JP2684222B2 - Step detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a step detecting device for specifying the position of a step existing on an object.

[Prior Art] This type of step detecting device is used for automation of various operations such as welding and painting, and detects the step position based on the distance to an object. For example, a light beam such as a laser beam is radiated from above the object, and the reflected light is imaged on the semiconductor position detector (PSD). It is known that the position is continuously detected along with and the point at which the distance changes by a predetermined value or more is specified as the step position.

As such a step detecting device, the applicant of the present application first adds if the difference in distance between adjacent positions on the scanning line has the same sign, and determines that the point having the maximum absolute value of the added value is the step point. By doing so, it has been proposed to eliminate the influence of noise and detect the step position with high accuracy (Japanese Patent Application No. 63-7354).
1). In this device, as shown in FIG. 8 (A), at the step of the object OB, the detected distance continuously changes, so that the difference in distance between adjacent positions is the same. Therefore, the step is detected by focusing on the fact that the maximum value can be obtained at the step by adding this.

[Problems to be Solved by the Invention] Such a step detecting device is an excellent one that accurately specifies the step position with a simple configuration, but the step in the detection target OB is as shown in FIG. 8 (B). , When hitting a point where a plurality of sheet metals are vertically joined, it is difficult to measure the distance because there is a vertical wall portion where reflected light cannot be obtained optically, and as a result, it may be impossible to detect the step. There was a problem.

An object of the step detecting device of the present invention is to solve the above problems and to reliably detect a step even in an object in which a plurality of sheet metals are vertically joined.

Configuration of the Invention The configuration of the present invention that achieves the above object will be described below.

[Means for Solving the Problem] With respect to an object OB in which a plurality of plate materials are overlapped at a step portion, the step detecting device of the present invention that specifies the position where the end of the plate material exists as the position where the step ST exists As illustrated in FIG. 1, a step area specifying unit M1 that specifies an area R where a step ST exists in the object OB, and a surface of the object OB on a scanning line that crosses the specified step existence area R. A light amount detecting means M2 for detecting the light amount of the reflected light from SF, and a step position specifying means for obtaining a position where the detected reflected light amount is maximum and specifying the position as the existing position of the step ST
It is equipped with M3.

[Operation] In the step detecting device of the present invention having the above-described configuration, first, the step area specifying means M1 specifies the area R where the step ST exists in the object OB. The existence area R of the step ST can be specified as an area in which the points at which the distance changes discontinuously exist by measuring the distance to the object OB at a plurality of points on the object OB, for example. It can be specified by various configurations such as specification based on OB design information (for example, CAD information). Of course, a configuration may be adopted in which all the directions of the target object are sequentially regarded as the existence region R of the step and the step is detected.

With respect to the step existing region R thus identified, the light amount detection means M2 is on the scanning line which crosses the step existing region R,
The amount of light reflected from the surface of the object OB is detected. In this case, a light spot may be projected / scanned on the object OB to detect the reflected light amount corresponding to the light spot, or slit light may be projected to detect the reflected light amount at each point. Good. Alternatively, various configurations can be adopted, such as one in which light is projected onto the entire object OB and the amount of reflected light is detected by an optical system along a predetermined scanning line.

Based on the amount of reflected light detected in this way, the step position specifying means M3 finds a position where the amount of reflected light is maximum, and specifies this position as the existing position of the step ST. That is, when a plurality of plate materials are overlapped at the step portion, the step ST position is specified based on the point where the amount of reflected light becomes maximum at this point.

When the light amount detecting means M2 uses projection / scanning of a light spot, the distance to the object OB can be detected based on the image forming position of the light spot, and therefore the step area specifying means M1 It is easy to use it as a part of.

Further, the configuration of the step detecting device of the present invention may be used alone, but it is also preferable to use it together with various conventional step detecting configurations and employ the one having the highest detection accuracy according to the state of the step. is there.

[Embodiment] In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the step detecting device of the present invention will be described below. FIG. 2 is a schematic configuration diagram of a step detecting device as an embodiment of the present invention.

