Life sign detection system and detection method

Abstract

The invention provides a detection system and a detection method for life signs. The method includes: transmitting, by a first radar, a first radio frequency signal, and receiving a first radar signal corresponding to the first radio frequency signal; performing in-phase quadrature demodulation on the first radar signal to obtain a first receiving in-phase component and a first receiving quadrature component; performing a first convolution operation on the first received in-phase component and the first symbol, and performing a first product shift accumulation operation on a first result of the first convolution operation to obtain a first accumulated value; performing a second convolution operation on the first received orthogonal component and the first symbol, and performing a second product shift accumulation operation on a second result of the second convolution operation to obtain a second accumulated value; and generating a life sign according to the first accumulated value and the second accumulated value.

Description

Technical Field

[0001] The present invention relates to a detection system and a detection method, and in particular to a detection system and a detection method of life signs. Background Art

[0002] Vital sign detection technology can be applied to fields such as healthcare, driving monitoring or home care. Traditional vital sign monitoring systems can measure the vital signs of the subject through wearable devices, but wearable devices may cause discomfort to the subject. In order to reduce the discomfort of the subject, the current monitoring system has been improved to measure the vital signs of the subject using wireless radio frequency signals. However, the vital signs measured using wireless 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

[0003] The present invention provides a vital sign detection system and a detection method, which can measure the vital sign of a subject in a power vehicle in a non-contact manner.

[0004] A life sign detection system of the present invention is applicable to a power vehicle and includes a first radar and a server. The server is communicatively connected to the first radar and is configured to perform: transmitting a first radio frequency signal through the first radar, and receiving a first radar signal corresponding to the first radio frequency signal, wherein the first radio frequency signal includes 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 the first received in-phase component and a first symbol corresponding to the first transmitted quadrature component, and performing a first product-shift-accumulate operation on a first result of the first convolution operation to obtain a first accumulated value; performing a second convolution operation on the first received quadrature component and a first symbol corresponding to the first transmitted quadrature component, and performing a second product-shift-accumulate operation on a second result of the second convolution operation to obtain a second accumulated value; generating a first processed signal according to the first accumulated value and the second accumulated value; and generating a vital sign corresponding to the first radar according to the first processed signal, and outputting the vital sign, wherein the first symbol of the first transmitted quadrature component is orthogonal to the 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 comprises a second radar. The second radar is communicatively connected to the server, wherein the server is further configured to execute: transmitting a second radio frequency signal through 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; and generating a life sign according to the first processed signal and the second processed signal.

[0006] In one embodiment of the present invention, the above-mentioned server is also configured to execute: in response to the first power component of the first processed signal being greater than a threshold and the second power component of the second processed signal being less than or equal to a threshold, subtracting the second processed signal from the first processed signal to obtain a life sign corresponding to the first radar.

[0007] In one embodiment of the present invention, the server is further configured to execute: communicating with the power vehicle to obtain dashboard information, and querying a lookup table according to the dashboard information to obtain a vibration frequency; and processing the first processing signal according to the vibration frequency to obtain a vital sign.

[0008] In one embodiment of the present invention, the instrument panel information includes engine speed.

[0009] In one embodiment of the present invention, the first symbol of the first transmitted orthogonal component of the first RF signal and the second symbol of the second transmitted orthogonal component of the second RF signal are orthogonal to each other.

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

[0011] In an embodiment of the present invention, the server is further configured to: perform a first difference operation according to the first result to obtain a first difference; and calculate a ratio of the first difference to the second accumulated value to generate a first processed signal.

[0012] In one embodiment of the present invention, the server is further configured to execute: performing a low-pass filter on the first radar signal to obtain a first processed signal.

[0013] In one embodiment of the present invention, the above-mentioned vital signs include a time-varying signal indicating a position change.

[0014] A method for detecting life signs of the present invention is applicable to a powered vehicle, comprising: transmitting a first radio frequency signal through a first radar, and receiving a first radar signal corresponding to the first radio frequency signal, wherein the first radio frequency signal comprises a first transmitted in-phase component and a first transmitted quadrature component; performing in-phase orthogonal 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 the first received in-phase component and a first symbol corresponding to the first transmitted quadrature component, and performing a first product-moving-accumulation operation on a first result of the first convolution operation to obtain a first accumulated value; performing a second convolution operation on the first received quadrature component and a first symbol corresponding to the first transmitted quadrature component, and performing a second product-moving-accumulation operation on a second result of the second convolution operation to obtain a second accumulated value; generating a first processed signal according to the first accumulated value and the second accumulated value; and generating a life sign corresponding to the first radar according to the first processed signal, and outputting the life sign, wherein the first symbol of the first transmitted quadrature component is orthogonal to the 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-mentioned detection method further includes: transmitting a second RF signal through a second radar, and receiving a second radar signal corresponding to the second RF signal; performing pre-processing on the second radar signal to obtain a second processed signal; and generating a life sign according to the first processed signal and the second processed signal.

