METHOD AND DEVICE FOR DETERMINING THE VITAL FUNCTIONS OF A VEHICLE OCCUPANT

Description

[0001] The present description relates to a method and a device for determining the vital functions of a vehicle occupant, wherein cardiogram signals of a vehicle occupant are determined contactlessly by a sensor device integrated into a vehicle seat of a motor vehicle, wherein the cardiogram signals are transmitted to an evaluation unit, wherein the evaluation unit determines the vital functions of the vehicle occupant from the cardiogram signals.

[0002] Furthermore, the present description relates to a motor vehicle comprising a vehicle seat and an evaluation unit. State of the art

[0003] In the field of mobility solutions development, autonomous driving, health and passenger safety are becoming increasingly important.

[0004] The ability to recognize the behavior of a driver and other vehicle occupants is already an integral part of modern motor vehicles. Examples include seat occupancy detection in combination with seatbelt sensors and driver fatigue detection.

[0005] Furthermore, there are efforts to record extended vital parameters of a driver. This makes it possible to determine the driver's fitness or health status. Information about the driver's health status can be used by driver assistance systems to initiate an emergency stop of the vehicle in emergency situations. This protects the driver and other occupants, as well as uninvolved potential accident victims, and helps prevent serious accidents.

[0006] Capacitive methods for measuring heart activity are known from the prior art; these can detect seat occupancy by monitoring changes in the capacitance of the seat heating electronics and chest movement induced by the heartbeat. However, these methods are very inaccurate. Other known, but equally inaccurate, methods use camera-, UWB-, or radar-based measurements.

[0007] Emergency medical detection, for example of a heart attack, is currently only possible via direct recording of heart muscle signals. This is usually done using electrodes in direct skin contact and is therefore unsuitable for convenient integration into a motor vehicle.

[0008] US Patent 8,706,204 B2 discloses a system for monitoring a passenger's heart rate. The system comprises a variety of different types of heart rate sensors arranged on a seat cushion or seat back. The heart rate sensors are designed as electrocardiogram sensors. US Patent 2009 / 326399 discloses a vehicle with a gradiometer for detecting magnetocardiogram signals.

[0009] US patent 10,210,409 B1 discloses a system for the contactless detection of an electrodermal potential, which is integrated into a motor vehicle. The electrodermal potential can be used to determine whether a vehicle occupant is awake or asleep. revelation

[0010] The present invention is based on the objective of providing a method for determining the vital functions of a vehicle occupant, which enables precise measurements and is easy to use without inconveniencing the vehicle occupant.

[0011] To solve the problem underlying the invention, a method for determining the vital functions of a vehicle occupant is proposed, wherein a sensor device integrated into a vehicle seat of a motor vehicle acquires measurement signals of a vehicle occupant without contact, wherein cardiogram signals are derived from the measurement signals, wherein an evaluation unit determines the vital functions of the vehicle occupant from the cardiogram signals, wherein it is further provided that the sensor device is a magnetic field sensor device, and that the cardiogram signals are magnetocardiogram signals.

[0012] The evaluation unit can draw conclusions about the fitness and health of the vehicle occupant from the magnetic resonance cardiogram (MRC) signals. In particular, the evaluation of the MRC signals makes it possible to detect medically relevant cardiac emergencies early and to bring about a safe stop before the vehicle occupant loses control of the vehicle and endangers themselves and others.

[0013] According to the invention, the magnetic field sensor device is a gradiometer with at least two magnetic field sensors arranged at mutually spaced positions, wherein the at least two magnetic field sensors measure a magnetic field at the spaced positions and generate the measurement signal, wherein the magnetocardiogram signal is further preferably determined as a difference signal of the measurement signals of the at least two magnetic field sensors.

[0014] The magnetic fields generated by the heart muscle have a strength in the range of 100 pT. These magnetic field strengths are significantly lower than typical ambient magnetic field strengths. For example, the Earth's magnetic field strength is approximately 50 µT, and the magnetic fields inside a vehicle range from 1 to 10 nT. By designing the magnetic field sensor device as a gradiometer with two magnetic field sensors positioned at a distance from each other, these interfering fields from the environment can be eliminated. For this purpose, the magnetic field is measured simultaneously with two magnetic field sensors. The interfering fields from the environment, which have the same field strength at both sensor positions, can be eliminated by calculating the difference between the measurement signals of the at least two magnetic field sensors.In the differential signal, only the magnetic field generated by the heart remains in the form of the magnetic cardiogram signal, since the magnetic field generated by the heart has a high gradient between the two positions of the magnetic field sensors.

