JP2004000660A - Heart rate signal correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heart rate signal correcting method which can properly perform the correction of a heart rate signal using a reference value which is introduced by an appropriate value as a reference value for a heart rate signal examination. <P>SOLUTION: An average value of heart rate signal intervals when heart rate signals of which the variation in the intervals is within a specified % are continuously measured for a specified number of times or more is made the reference value for the heart rate signal examination. By paying attention to the variation of the continuous heart rate intervals, and when the variation does not stay in a specified range, the heart rate signal intervals can be canceled even if they are in a proper range as heart rate intervals for a human being and can be prevented from being reflected upon the reference value. Signals having intervals being not more than the specified % of the reference value from among measured heart rate signals are canceled. Also, for signals having intervals being not less than the specified % of the reference value, signals for an interpolation are inserted between them. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for correcting a heartbeat signal using a reference value of a measured heartbeat signal.
[0002]
[Prior art]
When measuring a heartbeat signal and using the heartbeat information, there are many cases where only inaccurate information can be obtained due to electrical noise, movement of the subject, or the like. For this reason, it is necessary to check whether noise is included in the measured heartbeat signal, but conventionally, it was measured using upper and lower limits that are reasonable as human heartbeat intervals. He is only checking the validity of the heart rate signal.
[0003]
Also, if a continuous heartbeat signal is required, even though the measured heartbeat signal is apparently noisy or missing, for example, a correction to remove noise from the measured heartbeat signal It is necessary to perform correction for compensating for the missing part of the heartbeat signal. As a reference value for the correction at this time, an average value of the heartbeat intervals has been conventionally used.
[0004]
[Problems to be solved by the invention]
However, it is difficult to say that an accurate inspection is performed in a system with a lot of noise only by checking the validity using the upper limit value and the lower limit value. Also, the correction of the heartbeat signal cannot cope with the case where noise is accidentally mixed in at a timing satisfying the condition of the human heartbeat interval. In addition, there is a possibility that inaccurate information may be mixed in the creation of the reference value, and correction based on such a reference value will result in an inaccurate heartbeat signal after correction. Would.
[0005]
The present invention has been made in view of such a point, and a purpose thereof is to appropriately correct a heartbeat signal using a reference value derived as an appropriate value as a reference value for a heartbeat signal test. The present invention provides a heartbeat signal correction method.
[0006]
[Means for Solving the Problems]
Therefore, the present invention is characterized in that the average value of the heartbeat signal intervals when the heartbeat signals whose intervals vary within a predetermined percentage or less are continuously measured a predetermined number of times or more is used as a reference value for a heartbeat signal test. are doing. By paying attention to the variation of the continuous heartbeat interval, if the variation does not fall within a predetermined range, even if the variation is within a range appropriate for the human heartbeat interval, the cancellation is performed so that the variation is not reflected in the reference value.
[0007]
The heartbeat signal correcting method according to the present invention has a first feature in that, of the measured heartbeat signals, signals at intervals of less than or equal to a predetermined% of the reference value are canceled. The second feature is that a signal for complementation is inserted between signals at intervals equal to or greater than a predetermined value of the reference value obtained by the above derivation method.
[0008]
Of course, it is preferable to perform both of the above-described correction methods together. In this case, signals at intervals of less than a predetermined% of the reference value are canceled, and signals at intervals of more than a predetermined% of the reference value are complemented between them. Signal is inserted.
[0009]
At the time of signal insertion, it is preferable to arrange the signals in such a number and position that the respective intervals formed by inserting the signals are closest to the reference value.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail. FIG. 2 shows an example of a system configuration for implementing a reference value derivation method and a heartbeat signal correction method. A physical change due to a heartbeat detected by the pickup 2 from the subject 1 is converted into an electric signal by the detection circuit 3, converted into a digital signal by the binarization circuit 4, and then input to the microcomputer (CPU) 5. . The derivation method and the correction method are implemented by a method suitable for the CPU 5, and specific operations are performed in the CPU 5. Hereinafter, the derivation method and the correction method will be described assuming this system. It is assumed that the above system has a configuration of a system and a control program that recognizes a rising edge of a signal as a heartbeat.
[0011]
First, as to the derivation of the reference value, as shown in FIG. 1, the data detected in step 202 is used as interval data in step 203. Next, at step 204, the validity of the interval data is checked. This is to check whether the human heartbeat interval is normal, and as described in the conventional example, the upper limit value (H-limit msec) and the lower limit value (L-limit msec) of the human heartbeat interval. Check if it fits between. It is considered that these two values slightly change depending on the use of the system, the state of the subject of the system, and the like.
[0012]
If it is determined in step 204 that there is an abnormality, the accumulated number of detections is canceled and the next interval data is waited. If it is normal, it is checked in step 206 whether the variation of the interval is within ± R%. If the same person is in the same state, the range of variation of the heartbeat interval must be much narrower than the normal range inspected in step 204, and a continuous signal having large variation is determined to be noise. can do. The threshold value R here also depends on the subject and the system and cannot be unconditionally determined, but a value of 20 to 30% can be suitably used.
