System and method for detecting vital signs

Abstract

To provide a system and method for detecting a vital sign.SOLUTION: A method for detecting a vital sign comprises: transmitting a first radio frequency signal through a first radar to receive a first radar signal corresponding to the first radio frequency signal; performing in-phase quadrature demodulation to the first radar signal to acquire first received in-phase component and a first received quadrature component; performing a first convolution operation to the first received in-phase component and a first symbol and performing first product-sum operation to a first result of the first convolution operation to acquire a first cumulative value; performing second convolution operation to the first received in-phase component and the first symbol and performing second product-sum calculation to a second result of the second convolution operation to acquire a second cumulative value; and creating a vital sign on the basis of the first and second cumulative values.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a detection system and a detection method, and more particularly to a detection system and a detection method for vital signs. [Background technology]

[0002] Vital sign detection technology can be used in fields such as healthcare, driving monitoring, and home care. Conventional vital sign monitoring systems can measure the subject's vital signs through wearable devices, but the wearable devices may cause discomfort to the subject. To reduce the discomfort to the subject, current monitoring systems have been improved to measure the subject's vital signs using radio frequency signals. However, vital signs measured using radio frequency signals may be affected by factors such as local oscillator (LO) failure, in-phase and quadrature (IQ) deviation, IQ gain mismatch or frequency mismatch, resulting in distortion. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention provides a vital signs detection system and method that is capable of detecting the vital signs of a subject within a motorized vehicle in a non-contact manner. [Means for solving the problem]

[0004] The vital signs detection system applied to a motor vehicle of the present invention includes a first radar and a server, the server being communicatively connected to the first radar and configured to transmit a first radio frequency signal via the first radar and receive a first radar signal corresponding to the first radio frequency signal, the first radio frequency signal including a first outgoing in-phase component and a first outgoing quadrature component; perform in-phase and quadrature demodulation on the first radar signal to obtain a first received in-phase component and a first received quadrature component; perform a first convolution operation on a first symbol corresponding to the first received in-phase component and the first outgoing quadrature component, and perform a first product-and-sum operation on a first result of the first convolution operation to obtain a first accumulation value; The radar is configured to perform the following: performing a second convolution operation on a first symbol corresponding to the first received quadrature component and the first transmitted quadrature component, and performing a second multiply-and-accumulate operation on a second result of the second convolution operation to obtain a second accumulated value; generating a first processed signal based on the first accumulated value and the second accumulated value; generating a vital sign corresponding to the first radar based on the first processed signal, and outputting the vital sign, wherein a first symbol of the first transmitted quadrature component is orthogonal to an transmitted in-phase symbol of the first transmitted in-phase component, and the first symbol is a symbol with an average value of zero.

[0005] In one embodiment of the present invention, the detection system further includes a second radar, the second radar being communicatively connected to a server, the server being further configured to: transmit a second radio frequency signal via the second radar and receive a second radar signal corresponding to the second radio frequency signal; perform pre-processing on the second radar signal to obtain a second processed signal; and generate a vital sign based on the first processed signal and the second processed signal.

[0006] In one embodiment of the present invention, the server is further configured to, in response to a first power component of the first processed signal being greater than a threshold and a second power component of the second processed signal being equal to or less than a threshold, subtract the second processed signal from the first processed signal to obtain a vital sign corresponding to the first radar.

[0007] In one embodiment of the present invention, the server is further configured to: be communicatively connected to the motorized vehicle to obtain dashboard information, and based on the dashboard information, query the lookup table to obtain a vibration frequency; and process the first processed signal based on the vibration frequency to obtain a vital sign.

[0008] In one embodiment of the invention, the dashboard information includes engine RPM.

[0009] In one embodiment of the present invention, a first symbol of a first transmitted quadrature component of the first radio frequency signal is mutually orthogonal to a second symbol of a second transmitted quadrature component of a second radio frequency signal.

[0010] In one embodiment of the present invention, the first radio frequency signal and the second radio frequency signal are orthogonal frequency division multiplexed signals.

[0011] In one embodiment of the present invention, the server is further configured to perform, based on the first result, a first difference calculation to obtain a first difference; and calculate a ratio between the first difference and a second accumulated value to generate a first processed signal.

[0012] In one embodiment of the invention, the server is further configured to perform low pass filtering on the first radar signal to obtain a first processed signal.

[0013] In one embodiment of the invention, the vital signs include a time-varying signal indicative of a change in position.

[0014] A vital sign detection method applicable to a motor vehicle of the present invention includes transmitting a first radio frequency signal via a first radar, and receiving a first radar signal corresponding to the first radio frequency signal, the first radio frequency signal including a first transmitted in-phase component and a first transmitted quadrature component; performing in-phase and quadrature demodulation on the first radar signal to obtain a first received in-phase component and a first received quadrature component; performing a first convolution operation on a first symbol corresponding to the first received in-phase component and the first transmitted quadrature component, and performing a first product-sum operation on a first result of the first convolution operation to obtain a first accumulation value. performing a second convolution operation on a first symbol corresponding to the first received quadrature component and the first transmitted quadrature component, and performing a second product-sum operation on a second result of the second convolution operation to obtain a second accumulated value; generating a first processed signal based on the first accumulated value and the second accumulated value; generating a vital sign corresponding to the first radar based on the first processed signal, and outputting the vital sign, wherein a first symbol of the first transmitted quadrature component is orthogonal to an transmitted in-phase symbol of the first transmitted in-phase component, and the first symbol is a symbol with an average value of zero.

