Electrical stimulation system, electrical stimulation control device, control device operation method and program

Abstract

One aspect of this invention uses an electrical stimulation control device to: acquire biological information in which muscle contraction of a target portion from a sensor part is reflected; estimate, on the basis of the biological information, voluntary contraction strength of a muscle in the target portion; determine whether the estimated voluntary contraction strength has reached a range of strength indicating a preliminarily set maximum voluntary contraction; and carry out control such that application of an electrical stimulation signal from an electrical stimulation generation unit to the target portion is stopped when the voluntary contraction strength has reached the range of strength indicating the maximum voluntary contraction.

Description

[Technical Field]

[0001] One aspect of the present invention is, for example, an electrical stimulation system that supports human muscle movement using electrical stimulation, and an electrical stimulation control device included in the system. Control device operation method and regarding the program. [Background technology]

[0002] Systems have been proposed that use electrical muscle stimulation (EMS), a technology that applies electrical stimulation to muscles to induce involuntary contractions. For example, Non-Patent Document 1 describes a technology that applies electrical stimulation to the forearm muscles of stroke patients to assist them in exerting their grip strength. This technology measures the myoelectric potential of the forearm and applies electrical stimulation when a certain amplitude or greater is detected.

[0003] However, recent research has shown that applying electrical stimulation to muscles that exert grip strength when they are undergoing sufficiently large voluntary contractions actually reduces grip strength. This research is described, for example, in Non-Patent Document 2. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Zeng, Jia, et al. "Hand grip force enhancer based on sEMG-triggered functional electrical stimulation." 2019 IEEE 9th Annual International Conference on CYBER Technology in Automation, Control, and Intelligent Systems (CYBER). IEEE, 2019. [Non-patent document 2] Boisgontier, Matthieu, Nicolas Vuillerme, and Maura Iversen. "Superimposed electrical stimulation decreases maximal grip force." Journal of sports medicine and physical fitness 50.2 (2010): 152-8. Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, when applying electrical stimulation to muscles to support their movement, depending on how the electrical stimulation is applied, it may actually inhibit the muscle movement. For this reason, there is a need for a more effective method of controlling electrical stimulation.

[0006] The present invention has been made in light of the above circumstances, and aims to provide a technique that makes it possible to more effectively support muscle movement. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the electrical stimulation system according to the present invention includes an electrical stimulation generator that generates an electrical stimulation signal and applies the generated electrical stimulation signal to a target area, a sensor that detects biological information reflecting muscle contraction in the target area, and an electrical stimulation control device connected to the electrical stimulation generator and the sensor. The electrical stimulation control device acquires the biological information detected by the sensor and estimates a voluntary contraction strength of the muscle in the target area based on the biological information, determines whether the estimated voluntary contraction strength reaches a predetermined range of strength representing a maximum voluntary contraction, and controls the electrical stimulation generator to stop applying the electrical stimulation signal to the target area when the voluntary contraction strength reaches the range of strength representing the maximum voluntary contraction.

[0008] According to one aspect of the present invention, the application of electrical stimulation is stopped when the estimated value of voluntary contraction strength reaches the range of the strength of maximum voluntary contraction, allowing a person to exert their maximum inherent grip strength compared to when electrical stimulation is continuously applied to the muscles of the target area. [Effects of the Invention]

[0009] That is, according to one aspect of the present invention, it is possible to provide a technique that enables muscle movement to be more effectively supported. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an electrical stimulation system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of a hardware configuration of an electrostimulation control device included in the electrostimulation system shown in FIG. [Figure 3] FIG. 3 is a block diagram showing an example of a software configuration of an electrostimulation control device included in the electrostimulation system shown in FIG. [Figure 4] FIG. 4 is a flowchart illustrating an example of a procedure and content of an electrostimulation control process executed by the control unit of the electrostimulation control device shown in FIG. [Figure 5] FIG. 5 shows an example of the measurement results of the intensity of gripping force generated depending on whether or not electrical stimulation is applied and the location where it is applied. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] [One embodiment] (Configuration example) (1) System In one embodiment of the present invention, an example will be described in which electrical stimulation is applied to muscles that exert a person's grip strength.

