Functional electrical stimulation device for bi-directional neural interface

Abstract

The invention relates to a functional electrical stimulation device for a bidirectional nerve interface. The functional electrical stimulation device comprises a power supply system for supplying power to the whole device; the boost power supply circuit is used for generating 100V voltage to realize high-voltage output; the high-voltage control circuit is used for isolating high voltage from a human body and ensuring that the high voltage is in contact with the human body only during electrical stimulation; the constant current output circuit is used for ensuring that the stimulation current is constant and does not change along with the change of the load impedance; the stimulation protection circuit is used for impedance matching to avoid large-current stimulation output at a stimulation interface under the condition that the control end is suspended; the neuromuscular stimulation interface is used for exporting stimulation current and acts on a human body by being connected with the stimulation electrode; the control enhancement circuit is used for amplifying a voltage intensity control signal and improving the system control precision; and the integrated control unit is used for generating a voltage intensity control signal and a high-voltage control signal to realize overall control of the functional electrical stimulation device.

Description

Technical Field

[0001] The present invention relates to the field of intelligent rehabilitation equipment, in particular to a functional electrical stimulation device for a bidirectional neural interface. Background Art

[0002] With the aging of the population and the impact of diseases such as stroke and hemiplegia, the number of people with limb injuries is increasing year by year. Reshaping damaged neural pathways and accelerating the reconstruction of limb motor function are effective ways to improve patients' quality of life. In recent years, intelligent rehabilitation devices represented by lower-limb assisted exoskeletons and hand function rehabilitation robots have been widely used due to their high efficiency and good repeatability. They mostly collect the patient's physiological information to perceive and control the patient's movement intentions, thereby improving the rehabilitation assistance efficiency of intelligent devices. However, due to the lack of an interactive channel between the device and the user, it is difficult to effectively and real-timely feedback the working status of the intelligent device to the user while the system is working, which greatly reduces the training effect of the system.

[0003] The bio-interface (BMI) is an intelligent human-computer interaction system that enables information transfer and interaction between biological organisms and electromechanical devices. It is an important way to bring intelligence to rehabilitation equipment. Currently, the feedback loop used in BMIs is mostly implemented in the form of electrical stimulation. However, existing electrical stimulation systems are prone to output fluctuations due to changes in skin impedance over long periods of use, resulting in poor stimulation effectiveness. Furthermore, due to the limited sensitivity of electrical stimulation responses, they are unable to meet the complex and precise control requirements of intelligent systems requiring bidirectional perception. Therefore, an electrical stimulation system with high stimulation accuracy and safe and stable output is needed to meet the perception and control requirements of bidirectional neural interfaces. Summary of the Invention

[0004] The purpose of the present invention is to provide a functional electrical stimulation device for a bidirectional neural interface, which has the characteristics of stable output, safety and reliability. It can be used in scenarios such as exoskeleton feedback and prosthetic limb control, and can realize bio-dynamic interaction by providing real-time feedback of bio-force information through electrical stimulation.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0006] A functional electrical stimulation device for a bidirectional neural interface, comprising: a boost power supply circuit, a high-voltage control circuit, a constant current output circuit, a stimulation protection circuit, a neuromuscular stimulation interface, a control enhancement circuit, an integrated control unit, and a power supply system, wherein:

[0007] The boost power supply circuit is respectively connected to the high-voltage control circuit and the constant-current output circuit. The integrated control unit is sequentially connected to the neuromuscular stimulation interface through the control enhancement circuit, the stimulation protection circuit, and the constant-current output circuit. The integrated control unit is also connected to the neuromuscular stimulation interface through the high-voltage control circuit. The power supply system is respectively connected to the boost power supply circuit, the constant-current output circuit, the control enhancement circuit, and the integrated control unit.

[0008] The boost power supply circuit includes a DC high-voltage isolation power supply module and its peripheral circuit, where:

[0009] The voltage input pin of the DC high-voltage isolation power supply module is used as the input end of the boost power supply circuit and is connected to the 12V lithium battery in the power supply system. The voltage output end of the DC high-voltage isolation power supply module is used as the output end of the boost power supply circuit. The voltage input end is respectively grounded through capacitors Cs1 and Cs2, and the voltage output end is grounded through capacitor Cs3.