[0015] In one embodiment of the present invention, the above detection method further includes: transmitting a second radio frequency signal via a second radar and receiving a second radar signal corresponding to the second radio frequency signal; performing pre-processing on the second radar signal to obtain a second processed signal; and generating vital signs based on the first processed signal and the second processed signal.

[0016] In one embodiment of the present invention, the detection method further includes, in response to a first power component of the first processed signal being greater than a threshold and a second power component of the second processed signal being equal to or less than the threshold, subtracting the second processed signal from the first processed signal to obtain a vital sign corresponding to the first radar.

[0017] In one embodiment of the present invention, the above detection method further includes obtaining dashboard information from the motorized vehicle, and querying a lookup table based on the dashboard information to obtain a vibration frequency; and processing the first processed signal based on the vibration frequency to obtain a vital sign.

[0018] In one embodiment of the invention, the dashboard information includes engine RPM.

[0019] In one embodiment of the present invention, a first symbol of a first transmitted quadrature component of the first radio frequency signal is mutually orthogonal to a second symbol of a second transmitted quadrature component of a second radio frequency signal.

[0020] In one embodiment of the present invention, the first radio frequency signal and the second radio frequency signal are orthogonal frequency division multiplexed signals.

[0021] In one embodiment of the present invention, the step of generating a first processed signal based on the first accumulated value and the second accumulated value includes: performing a first difference calculation based on the first result to obtain a first difference; and calculating a ratio between the first difference and the second accumulated value to generate the first processed signal.

[0022] In one embodiment of the present invention, the detection method further includes performing low-pass filtering on the first radar signal to obtain a first processed signal.

[0023] In one embodiment of the invention, the vital signs include a time-varying signal indicative of a change in position. Effect of the Invention

[0024] Based on the above, the detection system of the present invention can improve the accuracy of vital signs detected in radar unstable environments. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic diagram of a vital signs detection system according to an embodiment of the present invention; [Figure 2A] 1 is a schematic diagram of a motorized vehicle according to one embodiment of the present invention; [Figure 2B] 1 is a schematic diagram of a motorized vehicle according to one embodiment of the present invention; [Diagram 3] FIG. 2 is a flow diagram of a method for detecting vital signs according to an embodiment of the present invention. [Figure 4] 1 is a circuit diagram of a transmission circuit of a radar according to an embodiment of the present invention. [Diagram 5] 1 is a circuit diagram of a receiving circuit of a radar according to an embodiment of the present invention. [Figure 6] FIG. 2 is a flow diagram of a method for detecting vital signs according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In order to facilitate understanding of the present invention, the following examples are provided to illustrate embodiments in which the present invention can be practiced. Furthermore, wherever possible, elements / components / steps having the same reference numbers in the drawings and embodiments represent the same or similar parts.

[0027] 1 is a schematic diagram of a vital signs detection system 10 according to an embodiment of the present invention. The detection system 10 may include a server 100 and i radars communicatively connected to the server 100, where i is any positive integer. In the following description, it is assumed that N is 4, and the i radars may include radar 210, radar 220, radar 230, and radar 240. The radars 210, radar 220, radar 230, or radar 240 may have the same or similar structure or function. The detection system 10 may be used to detect vital signs of a target, where the vital signs include, but are not limited to, respiration or heart rate.

[0028] The server 100 may include a processor 110, a storage medium 120, and a transceiver 130. The processor 110 may be, for example, a central processing unit (CPU) or other programmable general-purpose or special-purpose micro control unit (MCU), microprocessor, digital signal processor (DSP), programmable controller, application specific integrated circuit (ASIC), graphics processing unit (GPU), image signal processor (ISP), image processing unit (IPU), arithmetic logic unit (ALU), complex programmable logic device (CPLD), field programmable gate array (FPGA), or similar components or combinations of the above components. The processor 110 is connected to the storage medium 120 and the transceiver 130, and can access and execute a number of modules and various application programs stored in the storage medium 120.

[0029] Storage medium 120 may be, for example, any type of fixed or removable random access memory (RAM), read-only memory (ROM), flash memory, hard disk drive (HDD), solid state drive (SSD), or similar component or combination of the above components capable of storing multiple modules or various application programs that can be executed by processor 110.

[0030] The transceiver 130 may transmit or receive signals wirelessly or via wires, and may further perform operations such as low noise amplification, impedance matching, frequency mixing, up or down frequency conversion, filtering, amplification, and other similar operations.

[0031] The radar 210 may include a transmitting circuit 211 and a receiving circuit 212. The radar 210 may transmit a radio frequency signal to a target via the transmitting circuit 211, and may receive a radar signal corresponding to the radio frequency signal (i.e., a reflected signal of the radio frequency signal transmitted to the target) via the receiving circuit 212. The radar 220, the radar 230, or the radar 240 may have the same or similar structure or function as the radar 210.

