In some embodiments, the first electrode 911 and the second electrode 912, the AC excitation source, the secondary gain circuit 920 and the analog-to-digital converter 950 in this embodiment are similar to the first electrode 711 and the second electrode 712, the AC excitation source, the secondary gain circuit 720 and the analog-to-digital converter 750 in the above example one. The specific implementation method can refer to the above example one and will not be repeated here.

[0175] In some embodiments, the bandpass gain circuit 930 can receive the electromyographic signal and the detection signal from the secondary gain circuit 920, extract the electromyographic signal and the detection signal according to the third bandwidth frequency range, and filter out low-frequency noise and high-frequency noise in the signal, thereby improving the quality of the electromyographic signal and the detection signal to a certain extent. In some embodiments, the third bandwidth frequency range can include the frequency range in which the electromyographic signal and the detection signal are located. In some embodiments, the amplifier subcircuit in the bandpass gain circuit 930 can also provide a third gain for the filtered electromyographic signal and the detection signal.

[0176] Referring to FIG9 , in some embodiments, the bandpass gain circuit 930 may include an operational amplifier U2A, resistors R1-R2, R4, and R7, and capacitors C1 and C8. The non-inverting input of the operational amplifier U2A may be connected to a virtual ground VCC2. The inverting input of the operational amplifier U2A may be connected to a capacitor C1 and a resistor R4 connected in series, and the inverting input of the operational amplifier U2A may also be connected to the output of the operational amplifier U2A via a capacitor C8 and a resistor R7 connected in parallel. The power supply terminal of the operational amplifier U2A is connected to the power supply VCC, and the ground terminal of the operational amplifier U2A is grounded. The series resistors R1-R2 are provided at the output of the operational amplifier U2A.

[0177] In some embodiments, the operational amplifier U2A of the bandpass gain circuit 930 can provide a third gain for the input signal (e.g., an electromyographic signal and a detection signal). The magnitude of the third gain can be related to the parameters of the resistors R4 and R7, and the capacitors C1 and C8. In some embodiments, the third bandwidth frequency range of the bandpass gain circuit 930 can also be adjusted by adjusting the component parameters of the aforementioned resistors R4 and R7, and capacitors C1 and C8.

[0178] For example, the capacitive reactance of capacitor C1 can be 1 μF, the capacitive reactance of capacitor C8 can be 33 nF. The impedance of resistors R1-R2 can be 500 Ω, the impedance of resistor R4 can be 680 Ω, and the impedance of resistor R7 can be 30 kΩ. The power supply VCC can be 3.3 V, and the operational amplifiers U2A and U2B can be TLC2274ACPW.

[0179] In some embodiments, the amplifying sub-circuits in the secondary gain circuit 920 and the bandpass gain circuit 930 can both implement a gain function, providing secondary gain and tertiary gain for the electromyographic signal and the detection signal to improve signal quality.

[0180] 9 , in some embodiments, a follower U2C may be further provided between the bandpass gain circuit 930 and the analog-to-digital converter 950. The follower U2C in this embodiment is similar to the follower U2C in the first example above. The specific implementation thereof may refer to the first example above and will not be further described here.

[0181] In some embodiments, the signal measuring apparatus 900 may further include a spectrum analyzer XBP1 and a power supply circuit 960. The spectrum analyzer XBP1 and the power supply circuit 960 in this embodiment are similar to the spectrum analyzer XBP1 and the power supply circuit 760 in the first example above. For specific implementations, reference may be made to the first example above and will not be repeated here.

[0182] Figure 10 is a graph showing the frequency response curves of the signal measurement devices shown in Figures 7B, 8B, and 9. As shown in Figure 10, curve 1010 is the frequency response curve of signal measurement device 700 shown in Figure 7B; curve 1020 is the frequency response curve of signal measurement device 800 shown in Figure 8B; and curve 1030 is the frequency response curve of the gain circuit of signal measurement device 900 shown in Figure 9.

