JP2018051098A - Living body posture detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a posture state of a living body with an inexpensive structure.SOLUTION: An electrode part D is formed by covering surfaces of a first electrode 1 and a second electrode 2 with an insulation 3. A high frequency power source 4 is connected to the first electrode part 1 through a guide element 11 for forming a resonant circuit, and an ammeter 5 is connected to the second electrode 2. A relationship between a resonant frequency and a resonant ohmic value when a frequency from the high frequency power source 4 is swept and a current state indicating resonance is detected on the ammeter 5, is acquired. From the relationship, a posture (or, posture change) of a living body is determined based on a resonant ohmic value in a range where the resonant frequency and the resonant ohmic value are reduced or increased together.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a biological posture detection device.

  Recently, various sensors for detecting the relationship with a living body have been developed. Patent Literature 1 discloses a device that detects a heart rate and the like based on a change in distance between capacitance sensors. Japanese Patent Application Laid-Open No. 2004-133620 discloses a device that detects the presence or absence of an operation touch based on a change in capacitance. Patent Document 3 discloses a resonance circuit including an electrode portion having a structure in which the capacitance of the electrode portion is maximized, wherein the resistance value at the resonance point is the skin resistance of a living body.

JP, 2014-210127, A JP 2014-44225 A JP, 2015-110508, A

  Recently, it has become desirable to detect the posture state of a living body. For example, in a vehicle that performs automatic driving, it is desired to determine whether or not it is in a state that can cope with a case where the driver's posture is fast. Further, since the posture state of the driver also serves as an index indicating the driver state such as tension and fatigue, it is desired to detect the posture from such a viewpoint. In order to detect the posture of the living body, it is conceivable to use a camera that images the living body, but in this case, there is a problem in terms of cost.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a living body posture detecting apparatus capable of detecting the posture of a living body at a low cost.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1,
The electrode part is configured by covering the surfaces of the first electrode and the second electrode with an insulating material,
A high frequency power source is connected to the first electrode part via an inductive element for constituting a resonance circuit, while a current measuring means is connected to the second electrode,
A correlation acquisition unit that obtains a correlation between a resonance frequency and a resonance resistance value when a current state indicating resonance is detected by the current measurement unit by sweeping a frequency from the high-frequency power source;
Posture determination means for determining the posture of the living body based on the resonance resistance value in a range where both the resonance frequency and the resonance resistance value decrease or increase based on the correlation acquired by the correlation acquisition means;
It is supposed to be equipped with.

  According to the above solution, the resonance resistance value in a range where both the resonance frequency and the resonance resistance value decrease or increase together is a part where the body of the living body (for example, a car driver's buttocks or back) is grounded (for example, Since the region where the driver is in contact with the driver's seat is indicated, the posture state of the living body can be determined based on the resonance resistance value. Further, it is possible to detect the posture change and its frequency based on the change in the resonance resistance value in the above range (particularly, the change within a predetermined time). Then, the posture of the living body can be detected without using an imaging device such as an expensive camera.

A preferred mode based on the above solution is as described in claim 2 and the following. That is,
The posture determination means determines the contact state between the body of the living body and the ground part (corresponding to claim 2). In this case, the posture can be detected according to the grounding part in contact.

  The posture determining means determines a posture change of the living body based on a change amount of the resonance resistance value within a predetermined time (corresponding to claim 3). In this case, a change in posture can be detected.

  The first electrode and the second electrode are arranged so as to be along the entire circumference of the steering wheel of the automobile in a stacked relationship (corresponding to claim 4). In this case, the posture of the driver sitting on the driver's seat can be detected with high accuracy. Further, an increase in resistance can be suppressed as compared with the case where two electrodes are arranged in parallel.

  The first electrode and the second electrode are arranged along the entire circumference of the steering wheel of an automobile in a parallel relationship (corresponding to claim 5). In this case, it is preferable in detecting a wide range of information about the living body, such as detection of the contact area of the living body with respect to the electrode and detection of the presence or absence of perspiration.