[0015] The differential signal can be generated directly by the magnetic field sensor device. However, it is also possible for the differential signal to be generated in the evaluation unit, in which case the measurement signals from the magnetic field sensors are transmitted to the evaluation unit.

[0016] Preferably, the at least two magnetic field sensors are spaced 0.5 cm to 2 cm apart, more preferably 1 cm to 1.5 cm apart.

[0017] Investigations by the applicant have shown that biomagnetic fields, such as those generated by a heart, can be ideally measured at a distance of between 0.5 cm and 2 cm.

[0018] A further advantage may be that several magnetic field sensor devices are provided, and / or that the magnetic field sensor device in the vehicle seat is automatically positioned near the heart of the vehicle occupant.

[0019] Since there can be a very large variation in the size of potential vehicle occupants, it is advantageous to integrate several magnetic field sensors at different positions in the vehicle seat. Alternatively or additionally, the magnetic field sensor can be actively positioned within the vehicle seat so that, regardless of the occupant's size, it is always in close proximity to the heart. This ensures that a sufficiently strong magnetic resonance cardiogram (MRC) signal can be obtained.

[0020] It is further preferred that the magnetic field sensor device is arranged in a backrest of the vehicle seat.

[0021] According to the invention, the magnetic field sensors are nitrogen vacancy sensors, each nitrogen vacancy sensor preferably comprising a diamond, optical filters and photodetectors, and more preferably a microwave resonator and / or a light source, in particular a laser.

[0022] However, the microwave resonator and / or the light source may also be positioned opposite the magnetic field sensor device or the magnetic field sensors.

[0023] In principle, it is possible to use TMR, GMR, or Hall sensors, SQUID sensors, or vapor cell magnetometers to measure the magnetic fields required to determine the magnetocardiogram signals. However, such sensors generally lack sufficient sensitivity. While highly sensitive, superconducting SQUID sensors offer sufficient accuracy, they require active cooling with liquid nitrogen or helium and are therefore less suitable for use in a vehicle seat. Vapor cell magnetometers, although possessing the necessary sensitivity, have a limited dynamic range.

[0024] According to the invention, the magnetic field sensors are therefore nitrogen-vacancy sensors. Nitrogen-vacancy sensors are based on the measurement of a fluorescence spectrum of nitrogen centers in a diamond. The spectrum of a diamond with nitrogen vacancies shows fluorescence in the red wavelength range when optically excited. If microwave radiation is applied in addition to optical excitation, a dip in the fluorescence occurs at 2.88 GHz, since the electrons in this case are excited from the ms = 0 level of the 3A state to the ms = + / -1 level of the 3E state and from there recombine non-radiatively. With an external magnetic field, the ms levels split, the so-called Zeeman splitting, and when the fluorescence is plotted against the frequency of the microwave excitation, two dips appear in the fluorescence spectrum, the frequency separation of which is proportional to the magnetic field strength.The magnetic field sensitivity is defined by the minimum resolvable frequency shift and can reach up to 1 pT. Since the nitrogen vacancy center in a single-crystal diamond has four possible orientations within the crystal lattice, the presence of a directed magnetic field causes the nitrogen vacancy centers within the crystal to react differently to the external magnetic field depending on their position. In the maximum case, this can result in four corresponding pairs of fluorescence minima appearing in the spectrum, from whose shape and relative position the magnitude and direction of the magnetic field can be uniquely determined.

[0025] Furthermore, the structure and operation of a nitrogen void sensor are known to the expert.

[0026] A further advantage is that the magnetic cardiogram signals can be filtered by the evaluation unit using a high-pass and / or low-pass filter, and / or that the evaluation unit can determine a bias drift of the magnetic field sensors, in particular by averaging the magnetic cardiogram signals over a period of time that is greater than the heart rate.

