Method for determining vital parameter of occupant of motor vehicle, and motor vehicle

Abstract

The invention relates to a method for determining a vital parameter of an occupant (16) of a motor vehicle (10). The invention also relates to a motor vehicle (10) having a control unit (14) provided for carrying out the method. According to the invention, a vital parameter of the occupant (16) is determined on the basis of calculated phase information of an echo signal assigned to the occupant of an impulse response of the emitted UWB pulse. According to the invention, a vital parameter can be determined in a particularly reliable manner on the basis of the phase information of the echo signal, since the phase information is less susceptible to motion artifacts.

Description

[0001] The invention relates to a method for determining a vital parameter of an occupant of a motor vehicle. The invention also relates to a motor vehicle having a UWB system and a control unit which is provided for carrying out the method.

[0002] Modern cars have various safety and emergency assistance systems that perform (emergency) interventions in the driving operation based on the information acquired about the vehicle driver's condition. If the driver suffers from a health emergency, for example, this is detected by the corresponding sensors of the assistance system and an autonomous emergency intervention is performed on the driving operation of the motor vehicle in order to bring the vehicle to an emergency stop on the driving lane or on the emergency lane.

[0003] The problem here is the reliable detection of the driver's emergency situation. An erroneously determined emergency situation and the resulting intervention in the driving operation are just as undesirable as an undetermined emergency situation that actually occurred. Therefore, reliable emergency situation detection in the vehicle is required in order to be able to distinguish between an actual health emergency situation of the driver and a non-critical situation.

[0004] In medicine, the health status of a person is derived from the knowledge of his vital parameters. Vital parameters are quantities that reflect the basic functions of the human body and can be measured in order to check the vital functions. Vital parameters include, for example, heart rate, blood pressure, body temperature and / or respiratory rate.

[0005] Radar-based detection systems are known for determining the vital parameters of a vehicle driver, which detect and monitor the movement of areas of the driver's body over time. In this case, a radar signal is emitted at periodic intervals toward the driver and its corresponding impulse response is analyzed based on the detected amplitude changes. However, it has been shown that the analysis of the amplitude changes contains many motion artifacts that impair the reliable inference of the driver's vital parameters.

[0006] The object of the present invention is therefore to develop a method for more reliably determining a vital parameter of an occupant of a motor vehicle.

[0007] The object of the invention is achieved by a method for determining a vital parameter of an occupant of a motor vehicle and a motor vehicle according to the independent claims. Preferred developments are the subject of the dependent claims.

[0008] One aspect relates to a method for determining a vital parameter of an occupant of a motor vehicle. In this case, a first ultra-wideband (UWB) pulse is transmitted by a UWB transceiver, and a first pulse response is received by the UWB transceiver. The (first) UWB pulse preferably has a pulse width in the nanosecond range, in particular a pulse width of less than one nanosecond (1 ns), particularly preferably a pulse width of 0.2 ns. The (first) pulse response is preferably received in a time period of 25 ns to 65 ns, particularly preferably a time period of 50 ns. In other words, the (first) pulse response is preferably received in a time period corresponding to an effective range of up to 10 m. The UWB transceiver is particularly designed to transmit and receive signals in a very large frequency range, in particular in a frequency range of 3.1 to 10.6 GHz, preferably in a frequency range of 3.5 to 9 GHz, particularly preferably in a frequency range of 6 GHz to 8.5 GHz. The transmission power of the UWB pulse is relatively low here. The UWB transceiver preferably includes an antenna configured to transmit and receive UWB signals.

[0009] The bandwidth of the UWB transceiver is at least 500 MHz, and the UWB transceiver is preferably designed to send signals with a transmission power of 0.5 mW / -41.3 dBm / MHz. In addition, the UWB transceiver is preferably designed in accordance with the standard IEEE 802.15.4 (especially the section on the UWB PHY layer) and preferably in accordance with the standard IEEE 802.15.4z. Since the signal is dispersed over such a large frequency range, the UWB signal only minimally interferes with other radio signals.