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

[0017] In one embodiment of the present invention, the detection method further comprises: obtaining dashboard information from the power vehicle, and querying a lookup table to obtain a vibration frequency according to the dashboard information; and obtaining a vital sign by processing a signal according to the vibration frequency.

[0018] In one embodiment of the present invention, the instrument panel information includes engine speed.

[0019] In one embodiment of the present invention, the first symbol of the first transmitted orthogonal component of the first RF signal and the second symbol of the second transmitted orthogonal component of the second RF signal are orthogonal to each other.

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

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

[0022] In one embodiment of the present invention, the detection method further comprises: performing a low-pass filter on the first laser signal to obtain a first processed signal.

[0023] In one embodiment of the present invention, the above-mentioned vital signs include a time-varying signal indicating a position change.

[0024] Based on the above, the detection system of the present invention can improve the accuracy of life signs measured by radar in an unstable environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a vital sign detection system is shown according to an embodiment of the present invention.

[0026] Figure 2A and 2B A schematic diagram of a power vehicle is shown according to an embodiment of the present invention.

[0027] Figure 3 A flow chart of a method for detecting vital signs is shown according to an embodiment of the present invention.

[0028] Figure 4 A circuit diagram of a transmitting circuit of a radar is shown according to an embodiment of the present invention.

[0029] Figure 5 A circuit diagram of a receiving circuit of a radar is shown according to an embodiment of the present invention.

[0030] Figure 6 A flow chart of a method for detecting vital signs is shown according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0032] Figure 1According to an embodiment of the present invention, a schematic diagram of a vital sign detection system 10 is shown. The detection system 10 may include a server 100 and i radars connected to the server 100 for communication, where i is an arbitrary positive integer. In the following description, N is assumed to be 4, and the i radars may include radar 210, radar 220, radar 230, and radar 240. Radar 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 may include but are not limited to breathing or heartbeat.

[0033] 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 other similar components or combinations thereof. The processor 110 may be coupled to the storage medium 120 and the transceiver 130, and access and execute multiple modules and various applications stored in the storage medium 120.

[0034] The storage medium 120 is, 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 element or a combination of the above elements, and is used to store multiple modules or various applications that can be executed by the processor 110.

[0035] The transceiver 130 transmits or receives signals in a wireless or wired manner. The transceiver 130 may also perform operations such as low noise amplification, impedance matching, mixing, up or down frequency conversion, filtering, amplification, and the like.

[0036] 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 through 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) through 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.

[0037] The radar may be disposed in a power vehicle to transmit and receive wireless signals to a target in the power vehicle. When the detection system 10 includes a plurality of radars, the plurality of radars may be configured to measure a plurality of different targets respectively. Figure 2A and 2B A schematic diagram of a power vehicle 500 is shown according to an embodiment of the present invention. Radar 210, radar 220, radar 230 and radar 240 may be respectively disposed at different positions in the power vehicle 500. Figure 2A For example, radar 210 may be disposed on the dashboard or the upper edge of the front windshield (i.e., the junction of the front windshield and the roof) to detect targets (e.g., target 311) on seat 31 (i.e., the driver's seat), radar 220 may be disposed on the upper edge of the front windshield to detect targets (e.g., target 321) on seat 32 (i.e., the front passenger seat), radar 230 may be disposed on the back of the driver's seat to detect targets on seat 33, and radar 240 may be disposed on the back of the front passenger seat to detect targets on seat 34. In practice, the configuration of radars in a power vehicle depends on actual needs, and the present invention is not limited thereto. For example, when the rear seat passenger to be detected is a toddler or infant in a rear-facing safety seat, one or more of the radars may be disposed on the roof above the rear seat position of the power vehicle's compartment or on the upper edge of the rear window, and facing the safety seat, such as Figure 2B Radar 240 and safety seat 341 are shown.

