WO2023029287A1

WO2023029287A1 - Dynamic switching apparatus and dynamic switching method for myoelectricity acquisition reference electrode

Info

Publication number: WO2023029287A1
Application number: PCT/CN2021/137586
Authority: WO
Inventors: 周小猛; 李光林; 杨子健; 邓新平; 李向新; 田岚; 张浩诗
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2021-09-02
Filing date: 2021-12-13
Publication date: 2023-03-09
Also published as: CN113876336A; CN113876336B

Abstract

A dynamic switching apparatus (100) and dynamic switching method for a myoelectricity acquisition reference electrode. The dynamic switching apparatus (100) comprises: several channels of measurement electrodes (11); several channels of programmable gain amplifier circuits (12), positive input terminals of the programmable gain amplifier circuits (12) being connected to output terminals of the measurement electrodes (11); and an external reference electrode (14), which is connected to the programmable gain amplifier circuits (12) by means of a reference electrode dynamic switching circuit (13). When the reference electrode dynamic switching circuit (13) is in a first state, the external reference electrode (14) is connected to negative input terminals of all programmable gain amplifier circuits (12) so as to switch a myoelectricity acquisition reference electrode to the external reference electrode (14). When the reference electrode dynamic switching circuit (13) is in a second state, the positive input terminals of all programmable gain amplifier circuits (12) are connected to the negative input terminals of the programmable gain amplifier circuits (12) after being sampled by a voltage average value to form a negative feedback loop so as to switch the myoelectricity acquisition reference electrode to an average reference electrode.

Description

Dynamic switching device and dynamic switching method of reference electrode for electromyography collection

technical field

The present application relates to the technical field of medical detection, in particular to a dynamic switching device and a dynamic switching method of a reference electrode for myoelectric collection.

Background technique

Human surface electromyography (sEMG) is the comprehensive effect of superficial muscle electromyography and nerve electrical activity on the skin surface, which contains a variety of information about nerve and muscle activity. Collecting, analyzing and processing surface electromyographic signals can obtain information such as the physiological state of the human body, movement intentions, and action patterns. It has important application value in clinical medicine, rehabilitation engineering, and biomechanics, and has been widely used. .

The current multi-channel surface electromyography acquisition equipment can only select one of the external reference electrode or the average reference electrode, and cannot dynamically switch the reference electrode from the hardware. Although some devices can use the software to calculate the average value of all measurement channels as a virtual average reference electrode to realize the analog switching of reference electrodes, but it still needs to first collect the potential of each channel based on the external reference electrode, so it still exists The problem of not being able to collect normally because the input signal is out of range.

Contents of the invention

The present application provides a dynamic switching device and a dynamic switching method for a myoelectric collection reference electrode.

The application provides a dynamic switching device for a myoelectric acquisition reference electrode, the dynamic switching device comprising:

Measuring electrodes for several channels;

A programmable gain amplifier circuit of several channels, the positive input end of the programmable gain amplifier circuit is connected to the output end of the measurement electrode;

An external reference electrode is connected to the programmable gain amplifier circuit through a reference electrode dynamic switching circuit;

Wherein, when the reference electrode dynamic switching circuit is in the first state, the external reference electrode is connected to the negative input terminals of all the programmable gain amplifier circuits, so as to switch the reference electrode for the myoelectric collection to the external reference electrode; When the reference electrode dynamic switching circuit is in the second state, the positive output terminals of all the programmable gain amplifier circuits are connected to the negative input terminals of the programmable gain amplifier circuits after being sampled by the voltage mean value, forming a negative feedback loop, so as to The reference electrode for the EMG acquisition is switched to an average reference electrode.

Wherein, the reference electrode dynamic switching circuit includes a first channel switch of several channels, a second channel switch of several channels, a first switching switch and a second switching switch.

Wherein, when the reference electrode dynamic switching circuit is in the first state, the first channel switch, the second channel switch and the first switching switch of the several channels are closed, and the second switching switch is open, so that the The negative input end of the programmable gain amplifier circuit is connected to the external reference electrode.

Wherein, when the reference electrode dynamic switching circuit is in the second state, the first channel switches and the second switching switches of the several channels are closed, and the second channel switches and the first switching switches of the several channels are off. open, so that the positive output terminals of all the programmable gain amplifier circuits are connected to the negative input terminals of the programmable gain amplifier circuits after being sampled by the voltage mean value, forming a negative feedback loop.

Wherein, the reference electrode dynamic switching circuit also includes current limiting resistors of several channels, the first channel switch, the second channel switch and the current limiting resistors of several channels form a voltage mean value sampling circuit, and the voltage mean value sampling circuit is used for gating The positive output terminal and the negative output terminal of the programmable gain amplifier circuit are connected to the common mode reference point to obtain the average voltage of all gating signals.

