JPH10210449A - Monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitoring device which can easily and quantitatively grasp the movement of a monitoring object on a screen and also can easily detect the abnormality of the monitoring object, together with the reduction of the burden for a supervisor by outputting an abnormality warning with respect to the monitoring object, when the changed variable information on the compressed image data exceeds a prescribed allowable level. SOLUTION: An A/D converter is built into a monitoring camera 2, and digital dynamic image data (a) outputted from the camera 2 are inputted to an image compression part 3. The compressed moving image data a1 outputted from the part 3 are inputted to a changed variable detection part 4. The part 4 extracts only a P image frame, for example, from the received data a1 and calculates the total changed variable by totalizing the changed variables which are included in the P image frame. The calculated total changed variable is sent to a comparison part 5, which compares the received total changed variable with the allowance value that has been previously set to an allowable value memory 6. Then the part 5 outputs an abnormality warning (b) with respect to a monitoring object 1, when the total changed variable exceeds the allowance value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring device for monitoring the operation state of various devices installed in various plants, and more particularly to a monitoring device for capturing a moving image to be monitored by a camera.

[0002]

2. Description of the Related Art In general, when unattended monitoring of the operation status of various devices incorporated in various plants is normal or abnormal, a monitor is present at each output value such as the rotation speed of each device. It was displayed on the monitoring panel in the central control room.

Further, a temperature sensor for directly detecting an abnormality of a device is attached to the corresponding device, and a temperature change is monitored in a central control room, or a monitoring camera is installed at a site where the corresponding device is installed. Was displayed on the monitor screen. The observer visually observed the temperature displayed on the monitor panel and the on-site image on the monitor screen, and found an abnormality in the device. When the temperature exceeds the allowable value, an alarm buzzer may be sounded.

[0004]

However, when an abnormality is monitored by a temperature sensor, it is economically difficult to attach the temperature sensor to all parts of the device to be monitored.
If an abnormality occurs in a place where the temperature sensor is not attached, the abnormality cannot be detected.

[0005] In the method of capturing a moving image to be monitored by a monitoring camera and displaying the captured image on a monitor screen, it is automatically determined whether an image displayed on the monitor screen is a normal image or an abnormal image. It was very difficult to inform the observer of the occurrence of the abnormality. Even if it is possible, very high-level image processing is required, and there is a concern that the processing program becomes complicated and that the manufacturing cost of the entire monitoring apparatus increases significantly.

[0006] Therefore, it is necessary to rely on visual observation of the monitor screen by the observer. As a result, due to oversight of important screens, erroneous judgments, individual differences among observers, and the like, it has been difficult to always ensure monitoring accuracy of a certain level or more in monitoring abnormalities.

[0007] Further, it is necessary for the observer to constantly monitor the monitor screen, and there is a problem that the burden on the observer is greatly increased. The present invention has been made in view of such circumstances, and by using a known image compression technology, it is possible to easily quantitatively grasp the movement of an image on a screen and easily detect an abnormality of a monitoring target. It is an object of the present invention to provide a monitoring device capable of reducing the burden on the monitoring personnel and improving the monitoring accuracy.

It is another object of the present invention to provide a monitoring system capable of easily detecting an abnormality of a monitoring target from moving image data obtained by a camera by providing reference image data of the monitoring target and further improving monitoring accuracy. It is to provide a device.

[0009]

In order to solve the above-mentioned problems, a monitoring apparatus according to the present invention comprises a camera for photographing a moving image to be monitored during operation, and a plurality of continuous image frames obtained by the camera. An image compression unit that converts the moving image data composed of the reference image into compressed image data including a reference frame at fixed time intervals and information on the amount of change from the reference frame, and a compressed image data output from the image compression unit. Means for outputting an abnormality warning to the monitored object when the change amount information exceeds a predetermined allowable value.

In the monitoring device configured as described above, a moving image to be monitored during operation is photographed by a camera. The moving image data to be monitored composed of a plurality of continuous image frames captured by the camera is image-compressed by the image compression unit. Generally, moving image data after moving image compression includes a reference frame and information on the amount of change from the reference frame at regular time intervals.