[0010] Since UWB pulses are highly localized in time, information about the environment, and in particular about changes occurring in the environment, can be extracted from the received impulse response generated by the transmitted UWB pulses. This is based on the influence of the environment on the geometrically defined paths of the UWB pulses, such as refraction, diffraction, reflection, or attenuation. Thus, it is obvious that the travel times of the signals or signal packets of the UWB pulses along different propagation paths are different and change depending on whether there are objects in or near the propagation paths. The pulse shape of the signals or signal packets of the UWB pulses is also affected depending on whether there are objects or people on or near the propagation paths. Thus, the impulse response depicts a plurality of time-resolved echo signals, which echo signals are manifested in the impulse response according to the distances of these objects and / or people relative to the transceiver. The farther an object is from the UWB transceiver, the later the UWB transceiver receives the echo signal assigned to that object. In this way, the effective range of the UWB transceiver can be limited by interrupting the reception of the impulse response after a time corresponding to the desired effective range and / or by transmitting new UWB pulses. During the transmission of UWB pulses by the transceiver, the transceiver used for transmission cannot receive the impulse response.

[0011] In other words, the (first) impulse response can be regarded as an array of echo signals with amplitudes (x0, x1, … xN) and distances (d0, d1, …, dN relative to the UWB transceiver, where d0 < d1 < … < dN). The running indices (0, 1, … N) of the different echo signals are also referred to as radar bin indices. The array of echo signals is also referred to as a "fast time" radar frame.

[0012] In the method according to the invention, the first echo signal of the first impulse response is assigned to the occupant based on the first amplitude information of the first impulse response. In other words, the radar bin index is determined based on the amplitude information of the array of echo signals corresponding to the occupant. For example, the (first) echo signal corresponding to the occupant is determined by comparing the amplitude shape stored in the memory characterizing the occupant with the amplitude shape of the received impulse response. Preferably, a plurality of echo signals of the impulse response are determined and the echo signal with the maximum amplitude among them is assigned to the occupant. In other words, a peak is searched for in the amplitudes of the "fast time" radar frame and the echo signal corresponding to this peak is assigned to the occupant. This is a particularly simple and computationally less intensive method.

[0013] After the first echo signal is assigned to an occupant, first phase information of the first echo signal is calculated and life parameters of the occupant are determined based on the first phase information. The life functions of the occupant's body, in particular the breathing and heartbeat of the occupant, cause periodic body movements, including chest movements, in particular chest movements in the micro-chest region. This body movement is very reliably correlated with the calculated phase information of the (first) echo signal assigned to the occupant. In other words, the smallest movement of the occupant's chest changes the calculated phase information in the (first) echo signal. Therefore, such movement can be reliably deduced from the calculated phase information and the life parameters of the occupant can be reliably estimated. This is also because the movement artifacts that occur when analyzing the phase information to determine the life parameters are much less than those in the conventional radar-based detection methods. In this regard, the life parameters can be reliably determined according to the present invention.

[0014] In a preferred design of the present invention, it is provided that a second UWB pulse is also transmitted by the UWB transceiver and a second pulse response is received. The main difference between the second pulse response and the first pulse response here is that the second pulse response is acquired at different time points, preferably at a later periodic time point. It is also preferably provided that the second echo signal of the second pulse response is assigned to the occupant based on the second amplitude information of the second pulse response and the second phase information of the second echo signal is calculated. Here, the life parameters of the occupant are also determined based on the second phase information. Particularly preferably, the life parameters of the occupant are estimated based on the phase change between the first and second echo signals. The chest movement of the occupant caused by breathing and heartbeat, including minute chest movements, has a particularly high correlation with the phase change over time. Therefore, the occupant movement caused by the life functions can be detected particularly sensitively based on the calculated phase change, so that the life parameters of the occupant can be determined more reliably.

[0015] Similar to the first pulse response, the second pulse response can also be described as an echo signal array as described above, which has amplitudes (x0, x1, … xN), distances (d0, d1, …, dN relative to the UWB transceiver, where d0 < d1 < … < dN), and running indices (0, 1, … N). However, since this array corresponds to a (periodic) time-shifted “fast time” radar frame, it is also called a “slow time” radar frame. Since the radar bin index corresponding to the occupant has been determined from the “fast time” radar frame, the radar bin index can also be used in the “slow time” radar frame to determine the corresponding second echo signal corresponding to (or assigned to) the occupant and calculate the corresponding second phase information of the second echo signal. Since it is not necessary to re-determine the radar bin index, the required computational power consumption is reduced.

