A finger bending degree measurement method and system based on human body surface capacitance

Abstract

The application relates to the technical field of hand action capture, and discloses a finger bending degree measurement method and system based on human body surface capacitance. The finger bending degree measurement method based on human body surface capacitance comprises the following steps: a user selects a working mode, a system inputs finger bending model parameters; the system samples sensor data under each finger bending state and obtains corresponding parameters; the system calculates reference threshold values according to the corresponding parameters; and the system judges a motion state according to the reference threshold values. The application can simply and effectively measure the bending degree of fingers by using a bracelet and ring assembly, and can realize hand action capture by cooperating with an acceleration sensor.

Description

Technical Field

[0001] This invention relates to the field of hand motion capture technology, and in particular to a method and system for measuring finger curvature based on the capacitance of the human body surface. Background Technology

[0002] With the rise of the metaverse, sensing devices used for motion capture and posture measurement are receiving increasing attention as important human-computer interaction platforms. For hand motion capture, existing technologies mostly utilize gloves, sensor suits, and optical sensors to capture hand joint movements. However, their high technical barriers and expensive prices hinder widespread adoption and promotion. Sensor gloves, on the other hand, suffer from problems such as poor breathability, high cost, and difficulty in everyday wear, thus hindering their commercial application.

[0003] Therefore, this invention proposes a method and system for measuring finger curvature based on the capacitance of the human body surface. It can simply and effectively measure the degree of finger curvature using a combination of a bracelet and a ring. Combined with an accelerometer and a gyroscope, it can achieve hand motion capture. Summary of the Invention

[0004] To address the issues of breathability, high cost, and inconvenience for daily wear in the field of hand motion capture using sensor gloves, this invention provides a finger curvature measurement system based on human skin surface capacitance. The system includes a microprocessor, a skin capacitance testing unit, a signal transmitting unit, a long wire, a wristband, and a ring. The wristband is positioned on the user's wrist and has inner and outer electrodes made of materials that allow AC signals to pass through. The inner electrode contacts the user's skin and is electrically connected to a skin capacitance testing circuit. The skin capacitance testing unit includes a signal transmitting unit and a signal detecting unit, configured to detect skin capacitance values ​​and output capacitance signals based on the user's finger movements. One end of the long wire is electrically connected to the ring, and the other end is connected to the skin capacitance testing unit. Additionally, the system includes an accelerometer electrically connected to the microprocessor, configured to generate electrical signals based on the user's wrist movements. The microprocessor, electrically connected to the skin capacitance testing unit, accelerometer, and signal transmitting unit, is configured to determine the user's finger movements based on the capacitance signals and the user's hand position based on the electrical signals.

[0005] A method for measuring finger flexure based on human body surface capacitance includes: S1. The system starts, the user selects the working mode, and the system inputs finger flexure model parameters; S2. The system samples sensor data for each finger state and obtains corresponding parameters; S3. The system calculates a reference threshold based on the corresponding parameters; S4. The system determines the motion state based on the reference threshold.

[0006] Furthermore, step S2 includes the following sub-steps: S21. Obtain skin capacitance test unit data, process it to obtain skin capacitance parameters; S22. Convert the above skin capacitance parameters into capacitance change gradient parameters; S23. Process and record the capacitance change gradient parameters.

[0007] Furthermore, step S4 includes the following sub-steps: S41. The system calculates finger bending parameters based on sensor parameters and a reference threshold; S42. The system processes the finger bending parameters and the finger bending model parameters to obtain the user's hand state; S43. The system outputs the user's hand state. In step S41, the sensor parameters include: A. Skin capacitance testing unit parameters, and B. Capacitance change gradient parameters.

[0008] This invention provides a method and system for measuring finger curvature based on human body surface capacitance, which has the following beneficial effects:

[0009] (1) The present invention uses finger skin capacitance data to reflect the degree of finger bending. By first setting a capacitance gradient threshold, the finger movement is judged based on the capacitance value, achieving real-time performance, accuracy and intelligence.

[0010] (2) This invention does not require the use of heavy equipment such as gloves. It can use the user's own ring as an electrode, which is convenient to use and easy to wear in daily life.

