Fatigue monitoring system and method for detecting skin impedance change based on sensor

Abstract

The invention discloses a fatigue monitoring system and method for detecting skin impedance change based on a sensor, and the system comprises a plurality of sensor units, each sensor unit comprises an acoustoelectric signal conversion module, an electrode, a piezoelectric crystal, a matching layer, and an acoustic lens; the integrated processing unit is connected with the sensor unit and used for receiving the electric signals from the sensor unit and processing and analyzing the electric signals; the display unit is connected with the integrated processing unit and used for displaying the fatigue state information of the driver; the alarm unit is connected with the integrated processing unit and used for giving an alarm when the fatigue state of the driver is detected; the sensor units are evenly distributed on the section of the steering wheel, each sensor unit is connected with the integrated processing unit through the wire harness, and the wire harness comprises a plurality of strands of wires and is used for transmitting electric signals and a power source. According to the fatigue monitoring system and method for detecting the skin impedance change based on the sensor, the fatigue state of a driver can be accurately monitored, and the road safety is improved.

Description

Technical Field

[0001] This invention belongs to the field of vehicle safety technology, specifically relating to a fatigue monitoring system and method based on sensor detection of changes in skin impedance. Background Technology

[0002] With the rapid development of modern society, automobiles have become an important means of transportation for people's daily travel. However, with the increase in car ownership, the incidence of traffic accidents is also showing an upward trend. Among the many causes of traffic accidents, driver fatigue is a significant factor that cannot be ignored. Fatigue leads to slowed reaction time and lack of concentration, thereby increasing the risk of accidents. According to statistics from the World Health Organization (WHO), more than 20% of all traffic accidents worldwide are caused by fatigue each year, a shocking figure.

[0003] To improve road safety and reduce traffic accidents caused by driver fatigue, governments and research institutions worldwide are seeking effective methods for fatigue monitoring. Currently, various fatigue monitoring technologies are available on the market, primarily including eye-tracking monitoring, head movement monitoring, and driving behavior analysis. These technologies determine whether a driver is fatigued by monitoring their eye movements, head posture, and driving behavior. However, these methods have certain limitations, such as low monitoring accuracy, susceptibility to external interference, and insufficient protection of driver privacy.

[0004] For example, while eye-tracking technology can determine driver fatigue by monitoring indicators such as eyelid closure frequency, its accuracy is affected by various factors, such as changes in lighting and the driver wearing glasses. Head motion monitoring technology is easily interfered with by external factors such as vehicle vibration, leading to misjudgments. Although driving behavior analysis technology can determine fatigue by analyzing driver behavior, it does not adequately protect driver privacy and may easily cause resentment among drivers.

[0005] Furthermore, most existing fatigue monitoring technologies require the installation of cameras and other equipment inside the vehicle, which not only increases vehicle costs but also infringes on driver privacy. Therefore, developing a new fatigue monitoring technology is of great significance for improving road safety and protecting driver privacy. Summary of the Invention

[0006] This invention provides a fatigue monitoring system and method based on sensor detection of changes in skin impedance to solve the technical problem of inaccuracy in traditional early warning methods mentioned above. Specifically, the technical solution is as follows:

[0007] A fatigue monitoring system based on sensor detection of changes in skin impedance includes:

[0008] Multiple sensor units are mounted on the steering wheel. Each sensor unit includes an acoustic-electric signal conversion module, electrodes, a piezoelectric crystal, a matching layer, and an acoustic lens.

[0009] An integrated processing unit, connected to the sensor unit, is used to receive electrical signals from the sensor unit and to process and analyze them.

[0010] The display unit, connected to the integrated processing unit, is used to display the driver's fatigue status information;

[0011] An alarm unit, connected to the integrated processing unit, is used to issue an alarm when driver fatigue is detected.

[0012] The sensor units are evenly distributed on the cross-section of the steering wheel. Each sensor unit is connected to the integrated processing unit via a wiring harness, which includes multiple wires for transmitting electrical signals and power.

[0013] Furthermore, the number of sensor units is eight, evenly distributed around the 360-degree circumference of the steering wheel, to achieve comprehensive detection of the driver's hand skin and ensure accurate detection in any grip position.

[0014] Furthermore, the eight sensor units are evenly distributed around the 360-degree circumference of the steering wheel, and a single-line aperture is formed in the central region.