[0010] The constant-current output circuit includes an operational amplifier U1A, a matching resistor R1, a field-effect transistor M1, and a sampling resistor R2, where:

[0011] The non-inverting input terminal of the operational amplifier U1A is used as the input end of the constant-current output circuit and is connected to the stimulation protection circuit. The output end of the operational amplifier U1A is connected to the gate of the field-effect transistor M1 through the matching resistor R1. The source of the field-effect transistor M1 is connected to the inverting input terminal of the operational amplifier U1A. The source of the field-effect transistor M1 is also grounded through the sampling resistor R2. The drain of the field-effect transistor M1 is used as the output end of the constant-current output circuit and is connected to the neuromuscular stimulation interface.

[0012] The stimulation protection circuit includes a series-connected resistor R5 and R6. One end of the resistor R5 is used as the input end of the stimulation protection circuit and is connected to the control enhancement circuit. One end of the resistor R5 is used as the output end of the stimulation protection circuit and is connected to the constant-current output circuit.

[0013] The control enhancement circuit includes a non-inverting proportional amplifier U2A, resistors R9, and R10, where:

[0014] The non-inverting input terminal of the non-inverting proportional amplifier U2A is used as the input end of the control enhancement circuit and is connected to the integrated control unit. The output end of the non-inverting proportional amplifier U2A is used as the output end of the control enhancement circuit and is connected to the stimulation protection circuit. The output end of the non-inverting proportional amplifier U2A is connected to the inverting input terminal of the non-inverting proportional amplifier U2A through the resistor R10. The inverting input terminal of the non-inverting proportional amplifier U2A is grounded through the resistor R9.

[0015] The power supply system includes a 5V step-down circuit, a 3.3V step-down circuit and a -5V negative voltage charge pump circuit respectively connected thereto, and also includes a 12V lithium battery connected to the 5V step-down circuit.

[0016] A functional electrical stimulation method for a bidirectional neural interface, comprising the following steps:

[0017] The boost power supply circuit boosts the current output by the power supply system and outputs it to the high-voltage control circuit and the constant-current output circuit;

[0018] The high-voltage control circuit controls the on / off of the electrical stimulation device according to the high-voltage control signal output by the integrated control unit;

[0019] The constant-current output circuit outputs a constant stimulation current;

[0020] The stimulation protection circuit performs impedance matching to reduce the reverse stimulation current in the circuit when the control terminal is floating;

[0021] The neuromuscular stimulation interface extracts the stimulation current and acts on the human body through the connected stimulation electrodes;

[0022] The control enhancement circuit amplifies the voltage intensity control signal output by the integrated control unit and transmits it to the constant-current output circuit;

[0023] The integrated control unit generates a voltage intensity control signal and a high-voltage control signal;

[0024] The power supply system supplies power to the boost power supply circuit, the constant-current output circuit, the control enhancement circuit, and the integrated control unit respectively.

[0025] The present invention has the following beneficial effects and advantages:

[0026] The present invention provides a functional electrical stimulation device for a bidirectional neural interface. The device adopts a constant current source design, which can greatly reduce the influence brought by the change of skin resistance during the stimulation feedback process; at the same time, it adopts a stimulation protection circuit design, which can effectively avoid the large current output between systems when the control terminal is floating, ensuring the safety of the system; in addition, through the control enhancement circuit design, the control precision of the system can be greatly improved, and the sensitivity of the feedback stimulation can be enhanced. Description of the Drawings

[0027] Figure 1 is a structural block diagram of a functional electrical stimulation device for a bidirectional neural interface according to the present invention;

[0028] Figure 2 is a schematic diagram of the boost circuit and the power supply module according to the present invention;

[0029] Figure 3 is a schematic diagram of the constant-current output circuit and the stimulation protection circuit according to the present invention;

[0030] Figure 4 is a schematic diagram of the control enhancement circuit according to the present invention. Detailed Embodiments

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0032] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0034] As Figure 1 shown is a structural block diagram of a neuromuscular stimulation system with an electromyogram feedback function according to the present invention.