[0011] (3) With the structure of the present invention, the relevant key data of the wristband can be collected and processed by the system in a timely manner, so that more accurate hand status information can be fed back to the user. At the same time, it can integrate functions such as touch object sensing and information transmission, which is more promising. Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating a method according to some embodiments of this specification;

[0013] Figure 2 This is a schematic diagram of the system structure according to some embodiments of this specification;

[0014] Figure 3 This is a schematic diagram illustrating application scenarios of the measurement system according to some embodiments of this specification;

[0015] Figure 4 This is an exemplary structural diagram of a measurement system according to some embodiments of this specification;

[0016] Figure 5 Here are capacitance curves of the measurement system shown in some embodiments of this specification under different conditions;

[0017] Figure 6The following are capacitance curves of the measurement system shown in some embodiments of this specification under different conditions. Detailed Implementation

[0018] The following detailed description of the implementation method of the present invention is in conjunction with the accompanying drawings. The description is only a partial embodiment and not all embodiments. For clarity, representations and descriptions unrelated to the present invention are omitted in the drawings and description.

[0019] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the following detailed description of the technical solution of the present invention is provided. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them, and should not be construed as limiting the scope of implementation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0020] In some embodiments, such as Figure 2 As shown, the present invention provides a finger bending degree measurement system based on human body surface capacitance, including a microprocessor 12, a skin capacitance testing unit 11, an accelerometer 13, a signal transmitting unit 14, a long wire 3, a wristband 1, and a ring 2.

[0021] The wristband 1 is disposed on the user's wrist and has an inner electrode 15 and an outer electrode made of a material that allows AC signals to pass through. The inner material is in close contact with the user's skin and is electrically connected to the skin capacitance testing circuit. One end of the long wire 3 is electrically connected to the ring, and the other end is connected to the skin capacitance testing unit.

[0022] Optionally, the wristband electrode 15, which is in contact with the skin, can be the lower surface of a watch dial or a circular wristband. Preferably, the wristband electrode 15 is made of a conductive material with good conductivity.

[0023] In some embodiments, such as Figure 3 A schematic diagram of a measurement system application scenario in one embodiment shows that a microprocessor 12, a skin capacitance testing unit 11, an accelerometer 13, and a signal transmitting unit 14 are integrated inside a wristband. The skin capacitance testing unit 11 includes a signal transmitting unit 111 and a signal detection unit 112. The signal transmitting unit applies a sinusoidal AC signal to at least one stage of the wristband 1 and the ring 2. Preferably, the frequency threshold of the sinusoidal AC signal is between 50kHz and 250kHz, and the peak voltage is 5V.

[0024] The accelerometer is configured to generate an electrical signal based on the user's wrist movements.

[0025] The microprocessor 12 is electrically connected to the skin capacitance testing unit 11, the accelerometer 13, and the signal transmitting unit. The skin capacitance testing unit 11 and the accelerometer 13 transmit data information to the microprocessor 12 through electrical signals.

[0026] In some embodiments, the microprocessor 12 is configured to determine the user's hand movement posture based on information input from the skin capacitance testing unit 11 and the accelerometer 13. Optionally, when the user wears this system for exercise, the signal transmitting unit 111 emits a sinusoidal AC signal, the signal detection unit 112 detects the emitted AC signal, continuously measures the capacitance value of the user's finger surface, and the processor 12 determines the user's finger movement posture based on the change in capacitance value. For example, the movement angle of the finger joints can be established based on the signal detected by the skin capacitance testing unit 11 to establish a correspondence between the capacitance value of the user's finger surface and the user's finger movement posture, thereby realizing the measurement of the finger joint movement angle. In some embodiments, the hand movement posture includes, but is not limited to, finger joint movement angle, finger joint movement speed, palm movement speed, palm position, hand touching object detection, and individual finger movement states. In some embodiments, the finger joint movement angle includes, but is not limited to, the bending angle of one or a combination of the first, second, and third joints from the palm upwards, and the overall finger bending angle.

[0027] Optionally, the microprocessor 12 can output the user's hand position and movements through the signal transmitting unit 14.

[0028] Optionally, the signal transmitting unit 14 is an active transmitter that sends hand movement data collected by the microsensor 12 to a remote computing device.