[0015] Furthermore, the acoustic-to-electrical signal conversion module includes a signal amplifier and a filter, which are used to amplify and filter the received electrical signal to improve the signal quality and reliability and ensure the stability of the signal during transmission.

[0016] Furthermore, the piezoelectric crystal is made of piezoelectric ceramic material, which has good piezoelectric effect and mechanical stability, and can generate stable mechanical vibration under the action of electrical signal, ensuring the accuracy of ultrasonic wave transmission and reception.

[0017] Furthermore, the sensor unit also includes sound-absorbing material located on the side or back of the sensor unit to absorb unwanted sound waves, reduce interference, and improve the signal-to-noise ratio of the system.

[0018] Furthermore, the acoustic impedance of the matching layer is between that of the piezoelectric crystal and the measured medium, which is used to reduce the reflection of sound waves at the interface, improve the transmission efficiency of sound waves, and ensure the effective utilization of ultrasound.

[0019] Furthermore, the acoustic lens is used to focus or diffuse ultrasonic waves, adjusting the propagation direction and intensity of the sound waves to adapt to different detection needs and improve the flexibility and accuracy of detection.

[0020] A fatigue monitoring method based on sensor detection of skin impedance changes, based on the aforementioned fatigue monitoring system based on sensor detection of skin impedance changes, includes the following steps:

[0021] An electrical signal is generated by an acoustic-to-electrical signal conversion module, which is then transmitted to a piezoelectric crystal via electrodes, causing the piezoelectric crystal to vibrate mechanically and emit ultrasonic waves.

[0022] The ultrasound waves act on the driver's hand skin through a matching layer and an acoustic lens;

[0023] The ultrasonic waves reflected from the driver's skin are received, transmitted through an acoustic lens and a matching layer to a piezoelectric crystal, which converts the mechanical vibration into an electrical signal, which is then transmitted through electrodes to an acoustic-electric signal conversion module.

[0024] The driver's fatigue state is determined based on the strength and characteristics of the received electrical signal. The determination process includes digital processing of the signal to improve the accuracy of the determination.

[0025] Furthermore, the determination of fatigue state is based on the strength and characteristics of the received electrical signal, including but not limited to the amplitude, frequency and phase changes of the signal, as well as the duration and trend of the signal, in order to comprehensively assess the driver's fatigue level.

[0026] The fatigue monitoring system and method based on sensor detection of skin impedance changes provided by this invention can accurately monitor driver fatigue and improve road safety. This invention provides a fatigue monitoring system and method based on sensor detection of skin impedance changes. By installing a sensor unit on the steering wheel, it monitors the impedance changes of the driver's hand skin to determine the driver's fatigue state. This method not only improves monitoring accuracy but also protects driver privacy, and has broad application prospects. The implementation of this invention is expected to significantly reduce the incidence of traffic accidents caused by fatigued driving and improve road safety. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a fatigue monitoring system based on sensor detection of changes in skin impedance according to the present invention;

[0029] Figure 2 This is a schematic diagram of the sensor unit of the present invention mounted on the steering wheel;

[0030] Figure 3 This is a schematic diagram of the sensor unit of the present invention. Detailed Implementation

[0031] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0032] like Figure 1 The disclosed system is a fatigue monitoring system based on sensor detection of changes in skin impedance, comprising: multiple sensor units, an integrated processing unit, a display unit, and an alarm unit.

[0033] like Figure 2-3 As shown, multiple sensor units are mounted on the steering wheel. Each sensor unit includes an acoustic-to-electrical signal conversion module, electrodes, a piezoelectric crystal, a matching layer, and an acoustic lens. The sensor units are evenly distributed across the cross-section of the steering wheel, and each sensor unit is connected to an integrated processing unit via a wiring harness. The wiring harness includes multi-strand wires for transmitting electrical signals and power.

[0034] The integrated processing unit is connected to the sensor unit to receive, process, and analyze electrical signals from the sensor unit. Preferably, the integrated processing unit includes a signal amplifier, a filter, a digitization module, and a fatigue state determination module.

[0035] The display unit is connected to the integrated processing unit and is used to display driver fatigue information. The display unit can be a screen on the instrument panel or a head-up display system.

[0036] The alarm unit is connected to the integrated processing unit and is used to issue an alert when driver fatigue is detected. The alarm unit can be an audible alarm or a visual alarm.

