JPS5993292A - Measuring head for robot - 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 The present invention relates to a measurement head for measuring the relative position between a work object and the robot in a work robot, and particularly when the surface of the work object is a flat or gently curved surface. It can be effectively used, for example, when welding thick plates.

A conventional example of a case where an arc welding robot advances welding by touching a welding line is shown in FIGS. 1 to 3.

In the figure, G, l G, is simply written as G when there is no need to distinguish between the objects to be welded CGt, Gtk), and its surface Jl
, Jt (JI J2 sharpeners that do not need to be distinguished are simply J or (), T is the welding torch, W is the linear part to be welded (
(hereinafter referred to as the weld line).

Figure 1 shows magnetic sensors A attached to both sides of welding torch T.
1・2. This detects the relative position between T and G, .G2, and maintains the welding torch at the correct bath welding position i.

Figure 1 (a) shows a light beam L' projected from a light beam projector onto the surface of the object to be measured, and an image camera I that captures the bright line produced when the light beam L' is swung left and right. It detects W and proceeds with the work. Figure (b) shows the image obtained at this time. In this case, the distance DT between the measurement point and the welding point is set to prevent interference with the welding arc light.
It requires about 1 otyrb or more, which is not preferable in terms of keeping the T in the correct position.

In Figure 3, the welding torch T is swung left and right by a certain angle to proceed with welding, but the torch position is controlled so that the arc currents on the left and right sides are equal, and the welding line W is overflowed. This allows you to proceed with your work. Figure P) is a state diagram when the torch position flit control is not performed, and Figure P) is a state diagram after the control is executed.

In the case of Fig. 1 and Fig. 3 above, during welding work, welding l・-
Control is performed after the machine is in the correct working position, and is not suitable for complete automation. In the case of FIG. 1, the disadvantage is that the distance between 'r and the measurement point becomes large and the accuracy deteriorates.

The present invention makes it possible to measure the surface of an object with a relatively simple configuration, and makes it possible to fully automate welding. This will be explained below.

Figure ≠ shows the overall configuration of a measuring head for a robot according to the present invention. In the figure, M is the measurement head, and the axis ξ fixed to it
, η, (and translated about the spatial axis X+y+Z. Therefore, M can have any pose at any position in space by translation and rotation. Also, As shown in the figure, the emitter and receiver are mounted at a certain distance d on the ξ axis, and on that side, the direction 4M including the 80th plane is called the front direction, and this front direction is ± by the rotation of M around the axis ξ
You can roll it to 9.

The projector is a thin beam f (such as a laser beam).
t). f(t) is always within the ξC plane, and the angle θL with the ξ axis can be changed in several steps. The value of this θL is θ-', L=t, 2. It is expressed as...

When f(tl is projected onto the surface J of the object to be measured, the projected point becomes a bright point, that is, a bright spot, and generally the surface J is also diffusely reflected.

As shown in Fig. 5, the light receiver 1t consists of a lens A and a dot-like light receiving element B, and the center of t coincides with OR, and the direction of the line connecting OR and B, that is, the line of sight of the light receiver 1t, is always It is in the ξζ plane, and its direction is indicated by the angle between the ξ axis and BO□,
Also, the line of sight is on both sides of the central direction θR, that is, 0R
It shall be varied within ±φ. In order to change the line of sight direction, the entire photoreceiver box may be swung by φ φ around 1kOR, but since the entire photoreceptor is heavy, only the light receiving element B, which is light and small, can be placed on both sides of the / axis equally ±φ. You can shake it as much as you like.

The light receiver is arranged to be focused on B by the image yLvc of the bright spot A7 on the object surface. Therefore, the distance ORB is Z and A 5
It should be adjusted according to the distance tRL from the At position, but if this adjustment is insufficient, the AbO image at the position B will be blurred and formed thickly, so the position of At will remain constant,
When the line of sight is moved, the electric output e generated by the light receiving element B changes as shown in Fig. 6 with respect to the fluctuation of φ. Therefore, when e is sliced at a constant level, the central value φ (using Q , it is possible to accurately capture the bright spot position.

θ should be set to a value that ensures that AL can be captured when the line of sight direction of the receiver changes by B + φ ([). You just have to take into account the degree of accuracy.

The light beam f(tl) has a wavelength of low energy in the arc light spectrum, and is modulated with an appropriate wave that is not included in the fluctuations of the arc light.

In this way, interference of arc light can be reduced by distinguishing signals from noise depending on the presence or absence of modulated waves emerging from the light receiver R.