[0029] In some embodiments, such as Figure 4 As shown, the number of long wires and ring electrodes may not be one. Figure 4 In one embodiment where five ring electrodes are worn, the microprocessor 12 distinguishes the skin capacitance values ​​of the ring electrodes 3 worn on different fingers by controlling the opening and closing states of different switches within a cycle, and measures the curvature information of the five different fingers of the hand. For example, if it is necessary to measure the capacitance value from wristband electrode 1 to ring electrode 21, the processor controls switch 31 to close and the other four switches to open. The capacitance testing unit 11 measures the corresponding capacitance value and converts it into an electrical signal, which is then sent to the processor. The microprocessor 12 determines the movement posture of the finger based on the change in capacitance value, and the same applies to the other fingers.

[0030] In some embodiments, the ring 2 may contain a built-in skin capacitance testing unit component, and the number of long wires 3 is zero. When the user initiates skin capacitance measurement, the microprocessor 12 in the wristband sends a measurement command to the skin capacitance testing unit 11, and simultaneously the signal transmitting unit 14 sends a coordinated measurement command to the skin capacitance testing unit component inside the ring. Upon receiving the command from the signal transmitting unit 14, the skin capacitance testing unit component inside the ring and the skin capacitance testing unit 12 in the wristband simultaneously transmit sinusoidal AC signals with the same frequency and constant phase difference to measure the signal phase difference between the ring electrode 2 and the wristband electrode 15. Preferably, the frequency of the sinusoidal AC signal is 50kHz. The skin capacitance testing unit 11 measures the change in the phase difference between the ring electrode 2 and the wristband electrode 15 relative to time, and calculates the capacitance phase angle change gradient based on this value. In some embodiments, the skin capacitance testing unit 11 may transmit a sinusoidal AC signal of a specific frequency independently. The skin capacitance testing unit component built into the ring 2 measures the capacitance phase angle between the ring electrode 2 and the wristband electrode 15 by measuring the phase change of the received sinusoidal AC signal.

[0031] Figure 5 and Figure 6 The capacitance curves of the measurement system shown in some embodiments of this specification under different conditions are illustrated in the following figures. Figure 5 In this embodiment, the wristband electrode 15 is a metal ring-shaped electrode. Figure 6 In this embodiment, the wristband electrode 15 is a metal strip-shaped dial electrode. The capacitance testing unit 13 simultaneously applies a sinusoidal alternating current with a frequency of 50kHz and a peak voltage of 5V to both the wristband electrode 15 and the ring electrode 2. The user's finger is subjected to four or five movement cycles under different motion scenarios: A1 slow bending, A2 rapid bending, A3 bending followed by stopping and then continuing to bend, and A4 prolonged bending. Each capacitance peak cycle in the figure represents the capacitance change value of one test. The horizontal axis represents the time the capacitance testing unit applies the test current to the finger, in seconds (s), and the vertical axis represents the capacitance value between the wristband electrode 15 and the ring electrode 2, in nF. Figure 5 As shown in Figure A1-1, when the user's finger joints perform a slow bending motion, the capacitance between the wristband electrode and the ring electrode increases at a slow rate; as shown in Figure A1-1... Figure 5 As shown in Figure A2-1, when the user's finger joints perform rapid bending movements, the capacitance between the wristband electrode and the ring electrode increases rapidly; as shown in Figure A2-1. Figure 5 As shown in A3-1, when a user's finger joint undergoes a rapid bending motion after initially stopping, the capacitance between the wristband electrode and the ring electrode first stops rising and then rises rapidly. Figure 5As shown in Figure A4, the capacitance between the wristband and ring electrodes remains essentially constant when the user's finger joints are bent for an extended period. Understandably, the capacitance gradually increases with the angle of finger bending. It should be noted that due to individual differences in skin capacitance, which varies with sweat, body contact, and posture, the capacitance is not a constant value. However, for a fixed frequency and voltage, the electrical properties of the human body generally differ by less than 10%. Because the human body's capacitance generally exhibits a momentary drop to its minimum value in response to contact interference (excluding liquids), contact interference does not affect the calculation of the capacitance gradient. Furthermore, the figure is only intended to illustrate the correspondence between various finger joints and the capacitance curves and is not intended to limit the application to any specific finger joint.

[0032] like Figure 1 As shown, a method for measuring finger flexure based on human body surface capacitance includes the following steps: S1. The system starts, the user selects the working mode, and the system inputs finger flexure model parameters; S2. The system samples sensor data for each finger state and obtains corresponding parameters; S3. The system calculates a reference threshold based on the corresponding parameters; S4. The system determines the motion state based on the reference threshold.