The electrode part is provided on a steering wheel of an automobile,
Based on the posture determined by the posture determination means, further comprising a driver state determination means for determining the driver state;
(Corresponding to claim 6). In this case, the driver state can be known based on the determined posture.

It has a database that stores the relationship between the posture of the living body and the resonance resistance value,
The posture determination means determines the posture of the living body by comparing the resonance resistance value with the database;
(Corresponding to claim 7). In this case, the posture of the living body can be accurately detected using the database.

A database storing the relationship between the change in posture of the living body and the amount of change in the resonance resistance value within a predetermined time,
The posture determination means determines a change in posture of the living body by comparing the amount of change with the database;
This is done (corresponding to claim 8). In this case, a change in posture of the living body can be accurately detected using the database.

  Concentration estimation means for estimating the concentration level of the living body based on the frequency of the change in posture of the living body determined by the posture determination means is provided (corresponding to claim 9). In this case, the degree of concentration of the living body (for example, the driver of the vehicle) can be estimated.

  According to the present invention, the posture of a living body can be detected at a low cost.

The figure which shows the state which the fingertip has touched the electrode part in which the resonance circuit was incorporated. The characteristic view which shows the correlation of a resonance resistance value and a resonance frequency. The figure which shows the example which has arrange | positioned the electrode part with respect to the steering handle. The figure which shows the example of a control system of this invention. The figure which shows the example of control of the controller in FIG. The figure which shows the example which laminatedly arranged two electrodes, and is a figure corresponding to FIG. The flowchart which shows the example of control for determining a driver | operator state.

  In FIG. 1, 1 is a first electrode (transmission side electrode) and 2 is a second electrode (reception side electrode). The electrodes 1 and 2 are arranged in parallel in the embodiment, and the surface thereof is covered with an insulating material 3. The insulating material 3 is disposed across the electrodes 1 and 2. Although the insulating material 3 is shown in a thick state in FIG. 1, it is actually a thin film. The electrodes 1 and 2 and the insulating material 3 constitute an electrode part D.

  The first electrode 1 is connected to a high frequency power source 4. The high-frequency power supply 4 is configured such that the frequency can be changed (swept) in the range of 500 KHz to 4 MHz, for example. The second electrode 2 is connected to an ammeter 5 as current measuring means. In order to form a resonance circuit for the electrode part D, an induction element 11 (whose inductance is shown as L) is interposed between the first electrode 1 and the high-frequency power source 4.

  In FIG. 1, a human body as a living body (a driver of a car in the embodiment) is indicated by a symbol M, and a fingertip thereof is indicated by a symbol M1. FIG. 1 shows an equivalent circuit when the fingertip M1 is in contact with the electrode D (the insulating material 3). That is, R1 is a leakage resistance value between both electrodes 1 and 2, and Cm is a mutual capacitance between both electrodes 1 and 2. Cf is a capacitance between the fingertip M1 and the electrode 1 or 2 (the capacitance for the first electrode 1 and the capacitance for the second electrode 2 are shown as the same value Cf), Rf is skin resistance. In addition, skin resistance changes with contact areas.

  Furthermore, in the state where the fingertip M1 is in contact with the electrode D, a human body ground path that flows through the driver's body as the living body M is configured. That is, the living body M that is a driver of the automobile is in a state of being grounded to the vehicle body by sitting on the driver's seat. In this human body ground path, Rb is a human body resistance, and Cp is a human body capacitance.

  When the fingertip M1 is greatly separated from the insulating material 3 (for example, when separated by 30 cm or more), the skin resistance Rf and the human body ground are ignored. For this reason, the path through which the current from the high-frequency power source 4 flows is a path from the induction element 11 through the first electrode 1 to the second electrode 2 through the leakage resistor R1 and the mutual capacitance Cm. Such a current flow is indicated by a solid line in the figure.