[0037] In the embodiments of this application, the acoustic-to-electrical signal conversion module includes a signal amplifier and a filter, which are used to amplify and filter the received electrical signal to improve the signal quality and reliability and ensure the stability of the signal during transmission.

[0038] In the embodiments of this application, the piezoelectric crystal is made of piezoelectric ceramic material, which has good piezoelectric effect and mechanical stability, and can generate stable mechanical vibration under the action of electrical signal, thus ensuring the accuracy of ultrasonic wave transmission and reception.

[0039] In embodiments of this application, the sensor unit further includes sound-absorbing material located on the side or back of the sensor unit to absorb unwanted sound waves, reduce interference, and improve the signal-to-noise ratio of the system.

[0040] In the embodiments of this application, the acoustic impedance of the matching layer is between the piezoelectric crystal and the medium under test, which is used to reduce the reflection of sound waves at the interface, improve the transmission efficiency of sound waves, and ensure the effective utilization of ultrasound.

[0041] In the embodiments of this application, an acoustic lens is used to focus or diffuse ultrasonic waves, adjust the propagation direction and intensity of the sound waves to adapt to different detection needs, and improve the flexibility and accuracy of detection.

[0042] System working principle:

[0043] Ultrasonic emission: An electrical signal is generated by an acoustic-to-electrical signal conversion module, which is then transmitted to a piezoelectric crystal via electrodes, causing the piezoelectric crystal to vibrate mechanically and emit ultrasonic waves.

[0044] Ultrasonic wave propagation: Ultrasonic waves pass through a matching layer and an acoustic lens and act on the driver's hand skin.

[0045] Ultrasonic receiver: Receives ultrasonic waves reflected from the driver's skin, transmits them through an acoustic lens and matching layer to a piezoelectric crystal, which converts the mechanical vibration into an electrical signal, which is then transmitted to the acoustic-electric signal conversion module via electrodes.

[0046] Signal processing: The integrated processing unit amplifies, filters, and digitizes the received electrical signals.

[0047] Fatigue state assessment: The driver's fatigue state is determined based on the intensity and characteristics of the received electrical signals. This assessment process includes digital processing of the signals to improve the accuracy of the assessment.

[0048] The results show that the display unit shows the driver's fatigue status information.

[0049] Alarm: The alarm unit will sound an alarm when driver fatigue is detected.

[0050] The following is a specific embodiment that details the implementation process of the present invention:

[0051] Example 1: As Figure 2-3 As shown, in one embodiment, eight sensor units are mounted on the steering wheel, evenly distributed around its 360-degree circumference. Each sensor unit includes an acoustic-to-electrical signal conversion module, electrodes, a piezoelectric crystal, a matching layer, and an acoustic lens. These sensor units are connected to an integrated processing unit via a wiring harness comprising multi-strand wires for transmitting electrical signals and power.

[0052] The integrated processing unit includes a signal amplifier, a filter, a digitization module, and a fatigue state assessment module. The signal amplifier and filter amplify and filter the received electrical signal to improve its quality and reliability. The digitization module converts the analog signal into a digital signal for further processing. The fatigue state assessment module determines the driver's fatigue state based on the intensity and characteristics of the received electrical signal.

[0053] The display unit can be a screen on the instrument panel or a head-up display system, used to display driver fatigue information. The alarm unit can be an audible alarm or a visual alarm, used to issue an alert when driver fatigue is detected.

[0054] Specifically, sound pressure refers to the instantaneous change in pressure within a medium when sound waves are propagating, relative to the static pressure when there are no sound waves. Its unit is Pascal (Pa). Acoustic impedance is a physical quantity describing the degree to which a medium impedes the propagation of sound waves. It is equal to the ratio of sound pressure in the medium to the vibration velocity of the medium's particles, as shown in the following formula:

[0055] in, It is acoustic impedance, and the unit is Rayleigh or Pa·s / m. For sound pressure, It is the vibration velocity of the medium particles. For a lossless homogeneous medium, the acoustic impedance can also be determined by the inherent properties of the medium:

[0056] Z = ρ × c

[0057] Where ρ is the density of the tissue, and c is the speed at which ultrasound waves propagate through that tissue. The Z-dimensional values ​​calculated by the two formulas above are consistent. An example (approximate value) of the acoustic impedance of common human tissues, such as air: ~0.0004 × 10⁻⁶ 6 Rayl, water: 1.48×10 6 Rayl, fat: ~1.38 × 10 6 Rayl, soft tissue (average): ~1.63 × 10 6 Rayl, skeleton: ~7.8 × 10 6 Rayl.

