JPH0414723B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a visual sensor that identifies the shape of a workpiece and measures its dimensions during assembly, transportation work, and the like.

[Conventional technology]

Recently, equipment with advanced functions such as robots and automatic assembly machines have been introduced for production automation, but due to lack of information on the shape and position of the target workpiece, it is difficult to respond to changes and assembly There are still many areas, such as manufacturing processes, that still have to rely on human labor. Therefore, visual sensors will be essential in order to further automate these processes in the future. The visual sensor measures, for example, characteristic data such as the area, circumference length, hole area, maximum length from the center of gravity, and minimum length of multiple works that exist separately on the monitor screen, and uses that data for teaching. (Taught) Automatically identifies which work corresponds to the work, or from the window part of the screen,
It has become necessary to have a function to identify specified shapes such as ellipses and rectangles, and efforts have been made to put them into practical use.

[Problem that the invention seeks to solve]

In addition to the above-mentioned recognition functions, the visual sensor also needs to identify the groove as a figure on the target workpiece, and as no effective method has been found for this purpose, there have been problems such as restrictions on the automation of assembly.

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide a visual sensor that can easily and reliably identify grooves in the figure of a target work.

[Means for solving problems]

The visual sensor according to the present invention determines an area where run lengths are continuously connected based on run length data generated by an image processing circuit,
Line element registration means for registering each line element forming the outer periphery of the area, assuming that the line element closest to the point of interest of the groove is the bottom of the groove, and surrounding line elements including that line element a teaching means that recognizes a groove when it forms a predetermined angle and registers characteristic data for specifying the groove; and a teaching means that registers characteristic data for specifying the groove, and when receiving a measurement command from a host computer, the target work registered in the line element registration means. measuring means that determines whether or not the combination of each line element matches the feature data registered in the teaching means, and when a matching combination is found, outputs the feature data of the groove related to that combination to the host computer thereof; It is installed in the central processing unit.

[Effect]

The visual sensor of this invention is equipped with a central processing unit having a line element registration means, a teaching means, and a measuring means, so that closed figures such as circles, ellipses, and rectangles can be detected, and thereby the shape of the groove can be recognized. be done.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1, 1 is a visual sensor control device, 2 is a host controller that gives measurement commands to the visual sensor control device 1, 3 is a target workpiece to be measured, and 4 is a camera that takes an image of the target workpiece 3. Read and convert to video signal. 5 is a monitor TV that displays the original image, binarized image, recognition results, and guidance for various operations. A light pen 6 is used as a man-machine interface during the teaching mode for registering the internal settings of the hardware and the target work to be recognized.
7 is a line element registration means for determining a region in which run lengths are continuously connected based on the run length data generated by the image processing circuit 10, and registering each line element forming the outer periphery of the region; Assuming that the line element L _i closest to the point of interest P of the groove is the bottom of the groove, the surrounding line elements L _i-1 , L _i+1 , including that line element L _i
When L _i-2 and L _i+2 form a predetermined angle (90°), it is recognized as a groove, and the characteristic data that identifies the groove (groove width w, groove depth (left d1, right d2), a teaching mode (teaching means) for registering the groove position (x _c , y _c ) and direction θ), and the object registered in the line element registration means when receiving a measurement command from the host computer 2. It is determined whether the combination of each line element of the workpiece 3 matches the feature data registered in the teaching mode, and if a matching combination is found, the feature data of the groove related to that combination is sent to the host computer 2. A central processing unit 8 having an online mode (measuring means) for outputting is a storage circuit that stores programs to be executed by the central processing unit 7, teaching data, etc., and a storage circuit 9 converts the video signal input from the camera 4 into a binarized image. 10 is an image processing circuit that generates run length data based on the signal output from the image input circuit 9; 11 is an image processing circuit that generates run length data based on the signal output from the image input circuit 9; an image storage circuit that stores binarized images and recognition results;
12 is a monitor interface circuit with the monitor television 5; 13 is a light pen interface circuit with the light pen 6; and 14 is a host interface circuit with the host controller 2.

Next, the operation of this invention will be explained. first,
The operation modes of the visual sensor control device 1 include a teaching mode in which the internal settings of the visual sensor control device 1 and the target work to be recognized are registered, and a teaching mode in which measurements are performed according to commands from the host controller 2 and measurement results are reported to the host controller 2. There is an online mode, which can be selected by instructing with the light pen 6 from the screen of the monitor television 5.