  When the fingertip M1 is in contact with the insulating material 3, two circuit systems resulting from the living body M are generated. The first circuit system resulting from the living body M is a path involving the skin resistance Rf, and the current from the high-frequency power source 4 is the inductive element 11, the first electrode 1, the electrostatic capacitance Cf on the left side in the figure, and the skin resistance Rf. , A path to the second electrode 2 through the capacitance Cf on the right side in the figure. Such a current flow is indicated by a one-dot chain line in the figure.

  The second circuit system resulting from the living body M is a human body ground path, and the current from the high frequency power source 4 is the inductive element 11, the first electrode 1, the left side capacitance Cf, the human body resistance Rb, the human body static. This is a path through the capacitance Cb. Such a current flow is indicated by a broken line in the figure (a path that does not pass through the ammeter 5).

  Here, since the capacitance Cf is generated even in a state where the fingertip M1 is slightly separated from the insulating material 3 (a hover touch state where the fingertip M1 is not in contact but at a short distance), in addition to the flow shown by the solid line, A flow indicated by a broken line is generated. That is, when the fingertip M1 is gradually approached from the state of being largely separated from the electrode part D (the insulating material 3 thereof) and finally brought into contact with the electrode part D (the insulating material 3), "," State of solid line in FIG. 1 + state of broken line in FIG. 1 "," state of solid line in FIG. 1 + state of broken line in FIG. 1 + state of dashed line in FIG.

  Now, it is assumed that the fingertip M1 is gradually separated from the insulating material 3 and gradually brought closer to the insulating material 3 and finally strongly pressed against the insulating material 3. In this process of changing the position of the fingertip M1, the frequency of the high-frequency power source 4 is changed (swept), and the correlation between the resonance frequency and the resonance resistance value at that time is shown together in FIG. 2. The resonance is detected when the ammeter 5 detects the extreme value, the frequency at the time of resonance is the resonance frequency, and the resistance value at that time is the resonance resistance value (resonance resistance value is (Calculated based on the voltage generated by the high frequency power source 4 and the detected current by the ammeter 5)

  In FIG. 2, when the fingertip M1 is greatly separated from the insulating material 3, the initial resistance value at the time of resonance is the leak resistance R1, and the resonance frequency at this time is the initial resonance frequency. The point in time when the initial resistance value (= R1) is reached is indicated by symbol α in FIG.

  When the fingertip M1 is further moved closer to the insulating material 3 from the state in which the initial resistance value R1 is detected, a current flow indicated by a broken line in FIG. 1 is generated, and as a result, the current value detected by the ammeter 5 decreases accordingly. Thus, the resonance resistance value increases while the resonance frequency decreases. As described above, in a state where the resonance resistance value increases from the initial resistance value and the resonance frequency decreases from the initial frequency, the fingertip M1 is in the hover touch state located near the insulating material 3.

  When the fingertip M1 contacts the insulating material 3, a current flow indicated by a one-dot chain line in FIG. 1 is also generated, and the resonance resistance value is changed from the increased state to the decreased state. That is, as the fingertip M1 is strongly pressed against the insulating material 3 (as the contact area of the fingertip M1 with the insulating material 3 is increased), the skin resistance Rf decreases, so that the resonance resistance value Is changed to a decreasing state. As the resonance resistance value decreases, the resonance frequency decreases. The end point of the hover touch is when the resonance resistance value reaches an extreme value (maximum value) that shifts from increase to decrease. The end point of the hover touch is indicated by a symbol β in FIG. Note that the maximum distance (the distance between the electrode D and the fingertip M1) that can be detected as being in the hover touch state can be 6 cm or more.

  As described above, when the resonance resistance value is larger than the initial resistance value (range α to β in FIG. 2), the increase or decrease of the resonance frequency is opposite to the increase or decrease of the resonance resistance value (that is, When the resonance resistance value increases as the resonance frequency decreases, in other words, the resonance resistance value decreases as the resonance frequency increases), the living body is in a hover touch state with respect to the electrode unit. It can be determined that

  In the final state in which the fingertip M1 is strongly pressed against the electrode part D, the resonance resistance value becomes the minimum value, and the point in time when the resonance resistance value becomes the minimum value is indicated by the symbol γ in FIG. Note that the minimum resonance resistance value when the resonance resistance value is minimized can be determined as the skin resistance value. When the skin resistance value (minimum resonance resistance value) changes in a direction that decreases by a predetermined value or more even though the resonance frequency has hardly changed, it can be determined that the living body M is sweating.