[0058] Assuming a lossless, homogeneous medium during the propagation from organization 1 to organization 2,

[0059] =

[0060] =

[0061] Assuming perpendicular incidence, then,

[0062] Sound pressure transmission coefficient:

[0063] Sound pressure reflection coefficient: R = 1 - =

[0064] Sound intensity (power) reflection coefficient: R2 =

[0065] For example, the acoustic impedance of air is 0.000429 × 10⁻⁶, which is transmitted from the probe into the air and then to the skin. 6 Rayl, skin acoustic impedance 1.63 × 10⁻⁶ 6 Rayl, sound intensity (power) reflection coefficient is: .

[0066] The probe's tip is designed to have an acoustic impedance similar to that of human soft tissue. This means that when there is an air gap between the probe and the skin, most (99%) of the acoustic energy is reflected back at the probe-air interface. Even energy conducted into the air is reflected back at the tissue interface. In other words, as long as there is air between the probe and the tissue, almost all the energy is reflected back. When a person is fatigued, their palms are sweaty and damp, while other parts of the hand are dry. Therefore, the reflected energy is lowest in the palms and highest in other areas. Assume the emitted energy (power unit) of these 8 sensors is E-out-1,…E-out-8, and the reflected energy is E-back-1,…E-out-8, with differences of Delta-1,…Delta-8. Under normal conditions, most probes reflect high energy (close to zero). Under fatigue, the reflected energy is very low (close to 0) in sweaty areas and higher in dry areas (compared to normal conditions). Therefore, the difference is reflected in the variance, which is calculated as follows:

[0067]

[0068] A threshold T is set; when std > T, fatigue is considered; otherwise, normal operation is considered. The value of T is determined experimentally.

[0069] Example 2: In another embodiment, the number of sensor units is increased to 12 to further improve detection accuracy and coverage. These sensor units are evenly distributed around the 360-degree circumference of the steering wheel, and a wire harness aperture is formed in the central area to facilitate the arrangement and connection of the wiring harness.

[0070] Example 3: In the third embodiment, the acoustic-to-electrical signal conversion module includes a high-precision signal amplifier and a low-pass filter for high-precision amplification and filtering of the received electrical signal. The piezoelectric crystal uses high-performance piezoelectric ceramic material, which has good piezoelectric effect and mechanical stability, and can generate stable mechanical vibration under the action of electrical signal, ensuring the accuracy of ultrasonic wave transmission and reception.

[0071] Example 4: In the fourth example, high-performance sound-absorbing foam is used as the sound-absorbing material, located on the side or back of the sensor unit, to absorb unwanted sound waves, reduce interference, and improve the signal-to-noise ratio of the system. The acoustic impedance of the matching layer is precisely designed, falling between that of the piezoelectric crystal and the measured medium, to reduce sound wave reflection at the interface, improve sound wave transmission efficiency, and ensure the effective utilization of ultrasound.

[0072] Example 5: In the fifth example, the acoustic lens uses high-precision acoustic materials to focus or diffuse ultrasonic waves, adjust the propagation direction and intensity of the sound waves to adapt to different detection needs, and improve the flexibility and accuracy of detection.

[0073] Through the above embodiments, it can be seen that the fatigue monitoring system on the steering wheel based on sensor detection of skin impedance changes of the present invention has the advantages of simple structure, high detection accuracy, and good reliability. It can accurately monitor the driver's fatigue state and improve road safety.

[0074] Based on the aforementioned fatigue monitoring system that detects changes in skin impedance using sensors, this application also discloses a fatigue monitoring method that detects changes in skin impedance using sensors, comprising the following steps:

[0075] An electrical signal is generated by an acoustic-to-electrical signal conversion module, which is then transmitted to a piezoelectric crystal via electrodes, causing the piezoelectric crystal to vibrate mechanically and emit ultrasonic waves.

[0076] The ultrasound waves act on the driver's hand skin through a matching layer and an acoustic lens.

[0077] The ultrasonic waves reflected from the driver's skin are received, transmitted through an acoustic lens and a matching layer to a piezoelectric crystal, which converts the mechanical vibration into an electrical signal, which is then transmitted through electrodes to an acoustic-electric signal conversion module.

