JP7790153B2 - Biological information detection device - Google Patents

Description

An embodiment of the present invention relates to a biological information detection device.

Driver monitoring systems and the like use technology to detect biometric information (e.g., heart rate, heartbeat interval, etc.) of occupants of a moving object (vehicle, etc.) based on TOF (Time of Flight) information, Doppler shift information, etc. acquired by sensors that transmit and receive FMCW (Frequency Modulated Continuous Wave) radio waves.

Japanese Patent Application Laid-Open No. 2019-168379

In systems like the one described above, to detect biometric information with high accuracy, it is necessary to remove vibration components caused by the vibration of the moving object from the data acquired by the sensor. The vibration components that need to be removed include high-speed vibration components corresponding to relatively fast vibration velocities and low-speed vibration components corresponding to relatively slow vibration velocities. In order to accurately detect and remove the low-speed vibration components, the sensor needs to have high resolution, which increases costs.

Therefore, one of the problems that this invention aims to solve is to provide a biological information detection device that can detect biological information with high accuracy while suppressing increases in costs.

A biometric information detection device according to an embodiment of the present invention includes a sensor that transmits frequency-modulated electromagnetic waves as transmission waves into a room of a moving object and receives reflected waves generated when the transmission waves are reflected by an object present in the room, a position information generation unit that generates position information indicating the position of the object in the room based on the reflected waves, a velocity information generation unit that generates velocity information indicating the velocity of the object based on the reflected waves, a person detection unit that detects a person present in the room based on the position information and the velocity information, a correction unit that performs a correction process to remove vibration components corresponding to vibrations of the moving object from the velocity information corresponding to the movement of the person, and a biometric information generation unit that generates biometric information of the person based on high-speed velocity information that has been corrected and corresponds to a velocity greater than or equal to a predetermined velocity. The correction process is performed based on the difference between a complex velocity distribution, which is a velocity distribution based on the complex intensity of the reflected wave included in the voxel values of voxels that constitute a labeling area determined to be a person in a voxel diagram showing the arrangement of objects in the room, and an absolute velocity distribution, which is a velocity distribution based on the absolute value of the intensity of the reflected wave.

Vibration components above a certain speed can be removed relatively accurately through correction processing. Therefore, by using the above configuration, highly accurate biometric information can be generated using high-speed range speed information from which vibration components have been accurately removed.

The predetermined speed may also be 10 km/h.

This allows for both cost reduction and improved accuracy in detecting biometric information.

The biometric information may also include heart rate information regarding the person's heart rate.

This makes it possible to obtain highly accurate heart rate information of passengers that can be used to control the vehicle.

FIG. 1 is a diagram illustrating an example of a configuration of a vehicle according to an embodiment. FIG. 2 is a block diagram illustrating an example of a functional configuration of the sensor and the control device according to the embodiment. FIG. 3 is a diagram showing an outline of signal processing by the FMCW method according to the embodiment. FIG. 4 is a flowchart illustrating an example of processing performed by the biological information detection device according to the embodiment. FIG. 5 is a flowchart illustrating an example of a process for generating high speed range speed information according to the embodiment.

The following describes exemplary embodiments of the present invention. The configurations of the embodiments described below, as well as the actions, results, and advantages achieved by such configurations, are merely examples. The present invention can be realized using configurations other than those disclosed in the following embodiments, and it is possible to obtain at least one of the various advantages and derivative advantages based on the basic configuration.

Figure 1 is a diagram showing an example of the configuration of a vehicle C according to an embodiment. A sensor 2 and a control device 3 constituting a biometric information detection device 1 are arranged inside the vehicle C (an example of a moving body). The sensor 2 according to this embodiment is installed on the ceiling of the vehicle. The control device 3 according to this embodiment is installed inside the dashboard at the front end of the vehicle. However, the installation locations of the sensor 2 and the control device 3 are not limited to this.

Figure 1 illustrates an example of a state in which an occupant M (person) is sitting in a seat S. Below, we will explain how the biometric information detection device 1 detects the presence of occupant M and detects the biometric information of occupant M. Note that while Figure 1 illustrates an example in which occupant M is sitting in the rear seat, the position of occupant M to be detected is not limited to this. For example, an occupant sitting in the driver's seat or passenger seat may also be the detection target.

Figure 2 is a block diagram showing an example of the functional configuration of the sensor 2 and control device 3 of this embodiment. The sensor 2 includes a transmitter 21 and a receiver 22.

The transmitter 21 transmits (irradiates) frequency-modulated electromagnetic waves as transmission waves over a wide area within the interior of vehicle C. The receiver 22 receives reflected waves generated when the transmission waves are reflected by objects present within the interior.

The control device 3 is configured, for example, by an MCU (Micro Controller Unit) having an integrated circuit equipped with a hardware processor, memory, etc. The control device 3 includes an ADC (Analog-to-Digital Converter) 31, a processing unit 32, and a storage unit 33.

The ADC 31 converts the analog signal acquired by the receiving unit 22 of the sensor 2 into a digital signal and outputs it to the processing unit 32.