[0016] In another preferred design of the present invention, it is provided that the vital parameters are also determined based on another echo signal adjacent to the echo signal. In other words, another radar Bin index is used to determine the vital parameters. The echo signal usually depicts the restricted expansion of the chest within a few centimeters (e.g., 5 cm). If the occupant or his chest moves due to deep inhalation or exhalation or due to a change in sitting posture, the following situation may occur, wherein the radar Bin index first determined has been properly determined according to the first pulse response, but for the pulse response at different time points, for example, in the "slow time" radar frame of the second UWB pulse, the radar Bin index may not be assigned to the occupant. Therefore, the radar Bin index to be assigned to the occupant may "migrate" between the pulse responses as the chest moves or may also depend on the chest depth of the corresponding occupant. In principle, 5 to 8 echo signals can be used to cover the expansion of about 30 cm of the occupant's chest. Advantageously, therefore, the assignment of the radar bin index assigned to the occupant can be realized more reliably when the echo signals adjacent to the first and / or second echo signals are additionally taken into account, so that the vital parameters of the occupant can be determined more reliably. Preferably, in addition to the assigned echo signals, directly adjacent echo signals (a total of 3 echo signals), in particular two directly adjacent echo signals in each case (a total of 5 echo signals), particularly preferably three directly adjacent echo signals in each case (a total of 7 echo signals) are also taken into account to determine the vital parameters.

[0017] It is also preferred that further phase information of the further echo signal is calculated, and the vital parameters of the occupant are determined based on the further phase information. It is particularly preferred that the correlation between adjacent echo signals is calculated by means of a correlation coefficient, and the phase information of the (adjacent) echo signals corresponding to the occupant is used to determine the vital parameters. This further improves the reliability of determining the vital parameters.

[0018] In another preferred design of the present invention, it is provided that the echo signal is converted into a digital echo signal pair by an analog-to-digital converter pair, and the phase information is calculated from the digital echo signal pair. Since the electromagnetic oscillation signal consists of a real part and an imaginary part, the analog-to-digital converter always only takes into account a part, namely the real part. However, in order to prevent the phase information in the imaginary part from being lost, an analog-to-digital converter pair with a phase shift of 90° is preferably used. The so-called "In-phase" and "Quadrature-Phase" (IQ) data (down-conversion) are generated by the analog-to-digital converter pair, which can determine the phase information from the angular relationship between the I vector and the Q vector of the IQ data. In other words, the real part and the imaginary part of the electromagnetic oscillation signal can be taken into account, and the phase information contained in the imaginary part can also be calculated.

[0019] In another preferred design of the present invention, it is provided that the position of the occupant is estimated based on the seat setting of the occupant and / or based on the assigned echo signal. This enables a simple rough estimate or pre-estimation of the position of the occupant without a large computational effort. A rough understanding of the occupant's position improves the assignment of the one or more echo signals to the occupant. Preferably, static objects are filtered out by pre-measurement in the absence of occupants. Furthermore, preferably, the seat setting of the occupant's seat is determined, for example, before the occupant enters the motor vehicle and / or after the occupant leaves the motor vehicle, and the seat setting is stored in a storage unit of the motor vehicle. The stored seat setting can then be conveniently used to pre-estimate the position of the occupant.