[0078] The driver's fatigue state is determined based on the strength and characteristics of the received electrical signals. The determination process includes digital processing of the signals to improve the accuracy of the determination.

[0079] In the embodiments of this application, the determination of fatigue state is based on the strength and characteristics of the received electrical signal, including but not limited to the amplitude, frequency and phase changes of the signal, as well as the duration and trend of the signal, in order to comprehensively assess the driver's fatigue level.

[0080] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A fatigue monitoring system based on sensor detection of changes in skin impedance, characterized in that, include: Multiple sensor units are mounted on the steering wheel. Each sensor unit includes an acoustic-electric signal conversion module, electrodes, a piezoelectric crystal, a matching layer, and an acoustic lens. An integrated processing unit, connected to the sensor unit, is used to receive electrical signals from the sensor unit and to process and analyze them. The display unit, connected to the integrated processing unit, is used to display the driver's fatigue status information; An alarm unit, connected to the integrated processing unit, is used to issue an alarm when driver fatigue is detected. The sensor units are evenly distributed on the cross-section of the steering wheel. Each sensor unit is connected to the integrated processing unit via a wiring harness, which includes multiple wires for transmitting electrical signals and power.

2. The fatigue monitoring system based on sensor detection of skin impedance changes according to claim 1, characterized in that, The sensor unit consists of eight units, evenly distributed around the 360-degree circumference of the steering wheel, to achieve comprehensive detection of the driver's hand skin and ensure accurate detection in any grip position.

3. The fatigue monitoring system based on sensor detection of skin impedance changes according to claim 1, characterized in that, The eight sensor units are evenly distributed around the 360-degree circumference of the steering wheel, and form a single-line aperture in the central region.

4. The fatigue monitoring system based on sensor detection of skin impedance changes according to claim 1, characterized in that, The acoustic-electric signal conversion module includes a signal amplifier and a filter, which are used to amplify and filter the received electrical signal to improve the signal quality and reliability and ensure the stability of the signal during transmission.

5. The fatigue monitoring system based on sensor detection of skin impedance changes according to claim 1, characterized in that, The piezoelectric crystal is made of piezoelectric ceramic material, which has good piezoelectric effect and mechanical stability. It can generate stable mechanical vibration under the action of electrical signals, ensuring the accuracy of ultrasonic wave transmission and reception.

6. The fatigue monitoring system based on sensor detection of skin impedance changes according to claim 1, characterized in that, The sensor unit also includes sound-absorbing material located on the side or back of the sensor unit to absorb unwanted sound waves, reduce interference, and improve the signal-to-noise ratio of the system.

7. The fatigue monitoring system based on sensor detection of skin impedance changes according to claim 1, characterized in that, The acoustic impedance of the matching layer is between that of the piezoelectric crystal and the measured medium, which is used to reduce the reflection of sound waves at the interface, improve the transmission efficiency of sound waves, and ensure the effective utilization of ultrasound.

8. The fatigue monitoring system based on sensor detection of skin impedance changes according to claim 1, characterized in that, The acoustic lens is used to focus or diffuse ultrasonic waves, adjusting the propagation direction and intensity of the sound waves to adapt to different detection needs and improve the flexibility and accuracy of detection.

9. A fatigue monitoring method based on sensor detection of skin impedance changes, based on the fatigue monitoring system based on sensor detection of skin impedance changes according to any one of claims 1 to 8, characterized in that, Includes the following steps: An electrical signal is generated by an acoustic-to-electrical signal conversion module, which is then transmitted to a piezoelectric crystal via electrodes, causing the piezoelectric crystal to vibrate mechanically and emit ultrasonic waves. The ultrasound waves act on the driver's hand skin through a matching layer and an acoustic lens; The ultrasonic waves reflected from the driver's skin are received, transmitted through an acoustic lens and a matching layer to a piezoelectric crystal, which converts the mechanical vibration into an electrical signal, which is then transmitted through electrodes to an acoustic-electric signal conversion module. The driver's fatigue state is determined based on the strength and characteristics of the received electrical signal. The determination process includes digital processing of the signal to improve the accuracy of the determination.

10. The fatigue monitoring method based on sensor detection of skin impedance changes according to claim 9, characterized in that, The assessment of fatigue status is based on the strength and characteristics of the received electrical signals, including but not limited to changes in the amplitude, frequency, and phase of the signals, as well as the duration and trend of the signals, in order to comprehensively evaluate the driver's fatigue level.

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