[0035] A functional electrical stimulation device for a bidirectional neural interface includes the following parts:

[0036] A boost power supply circuit 1 is used to generate a 100V voltage to achieve electrical stimulation output; a high-voltage control circuit 2 is used to isolate the high voltage from the human body to ensure that the high voltage contacts the human body only during electrical stimulation; a constant current output circuit 3 is used to ensure that the stimulation current is constant and does not change with the change of the load impedance; a stimulation protection circuit 4 is used for impedance matching to avoid large current stimulation output at the stimulation interface when the control end is floating; a neuromuscular stimulation interface 5 is used to export the stimulation current and act on the human body through connecting stimulation electrodes; a control enhancement circuit 6 is used to amplify the voltage intensity control signal to improve the system control accuracy; an integrated control unit 7 is used to generate the voltage intensity control signal and the high-voltage control signal to achieve the overall control of the functional electrical stimulation device; a power supply system 8 is used to supply power to the boost power supply circuit 1, the constant current output circuit 3, the control enhancement circuit 6, and the integrated control unit 7.

[0037] As Figure 2 shown is a schematic diagram of the boost circuit and the power supply module of the present invention.

[0038] The described boost power supply circuit 1 is composed of a DC high-voltage isolation power module HRB12100D-8W. After boosting the 12V DC voltage to 100V through pulse rectification, it is transmitted to the high-voltage control circuit 2 for high-voltage control. The high-voltage control circuit 2 is mainly implemented through an optocoupler, which realizes the coupling and transmission of electrical signals through optical signals as a medium. At the input end, the on-off of the 100V high voltage at the output end is controlled by a PWM signal, thereby achieving the purpose of isolating the human body from high voltage and ensuring the safety of the system.

[0039] The power supply module 8 is composed of a 12V lithium battery pack, and realizes ±5V and 3.3V DC voltages through a buck circuit and a reverse charge pump circuit. Among them, the 12V voltage is used as the input of the boost power supply circuit 1; the +5V and -5V voltages act on the constant current output circuit 3 and the control enhancement circuit 6 to provide bipolar voltages for the operational amplifiers in the circuit; the 3.3V is used to supply power to the integrated control unit 7 for this module.

[0040] The described 5V buck circuit includes a linear voltage regulator and its peripheral circuits, where:

[0041] The voltage input terminal of the linear voltage regulator serves as the input terminal of the 5V buck circuit and is connected to the 12V lithium battery. The voltage output terminal of the linear voltage regulator serves as the output terminal of the 5V buck circuit and is respectively connected to the 3.3V buck circuit and the -5V reverse voltage charge pump circuit. The voltage input terminal of the linear voltage regulator is grounded through a capacitor C1. The voltage input terminal of the linear voltage regulator is connected to the enable terminal. The feedback terminal of the linear voltage regulator is connected to its output terminal through a resistor R20, and the feedback terminal of the linear voltage regulator is also grounded through a resistor R21. The output terminal of the linear voltage regulator is grounded through a capacitor C2.

[0042] The described 3.3V buck circuit includes a low-dropout voltage regulator and its peripheral circuits, where:

[0043] The voltage input terminal of the low-dropout voltage regulator serves as the input terminal of the 3.3V buck circuit, is connected to the 5V buck circuit, and is grounded through a capacitor C3. The voltage output terminal of the low-dropout voltage regulator serves as the output terminal of the 3.3V buck circuit, is connected to the integrated control unit, and is grounded through a capacitor C4.

[0044] The described -5V reverse voltage charge pump circuit includes a voltage inverter and its peripheral circuits, where:

[0045] The voltage input terminal of the voltage inverter serves as the input terminal of the -5V reverse voltage charge pump circuit, is connected to the 5V buck circuit, and is grounded through a capacitor C6. The voltage output terminal of the voltage inverter serves as the output terminal of the -5V reverse voltage charge pump circuit, is respectively connected to the constant current output circuit and the control enhancement circuit, and is grounded through a capacitor C7. A flying capacitor C5 is connected between pins 3 and 5 of the inverter chip.