[0183] As shown in FIG10 , curve 1010 has a peak (peak 1021 shown in FIG10 ), which is located approximately around 210 Hz and corresponds to a gain of approximately 1050. Curve 1020 is similar to curve 210 shown in FIG2A , exhibiting a double peak. Curve 1030 has a relatively small overall amplitude, reflecting the relatively low gain provided by signal measurement device 900 for the myoelectric signal and detection signal.

[0184] As shown in Figure 10 , the three gain signal-to-noise ratios of signal measurement device 800 are all improved compared to signal measurement devices 700 and 900. For example, compared to signal measurement device 700, the MA signal-to-noise ratio of signal measurement device 800 is improved by 10,285 times, the power frequency signal-to-noise ratio is improved by 45.8 times, and the aliasing signal-to-noise ratio is improved by 87.7 times. Compared to signal measurement device 900, the MA signal-to-noise ratio of signal measurement device 800 is improved by 75,080.5 times, the power frequency signal-to-noise ratio is improved by 82.44 times, and the aliasing signal-to-noise ratio is improved by 1,315.5 times.

[0185] The beneficial effects that may be brought about by the embodiments of this specification include but are not limited to: (1) when collecting electromyographic signals, the detection signal reflecting the contact impedance can be collected at the same time, so that the contact impedance can be adjusted appropriately to ensure that the electrode fits well with the human body, and high-quality electromyographic signals can be collected; (2) by setting a gain circuit, gain is provided for the collected electromyographic signals and detection signals, thereby improving the strength and quality of the electromyographic signals and detection signals, so that the signal measuring device can accurately monitor.

[0186] While the basic concepts have been described above, it will be apparent to those skilled in the art that the detailed disclosure is merely illustrative and does not limit this specification. Although not explicitly stated herein, various modifications, improvements, and revisions to this specification may be made by those skilled in the art. Such modifications, improvements, and revisions are suggested in this specification and remain within the spirit and scope of the exemplary embodiments of this specification.

[0187] This specification also uses specific terms to describe the embodiments of this specification. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "one embodiment," "an embodiment," or "an alternative embodiment" two or more times in different locations in this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of this specification may be appropriately combined.

[0188] In addition, unless expressly stated in the claims, the order of the processing elements and sequences, the use of alphanumeric characters, or the use of other names described in this specification are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some of the invention embodiments currently considered useful through various examples, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the spirit and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0189] Similarly, it should be noted that, in order to simplify the presentation of this specification and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this specification sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not imply that the subject matter of this specification requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single disclosed embodiment.

[0190] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0191] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, and documents, cited in this specification is hereby incorporated by reference in its entirety. This includes application history documents that are inconsistent with or conflict with the content of this specification, as well as documents (currently or subsequently attached to this specification) that limit the broadest scope of the claims of this specification. It should be noted that if the descriptions, definitions, and / or terminology used in the accompanying materials are inconsistent or conflicting with the content of this specification, the descriptions, definitions, and / or terminology used in this specification will control.

[0192] Finally, it should be understood that the embodiments described in this specification are intended only to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly described and illustrated in this specification.

Claims

1. A signal measuring device, comprising: Electrodes, the electrodes being attached to a human body and used to collect myoelectric signals of the human body within a target frequency range; an AC excitation source electrically connected to the electrode, for providing an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the electrode and the human body; as well as The gain circuit is used to provide gain for the electromyographic signal and the detection signal.

2. The signal measuring device according to claim 1, characterized in that The target frequency range includes 20 Hz-400 Hz, and the first frequency is not less than 250 Hz.

3. The signal measuring device according to claim 2, characterized in that The difference between the first frequency and any integer multiple of 50 Hz is not less than 1 Hz; or the difference between the first frequency and any integer multiple of 60 Hz is not less than 1 Hz.

4. The signal measuring device according to claim 1, characterized in that The first frequency is higher than the target frequency range.

5. The signal measuring device according to claim 1, characterized in that: The gain of the myoelectric signal by the gain circuit is not less than 1 / 10 of the gain of the detection signal and not more than 10 times the gain of the detection signal.