As shown in the figure, this step detecting device projects a light beam onto an object 1 which is going to detect a step, and a light projecting device 3 which detects a scanning position x (i) of the light beam and is reflected by the object 1. A light spot detection device 7 which collects the formed light beam to form a light spot S on the light detector and outputs signals of the position and the light amount of the light spot, and a step existing on the object 1 based on these signals. And a step identification device 10 for identifying First, the configuration and function of each device will be described.

The light projecting device 3 includes a semiconductor laser oscillator 11, a projecting optical system 13 including a convex lens, a scanning mirror 15 that reflects the projected laser light, and a scanning motor that rotates the scanning mirror 15. 16 and a beam splitter 17 for extracting a part of the light reflected by the scanning mirror 15 as reference light
And an X-direction photodetector 19 for detecting the position of the light partially reflected by the beam splitter 17. This laser oscillator 11
The scanning motor 16 and the scanning motor 16 are connected to the step identifying device 10, and each receive a control signal from the step identifying device 10 to oscillate a laser beam and rotate the scanning mirror 15. The rotation of the scanning mirror 15 causes the laser light to be repeatedly scanned in a predetermined direction. This direction is called the X-axis direction. The detection signal of the X-direction photodetector (PSD) 19 in which a part of the scanning light is incident via the beam splitter 17 is input to the step identification device 10, and the distance of the scanning light in the scanning direction, that is, X direction.
It is used to detect the axial position x (i). Position x (i)
The method of detecting (1) will be described later.

On the other hand, the light reflected by the scanning mirror 15 and then transmitted through the beam splitter 17 is projected onto the object 1 as a light beam for step detection. Therefore, when the laser oscillator 11 oscillates the laser beam and the scanning mirror 15 starts to rotate based on the control signal from the step identification device 10, the surface of the object 1 is scanned along the scanning line in the X-axis direction. Beam LB will be projected.

This laser beam LB scanning over the object 1 is the object 1
Scatter and reflect on the surface of. Therefore, the reflected light RB also enters the light spot detection device 7 arranged at a position inclined from the vertically upper side of the surface of the object 1. The incident light is imaged on the Z direction photodetector (PSD) 25 by the optical system 21. The output signal of the Z-direction photodetector 25 is input to the step identification device 10.

In the X-direction photodetector 19 and the Z-direction photodetector 25, one surface of the high-resistance semiconductor surface was used as a uniform resistance layer and electrodes were provided at both ends thereof.
The position of the light spot S on the PSD, that is, the target, is the PSD, and the light generation current lo generated in the semiconductor by the incidence of the light spot S can be extracted from both electrodes according to the resistance value from the light spot S to the electrodes. The scanning position of the light spot on the object 1 and the distance to the object 1 are detected.

FIG. 3 is an explanatory diagram showing the principle of detecting the distance from the position of the light spot S to the object 1. When the position of the object 1 changes vertically to A, B, C and the distance between the light projecting device 3 and the object 1 changes, it is formed on the light receiving surface of the Z direction photodetector 25 of the light spot detection device 7. The position of the formed light spot S moves a, b, and c on the paper surface. That is, the difference in the position of the object 1 corresponds to the displacement Δr on the Z-direction photodetector 25.
The light generation currents l3 and l4 extracted from both electrodes differ depending on the position of the light spot S. Therefore, this photogenerated current l3, l4
By measuring, it is possible to detect the vertical distance to the object 1.

Next, the configuration of the step identification device 10 will be described with reference to FIG. As shown in the figure, the step identifying device 10 includes a driving unit 30 that drives the laser oscillator 11 and the scanning motor 16.
And an X-direction calculation unit 40x for detecting the X-direction position x (i) of the light spot S by inputting the light generation currents l1 and l2 from the X-direction photodetector 19, and a configuration almost the same as this calculation unit 40x. And a Z-direction computing unit 40z for detecting the Z-direction position z (i) of the light spot S based on the light generation currents l3, l4 from the Z-direction photodetector 25, and the X-direction position and Z of the light spot S. Arithmetic and logic operation unit that inputs direction signal and identifies step
It is composed of 80 and.