[0032] The radar may be disposed on the motorized vehicle to transmit and receive radio signals to targets within the motorized vehicle. When the detection system 10 includes multiple radars, the multiple radars may be configured to respectively detect multiple different targets. Figures 2A and 2B are schematic diagrams of a motorized vehicle 500 according to one embodiment of the present invention. Radar 210, radar 220, radar 230, and radar 240 may each be disposed at different locations on the motorized vehicle 500. 2A as an example, the radar 210 is disposed on the dashboard or the upper edge of the windshield (i.e., the junction of the windshield and the roof) and can detect a target (e.g., target 311) on the seat 31 (i.e., the driver's seat), the radar 220 is disposed on the upper edge of the windshield and can detect a target (e.g., target 321) on the seat 32 (i.e., the passenger's seat), the radar 230 is disposed on the back of the driver's seat and can detect a target on the seat 33, and the radar 240 is disposed on the back of the passenger's seat and can detect a target on the seat 34. The arrangement of the radars in the motor vehicle is determined according to actual needs, and the present invention is not limited thereto. For example, if the rear seat occupant that needs to be detected is a child or infant sitting in a rear-facing safety seat, the radar or radars may be positioned on the roof or upper edge of the rear vehicle window above the rear seat position in the motor vehicle cabin, facing radar 240 and a safety seat, such as safety seat 341, as depicted in FIG. 2B.

[0033] In one embodiment, the multiple radars of detection system 10 may be positioned at mirror locations on motorized vehicle 500. For example, radar 210 and radar 220 may be positioned at relative locations on a longitudinal centerline 510 of motorized vehicle 500, radar 230 and radar 240 may be positioned at relative locations on a longitudinal centerline 510 of motorized vehicle 500, radar 210 and radar 230 may be positioned at relative locations on a lateral centerline 520 of motorized vehicle 500, and radar 220 and radar 240 may be positioned at relative locations on a lateral centerline 520 of motorized vehicle 500.

[0034] 3 is a flow diagram of a method for detecting vital signs according to an embodiment of the present invention, where the method can be implemented by the detection system 10 depicted in FIG. 1. In step S301, the server 100 transmits a radio frequency signal via the radar 210 (and / or the radars 220, 230, or 240) and receives a radar signal corresponding to the radio frequency signal. The radio frequency signal may include an outgoing in-phase component and an outgoing quadrature component, and the radar signal may include a received in-phase component and a received quadrature component.

[0035] In one embodiment, the symbols of the transmitted quadrature components of the radio frequency signals emitted by different radars may be orthogonal to each other, i.e., the dot product of the symbols of the transmitted quadrature components of the different radio frequency signals may be 0. Also, the average value of the transmitted quadrature components may be 0. For example, assuming that the symbols of the transmitted quadrature components of the radio frequency signals emitted by radar 210 are a periodically repeating sequence [1 1 1 1 1 1 1 1], the symbols of the transmitted quadrature components of the radio frequency signals emitted by radar 220 may be a periodically repeating sequence [1 1 1 1 -1 -1 -1 -1 -1], the symbols of the transmitted quadrature components of the radio frequency signals emitted by radar 230 may be a periodically repeating sequence [1 1 -1 -1 1 1 -1 -1], and the symbols of the transmitted quadrature components of the radio frequency signals emitted by radar 240 may be a periodically repeating sequence [1 -1 1 -1 1 -1 1 -1 -1]. The inner product of any two of the arrays [1 1 1 1 1 1 1 1], [1 1 1 1 -1 -1 -1 -1], [1 1 -1 -1 1 1 -1 -1], and [1 -1 1 -1 1 -1 1 -1 -1] is equal to 0. In addition, the average value of each of the arrays [1 1 1 1 1 1 1 1], [1 1 1 1 -1 -1 -1 -1], [1 1 -1 -1 1 1 -1 -1], and [1 -1 1 -1 1 -1 1 -1 -1] is equal to 0. Therefore, the radar 210, the radar 220, the radar 230, and the radar 240 do not interfere with each other.

[0036] Fig. 4 is a circuit diagram of a transmission circuit of a radar according to an embodiment of the present invention. In Fig. 4, the transmission circuit 211 of the radar 210 and the transmission circuit 221 of the radar 220 (not shown in Fig. 1) are realized by the same circuit, but the present invention is not limited to this. For example, the transmission circuit 211 of the radar 210 and the transmission circuit 221 of the radar 220 can also be realized by separate circuits independent of each other.

[0037] The transmission circuit 211 may include a phase-locked loop circuit 41, a frequency divider 42, a mixer 43, a phase shifter 44, a mixer 45, and an adder 46. An input terminal of the phase-locked loop circuit 41 may be connected to a signal source to receive a signal S1. An input terminal of the frequency divider 42 may be connected to an output terminal of the phase-locked loop circuit 41, and an output terminal of the frequency divider 42 may be connected to an input terminal of the phase-locked loop circuit 41. The frequency of the signal output by the phase-locked loop circuit 41 may be j times the frequency of the signal S1, where j is a positive integer.

[0038] The two input terminals of the mixer 43 are connected to a high-potential voltage source V DD and an output terminal of the phase-locked loop circuit 41, respectively. An input terminal of the phase shifter 44 may be connected to the output terminal of the phase-locked loop circuit 41. Two input terminals of the mixer 45 may be connected to a signal source of the periodically oscillating signal S1 and to the output terminal of the phase shifter 44, respectively. Two input terminals of the summer 46 may be connected to the output terminal of the mixer 43 and to the output terminal of the mixer 45, respectively. In one embodiment, the symbols of the signal S1 are coupled to a voltage source V DD The symbols of the signal S1 may be orthogonal to each other, and the average value of the symbols of the signal S1 may be 0. For example, the voltage source V DD can be viewed as a periodically repeating sequence

[0011] , then the symbols of signal S1 can be viewed as a periodically repeating sequence [1 -1].

