Method and device for determining the pulse rate

Abstract

Method for determining a quantity representing the pulse rate of a living being, in which To determine the quantity representing the pulse rate, the temporal change of at least one location on the skin surface of the living being is determined and used by means of remote sensing without contact with a sensor that can be felt by the living being, wherein the change in a distance of the location of the skin surface to at least one second location is determined and used to determine the temporal change of the location of the skin surface, wherein the determination of the distance of the location of the skin surface to at least one second location is carried out within an inertial system, where to determine the temporal change of the location of the skin surface, the change in the position of the location of the main surface, those locations of the skin surface are used which are covered, wherein a time-of-flight method is used to determine the distance, characterized in that an acoustic signal is used to carry out the runtime procedure and that information on the driving behaviour and / or the vehicle condition is used to check the plausibility of the value representing the heart rate and that this information is taken from systems for vehicle condition assessment and / or systems for vehicle dynamics control, in particular an electronic stability program.

Description

State of the art

[0001] State-of-the-art methods are known in which physiological parameters are determined using photoplethysmography via remote sensing. Using camera images, remote sensing allows measurements of volume changes and thus the determination of cardiac activity. For example, DE102006026126A1 uses optical transmission and reflection sensors to determine blood pressure.

[0002] DE 102 59 522 A1 describes a method for sensing information about the position and / or movements of the body of a living being or a body part within the body, particularly for use in a motor vehicle. DE 10 2005 020 847 A1 describes a method for the contactless recording of biometric characteristics and vital functions of passengers in a motor vehicle, particularly heart rate and respiratory activity. DE 10 2009 053 407 A1 describes a method for continuously monitoring the medical condition of a vehicle occupant. DE 10 2008 004 523 A1 describes a device for the non-invasive, dynamic measurement of a person's chest activity.DE 11 2007 002 169 T5 describes a heartbeat detection device comprising a signal processing device that performs a frequency analysis on an output signal of a piezoelectric sensor provided on a seat, and a determining device that determines, based on a result of the frequency analysis of the signal processing device, that the signal component includes a seated person's vibration waveform indicating that a person is sitting on the seat.

[0003] A non-invasive polygraph technology based on optical analysis is known from US 7 831 061 B1. Disclosure of the invention

[0004] The invention is based on a method and a device for determining a quantity representing the pulse rate of a living being. The quantity is determined by remote sensing. The pulse rate is the mechanical effect of the living being's heartbeat per unit of time.

[0005] The essence of the invention is that the temporal change of at least one location on the skin surface of the living being is determined and used to determine the quantity representing the pulse rate.

[0006] The background of the invention is to determine the pulse rate of a living being without establishing contact with a sensor that the living being can feel. Furthermore, movement restrictions associated with determining the pulse rate should be avoided as much as possible. Since perceptible contact of the living being with a sensor can lead to a reduction in comfort and / or safety, contact that is not perceptible to the living being represents a gain in comfort and safety. Furthermore, determining the pulse rate based on the change in the location of a part of the skin surface represents a very precise measure for determining the volume change and thus for determining the pulse rate.

[0007] Since the measurement of the temporal change of a location on the skin surface can be carried out very precisely, such measuring methods have the advantage of higher accuracy compared to conventional photoplethysmographic methods.

[0008] Advantageously, the quantity representing the pulse rate is subjected to an analysis, in particular a frequency analysis. This has the advantage of distinguishing movements of the living being that are not caused by the pulse rate from those that are caused by the pulse rate.

[0009] According to the invention, information about the driving behavior and / or the vehicle condition is used to check the plausibility of the variable representing the pulse rate, and this information is preferably taken from systems for vehicle condition assessment and / or systems for vehicle dynamics control, in particular an electronic stability program.

[0010] To determine the value representing the pulse rate, the temporal change of at least one location at more than one site on the skin surface of the living being is preferably determined, used, and compared. Comparing the temporal change of at least one location on the skin surface, determined at multiple sites on the living being, leads to greater reliability in determining the pulse rate.

[0011] It is advantageous to determine the number of heartbeats of the living being per unit of time.

[0012] Preferably, the determination of the temporal change in the location of the skin surface is carried out in an inertial system.

[0013] To determine the temporal change in the location of the skin surface, the change in the position of the location of the main surface is advantageously used, such locations on the skin surface at which the pulse rate can be measured.

[0014] According to the invention, the change in the distance between the location of the skin surface and at least one second location is determined and used to determine the temporal change in the location of the skin surface. According to the invention, this determination is carried out within an inertial system, and a time-of-flight method is used to determine the distance. The measurement of the temporal change in the distance between the location of the skin surface and a second location is preferably carried out sequentially or continuously.

[0015] According to the invention, the change in the position of the main surface, including those covered skin surface locations, is used to determine the temporal change in the skin surface location. The prerequisite for using covered locations is that the covering material is a translucent and / or thin fabric, for example, eyeglass lenses or thin clothing fabric.

[0016] According to the invention, an acoustic signal is used to carry out the runtime method.

[0017] To carry out the time-of-flight method, an optical signal is advantageously used.

[0018] The optical signal is preferably monochromatic (e.g. a laser) or polychromatic.

[0019] The background to using a time-of-flight method, in particular a time-of-flight method carried out by means of an optical method, in particular a time-of-flight method carried out by means of a laser, is that such methods are known and can be carried out reliably under field conditions.