[0027] Low-pass filtering eliminates noise components with frequencies significantly above the heart rate. Furthermore, bias drift can be subtracted from the high-pass and / or low-pass filtered signal, resulting in a clean magnetic resonance cardiogram (MCT) signal.

[0028] Furthermore, it is preferably provided that the evaluation unit determines vital parameters, preferably a heart rate, and / or a heart rate variability, and / or a duration and / or amplitude of ECG-equivalent signal changes, preferably P wave, QRS complex, T wave and corresponding combinations, from the magnetic cardiogram signals.

[0029] A further advantage is that the evaluation unit can determine the vital functions of the vehicle occupant based on the vital parameters, with the evaluation unit preferably making an assessment as to whether the vehicle occupant is tired or awake, under stress or relaxed, whether an acute or chronic anomaly of cardiac function is present or imminent, or whether underlying diseases with impairment of cardiac function are present.

[0030] Various methods can be used to determine the vital functions of a vehicle occupant based on vital parameters. One option is to use a threshold method based on a predefined table of corresponding normative values, which can be derived from clinical diagnostics. Furthermore, a data-driven evaluation or interpretation using a statistical classification method is possible. This can involve the use of a decision tree or a random forest method. Another possibility is to employ an evaluation using deep neural networks.

[0031] Preferably, further measures will be taken based on the assessment, including an emergency stop of the motor vehicle and / or making an emergency call and / or transmitting vital signs to medical personnel.

[0032] Additionally or alternatively, the driver can be actively warned that a medical problem has been detected. If the evaluation unit places an emergency call, vital signs, vital parameters, magnetic resonance cardiogram signals, or an assessment can be transmitted to medical personnel simultaneously with the call, thus enabling optimal treatment of the vehicle occupant without further delay through on-site ECG measurement.

[0033] Furthermore, additional information, such as the age or weight of the vehicle occupant, can be used to create the assessment. This additional information can be accessed via interfaces, such as a multimedia or infotainment system or an app.

[0034] Furthermore, it may be preferably provided that the evaluation unit sends the vital functions and / or the assessment to other vehicle equipment, in particular to an infotainment system, a driver assistance system or a comfort system.

[0035] For example, if vital signs and / or assessments are transmitted to a comfort system, a massage function, interior fragrance, or ambient lighting can be activated. Furthermore, vital signs and assessments can contribute to improved fatigue detection, thus enhancing the accuracy of break recommendations. This method can be combined with the evaluation of data from an interior camera for this purpose.

[0036] The assessment can be assigned a confidence value that reflects the statistical certainty of the classification result or the assessment.

[0037] An advantageous device is one designed for determining the vital functions of a vehicle occupant as described above, comprising a sensor device designed for installation in a vehicle seat, in particular a motor vehicle, and configured to detect measurement signals of a vehicle occupant, wherein the sensor device is designed as a magnetic field sensor device, and further comprising an evaluation unit connected to the magnetic field sensor device in a communication manner, which is designed to detect vital functions of a vehicle occupant from cardiogram signals obtained from the measurement signals, wherein the cardiogram signals are magnetocardiogram signals.

[0038] In an advantageous embodiment, it can be provided that the sensor device or the sensor device and the evaluation unit are arranged in the vehicle seat.

[0039] In manufacturing, it can clearly be advantageous to integrate the sensor device or the sensor device evaluation unit into the vehicle seat during its production.

[0040] The evaluation device can advantageously be implemented as a software module in a control unit or computer. This makes it possible to integrate the evaluation device into a control unit or computer already present in the vehicle, such as an infotainment computer or a central computer, which can be connected to the sensor device via discrete cables, a wired data bus, or a wireless interface. Another solution to the underlying problem involves providing a motor vehicle comprising a vehicle seat and an evaluation unit configured to carry out the aforementioned procedure.

[0041] All functions, features and designs explained in connection with the aforementioned procedure can also be transferred to the motor vehicle in a corresponding manner.

[0042] The description is explained in more detail below with reference to the attached figures.

[0043] They show Fig. 1 shows a vehicle seat with a magnetic field sensor device, Fig. 2 shows a magnetic field sensor device, and Fig. 3 shows a flowchart of the method.

[0044] A method 100 for determining the vital functions of a vehicle occupant 10 is explained in more detail below with reference to the figures.