  The posture state of the living body M can be determined based on the resonance resistance value in the range of β to γ (the range in which both the resonance frequency and the resonance resistance value decrease or increase), and from the change in the resonance resistance value A change in posture can be detected. That is, for example, when the living body M is seated in the driver's seat, for example, when leaning on the seat back, when the back is separated from the seat back, or when the hip is lifted from the driver seat, etc. Since the ground position with respect to the vehicle body changes, the resonance resistance value changes. Therefore, by creating a correlation between the posture state of the living body M and the resonance resistance value in advance as a database, it is possible to determine the posture state of the living body M by comparing the acquired resonance resistance value with the database. Become. The posture (change) of the driver sitting in the driver's seat includes, for example, the presence / absence of a foot lift from the floor, the presence / absence of a lift from the backrest (presence of leaning posture), and the like.

  In FIG. 2, the range between β and γ means an increase in the contact area of the fingertip M1 with the insulating material 3, and therefore the insulating material 3 of the fingertip M1 is calculated from the capacitance calculated from the resonance frequency in this range. It becomes possible to acquire the contact area with respect to.

  In the case where the current is a flow indicated by a one-dot chain line in FIG. 1, the circuit resistance Z at the time of resonance is calculated by the following equation (1). In the equation, f is a resonance frequency, and the resonance frequency f can be known by looking at the output state of the high-frequency power source 4. At resonance, L and Cf cancel each other, so that the circuit resistance Z becomes the skin resistance Rf.

  Further, the capacitance value Cf is calculated by the following equation (2).

  Since the resonance frequency f and the inductance L of the induction element 11 are known, the capacitance value Cf can be calculated from the equation (2). The contact area of the fingertip M1 can be obtained from the obtained capacitance value Cf. For example, the contact area can be determined by creating a database of the relationship between the capacitance value Cf and the contact area in advance and comparing the calculated Cf with the database.

  Note that the circuit resistance and the capacitance value can be calculated in the same manner as in the equations (1) and (2) when the current flow is indicated by a solid line in FIG. In this case, when the current is a flow indicated by a solid line, R1 may be used instead of Rf, and Cm may be used instead of Cf. When the current is a flow indicated by a broken line in FIG. 1, Rb may be used instead of Rf, and “Cf + Cp” may be used instead of Cf.

  FIG. 3 shows a case where the steering handle 41 is provided with one electrode portion D. 3 shows a state where the steering handle 41 is in a neutral position. In FIG. 3, the electrode portion D is provided along the entire circumference of the steering handle 41 (over the entire circumference).

  In the example of FIG. 3, the first electrode 1 and the second electrode 2 constituting the electrode portion D have a laminated structure arranged in the vertical direction. That is, in the case of the parallel arrangement, it is necessary to make the second electrode 2 thin, and there is a concern about an increase in resistance. In addition, the smaller the value obtained by dividing the area of the first electrode 1 by the area of the second electrode 2, the sensor sensitivity is improved (the change in the resonance resistance value accompanying the change in the resonance frequency is large). The area of the second electrode 2 is preferably larger than that of the first electrode 1. In the embodiment, the first electrode 1 is positioned below the second electrode 2 (the second electrode 2 is the steering handle). 41 is located on the surface side of 41).

  In the embodiment of FIG. 3, it is possible to determine the posture state of the driver as the living body M by using the steering handle 41 for an automobile that is automatically driven, for example.