[0038] In one embodiment, the plurality of radars of the detection system 10 may be respectively arranged at mirror positions in the power vehicle 500. For example, the radar 210 and the radar 220 may be respectively arranged at relative positions of the longitudinal centerline 510 of the power vehicle 500, the radar 230 and the radar 240 may be respectively arranged at relative positions of the longitudinal centerline 510 of the power vehicle 500, the radar 210 and the radar 230 may be respectively arranged at relative positions of the transverse centerline 520 of the power vehicle 500, and the radar 220 and the radar 240 may be respectively arranged at relative positions of the transverse centerline 520 of the power vehicle 500.

[0039] Figure 3 According to an embodiment of the present invention, a flow chart of a method for detecting vital signs is shown, wherein the method may be performed as follows: Figure 1 The detection system 10 shown is implemented. In step S301, the server 100 may transmit a radio frequency signal through the radar 210 (and / or the radars 220, 230 or 240), and receive a radar signal corresponding to the radio frequency signal. The radio frequency signal may include a transmitted in-phase component and a transmitted quadrature component, and the radar signal may include a received in-phase component and a received quadrature component.

[0040] In one embodiment, the signs of the transmitted orthogonal components of the RF signals transmitted by different radars may be orthogonal to each other, that is, the inner product of the signs of the transmitted orthogonal components of the different RF signals may be zero. In addition, the average value of the signs of the transmitted orthogonal components may be zero. For example, assuming that the signs of the transmitted orthogonal components of the RF signal transmitted by the radar 210 are a periodically repeated sequence of [1 1 1 1 1 1 11], the signs of the transmitted orthogonal components of the RF signal transmitted by the radar 220 may be a periodically repeated sequence of [1 1 1 1 -1-1 -1-1], the signs of the transmitted orthogonal components of the RF signal transmitted by the radar 230 may be a periodically repeated sequence of [1 1 -1-1 1 1 -1-1], and the signs of the transmitted orthogonal components of the RF signal transmitted by the radar 240 may be a periodically repeated sequence of [1 -1 1 -1 1 -1 1 -1]. The inner product of any two of the sequence [1 1 1 1 1 1 1 1], the sequence [1 1 1 1 -1-1 -1-1], the sequence [1 1 -1-1 1 1 -1-1], and the sequence [1 -1 1 -1 1 -1 1 -1] is equal to zero. In addition, the average value of each of the sequence [1 1 1 1 1 1 1 1], the sequence [1 1 1 1 -1-1 -1-1], the sequence [1 1 -1-1 1 1 -1-1], and the sequence [1 -1 1 -1 1 -1 1 -1] is equal to zero. Accordingly, the radar 210, the radar 220, the radar 230, and the radar 240 do not interfere with each other.

[0041] Figure 4 A circuit diagram of a radar transmission circuit is shown according to an embodiment of the present invention. Figure 4 The transmitting circuit 211 of the radar 210 and the transmitting circuit 221 of the radar 220 (not shown) Figure 1 For example, the transmission circuit 211 of the radar 210 and the transmission circuit 221 of the radar 220 may be implemented by different circuits that are independent of each other.

[0042] The transmitting circuit 211 may include a phase-locked loop circuit 41, a divider 42, a mixer 43, a phase shifter 44, a mixer 45, and an adder 46. The input end of the phase-locked loop circuit 41 may be coupled to a signal source for receiving the signal S1. The input end of the divider 42 may be coupled to the output end of the phase-locked loop circuit 41, and the output end of the divider 42 may be coupled to the input end 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.

[0043] The two input terminals of the mixer 43 can be coupled to the high potential voltage source VDD and the output terminal of the phase-locked loop circuit 41, respectively. The input terminal of the phase shifter 44 can be coupled to the output terminal of the phase-locked loop circuit 41. The two input terminals of the mixer 45 can be coupled to the signal source of the periodically oscillating signal S1 and the output terminal of the phase shifter 44, respectively. The two input terminals of the adder 46 can be coupled to the output terminal of the mixer 43 and the output terminal of the mixer 45, respectively. In one embodiment, the sign of the signal S1 can be orthogonal to the sign represented by the voltage source VDD, and the average value of the sign of the signal S1 can be zero. For example, if the voltage source VDD can be regarded as a periodically repeated sequence [1 1], the sign of the signal S1 can be regarded as a periodically repeated sequence [1 -1].