Therefore, when the amount of change information of the moving image data output from the image compression unit exceeds an allowable value, the image to be monitored changes rapidly, and it can be considered that some abnormality has occurred. As a result, an abnormal warning is output.

According to another aspect of the present invention, there is provided a monitoring apparatus for capturing a moving image of a monitoring target during driving, and a method for sampling the moving image data obtained by the camera at a constant period. A frame buffer for storing image data for one screen, a reference image memory for storing reference image data for one screen during normal operation of a monitoring target, and an allowable value of the amount of change in each pixel of the reference image data for one screen Means for sequentially detecting the amount of change of the image data of each pixel stored in the frame buffer from the reference image data of the same pixel stored in the reference image memory; and each of the sequentially detected changes Means for outputting an abnormality warning for the monitoring target pixel when the amount exceeds the allowable value of the corresponding pixel in the allowable value memory.

In the monitoring apparatus thus configured, moving image data captured by a camera is sampled at a fixed period and written into a frame buffer. The amount of change in the image data of each pixel written in the frame buffer from the reference image data of the same pixel stored in the reference image memory is sequentially detected. If the sequentially detected change amount of each pixel exceeds the permissible value of the pixel, an abnormality warning is output for the pixel.

In other words, local abnormalities of the monitored object in pixel units can be reliably and automatically detected. According to another aspect of the present invention, there is provided a monitoring apparatus according to the above aspect, further comprising: an area setting memory for dividing one screen to be monitored into a plurality of areas and storing the divided screen; An allowable value table for storing an allowable value of the total amount of change in pixels, a means for sequentially calculating, for each area, a total change amount indicating the total amount of change in all pixels included in the area; If the total change amount of each area exceeds the permissible value of the same area stored in the permissible value table, a means for outputting an abnormality warning for the monitored area is added.

In the monitoring apparatus configured as described above, one screen to be monitored is divided into a plurality of areas and stored. Then, for each area, when the total change amount indicating the sum of the change amounts of all the pixels included in the corresponding area exceeds the allowable value of the same area, an abnormality warning is output for the corresponding area.

Therefore, for example, when a certain amount of image position which largely changes in the (+) direction and the (-) direction moves in a group within a specific region, the total change amount in the region is small. Since it can be regarded as substantially constant, an abnormality can be detected without setting the above-mentioned allowable value large.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a schematic configuration of a monitoring apparatus according to a first embodiment of the present invention.

A surveillance camera 2 is arranged above or obliquely above a surveillance target 1 composed of various devices constituting various plants. The monitoring camera 2 captures an image of the monitoring target 1 at a constant period of, for example, 1/30 second and outputs moving image data a composed of a plurality of continuous image frames.
Note that an A / D converter is incorporated in the monitoring camera 2, and the output moving image data is converted into a digital value.

The digital moving image data a output from the surveillance camera 2 is input to the image compression unit 3. The image compression unit 3 converts the input digital moving image data a including a plurality of image frames into MPEG (Moving Picture Experts) data.
And it outputs the moving image data a ₁ compressed performs image compression processing in Group) scheme.

[0020] As is well known, this moving image data a in _1, GOP in which the plurality of image frames to 1 summarized as shown in FIG. 2 (Grop of Picture) are arrayed. Then, it is possible collimating direction and random access to reverse the GOP from an arbitrary time position relative to the moving image data a ₁ as a single unit.

In each GOP, in order to ensure the independence of the GOP, a reference is provided for each fixed number of the plurality of image frames, and the GOP is formed only with information of the reference image frame. An I image frame, a P image frame obtained by estimating an image frame after a predetermined time has elapsed from an I image frame or another P image frame in a time elapse direction, a time elapse direction, and this elapse B image frame obtained by performing bidirectional prediction of the opposite direction.

Therefore, the B image frame and the P image frame include only the data of the amount of change from the I image frame as the reference frame. The moving image data a ₁ subjected to image compression output from the image compression unit 3 is input to the next change amount detection unit 4. The change amount detection unit 4 extracts, for example, only the P image frame from the input moving image data a ₁ , calculates a total change amount obtained by summing the respective change amounts included in the P image frame, and calculates the next change amount. It is sent to the comparison unit 5.