The storage unit 33 is, for example, a storage device such as RAM (Random Access Memory), ROM (Read Only Memory), SSD (Solid State Drive), or HDD (Hard Disk Drive). The storage unit 33 stores programs executed by the processing unit 32, data required for program execution, data generated by program execution, etc. In this embodiment, the storage unit 33 stores setting information 331, position information 332, speed information 333, biometric information 334, etc.

The setting information 331 includes various thresholds for realizing the functions of the biometric information detection device 1. The thresholds may be, for example, a threshold for determining whether an object present in a room is a living or non-living thing, a threshold for determining whether a living thing is a person, a threshold for determining whether a person is an adult or a child, a threshold for detecting a person's biometric signal, etc.

Position information 332 indicates the position of an object present in the room, and is generated by the position information generator 321 based on the intensity distribution of reflected waves in the room. The intensity distribution is information that indicates the correspondence between the position of the reflection source (object) in three-dimensional space (the room of vehicle C) and the intensity of the reflected waves.

Speed information 333 is information indicating the speed of an object present in the room, and is generated by the speed information generator 322 based on the Doppler shift of the reflected wave, etc. Speed information 333 may also include information indicating the direction of movement of the object.

Biometric information 334 is information relating to the body and mind of occupant M present in the cabin, and is generated by the biometric information generation unit 325 based on speed information 333 and the like corresponding to occupant M. In this embodiment, the biometric information includes information relating to the heartbeat of occupant M (e.g., heartbeat interval, heart rate, etc.). The biometric information can be detected based on speed information 333 and the like corresponding to the movement of a specific part of occupant M (e.g., chest, back, etc.). The biometric information may also include information indicating the physical condition, mental state, etc. inferred from the information relating to the heartbeat.

Here, we will provide an overview of signal processing using the FMCW method. Figure 3 is a diagram showing an overview of signal processing using the FMCW method in an embodiment. First, as shown in state (A), FMCW-modulated electromagnetic waves are transmitted from the transmitter 21 of sensor 2 into the interior of vehicle C. Then, the receiver 22 of sensor 2 receives the reflected waves.

Next, as shown in state (B), a voxel diagram showing the arrangement (including position, size, shape, etc.) of objects in three-dimensional space (the interior) is created based on the intensity distribution of the reflected waves within the interior. Each voxel constituting the voxel diagram has a voxel value including coordinate values (x, y, z) indicating its position in three-dimensional space (a Cartesian coordinate system consisting of the x-, y-, and z-axes) and the intensity of the reflected waves (complex number). The voxel diagram includes a labeling area D indicating the arrangement of objects present in the interior (occupant M, seat S, luggage, other vehicle structures, etc.). The voxel diagram is updated as the reflected wave information acquired by sensor 2 is updated. Information regarding the position and speed of objects can be obtained by analyzing changes in this voxel diagram. For example, by performing FFT (Fast Fourier Transform) analysis on the difference between adjacent frames of the voxel diagram, it is possible to calculate the Doppler shift of the reflected waves and the speed distribution indicating the relationship between speed and the strength of the reflected waves.

Next, as shown in state (C), occupant M present in the vehicle cabin is detected based on the analysis results of the voxel values of the voxels that make up labeling area D. For example, of the multiple objects present in the vehicle cabin, an object that meets certain conditions (size, shape, speed, etc.) can be determined to be occupant M. In addition, biometric information of occupant M can be detected based on the movement of a certain part (e.g., chest, back, etc.) of the object determined to be occupant M.

The processing performed by the processing unit 32 is described below with reference to Figure 2.

The processing unit 32 is configured, for example, by a hardware processor such as a CPU (Central Processing Unit). The processing unit 32 reads programs stored in the storage unit 33 and executes calculations. The processing unit 32 includes, as functional units, a position information generation unit 321, a speed information generation unit 322, a person detection unit 323, a correction unit 324, and a biometric information generation unit 325. Note that some or all of the units 321 to 325 may be configured by hardware such as circuits including an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

The position information generation unit 321 generates indoor position information 332 based on information about reflected waves (reflected wave information) acquired from the ADC 31 and stores it in the storage unit 33. The position information can be generated, for example, based on the analysis results of the voxel diagram described above.

The velocity information generation unit 322 generates velocity information 333 indicating the velocity of objects present in the room based on the reflected wave information acquired from the ADC 31, and stores the velocity information 333 in the memory unit 33. The velocity information 333 can be generated, for example, based on the analysis results of the voxel diagram described above.

The person detection unit 323 detects an occupant M present in the cabin of the vehicle C based on setting information 331, position information 332, speed information 333, etc. The person detection unit 323 may also determine the type of occupant M (e.g., adult, child, etc.).

The correction unit 324 performs correction processing to remove vibration components corresponding to the vibration of the vehicle C from the velocity information 333 corresponding to the movement of the occupant M. The correction processing in this embodiment is performed based on a velocity distribution that indicates the relationship between the velocity of the occupant M and the intensity of the reflected wave from the occupant M. The correction processing can be performed, for example, based on the difference between a complex velocity distribution, which is a velocity distribution based on the complex intensity of the reflected wave contained in the voxel values of the voxels that make up the labeling region D determined to be that of the occupant M in a voxel diagram that indicates the arrangement of objects present in the cabin, and an absolute velocity distribution, which is a velocity distribution based on the absolute value of the intensity of the reflected wave.