[0044] The output terminal of the adder 46 can be coupled to a high pass filter and an antenna to output a radio frequency signal V TX (t), as shown in formula (1), where V I (t) represents the time-varying value of the transmitted in-phase component output by the mixer 43 (or called the transmitted in-phase symbol), V Q (t) represents the time-varying value of the transmitted orthogonal component output by the mixer 45 (or called the transmitted orthogonal symbol), and ω LO Represents the frequency of the local oscillator. V I (t) and V Q (t) may be orthogonal to each other, and V I (t) or V Q The average value of (t) can be zero.

[0045] V TX (t) = V I (t)cos(ω LO t)+V Q (t)sin(ω LO t)…(1)

[0046] Taking radar 210 as an example, the transmitting circuit 211 of radar 210 transmits a radio frequency signal V to the target. TX (t), the receiving circuit 212 of the radar 210 may receive the corresponding RF signal V TX (t) Radar signal V RX (t), as shown in formula (2), where α represents the RF signal V TX (t) attenuation, represents the phase difference caused by reflection, and D represents the distance between the radar 210 and the target (e.g., seat 31 or target 311). Formula (2) can be approximated by formula (3), where d0 can represent the constant portion of the distance D, and d(t) can represent the moving portion of the distance D.

[0047]

[0048]

[0049] On the other hand, the transmitting circuit 221 may include a phase-locked loop circuit 41, a divider 42, a divider 47, a mixer 48, a phase shifter 49, a mixer 50, and an adder 51. The input end of the phase-locked loop circuit 41 may be coupled to a signal source for receiving the signal S1. The input end of the divider 42 may be coupled to the output end of the phase-locked loop circuit 41, and the output end of the divider 42 may be coupled to the input end 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. The input end of the divider 43 may be coupled to a signal source for receiving the signal S1, and the frequency of the signal output by the output end of the divider 47 may be 0.5 times the frequency of the signal S1. For example, if the symbol of the signal S1 is a periodically repeated sequence [1 -1], the symbol of the signal output by the divider 47 may be a periodically repeated sequence [1 1 -1 -1].

[0050] The two input terminals of the mixer 48 can be respectively coupled to a high potential voltage source V DD and the output of the phase-locked loop circuit 41. The input of the phase shifter 49 can be coupled to the output of the phase-locked loop circuit 41. The two inputs of the mixer 50 can be coupled to the output of the divider 47 and the output of the phase shifter 49, respectively. The two inputs of the adder 51 can be coupled to the output of the mixer 48 and the output of the mixer 50, respectively. The output of the adder 51 can be coupled to a high-pass filter and an antenna to output a radio frequency signal.

[0051] Back to Figure 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.

[0052] In one embodiment, the processor 110 of the server 100 may perform pre-processing on the radar signal to obtain a processed signal. RX (t) as an example, first, the processor 110 may process the radar signal V RX (t) Perform in-phase and quadrature demodulation (IQ-demodulation) to obtain the received in-phase component I RX (t) and the received quadrature component Q RX (t), as shown in formula (4) and formula (5), where V I Represents the corresponding V I(t) inherent DC bias, V Q Represents the corresponding V Q (t)’s inherent DC bias, A I represents the gain of the receiving channel corresponding to the in-phase component, A Q represents the gain of the receive channel corresponding to the quadrature component, and represents the local oscillator of the receiving circuit 212 and the radar signal V RX (t) The phase difference caused by the non-coherence between V I With V Q can be orthogonal to each other. For example, if V I is a periodically repeating sequence [1 1 1 1], then V Q It can be a periodically repeated sequence [1 -1 1 -1].

[0053]

[0054]

[0055] Next, the processor 110 may receive the in-phase component I RX (t) and V Q (t) performing a convolution operation, and performing a multiply-accumulate (MAC) operation on the result of the convolution operation to obtain an accumulated value I RX (n), as shown in formula (6), where T represents the time interval between symbol changes. For example, if V Q is the sequence [1 -1], then V Q The value of will change from "1" to "-1" after a time interval T. On the other hand, the processor 110 may receive the orthogonal component Q RX (t) and V Q (t) Perform a convolution operation and perform a product move-accumulate operation on the result of the convolution operation to obtain an accumulated value Q RX (n), as shown in formula (7).

[0056]

[0057]

[0058] Then, the processor 110 may receive the in-phase component I RX (t) and V Q The result of the convolution operation of (t) is subjected to a difference operation (e.g., a moving difference operation) to obtain a difference ΔI RX(n), as shown in formula (8). On the other hand, the processor 110 may receive the orthogonal component Q RX (t) and V Q The result of the convolution operation of (t) is subjected to a differential operation (e.g., a moving differential operation) to obtain a differential ΔQ RX (n), as shown in formula (9).

