JP2953858B2 - Motion sickness detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting motion sickness of a moving passenger.

[0002]

2. Description of the Related Art Conventionally, when a passenger feels motion sick, it has been necessary for the passenger to directly notify the crew or to operate a button for calling the crew.

[0003]

In the above-mentioned conventional method, there is a problem that the crew cannot notice the passenger until he / she feels ill and cannot provide appropriate services. .

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to automatically detect a change in mood of a passenger, notify a crew of the change, and provide a more appropriate service to the passenger.

[0005]

In order to solve the above-mentioned problems, a motion sickness detection apparatus according to the present invention is provided by a piezoelectric element embedded in a seat and a voltage change of an electric signal from the piezoelectric element connected to the piezoelectric element. A heartbeat detection device for detecting a passenger's heartbeat, an estimation device for estimating the degree of motion sickness of the passenger from the heartbeat information output from the heartbeat detection device, and an output device for notifying a crew of an estimation result output from the estimation device. It is provided.

[0006]

In the above construction, the piezoelectric element embedded in the seat detects a pressure change at the contact surface between the passenger and the seat caused by the passenger's heartbeat, and converts the pressure into an electric signal. The heart rate detection device calculates the passenger's heart rate from the voltage fluctuation of the electric signal from the piezoelectric element. The estimation device estimates the degree of motion sickness of the passenger from the change in the heart rate output from the heartbeat detection device as needed.
The output device notifies the crew of the estimation result of the estimation device as a perceptible stimulus.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of the present invention. Piezoelectric element 1
Is connected to the heartbeat detection device 2. The heartbeat detection device 2
It is composed of a filter circuit 3, an amplification circuit 4, a smoothing circuit 5, an A / D conversion circuit 6, and an arithmetic circuit 7, and further includes an estimation device 8.
Connected to The estimating device 8 includes an LED as an output device.
Connected to panel 9.

FIG. 2 is a perspective view showing a state in which the piezoelectric element 1 is embedded in a seat. A band-shaped piezoelectric element made of a thin film such as polyvinylidene fluoride is embedded in a seat back portion. This location is particularly useful for detecting pressure changes at the contact surface due to the passenger's heartbeat.

Next, the operation of the motion sickness detecting apparatus according to the present embodiment will be described. The piezoelectric element 1 converts various pressure changes applied to the embedded portion including the passenger's heartbeat into an electric signal.

The heartbeat detecting device 2 calculates the passenger's heartbeat from the electric signal. First, the filter circuit 3 cuts off signals other than the frequency components corresponding to the heartbeat. In the case of an automobile or the like, a signal having a frequency of at least 8 to 10 Hz should be cut because vibration of an engine is transmitted to a seat. The amplifier circuit 4 amplifies the electric signal that has passed through the filter circuit 3. The smoothing circuit 5 rectifies and integrates the amplified signal. The A / D conversion circuit 6 converts the input analog electric signal into digital information every time a conversion command is received from the arithmetic circuit 7. The arithmetic circuit 7 obtains the autocorrelation coefficient of the electric signal passing through the filter circuit 3 from the value from the A / D conversion circuit 6, calculates its fundamental frequency, and obtains the heart rate per unit time.

FIG. 3 is a flowchart showing an algorithm for calculating a fundamental frequency using an autocorrelation coefficient. Real truth
In the example, discrete data is sampled at a sampling rate of 20 Hz.
Is obtained from the A / D conversion circuit 6, and the obtained
The discrete data is represented as data (j). Where the data
The number is N and j = 0 to N−1. In this embodiment,
Rectification and integration processing are performed on the original waveform in the smoothing circuit 5.
Data (j) has a DC component

[0012]

[Outside 1]

Is included. DC component is data
(J) corresponds to the average value. To find the autocorrelation coefficient
A waveform obtained by removing the DC component from the original waveform must be used.
No. Therefore, first, in step 10 of FIG.
Find the average value of

[0014]Next, in step 11, an autocorrelation coefficient is obtained.
The autocorrelation function C (i) required for is calculated. Where i
= 0 to N-1. Let Δt be the sampling interval
And C (i) is a value at a certain point in time and an arbitrary time i ·
This is a function representing a correlation with a value at a time point separated by Δt.
If data (j) is a signal with a period, the phase shift
The value of C (i) changes according to
Repeats the change of taking the maximum value when the phase is shifted
You. In step 11, as described above, data
The calculation is performed using the signal obtained by removing the DC component from (j).
I have.