  FIG. 6 shows an example in which two electrodes 1 and 2 are stacked and arranged, and the same reference numerals are given to the constituent elements corresponding to those in FIG. In FIG. 6, the second electrode 2 is disposed below the first electrode 1 with a gap. The insulating material 3 is composed of a first insulating material 3A that covers the upper surface side of the first electrode 1 and a second insulating material 3B that insulates between the two electrodes 1 and 2. The two insulating materials A3A and 3B are composed of the same member. In the equivalent circuit shown in FIG. 6, skin resistance Rf does not exist. However, the characteristics shown in FIG. 2 can be obtained also in the equivalent circuit of FIG.

  In FIG. 6, the capacitance Cf is shown between the first electrode 1 and the fingertip M1, but actually, it also occurs between the second electrode 2 and the fingertip M1. At this time, the capacitance between the first electrode 1 and the fingertip M1 is Cf1, the capacitance between the second electrode 2 and the fingertip M1 is Cf2, and the relationship between the two capacitances Cf1 and Cf2 is It defines with following Formula (3). In the formula, RR is a constant.

Cf2 = RR · Cf1 (3)
When the constant RR is changed within a range of, for example, 0.1 to 10 (for example, by changing the width of each electrode 1 and 2), the interval between α and β in FIG. Therefore, the increase in the resonance resistance value accompanying the decrease in the resonance frequency is increased, which is preferable for stably detecting the hover touch (improving robustness). Conversely, the greater the RR, the smaller the interval between α and β, and the smaller the increase in the resonance resistance value associated with the decrease in the resonance frequency. In order to obtain the characteristics shown in FIG. 2, it is preferable to set RR within a range of about 0.1 to 1.0 (this means that the two electrodes 1 and 2 are arranged as shown in FIG. The same is true for a parallel arrangement). In the case of a laminated structure, the relationship between the widths of the two electrodes 1 and 2 is that the second electrode 2 is wider than the first electrode 1 and the larger the RR is, the more the second electrode 2 is the first electrode 1. The length exposed from the width end to the left and right is increased.

  FIG. 4 shows an example of a control system in the present invention. In the figure, U is a controller (control unit) configured using a microcomputer. The controller U receives the current detected by the ammeter 5. Further, the controller U controls the high frequency power supply 4 and the display 42. For example, the display 42 is configured to give a caution alarm or the like when the driver as the living body M has been keeping an unfavorable posture for a long time during execution of automatic driving.

  Next, a control example by the controller U, in particular, posture detection will be described with reference to the flowchart of FIG. In the following description, Q indicates a step. First, in Q1, the high frequency power supply 4 is controlled to change (sweep) the frequency within a specific frequency band range.

  After Q1, an initial resistance value (= R1) and a resonance frequency f1 at that time are determined at Q2. Thereafter, in Q3, a correlation between the resonance resistance value and the resonance frequency is acquired (characteristics as shown in FIG. 2 are acquired, but characteristics in the entire frequency range from the α point to the γ point are obtained. Not necessarily).

  After Q3, it is determined in Q4 whether or not there is a range in which both the resonance frequency and the resonance resistance value decrease or increase. When the determination in Q4 is YES, in Q5, the posture of the driver as the living body M is determined based on the resonance resistance value in the above-mentioned range (checking the resonance resistance value with a database). Thereafter, in Q6, the current resonance resistance value is stored in the database with time (storage in time series format). If NO in Q4, the process ends as it is.

  FIG. 7 shows a control example for determining the presence or absence of a change in the posture of the driver as the living body M and the presence or absence of a decrease in concentration. Hereinafter, FIG. 7 will be described. First, in Q21, the database acquired in Q6 of FIG. 5 is accessed. Thereafter, at Q22, the maximum value of the resonance resistance value within a predetermined time is calculated.

  After Q22, at Q23, it is determined whether or not the current resonance resistance value is equal to or greater than the maximum value calculated at Q22. If the determination in Q23 is YES, it is determined in Q24 that there is no posture change.

