RU2748428C1 - Complex for bionic control of technical devices - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention relates to medicine, namely to complexes of bionic control of technical devices. The complex contains a biosignal recording unit and a control action implementation unit connected in series to each other, containing a control unit and an executive unit connected in series. The biosignal recording unit includes a current source, two outputs of which are connected respectively to two current electrodes. Two measuring electrodes are connected to the inputs of the input amplifier, the output of which is the input of the units for processing the electromyogram (EMG) and impedance channels, respectively. A mechanomyographic (MMG) channel sensor is introduced into the biosignal registration unit, which is powered by a reference voltage source, the signal from which is fed to an input amplifier, the output of which is connected in series to the input of the MMG processing unit. The outputs of the processing units for the EMG, impedance and introduced MMG channels are connected to the input of the signal registration unit. A modem is introduced into the block for implementing control actions, which is designed to exchange data with modems located in the blocks for registering biosignals.EFFECT: improved control accuracy of technical devices is achieved.1 cl, 6 dwg

Description

The invention relates to biophysics and medical technology and can be used to control technical devices such as a bioelectric prosthesis, bioelectric orthosis, exoskeleton, computer, game console or other technical devices of a similar type.

In recent years, various robotic devices have been increasingly introduced into the field of medicine. This is due to the development of the corresponding element base, the development and creation of biologically safe materials, as well as methods for obtaining and digital processing of information about the state of individual human organs. The most widespread is the use of biopotentials, primarily electromyogram. Electromyography is a method for studying bioelectric potentials arising in the skeletal muscles of humans and animals upon excitation of muscle fibers and recording their electrical activity. It is known that the innervation of electrical impulses of motor units, which form bundles of muscle fibers, leads to depolarization of the membrane of muscle fibers, as a result of which motor units are able to generate an action potential, which propagates along the nerve fibers and causes muscle contraction. Moreover, to maintain muscle contraction, motor units must be innervated repeatedly, which stretches the contraction process over time. The sum of the action potentials from all motor units involved in contraction forms an electromyogram (EMG) signal, which can be recorded using needle or surface electrodes. [De Luca, Carlo (2006), Electromyography. Encyclopedia of Medical Devices and Instrumentation, Second Edition, Volume 3. John Wiley Publisher, pp. 98-109]. Subsequent processing and extraction of informative features from EMG makes it possible to form a control action and implement control of technical devices, for example, bioelectric prostheses. [Alter, Ralph (1966), Bioelectric Control of Prostheses, Technical Report: Massachusetts Institute of Technology, Research Laboratory of Electronics].

The creation of such devices is especially promising for rehabilitation after amputations and paralysis and restoration of the functions of the musculoskeletal system. In such cases, the residual bioelectric activity of the truncated or paralyzed muscles is used to control the movements of the prosthesis or orthopedic apparatus. The electrical activity of the muscles is recorded by electrodes from the stump, the generated electrical signals are received containing data on the type of movement performed. This data is converted into the corresponding control signals of the artificial limb actuators. It is obvious that the creation of high-quality bioelectrical-controlled prostheses requires a high-quality and stable signal from the sensors.

The known method of electromyographic control of prostheses according to the patent WO No. 2012150500, A61F 2/60. A61F 2/68 A61F 2/70), according to which a control signal is formed by registering an electrophysiological signal from a muscle, processing it, transferring the processing results to the control unit and then to the actuator.

The disadvantage of this method, as well as other known methods of electromyographic control of prostheses, is that due to the additive nature of the electromyographic signal, action potentials from neighboring muscles are superimposed on each other, therefore, it is extremely difficult to receive an EMG signal about the activity of a particular muscle. In addition, the influence of cross-talk (interference) from adjacent muscles increases with increasing distance between the measuring electrodes. Another fundamental disadvantage of electromyographic control of prostheses is that EMG signals reflect well only the beginning and end of muscle contraction, but do not give a true idea of the nature of muscle movement during its contraction.

This disadvantage is partially eliminated in the well-known "Method for bionic control of technical devices" presented by patents for invention RU No. 2627818 and WO2017160183, A61B 5/0488, A61F 2/54. The technical problem solved by this invention is to obtain a relatively high-quality and stable signal, which, when controlling the technical device, made it possible to form control actions proportional to the degree of muscle contraction, with a delay of no more than 120 ms. In this case, there is a fundamental possibility of transforming into a control signal "the movement of the muscle itself" in time, while the known methods of removing biopotentials from a muscle using EMG sensors record only the beginning of muscle contraction.