The biometric information generation unit 325 generates biometric information 324 of occupant M based on the high-speed range speed information, which has been corrected and is speed information corresponding to speeds equal to or greater than a predetermined speed. The predetermined speed is based on the resolution of sensor 2 and can be set lower the higher the resolution of sensor 2. The predetermined speed can be, for example, 10 km/h. The generated biometric information 324 is stored in the memory unit 33.

Figure 4 is a flowchart showing an example of processing by the biological information detection device 1 of this embodiment. When reflected wave information from within the vehicle C is acquired by driving the sensor 2 (S101), the position information generation unit 321 generates position information 332 indicating the position of an object within the room based on the intensity distribution of the reflected wave (S102), and the speed information generation unit 322 generates speed information 333 indicating the speed of the object based on the Doppler shift of the reflected wave (S103).

The person detection unit 323 determines whether or not occupant M is present in the cabin of vehicle C based on the position information 332 and speed information 333 (S104). If occupant M is not present (S104: No), this routine ends. If occupant M is present (S104: Yes), the correction unit 324 performs correction processing on the speed information 333 of occupant M (S105). The biometric information generation unit 325 generates biometric information based on the high-speed range speed information that has been corrected and is speed information corresponding to a speed equal to or greater than a predetermined speed (S106).

In the high-speed range above a certain speed, vibration components can be removed relatively accurately even if the resolution of sensor 2 is relatively low. Therefore, by performing the above processing, highly accurate biometric information can be generated using high-speed range speed information from which vibration components have been accurately removed.

Figure 5 is a flowchart showing an example of the processing performed when generating high-speed range speed information in this embodiment. First, voxel values for the region corresponding to occupant M are obtained from a voxel diagram such as that shown in Figure 3 (S201). These voxel values include values (x, y, z) indicating a position in three-dimensional space (orthogonal coordinate system) and the intensity (complex number) of the reflected wave at that position.

Then, FFT analysis is performed on the time series changes (difference between adjacent frames) in the intensity (complex number) of the acquired reflected wave to calculate a complex velocity distribution showing the relationship between velocity and complex intensity (S202). Furthermore, FFT analysis is performed on the time series changes in the absolute value of the intensity of the acquired reflected wave to calculate an absolute velocity distribution showing the relationship between velocity and the absolute value of intensity (S203).

Then, the difference between the complex velocity distribution and the absolute velocity distribution is calculated in the speed range of 10 km/h (an example of a predetermined speed) or higher (S204). Then, high-speed range speed information is generated by performing an inverse FFT analysis on this difference (S205).

According to the above embodiment, biological information is generated using high-speed speed information from which the vibration components of the vehicle C have been accurately removed. This allows biological information to be detected with high accuracy without incurring additional costs, such as by using a sensor 2 with high resolution.

The program executed by the control device 3 may be provided as a computer program product stored in an installable or executable file format on a computer-readable storage medium such as a CD-ROM, CD-R, memory card, DVD (Digital Versatile Disk), or flexible disk (FD). The program may also be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. The program may also be provided or distributed via a network such as the Internet.

The above describes an embodiment of the present invention, but the above embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

1...Biometric information detection device, 2...Sensor, 3...Control device, 21...Transmitter, 22...Receiver, 31...ADC, 32...Processor, 33...Memory unit, 321...Position information generator, 322...Speed information generator, 323...Person detector, 324...Correction unit, 325...Biometric information generator, 331...Setting information, 332...Position information, 333...Speed information, 334...Biometric information, C...Vehicle, D...Labeling area, M...Occupant, S...Seat

Claims (3)

a sensor that transmits a frequency-modulated electromagnetic wave as a transmission wave into a room of the mobile body and receives a reflected wave generated when the transmission wave is reflected by an object present in the room;
a position information generating unit that generates position information indicating a position of the object in the room based on the reflected wave;
a velocity information generating unit that generates velocity information indicating the velocity of the object based on the reflected wave;
a person detection unit that detects a person present in the room based on the position information and the velocity information;
a correction unit that performs correction processing to remove a vibration component corresponding to the vibration of the moving object from the velocity information corresponding to the movement of the person;
a biometric information generating unit that generates biometric information of the person based on high speed range speed information that has been subjected to the correction process and corresponds to a speed equal to or greater than a predetermined speed;
Equipped with
the correction process is performed based on a difference between a complex velocity distribution, which is a velocity distribution based on the complex intensity of the reflected wave included in voxel values of voxels that constitute a labeling region determined to be the person in a voxel diagram that shows the arrangement of the object in the room, and an absolute velocity distribution, which is a velocity distribution based on the absolute value of the intensity of the reflected wave.
Biometric information detection device. The predetermined speed is 10 km/h.
The biological information detection device according to claim 1 . The biological information includes heart rate information regarding the heart rate of the person.
3. The biological information detecting device according to claim 1.