The comparing unit 5 compares the total change amount with an allowable value set in the allowable value memory 6 and outputs an abnormality warning b to the monitoring target 1 when the total change amount exceeds the allowable value.
In the monitoring device configured as described above, a commercially available circuit element already developed as the image compression unit 3 can be used. Then, it calculates the amount of change using the P image frame included in the compressed video data a ₁ is output from the image compression unit 3.

Accordingly, with a simple circuit configuration, for example, when an abnormality occurs in the monitoring target 1, the monitoring target 1 can be obtained from the moving image data a captured by the monitoring camera 2.
That the image has changed beyond the allowable value can be automatically detected.

Therefore, it is not necessary for the observer to constantly look at the monitor screen, and the burden of the monitoring work can be greatly reduced. Further, since the occurrence of an abnormality is not overlooked, the reliability of the entire monitoring apparatus can be improved.

In the first embodiment shown in FIG. 1, the image compression unit 3 performs the image compression processing by the MPEG method.
For example, the image compression processing may be performed by a three-dimensional discrete cosine transform (DCT) of x (horizontal), y (vertical), and t (time). In this case, the change amount of the image may be detected based on the time direction component.

(Second Embodiment) FIG. 3 is a block diagram showing a schematic configuration of a monitoring apparatus according to a second embodiment of the present invention. The same parts as those of the monitoring device of the first embodiment shown in FIG. 1 are denoted by the same reference numerals. Therefore, the detailed description of the overlapping part is omitted.

This monitoring device is constituted by a kind of information processing device such as a computer. A CPU (Central Processing Unit) 8 for executing various control arithmetic processing and a monitoring camera 2 take an image on a system bus 7. frame buffer 9 for storing one screen image data a ₂ of the temporary reference image memory 10, the allowable value memory 11, the area setting memory 12, the change amount table 13, the allowable value table 14, the initial value data file 15, a display unit An input / output unit 16 including a keyboard is connected.

The operations of the units 9 to 15 and the stream control unit 19 are controlled by the CPU 8 via the control bus 17. The monitoring camera 2 captures a moving image of the monitoring target 1 and converts the digital moving image data a into the next stream control unit 19.
Send to The stream control unit 19 samples the input moving image data a at a constant period T ₀ such as one second, for example, and writes the sampled image data a ₂ for one screen to the frame buffer 9.

As shown in FIG. 8, the frame buffer 9 stores image data A ₁ , A ₂ ... In pixel units of N pixels constituting one screen. _{A 3, ..., A i,} ..., A N is written. In other words, the frame buffer 9 is an image data A ₁ to A _N of the latest one screen pixel units written from the stream control unit 19 only the predetermined period T ₀ for memory retention. Then, in the next cycle T ₀ , the image data for one screen is updated to the image data in the next cycle.

As shown in FIG. 4A, in the reference image memory 10, image data of each pixel of the moving image data a photographed by the surveillance camera 2 when the monitoring target 1 is operating normally is averaged for a certain period of time. N pieces of reference image data B ₁ , B ₂ . _{B 3, ..., B i,} ..., B N are stored.

As shown in FIG. 4B, the permissible value memory 11 stores image data A _{1 to} A _N for each pixel of moving image data captured by the surveillance camera 2 during operation of the monitoring target 1.
ΔA _{1 to} ΔA from the reference image data B _{1 to} B _N
A _N , each allowable value C ₁ , C ₂ . C ₃ ,
.., C _i ,..., C _N are stored.

Note that the permissible values C _{1 to} C _N of each pixel set in the permissible value memory 11 are not the same values but are set to different values according to each position of the monitoring target 1. I have.

Next, the area setting memory 12 will be described. For example, FIGS. 5A, 5B, and 5C show each area 18 in a case where one screen including N pixels is divided into, for example, n areas 18 when the monitoring target 1 is captured by the monitoring camera 2. FIG. 3 is a diagram showing a position and a shape on a screen. Each area 18 is stored in the area setting memory 12.
And the relationship between each pixel is stored. Specifically, FIG.
As shown in FIG. 7, the number (index) j of the area 18 to which the self belongs is stored for each pixel position i of 1 to N.