With this method of bionic control of technical devices, the control action is formed by registering an electrophysiological signal from a contracting muscle, processing the signal, transmitting it to the control unit and then to the actuator. In this case, the registration of the electrophysiological signal is carried out by passing an alternating electric current through the muscle, then the electrical impedance is determined, and as a control action, in addition to the EMG signal, a change in the electrical impedance is used during muscle contraction, for the registration of which an electric current is passed through the skin and tissues of a person using current electrodes located on the surface of the skin and / or deep in the tissues. The frequency of the transmitted electric current is preferably selected in the range from 10 kHz to 100 MHz, the amplitude of the current in the range from 0.01 to 10 mA, while the frequency range from 50 Hz to 400 Hz is used to obtain the EMG signal. In this case, the control action is formed using both sensory channels. The complex described in the specified patent for the implementation of this method is selected as a prototype of the present invention.

It allows you to accurately control the movement of the hand prosthesis, providing a distinction between such types of actions performed as flexion and extension, providing the ability to proportionally control the device.

However, the disadvantage of the above prototype is the dependence of the bioimpedance signals on the electrode-skin resistance. Also, it does not allow taking into account the pressing force of the electrode system and its distortions, which significantly affect the quality of recording the bioimpedance signal, which leads to errors in device control. In addition, when the electrode systems are located in the projection of the muscles that are not involved in the performed action, the EMG signal is not expressed, which complicates its analysis.

The present invention is aimed at eliminating these disadvantages, i. E. to control the dependence of the bioimpedance signal on the value of the electrode-skin resistance and the pressing force of the electrode system, to take into account the distortions of the electrode system, to increase the information content of the obtained data by adding an additional informational control channel of the mechanomyogram signal (MMG), as well as to achieve a more accurate and anthropomorphic control of such technical devices such as a bioelectric prosthesis, bioelectric orthosis, exoskeleton, computer, game console, etc.

The expected technical result of the application of the proposed invention is an increase in the efficiency of bionic control of such technical devices.

To achieve this technical result, a third information channel was added to the biosignal registration unit contained in the presented complex for bionic control of technical devices, that is, in the complex of bionic control of technical devices, containing a biosynals registration unit connected in series to each other and a control action implementation unit containing the control unit and the executive unit connected in series, which is the output of the complex, in which the biosignal recording unit includes a current source, two outputs of which are connected respectively to two current electrodes, two measuring electrodes are connected to the inputs of the input amplifier, the output of which is the input of the electromyogram channel processing units (EMG) and impedance, respectively, a mechanomyographic (MMG) channel sensor is introduced into the biosignal recording unit, which is powered from a reference voltage source, the signal from which is fed to the input force tel, the output of which is connected in series to the input of the MMG processing unit, the outputs of the processing units of the EMG, impedance and introduced MMG channels are connected to the input of the signal registration unit, while a modem is inserted into the control action implementation unit capable of exchanging data with the modem located in the unit registration of biosignals.

The invention is illustrated by the following graphic materials.

FIG. 1 Generalized block diagram of the bionic control complex.

FIG. 2 Block diagram of the biosignal registration unit.

FIG. 3 Electrode assembly for registration of biosignals.

FIG. 4 Projections of the forearm muscles involved in relation to the action being performed.

FIG. 5 Example of biosignals during flexion / extension of the hand.

FIG. 6 Example of biosignals when grasping / opening the hand.

The bionic control complex (Fig. 1) of technical devices contains two units connected in series to each other: a biosignal registration unit and a control action implementation unit, which is the output of the complex.

The biosignal registration unit includes a current source (4) connected to two current electrodes (TE1, TE2). The differential signal from two measuring electrodes (IE1, IE2) is fed to the input amplifier (3). The output of the input amplifier (3) is connected to the inputs of the EMG signal processing units (6) and impedance (7), respectively. The third information channel is represented by a force sensor (DS), which is powered by a reference voltage source (1). The signal from the DS is fed to the input amplifier (2), the output of which is connected to the input of the MMG signal processing unit (5). The considered processing units (signals MMG (5), EMG (6) and impedance (7)) are connected to the signal registration unit (8), which can be a common unit for all, or separate for each of the channels.

A modem (11) is introduced into the unit for implementing control actions, which communicates with the modem (9) located in the biosignal registration unit. Thanks to the use of this technology, it is possible to increase the number of channels by combining biosignals registration units and a control action implementation unit into an information network.