[0059]

[0060]

[0061] The processor 110 may calculate the difference ΔI RX (n) and the accumulated value Q RX (n), as shown in formula (10). The processor 110 can calculate the difference ΔQ RX (n) and the accumulated value I RX The processor 110 can process the formula (10), the formula (11) or the product thereof, the formula (12), to generate the processed signal PS1.

[0062]

[0063]

[0064]

[0065] As mentioned above, formula (10) or formula (11) is essentially the time-varying rate (or velocity) of the distance between the target and the radar. By accumulating formula (10) or accumulating formula (11) in time sequence, the relationship between the distance of the target relative to the radar and time can be obtained. The value obtained after the accumulation can be used as the processing signal PS1. In addition, the square root of the absolute value of formula (12) can also be accumulated in time sequence to obtain the relationship between the distance of the target relative to the radar and time. Using formula (12), A in formula (10) or formula (11) can be further converted to 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 orthogonal component) is removed to solve A I The rate of change (i.e.: A I The degree of change over time) and A Q The rate of change (i.e.: A Q The problem of inconsistency in the degree of change over time.

[0066] The processor 110 may generate processing signals PS2 , PS3 , and PS4 corresponding to the radars 220 , 230 , and 240 , respectively, in a manner similar to the processing signal PS1 corresponding to the radar 210 .

[0067] In one embodiment, during the period when the processor 110 performs pre-processing on the radar signal, the processor 110 may perform low-pass filtering on the radar signal to filter out signals unrelated to heartbeat or breathing (e.g., noise caused by vibration of the power vehicle 500), thereby obtaining a processed signal. For example, the processor 110 may apply a 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 the following design parameters: 3dB frequency = 5 Hz; zero frequency = 12 Hz; and sampling frequency = 12*X Hz.

[0068] In one embodiment, the receiving circuit of the radar may perform pre-processing on the radar signal to obtain a processed signal. Taking radar 210 as an example, Figure 5 According to an embodiment of the present invention, a circuit diagram of a receiving circuit 212 of a radar 210 is shown. The receiving circuit 212 can receive a radar signal V RX (t) performing pre-processing to obtain a processed signal. The receiving circuit 212 may include a phase-locked loop circuit 61, a 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.

[0069] The input terminal of the phase-locked loop circuit 61 can be coupled to a signal source for receiving a periodic oscillating signal S2. In one embodiment, the sign of the signal S2 can be related to the RF signal V TX The sign of the transmitted quadrature component of (t) (i.e.: V Q ). The input end of the divider 62 may be coupled to the output end of the phase-locked loop circuit 61, and the output end of the divider 62 may be coupled to the input end 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.

[0070] The two input terminals of the mixer 63 can be coupled to the output terminal of the phase-locked loop circuit 61 and the radar signal V RXThe output of the mixer 63 can be coupled to the input of the low-pass filter 66. The input of the phase shifter 64 can be coupled to the output of the phase-locked loop circuit 61. The two inputs of the mixer 65 can be coupled to the radar signal V RX (t) and the output of the phase shifter 64. The output of the mixer 65 can be coupled to the input of the low-pass filter 67. RX (t) After passing through the mixer 63 and the low-pass filter 66, the radar signal V RX (t) can be transformed into the received in-phase component I as shown in formula (4): RX (t). On the other hand, in the radar signal V RX (t) After passing through the mixer 65 and the low-pass filter 67, the radar signal V RX (t) can be transformed into the received quadrature component Q as shown in formula (5): RX (t).

[0071] The two input terminals of the mixer 68 can be coupled to the output terminal of the low-pass filter 66 and the signal source of the signal S2, respectively, and the output terminal of the mixer 68 can be coupled to the input terminal of the analog-to-digital converter 70. The input terminal of the shift register 72 can be coupled to the output terminal of the analog-to-digital converter 70, and the multiple output terminals of the shift register 72 can be coupled to the adder 74 to output parallel data to the adder 74. The receiving circuit 212 can receive the in-phase component I through the mixer 68. RX (t) and V Q After the convolution operation result is converted into a digital signal by the analog-to-digital converter 70, the shift register 72 and the adder 74 can perform a product shift accumulation operation on the operation result to obtain an accumulated value I as shown in formula (6): RX (n). On the other hand, the two input terminals of the subtractor 76 can be respectively coupled to the input terminal of the shift register 72 and the final output terminal of the shift register 72 (for example, the output of the last stage of the shift register 72, wherein the data stored in the last stage is the data in the shift register 72 that is delayed the longest before being output). The receiving circuit 212 can perform a differential operation on the operation result of the convolution operation through the subtractor 76 to obtain the differential ΔI shown in formula (8): RX (n).