Wherein, when the reference electrode dynamic switching circuit is in the third state, the first channel switch and the second channel switch of the target channel are turned off, so as to turn off the measurement electrode corresponding to the target channel.

The application also provides a dynamic switching method of a myoelectric acquisition reference electrode, the dynamic switching method comprising:

Use discrete patch electrodes to collect surface electromyographic signals, where the reference electrode is an external reference electrode;

judging whether the amplitude of the surface electromyographic signal reaches the preset range of the channel;

If so, switching the reference electrode to an average reference electrode through a dynamic switching device;

Wherein, the dynamic switching device is the above-mentioned dynamic switching device.

Wherein, the dynamic switching method also includes:

Obtain the impedance of the measuring electrode based on the surface electromyographic signal of each channel;

judging whether the impedance of the measuring electrode is greater than a preset impedance value;

If yes, ignore the surface electromyographic signal of the channel measuring electrode.

The present application also provides another dynamic switching method of the myoelectric acquisition reference electrode, the dynamic switching method comprising:

Use array patch electrodes to collect surface electromyographic signals, where the reference electrode is an average reference electrode;

judging whether the number of measuring electrodes corresponding to the surface electromyographic signal is less than a preset number;

If so, switching the reference electrode to an external reference electrode through a dynamic switching device;

Wherein, the dynamic switching device is the dynamic switching device according to any one of claims 1-6.

Wherein, the dynamic switching method also includes:

The beneficial effects of the present application are: the dynamic switching device includes: a plurality of channels of measuring electrodes; a programmable gain amplifier circuit, the positive input end of the programmable gain amplifier circuit is connected to the output end of the measuring electrode; an external reference electrode is connected by dynamically switching the reference circuit Programmable gain amplification circuit; wherein, when the dynamic switching reference circuit is in the first state, the external reference electrode is connected to the negative input terminal of the programmable gain amplification circuit to switch the reference electrode of the dynamic switching device to the external reference electrode; the dynamic switching reference circuit In the second state, the positive output end of the programmable gain amplifier circuit is connected to the negative input end of the programmable gain amplifier circuit, so as to switch the reference electrode of the dynamic switching device to the average reference electrode. Through the above method, the dynamic switching device of the present application can realize the dynamic switching of the reference electrode from the hardware.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort. in:

Fig. 1 is the structural representation of an embodiment of the dynamic switching device of the myoelectric acquisition reference electrode provided by the application;

Fig. 2 is the structural representation of another embodiment of the dynamic switching device of the myoelectric acquisition reference electrode provided by the present application;

Fig. 3 is the structure schematic diagram of another embodiment of the dynamic switching device of the myoelectric acquisition reference electrode provided by the present application;

4 is a schematic flow diagram of an embodiment of a method for dynamically switching myoelectric acquisition reference electrodes provided by the present application;

5 is a schematic flow diagram of another embodiment of a method for dynamically switching myoelectric acquisition reference electrodes provided by the present application;

FIG. 6 is a schematic structural diagram of an embodiment of a terminal device provided by the present application;

Fig. 7 is a schematic structural diagram of an embodiment of a computer storage medium provided by the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

Multi-channel surface EMG acquisition equipment usually consists of measuring electrodes, reference electrodes, filtering, programmable gain amplifier (PGA), right leg drive (RLD), analog-to-digital conversion (ADC), data processing and other modules. Among them, the measuring electrodes are used to collect the electromyographic signals of the skin surface, and two kinds of silver-silver chloride discrete patch electrodes and array electrodes integrated on a flexible circuit board (FPC) are usually used. The reference electrode is used to provide a potential reference point. When collecting multi-channel surface electromyography signals, in order to reduce the number of electrode wires, the negative input terminals of all channels are usually connected together to share a reference electrode. In theory, the reference electrode should be selected as the zero potential point of the body or infinity, but this point does not actually exist in the body, and the arms, legs and other tissues that are usually used to measure surface electromyographic signals are not closed like the head Spherical, the reference electrode standardization technology commonly used in EEG acquisition cannot be used to convert the myoelectric potential value based on a specific reference electrode into a potential value referenced to an infinite point in space. Therefore, there are generally two ways to select the reference electrode of the current EMG acquisition equipment: one is to use the external electrode placed on the elbow, knee and other specific parts where the EMG is not active as the reference electrode, that is, the external reference electrode; The reference electrode line is drawn out, but the average value of all measured electrode potentials is calculated by software or hardware, and it is used as the reference electrode, that is, the average reference electrode. The two reference electrodes have their own advantages. The external reference electrode can provide a relatively stable, comparable and reproducible approximate zero potential; the average reference electrode can effectively suppress common-mode interference and reduce the impact on AD by subtracting the average value of all channels. In addition to the requirements of the range and dynamic range of the converter, one electrode wire can also be reduced.