1 to 1 set in the area setting memory 12
The shape of each region 18 of n and the number of divisions n are shown in FIG.
(B) As shown in (c), the optimal pattern is set according to the shape of the monitoring target 1 and the driving situation. For example, the monitoring target 1 is divided according to each component such as a vibration-resistant base portion, a rotating shaft portion at which the position of a pixel at which the vibration is generated moves, and a cover portion at which the vibration is likely to be generated over the entire area. Have been.

For example, the patterns of the respective areas 1 to 3 in FIG. 5B correspond to the monitoring target 1a in FIG. 5D. The rotary moving member 20a in the monitoring target 1a corresponds to an annular 3 (j = 3) region in the region setting memory 12, and the reciprocating moving member 20b in the monitoring target 1a corresponds to the region setting memory 1.
2 corresponds to a rectangular area 2 (j = 2).

As shown in FIG. 7A, in the change amount table 13, each of the regions 18 (j = 1 to n) set in the region setting memory 12 includes The change amount ΔA _i ΔA _i = A _i −B _{i represented} by the following equation from the reference image data B _i of the corresponding pixel unit of the image data A _i of the image unit is applied to all the pixel units included in the corresponding region. the total amount of change X _j obtained by adding Te are stored.

In the initial state, the total change amounts X _{1 to} X _n of the change amount table 13 are 0. As shown in FIG. 7B, in the allowable value table 14, for each of the above-mentioned regions (j = 1 to n), the total change amount X ₁ ,
..., X _j, ..., each tolerance Y ₁ of _{X n, ..., Y j,} ..., Y
_n is set.

Each of the allowable values Y _{1 to} Y _n is set to a different value according to the member (position) in the monitoring target 1 in the area to which the user belongs. For example, a small value is set as the permissible value Y for the area of the basic portion of the monitoring target 1 that is less likely to vibrate, and conversely, for the area corresponding to each member such as the cover portion where vibration is likely to occur throughout. Each allowable value Y is set to a relatively large value.

As shown in FIGS. 5B and 5D, in a region corresponding to the rotary moving member 20a and the reciprocating moving member 20b, a fixed amount of pixels are always in the (+) side and the (-) side. Although only the change amount ΔA including the direction is large, the total change amount X over the entire area is averaged and relatively small, so that the allowable value Y is set to a relatively small value.

In the initial value data file 15 shown in FIG.
For each monitoring target 1, each reference image data B _{1 to} B _N set in the reference image memory 10, each allowable value C _{1 to} C _N set in the allowable value memory 11, and each area (j) set in the area setting memory 12 = 1 to n), and the allowable values Y _{1 to} Y _n set in the allowable value table 14 are stored.

When a monitoring command designating the monitoring target 1 is input from the input / output unit 16, the CPU 8 executes a monitoring process according to a flowchart shown in FIG. When a monitoring command is input in S (step) 1, each reference image data B _{1 to} B _N , each allowable value C _{1 to} C _N , and each area (j = 1
To n) and each of the allowable values Y _{1 to} Y _n are stored in the reference image memory 1.
0, allowable value memory 11, area setting memory 12, and allowable value table 14.

Next, each area (j
= 1 to n total change amount X _{1 of), ..., X j, ...} , clears all the X _n 0 (S2). When the above process is completed, and shooting a moving image of the monitoring target 1 by the monitoring cameras 2 (S3), Tokomu image data a ₂ of the stream control unit 19 one screen into the frame buffer 9 (S4). Then, in S5, an index (pixel position) i indicating the position of the read pixel in the frame buffer 9 is initialized (i =
1).

The corresponding position in the frame buffer 9 (pixel position) reads the image data A _i of the pixel units of i (S6),
Next, the reference image data Bi in pixel units at the same position _i is read from the reference image memory 10 (S7). Then, a variation .DELTA.A _i from the reference image data B _i of the image data A _i in the relevant position i (S8).

ΔA _i = A _i −B _i Next, the permissible value C _i of each pixel at the same position i in the permissible value memory 11 is determined (S9). Then, the absolute value | ΔA _i | of the variation ΔA _i is compared with the allowable value C _i (S10),
When the amount of change | ΔA _i | exceeds the allowable value C _i , a warning is output to the input / output unit 16 to indicate the occurrence of an abnormality specifying the corresponding position (pixel position) i of the monitoring target 1 (S11).