[0072] On the other hand, two input terminals of the mixer 69 can be coupled to the output terminal of the low-pass filter 66 and the signal source of the signal S2, respectively, and the output terminal of the mixer 69 can be coupled to the input terminal of the analog-to-digital converter 71. The input terminal of the shift register 73 can be coupled to the output terminal of the analog-to-digital converter 71, and the multiple output terminals of the shift register 73 can be coupled to the adder 75 to output parallel data to the adder 75. The receiving circuit 212 can receive the orthogonal component Q through the mixer 69. RX (t) and V Q After the convolution operation result is converted into a digital signal by the analog-to-digital converter 71, the shift register 73 and the adder 75 can perform a product shift accumulation operation on the operation result to obtain the accumulated value Q as shown in formula (7): RX (n). On the other hand, the two input terminals of the subtractor 77 can be respectively coupled to the input terminal of the shift register 73 and the final output terminal of the shift register 73 (for example, the output of the last stage of the shift register 73, wherein the data stored in the last stage is the data in the shift register 73 that is delayed the longest before being output). The receiving circuit 212 can perform a differential operation on the operation result of the convolution operation through the subtractor 77 to obtain a differential ΔQ as shown in formula (9): RX The period of signal S2 may be an integer multiple of the sampling period of analog-to-digital converter 70 (or 71), and the number of bits of shift registers 72 and 73 may be an integer multiple of the ratio of the period of signal S2 to the sampling period of analog-to-digital converter 70 (or 71).

[0073] In obtaining the accumulated value I RX (n), accumulated value Q RX (n), difference ΔI RX (n) and the difference ΔQ RX (n), the receiving circuit 212 (or the server 100) may further calculate the accumulated value I RX (n), accumulated value Q RX (n), difference ΔI RX (n) and the difference ΔQ RX (n) Generates the processed signal PS1 of the radar 210 as shown in formula (12).

[0074] Back to Figure 3In step S303, the processor 110 may determine whether the power component of the processing signal PS1 of the radar 210 is greater than a threshold value, wherein the power component may include the power of the processing signal PS1 within a specific frequency range (e.g., a frequency range associated with vital signs such as breathing or heartbeat: 0.25 Hz to 3 Hz). If the power component is greater than the threshold value, it means that a target 311 is sitting on the seat 31 detected by the radar 210, and the processor 110 may execute step S305. If the power component is less than or equal to the threshold value, it means that no target is sitting on the seat 31 detected by the radar 210, and the processor 110 may execute step S304. For example, the processor 110 may perform a time-frequency conversion on the processing signal PS1 (e.g., perform a Fourier transform on the processing signal) to generate a spectrum of the processing signal PS1, and obtain a power component corresponding to the specific frequency range from the spectrum. The processor 110 may determine whether the power component of the processing signal PS1 is greater than the threshold value. If the processed signal PS1 is greater than the threshold, it means 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 means that there is no target on the seat 31 detected by the radar 210. Based on a similar method, 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.

[0075] In step S304 , the processor 110 may determine that there is no target on the seat 31 detected by the radar 210 and generate a detection result. The processor 110 may output the detection result through the transceiver 130 .

[0076] In step S305, the processor 110 may determine whether a reference signal that can be used as the processing signal PS1 exists. If the reference signal exists, the process proceeds to step S306. If the reference signal does not exist, the process proceeds to step S307. The reference signal, for example, includes processing signals corresponding to other radars (other radars other than the radar 210, such as the radar 220, the radar 230, or the radar 240) and whose power components are less than or equal to the threshold. Taking FIG. 2 as an example, since there is a target 321 on the seat 32 detected by the radar 220, the power component of the processing signal PS2 corresponding to the radar 220 will be greater than the threshold. On the other hand, since there is no target on the seat 33 detected by the radar 230 or the seat 34 detected by the radar 240, the power component of the processing signal PS3 corresponding to the radar 230 or the power component of the processing signal PS4 corresponding to the radar 240 will be less than or equal to the threshold. Accordingly, the processor 110 may determine that the processing signal PS3 or the processing signal PS4 can be used as a reference signal for the processing signal PS1, and the processing signal PS2 cannot be used as a reference signal for the processing signal PS1. If the seat 32 , the seat 33 , and the seat 34 are all occupied by the target, the processor 110 may determine that the reference signal of the processing signal PS1 does not exist.