In practical applications, the two reference electrodes currently used have certain limitations:

External reference electrodes are suitable for use with discrete patch electrodes. When working with an array electrode, due to the high density of the array electrode and the small contact surface between a single electrode and the skin, the contact impedance between the array electrode and the reference electrode and the skin is quite different, resulting in a large potential difference between the two, which may exceed the allowable The sEMG waveform cannot be acquired normally due to the programmed gain amplification or the range of the analog-to-digital conversion circuit.

Averaging reference electrodes are suitable for use with array electrodes. When used with a small number or uneven distribution of discrete patch electrodes, the potential of the average reference electrode is not always stable, and may be active and constantly changing over time, which introduces an unknown dynamic potential to all measuring electrodes, As a result, the measured sEMG waveform loses some useful information and cannot be compared with historical or similar data.

Therefore, when using measurement electrodes with different characteristics such as discrete patch electrodes or array electrodes, the multi-channel surface electromyography acquisition device needs to switch between the above two reference electrodes. In some cases, in order to ensure the smooth progress of the EMG acquisition test, it is also necessary to dynamically switch the reference electrode from the hardware. For example, when the input signal exceeds the range due to the drift of the electrode contact impedance during the acquisition process, the external reference electrode needs to be switched to the average Reference electrode: When the number of useful signal channels is too small or the distribution is obviously uneven due to some electrodes falling off or damaged, it is necessary to switch the average reference electrode to an external reference electrode.

In order to solve the problem that the current multi-channel surface electromyography acquisition equipment cannot dynamically switch the reference electrode from the hardware to adapt to different measurement electrodes or measurement environments, this application proposes a new type of dynamic switching device based on the electromyography acquisition reference electrode .

Please refer to FIG. 1 for details. FIG. 1 is a schematic structural diagram of an embodiment of a dynamic switching device for an EMG acquisition reference electrode provided in the present application.

As shown in FIG. 1 , the dynamic switching device 100 for EMG acquisition reference electrodes in the embodiment of the present application at least includes several channels of measuring electrodes 11 , a programmable gain amplifier circuit 12 , a dynamic switching circuit for reference electrodes 13 and an external reference electrode 14 .

Wherein, the positive input end of the programmable gain amplifying circuit 12 is connected to the output end of the measuring electrode 11 , and the external reference electrode 14 is connected to the programmable gain amplifying circuit 12 through the reference electrode dynamic switching circuit 13 .

Specifically, the working state of the reference electrode dynamic switching circuit 13 in the embodiment of the present application is as follows: when the reference electrode dynamic switching circuit 13 is in the first state, the external reference electrode 14 is connected to the negative input terminal of the programmable gain amplifier circuit 12, so that the The reference electrode of the dynamic switching device 100 is switched to the external reference electrode 14; when the reference electrode dynamic switching circuit 13 is in the second state, the positive output terminal of the programmable gain amplifier circuit 12 is connected to the negative input terminals of all programmable gain amplifier circuits 12, Negative feedback is formed to clamp the voltage of the negative input terminal to the average value of the positive input terminal, rather than the average value of the positive output terminal amplified by the programmable gain amplifier circuit 12, so as to switch the reference electrode of the dynamic switching device 100 to the average reference electrode .

Wherein, the reference electrode dynamic switching circuit 13 of the embodiment of the present application specifically includes a first channel switch of several channels, a second channel switch of several channels, a first switching switch and a second switching switch. The number of the first switch and the second switch are both one, and the number of the first channel switch and the second channel switch is consistent with the number of channels of the measuring electrode 11 .

Specifically, the reference electrode dynamic switching circuit 13 is in the first state, that is, the first channel switches of several channels, the second channel switches of several channels, and the first switch are closed, and the second switch is open, so that the programmable gain amplifier circuit The negative input end of 12 is connected to an external reference electrode 14 .

The reference electrode dynamic switching circuit 13 is in the second state, that is, the first channel switches and the second switching switches of several channels are closed, and the second channel switches and the first switching switches of several channels are turned off, so that the positive pole of the programmable gain amplifier circuit 12 The output terminal is connected to the negative input terminal of the programmable gain amplifier circuit 12 .

The reference electrode dynamic switching circuit 13 is in the third state, that is, both the first channel switch and the second channel switch of a certain channel are turned off, so that the measuring electrodes of this channel are short-circuited to shield the surface electromyographic signals measured by the falling off measuring electrodes.

The reference electrode dynamic switching circuit 13 also includes several channels of current-limiting resistors, that is, the number of current-limiting resistors is positively correlated with the number of measuring electrodes. Wherein, the first channel switch, the second channel switch and the current-limiting resistor of several channels can form a voltage mean value sampling circuit, and the voltage mean value sampling circuit can be used to select the positive pole output terminal and the negative pole output terminal of the programmable gain amplifier circuit 12 to the common Model reference point.