In the teaching mode, the camera 4 reads an image of the target workpiece 3 at regular intervals, converts it into a video signal, and transmits the video signal to the image input circuit 9. The image input circuit 9 binarizes the video signal using the binarization level set as shown in FIG. 2a, and removes isolated points such as noise.
The binarized data is transmitted to Here, P indicates the groove's focus point, WL is the set window range, and D
indicates a binary image of the target workpiece. Then, the original image, the binarized image, etc. are displayed on the monitor television 5 according to the image selection. The operator checks the work No. 2 of the target work 3 while looking at the screen of the monitor TV 5.
The digitization level, type of local feature such as circle, ellipse, rectangle, etc., and window settings are made using the light pen 6 from the screen of the monitor television 5. Further, the point of interest is indicated by a binary image displayed on the screen of the monitor television 5. In the case of grooves, see Figure 2a.
After indicating the inside of the groove with the point of interest P as the bottom surface, the central processing unit 7 gives a command to the image input circuit 9 by instructing with the light pen 6 to start measurement. The image input circuit 9 binarizes the video signal of the target workpiece 3 read by the camera 4 at a set binarization level, removes isolated points, and sends it to the image processing circuit 10 to generate run length data. The central processing unit 7 determines a region where run lengths are continuously connected from the run length data, and creates a line element table by tracking the outer periphery of the determined region (FIG. 2b). for example,
The left side of the area is determined as follows. The left end point of the run length of the first or cutting point in the corresponding area (corresponds to the starting point as a run length)
Let the position of
y(n)], the straight line passing through those two points is expressed by equation (1).

x=x(n)-x(0)/y(n)-y(0)×[y-y(n
)]+x(n)...(1) Here, the x position corresponding to y(1) to y(n-1) is
End points of run length when x _c (1) to x _c (n-1) [x(1), y(1)] to [x(n-1), y(n-1)]
The length in _the x direction with Repeat in the same way.

｜X _c (i) − [x(0), y(0)] to [x(n-1), y
(n-1)] are registered in the line element table as the starting and ending points of one line element along with the slope (FIG. 3). As shown in FIG. 4, the line element table is composed of data on the starting point position, ending point position, and slope for one line element.

Next, the line element closest to the designated groove point 4 on the screen of the monitor television 5 is found using the line element table. In FIG. 2b, line element L _i corresponds to this. The line elements forming the groove are determined using the line element _Li as a reference. In Figure 2b, line elements L _i-1 and L _i+1 correspond to the side surfaces of the groove, line elements L _i correspond to the bottom of the groove, and line elements L _i-2 and L _i+2 correspond to the surface of the groove. It is recognized as a time slot that satisfies the following conditions (rectangular approximation in Figure 2c). In the flowchart of Figure 6, (1) Considering the bottom of the groove of line element L _i , the angle θ i _-1,i+1 formed by line elements L _i-1 and L _i+ 1 is 180°−β° θ _i-1,i+1 180°+β°……(4).

(2) The angles formed by the line elements L _i , L _i-1 and L _i+1 are θ _i-1,i , θ _i,i+
1
When 90°−α°θ _i-1,i and θ _i,i+1 90°+α° 90°−α°θ _i-1,i and θ _i,i+1 90°+α° or 270° −α°θ _i-1,i and θ _i,i+1 ≦270°＋α°…
(5) Be.

(3) The angles formed by line elements L _i-2 and L _i , L _i+2 and L _i are θ _i-2,i ,
When θ _i,i+2, -γ°θ _i-2,i and θ _i,i+2 γ° ...(6).

(4) When the angles formed by line elements L _i-2 and L _i-1 and L _i+2 and L _i+1 are θ _i-2,i-1 and θ _i+1,i+2, 90° −α°θ _i-2,i-1 and θ _i+1,i+2 90°+α° 90°−α°θ _i-2,i-1 and θ _i+1,i+2 90°+α° 270°−α°θ _i-2,i-1 and θ _i+1,i+2 270°＋α°…
(7) Be.

Here, α, β, and γ are permissible values.

If the specified figure is recognized as a groove based on the above judgment result, the teaching data that defines the groove is the groove width w, depth (left and right) d ₁ ,
Find d ₂ using equation (8).

w=l _i d ₁ (left) = l _i-1 × | sin (θ _i-1 − θ _i ) | d ₂ (right) = l _i+1 × | sin (θ _i+1 − θ _i ) | ...(8) Then, the binarization level and window range are registered in correspondence with the work number.

Regarding the direction of the groove, when the slopes from the reference line of the line elements constituting the side and bottom of the groove are θ _i-1 , θ _i , θ _i+1 , the direction of the groove can be expressed by equation (9). demand.

= (θ _i-1 +180°) + (θ _i -90°) + θ _i+1 /3…(9
) As above, the direction θ of the groove is defined and indicated by a straight line passing through the midpoint (x _c , y _c ) of the line element _Li that forms the bottom.