The above-described complex of bionic control of technical devices operates as follows (Fig. 2). The microcontroller (5) located in the biosignal recording unit supplies the control voltage to the current source (1), which converts this voltage into a differential alternating electric current with a frequency of 100 kHz and an amplitude of 3 mA. This current is applied to the current electrodes of an electrode assembly located on the surface of the skin over the muscle of interest. The differential voltage across the measuring electrodes, which is recorded by the input amplifier (4), is the sum of the common-mode noise, the EMG signal and the amplitude-modulated voltage at a frequency of 100 kHz, which is the potential difference arising from the action of the current source (1) (electrical impedance signal) ... The main purpose of the input amplifier (4) is to suppress common mode noise. The EMG signal is separated from the electrical impedance signal by a bandpass filter (8) of an EMG channel with a bandwidth from 50 Hz to 500 Hz. The amplitude-modulated electrical impedance signal is separated from the EMG signal by a bandpass filter (9) of the impedance channel with a bandwidth from 10 kHz to 1 MHz and is detected by a synchronous detector (10). To operate the synchronous detector (10) as the carrier of the reference frequency, the microcontroller (5) generates the same reference signal as for the corresponding current source (1). MMG can be registered using DS Honeywell FSG15N1A powered from a reference voltage source (2). The signal from the DS is fed to the input amplifier (3), which removes common-mode noise, then to the MMG channel filter (7) and is additionally amplified using the MMG channel amplifier (11). After additional amplification, signals from all channels (11, 12, 13) are digitized using an analog-to-digital converter (ADC) (14), which can be common for all channels, or separate for each. With the help of the modem (6), the biosignal data is transmitted further to the unit for the implementation of control actions on the control object through the generally accepted transmission interfaces (USB, CAN, Bluetooth, etc.).

Thus, control signals are obtained when using one lead (when registering biosignals from one area). If it is necessary to increase the number of actions recognized by a complex of actions, it is possible to add leads by connecting additional blocks for recording biosignals to the modem of the block for implementing control actions. When registering distortions of the electrode system, two DSs are used.

For the considered complex of bionic control of technical devices, an electrode assembly (Fig. 3) can be used, made on the basis of a tetrapolar retraction system and two force sensors fixed in a mounting platform, in which grooves are provided for fastening medical harnesses, which allows you to reliably fix the electrode assembly for registration signals.

The electrode assembly is located on the forearm, in the projections of the muscles of interest (eg, extensors and flexors of the hand) (Fig. 4). The operator tenses and relaxes the muscles in the same way as with natural hand movements. Signals are recorded from the measuring electrodes and force sensors, as a result of their transformation, control signals are sent to the executive unit, carrying information about the perfect muscle movement.

An example of biosignals within the framework of one study with the location of the electrode assembly in the projection of the extensor muscles when the volunteer performs flexion-extension of the hand, depending on different degrees of pressing of the electrode system, is shown in Fig. five.

An example of biosignals within the framework of one study with the location of the electrode assembly in the projection of the muscles involved in the grip, when the volunteer performs the grip-opening of the hand, depending on the different degrees of pressing of the electrode system, is shown in Fig. 6.

EMG and MMG signals carry information about the degree of muscle contraction, and a joint analysis of EMG, MMG and impedance signals makes it possible to determine the type of action performed. As a result of the operation of the algorithm for the joint analysis of biosignals, the values of the current degree of action and its type are calculated, on the basis of which the corresponding control commands to the executive unit are formed.

Example 1. Controlling an exoskeleton

Electrode systems (units for recording biosignals, figure 1) are placed in the projections of the antagonist muscles. The operator carries out natural movements of these muscles (for example, flexion-unbend the hand). After calculating the degree of flexion of the hand in the control unit (10) of the unit for implementing control actions (Fig. 1), the signal is transmitted to the executive unit 12 (Fig. 1) - the drive of the exoskeleton. To control different types of movements, it is necessary to place two pairs of electrode systems on the corresponding antagonist muscles.

Example 2. Computer control (for example, sound volume)

Electrode systems (units for recording biosignals, Fig. 1) are placed in projections of antagonist muscles (for example, flexor-extensors of the hand) on a healthy arm or on a stump (if the operator is disabled). The calculated value of the current degree of flexion of the hand in the control unit (10) of the unit for implementing control actions (Fig. 1) is transmitted to the executive unit 12 (Fig. 1), which is connected to the computer via one of the standard interfaces (USB, serial port, IR port). Specialized computer software takes the received information about the degree of flexion of the hand and sets the sound volume equal to the current degree of flexion of the hand.

Claims (1)

A complex for bionic control of technical devices, containing a biosignal recording unit and a unit for implementing control actions connected in series to each other, containing a sequentially connected control unit and an executive unit, which is the output of the complex, in which the biosignal recording unit includes a current source, two outputs of which are connected respectively to two current electrodes, two measuring electrodes are connected to the inputs of the input amplifier, the output of which is the input of the units for processing the electromyogram (EMG) and impedance channels, respectively, characterized in that a mechanomyographic (MMG) channel sensor is inserted into the biosignal recording unit, powered by a reference voltage source , the signal from which is fed to the input amplifier, the output of which is connected in series to the input of the MMG processing unit, the outputs of the processing units of the EMG, impedance and introduced MMG channels are connected to the input of the signal registration unit, while a modem is introduced into the block for implementing control actions, it is made with the possibility of exchanging data with modems located in the blocks for registering biosignals.

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