The dynamic switching device of the embodiment of the present application includes: measuring electrodes of several channels; a programmable gain amplifier circuit, the positive input end of the programmable gain amplifier circuit is connected to the output end of the measuring electrode; an external reference electrode can be connected through the dynamic switching circuit of the reference electrode. Programmable gain amplification circuit; wherein, when the reference electrode dynamic switching circuit is in the first state, the external reference electrode is connected to the negative input terminal of the programmable gain amplification circuit, so as to switch the reference electrode of the dynamic switching device to the external reference electrode; the reference electrode is dynamically switched When the circuit is in the second state, the positive output end of the programmable gain amplifying circuit is connected to the negative input end of the programmable gain amplifying circuit, so as to switch the reference electrode of the dynamic switching device to the average reference electrode. Through the above method, the dynamic switching device of the present application can realize the dynamic switching of the reference electrode from the hardware.

In the embodiment of the present application, by dynamically switching the external reference electrode and the average reference electrode from the hardware, the existing multi-channel EMG acquisition equipment can be better adapted to different measurement electrodes such as discrete patch electrodes and array electrodes, avoiding the The measured impedance drift is too large to collect the surface electromyographic signal, or the useful information of the surface electromyographic signal is lost due to the small number of measuring electrodes and uneven distribution. Improve the accuracy, data integrity, and efficiency of surface EMG signal acquisition. In addition, the embodiment of the present application cleverly introduces negative feedback into the programmable gain amplifier circuit, and sets the sampling point of the average reference voltage after the programmable gain amplifier circuit, which is the same as the voltage sampling point of the right leg drive circuit, instead of Prior to the programmable gain amplifier circuit in the prior art. This enables the present invention to be easily integrated into existing myoelectric collection devices or chips, and is flexible and convenient to use, reducing the cost of use.

In the following, a specific dynamic switching device will be used to further illustrate the functions realized by the dynamic switching device protected by the embodiment of the present application. Please continue to refer to FIG. 2 . FIG. 2 is a schematic structural diagram of another embodiment of the dynamic switching device for the EMG acquisition reference electrode provided in the present application.

As shown in Figure 2, the dynamic switching device provided by the embodiment of the present application consists of electrodes, filtering, Programmable Gain Amplifier (PGA, Programmable Gain Amplifier), dynamic switching of reference electrodes, right leg driver (RLD, RightLegDriver), analog-to-digital conversion ( ADC, analog to digital converter) circuit. Its core is the reference electrode dynamic switching circuit, and other parts such as electrodes, filters, PGA, RLD and ADC circuits can use the corresponding modules of the existing multi-channel EMG acquisition equipment.

Therefore, the dynamic switching device can be used alone, and can also be integrated into the existing multi-channel myoelectric acquisition equipment and used in conjunction with it.

When used alone, please refer to Figure 2. The electrodes include measurement electrodes, external reference electrodes and right leg drive electrodes, all of which are attached to the surface of the human skin. The measuring electrode is used to collect the electromyographic signal of the skin surface, and the signal is introduced into the positive input terminal of the PGA; the external reference electrode is attached to the approximate zero potential point such as the elbow and knee of the human body to provide a potential reference for each channel, and is introduced into the The negative polarity input terminal of the PGA; the right leg drive electrode is used to establish a closed-loop negative feedback path between the common mode signal of the measurement electrode and the human body to reduce external noise interference.

Among them, the filter circuit is composed of RC low-pass filter, which is used to filter out the high-frequency noise of the input signal from the measurement electrode and the external reference electrode, so as to avoid aliasing in the subsequent analog-to-digital sampling process. The resistance, accuracy and temperature coefficient of the resistors and capacitors of the filter circuits of each channel should be the same to better suppress common-mode interference.

Among them, the PGA circuit is composed of operational amplifiers OPxA, OPxB (x=1,2,...,n) and resistors R1, R2, which are used to amplify the differential mode component of the input signal, suppress the common mode component, and increase the input impedance of the circuit at the same time. UixP and UixN are the positive and negative input terminals of the PGA circuit respectively, and UoxP and UoxN are the positive and negative output terminals of the PGA circuit respectively. The gain of the PGA circuit can be adjusted by adjusting the resistance of R2.

Wherein, the reference electrode dynamic switching circuit is composed of switches SxP, SxN (x=1, 2, . . . , n), SR1, SR2, resistor R3, and operational amplifier OPRA. The switches SxP, SxN and the current-limiting resistor R3 form a voltage average sampling circuit, which is used to gate the signals of the PGA output terminals UoxP and UoxN to the common mode reference point Uc, where Uc is the average value of all gate signals.