In measuring the surface of an object, the front direction of the measurement head M is swung over a range Lf by reciprocally rotating M around the ξ axis. This direction is expressed as a function Q(t) of time t
It is expressed as If we keep the rate of change of 9(t) slow,
The bright spot A moves slowly on the surface of the object. At this time θb
If =i is set, the moving locus of the bright spot will show the shape of the cross section when the object to be measured is cut by the plane of light. The bright spot moves up and down depending on the unevenness of the surface 1 of the object to be measured.

Next, widen the direction of the line of sight of the receiver sufficiently (take the ORA
The direction of ・ is always included in UH±φ, and the direction angle of the line of sight of the receiver R is set as a function of time to be φ(1), and the direction is much faster than f(t). Make it change periodically.

In this way, for each cycle of φ(1), the line of sight of the receiver will always change at least once (twice when φ(1) is a reciprocating vibration, and twice when φ(1) is a reciprocating vibration,
1) When the change is in one direction, the light passes through the bright line once), and when the line of sight and the bright line intersect, an electrical output is obtained from the light receiving element B of the light receiver. Using this electrical signal as a time signal, φ
(r), 9 (t) can be obtained.

When θL-1, when φ(1) is found, t, = d
tan (IJR + φ (t)), tR45, = d〆 light beam O,
Let A, ;Q, be a perpendicular line drawn to AM, and A, Q, =
1. , oゎQmu.

jL=dsln%t)jan(θ8+φ(t)), p,
=dcxs9G)lJ+Jl(On+φ(tl) −(
2) Generally, for any σL, the shape of the bright line when the measuring head M is rotated around the ξ axis and the bright spot AJ is moved is such that when θ, -1, the object cannot be flattened. The cross-sectional shape is shown when the stopper is 7r/a.
In this case, the curve becomes complicated because it represents the cross-sectional shape when the object is cut by a conical surface.

Therefore, in order to know the shape of the cross section, mainly θ, =
The reason for measuring π/2 and measuring π/Q is used only to obtain the information necessary for control. be done.

Since the period of change of φ(1) is much shorter than that of φ(1), there are AI + A2 +...Anl on the emission line.
Since the lines of intersection of a large number of lines of sight and emission lines are determined, the shape of one cross section of the object is determined.

By performing the above measurements while moving the measurement head M in the ξ-axis direction, for example, the shape of the surface J of the object to be measured is determined.

A case will be described in which a plane is measured using the above-mentioned measurement head. First, when the measuring head is faced to a plane with θ f'-5, the locus generated on the plane J becomes clearly a straight line, as shown by A and AMAl in FIG. θ1
If we change ′〈η, the surface on which the five light beams rest becomes a cone, and this conical surface and the plane J.

The line of intersection with is a quadratic curve, which is an ellipse or a hyperbola. This situation is shown in FIG.

In the case of the ζ-axis 15 plane of the measurement head, the following two conditions hold true.

'LL "" 114, Nitsu=shi...
・・・・・・・・・・・・Tap (7) η-axis It of the measurement head In case of J plane, tL□=trJ2 ・・・
・Song・・・・・・・・・・・・・・・ (8) Measurement head's ξ axis II In case of J plane! , u
=l-M ・・・・・・・・・・・・・・・Four old songs・hit・・song・・・su・・・・(9) Using the above interlude, the surface of an object When the plane is formed of a plane, it is possible to detect the intersection line W between the planes of the surface and to identify whether the plane intersection is V-shaped or Δ-shaped. Next, I will explain the outline.

Now, the measurement head is directly facing the plane J (J on the ζ axis
Suppose that the plane continues to move along the plane J2 and approaches the intersection line W between J and the plane J2, then
Since the condition of equation (7) does not hold (b), the condition of equation (7) does not hold (if the cross IIMWllη axis is shown in Fig. 0), then the condition of mind/MtL = t1. In addition, if the intersection line W is not parallel to the η axis, it will be as shown in the figure ←), and the center-droplet LX, □ki1
．． , and as the measuring head advances further, the second
tL1kitL.

In the case of figure (a), if ↓ to the center, then △ bulge plane intersection (the center increases). If xM<y:;, then the bulge plane intersection (l decreases)
In the case of figure (b), tL〉tI, , then △bulge plane intersection (t
L□ increases)tL□<tL, then v bulge plane intersection (L
If the weld line intersects the V bulge surface (L□ decreases), then at the intersection of the bulge surfaces using the identification method described above, use the following method to locate the measuring head directly facing the weld line W0 (J .