Next, the number (index) j of the area to which the corresponding position (pixel position) i belongs is read from the area setting memory 12 (S12). Furthermore, the relevant regions total variation X _j of j is read (S13) a change amount table 13, adding the amount of change .DELTA.A _i to the total amount of change X _j (S14).

When X _j = X _j + ΔA _i or more, pixel unit image data A _{i at} one pixel position _i
Is completed, the index (pixel position) i of the reading position in the frame buffer 9 is updated (S1).
5) When it is confirmed that the updated pixel position i does not exceed the final position N of one screen (S16), the process returns to S6, and pixel-based image data at the next position (pixel position) i in the frame buffer 9 is obtained. The reading process of A _i is started.

In step S16, when the updated pixel position i exceeds the final position N, the 1
It is determined that the monitoring process on the image data a ₂ of the screen has been completed.

Next, after S17, each area (j = 1 to
To start the verification of the total amount of change X ₁ ~X _n in n). First, in S17, a number (index) j indicating an area is initialized to 1 (j = 1). The change table 13 in S18 reads the total change amount X ₁ region j (S18). Next, the permissible value Y _j of the corresponding area j in which the pertinent total change amount X ₁ is stored in the permissible value table 14 is read, and the total change amount X _j is read.
Exceeds the allowable value _Yj (S19), the input / output unit 16
Then, a warning is issued to the effect that an abnormality has occurred in which the corresponding area j of the monitoring target 1 is specified (S20).

If the total change amount X _j is equal to or _smaller than the allowable value Y _j, no warning is issued for the occurrence of an abnormality. When the determination processing for the j-th area is completed, the number (index) j indicating the area is updated (S21). If the updated number (index) j does not exceed the number n of areas, the process returns to S18, and the next step is performed. It starts reading of the total amount of change X ₁ for the area.

[0051] In S22, the updated number (index) j is exceeds the number of regions n, it is determined that the monitoring process on the image data a ₂ of one screen's ipecac in the frame buffer 9 has been completed. If the stop command is not input from the input / output unit 16 (S23), the process returns to S2, clears the total change amount X _j 0 of each area in the change amount table 13, and then monitors the monitoring target 1 by the monitoring camera 2 in S3. The image data a ₂ for the next one screen is taken into the frame buffer 9 from the stream control unit 19 in S 4.

When a stop command is input from the input / output unit 16 in S23, the monitoring process is terminated. In the monitoring device configured as described above, the moving image data a of the monitoring target 1 captured by the monitoring camera 2 has a constant period T ₀ such as one second.
And written to the frame buffer 9 via the stream control unit 19. This frame buffer 9
The change amount ΔA _i of the image data A _i of each pixel written in the reference image data B _i of the same pixel stored in the reference image memory 10 is sequentially detected.

The amount of change ΔA for each pixel which is sequentially detected
_If the absolute value | ΔA _i | of _i exceeds the permissible value Ci of the corresponding position (pixel position) i stored in the permissible value memory 11, the input / output unit issues an abnormality warning for the corresponding position (pixel position) i in the monitoring target 1. 16 is output.

That is, a local abnormality of the monitoring target 1 in pixel units can be reliably and automatically detected. Further, one screen of the monitoring target 1 is divided into a plurality of areas 18 and stored in the area setting memory 12. Then, each region (j = 1 to n)
For each, the total amount of change X _i indicating the sum of the variation .DELTA.A _i of all the pixels included in the corresponding area exceeds the allowable value Y _j of the same region, the abnormal warning to the corresponding area is outputted from the output unit 16 You.

As described above, the presence or absence of an abnormality in each area is determined based on the average change amount of each pixel belonging to the corresponding area. By setting each allowable value Y _{1 to} Y _n to a different value in an area such as a cover part where the expected area is expected, and in another area such as a base part, the presence / absence of abnormality in the monitoring target 1 can be automatically detected with higher accuracy. Can be monitored.

Further, for example, as shown in FIG. 5 (d), in the area 18 corresponding to the rotating member 20a and the reciprocating member 20b, a fixed amount of pixels are always in the (+) side and the (-) side. Although only the change amount ΔA including the direction is large, the total change amount X over the entire area is averaged and relatively small, so that the allowable value Y can be set to a relatively small value. As a result, an abnormality can be detected without setting the allowable value Y large. That is, even in such a special case, the presence or absence of an abnormality can be monitored with high accuracy.