If a certain channel is no longer put into use due to reasons such as electrode falling off, the switches SxP and SxN corresponding to the channel should be turned off, which corresponds to the third state in the above-mentioned embodiment.

SxP and SxN are also used together with SR1 and SR2 to realize the function of dynamically switching the reference electrode. The working principle is as follows: close the SxP and SxN of the channel in use, close SR1 at the same time, and open SR2, so that the negative polarity input terminal UixN of the PGA is directly connected to the After filtering, the external reference electrode is connected to realize switching the reference electrode to the external reference electrode, which corresponds to the first state in the above-mentioned embodiment. Close the SxP of the input channel, open SxN, close SR2, and open SR1 at the same time, so that the positive polarity output terminal UoxP of the PGA is connected to the negative polarity input terminal UixN to form a negative feedback, and the voltage of UixN is clamped to the positive polarity input of the PGA The average value of terminal UixP, instead of the average value of UoxP amplified by the PGA, realizes switching the reference electrode to the average reference, which corresponds to the second state in the above-mentioned embodiment.

Furthermore, the operational amplifier OPRA is used as an emitter follower to isolate the dynamic switching of the reference electrode and the input signal of the RLD circuit to avoid mutual interference. It should choose a precision operational amplifier with an input offset voltage of no more than 10V, so as not to produce obvious errors when following the surface electromyographic signal with a weak amplitude.

Among them, the RLD circuit is composed of an inverse proportional operation circuit composed of an operational amplifier OPRC, a resistor Rf, and a capacitor Cf, and an emitter follower composed of an operational amplifier OPRB. Through the negative feedback amplification of the common-mode voltage of the input signals of all measurement channels, a closed-loop feedback compensation system can be established to effectively suppress common-mode interference. When using the reference electrode dynamic switching circuit to switch the reference, the different opening and closing methods of the switches SxP, SxN, SR1, and SR2 ensure that the common-mode reference point Uc is always the common-mode voltage of all input signals. VRLDREF is used to provide the DC reference voltage to the output of the inverse proportional operation circuit and the human body, which is usually taken as half of the ADC power supply voltage. In order to establish an effective negative feedback path, the resistance value of the feedback resistor Rf should be more than 10 times that of the input resistor R3. The emitter follower is used to isolate the dynamic switching of the reference electrode and the input signal of the RLD circuit to avoid mutual interference. The OPRB should use a precision operational amplifier with an input offset voltage not exceeding 10V.

Among them, the ADC circuit is used to convert the amplified surface electromyographic analog signal output by the PGA into a digital signal, and send it to a microcontroller, DSP and other microprocessors through a communication interface for further processing such as subsequent storage and analysis.

When used in conjunction with existing multi-channel EMG acquisition equipment, please refer to FIG. 3 , which is a structural schematic diagram of another embodiment of a dynamic switching device for EMG acquisition reference electrodes provided by the present application. Taking the ADS1298 multi-channel EMG acquisition front-end chip commonly used in existing multi-channel EMG acquisition equipment as an example, other EMG acquisition chips are similar to its principle framework, and this embodiment can also be referred to.

The ADS1298 chip integrates modules such as multiplexer, PGA and ADC (some modules and pins are not shown), and each PGA positive and negative polarity output terminal can be collected to the RLDINV pin by a 220kΩ current limiting resistor, and through Programmable analog switches RLDxP, RLDxN (x=1,2,...,n) to control. It can be seen that RLDxP, RLDxN, and 220kΩ current-limiting resistors can replace SxP, SxN, and R3 in Figure 2 to play the same role, and the RLDINV pin is the common-mode reference point Uc. In order to realize the dynamic switching function of the reference electrode in the embodiment of the present application, only the operational amplifier OPRA in FIG. 2 , the programmable analog switches SR1 and SR2 and the RLD circuit need to be added, which is very convenient. When collecting surface electromyographic signals, if you need to switch the reference electrode to an external reference, you can close the RLDxP and RLDxN of the channel in use, and at the same time close SR1 and disconnect SR2; if you need to switch the reference electrode to the average reference, you can disconnect Put the SxN of the channel into use, close SR2 and open SR1 at the same time.

The following continues to describe the potential signal change of the dynamic switching device in Figure 2 combined with the dynamic switching of the reference electrode:

When using the dynamic switching device of the electromyography acquisition reference electrode of the embodiment of the present application to acquire sEMG signals, first, according to whether the measurement electrode is a discrete patch electrode or an array electrode, an external reference or an average reference is selected as the reference electrode correspondingly, wherein, if the measurement electrode If it is a discrete patch electrode, you should choose an external reference electrode; if the measurement electrode is an array electrode, you should choose an average reference electrode.