[0077] In step S306, the processor 110 may subtract a 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, wherein the vital sign may include a time-varying signal indicating a position change of the target 311 (e.g., movement of the chest of the target 311). The processor 110 may output the vital sign through the transceiver 130.

[0078] In step S307, the processor 110 may obtain the life sign corresponding to the target 311 detected by the radar 210 according to the lookup table. The processor 110 may output the life sign through the transceiver 130.

[0079] Specifically, the storage medium 120 may pre-store a lookup table corresponding to the power vehicle 500, wherein the lookup table may record the mapping relationship between the engine speed and the vibration frequency. For example, the lookup table may record "when the engine speed of the power vehicle 500 is 600 to 1200 revolutions per minute (RPM), the vibration frequency of the power vehicle 500 is 10 to 20 Hz". The processor 110 may be connected to the power vehicle 500 through the transceiver 130 to obtain dashboard information, wherein the dashboard information may include the engine speed of the power vehicle 500. The processor 110 may query the lookup table in the storage medium 120 according to the dashboard information to obtain the vibration frequency of the power vehicle 500. After obtaining the vibration frequency, the processor 110 may process the processing signal PS1 of the radar 210 according to the vibration frequency to obtain the vital signs of the target 311. For example, the processor 110 may apply a notch filter, a lowpass filter or other digital signal processing filter (DSP filter) to the processing signal PS1 to filter out the vibration frequency in the processing signal PS1, thereby obtaining the vital signs of the target 311, wherein the notch frequency of the digital signal processing filter may be an integer multiple of the vibration frequency.

[0080] In one embodiment, the RF signals transmitted by different radars (eg, radars 210 , 220 , 230 , and 240 ) are orthogonal frequency division multiplexing (OFDM) signals.

[0081] Figure 6 According to an embodiment of the present invention, a flow chart of a method for detecting life signs is shown, wherein the detection method is applicable to a power vehicle and can be performed as follows: Figure 1 The detection system 10 shown is implemented. In step S601, a first radio frequency signal is transmitted by a first radar, and a first radar signal corresponding to the first radio frequency signal is received, wherein the first radio frequency signal includes a first transmitted in-phase component and a first transmitted quadrature component. In step S602, in-phase and 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 the first received in-phase component and a first symbol corresponding to the first transmitted quadrature component, and a first product moving and adding operation is performed on the first result of the first convolution operation to obtain a first accumulated value. In step S604, a second convolution operation is performed on the first received quadrature component and a first symbol corresponding to the first transmitted quadrature component, and a second product moving and adding operation is performed on the second result of the second convolution operation to obtain a second accumulated value. In step S605, a first processed signal is generated according to the first accumulated value and the second accumulated value. In step S606, a life sign corresponding to the first radar is generated according to the first processed signal, and the life sign is output, wherein the first symbol of the first transmitted orthogonal component is orthogonal to the transmitted in-phase symbol of the first transmitted in-phase component, and the first symbol is a symbol with an average value of zero.

[0082] In summary, the detection system of the present invention can detect the seats of the power vehicle through the radio frequency signal transmitted by the radar to obtain the detection results. The transmission circuit of the radar can use two orthogonal symbols to generate the transmitted in-phase component and the transmitted orthogonal component of the radio frequency signal. The receiving circuit of the radar can use the sign of the transmitted orthogonal component to perform steps including convolution operation and product move accumulation operation to process the radar signal, so as to obtain the processed signal. If there are other radars in the power vehicle that have obtained the detection results that can be used as reference signals, the detection system can obtain the vital signs of the subject by comparing the processed signal and the reference signal. On the other hand, the detection system can also obtain the vital signs according to the lookup table based on the dashboard information of the power vehicle. Compared with the traditional non-contact vital signs monitoring system, the detection system of the present invention can accurately measure the vital signs of the subject in an unstable environment.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vital sign detection system, suitable for a power vehicle, characterized in that: The detection system comprises: First Radar; and A server is communicatively connected to the first radar and is configured to perform: transmitting a first radio frequency signal through the first radar, and receiving a first radar signal corresponding to the first radio frequency signal, wherein the first radio frequency signal includes 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 the first received in-phase component and a first symbol corresponding to the first transmitted quadrature component, and performing a first product-shift-accumulate operation on a first result of the first convolution operation to obtain a first accumulated value; performing a second convolution operation on the first received orthogonal component and the first symbol corresponding to the first transmitted orthogonal component, and performing a second product-shift-accumulate operation on a second result of the second convolution operation to obtain a second accumulated value; generating a first processing signal according to the first accumulated value and the second accumulated value; and A life sign corresponding to the first radar is generated according to the first processed signal and output, wherein the first symbol of the first transmitted orthogonal component is orthogonal to the transmitted in-phase symbol of the first transmitted in-phase component and the first symbol is a symbol with an average value of zero.