[0013] 1 is a diagram showing an example of the configuration of an electrical stimulation system according to an embodiment of the present invention. The electrical stimulation system EM according to the embodiment includes an electrical stimulation control device 1, an electrical stimulation generator 2, an electromyography sensor 3, and an operation device 4.

[0014] The electrical stimulation generator 2 generates an electrical stimulation signal that electrically stimulates the target area of ​​a person, in this example, the muscles of the forearm HD. For example, by superimposing a stimulation frequency of 15 to 200 Hz on a reference frequency of several kHz to 20 kHz, it generates a low-frequency stimulation signal suitable for simulated muscle contraction. The electrical stimulation generator 2 supplies the generated electrical stimulation signal to an electrical stimulation electrode E1 attached to the skin of the forearm HD. The electrical stimulation electrode E1 is composed of a pair of electrodes E11 and E12, and the electrical stimulation signal is supplied between these electrodes E11 and E12. The reference frequency, stimulation frequency, and signal strength of the electrical stimulation signal can be arbitrarily controlled by a control signal output from the electrical stimulation control device 1 and are set arbitrarily depending on the type and condition of the muscle to be stimulated.

[0015] The electromyography sensor 3 measures the surface electromyography (EMG) of the skin, measuring an electromyographic signal, which is one type of biometric information, using an electrode E2 for measuring myoelectric potential attached to the skin of the forearm HD, and inputs the measured electromyographic signal to the electrical stimulation control device 1. More specifically, the electromyography sensor 3 measures the difference in skin surface potential appearing between two electrodes E21 and E22 that make up electrode E2 as the electromyographic signal. In this example, the amplitude of the electromyographic signal changes depending on the muscle activity of the muscles that exert grip strength.

[0016] Operation device 4 includes, for example, a push button switch that instructs the start and end of electrical stimulation, generates an instruction signal in response to operation of the push button switch, and inputs the generated instruction signal to electrical stimulation control device 1. Note that operation device 4 may also be a keyboard or mouse attached to a personal computer, or a touch panel included in a smartphone, or the like.

[0017] (2) Electrical stimulation control device 1 The electrical stimulation control device 1 may be, for example, a device dedicated to rehabilitation, and may be placed on a table or attached to the patient's body. Note that the electrical stimulation control device 1 may also be provided as part of the functionality of, for example, a smartphone, tablet terminal, or personal computer.

[0018] 2 and 3 are block diagrams showing an example of a hardware configuration and a software configuration, respectively, of the electrical stimulation control device 1. As shown in FIG.

[0019] The electrical stimulation control device 1 includes a control unit 10 that uses a hardware processor such as a central processing unit (CPU), and a memory unit having a program memory unit 20 and a data memory unit 30, and an input / output interface (hereinafter, interface will be abbreviated as I / F) unit 40 are connected to the control unit 10 via a bus 50.

[0020] The input / output I / F unit 40 outputs a control signal to the electrical stimulation generator 2, and inputs an electromyographic signal output from the electromyographic sensor 3 and an instruction signal output from the operation device 4. The input / output I / F unit 40 may also have a communication interface function. By providing the communication interface function, signals can be transmitted and received between the electrical stimulation generator 2, the electromyographic sensor 3, and the operation device 4 using a low-power wireless communication interface such as Bluetooth (registered trademark), thereby reducing the burden on the patient's movements.

[0021] The program storage unit 20 is configured by combining, for example, a nonvolatile memory such as a solid state drive (SSD) as a storage medium that can be written to and read from at any time, and a nonvolatile memory such as a read-only memory (ROM), and stores middleware such as an operating system (OS), as well as application programs required to execute various controls according to an embodiment. Hereinafter, the OS and each application program will be collectively referred to as the program.