The present invention is not limited to the above embodiments. In each embodiment, for example, a normal industrial monitoring camera 2 is adopted as a camera for capturing the monitoring target 1, but an infrared camera for capturing a temperature distribution of the monitoring target 1 may be used. In this case, if the temperature of a specific position of the monitoring target 1 suddenly rises, an abnormality warning is issued even if the external appearance of the monitoring target 1 does not fluctuate or vibrate. That is, an internal failure that cannot be determined from the appearance can be reliably detected by detecting the temperature rise.

[0058]

As described above, in the monitoring apparatus according to the present invention, for example, the movement of an image on a screen can be quantitatively easily determined from compressed moving image data output from a known image compression apparatus on the market. I know. Therefore, it is possible to easily detect the abnormality of the monitoring target, reduce the burden on the monitoring personnel,
In addition, monitoring accuracy can be improved.

In the monitoring apparatus according to another aspect of the invention, by providing the reference image data to be monitored, an abnormality in the monitoring target can be easily detected from the moving image data obtained by the camera, and the monitoring accuracy can be further improved. .

Further, one screen to be monitored is divided into a plurality of regions, and the total change amount of the image data is calculated for each region.
The presence / absence of an abnormality is determined for each area by comparing with an allowable value. Therefore, it is possible to more accurately and more appropriately monitor the presence or absence of an abnormality for each position or member to be monitored, thereby further improving the monitoring accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a monitoring device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing image-compressed moving image data output from an image compression unit of the monitoring device.

FIG. 3 is a block diagram showing a schematic configuration of a monitoring device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing storage contents of a reference image memory and an allowable value memory of the monitoring device.

FIG. 5 is a diagram showing an example of setting an area in the monitoring device.

FIG. 6 is a diagram showing storage contents of an area setting memory of the monitoring device.

FIG. 7 is a diagram showing storage contents of a change amount table and an allowable value table of the monitoring device.

FIG. 8 is a diagram showing storage contents of a frame buffer of the monitoring device.

FIG. 9 is a flowchart showing a monitoring operation of the monitoring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Monitoring target 2 ... Surveillance camera 3 ... Image compression part 4 ... Change amount detection part 5 ... Comparison part 8 ... CPU 9 ... Frame buffer 10 ... Reference image memory 11 ... Allowable value memory 12 ... Area setting memory 13 ... Change amount table 14: Allowable value table 16: Input / output unit

Claims (3)

[Claims] 1. A camera that captures a moving image to be monitored during driving, moving image data composed of a plurality of continuous image frames obtained by the camera, and a reference frame at regular time intervals and a reference frame An image compression unit for converting into compressed image data comprising change amount information from the image compression unit; and an abnormality warning for the monitoring target when the change amount information of the compressed image data output from the image compression unit exceeds a predetermined allowable value. A monitoring device comprising: 2. A camera for capturing a moving image to be monitored during operation, and a frame buffer for storing moving image data obtained by the camera at regular intervals and sampling the latest image data of one screen. A reference image memory that stores reference image data of one screen during normal operation of the monitoring target; an allowable value memory that stores an allowable value of a change amount of each pixel of the reference image data of one screen; Means for sequentially detecting a change amount of the image data of each pixel stored in the frame buffer from the reference image data of the same pixel stored in the reference image memory; and each of the sequentially detected change amounts is the allowable value memory. Means for outputting an abnormality warning for the pixel to be monitored if the permissible value of the pixel is exceeded. 3. An area setting memory that divides the one screen to be monitored into a plurality of areas and stores the divided area, and for each of the areas, an allowable value of a total sum of the change amounts of all pixels included in the area. A permissible value table to be stored; means for sequentially calculating, for each of the regions, a total change amount indicating a total of the change amounts of all the pixels included in the corresponding region; and a total change amount of each of the sequentially calculated regions. 3. The monitoring apparatus according to claim 2, further comprising: means for outputting an abnormality warning for the area to be monitored when the value exceeds an allowable value of the same area stored in the allowable value table.