On the bisecting plane of J2, directly facing Wo, and taking the distance from Wo to a predetermined value of X4), do welding work? Start.

The measurement head is further moved to create a light beam with %l = 0 (
This light beam coincides with the axis direction) is W.

Stop moving the measuring head at the position where a bright spot appears.

This position is detected when the value of AMσ in the diagram deviates from a constant value. Here, by changing θL'a to 0'L, rotating the measurement head around the axis, and detecting a point where the deviation deviates from a constant value, AMA'h1 in the figure is made to coincide with WO.

Next, as shown in FIG. 1O, the measurement head is rotated around the ξ axis so as to directly face the surface J. In the figure, the suffix Jtk is added to the bright spot A as a symbol at this time. The rotation angle at this time is clearly equal to the angle formed by the planes J and J. To place ol, on the co-equal surface of angle JIWOJ2, convert OX, to 0LAutan as shown in the figure.
% to the left l\, then 01, and rotate around the ξ axis to bring the measurement head directly facing the bath tangents W and K (oI, A in Figure io).

Against the direction! /2 J, side ＼ rotation, the ξ axis becomes W
o and coincides with O5□AM). Next, OL□01
Transfer it to ゜01. , AM is set to a value of 4, which is suitable for welding work.

Since the measuring head is placed in the welding position by the above procedure, the welding torch is also in the welding position.

The measurement head can be controlled during welding work by performing a simple first check.

(11) tTJ□=LXJ8.4= for θL〈
The conditions (1) and (ii) for the maximum value at /4 are that OI is on the bisector of the angle formed by the plane J1 + J2, and the distance from the bath tangent is a predetermined value of 4. 8, ξ axis If W
This indicates that it has become (・).

Explain how to reduce interference caused by welding arc light (noise light) TK- and the measurement circuit. Welding arc emits strong light, which is used as a light beam (signal light) for measurement.
Since the superimposed light of both enters the incident point of the light receiving element B, the electrical output of the light receiving element B naturally contains a large amount of noise. To facilitate separation of this signal and noise,
A wavelength of the signal light that is not included in the spectrum of the welding arc light is used, and a shielding plate is used to shield the arc light. Alternatively, it is a great idea to remove noise light using an optical filter, but if the light beam f(t) is modulated with a wave that is not included in the noise light, this modulation will be reflected in the output of the photoreceiver. Depending on whether the component is present or absent, it can be determined whether the line of sight of the light receiver has captured a bright spot or not.

An example of the measurement circuit is shown in FIG. In the figure, LIT
, 8. D is an oscillator that generates an electric signal to emit a modulated light beam from the projector; this output is amplified by an amplifier AMP, / and enters the rear projector, producing a light beam f.
(t) is fired. On the other hand, the outputs of LIT, S, and D enter the standard voltage generator circuit 8TAND, VVc, which generates a constant standard voltage, and this voltage enters the ratio measuring device A, TIO. The light beam f(t) is reflected by the surface J of the object to be measured and enters the light receiving element B, which has 6 light receivers, and the output of the light receiving element is amplified by the amplification filter MP, , 2, and is the same as the modulated wave. After passing through the filter BPFt that only passes the component, and circuits F, S, and D that detect the modulation frequency and output it, it enters the ratio measuring device AT IO, and then the standard voltage generating circuit 5TND,
The ratio between the output of
When the value of this ratio is larger than the standard value, circuit D that takes the difference
IP: 7 (Russ signal is output from TS, and this signal is
The analog value of R(t) + Te(t), θ1)(t) is used as a time signal for sampling. When the value of said ratio is less than C, no output is produced from the circuit DIF, TS. Circuit θB (t) +p(tl, 6.
) are the OR (tl) of the 6 light receivers, '/(t) of the measuring head M of the 5 light emitter, θX of the light emitter, (
1) Generate a drive output to give the angular fluctuation as follows, output the values of θ1(t) and 9(tL/J2(t), and perform sampling and A/D conversion on each of them.
Circuit 8AMP.

Enter person/D. In this case, each θ t1. f(tl
, 'b (tl is adjusted so that there is no time delay with the DIF' and T8 circuits.

0R(tl + '7' (t), θ', "(t) is the microcomputer MIO 几, ooM
If input to p, the previously prepared programs LL, +, ZRH, f
Calculations of j, n, etc. are performed, and control signals necessary for controlling the measurement head are generated.

