JPS63306894A - Safety monitor method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a monitoring method for ensuring the safety of operations in, for example, various automatic machines.

[Conventional technology]

Conventionally, safety monitoring means in this type of equipment have been configured to detect whether or not a person or object has entered the spatial area where the automatic machine operates, by detecting that the light projected by the phototube has been interrupted.
, a limit switch-like detector with OFF control, the movement of dangerous objects was monitored under the same conditions within the monitoring area.

[Problem that the invention seeks to solve]

Therefore, for example, even if a part of a worker's hand intrudes into the opposite side of the equipment, which is a part of the monitoring area but where no automatic machine is installed, the monitoring device will be activated and the automatic machine will be brought to an emergency stop.

Or, when detecting a person or a moving object, the time it takes for an automatic machine to stop is different depending on whether the person is moving at normal speed, when the person is moving quickly, or even when the person is about to fall. Conventional monitoring under the same conditions results in unnecessary stopping of automatic machines, such as having to assume the worst and stop the operation in the shortest possible time even though there is a difference in time margin. There was a drawback that the operating rate of the machine decreased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible safety monitoring method that can eliminate the irrationality of the safety monitoring means as described above and improve the operating rate of automatic machines.

[Means for solving problems]

The present invention divides the monitoring area into several areas according to the degree of danger, sets criteria for each area such as the size and number of objects to be detected, and the time from object detection to output of a detection signal. This is a safety monitoring method that determines object information, checks the moving speed of the detected object when detected, and changes the time from detection of the detected object to output of a detection signal according to this speed.

(Function) The area monitored by the camera is divided according to the degree of danger, and a detected object detection signal is output depending on the information on the detected object and the moving speed of the detected object, so that the safety level differs depending on the area. The ability to interpret standards provides flexibility in safety monitoring methods.

【Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described based on an embodiment in which the present invention is applied to a safety monitoring device having a visual function shown in the drawings.

FIG. 1 is a perspective view showing an automobile parts welding equipment in this embodiment.

When the operator sets the welding part 9 on the jig table 8 and presses a welding start pushbutton switch that automatically controls the welding robot 7 at a location away from the welding robot 7, the welding robot 7 starts welding work.

At this time, the operator does not know the status of the welding robot 7.
If you approach it incorrectly, it may cause an accident.

Therefore, as shown, the monitoring area 6 surrounding the equipment
A camera 1.2.3°4 is installed above it.
The photographed image is analyzed by the image processing device 5, and it is constantly monitored whether a worker or the like has entered the monitoring area.

In this example, the monitoring area is divided into four areas, cameras 1.2.3.4 are installed in each area, and the cameras are switched in order to perform image analysis, thereby repeatedly checking the entire area. There is.

Additionally, the floor surface, which serves as the background for camera images, is painted in a blackish color.

FIG. 2 shows the brightness characteristics (histogram) of the object to be detected.

Workers' hands 9 gloves 9 work clothes compared to the floor surface.

The detected brightness level of helmets, etc. is displayed. Note that the number of pixels on the vertical axis is a value obtained by dividing the image into small sections, binarizing the colors of the sections into white and black at a certain brightness level, and counting the white pixels.

As can be seen from FIG. 2, the brightness of the hands 9, gloves 9, work clothes, etc. is higher than the background. Therefore, by binarizing the image at a brightness level slightly higher than the brightness level of the floor surface and counting the number of pixels at a brightness level above this binarization level,
The object to be detected is being detected.

FIG. 3 is an explanatory diagram of a speed adjustment means for determining the degree of danger and sending a no-operation signal (emergency stop) to equipment such as automatic machinery.

This example is described with camera 1 in Figure 1 as the target, but
The same applies to others.

FIG. 3(a) is a diagram in which the monitoring area 1 within the field of view of the camera 1 is divided into an equipment side 33 and an anti-equipment side 34 by a window.

The equipment side 33 is an area where there is a risk of direct interference with the welding robot, and the opposite equipment side 34 is an area where there is a risk of spatter.

Safety monitoring device! The number of pixels, which is the area of the object to be detected, within the fSl window 31 and the second window 32 is monitored. As shown in FIG. 3(a), the number of pixels (area) as the criterion for determining inoperability is set larger on the non-equipment side 34 than on the equipment side 33.

For example, the first window 31 has the binarization level L1 and the reference pixel number a1, the second window 32 has the binarization level L2 and the reference pixel number a2, and al>al.

Then, when a person approaches the equipment, a part of the person is first captured in the image from the side 34 away from the equipment. At this point, no operation disabling signal is output. Next, when a person approaches the equipment a little more, the number of pixels (area) within the second window 32 increases, so an operation disabling signal is output. Furthermore, if a person approaches the equipment and enters the first window 31, an inoperable signal will be output even if the detection area is small. This is shown in FIG. 3(b).

Furthermore, as shown in FIG. 3(c), since there is a time period between when a person enters the second window 32 and when the person enters the first window 31, continuous detection of the object within the second window 32 is possible. The reference pixel number in this case is smaller than that in the case of FIG. 3(b). After a continuous time period t1 has elapsed, an operation disabling signal is output. However, if a person enters the first window 31, an operation disabling signal is immediately output.

Furthermore, as shown in FIG. 3(d), focusing on the coordinates of the top position of the detection image 36, that is, the pixel on the equipment side 33, and comparing it with the position in the previous image 35, it is found that [difference 47>L (constant)] ], the moving speed in the y direction is calculated, or the difference image with the previous image 35, that is, the size of the number of pixels by exclusive OR operation between pixels, is a constant value V. If it is larger, a disable signal is immediately output, and if it is smaller, it will be determined during the next image analysis.

In this way, the operation disable (emergency stop) signal is output by the logical sum of the three checks shown in FIG. 3(b), (c), and (d).

By monitoring danger within the operating range of automatic machines as described above, this safety monitoring means is given flexibility in its operation, and it is not possible to monitor based on the same conditions as the conventional monitoring area 6, such as whether or not a person has entered the monitoring area 6. Compared to
The operating rate of welding robots (automatic machines) will improve.

〔Effect of the invention〕

Thus, according to the present invention, the monitoring area for intrusion of a person or object to be detected in the operating range of an automatic machine is divided, and each area is monitored using a different standard, or the moving speed of the detected object is monitored. Thereby, this type of safety monitoring method is much more flexible than conventional means, increasing the efficiency of automatic machines, reducing operating costs and improving reliability of operating safety.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of equipment showing a safety monitoring method according to an embodiment of the present invention, Fig. 2 is a brightness characteristic diagram (histogram) of a detected object, and Fig. 3 is an explanatory diagram of judgment criteria in a monitoring area. . 1, 2. 3.4... Camera, 5... Image processing device, 6... Monitoring area, 7... Automatic machine (welding robot), 8... Jig stand, 9... Welding parts, 31 ...
Window, 32...Second window, 33...Equipment side, 34...Anti-equipment side, 35...Previous image, 36
... Image this time. Applicant's agent Mr. Sato - Figure 1 Figure 2 (α9

Claims (1)

[Claims] 1. The image captured by the camera is binarized at a constant brightness level, and the area monitored by this camera is divided into several areas depending on the degree of danger, and the size and number of objects to be detected are determined for each area. , set criteria for the time from object detection to detection signal output, determine information about the detected object based on these criteria, check the moving speed of the detected object when it is detected, and detect the detected object according to this speed. A safety monitoring method characterized by varying the time from object detection to detection signal output. 2. The safety monitoring method according to claim 1, wherein the information on the detected object is one or more of the following: the form of the detected object, the degree of urgency of protecting the detected object, and the detected position of the detected object.