[0020] In addition, preferably, the beam angle of the UWB transceiver is adjusted to the estimated position of the occupant by digital beamforming. When the UWB transceiver includes a plurality of (sub) units (antennas or sub-antennas) configured to transmit and receive UWB signals, these (sub) units transmit UWB pulses with a time shift or phase shift relative to each other, and the beam angle of the UWB transceiver can be preset in the case of digital beamforming. Due to the interference effect of the moving UWB pulses, a propagating wavefront with a directional direction, i.e., a beam angle, is generated. Therefore, by digital beamforming, the beam angle of the UWB transceiver can be advantageously adjusted according to the position of the occupant, so as to optimally determine the vital parameters according to the position of the occupant, thereby further improving reliability. However, in different examples, the vital parameters of different occupants of the vehicle can also be determined by aligning the transmission of the UWB pulses and the reception of the pulse response to the positions of the different occupants by digital beamforming. For example, the vital parameters of two occupants (or more occupants) are alternately determined by corresponding digital beamforming. Particularly preferably, the beam angle can also be optimized in advance as a function of the occupant by first estimating the position of the occupant (distance and angle relative to the UWB transceiver) from the echo signals assigned to the occupant. After the beam angle of the UWB transceiver is adjusted accordingly as a function of the determined occupant position, the above method steps are performed in order to determine the vital parameters of the occupant using the UWB transceiver. The prior optimization of the beam angle as a function of the occupant position thus increases the reliability of the determined vital parameters.

[0021] In another preferred design of the present invention, it is provided that, when determining the vital parameters, a bandpass filter is used to determine the breathing information and / or heartbeat information of the occupant from the phase information. This is based on the following understanding, that is, the frequencies of the breathing and heartbeat of the (human) body are significantly different, that is, the frequency of the occupant's heartbeat is significantly higher than the breathing frequency. The breathing information is filtered out by correspondingly using a low-pass filter with a suitable cut-off frequency and the heartbeat information is filtered out by correspondingly using a high-pass filter with a suitable cut-off frequency. This information is then used as the basis for determining the breathing rate and breathing phases, such as inspiration and exhalation and breath holding and / or heart rate and heartbeat phases. Different vital parameters can thus be advantageously and easily determined from the phase information.

[0022] In another preferred embodiment of the present invention, it is provided that the vital parameters of another occupant are determined by another UWB transceiver that is configured to transmit UWB pulses and receive corresponding pulse responses, wherein a plurality of UWB transceivers are spaced apart horizontally. The horizontal distance is necessary in order to be able to distinguish the pulse responses of two passengers. UWB transceivers spaced apart along the direction of travel of the vehicle, for example, enable differentiation of occupants along the direction of travel, while UWB transceivers spaced apart transversely to the direction of travel enable differentiation of occupants transversely to the direction of travel. Particularly preferably, both UWB transceivers spaced apart along the direction of travel and UWB transceivers spaced apart transversely to the direction of travel are provided in order to enable differentiation of occupants in all horizontal directions (along the direction of travel and transversely to the direction of travel).

[0023] Although always mention one or more passengers, passengers do not necessarily have to refer to only adult passengers. In addition, the vital parameters of children, babies and / or animals can also be determined here.

[0024] Further advantageous embodiments of the invention result from the remaining features mentioned in the dependent claims.

[0025] The various embodiments of the invention mentioned in this application can advantageously be combined with one another unless otherwise stated individually.

[0026] The individual method steps of the method according to the invention are also preferably designed as one or more processes, which are run on one or more processors of one or more electronic computing devices and are generated when one or more computer programs are executed. The computing device is preferably designed to cooperate with other components, in particular a UWB transceiver, in order to realize the functions described herein.

[0027] The instructions of the computer program are also preferably stored in a memory, such as a RAM element. However, the computer program can also be stored in a non-volatile storage medium, such as a CD-ROM, a flash memory or a similar non-volatile storage medium.

[0028] It is also obvious to a person skilled in the art that the functions of multiple computers (data processing devices) can be combined or can be combined in a single device, or that the functions of a specific data processing device can be distributed on multiple devices in order to perform multiple steps of the method according to the invention, without deviating from the method according to the invention.

[0029] A further aspect of the invention relates to a computer program comprising commands which, when executed by a computer, cause the computer to carry out the method according to the invention, in particular a method for determining vital parameters of an occupant of a motor vehicle, wherein the computer is, for example, a control unit of a motor vehicle having a UWB system having a UWB transceiver configured to transmit and receive UWB pulses.

[0030] A further aspect relates to a motor vehicle. The motor vehicle comprises a UWB system having a UWB transceiver configured to transmit and receive UWB pulses; the motor vehicle further comprises a control unit connected to the UWB system, the control unit being configured to implement the above method. The advantageous effects and optional features described within the scope of the method can be similarly applied to the motor vehicle. Therefore, a repeated description is omitted.