[0022] The data storage unit 30 is, for example, a combination of a non-volatile memory such as an SSD that can be written to and read from at any time as a storage medium, and a volatile memory such as a RAM (Random Access Memory), and the storage area thereof is provided with an electromyographic signal storage unit 31 and a threshold storage unit 32 as the main storage units required to implement one embodiment.

[0023] The myoelectric signal storage unit 31 temporarily stores the myoelectric signal output from the myoelectric sensor 3 for the voluntary contraction intensity estimation process described later. The threshold value storage unit 32 saves a threshold value used to determine the magnitude of the voluntary contraction intensity estimated by the voluntary contraction intensity estimation processing unit described later.

[0024] The control unit 10 includes, as processing functions necessary for carrying out one embodiment, a myoelectric signal acquisition processing unit 11, a voluntary contraction intensity estimation processing unit 12, an intensity determination processing unit 13, and an electrical stimulation generation control processing unit 14. These processing units 11 to 14 are all realized by causing a hardware processor of the control unit 10 to execute application programs stored in a program storage unit 20.

[0025] Note that part or all of the processing units 11 to 14 may be realized using hardware such as an LSI (Large Scale Integration) or an ASIC (Application Specific Integrated Circuit).

[0026] The myoelectric signal acquisition processing unit 11 acquires the myoelectric signal output from the myoelectric sensor 3 via the input / output I / F unit 40. Then, the acquired myoelectric signal is stored in the myoelectric signal storage unit 31.

[0027] The voluntary contraction strength estimation processing unit 12 reads, for example, a certain period of myoelectric signals from the myoelectric signal storage unit 31. Then, it detects the amplitude value of the read myoelectric signals and estimates the voluntary contraction strength of the muscle based on the magnitude of the detected amplitude value.

[0028] The intensity determination processing unit 13 compares the voluntary contraction intensity estimated by the voluntary contraction intensity estimation processing unit 12 with the threshold value stored in the threshold memory unit 32 to determine whether the voluntary contraction intensity has reached the range of intensity corresponding to the maximum voluntary contraction, and provides the determination result to the electrical stimulation generation control processing unit 14.

[0029] The electrical stimulation generation control processing unit 14 controls the start and end of electrical stimulation in response to an instruction signal input from the operation device 4. At the same time, the electrical stimulation generation control processing unit 14 controls whether to continue or stop the electrical stimulation in response to the determination result of the voluntary contraction intensity.

[0030] (Example of operation) Next, the operation of the electrical stimulation system EM configured as above will be described in accordance with the control procedure of the electrical stimulation control device 1.

[0031] FIG. 4 is a flowchart showing an example of the procedure and content of the control process executed by control unit 10 of electrostimulation control device 1.

[0032] (1) Start of electrical stimulation When the electrical stimulation start button on the operation device 4 is operated, an electrical stimulation start instruction signal is output from the operation device 4, and this electrical stimulation start instruction signal is input to the electrical stimulation control device 1. When the control unit 10 of the electrical stimulation control device 1 recognizes the input of the electrical stimulation start instruction signal in step S10, it generates an electrical stimulation generation control signal in step S11 under the control of the electrical stimulation generation control processing unit 14, and outputs the generated electrical stimulation generation control signal from the input / output I / F unit 40 to the electrical stimulation generator 2.

[0033] When the electrical stimulation generation control signal is output, the electrical stimulation generator 2 generates an electrical stimulation signal and supplies the generated electrical stimulation signal to the forearm HD via the electrode E1. As a result, the muscles of the forearm HD receive the electrical stimulation and contract, and as if attracted by this electrical stimulation, the person moves the muscles of their own volition to exert grip strength. In other words, a voluntary contraction movement occurs.

[0034] (2) Measurement of electromyographic signals When the muscles of the forearm HD voluntarily contract as a result of exerting the grip force, a biopotential signal corresponding to the strength of the contraction is detected by the electromyography sensor 3, and this detected biopotential signal is input to the electrical stimulation control device 1.