[0046] AsFigure 3 The schematic diagram of the constant current output circuit and the stimulation protection circuit of the present invention is shown as follows.

[0047] Among them, the constant current output circuit 3 includes an operational amplifier U1A, a matching resistor R1, a field effect transistor M1, and a sampling resistor R2. The output terminal of U1A is connected to the first terminal of the matching resistor R1. The second terminal of the matching resistor R1 is connected to the gate of the field effect transistor M1. The source of the field effect transistor M1 is connected to the inverting input terminal of the operational amplifier U1A to form a voltage feedback. At the same time, the source of the field effect transistor M1 is also connected to the first terminal of the sampling resistor R2, and the second terminal of the sampling resistor R2 is grounded. The function of the sampling resistor is to adjust the magnitude of the output current in the circuit. The drain of the field effect transistor M1 is connected to the neuromuscular stimulation interface 5. When the load resistance at the neuromuscular stimulation interface 5 changes, according to the virtual short and virtual open principles of the operational amplifier, the voltage acting on the sampling resistor R2 is numerically equal to the reference voltage Vn at the input terminal of the operational amplifier U1A. At this time, the current I flowing through the sampling resistor R2 = Vn / R2. Also, since the source current and drain current of the field effect transistor are equal, the stimulation current flowing through the neuromuscular stimulation interface 5 always remains constant and does not change with the change of the load resistance at the neuromuscular stimulation interface 5. The sampling resistor R2 is an adjustable resistor, and the amplitude range of the stimulation current can be correspondingly adjusted by adjusting the resistance value; the field effect transistor M1 is an N-channel enhancement type.

[0048] The stimulation protection circuit 4 is composed of R5 and R6. When the output terminal of the D / A converter is in a floating state, the resistor R6 can play a current shunting role. Since the resistance value of R6 is much larger than that of R2, the current flowing through the sampling resistor R2 is much smaller than that at the R6 terminal. Furthermore, the stimulation current in the circuit can be greatly reduced to ensure the safety of the system.

[0049] The neuromuscular stimulation interface 5 is used to carry the stimulation current of the system and directly act on the surface of the human muscle, and is responsible for outputting electrical stimulation pulses. The control enhancement circuit 6 is composed of a non-inverting proportional amplifier, and the amplification factor is adjustable from 0 to 10 times, so as to achieve the purpose of improving the control accuracy of the system; Figure 4 The schematic diagram of the control enhancement circuit of the present invention.

[0050] The integrated control unit 7 is composed of a microcontroller minimum system, which is equipped with a D / A converter to output an analog voltage with a controllable amplitude, and the analog voltage is amplified by the control enhancement circuit 6 and then transmitted to the constant current output circuit 3 to complete the stimulation intensity control of the device; at the same time, the integrated control unit 7 also controls the working state of the high-voltage control circuit 2 by generating a PWM signal, thereby controlling the on and off of the electrical stimulation device and realizing the free adjustment of the pulse width and frequency of the electrical stimulation.

Claims

1. A functional electrical stimulation device for a bidirectional neural interface, characterized in that, Comprising: A boost power supply circuit (1), a high-voltage control circuit (2), a constant-current output circuit (3), a stimulation protection circuit (4), a neuromuscular stimulation interface (5), a control enhancement circuit (6), an integrated control unit (7), and a power supply system (8), wherein: The boost power supply circuit (1) is respectively connected to the high-voltage control circuit (2) and the constant-current output circuit (3). The integrated control unit (7) is sequentially connected to the neuromuscular stimulation interface (5) through the control enhancement circuit (6), the stimulation protection circuit (4), and the constant-current output circuit (3). The integrated control unit (7) is also connected to the neuromuscular stimulation interface (5) through the high-voltage control circuit (2). The power supply system (8) is respectively connected to the boost power supply circuit (1), the constant-current output circuit (3), the control enhancement circuit (6), and the integrated control unit (7).