[0031] In a preferred embodiment, the UWB system is arranged in the upper region of the windshield of the motor vehicle or in a rearview mirror, in particular a central rearview mirror. The above-mentioned region of the motor vehicle is a favorable location for determining vital parameters, because the area between the transceiver and the occupant is usually free of interfering objects. The UWB system preferably comprises two horizontally spaced UWB transceivers configured for transmitting and receiving UWB pulses, both of which are arranged in the above-mentioned locations.

[0032] In another preferred embodiment, the motor vehicle includes an electronic seat adjustment device. The position of the occupant can be advantageously inferred from the setting of the electronic seat adjustment device. For example, the body posture of the occupant (lying or sitting) can be determined and the beam angle of the UWB transceiver can be adjusted based on this information in order to increase the reliability of the determined vital parameters.

[0033] The present invention is described below in the following embodiments according to the accompanying drawings. In the accompanying drawings:

[0034] Figure 1 A schematic diagram showing a method according to one embodiment of the present invention; and

[0035] Figure 2 A schematic diagram of a motor vehicle according to the present invention is shown according to one specific embodiment.

[0036] according to Figure 1 and Figure 2The method according to the invention and the motor vehicle according to the invention are explained in more detail in the schematic diagram of FIG. According to the invention, vital parameters of the occupants 16 , 18 of the motor vehicle 10 can be determined in a reliable manner.

[0037] In a first method step 50, a UWB transceiver of the UWB system 12 (see Figure 2 ) transmits a first UWB pulse which is highly localized in time in the direction of an occupant 16 of the motor vehicle 10 .

[0038] The first impulse response is then received by the UWB transceiver in a second method step 52. Since UWB pulses are highly localized in time, information about the environment and changes occurring in the environment can be determined from the received impulse response resulting from the transmitted UWB pulse. For example, echo signals are contained in the impulse response, which can be distinguished from one another based on amplitude information and can be assigned to objects, surfaces, persons or the like.

[0039] In a third method step 54, the first echo signal of the first impulse response is assigned to the occupant 16 based on the first amplitude information of the first impulse response. From the determined plurality of echo signals of the first impulse response, the echo signal with the largest amplitude is assigned to the occupant 16. The individual echo signals are consecutively numbered by radar bin indices, and the radar bin indices of the echo signals assigned to the occupant 16 are acquired.

[0040] In a fourth method step 56, the UWB transceiver of UWB system 12 transmits a second UWB pulse that is highly localized in time in the direction of occupant 16 of motor vehicle 10. The second UWB pulse corresponds to the first UWB pulse, but only at a later (periodically) point in time.

[0041] In a fifth step 58, a second impulse response is received by the UWB transceiver in a similar manner to the second method step 52. The second impulse response corresponds substantially to the first impulse response, but at a later time. Changes in the environment can be inferred based on the time difference between the two UWB impulses and by comparing the first impulse response and the second impulse response.

[0042] In the sixth method step 60, the second echo signal of the second pulse response is assigned to the occupant 16 based on the second amplitude information of the second pulse response. This can be done similarly to the third method step 54 using a plurality of echo signals of the second pulse response. However, preferably, in the sixth method step, the radar Bin index known from the third method step and assigned to the occupant 16 is used to assign the second echo signal to the occupant 16 (indicated by the dashed arrow A). It is assumed that the (sitting) posture of the occupant 16 does not change significantly between the two UWB pulses, so as to reduce the computational effort required to determine the radar Bin index of the occupant 16 according to the third method step 54.

[0043] In a seventh method step 62, the phase information of the first and second echo signals is calculated. For this purpose, the UWB transceiver comprises an analog-to-digital converter pair, the analog-to-digital converters of which are phase-shifted by 90°. As a result, the oscillation information of the first and second echo signals is converted into two digital echo signals (IQ data), respectively. The first and second phase information of the first and second echo signals is then calculated from the IQ data of the first and second echo signals.