For example, if the measurement electrodes use discrete patch electrodes, you can close the SxP and SxN (x=1,2,…,n) of the active channel, close SR1 at the same time, open SR2, and switch the reference electrode to an external reference. At this time, the potential of the negative input terminal of the PGA circuit is:

UixN=UR

Among them, the operational amplifiers OPxA and OPxB of the PGA circuit are in the state of negative feedback linear amplification, and it can be obtained:

Right now:

The above formula gives the gain of PGA, which can be adjusted by R2. Therefore, further, the potentials of the positive output terminal and the negative output terminal of the PGA can be obtained as follows:

It can be obtained that the voltage of the common-mode reference point Uc is:

It can be seen from the above formula that the common-mode reference point Uc is the common-mode voltage of the input signals of all measurement channels. After introducing it into the RLD circuit, it is fed back to the human body through the driving electrode of the right leg, which can effectively suppress the common-mode interference.

Further, when the reference electrode uses an external reference electrode, it is detected whether the electrode is off by measuring the electrode impedance, etc. If the measurement electrode is found to be off, the myoelectric collection data of the electrode off channel should be ignored, and the switches SxP and SxN of the off channel should be turned off at the same time. .

During the acquisition process, real-time monitor the EMG acquisition data of the normally used channel, if the data of a certain channel exceeds the range of the channel and lasts for a long time (such as greater than 10 seconds). After excluding external electromagnetic interference factors, it can be considered that the reason is that the contact impedance between the external reference electrode and the measuring electrode and the skin changes greatly, resulting in excessive zero point drift of the EMG signal and exceeding the range of the ADC.

At this time, in order to ensure the correct collection of surface electromyographic data and the smooth progress of the test, the external reference electrode can be switched to the average reference electrode, that is, the SxN of the channel that is put into use is disconnected, and SR2 is closed at the same time, SR1 is disconnected, and the positive polarity of the PGA The output terminal UoxP is connected to the negative polarity input terminal UixN through the common mode reference point Uc. At this time, the potential of the negative input terminal of the PGA circuit is:

UixN=Uc

Among them, the operational amplifiers OPxA and OPxB of the PGA circuit are still in the state of negative feedback linear amplification, which can be obtained:

Therefore, the PGA can still effectively amplify the differential mode component of the input signal, and the gain is the same as when using an external reference electrode. At this time, the potential of the PGA positive polarity output terminal is:

Further, adding the potentials of all PGA positive polarity output terminals can obtain the voltage of the common mode reference point Uc as:

Right now:

Therefore, although the PGA amplifies the differential mode component of the input signal of the measurement channel, a negative feedback loop is formed by connecting the positive output terminal of the PGA to the negative input terminal, so that the voltage of the common mode reference point Uc remains equal to the entire input signal common-mode voltage, rather than the average value amplified by the PGA. Therefore, it can also be introduced into the RLD loop for suppression of common-mode interference.

Further, when the average reference electrode is used as the reference electrode, it is detected whether the electrode is off by measuring the electrode impedance, etc. If the measurement electrode is found to be off, the myoelectric collection data of the electrode off channel should be ignored, and the switches SxP and SxN of the off channel should be turned off at the same time. .

During the collection process, the number and distribution of the normally used measuring electrodes are monitored in real time. If the number is too small (for example, less than 8), the distribution is obviously uneven. Switch the average reference to the external reference, that is, close the SxP and SxN of the channel in use, close SR1 at the same time, and open SR2.

The dynamic switching device of the embodiment of the present application can make the existing multi-channel myoelectric acquisition equipment better adapt to measurement electrodes of different properties such as discrete patch electrodes and array electrodes by dynamically switching the external reference and average reference electrodes from the hardware. , to avoid the failure to collect surface electromyography signals due to excessive electrode measurement impedance drift, or the loss of useful information of surface electromyography signals due to the small number of measuring electrodes and uneven distribution. Improve the accuracy, data integrity and efficiency of surface electromyography signal acquisition; in addition, by cleverly introducing negative feedback into the programmable gain amplifier circuit, the sampling point of the average reference voltage is set after the programmable gain amplifier circuit, and the right The voltage sampling points of the leg drive circuit are the same, rather than before the programmable gain amplifier circuit in the prior art, which makes the dynamic switching device of the embodiment of the present application easily integrated into the existing myoelectric collection device or chip, The use is flexible and convenient, and the use cost is reduced.

Please continue to refer to FIG. 4 . FIG. 4 is a schematic flowchart of an embodiment of a method for dynamically switching reference electrodes for EMG collection provided by the present application.

Specifically, as shown in FIG. 4, the dynamic switching method in the embodiment of the present application specifically includes the following steps:

Step S11: Using discrete patch electrodes to collect surface electromyographic signals, wherein the reference electrode is an external reference electrode.

Among them, the dynamic switching device of the EMG acquisition reference electrode is used to collect sEMG signals, and when the measurement electrode is a discrete patch electrode, an external reference electrode is selected as the reference electrode.