[0035] In step S12, the control unit 10 of the electrical stimulation control device 1, under the control of the myoelectric signal acquisition processing unit 11, acquires the above-mentioned myoelectric signal via the input / output I / F unit 40 and stores the acquired myoelectric signal in the myoelectric signal memory unit 31.

[0036] (3) Estimation and evaluation of voluntary contraction strength When the application of the electrical stimulation is started, in step S13, control unit 10 of electrical stimulation control device 1 then reads myoelectric signals from myoelectric signal storage unit 31, for example, for a fixed period at a time, and calculates, for example, the average value of the amplitude values ​​of the myoelectric signals for each of the read fixed periods, under the control of voluntary contraction intensity estimation processing unit 12. In this case, voluntary contraction intensity estimation processing unit 12 may calculate other values, such as a maximum value, in addition to calculating the average value.

[0037] Then, the voluntary contraction strength estimation processing unit 12 estimates the voluntary contraction strength of the muscles involved in exerting the grip strength based on the magnitude of the calculated amplitude value of the myoelectric signal. This estimation of the voluntary contraction strength is performed, for example, by multiplying the calculated value of the amplitude value of the myoelectric signal by a predetermined conversion coefficient.

[0038] Incidentally, the electromyographic signal is contaminated with an electrical stimulation signal as an interference component. For this reason, the control unit 10 of the electromyographic control device 1 generates the electrical stimulation signal, for example, intermittently, under the control of the electrical stimulation generation control processing unit 14. Then, the amplitude value of the electromyographic signal detected during the period when the electrical stimulation signal is not generated is used to estimate the strength of the voluntary contraction.

[0039] Next, in step S14, under the control of intensity determination processing unit 13, control unit 10 of electrical stimulation control device 1 compares the estimated value of voluntary contraction intensity with a threshold value stored in threshold memory unit 32 to determine whether the estimated value of voluntary contraction intensity is equal to or greater than the threshold value. At this time, the threshold value is set to the lower limit of the range of intensity corresponding to maximum voluntary contraction. Therefore, in step S14, it is determined whether the estimated value of voluntary contraction intensity has reached the range of intensity corresponding to maximum voluntary contraction. Intensity determination processing unit 13 notifies electrical stimulation generation control processing unit 14 of the determination result.

[0040] (4) Control after electrical stimulation Control unit 10 of electrostimulation control device 1, under the control of electrostimulation generation control processing unit 14, controls whether to continue or stop applying electrostimulation in accordance with the determination result of intensity determination processing unit 13.

[0041] That is, when the electrical stimulation generation control processing unit 14 determines that the estimated value of the voluntary contraction intensity has reached the range of intensity corresponding to the maximum voluntary contraction, in step S16, it generates an electrical stimulation stop signal and outputs the generated electrical stimulation stop signal from the input / output I / F unit 40 to the electrical stimulation generator 2. As a result, the electrical stimulation generator 2 stops generating the electrical stimulation signal, thereby stopping the application of electrical stimulation to the forearm HD. Therefore, the muscles of the forearm HD can thereafter perform voluntary contraction without being affected by the electrical stimulation, thereby maintaining the maximum voluntary contraction.

[0042] Figure 5 shows an example of the results of an experiment to confirm the effect of applying electrical stimulation on grip strength. The results of this experiment were conducted on 20 healthy subjects, and they were asked to exert maximum grip strength without applying electrical stimulation (EMS) (no-EMS), while applying EMS of about 10 mA to the muscles of the forearm (EMS to forearm), and while applying EMS of about 10 mA to the muscles of the shoulder (EMS to shoulder). The maximum grip strength of each subject was measured in each case and displayed using a box-and-whisker plot.