Next, at step 12, the autocorrelation coefficient R (i)
Ask for. FIG. 4 is a graph of a calculation example of R (i).
It is. R (i) theoretically has a phase shift of data
It takes a maximum value when it is an integral multiple of the basic period of (j). Figure
As shown in Fig. 4, there are local maxima at a, b, c, d, and e.
And If we find the true fundamental period from these maxima,
That is one cycle of the heartbeat, and the heart rate per unit time is
Can be calculated. Step 13 to step 18
This is the step of finding the maximum point of. These maxima are
There are also those that happen to be the local maximum due to errors,
In step 15, a threshold function f (i) is set and exceeds
Are treated as maximum points in step 16. Threshold
The value function f (i) is set, for example, as shown in FIG. this
Thus, the points a and b are smaller than f (i), so
Instead, the points c, d, and e are the maximum points. Step 16 and
According to 17, the function representing these maximum points is peak
It is replaced by a function (x). That is, the point c,
Let x corresponding to d and e be ic, id and ie, respectively.
And peak (x) is maximal when x is ic, id, ie
Take the values R (ic), R (id), R (ie), where x is
Otherwise, peak (x) is 0.

Next, in step 19, peak (j) is maximized.
The value of the argument j which is a value is set as a temporary basic period T. However,
T may still be an integer multiple of the true fundamental period
Therefore, in steps 20 and 21, a cycle of an integral number of T
There is a second local maximum in the vicinity of
(J) Search for an argument j having a value of> 0
You. In the present embodiment, T = ie in step 19.
As in 4, ie is actually a position twice the true fundamental period T.
(2T), the value of T (= ie) 2
Argument j taking a value such that peak (j)> 0 in the vicinity of 1 /
Is searched for, and in step 21, a new ic is
Is assigned to T. It returns to step 20 again and T (=
peak (j)> 0 near half of ic)
Is searched for an argument j to be taken,
Has no such j, so ic is the true fundamental period T
You. Then, using this T, in step 22 the unit time
Heart rate is calculated of or.

The heart rate thus determined is output to the estimating device 8. The estimating device 8 estimates the degree of motion sickness of the passenger from the temporal change of the heart rate. It is known that the heart rate is generally higher in a state called “motion sickness” than in a normal state. This can be used to estimate the degree of motion sickness.

The LED panel 9 as an output device displays the estimation result of the estimation device 8 to the crew. Normally, the green LED is turned on, and when the passenger has motion sickness and has a high heart rate, the red LED is turned on according to the degree. Of course, monitors with multiple seats are also possible. This is effective when mass transportation is intended, such as by airplane, or when crew members, such as buses, cannot patrol the front seats.

[0019]

As described above, the motion sickness detection device of the present invention can detect a change in the heartbeat of the passenger in the seat, and thus can automatically notify the crew of the degree of motion sickness. There is an effect that a more appropriate service can be received.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a motion sickness detection device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which the piezoelectric element 1 in the device is embedded in a seat.

FIG. 3 is a flowchart of a heartbeat calculation algorithm in the apparatus.

FIG. 4 is a graph of an autocorrelation coefficient obtained by the apparatus.

[Explanation of symbols]

Reference Signs List 1 piezoelectric element 2 heartbeat detection device 8 estimation device 9 LED panel (output device)

Claims (1)

(57) [Claims] 1. A piezoelectric element buried in a seat, a heart rate detecting device connected to the piezoelectric element and detecting a heartbeat of a passenger from a voltage change of an electric signal from the piezoelectric element, and output from the heart rate detecting device. A motion sickness detection device comprising: an estimation device for estimating a degree of motion sickness of a passenger from heart rate information; and an output device for notifying a crew of an estimation result output by the estimation device.