The drive unit 30 includes an oscillation circuit 31 that generates a clock pulse for setting the light emission timing, a modulation circuit 32 that generates a modulation signal according to the clock pulse from the oscillation circuit 31, and a modulation circuit.
A laser drive circuit 35 that drives a semiconductor laser that is a light emitting element for projecting light of the laser oscillator 11 according to a modulation signal from 32,
A drive circuit 37 for driving the scanning motor 16 is provided. The oscillation circuit 31 and the drive circuit 37 are connected to an arithmetic logic operation unit 80, and the timing of laser oscillation and the rotation of the scanning motor 16 are finally controlled by the arithmetic logic operation circuit 80.

Next, the configurations of the X-direction computing unit 40x and the Z-direction computing unit 40z will be described. However, since both have the same configuration except that there is one A / D converter, the X-direction computing unit 40x will be described as an example. . Since each part of the Z direction calculation unit 40z is the same as the component of the X direction calculation unit 40x, the same numbers are used except for the subscript z.

The X-direction calculation unit 40x is configured to detect the photo-generated currents l1, l2 extracted from the photo-detector 19 connected to both electrodes of the X-direction photo-detector 19.
High-pass filter (HPF) 44 that extracts high-frequency components modulated from the outputs of the two current-voltage converters (l / V converters) 41x and 42x that convert voltage to voltage signals and the l / V conversion circuits 41x and 42x
x, 45x and the output levels of the high pass filters 44x, 45x are checked based on the output of the oscillator circuit 31 (the level is determined in synchronization with the clock pulse). From the detection circuits 47x, 48x and the outputs of the detection circuits 47x, 48x Corresponds to low-pass filters (LPF) 50x, 51x for extracting low-frequency components and photo-generated currents l1, l2 obtained at each electrode of each output signal of the low-pass filters 50x, 51x (this output is the photodetector 19). So the following signals l1, l2
55x) and an adder circuit 56x that adds the output signals l1 and l2 of the low-pass filters 50x and 51x.
x and the first signal (l1-l2) output from the subtraction circuit 55x
And a division circuit 58x that calculates the ratio of the second signal (l1 + l2) output from the addition circuit 56x, and an A / D that converts the output of the analog signal obtained from the division circuit 58x into a digital signal
It is composed of a conversion circuit 60x. Here, the total light generation current generated in the PSD of the photodetector 19 by the light spot S is lo
Then, the relationship between the displacement r of the light spot S and the photo-generated currents l1 and l2 obtained at each electrode is expressed by the following equations (1) and (2) if the resistance layer of the PSD is uniform.

l1 ＋ l2 ＝ lo …… (1) l1－l2 ＝ lo (1-2r / L) …… (2) In addition, L is the total length of PSD. Therefore, the output of the addition circuit 56x corresponds to the total light generation current lo, that is, the light amount of the light incident on the photodetector 19, and the output of the subtraction circuit 55x is
It corresponds to the above equation (2). As a result,
The output of the division circuit 58x is (l1-l2) / (l1 + l2) = 12r / L (3). That is, the signal corresponds only to the position of the light spot S. As a result, the A / D conversion circuit 60x outputs a signal corresponding to the position of the light spot S, which is a digital signal. Since the position of the light spot S on the photodetector 19 corresponds to the position of the laser beam LB on the object 1, that is, the position in the scanning direction (X direction), this is referred to as the X direction position signal x (i). (Symbol i indicates the sampling timing of the A / D conversion circuit 60x).

Further, the Z-direction calculation unit 40z for the photo-generated currents l3 and l4 output from the photodetector 25 in the Z-axis direction has the same configuration as the calculation unit 40x in the X-axis direction.
The signal (l3, l4) / (l3 + l4), that is, the signal z (i) corresponding to the position in the Z direction, is obtained from the / D conversion circuit 60z. The output of the adder circuit 56z is obtained by the above-mentioned equation (1).
Since it corresponds to the total light generation current lo, that is, the light quantity of the light spot S as shown in, the A / D conversion circuit 70 is provided to convert it into a digital signal and output it as the light quantity signal S (i). ing.