[0045] According to procedure, a Fig. 1 The illustrated vehicle seat 11 of a motor vehicle (not shown in detail) is provided. A sensor device 13 is arranged in the vehicle seat 11, in particular in the backrest 12. The sensor device 13 is designed as a magnetic field sensor device 14 and detects measurement signals from the heart 15 of the vehicle occupant 10 ( Fig. 3 , step 110). The magnetic field sensor device 14 comprises two magnetic field sensors 16a, 16b arranged at positions spaced apart from each other. A first magnetic field sensor 16a is located closer to the heart 15 of the vehicle occupant 10 than a second magnetic field sensor 16b. The two magnetic field sensors 16a, 16b thus measure the magnetic field at the spaced-apart positions and each generates the measurement signals. The measurement signals determined by the magnetic field sensors 16a, 16b are transmitted wirelessly or via cable to an evaluation unit 19 ( Fig. 3 , step 120). By calculating the difference between the measurement signals of the two magnetic field sensors 16a, 16b, interfering fields, such as the Earth's natural magnetic field or magnetic fields occurring in motor vehicles, can be eliminated. The difference signal of the measurement signals is a magnetocardiogram signal. The evaluation unit 19 determines vital parameters from the magnetocardiogram signals ( Fig. 3 (Step 130). For this purpose, the magnetic resonance (MRR) signals are first filtered with a low-pass filter. Furthermore, the bias drift of the magnetic field sensors 16a and 16b is determined by averaging the MRR signals over a period longer than the heart rate. The bias drift of the magnetic field sensors 16a and 16b is subtracted from the MRR signals. From the vital parameters, which can be, for example, heart rate and / or heart rate variability, the evaluation unit 19 determines the vital functions of the vehicle occupant 10 and creates an assessment of the current condition or the psychological or physical state of the vehicle occupant (Step 140).This assessment may include, for example, determining whether the vehicle occupant 10 is tired or awake, under stress or relaxed, whether an acute or chronic cardiac abnormality is present or imminent, or whether underlying medical conditions affecting cardiac function are present. If the evaluation unit 19 determines that a vital function is impaired that affects the vehicle occupant 10's ability to drive, the evaluation unit 19 transmits the vital functions and / or the assessment to other vehicle systems, such as a driver assistance system (step 150).The driver assistance system is preferably designed to perform further measures depending on the information received from the evaluation unit regarding the condition of the vehicle occupant, for example, to automatically place an emergency call (eCall) to a control center, to bring the vehicle to a controlled stop, or to initiate other helpful or appropriate measures depending on the condition of the vehicle occupant (step 160). The two magnetic field sensors 16a, 16b are spaced 0.5 cm to 2 cm apart. The magnetic field sensor device 14 is designed as a gradiometer and is height-adjustable in the backrest 12 by means of a guide system 17, so that the magnetic field sensor device 14 can always be positioned near the heart 15 of the vehicle occupant 10.The two magnetic field sensors 16a, 16b are designed according to the invention as nitrogen vacancy sensors 18a, 18b and comprise, not shown in detail, a diamond, optical filters and photodetectors.

[0046] Fig. 2 shows a detailed view of the magnetic field sensor device 14 of the Fig. 1The magnetic field sensor device 14 comprises two magnetic field sensors 16a, 16b, which, according to the invention, are configured as nitrogen-vacancy sensors 18a, 18b. The two magnetic field sensors 16a, 16b are arranged at a distance of 0.5 cm to 2 cm from each other and each comprises a nitrogen-vacancy-doped diamond, optical filters, and photodetectors. The magnetic field sensor device 14 further comprises a laser 20 and a microwave resonator 21. The two nitrogen-vacancy sensors 18a, 18b are illuminated by the laser 20, with a fiber splitter 22 being provided in the beam path. Furthermore, microwave radiation is emitted onto the nitrogen-vacancy sensors 18a, 18b by the microwave resonator 21, with a microwave splitter 23 being arranged in the beam path.