2. The functional electrical stimulation device for a bidirectional neural interface according to claim 1, wherein, The boost power supply circuit (1) includes a DC high-voltage isolation power module and its peripheral circuit, wherein: The voltage input pin of the DC high-voltage isolation power module serves as the input end of the boost power supply circuit (1) and is connected to the 12V lithium battery in the power supply system (8). The voltage output end of the DC high-voltage isolation power module serves as the output end of the boost power supply circuit (1). The voltage input end is respectively grounded through capacitors Cs1 and Cs2, and the voltage output end is grounded through capacitor Cs3.

3. The functional electrical stimulation device for a bidirectional neural interface according to claim 1, wherein The constant-current output circuit (3) includes an operational amplifier U1A, a matching resistor R1, a field-effect transistor M1, and a sampling resistor R2, wherein: The non-inverting input terminal of the operational amplifier U1A serves as the input end of the constant-current output circuit (3) and is connected to the stimulation protection circuit (4). The output terminal of the operational amplifier U1A is connected to the gate of the field-effect transistor M1 through the matching resistor R1. The source of the field-effect transistor M1 is connected to the inverting input terminal of the operational amplifier U1A. The source of the field-effect transistor M1 is also grounded through the sampling resistor R2. The drain of the field-effect transistor M1 serves as the output end of the constant-current output circuit (3) and is connected to the neuromuscular stimulation interface (5).

4. The functional electrical stimulation device for a bidirectional neural interface according to claim 1, wherein The stimulation protection circuit (4) includes a series-connected resistor R5 and R6. One end of the resistor R5 serves as the input end of the stimulation protection circuit (4) and is connected to the control enhancement circuit (6). One end of the resistor R5 serves as the output end of the stimulation protection circuit (4) and is connected to the constant-current output circuit (3).

5. The functional electrical stimulation device for a bidirectional neural interface according to claim 1, characterized in that, The control enhancement circuit (6) includes a non-inverting proportional amplifier U2A, resistors R9, and R10, wherein: The non-inverting input terminal of the non-inverting proportional amplifier U2A serves as the input end of the control enhancement circuit (6) and is connected to the integrated control unit (7). The output terminal of the non-inverting proportional amplifier U2A serves as the output end of the control enhancement circuit (6) and is connected to the stimulation protection circuit (4). The output terminal of the non-inverting proportional amplifier U2A is connected to the inverting input terminal of the non-inverting proportional amplifier U2A through the resistor R10. The inverting input terminal of the non-inverting proportional amplifier U2A is grounded through the resistor R9.

6. The functional electrical stimulation device for a bidirectional neural interface according to claim 1, wherein The power supply system (8) includes a 5V step-down circuit, a 3.3V step-down circuit and a -5V reverse voltage charge pump circuit respectively connected thereto, and also includes a 12V lithium battery connected to the 5V step-down circuit.

7. A functional electrical stimulation method for a bidirectional neural interface, characterized in that, Comprising the following steps: The boost power supply circuit (1) boosts the current output by the power supply system (8) and outputs it to the high-voltage control circuit (2) and the constant-current output circuit (3); The high-voltage control circuit (2) controls the on / off of the electrical stimulation device according to the high-voltage control signal output by the integrated control unit (7); The constant-current output circuit (3) outputs a constant stimulation current; The stimulation protection circuit (4) performs impedance matching to reduce the reverse stimulation current in the circuit when the control terminal is floating; The neuromuscular stimulation interface (5) conducts the stimulation current and acts on the human body through the connected stimulation electrodes; The control enhancement circuit (6) amplifies the voltage intensity control signal output by the integrated control unit (7) and transmits it to the constant-current output circuit (3); The integrated control unit (7) generates a voltage intensity control signal and a high-voltage control signal; The power supply system (8) supplies power to the boost power supply circuit (1), the constant-current output circuit (3), the control enhancement circuit (6), and the integrated control unit (7) respectively.

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