[0039] The output terminal of the summer 46 may be connected to a high pass filter and an antenna, and the radio frequency signal V is TX (t) is output, where V I (t) denotes the time-varying value of the transmitted in-phase component (also called the transmitted in-phase symbol) output by the mixer 43, and V Q (t) denotes the time-varying value of the transmitted quadrature component (also called the transmitted quadrature symbol) output by the mixer 45, and ω LO denotes the frequency of the local oscillator. V I (t) and V Q (t) can be mutually orthogonal, V I (t) or VQ The average value of (t) may be 0. [Formula 1] TIFF2025023864000002.tif11161

[0040] Taking the radar 210 as an example, a transmitter circuit 211 of the radar 210 transmits a radio frequency signal V TX After transmitting (t), the receiving circuit 212 of the radar 210 receives the radio frequency signal V as shown in formula (2). TX The radar signal V corresponding to (t) RX (t), where α is the radio frequency signal V TX (t) attenuation, φ OBJ where d(t) denotes the phase difference due to the reflection, and D denotes the distance between the radar 210 and the target (e.g.: seat 31 or target 311). Formula (2) may be approximated by formula (3), where d(t) may denote the constant portion of the distance D, and d(t) may denote the moving portion of the distance D. [Formula 2] TIFF2025023864000003.tif43160

[0041] Meanwhile, the transmission circuit 221 may include a phase-locked loop circuit 41, a frequency divider 42, a frequency divider 47, a mixer 48, a phase shifter 49, a mixer 50, and an adder 51. An input terminal of the phase-locked loop circuit 41 may be connected to a signal source and may receive a signal S1. An input terminal of the frequency divider 42 may be connected to an output terminal of the phase-locked loop circuit 41, and an output terminal of the frequency divider 42 may be connected to an input terminal of the phase-locked loop circuit 41. The frequency of the signal output by the phase-locked loop circuit 41 may be M times the frequency of the signal S1, where M is a positive integer. An input terminal of the frequency divider 43 may be connected to a signal source and may receive the incoming signal S1. Furthermore, the frequency of the signal output by the output terminal of the frequency divider 47 may be 0.5 times the frequency of the signal S1. For example, if the symbols of the signal S1 are in the cyclically repeating sequence [1 -1], then the symbols of the signal output by the frequency divider 47 may be in the cyclically repeating sequence [1 1 -1 -1].

[0042] The two input terminals of the mixer 48 are connected to a high-potential voltage source V DD and the output terminal of the phase locked loop circuit 41. The input terminal of the phase shifter 49 may be connected to the output terminal of the phase locked loop circuit 41. The two input terminals of the mixer 50 may be connected to the output terminal of the frequency divider 47 and the output terminal of the phase shifter 49, respectively. The two input terminals of the adder 51 may be connected to the output terminal of the mixer 48 and the output terminal of the mixer 50, respectively. The output terminal of the adder 51 may be connected to a high pass filter and an antenna, and can output a radio frequency signal.

[0043] Returning to FIG. 3, in step S302, the detection system 10 may perform pre-processing on the radar signal of the radar 210 (and / or the radar 220, the radar 230, and the radar 240) to obtain a processed signal.

[0044] In one embodiment, the processor 110 of the server 100 may perform pre-processing on the radar signal to obtain a processed signal. RX Taking (t) as an example, first, the processor 110 detects the radar signal V RX (t) is subjected to in-phase quadrature demodulation (IQ-demodulation), and the received in-phase component I RX (t) and the received quadrature component Q RX (t) can be obtained, where V I V I indicates the inherent DC bias corresponding to (t), and V Q V Q (t) indicates the inherent DC bias corresponding to A I denotes the gain of the receiving channel corresponding to the in-phase component, and A Q denotes the gain of the receiving channel corresponding to the quadrature component, and φ0 denotes the gain of the local oscillator of the receiving circuit 212 and the radar signal V RX (t) and VI and V Q can be orthogonal to each other. For example, V I If is a periodically repeating array [1 1 1 1], then V Q may be a periodically repeating sequence [1 −1 1 −1]. [Formula 3] TIFF2025023864000004.tif22160TIFF2025023864000005.tif22155

[0045] The processor 110 then calculates the received in-phase component I as shown in formula (6). RX (t) and V Q A convolution operation is performed on (t), and a multiply-accumulate (MAC) operation is performed on the result of the convolution operation to obtain the accumulated value I RX (n), where T is the time interval for which the symbol changes. For example, V Q If is the array [1 -1], then V Q The value of Q changes from "1" to "-1" after a time interval T. Meanwhile, the processor 110 calculates the received quadrature component Q as shown in formula (7). RX (t) and V Q A convolution operation is performed on (t), and a multiplication and accumulation operation is performed on the result of the convolution operation to obtain the cumulative value Q RX (n) can be obtained. [Formula 4] TIFF2025023864000006.tif21161