[0033] Optionally, the user can choose whether to reset the finger capacitance reference threshold. If the user chooses to reset the finger capacitance reference threshold, proceed to step S3; if the user chooses not to reset the finger capacitance reference threshold, proceed directly to step S4 without updating the reference threshold.

[0034] Optionally, step S3 includes the following sub-steps: S31. The system determines whether the reference threshold is determined; S32. The capacitance gradient parameters are processed and converted into the reference threshold.

[0035] Step S4 includes the following sub-steps: S41. The system calculates the finger bending parameters based on the sensor parameters and the reference threshold; S42. The system processes the finger bending parameters and the finger bending model parameters to obtain the user's hand state; S43. The system outputs the user's hand state. In some preferred embodiments, the sensor parameters are parameters such as hand acceleration sensor parameters, finger skin capacitance gradient parameters, and finger skin capacitance parameters.

[0036] Optionally, the user's finger state can be rapid bending, slow bending, vertical stillness, or bent stillness, and the hand state can be rapid lifting, stillness, or slow lifting.

[0037] Optionally, the finger bending model parameters can be preset values ​​stored in the microprocessor 12 in advance, or optimal values ​​calculated from data, and can be changed according to the actual signal.

[0038] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A finger bending measurement system based on human body surface capacitance, characterized in that, Includes a microprocessor, skin capacitance testing unit, first signal transmitting unit, wristband, ring, and long wire; The wristband is disposed on the user's wrist and has an inner electrode and an outer electrode made of a material that allows AC signals to pass through. The inner electrode contacts the skin of the user's wrist and is electrically connected to the skin capacitance testing unit. The skin capacitance testing unit includes a second signal transmitting unit and a signal detection unit. A sinusoidal AC signal is applied to at least one end of the wristband and the ring. The unit is configured to detect the skin capacitance value and output an electrical signal based on the user's finger movement. One end of the long wire is electrically connected to the ring, and the other end is electrically connected to the skin capacitance testing unit; The microprocessor is electrically connected to the skin capacitance testing unit and the first signal transmitting unit, and is configured to determine the user's finger movements based on the electrical signals. The electrical signal includes at least one signal generated by the change in capacitance of the finger skin surface caused by the movement of at least one knuckle of one of the user's fingers.

2. The system according to claim 1, characterized in that, Determining the user's finger movement based on the electrical signal includes: The microprocessor determines the overall bending angle of the finger based on the electrical signal.

3. The system according to claim 1, characterized in that... It also includes an accelerometer electrically connected to the microprocessor, configured to detect the user's wrist movement and output a signal based on the user's wrist movement.

4. The system according to claim 1, characterized in that, The frequency threshold of the sinusoidal AC signal is less than or equal to 100MHz.

5. A method for measuring finger curvature based on human body surface capacitance, based on the finger curvature measurement system based on human body surface capacitance according to any one of claims 1-4, characterized in that, Includes the following steps: S1. The system starts up, the user selects the working mode, and the system inputs the finger bending model parameters; S2. The system samples sensor data for each finger in its bent state and obtains the corresponding parameters; S3. The system calculates the reference threshold based on the relevant parameters; S4. The system determines the motion state based on a reference threshold; Step S2 includes the following sub-steps: S21. Obtain skin capacitance test unit data, process it to obtain skin capacitance parameters; S22. Convert the above skin capacitance parameters into capacitance change gradient parameters; S23. Process and record the gradient parameters of the capacitance change.

6. The method according to claim 5, characterized in that, Step S3 includes the following sub-steps: S31. The system determines whether the reference threshold is determined; S32. Process the capacitance gradient parameters and convert them into a reference threshold.

7. The method according to claim 5, characterized in that, Step S4 includes the following sub-steps: S41. The system calculates the finger bending parameters based on the sensor parameters and the reference threshold; S42. Process the above finger bending parameters and the above finger bending model parameters to obtain the user's finger bending state; S43. The system outputs the user's finger bending status.

8. The method according to claim 7, characterized in that, The sensor parameters in step S41 include: A. Skin capacitance testing unit parameters, and B. Capacitance change gradient parameters.

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