6. The signal measuring device according to claim 5, characterized in that: The frequency response of the gain circuit has one or more peaks in a first frequency range, and the frequencies in the first frequency range are higher than 50 Hz and lower than the first frequency.

7. The signal measuring device according to claim 5, characterized in that: A ratio of the gain of the gain circuit at 100 Hz to the gain at 10 Hz is a first signal-to-noise ratio, and the first signal-to-noise ratio is not less than 4.

8. The signal measuring device according to claim 5, characterized in that: A ratio of the gain of the gain circuit at 100 Hz to the gain at 50 Hz is a second signal-to-noise ratio, and the second signal-to-noise ratio is not less than 2.

9. The signal measuring device according to claim 5, characterized in that: The gain circuit further includes a high-pass filter circuit, and the high-pass filter circuit is used to filter the collected electromyographic signal and the detection signal.

10. The signal measuring device according to claim 9, characterized in that: The gain circuit further includes a low-pass filter circuit, the low-pass filter circuit is connected to the high-pass filter circuit, and the low-pass filter circuit is used to filter high-frequency noise of the electromyographic signal and the detection signal; and The signal measuring device further comprises an analog-to-digital converter, which is used to perform analog-to-digital conversion on the filtered electromyographic signal and the detection signal.

11. The signal measuring device according to claim 10, characterized in that: The sampling rate of the analog-to-digital converter is greater than twice a third frequency, and the third frequency is a larger frequency between the first frequency and the frequency of the electromyographic signal.

12. The signal measuring device according to claim 10, characterized in that: The ratio of the gain of the gain circuit at 100 Hz to the gain at a second frequency is a third signal-to-noise ratio, where the second frequency is a frequency corresponding to 1 / 2 of the sampling rate of the analog-to-digital converter, and the third signal-to-noise ratio is not less than 10.

13. The signal measuring device according to claim 10, characterized in that: The high-pass filter circuit includes an active band-pass filter, and the active band-pass filter is further used to provide a first gain for the electromyographic signal and the detection signal; The low-pass filtering circuit includes a passive low-pass filter coupled to the active band-pass filter.

14. The signal measuring device according to claim 10, characterized in that: The high-pass filter circuit includes a fifth-order high-pass filter, an input end of the fifth-order high-pass filter receives the electromyographic signal and the detection signal, and the fifth-order high-pass filter is further used to provide a first gain for the electromyographic signal and the detection signal; The low-pass filter circuit includes a seventh-order low-pass filter, which is coupled to the fifth-order high-pass filter. The seventh-order low-pass filter is further configured to provide a second gain for the electromyographic signal and the detection signal.

15. The signal measuring device according to claim 14, characterized in that: The fifth-order high-pass filter and the seventh-order low-pass filter are Chebyshev filters.

16. The signal measuring device according to any one of claims 13 to 15, characterized in that: A secondary gain circuit is further provided between the electrode and the high-pass filter circuit. The secondary gain circuit provides a secondary gain, which is smaller than the first gain and the second gain.

17. The signal measuring device according to claim 1, characterized in that The electrodes include a first electrode and a second electrode, which respectively collect a first electromyographic signal and a second electromyographic signal in the electromyographic signal; The AC excitation source includes two excitation sources, which are respectively connected to the first electrode and the second electrode and provide two excitation signals respectively to generate the first detection signal and the second detection signal in the detection signal; The gain circuit includes a differential amplifier for differentially amplifying the first electromyographic signal and the second electromyographic signal, and the first detection signal and the second detection signal.

18. The signal measuring device according to claim 1, characterized in that The gain circuit provides gain to the electromyographic signal and the detection signal simultaneously; or, the gain circuit provides gain to the electromyographic signal and the detection signal respectively in different time periods.

19. The signal measuring device according to claim 1, characterized in that The signal measuring device collects the electromyographic signal and the detection signal simultaneously; or, the signal measuring device collects the electromyographic signal and the detection signal respectively in different time periods.

20. The signal measuring device according to claim 1, characterized in that The signal measuring device is a wearable device.

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