2. The detection system according to claim 1, further comprising: A second radar is communicatively connected to the server, wherein the server is further configured to perform: transmitting a second radio frequency signal through 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; as well as The vital sign is generated according to the first processed signal and the second processed signal.

3. The detection system of claim 2, wherein the server is further configured to perform: 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 less than or equal to the threshold, the second processed signal is subtracted from the first processed signal to obtain the life sign corresponding to the first radar.

4. The detection system of claim 1, wherein the server is further configured to perform: Communicating to the power vehicle to obtain dashboard information, and querying a lookup table according to the dashboard information to obtain a vibration frequency; and The first processed signal is processed according to the vibration frequency to obtain the vital sign.

5. The detection system of claim 4, wherein the instrument panel information includes engine speed. 6 . The detection system of claim 2 , wherein the first symbol of the first transmit quadrature component of the first RF signal and the second symbol of the second transmit quadrature component of the second RF signal are orthogonal to each other. 7 . The detection system according to claim 2 , wherein the first RF signal and the second RF signal are orthogonal frequency division multiplexing signals.

8. The detection system of claim 1, wherein the server is further configured to perform: Performing a first difference operation according to the first result to obtain a first difference; and A ratio of the first difference to the second accumulated value is calculated to generate the first processed signal.

9. The detection system of claim 1, wherein the server is further configured to perform: A low-pass filter is performed on the first radar signal to obtain the first processed signal.

10. The detection system of claim 1, wherein the vital signs include time-varying signals indicative of position changes.

11. A method for detecting life signs, applicable to a power vehicle, characterized in that: The detection method comprises: transmitting a first radio frequency signal through a first radar, and receiving a first radar signal corresponding to the first radio frequency signal, wherein the first radio frequency signal includes 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 the first received in-phase component and a first symbol corresponding to the first transmitted quadrature component, and performing a first product-shift-accumulate operation on a first result of the first convolution operation to obtain a first accumulated value; performing a second convolution operation on the first received orthogonal component and the first symbol corresponding to the first transmitted orthogonal component, and performing a second product-shift-accumulate operation on a second result of the second convolution operation to obtain a second accumulated value; generating a first processing signal according to the first accumulated value and the second accumulated value; and A life sign corresponding to the first radar is generated according to the first processed signal and output, wherein the first symbol of the first transmitted orthogonal component is orthogonal to the transmitted in-phase symbol of the first transmitted in-phase component and the first symbol is a symbol with an average value of zero.

12. The detection method according to claim 11, further comprising: 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; as well as The vital sign is generated according to the first processed signal and the second processed signal.

13. The detection method according to claim 12, further comprising: 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 less than or equal to the threshold, the second processed signal is subtracted from the first processed signal to obtain the life sign corresponding to the first radar.

14. The detection method according to claim 11, further comprising: Obtaining instrument panel information from the power vehicle, and querying a lookup table according to the instrument panel information to obtain a vibration frequency; as well as The first processed signal is processed according to the vibration frequency to obtain the vital sign. The detection method according to claim 14 , wherein the instrument panel information includes engine speed. 16 . The detection method according to claim 12 , wherein the first symbol of the first transmitted orthogonal component of the first RF signal and the second symbol of the second transmitted orthogonal component of the second RF signal are orthogonal to each other. 17 . The detection method according to claim 12 , wherein the first radio frequency signal and the second radio frequency signal are orthogonal frequency division multiplexing signals.

18. The detection method according to claim 11, wherein the step of generating the first processing signal according to the first accumulated value and the second accumulated value comprises: performing a first difference operation according to the first result to obtain a first difference; as well as A ratio of the first difference to the second accumulated value is calculated to generate the first processed signal.

19. The detection method according to claim 11, further comprising: A low-pass filter is performed on the first laser signal to obtain the first processed signal.

20. The detection method of claim 11, wherein the vital signs include time-varying signals indicating position changes.

Images