[0013]
When it is determined in step 206 that there is an abnormality, the processing is performed in the same manner as in step 204 described above, and if it is normal, 1 is added to the number of detected data (step 207). By repeating the above process, when X consecutive normal interval data are detected, an average value thereof is obtained and set as a reference value. Regarding X at this time, if it is too small, the reliability of the value will be low, and if it is too large, it will take too much time to obtain the reference value. Therefore, about 3 to 10, preferably about 5 is appropriate.
[0014]
Next, a correction method for correcting the measured heartbeat signal using the reference value will be described. First, as for a false alarm such as a case where noise enters the original heartbeat signal, as shown in FIG. 3, if the measured interval data of the heartbeat signal is smaller than A% of the reference value, it is determined to be abnormal. It is assumed that the rising edge obtained this time is canceled and is not detected. It is also determined that the previous rising edge is normal as the interval data, but there is a possibility of a slight shift back and forth, so cancel and set the rising edge two times before as the last reliable edge and set the next edge. Perform processing.
[0015]
Next, as shown in FIG. 4, when a measured heartbeat signal interval data is greater than B% of the reference value, a false alarm such as a case where the original heartbeat signal is lost is obtained. Assuming that a signal to be detected during the edge has not been detected, the following signal is complemented.
[0016]
FIG. 5 shows a supplementary routine. In step 502, interval data that is considered to include a plurality of undetected signals in between is divided by a reference value. The obtained answer is converted into an integer by an appropriate method such as rounding in steps 503 and 504, and then 1 is subtracted. The value thus obtained is used as the number of signals to be complemented, and the number of complementary edges (heartbeat signals) is arranged in the interval data. In this arrangement, these are arranged at regular intervals.
[0017]
As the values of the threshold values A and B for the above correction, values of A = 80% to 60% and B = 125% to 150% can be suitably used. Since it depends on the system to be implemented, it cannot be decided unconditionally. For example, in a system in which the heartbeat interval is expected to gradually widen (for example, a system that induces sleep), the value of B should be set to be large and the value of A should be set to be small. Is added, more accurate correction can be performed.
[0018]
It is, of course, preferable that the correction for the false report and the unreport is preferably performed in combination, and the flow in this case is shown in FIG. After the correction for the false report, the correction for the unreport is performed. It is possible to cancel interval data that is too short compared to the reference value and treat the data as interval data having an interval that is too wide to perform complementation, and it is possible to expect simplification and speeding up of the algorithm.
[0019]
Although the above system has been described as a real-time processing system as an example of the description, the present invention is not limited to the real-time processing system but can be applied to a batch processing system.
[0020]
【The invention's effect】
As described above, in deriving the reference value for the heartbeat signal inspection, since a variation range is set, a more accurate reference value can be derived in a short time. In the heartbeat signal correction method of the present invention, signals at intervals of less than a predetermined percentage of the reference value are canceled, and signals for intervals of at least a predetermined percentage of the reference value are replaced with signals for interpolation derived from the reference value. In the insertion, more accurate correction can be performed in order to use an accurate reference value. In particular, simplification and speeding-up of the algorithm can be expected by canceling the interval data that is too short compared with the reference value, and performing interpolation by treating the data as interval data having an interval that is too wide instead of correcting it.
[0021]
In addition, at the time of complementation by inserting a signal, by arranging the number and position such that each interval created by inserting the signal is closest to the reference value, it is possible to complement a signal closer to the actual heartbeat signal. it can.
[Brief description of the drawings]
FIG. 1 is a flowchart relating to derivation of a reference value in the present invention.
FIG. 2 is a system configuration diagram of the above system.
FIG. 3 is a flowchart relating to correction for a false report.
FIG. 4 is a flowchart relating to correction for unreported information.
FIG. 5 is a flowchart for complementary correction.
FIG. 6 is a flowchart relating to correction.
[Explanation of symbols]
1 subject 2 pickup 3 detection circuit 4 binarization circuit 5 CPU

Claims (4)

The average value of the heartbeat signal intervals when the heartbeat signals whose variation in the interval is within a predetermined percentage is continuously measured a predetermined number of times or more is set as a reference value for a heartbeat signal test. A signal at an interval equal to or less than a predetermined% of the signal is canceled. The average value of the heartbeat signal intervals when the heartbeat signal whose variation in the interval is within a predetermined percentage is continuously measured a predetermined number of times or more is set as a reference value for a heartbeat signal test. A method for correcting a heartbeat signal, wherein a signal for complementation is inserted between signals at a predetermined interval or more. The average value of the heartbeat signal intervals when the heartbeat signal whose variation in the interval is within a predetermined percentage is continuously measured a predetermined number of times or more is set as a reference value for a heartbeat signal test. A heartbeat signal correction method comprising: canceling a signal having an interval equal to or less than a predetermined%, and inserting a signal for complementation between signals having an interval equal to or more than a predetermined% of the reference value. 4. The heartbeat signal correcting method according to claim 2, wherein the signal is inserted at a number and at a position such that each interval formed by inserting the signal is closest to the reference value.

Images