[0046] The processor 110 then calculates the received in-phase component I as shown in formula (8). RX (t) and V Q A difference operation (e.g., a moving difference operation) is performed on the result of the convolution operation of (t) to obtain the difference ΔI RX On the other hand, the processor 110 can obtain the received quadrature components Q RX (t) and V QA difference operation (for example, a moving difference operation) is performed on the result of the convolution operation of (t) to obtain the difference ΔQ RX (n) can be obtained. [Formula 5] TIFF2025023864000007.tif23163

[0047] The processor 110 calculates the difference ΔI RX (n) and cumulative value Q RX The processor 110 can calculate the ratio of the difference ΔQ RX (n) and cumulative value I RX The processor 110 can process the formula (10), the formula (11), or the product formula (12) to generate the processed signal PS1. [Formula 6] TIFF2025023864000008.tif34157

[0048] As described above, formula (10) or formula (11) is essentially the rate of change of the distance between the target and the radar over time. Formula (10) can be accumulated over time, or formula (11) can be accumulated over time, to determine the relationship between the distance of the target relative to the radar and time, and the value obtained after accumulation is completed can be used as the processed signal PS1. Also, the relationship between the distance of the target relative to the radar and time can be determined by accumulating the square root of the absolute value of formula (12) over time. Formula (12) can be used to further determine A in formula (10) or formula (11), I (i.e.: the gain of the receiving channel corresponding to the in-phase component) and A Q (i.e.: the gain of the receiving channel corresponding to the quadrature component) is removed, I The rate of change of A I (degree of change over time) and A Q The rate of change of A Q This can solve the problem of inconsistency in the degree of change over time.

[0049] The processor 110 may generate processed signals PS2, PS3, and PS4 corresponding to the radars 220, 230, and 240, respectively, based on a method similar to that for generating the processed signal PS1 corresponding to the radar 210.

[0050] In one embodiment, while the processor 110 performs pre-processing on the radar signal, the processor 110 may perform low-pass filtering on the radar signal to remove signals unrelated to heartbeat or respiration (e.g., noise caused by vibration of the powered vehicle 500) to obtain a processed signal. For example, the processor 110 may apply moving average filtering of X sampling points to the radar signal to obtain a processed signal. The processor 110 may perform the moving average filtering based on design parameters of 3 dB frequency=5 Hz; zero frequency=12 Hz; and sampling frequency=12*X Hz.

[0051] In one embodiment, the receiving circuit of the radar can perform pre-processing on the radar signal to obtain a processed signal. Taking the radar 210 as an example, FIG. 5 is a circuit diagram of the receiving circuit 212 of the radar 210 according to an embodiment of the present invention. The receiving circuit 212 receives the radar signal V RX A pre-processing can be performed on (t) to obtain a processed signal. The receiver circuit 212 may include a phase-locked loop circuit 61, a frequency divider 62, a mixer 63, a phase shifter 64, a mixer 65, a low-pass filter 66, a low-pass filter 67, a mixer 68, a mixer 69, an analog-to-digital converter 70, an analog-to-digital converter 71, a serial-in parallel-out (SIPO) shift register 72, a serial-in parallel-out shift register 73, an adder 74, an adder 75, a subtractor 76, and a subtractor 77.

[0052] An input terminal of the phase-locked loop circuit 61 is connected to a signal source to receive a periodically oscillating signal S2. In one embodiment, the symbols of the signal S2 are represented by a radio frequency signal VTX The transmitted quadrature component symbols of (t) (i.e.: V Q ) The input terminal of the frequency divider 62 may be connected to the output terminal of the phase-locked loop circuit 61, and the output terminal of the frequency divider 62 may be connected to the input terminal of the phase-locked loop circuit 61. The frequency of the signal output by the phase-locked loop circuit 61 may be j times the frequency of the signal S2, where j is a positive integer.

[0053] The two input terminals of the mixer 63 are connected to the output terminal of the phase-locked loop circuit 61 and the radar signal V RX The output terminal of the mixer 63 may be connected to an input terminal of a low-pass filter 66. The input terminal of the phase shifter 64 may be connected to an output terminal of the phase-locked loop circuit 61. The two input terminals of the mixer 65 receive the radar signal V RX The output terminal of the mixer 65 may be connected to an input terminal of a low pass filter 67. The radar signal V RX After (t) passes through the mixer 63 and the low-pass filter 66, the radar signal V RX (t) is the received in-phase component I RX (t), while the radar signal V RX After (t) passes through mixer 65 and low-pass filter 67, radar signal V RX (t) is the received quadrature component Q RX May be converted to (t).

[0054] Two input terminals of the mixer 68 may be connected to the output terminal of the low-pass filter 66 and a signal source of the signal S2, respectively, and an output terminal of the mixer 68 may be connected to an input terminal of an analog-to-digital converter 70. An input terminal of a shift register 72 may be connected to an output terminal of the analog-to-digital converter 70, and multiple output terminals of the shift register 72 may be connected to an adder 74 and may output parallel data to the adder 74. The receiving circuit 212 receives the in-phase component I RX (t) and V QAfter the result of the convolution is converted into a digital signal by the analog-to-digital converter 70, the shift register 72 and the adder 74 perform a multiply-and-accumulate operation on the result to obtain an accumulated value I RX (n) can be obtained. Meanwhile, the two input terminals of the subtractor 76 may be respectively connected to the input terminal of the shift register 72 and the last output terminal of the shift register 72 (for example: the output of the last stage of the shift register 72, where the data stored in the last stage is the data that has been delayed the longest before being output to the shift register 72). The receiving circuit 212 performs a difference operation on the result of the convolution operation via the subtractor 76, and obtains a difference ΔI RX (n) can be obtained.