Step S12: judging whether the amplitude of the surface electromyography signal reaches the preset range of the channel.

Wherein, during the collection process, the dynamic switching device needs to judge whether the amplitude of the collected surface electromyography signal is greater than the preset range of the channel, and if so, proceed to step S13.

Specifically, during the acquisition process, the EMG acquisition data of the channels normally used are monitored in real time, if the data of a certain channel exceeds the range of the channel and lasts for a long time (for example, greater than 10 seconds). After excluding external electromagnetic interference factors, it can be considered that the reason is that the contact impedance between the external reference electrode and the measuring electrode and the skin changes greatly, resulting in excessive zero point drift of the EMG signal and exceeding the range of the ADC. At this time, in order to ensure the correct collection of surface electromyography data and the smooth progress of the test, the external reference electrode can be switched to the average reference electrode, that is, step S13 is entered.

Step S13: Switch the reference electrode to an average reference electrode through a dynamic switching device.

Wherein, for the specific structure and switching logic of the dynamic switching device in the embodiment of the present application, please refer to the dynamic switching device in Fig. 1 to Fig. 3 , which will not be repeated here.

Further, when the embodiment of the present application uses an external reference electrode as the reference electrode, it is also possible to detect whether the electrode has fallen off by measuring the electrode impedance. Switches SxP, SxN of the drop channel.

Please continue to refer to FIG. 5 . FIG. 5 is a schematic flowchart of another embodiment of the method for dynamically switching reference electrodes for EMG collection provided by the present application.

Specifically, as shown in FIG. 5, the dynamic switching method in the embodiment of the present application specifically includes the following steps:

Step S21: using the array patch electrodes to collect surface electromyographic signals, wherein the reference electrode is an average reference electrode.

Wherein, the dynamic switching device of the electromyography acquisition reference electrode is used to acquire the sEMG signal, and when the measurement electrode is an array electrode, the corresponding average reference electrode is selected as the reference electrode.

Step S22: judging whether the number of measuring electrodes corresponding to the surface electromyography signal is less than a preset number.

Among them, during the acquisition process, the dynamic switching device needs to monitor the number and distribution of the normally used measuring electrodes in real time, so as to judge whether the number of measuring electrodes corresponding to the surface electromyography signal is less than the preset number, or whether the measuring electrodes corresponding to the surface electromyography signal Is the distribution significantly uneven. Wherein, the preset number can be set to 8 or other numerical values. If yes, go to step S23.

Step S23: Switch the reference electrode to an external reference electrode through a dynamic switching device.

Wherein, for the specific structure and switching logic of the dynamic switching device in the embodiment of the present application, please refer to the dynamic switching device in FIGS. 1-3 , which will not be repeated here.

Further, when the average reference electrode is used as the reference electrode in the embodiment of the present application, it is also possible to detect whether the electrode has fallen off by measuring the electrode impedance. Switches SxP, SxN of the drop channel.

Those skilled in the art can understand that in the above method of specific implementation, the writing order of each step does not mean a strict execution order and constitutes any limitation on the implementation process. The specific execution order of each step should be based on its function and possible The inner logic is OK.

In order to realize the dynamic switching method of the EMG acquisition reference electrode in the above embodiment, the present application also proposes a terminal device, please refer to FIG. 6 for details. FIG. 6 is a schematic structural diagram of another embodiment of the terminal device provided in the present application.

The terminal device 600 in this embodiment of the present application includes a memory 61 and a processor 62, where the memory 61 and the processor 62 are coupled.

The memory 61 is used to store program data, and the processor 62 is used to execute the program data to realize the dynamic switching method of the reference electrode for myoelectric collection described in the above-mentioned embodiment.

In this embodiment, the processor 62 may also be referred to as a CPU (Central Processing Unit, central processing unit). The processor 62 may be an integrated circuit chip with signal processing capabilities. The processor 62 can also be a general processor, a digital signal processor (DSP, Digital Signal Process), an application specific integrated circuit (ASIC, Application Specific Integrated Circuit), a field programmable gate array (FPGA, Field Programmable Gate Array) or other possible Program logic devices, discrete gate or transistor logic devices, discrete hardware components. A general purpose processor can be a microprocessor or the processor 62 can be any conventional processor or the like.

The present application also provides a computer storage medium. As shown in FIG. 7, the computer storage medium 700 is used to store program data 71. When the program data 71 is executed by the processor, it is used to realize the myoelectric collection as described in the above-mentioned embodiments. Dynamic switching method of reference electrode.

The present application also provides a computer program product, wherein the above-mentioned computer program product includes a computer program, and the above-mentioned computer program is operable to make the computer execute the method for dynamically switching the reference electrode for electromyography collection as described in the embodiment of the present application. The computer program product may be a software installation package.