[0043] According to the results of this experiment, the average grip strength in each of the above cases was 33.4 kgw (no-EMS), 30.9 kgw (EMS to forearm), and 32.4 kgw (EMS to shoulder). In other words, it was confirmed that when EMS is applied to the forearm or shoulder, maximum grip strength decreases compared to when EMS application is stopped.

[0044] Therefore, as in one embodiment, by stopping the application of electrical stimulation when the maximum voluntary contraction is exerted, the person can exert their natural maximum grip strength.

[0045] If it is determined that the estimated value of the voluntary contraction intensity does not reach the range of intensity corresponding to the maximum voluntary contraction, the electrical stimulation generation control processor 14 continues to generate electrical stimulation signals from the electrical stimulation generator 2. As a result, electrical stimulation continues to be applied to the muscles of the forearm HD.

[0046] Then, control unit 10 of electrical stimulation control device 1 returns from step S14 to step S12, and continues the series of electrical stimulation generation controls based on the voluntary contraction intensity described above in (2) to (4).

[0047] (5) Termination of electrical stimulation When the electrical stimulation end button on the operating device 4 is operated and an electrical stimulation end instruction signal is input to the electrical stimulation control device 1, the control unit 10 of the electrical stimulation control device 1 detects the input of the electrical stimulation end instruction in step S15. Then, under the control of the electrical stimulation generation control processing unit 14, the control unit 10 of the electrical stimulation control device 1 ends the application of electrical stimulation to the muscles of the forearm HD by the electrical stimulation generator 2 in step S16.

[0048] (Actions and Effects) As described above, in one embodiment, the electrical stimulation control device 1 applies electrical stimulation to a muscle in the forearm HD, which is a target area, acquires an electromyographic signal corresponding to the activity of the muscle, and estimates the voluntary contraction strength of the muscle based on the amplitude of the electromyographic signal. The estimated value of voluntary contraction strength is then compared with a preset threshold value to determine whether the estimated value of voluntary contraction strength has reached the range of the maximum voluntary contraction strength. If it is determined that the estimated value has reached the range, the application of electrical stimulation is stopped at that point.

[0049] Therefore, according to one embodiment, compared to when electrical stimulation is continuously applied, a person can exert their inherent maximum grip strength. Also, in one embodiment, electrical stimulation is applied intermittently, and the voluntary contraction strength is estimated from the EMG signal detected during the period when electrical stimulation is not applied. Therefore, the voluntary contraction strength can be estimated based on the EMG signal that does not contain interference components due to the electrical stimulation signal, thereby enabling highly accurate determination.

[0050] [Other embodiments] (1) In one embodiment, the voluntary contraction strength is estimated based on the amplitude of an electromyographic signal. However, the present invention is not limited to the above example. For example, low-frequency vibrations generated by muscles may be detected as muscle sounds using a microphone, and the voluntary contraction strength may be estimated based on the amplitude of the detected muscle sounds. Alternatively, an ultrasound echo image of a muscle site may be captured using a camera, and the voluntary contraction strength of the muscle may be estimated based on the obtained ultrasound echo image. Estimating the voluntary contraction strength using muscle sounds and ultrasound echoes in this way makes it possible to estimate the voluntary contraction strength without interference from current noise in electrical stimulation.

[0051] (2) In the embodiment, the electrical stimulation control device 1, the electrical stimulation generator 2, and the myoelectric sensor 3 are provided as separate, independent devices. However, at least one of the electrical stimulation generator 2 and the myoelectric sensor 3 may be configured to be built into the electrical stimulation control device 1 as one of its functions.

[0052] (3) In one embodiment, the case of assisting a patient in exerting their grip strength has been described as an example, but the present invention can also be applied to assisting muscle activity in other parts of the patient. Furthermore, the present invention may also be applied to healthy individuals other than patients depending on the purpose. In addition, the functional configuration, processing procedures and processing contents of the electrical stimulation control device, the method of generating an electrical stimulation signal by the electrical stimulation generator, the method of estimating voluntary contraction strength, etc. can be modified and implemented in various ways without departing from the spirit of this invention.