[0055] Meanwhile, two input terminals of the mixer 69 may be connected to the output terminal of the low-pass filter 66 and the signal source of the signal S2, respectively, and an output terminal of the mixer 69 may be connected to an input terminal of an analog-to-digital converter 71. An input terminal of the shift register 73 may be connected to the output terminal of the analog-to-digital converter 71, and multiple output terminals of the shift register 73 may be connected to an adder 75 to output parallel data to the adder 75. The receiving circuit 212 receives the received quadrature component Q via the mixer 69. RX (t) and V Q After the result of the convolution is converted into a digital signal by the analog-to-digital converter 71, the shift register 73 and the adder 75 perform a multiply-and-accumulate operation on the result to obtain the cumulative value Q RX On the other hand, the two input terminals of the subtractor 77 may be respectively connected to the input terminal of the shift register 73 and the last output terminal of the shift register 73 (for example: the output of the last stage of the shift register 73, where the data stored in the last stage is the data that has been delayed the longest before being output to the shift register 73). The receiving circuit 212 performs a difference operation on the result of the convolution operation through the subtractor 77, and obtains a difference ΔQ RXThe receiver circuit 212 performs a difference calculation on the result of the convolution calculation via the subtractor 77 to obtain the difference ΔQ RX (n) can be obtained. The period of the signal S2 may be an integer multiple of the sampling period of the analog-to-digital converter 70 (or 71), and the number of bits of the shift register 72 and the shift register 73 may be an integer multiple of the ratio of the period of the signal S2 to the sampling period of the analog-to-digital converter 70 (or 71).

[0056] Accumulation value I RX (n), cumulative value Q RX (n), difference ΔI RX (n) and difference ΔQ RX After obtaining (n), the receiving circuit 212 (or the server 100) further calculates the cumulative value I RX (n), cumulative value Q RX (n), difference ΔI RX (n) and difference ΔQ RX Based on (n), a processed signal PS1 of the radar 210 expressed by formula (12) can be generated.

[0057] Returning to FIG. 3, in step S303, the processor 110 can determine whether the power component of the processed signal PS1 of the radar 210 is greater than a threshold. Here, the power component may include the power of the processed signal PS1 in a specific frequency range (for example: a frequency range related to a vital sign such as breathing or heartbeat: 0.25 Hz to 3 Hz). If the power component is greater than the threshold, it indicates that a target 311 is sitting on the seat 31 detected by the radar 210, and the processor 110 can execute step S305. If the power component is equal to or less than the threshold, it indicates that no target is sitting on the seat 31 detected by the radar 210, and the processor 110 can execute step S304. For example, the processor 110 can perform a time-frequency transform (for example: perform a Fourier transform on the processed signal) on the processed signal PS1 to generate a spectrum of the processed signal PS1, and obtain a power component corresponding to a specific frequency range from the spectrum. The processor 110 can determine whether the power component of the processed signal PS1 is greater than a threshold. If the processed signal PS1 is greater than the threshold, it indicates that there is a target 311 on the seat 31 detected by the radar 210. If the processed signal PS1 is less than or equal to the threshold, it indicates that there is no target on the seat 31 detected by the radar 210. In a similar manner, the processor 110 can determine whether there is a target on the seat 32 detected by the radar 220, the seat 33 detected by the radar 230, or the seat 34 detected by the radar 240.

[0058] In step S304, the processor 110 can determine that no target is present on the seat 31 detected by the radar 210 and generate a detection result. The processor 110 can output the detection result via the transceiver 130.

[0059] In step S305, the processor 110 can determine whether there is a reference signal that can be used as the processed signal PS1. If there is a reference signal, proceed to step S306. If there is no reference signal, proceed to step S307. The reference signal includes, for example, a processed signal corresponding to another radar (a radar other than the radar 210, for example, the radar 220, the radar 230, or the radar 240) and having a power component equal to or less than a threshold. Taking FIG. 2 as an example, since a target 321 exists on the seat 32 detected by the radar 220, the power component of the processed signal PS2 corresponding to the radar 220 is greater than the threshold. On the other hand, since no target exists on the seat 33 detected by the radar 230 or the seat 34 detected by the radar 240, the power component of the processed signal PS3 corresponding to the radar 230 or the power component of the processed signal PS4 corresponding to the radar 240 is equal to or less than a threshold. Therefore, processor 110 may determine that processed signal PS3 or processed signal PS4 may be used as a reference signal for processed signal PS1, and that processed signal PS2 may not be used as a reference signal for processed signal PS1. If seat 32, seat 33, and seat 34 are all occupied by targets, processor 110 may determine that a reference signal for processed signal PS1 does not exist.

[0060] In step S306, the processor 110 can subtract the reference signal (e.g., the processed signal PS3 corresponding to the radar 230) from the processed signal PS1 to obtain a vital sign corresponding to the target 311 detected by the radar 210. Here, the vital sign may include a time-varying signal indicative of a position change of the target 311 (e.g., a movement of the chest of the target 311). The processor 110 can output the vital sign via the transceiver 130.