[0020] According to an advantageous embodiment, a device is used for determining a quantity representing the pulse rate of a living being, wherein the temporal change of at least one location on the skin surface of the living being is determined and used by means of remote sensing to determine the quantity representing the pulse rate.

[0021] Further embodiments of the invention are set out in the subclaims. Short description of the drawings

[0022] In the following section, the invention is explained using exemplary embodiments, from which further inventive features may emerge, but to which the scope of the invention is not limited. The embodiments are illustrated in the drawings.

[0023] It shows: Fig. 1 a representation of the process steps for determining the pulse rate; Fig. 2 a schematic representation of the method for determining the pulse rate using a transit time method. Embodiments of the invention

[0024] In Fig. Figure 1 shows the method steps for determining the pulse rate. The method is initiated by step 11. In step 22, the temporal change of at least one location on the organism's skin surface is determined by remote sensing and used to determine the pulse rate in step 33. The method is terminated by method step 44.

[0025] In Fig.Figure 2 schematically illustrates the method for determining pulse rate using a time-of-flight method. The method is shown at various points in time, denoted by t. The living being whose pulse rate is to be determined is denoted by L. The measuring device used to perform the time-of-flight method is denoted by M. Signals can be sent and received with M. S and S' denote the signals used for the time-of-flight method. The sampling intervals between times t and the minimum measurement sequence duration are selected such that the pulse rate of L can be determined.

[0026] At time t1, the signal emitted by M has reached SL. At time t2, S has returned from L to M. At time t3, a new signal S' emitted by M has reached L. At this time, the volume of a portion of L has changed. The change in volume is accompanied by a change in the location of the skin surface at this portion of L. The cause of the change in volume and thus also of the change in location on the skin surface is the pulse rate of L. At time t4, S' has returned from L to M. Since the speed at which S and S' are transmitted between M and L is known, the change in distance between L and M can be determined by measuring the time differences (t1 - t2) and (t3 - t4) and comparing these time differences. The change in distance is used to determine the changes in the location of the skin surface of L, and the determined change in location allows us to infer L's pulse rate.

[0027] Temporal changes in the location of L's skin surface that were not caused by L's pulse rate can be subjected to frequency analysis and evaluated and taken into account accordingly. Furthermore, to evaluate and take into account temporal changes in the location of L's skin surface that were not caused by the pulse rate, additional filtering methods and / or information about the driving behavior and / or the vehicle condition can be used. The information about the driving behavior and / or the vehicle condition can preferably be obtained from systems for vehicle condition assessment and / or systems for vehicle dynamics control, for example, an electronic stability program.

Claims

[1] Method for determining a quantity representing the pulse rate of a living being, in which To determine the quantity representing the pulse rate, the temporal change of at least one location on the skin surface of the living being is determined and used by means of remote sensing without contact with a sensor that can be felt by the living being, wherein the change in a distance of the location of the skin surface to at least one second location is determined and used to determine the temporal change of the location of the skin surface, wherein the determination of the distance of the location of the skin surface to at least one second location is carried out within an inertial system, where to determine the temporal change of the location of the skin surface, the change in the position of the location of the main surface, those locations of the skin surface are used which are covered, where a time-of-flight method is used to determine the distance, characterized by , that an acoustic signal is used to carry out the runtime procedure and that information on the driving behaviour and / or the vehicle condition is used to check the plausibility of the value representing the heart rate and that this information is taken from systems for vehicle condition assessment and / or systems for vehicle dynamics control, in particular an electronic stability program. [2] Method according to claim 1, characterized by that the quantity representing the pulse rate is subjected to an analysis, in particular a frequency analysis. [3] Method according to claim 1, characterized by that in order to determine the quantity representing the pulse rate, the temporal change of at least one location at more than one point on the skin surface of the living being is determined, used and compared. [4] Method according to claim 1, characterized by that the number of heart beats of the living being per unit of time is determined. [5] Method according to claim 1, characterized by that to determine the temporal change in the location of the skin surface, the change in the position of the location of the main surface in an inertial system is determined. [6] Method according to claim 1, characterized by that to determine the temporal change in the location of the skin surface, the change in the position of the location of the main surface, such locations of the skin surface are used where the pulse rate can be measured. [7] Method according to one of the preceding claims, characterized by that an optical signal is used to carry out the time-of-flight method. [8] Method according to claim 7, characterized by that the optical signal is monochromatic, for example a laser, or polychromatic in nature. [9] Device for determining a quantity representing the pulse rate of a living being, in which To determine the quantity representing the pulse rate, the temporal change of at least one location on the skin surface of the living being is determined and used by means of remote sensing without contact with a sensor that can be felt by the living being, wherein the change in a distance of the location of the skin surface to at least one second location is determined and used to determine the temporal change of the location of the skin surface, wherein the determination of the distance of the location of the skin surface to at least one second location is carried out within an inertial system, where to determine the temporal change of the location of the skin surface, the change in the position of the location of the main surface, those locations of the skin surface are used which are covered, where a time-of-flight method is used to determine the distance, characterized by , that an acoustic signal is used to carry out the runtime procedure and that information on the driving behaviour and / or the vehicle condition is used to check the plausibility of the value representing the heart rate and that this information is taken from systems for vehicle condition assessment and / or systems for vehicle dynamics control, in particular an electronic stability program.

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