The arithmetic logic operation unit 80 for inputting the position signal x (i) in the X direction, the position signal z (i) in the Z direction and the light amount signal S (i) obtained in this way is input port 75 for inputting these signals. In addition to the well-known CPU81, ROM82,
A RAM 84, a serial communication port (SIO) 86, and an output port 88 for outputting a control signal are provided, and these are connected to each other by a bus 89. Therefore, the arithmetic logic unit
By executing the program stored in the ROM 82, the 80 scans the object 1 with the laser beam LB in the X-axis direction, and outputs the X- and Z-direction calculation units 40x, z in the X- and Z-directions. Position signals x (i), z (i) and light intensity signal S (i)
Based on the above, the step existing on the object 1 is detected.

Next, a step position detection routine executed by the arithmetic logic operation unit 80 will be described. When the object 1 is positioned at a predetermined position for detecting a step, the arithmetic logic operation unit 80 activates the processing shown in the flowchart of FIG. 5, and first of all, the position is moved over the entire range scanned by the laser beam LB. Signal x
Processing for detecting (i), z (i) and the light quantity signal S (i) is performed (step 100). That is, the laser beam 11 is driven by driving the laser oscillator 11 and the scanning motor 16 via the driving unit 30.
Position signal x (i), z (i) of the light spot S formed on the photodetector 19, 25 while starting the operation in the X direction.
The light amount signal S (i) is read through the input port 75 at a predetermined sampling timing.

Next, it is determined whether or not there is a step in the scanning range of the laser beam LB (step 110). It can be determined from whether or not there is a step in the scanning range, whether or not the position signal z (i) in the Z direction has a discontinuity, or the design information of the object 1. If it is determined that there is no step, the process ends at "END" and the present routine ends.

When it is determined in step 110 that there is a step in the scanning range, the Z-direction signal z in the entire scanned area is detected.
A process of calculating the sampling number n corresponding to the position P1 where (i) becomes the minimum is performed (step 120). That is, as shown in FIG. 6, the sampling number n corresponding to the position P1 where the object 1 is closest to the light spot detection device 7 is obtained. After that, as seen from the sampling number n, the direction in which the step exists is determined to be the anti-scanning direction when the scanning direction is the scanning direction (step 130). If it is the direction, the value -1 is set to the variable j (step 145). The variable j is for determining in which direction the process is to be advanced from the point where the position signal z (i) in the Z direction becomes the minimum.

After setting the value to the variable j, the position signal z (i) in the Z direction
The sampling number n at the position P1 where the
(Step 150), the Z-direction position signal z (n) at the sampling number n and the Z-direction position signal z at the sampling number k + j separated by j from here.
A process for obtaining a deviation Δz from (k + j) is performed (step 160). Since the value of the variable j is determined based on the direction in which the step exists, the distance to the object 1 at the position corresponding to the sampling number k + j as the position approaches the step becomes It will be larger than the distance. Therefore, in the next step 170, it is judged whether or not this deviation Δz is larger than the predetermined value a, and the sixth
As shown in the figure, a point P2 that becomes larger than the predetermined value a is detected. Until this point P2 is detected (steps 160 and 170),
The value of the variable k is updated sequentially (step 180), and this variable k
It is determined whether or not the value of has become the value kD indicating the edge of the area (step 190). Here, the value kD indicating the edge of the region is
Maximum value of sampling number when looking in the scanning direction
i max, and a value of 0 when looking in the anti-scanning direction. Even if these processes are repeated until the end, if the point where the deviation Δz is equal to or larger than the predetermined value a is not found, it is determined that the step cannot be identified (step 200), the process ends once in “END” and this routine is ended.

On the other hand, this process is repeated (steps 160 to 19).
When it is determined that the deviation Δz has become equal to or greater than the predetermined value a by 0) (step 170), it is next determined whether or not the light amount signal S (k) is the maximum point (step 210). The position P3 where the light intensity signal S (k) has a maximum value can be detected by referring to the values of the light intensity signal S (k) at several adjacent points. If it is determined that the value is not the maximum, the value of the variable k is updated using the variable j (step 220), and it is determined whether or not the value of the variable k becomes kD indicating the end of the area (step 23).
0). The value kD indicating the edge of the region is the same as the value determined in step 190, and even if this determination is repeated while updating the value of the variable k, if the light amount signal S (k) is not determined to be the maximum value, Similarly, if no step is identified (step
200), once disconnect to "END" and end this routine.