[0061] In step S307, the processor 110 can obtain a vital sign corresponding to the target 311 detected by the radar 210 according to the lookup table. The processor 110 can output the vital sign via the transceiver 130.

[0062] Specifically, the storage medium 120 may store a lookup table corresponding to the powered vehicle 500 in advance. Here, the lookup table may record a mapping relationship between the engine speed and the vibration frequency. For example, the lookup table may record "when the engine speed of the powered vehicle 500 is 600-1200 revolutions per minute (RPM), the vibration frequency of the powered vehicle 500 is 10-20 Hz." The processor 110 may be communicatively connected to the powered vehicle 500 via the transceiver 130 and may acquire dashboard information. Here, the dashboard information may include the engine speed of the powered vehicle 500. The processor 110 may query the lookup table in the storage medium 120 based on the dashboard information to acquire the vibration frequency of the powered vehicle 500. After acquiring the vibration frequency, the processor 110 may process the processed signal PS1 of the radar 210 based on the vibration frequency to acquire the vital signs of the target 311. For example, the processor 110 can apply a notch filter, a low-pass filter, or other digital signal processing filter (DSP filter) to the processed signal PS1 to remove the vibration frequency in the processed signal PS1 and obtain the vital sign of the target 311. Here, the notch frequency of the digital signal processing filter can be an integer multiple of the vibration frequency.

[0063] In one embodiment, the radio frequency signals emitted by the different radars (eg, radars 210, 220, 230, and 240) are orthogonal frequency division multiplexing (OFDM) signals.

[0064] FIG. 6 is a flow diagram of a vital signs detection method according to an embodiment of the present invention, where the detection method is applied to a motor vehicle and can be implemented by the detection system 10 shown in FIG. 1. In step S601, a first radio frequency signal is transmitted via a first radar, and a first radar signal corresponding to the first radio frequency signal is received. Here, the first radio frequency signal includes a first transmitted in-phase component and a first transmitted quadrature component. In step S602, an in-phase quadrature demodulation is performed on the first radar signal to obtain a first received in-phase component and a first received quadrature component. In step S603, a first convolution operation is performed on a first symbol corresponding to the first received in-phase component and the first transmitted quadrature component, and a first product-sum operation is performed on a first result of the first convolution operation to obtain a first accumulation value. In step S604, a second convolution operation is performed on a first symbol corresponding to the first received quadrature component and the first transmitted quadrature component, and a second product-sum operation is performed on a second result of the second convolution operation to obtain a second accumulated value. In step S605, a first processed signal is generated based on the first accumulated value and the second accumulated value. In step S606, a vital sign corresponding to the first radar is generated based on the first processed signal, and the vital sign is output. Here, a first symbol of the first transmitted quadrature component is orthogonal to a transmitted in-phase symbol of the first transmitted in-phase component, and the first symbol is a symbol with an average value of 0.

[0065] In summary, the detection system of the present invention can detect the seat of the motor vehicle through the radio frequency signal transmitted by the radar and obtain the detection result. The transmitting circuit of the radar can use two symbols, , and , which are orthogonal to each other, to generate an outgoing in-phase component and an outgoing quadrature component of the radio frequency signal. The receiving circuit of the radar can use the symbols of the outgoing quadrature components to perform processes including convolution and product-sum operations, etc. to process the radar signal and obtain a processed signal. If there are other radars in the motor vehicle that have obtained other detection results that can be used as reference signals, the detection system can obtain the vital signs of the subject by comparing the comparative processed signal and the reference signal. Meanwhile, the detection system can further obtain the vital signs according to a look-up table based on the dashboard information of the motor vehicle. Compared with the conventional vital signs monitoring system using a non-contact method, the detection system of the present invention can accurately measure the vital signs of the subject in an unstable environment. [Industrial Applicability]

[0066] The vital signs detection system and method of the present invention can be applied to related applications in vehicles such as automobiles. [Explanation of symbols]

[0067] 10: Detection system 100: Server 110: Processor 120:Storage medium 130: Transmitter / receiver 210, 220, 230, 240: Radar 211, 221: Transmitting circuit 212: Receiving circuit 31, 32, 33, 34: Seats 311, 321: Goal 341: Safety seat 41, 61: Phase-locked loop circuit 42, 47, 62: Frequency divider 43, 45, 48, 50, 63, 65, 68, 69: Mixer 44, 49, 64: Phase shifter 46, 51, 74, 75: Adders 500: Powered vehicles 510: Vertical centerline 520: Lateral center line 66, 67: Low pass filter 70, 71: Analog-to-digital converter 72, 73: Shift register 76, 77: Subtractor S301, S302, S303, S304, S305, S306, S307, S601, S602, S603, S604, S605, S606: Process

Claims

1. 1. A vital signs detection system for use in a motor vehicle, comprising: A first radar; and A server communicatively connected to the first radar, transmitting a first radio frequency signal via the first radar, the first radio frequency signal including a first outgoing in-phase component and a first outgoing quadrature component, and receiving a first radar signal corresponding to the first radio frequency signal; performing in-phase and quadrature demodulation on the first radar signal to obtain a first received in-phase component and a first received quadrature component; performing a first convolution operation on a first symbol corresponding to the first received in-phase component and the first transmitted quadrature component, and performing a first multiply-accumulate operation on a first result of the first convolution operation to obtain a first accumulation value; performing a second convolution operation on the first symbol corresponding to the first received quadrature component and the first transmitted quadrature component, and performing a second multiply-accumulate operation on a second result of the second convolution operation to obtain a second accumulation value; generating a first processed signal based on the first accumulated value and the second accumulated value; generating a vital sign corresponding to the first radar based on the first processed signal, and outputting the vital sign, wherein the first symbol of the first transmitted quadrature component is orthogonal to an transmitted in-phase symbol of the first transmitted in-phase component, and the first symbol is a symbol having an average value of 0; and the server configured to execute the above.