In the online mode, when the visual sensor control device 1 receives a measurement command (with a work number specified) from the host controller 2 via the host interface circuit 14, the central processing unit 7 calculates the window range from the teaching data. ,2
After setting the digitization level, giving a command to the image input circuit 9, reading the image of the target workpiece 3 from the camera 4, and generating a run length in the image processing circuit 10, create a line element table in the same manner as in the teaching mode. create.

Monitor TV 5 in online mode
Since the point of interest is not specified on the screen, the groove is identified in the following steps based on the teaching data from the first line element. In the flowchart of FIG. 7, (1) When the line length of the line element of interest is l _j , find a line element L _j that satisfies |l _j −w/w|δ (10).

(2) Considering line element L _j as the bottom of the groove, the angle θ j-1 _,j+1 formed by line elements L _j-1 and L _j +1 is 180°−β°θ _j-1,j+1 180°+β°...(11).

(3) The angles formed by line elements L _j and L _j-1 , L _j+1 are θ _j-1,j , θ _j,j+
1
When 90°−α°θ _j-1,j and θ _j,j+1
90°＋α° 90°−α°θ _j-1,j and θ _j,j+1
90°+α° or 270°−α°θ _j-1,j and θ _j,j+1 270°+α°…
(12) Must be.

(4) The angles formed by line elements L _j-2 and L _j , L _j+2 and L _j are θ _j-2,j ,
When θ _j,j+2 , −γ°θ _j-2,j and θ _j,j+2 γ° …(13).

(5) When the angles formed by line elements L _j-2 and L _j-1 and L _j+2 and L _j+1 are θ _j-2,j-1 and θ _j+1,j+2, 90° −α°θ _j-2,j-1 and θ _j+1,j
+2 90°＋α° 90°−α°θ _j-2,j-1 and θ _j+1,j
+2 90°+α° or 270°−α°θ _j-2,j-1 and θ _j+1,j+2 270°+α
°…(14).

(6) When the angles of line elements L _j-1 and L _j , L _j+1 from the reference line are θ _j-1 , θ _j , θ _{j+1 ,} depths d ₁ ′ (left), d ₂ ′ (right) is d ₁ ′ (left) = l _j-1 × | sin (θ _j-1 − θ _j ) | d ₂ ′ (right) = l _j+1 × | sin (θ _{j+1 −} θ _j ) | …(15). These depths d ₁ ′ (left) and d ₂ ′ (right) are be satisfied.

Here, α, β, γ, and δ are permissible values.

If there are line elements L _j-1 , L _j , L _j+1 that satisfy the above (1) to (6), calculate the direction of the groove using the same method as during teaching, and send it to the upper controller 2. The measured data d ₁ ', d ₂ ', w, position (x _c , y _c ), and direction θ are reported (Fig. 5 a, b).

〔Effect of the invention〕

As described above, according to the present invention, since a central processing unit having a line element registration means, a teaching means, and a measuring means is provided, closed figures such as circles, ellipses, and rectangles are detected and the shape of the groove is determined. To be recognized,
There is an effect that grooves in a figure can be easily and reliably recognized.

[Brief explanation of drawings]

Fig. 1 is a block configuration diagram of a visual sensor control device according to an embodiment of the present invention, Fig. 2 is a model diagram of an a2 value image, b line element, and c rectangular approximation of a target work, and Fig. 3 is an area of the target work. Figure 4 is a line element table diagram, Figure 5 is a diagram of measurement commands and measurement results from the upper controller, and Figure 6 is a diagram of the measurement results.
The figure is a flowchart of the recognition algorithm during teaching, and FIG. 7 is a flowchart of the recognition algorithm during online. 1 is a visual sensor control device, 2 is a host controller, 3 is a target workpiece, 4 is a camera, 5 is a television monitor, 6 is a light pen, 7 is a central processing unit, 8
1 is a memory circuit, 9 is an image input circuit, 10 is an image processing circuit, 11 is an image storage circuit, 12 is a monitor interface circuit, 13 is a light pen interface circuit, and 14 is an upper interface circuit.

Claims (1)

[Claims] 1. An image input circuit that converts a video signal output from a camera that reads an image of a target work into a binary image, and an image processing circuit that generates run length data from the binary image converted by the image input circuit. , a line element registration means for determining a region in which run lengths are continuously connected based on the run length data generated by the image processing circuit, and registering each line element forming the outer periphery of the region; The line element closest to the point of interest is assumed to be the bottom of the groove, and when surrounding line elements including that line element form a predetermined angle with each other, it is recognized as a groove, and feature data identifying the groove is generated. Teaching method to register,
and when a measurement command is received from the host computer, it is determined whether the combination of each line element of the target workpiece registered in the line element registration means matches the feature data registered in the teaching means, and if they match. A visual sensor comprising a central processing unit having a measuring means for outputting characteristic data of grooves related to a combination to a host computer when a combination is found.