  If NO in Q23, it is determined in Q25 whether or not the frequency with which the resonance resistance value changes by a predetermined value or more within a predetermined time is a predetermined frequency or more. When the determination in Q25 is YES, it means that the posture is frequently changed, and it is determined in Q26 that the degree of concentration has decreased. If NO in Q25, the process ends as it is.

  Here, the determination of the posture change can be performed using a database. That is, a database is created in which the driver's posture is changed in various ways, and the amount of change in the resonance resistance value when changing from one posture to another is associated and stored. Then, the change in the resonance resistance value can be checked against a database to determine the posture change. In addition, when the leaning posture is continuously detected for a predetermined time or more, it can be determined that the driver is in a tension state.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. In addition to the detection of the posture (or its change), any one or more detections of detection of the hover touch state, detection of the contact area, and detection of the presence or absence of perspiration can be performed together. The part to be detected is not limited to the fingertip, and may be an appropriate part of the living body such as a foot tip or an elbow. The moving object to which the present invention is applied is not limited to vehicles (particularly automobiles), but can be various objects operated by humans, such as ships and airplanes.

  The present invention is not limited to detecting the posture of a person who operates a moving object, but can be applied in various fields, such as detecting the posture state (or posture change) of a care receiver receiving care. Each step or step group shown in the flowchart indicates the function of the controller U, and the name indicating the function can be attached to the name of the means so as to be grasped as a constituent requirement of the controller U. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention can detect the posture of a living body with an inexpensive configuration.

U: Controller M: Living body M1: Fingertip D: Electrode unit 1: First electrode 2: Second electrode 3: Insulating material 4: High frequency power supply 5: Ammeter R1: Leakage resistance Cm: Mutual capacitance Cf: Capacitance (fingertip) Between)
Rf: Skin resistance Cp: Human body capacitance Rb: Human body resistance 41: Steering handle α: Indicates initial resistance value β: Indicates maximum value γ: Indicates minimum resonance resistance value (shows skin resistance)

Claims (9)

The electrode part is configured by covering the surfaces of the first electrode and the second electrode with an insulating material,
A high frequency power source is connected to the first electrode part via an inductive element for constituting a resonance circuit, while a current measuring means is connected to the second electrode,
A correlation acquisition unit that obtains a correlation between a resonance frequency and a resonance resistance value when a current state indicating resonance is detected by the current measurement unit by sweeping a frequency from the high-frequency power source;
Posture determination means for determining the posture of the living body based on the resonance resistance value in a range where both the resonance frequency and the resonance resistance value decrease or increase based on the correlation acquired by the correlation acquisition means;
A posture detection apparatus for a living body, comprising: In claim 1,
The posture determination unit is configured to determine a contact state between a body of the living body and a ground part. In claim 1,
The posture detection unit is configured to determine a change in posture of the living body based on a change amount of the resonance resistance value within a predetermined time. In any one of Claims 1 thru | or 3,
The living body posture detecting device, wherein the first electrode and the second electrode are arranged along a whole circumference of a steering wheel of an automobile in a stacked relationship.   The living body posture detecting device, wherein the first electrode and the second electrode are arranged along a whole circumference of a steering wheel of an automobile in a parallel relationship. In any one of Claims 1 thru | or 5,
The electrode part is provided on a steering wheel of an automobile,
Based on the posture determined by the posture determination means, further comprising a driver state determination means for determining the driver state;
A biological posture detection apparatus characterized by the above. In claim 1,
It has a database that stores the relationship between the posture of the living body and the resonance resistance value,
The posture determination means determines the posture of the living body by comparing the resonance resistance value with the database;
A biological posture detection apparatus characterized by the above. In claim 1,
A database storing the relationship between the change in posture of the living body and the amount of change in the resonance resistance value within a predetermined time,
The posture determination means determines a change in posture of the living body by comparing the amount of change with the database;
A biological posture detection apparatus characterized by the above. In claim 8,
A living body posture detecting apparatus comprising concentration degree estimating means for estimating a living body concentration degree based on a frequency of a change in posture of the living body determined by the posture determining means.

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