2. a second radar communicatively connected to the server; The server, transmitting a second radio frequency signal via the second radar and receiving a second radar signal corresponding to the second radio frequency signal; performing pre-processing on the second radar signal to obtain a second processed signal; generating the vital sign based on the first processed signal and the second processed signal; The detection system of claim 1 , further configured to perform:

3. The server, in response to a first power component of the first processed signal being greater than a threshold and a second power component of the second processed signal being equal to or less than the threshold, subtracting the second processed signal from the first processed signal to obtain the vital sign corresponding to the first radar; determining that a target is not present and generating a detection result in response to the first power component being less than or equal to the threshold; The detection system of claim 2 further configured to perform:

4. The server, a communication device connected to the motor vehicle to obtain dashboard information and, based on the dashboard information, querying a lookup table to obtain a vibration frequency; processing the first processed signal based on the vibration frequency to obtain the vital sign; The detection system of claim 1 , further configured to perform:

5. The dashboard information includes engine speed. The detection system of claim 4.

6. the first symbols of the first transmitted quadrature component of the first radio frequency signal are mutually orthogonal to second symbols of the second transmitted quadrature component of the second radio frequency signal; The detection system of claim 2 .

7. the first radio frequency signal and the second radio frequency signal are orthogonal frequency division multiplexed signals; The detection system of claim 2 .

8. The server, performing a first difference calculation based on the first result to obtain a first difference; calculating a ratio between the first difference and the second accumulated value to generate the first processed signal; The detection system of claim 1 , further configured to perform:

9. The server, performing low pass filtering on the first radar signal to obtain the first processed signal; The detection system of claim 1 , further configured to perform:

10. the vital signs include a time-varying signal indicative of a change in position; The detection system of claim 1 .

11. 1. A method for detecting vital signs applied to a motor vehicle, comprising: transmitting a first radio frequency signal via a first radar, the first radio frequency signal including a first transmitted in-phase component and a first transmitted quadrature component, and receiving a first radar signal corresponding to the first radio frequency signal; performing in-phase and quadrature demodulation on the first radar signal to obtain a first received in-phase component and a first received quadrature component; performing a first convolution operation on a first symbol corresponding to the first received in-phase component and the first transmitted quadrature component, and performing a first multiply-accumulate operation on a first result of the first convolution operation to obtain a first accumulation value; performing a second convolution operation on the first symbol corresponding to the first received quadrature component and the first transmitted quadrature component, and performing a second multiply-accumulate operation on a second result of the second convolution operation to obtain a second accumulation value; generating a first processed signal based on the first accumulated value and the second accumulated value; generating a vital sign corresponding to the first radar based on the first processed signal, and outputting the vital sign, wherein the first symbol of the first transmitted quadrature component is orthogonal to an transmitted in-phase symbol of the first transmitted in-phase component, and the first symbol is a symbol having an average value of 0; A detection method comprising:

12. transmitting a second radio frequency signal via a second radar and receiving a second radar signal corresponding to the second radio frequency signal; performing pre-processing on the second radar signal to obtain a second processed signal; generating the vital sign based on the first processed signal and the second processed signal; The method of claim 11 , further comprising:

13. in response to a first power component of the first processed signal being greater than a threshold and a second power component of the second processed signal being equal to or less than the threshold, subtracting the second processed signal from the first processed signal to obtain the vital sign corresponding to the first radar; determining that a target is not present and generating a detection result in response to the first power component being less than or equal to the threshold; The method of claim 12, further comprising:

14. obtaining dashboard information from the motor vehicle and querying a lookup table based on the dashboard information to obtain a vibration frequency; processing the first processed signal based on the vibration frequency to obtain the vital sign; The method of claim 11 , further comprising:

15. The dashboard information includes engine speed. The detection method according to claim 14.

16. the first symbols of the first transmitted quadrature component of the first radio frequency signal are mutually orthogonal to second symbols of the second transmitted quadrature component of the second radio frequency signal; The detection method according to claim 12.

17. the first radio frequency signal and the second radio frequency signal are orthogonal frequency division multiplexed signals; The detection method according to claim 12.

18. generating the first processed signal based on the first accumulation value and the second accumulation value, performing a first difference calculation based on the first result to obtain a first difference; calculating a ratio between the first difference and the second accumulated value to generate the first processed signal; The detection method according to claim 11 , comprising:

19. performing low pass filtering on the first radar signal to obtain the first processed signal. The detection method according to claim 11.

20. the vital signs include a time-varying signal indicative of a change in position; The detection method according to claim 11.

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