[0044] In an eighth method step 64, vital parameters of the occupant 16 are determined based on the first and second phase information. To this end, phase changes are calculated from the first and second phase information and the body movements of the occupant are inferred therefrom. In the example shown, the UWB transceiver is aimed at the chest of the occupant in order to distinguish the movements of the chest. Due to the vital functions of the occupant's body, the chest moves back and forth at periodic intervals. It is therefore possible to estimate the vital parameters of the occupant based on the phase information by knowing the position of the chest at different points in time. Heart rate information and breathing phase are determined from the acquired chest movement by means of a suitable bandpass filter. It is obvious here that the described method can be repeated indefinitely in order to continuously monitor the occupant 16 (or the occupant's chest) based on the calculated vital parameters.

[0045] exist Figure 2 A UWB system 12 and a control unit 14 configured to implement the method are shown. The UWB system and the control unit are arranged in a central rearview mirror of the motor vehicle 10. In the example shown, the motor vehicle 10 according to the invention comprises a UWB system 12 having two UWB transceivers configured to transmit and receive UWB pulses, the two UWB transceivers being spaced apart transversely to the direction of travel of the motor vehicle 10. This arrangement enables two occupants 16 and 18 located in the motor vehicle 10 spaced apart from each other transversely to the direction of travel to be monitored simultaneously by the method proposed here. To this end, the two UWB transceivers are respectively aimed at one of the two occupants 16, 18, and the method for determining a vital parameter is implemented separately for each occupant 16, 18 (see Figure 2 The beam angle of the UWB transceiver can be realized, for example, by digital beamforming. It is thus advantageously possible to reliably determine the vital parameters of two occupants 16, 18 of the motor vehicle 10. Obviously, the vital parameters of more than two occupants can also be determined and monitored in a similar manner.

[0046] Reference numerals list

[0047] 10 Motor Vehicles

[0048] 12UWB system

[0049] 14Control Unit

[0050] 16 crew members

[0051] 18 Additional Crew

[0052] 50First Method Steps

[0053] 52 Second method step

[0054] 54Third Method Step

[0055] 56 Fourth method step

[0056] 58 Fifth Method Step

[0057] 60 Sixth Method Step

[0058] 62Seventh Method Step

[0059] 64 Eighth Method Step

Claims

1. A method for determining a vital parameter of an occupant (16) of a motor vehicle (10), comprising the following steps: transmitting, by the UWB transceiver, a first UWB pulse and receiving a first pulse response, assigning a first echo signal of the first impulse response to the occupant based on first amplitude information of the first impulse response (16), calculating first phase information of the first echo signal, and A vital parameter of the occupant (16) is determined based on the first phase information.

2. The method according to claim 1 further comprises the following steps: transmitting, by the UWB transceiver, a second UWB pulse and receiving a second pulse response, assigning a second echo signal of the second impulse response to the occupant based on second amplitude information of the second impulse response (16), calculating second phase information of the second echo signal, and A vital parameter of the occupant (16) is also determined based on the second phase information.

3. The method according to claim 1 or 2, wherein: The vital parameter is also determined based on further echo signals adjacent to the echo signal.

4. The method according to claim 3, wherein: Further phase information of the further echo signal is calculated and a vital parameter of the occupant (16) is determined based on the further phase information.

5. A method according to any one of the preceding claims, wherein: The echo signals are converted into a pair of digital echo signals by a pair of analog-to-digital converters, and phase information is calculated from the pair of digital echo signals.

6. A method according to any one of the preceding claims, wherein: The position of the occupant (16) is estimated based on the occupant's seat setting and / or based on the assigned echo signal.

7. The method according to claim 6, wherein: The beam angle of the UWB transceiver is adjusted to the estimated position of the occupant (16) by digital beamforming.

8. A method according to any one of the preceding claims, wherein: When determining the vital parameters, a bandpass filter is used to determine the breathing information and / or heartbeat information of the occupant (16) from the phase information.

9. A method according to any one of the preceding claims, wherein: Vital parameters of additional occupants (18) are determined by additional UWB transceivers configured to transmit UWB pulses and receive corresponding pulse responses, wherein a plurality of UWB transceivers are horizontally spaced apart.

10. A motor vehicle (10) comprising: A UWB system (12) having a UWB transceiver configured to transmit and receive UWB pulses; and A control unit (14) connected to the UWB system, the control unit being configured to: The method according to any one of claims 1 to 9 is implemented.

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