What has been explained above also holds true even if the emitter and six light receivers are replaced. That is, the measurement head M is given angular vibration (i9 gun) and the line of sight direction of the light receiver I7 is set to θ? The direction of the light beam of the projector is set so that (fR<t
Almost the same results as described above can be obtained even if the time periodic function is changed much faster than l (temporal periodic function 0 seconds + φ (1) and the electrical output is obtained from the photoreceiver at the point where the line of sight and the emission line intersect.

In the above description, we used a light receiver (luns and a point-like light receiving element on its optical axis) to focus a bright spot image on the object onto the light receiving element, and +φ(
tl to find the intersection of the line of sight and the bright line.However, instead of waving the line of sight of the receiver, use a light receiving array A in which the full VC light receiving elements are swayed in a linear manner. However, we can make exactly the same expression 1j as 5. The configuration of the light receiver in this case is shown in Figure 1.2. In this case, regarding OI, V1 is exactly the same as the above case, but the angle between the central axis direction of the receiving light 6 and the ξ axis is taken as the OR, and the bright spot on the surface of the target 6 itl constant object is As shown in , there is a note in ALA when moving from the central axis ORA and becoming OR person.
The change in the line of sight direction that is equivalent to one phase is the previously mentioned φi
) is calculated using the following formula.

Here, f: Distance between the light receiving array and the center OR of the lens when the light receiving array is placed at the position where the image of the lens focal length t+7-, :17 is formed.The actual distance between the light receiving array and the center OR of the lens is the image forming position of the light receiving array A. Since it is difficult to always adjust accurately, the image on the A eaves of A is somewhat blurred and large, and electrical output is obtained from multiple light receiving elements. It is sufficient to take the value located at and use it as the distance from the center.In this way, given time t, θ□+φ(t) at the same time.

? (If you read tL OL7, it is possible to perform the same measurements as the previous measurement head for robots.The measurement circuit is slightly different, but it will be omitted because it is simple.

Further, it is assumed that the measurement head and the bath welding torch are connected in a predetermined relationship, and can be easily placed in the welding work position by a control signal from the measurement head.

This is also easy to implement.

Finally, referring to FIG. 5, a method will be described in which the position of the light receiving element B is vibrated in the ξζ plane parallel to the first lens surface to change the light receiving direction angle φ(1) of the light receiver. As shown in FIG. 13, two leaf springs N, N.

If the lower end of the is clamped to the base D, and the support stand U made of magnetic material is attached to the upper end, and an alternating current is passed through the excitation coil of the TFT magnet 0, the support stand U will be as shown in figure (b). Since its upper surface vibrates in parallel to the upper surface of the base D, the light receiving element B mounted on the support U performs the desired vibration. Furthermore, if the structure is as shown in FIG. 144(a), the light-receiving element B can be brought into contact with the support base U! If an alternating current is applied to the excitation coil of magnet 0 to drive it, B will vibrate in parallel to the left and right as shown in figure (b). In the figure, l is a lens, F
is the supporting frame. ηη' is the rotation axis of the entire photoreceiver, and is used for adjusting θ8.

In this way, by vibrating the support U in parallel motion, it is possible to apply vibration to the light receiving element B and vibrate φ(0) at a relatively high frequency.

In the above example, electromagnetic force was used as the excitation force, but it goes without saying that the same driving force can be achieved using other driving forces such as electrostrictive force.

As is clear from the above description, the use of the robot measurement head of the present invention provides the following remarkable effects.

(1) Automatically detects the welding line of the object to be bathed and positions the measuring head, welding torch, etc. in an appropriate position for welding.
It becomes possible to proceed with welding work automatically. Furthermore, even during welding work, the relative position between the welding line and the measurement head can be detected using a simple method, and the work can be continued while making positional corrections, so it is possible to easily cope with welding lines that are somewhat unfocused.

(2) By adding waveform modulation (for example, sine wave modulation, pulse modulation, phase modulation, etc.) that is not included in the welding arc light (noise light) to the light beam (signal light) used for optical cutting, the It becomes easier to separate electrical output signals and noise, improving measurement accuracy.

(3) The device is simple and relatively inexpensive.