The dynamic switching method of the myoelectric acquisition reference electrode described in the above-mentioned embodiments of the present application exists in the form of a software function unit and when it is sold or used as an independent product, it can be stored in the device, such as a computer-readable in the storage medium. Based on this understanding, the technical solution of the present application is essentially or part of the contribution to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , including several instructions to make a computer device (which may be a personal computer, server, or network device, etc.) or a processor (processor) execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disc, etc., which can store program codes. .

The above is only the implementation of the application, and does not limit the patent scope of the application. Any equivalent structure or equivalent process conversion made by using the specification and drawings of the application, or directly or indirectly used in other related technologies fields, are all included in the scope of patent protection of this application in the same way.

Claims

A kind of dynamic switching device of myoelectric acquisition reference electrode, it is characterized in that, described dynamic switching device comprises:

Measuring electrodes for several channels;

A programmable gain amplifier circuit of several channels, the positive input end of the programmable gain amplifier circuit is connected to the output end of the measurement electrode;

An external reference electrode is connected to the programmable gain amplifier circuit through a reference electrode dynamic switching circuit;

Wherein, when the reference electrode dynamic switching circuit is in the first state, the external reference electrode is connected to the negative input terminals of all the programmable gain amplifier circuits, so as to switch the reference electrode for myoelectric collection to the external reference electrode; When the reference electrode dynamic switching circuit is in the second state, the positive output terminals of all the programmable gain amplifier circuits are connected to the negative input terminals of the programmable gain amplifier circuits after being sampled by the voltage mean value to form a negative feedback loop to convert the myoelectric The acquired reference electrode is switched to the averaging reference electrode.
The dynamic switching device according to claim 1, characterized in that,

The reference electrode dynamic switching circuit includes a first channel switch of several channels, a second channel switch of several channels, a first switching switch and a second switching switch.
The dynamic switching device according to claim 2, characterized in that,

When the reference electrode dynamic switching circuit is in the first state, the first channel switch, the second channel switch and the first switching switch of the several channels are closed, and the second switching switch is open, so that the programmable The negative input terminal of the gain amplifier circuit is connected to the external reference electrode.
The dynamic switching device according to claim 2, characterized in that,

When the reference electrode dynamic switching circuit is in the second state, the first channel switches and the second switch of the several channels are closed, the second channel switches of the several channels and the first switch are opened, The positive output ends of all the programmable gain amplifying circuits are connected to the negative input ends of the programmable gain amplifying circuits after being sampled by the average voltage, forming a negative feedback loop.
The dynamic switching device according to claim 2, characterized in that,

The reference electrode dynamic switching circuit also includes current limiting resistors of several channels, the first channel switch, the second channel switch and the current limiting resistors of several channels form a voltage mean value sampling circuit, and the voltage mean value sampling circuit is used to select the The positive output terminal and the negative output terminal of the programmable gain amplifier circuit are connected to the common mode reference point to obtain the average voltage of all gating signals.
The dynamic switching device according to claim 2, characterized in that,

When the reference electrode dynamic switching circuit is in the third state, the first channel switch and the second channel switch of the target channel are turned off, so as to turn off the measurement electrode corresponding to the target channel.
A kind of dynamic switching method of myoelectric acquisition reference electrode, it is characterized in that, described dynamic switching method comprises:

Use discrete patch electrodes to collect surface electromyographic signals, where the reference electrode is an external reference electrode;

judging whether the amplitude of the surface electromyographic signal reaches the preset range of the channel;

If so, switching the reference electrode to an average reference electrode through a dynamic switching device;

Wherein, the dynamic switching device is the dynamic switching device according to any one of claims 1-6.
The dynamic switching method according to claim 7, wherein the dynamic switching method further comprises:

Obtain the impedance of the measuring electrode based on the surface electromyographic signal of each channel;

judging whether the impedance of the measuring electrode is greater than a preset impedance value;

If yes, ignore the surface electromyographic signal of the channel measuring electrode.
A kind of dynamic switching method of myoelectric acquisition reference electrode, it is characterized in that, described dynamic switching method comprises:

Use array patch electrodes to collect surface electromyographic signals, where the reference electrode is an average reference electrode;

judging whether the number of measuring electrodes corresponding to the surface electromyographic signal is less than a preset number;

If so, switching the reference electrode to an external reference electrode through a dynamic switching device;

Wherein, the dynamic switching device is the dynamic switching device according to any one of claims 1-6.
The dynamic switching method according to claim 9, wherein the dynamic switching method further comprises:

Obtain the impedance of the measuring electrode based on the surface electromyographic signal of each channel;

judging whether the impedance of the measuring electrode is greater than a preset impedance value;

If yes, ignore the surface electromyographic signal of the channel measuring electrode.