Like the object 1 illustrated in FIG.
When the plate materials are stacked, the position signal (distance output) z (i) has a discontinuous value, as shown in FIG. Therefore, it is difficult to identify the level difference by the normal level difference detection method. On the other hand, in this embodiment, the light amount signal S
If a point at which (k) has a maximum is found (step 210), the average value of the Z-direction position signals z (i) at 2c + 1 points in the vicinity of the next maximum point k. z is calculated (step 240), and the position x (i) in the X direction is specified as the step position P4 (step 250). That is, the amount of reflected light S (i) from the object 1 locally takes a maximum value at the end of the plate material existing in the step, and by specifying this position, the step position can be specified.
The reason why the process of taking the average value (step 240) is performed is to improve the accuracy, and the place where the light amount signal S (i) becomes maximum depends on the state of the end.

As described above, according to the step detecting device of the present embodiment, the vicinity of the area where the step exists (position P2 in FIG. 6) is determined by the distance from the object 1 (Z direction position signal z (i)). The light amount signal S (i) of the reflected light from the object 1 detected thereafter
With reference to, the point at which this is the maximum is specified as a step. Therefore, the step is steep and a plurality of plate materials are overlapped at the step, and the distance to the object 1 at the step becomes intermittently unmeasurable (section L1, L2 in FIG. 6),
Even if the measured distance is discontinuous, the step position can be detected with high accuracy. Moreover, in this embodiment, since the light amount is detected by using the photodetector 25 for detecting the position in the Z direction, there is an advantage that the configuration is simplified.

Note that when a plate material or the like is overlapped on the stepped portion, the light amount signal S (i) of the reflected light from the plate material or the like always has a maximum point due to the presence of the end portion T. Even if the plate members are in complete contact with each other as shown in FIG. 7A, even if there is a gap between the plate members as shown in FIG. 7B, the step can be detected reliably.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.
The direction photodetector 25 is of a two-dimensional type, and is also provided with a dedicated sensor for detecting the amount of light by utilizing the structure that also serves as the X direction photodetector 19 and the fact that the light beam is diffusely reflected by the object. Needless to say, the present invention can be implemented in various modes without departing from the scope of the present invention, such as the above configuration.

EFFECTS OF THE INVENTION As described in detail above, according to the step detecting device of the present invention, even when a plurality of plate materials or the like are overlapped at a stepped portion, the step can be surely detected. It has an excellent effect. Therefore, in automating various operations such as welding and painting, it is possible to reliably position the object and improve the work efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram of a step detecting device as one embodiment of the present invention, and FIG. 3 is a principle of distance detection using a photodetector 25. 4 is a block diagram showing the internal structure of the step identification device 10, FIG. 5 is a flowchart showing the processing executed by the arithmetic logic operation unit 80 of the step identification device 10, and FIG. A graph showing the state of each signal obtained, FIG. 7 (A),
(B) is an explanatory view showing the relationship between the state of the step and the amount of reflected light,
FIGS. 8A and 8B are explanatory views illustrating the conventional step detection technique and its problems. M1 ...... step difference area specifying means M2 ...... light amount detecting means M3 ...... step difference position specifying means 1 ...... detection target object 3 ... light projecting device 7 ...... light spot detecting device 10 ...... step difference specifying device, 11 ...... Laser oscillator 15 ... Scanning mirror, 16 ... Scanning motor 19 ... X-direction photodetector, 25 ... Z-direction photodetector 30 ... Drive unit, 40x ... X-direction calculation unit 40z ... Z-direction Arithmetic unit, 80 ... Arithmetic logic operation unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sosei Ikari 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Toshimitsu Isoi 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd. (56) Reference JP 59-99203 (JP, A) JP 61-160005 (JP, A) JP 63-256804 (JP, A) JP 64-74405 (JP, A) JP-A 1-245103 (JP, A)

Claims (1)

(57) [Claims] 1. A step detecting device for an object in which a plurality of plate materials are overlapped at a step portion, which specifies a position where an end portion of the plate material exists as a step existence position. A step area specifying unit that specifies an existing area, a light amount detection unit that detects the light quantity of the reflected light from the surface of the object on the scanning line that crosses the specified step existence area, and the detected reflected light quantity is A step detecting device including a step position specifying unit that obtains a maximum position and specifies the position as a step existing position.