Claims

1. Method (100) for determining the vital functions of a vehicle occupant (10), a sensor device (13) integrated in a vehicle seat (11) of a motor vehicle identifying measurement signals relating to a vehicle occupant (10), the measurement signals being used to identify cardiogram signals, an evaluation unit (19) using the cardiogram signals to identify vital functions of the vehicle occupant (10), the sensor device (13) being a magnetic field sensor device (14) and the cardiogram signals being magnetic cardiogram signals, the magnetic field sensor device (14) being a gradiometer having at least two magnetic field sensors (16a, 16b) arranged at spaced-apart positions, the at least two magnetic field sensors (16a, 16b) measuring a magnetic field at the spaced positions and generating the measurement signals, and the cardiogram signal being identified preferably as a difference signal relating to the measurement signals of the at least two magnetic field sensors (16a, 16b), characterized in that the magnetic field sensors (16a, 16b) are nitrogen-vacancy defect sensors (18a, 18b), each nitrogen-vacancy defect sensor (18a, 18b) preferably comprising a diamond, optical filters and photodetectors, and more preferably a microwave resonator (21) and / or a light source, in particular a laser (20).

2. Method (100) according to Claim 1, characterized in that there is provision for multiple magnetic field sensor devices (14), and / or in that the magnetic field sensor device (14) in the vehicle seat (11) is automatically positioned near the heart (15) of the vehicle occupant (10).

3. Method (100) according to either of the preceding claims, characterized in that the magnetic cardiogram signals are filtered by the evaluation unit (19) using a high-pass and / or low-pass filter, and / or in that the evaluation unit (19) identifies a bias drift of the magnetic field sensors (16a, 16b), in particular by averaging the magnetic cardiogram signals over a period greater than the heart rate.

4. Method (100) according to one of the preceding claims, characterized in that the evaluation unit (19) uses the magnetic cardiogram signals to identify vital parameters, preferably a heart rate, and / or a heart rate variability, and / or a duration and / or amplitude of ECG-equivalent signal changes, preferably P-wave, QRS complex, T-wave and relevant combinations.

5. Method (100) according to Claim 4, characterized in that the evaluation unit (19) takes the vital parameters as a basis for determining the vital functions of the vehicle occupant (10), preferably by means of a statistical classification method, the evaluation unit (19) more preferably producing an assessment of whether the vehicle occupant (10) is tired or awake, is under stress or is relaxed, whether an acute or chronic abnormality in cardiac function exists or is imminent, or whether underlying diseases that impair cardiac function exist.

6. Method (100) according to Claim 5, characterized in that the assessment is taken as a basis for taking further measures, the further measures including an emergency stop by the motor vehicle and / or placing an emergency call and / or transmitting the vital functions to medical personnel.

7. Method (100) according to one of the preceding claims, characterized in that the evaluation unit (19) sends the vital functions and / or the assessment to other motor vehicle apparatuses, in particular to an infotainment system, to a driver assistance system or to a comfort system.

8. Apparatus configured to determine the vital functions of a vehicle occupant (10) according to one of Claims 1 to 7, comprising a sensor device (13) designed for installation in a vehicle seat (11) of a vehicle, in particular a motor vehicle, and configured to identify measurement signals relating to a vehicle occupant (10), the sensor device (13) being a magnetic field sensor device (14), and further comprising an evaluation unit (19) designed to use cardiogram signals obtained from the measurement signals to identify vital functions of a vehicle occupant (10), the cardiogram signals being magnetic cardiogram signals and the magnetic field sensor device (14) being a gradiometer having at least two magnetic field sensors (16a, 16b) arranged at spaced-apart positions, the at least two magnetic field sensors (16a, 16b) being designed to measure a magnetic field at the spaced positions and to generate the measurement signals, and the evaluation unit (19) being configured to identify the cardiogram signal preferably as a difference signal relating to the measurement signals of the at least two magnetic field sensors (16a, 16b), characterized in that the magnetic field sensors (16a, 16b) are nitrogen-vacancy defect sensors (18a, 18b), each nitrogen-vacancy defect sensor (18a, 18b) preferably comprising a diamond, optical filters and photodetectors, and more preferably a microwave resonator (21) and / or a light source, in particular a laser (20).

9. Apparatus according to Claim 8, characterized in that the sensor device (13) or the sensor device (13) and the evaluation unit (19) are arranged in the vehicle seat.

10. Motor vehicle comprising the vehicle seat (11) and the apparatus according to Claim 9.