[0053] Although the embodiments of the present invention have been described in detail above, the above description is merely an example of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In other words, when implementing the present invention, specific configurations according to the embodiments may be appropriately adopted.

[0054] In short, this invention is not limited to the above-described embodiments, and in the implementation stage, the components can be modified and embodied without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0055] EM...electrical stimulation system E1,E2…electrode 1...Electrical stimulation control device 2...Electrical stimulation generator 3...Electromyography sensor 4. Control device 10...Control unit 20...Program memory section 30...Data storage unit 40...Input / output interface 50...Bus 11...Electromyographic signal acquisition processing unit 12...Voluntary contraction strength estimation processing unit 13...Intensity determination processing unit 14...Electrical stimulation generation control processing unit 31...Electromyographic signal storage unit 32...Threshold value memory section

Claims

1. an electrical stimulation generating unit that generates an electrical stimulation signal and applies the generated electrical stimulation signal to a target site; a sensor unit that detects biological information that reflects muscle contraction in the target area; an electrical stimulation control device connected to the electrical stimulation generation unit and the sensor unit; Equipped with The electrical stimulation control device includes: a first processing unit that acquires the biological information detected by the sensor unit and estimates a voluntary contraction strength of the muscle of the target region based on the acquired biological information; a second processing unit that determines whether the estimated voluntary contraction strength reaches a predetermined range of strength representing a maximum voluntary contraction; a third processing unit that stops the application of the electrical stimulation signal to the target area by the electrical stimulation generation unit when the voluntary contraction intensity reaches a range of intensity representing the maximum voluntary contraction; An electrical stimulation system comprising:

2. the sensor unit detects, as the biological information, a myoelectric signal that reflects muscle activity of the target part; the first processing unit of the electrical stimulation control device acquires the myoelectric signal and estimates the voluntary contraction intensity of the muscle of the target site based on the magnitude of an amplitude value of the acquired myoelectric signal. The electrical stimulation system of claim 1 .

3. the electrical stimulation generation unit intermittently applies the electrical stimulation signal to the target site; the first processing unit of the electrical stimulation control device acquires the myoelectric signals and estimates the voluntary contraction intensity of the muscle of the target site based on the magnitude of an amplitude value of a signal of the acquired myoelectric signals corresponding to a period during which the electrical stimulation signal is not applied; The electrical stimulation system of claim 2 .

4. An electrical stimulation control device connected to an electrical stimulation generating unit that generates an electrical stimulation signal and applies it to a target site, and a sensor unit that detects biological information reflecting muscle contraction in the target site, a first processing unit that acquires the biological information detected by the sensor unit and estimates a voluntary contraction strength of the muscle of the target region based on the acquired biological information; a second processing unit that determines whether the estimated voluntary contraction strength reaches a predetermined range of strength representing a maximum voluntary contraction; a third processing unit that stops the application of the electrical stimulation signal to the target area by the electrical stimulation generation unit when the voluntary contraction intensity reaches a range of intensity representing the maximum voluntary contraction; An electrical stimulation control device comprising:

5. A method for operating a control device connected to an electrical stimulation generating unit that generates an electrical stimulation signal and applies it to a target area, and a sensor unit that detects biological information reflecting muscle contraction in the target area, the control device operates to acquire the biological information detected by the sensor unit and estimate a voluntary contraction strength of the muscle of the target site based on the acquired biological information; the control device is operative to determine whether the estimated voluntary contraction intensity reaches a preset range of intensity representing a maximum voluntary contraction; The control device operates to stop the application of the electrical stimulation signal to the target area by the electrical stimulation generation unit when the voluntary contraction intensity reaches a range of intensity representing the maximum voluntary contraction. A method of operating a control device comprising:

6. 5. A program causing a processor included in the electrical stimulation control device to execute at least one of the processes performed by the first to third processing units included in the electrical stimulation control device according to claim 4.

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