[Brief explanation of the drawing]

Figures 1, λ, and 3 are explanatory diagrams of the measurement method of conventional arc welding robots, Figure ≠ is a diagram showing the configuration outline of the measurement head of the robot of the present invention, and Figure 5 is its light receiver. Fig. 6 is a diagram showing the relationship between the shape of the electrical output of the photoreceiver and time in the case where the mapping position of the photoreceiver is incorrectly adjusted, and Fig. 7 is a diagram showing the light beam and bright line when the measurement head measures a flat surface. Figure R is a diagram showing the situation when the measuring head measures the intersection of two planes and identifies the shape of the plane intersection. (2) is the case where the η-axis is not parallel to the intersection line W of the plane. Figures 1 and 2 show a total of 1tllj head ff: directly facing the welding line and at a position suitable for welding work. The process of making K parallel, Figure io shows the measuring head at the optimal welding position directly facing the welding line on the bisecting plane of the intersecting angle of the two planes. A diagram showing the measurement circuit of the head, FIG. 12 is a diagram showing a configuration overview when an array of light receiving elements is used in the light receiving part of the light receiver of the measurement head of the present invention, and FIGS. 13 and 1 are the light receivers. It is a diagram showing an example of a mechanism that gives a small angular vibration in the direction of the line of sight. distance, 1゛: bath welding torch, G1 + (J2: workpiece, Jl+ J2: surface of Gl + G2, W:
Bath tangent, B: lens, B: light receiving element, R: bright spot, LIT
, 8. D=oscillator, 5TAND, V two-type quasi-voltage generation circuit, ATIO: ratio measuring device, AMP/, 2: amplifier,
EPF: Filter, F, S, D: Detection circuit, DIF,
T8: Level value 1 [Which difference circuit, MIO, oo
Mp: microcomputer, U: support stand, D: base,
0: Electromagnet, Nl. N: Support spring, F: Support frame. Patent Applicant Japan Telecommunications Technology Co., Ltd. O/Senj tIr Cron end, 3 bacteria j4hi13ψ (tbl! 1 deficiency is φ(t) Fang Otsu drunkenness” 74th Proceedings Amendment Book Showa Ei July 2013 Otsu "Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office, Statement of the Case Patent Application No. 2002rr 1982, Title of the Invention Measuring head for robot 3, Person making the amendment Contents of the amendment [ ψ(R)
(t) Correct J and Ashi as “ψ(υ)”.)

Claims (1)

[Claims] (υ a certain distance d on the central axis ξ of the robot measuring head
At a point 01.0R separated from , an emitter and a receiver are installed facing each other, and the emitter passes through OL within the ξCC plane of orthogonal axes ξ, η, (with OL as the origin,
A sharp light beam is emitted in the direction that makes an angle θL with the ξ axis, and the angle θ
X, can be changed from 1 to several steps, and the receiver has a lens center at the OR, and a lens for focusing the image of the bright spot formed by the light beam of the projector on the surface of the object to be measured, and a lens for receiving the bright spot image. The line of sight of the light receiver is within the ξζ plane, passes through the OR, and connects the ξ axis and the oR.
It forms an angle of 10φ(1), and in the direction of OR, the line of sight takes a direction near the bright spot, and due to the temporal periodic function φ(1), the line of sight repeats small oscillations, and a certain angle during the angular oscillations. to capture the bright spot so that the light-receiving element generates an electrical output, and then vibrate the entire measuring head around the ξ axis at an angle given by a periodic function of %), so that the above line of sight captures the bright spot. Using the electrical output generated from the light-receiving element as a time signal, find φ(,1) and 9<t), find OR+φ(t), 9<t), and combine this value with d+
A measuring head for a robot, characterized in that the relative position between the measuring head and the object to be measured or the shape of the surface of the object to be measured is determined by using 'j@. (2. In claim 1, instead of the light-receiving element of the light receiver, a large number of light-receiving elements are arranged in a line at the position of the light-receiving element within ξ (plane, substantially orthogonal to the line of sight) For a robot, the robot is equipped with a light-receiving array consisting of a light-receiving array, the position of the element is determined by an electric signal generated from the element at the position of the bright spot image, the direction of the line of sight is determined, and @(1+ is determined by the electric signal). Measurement head. (3) In claim 1, when the line of sight direction of the light receiver is changed periodically according to a time function of θR + φ (1), OR means that the lens of the light receiver and the entire light receiving element are ORed. The φ(tl) is adjusted by rotating around an axis parallel to the η-axis, and the φ(tl) causes only the light-receiving element to vibrate with a small amplitude, thereby changing the viewing direction of the light-receiving device. (4) A measuring head for a robot according to claim 3, characterized in that the light receiving element is supported by two parallel springs so that the light receiving element moves in parallel. Head. (5) In claim 1, the line-of-sight direction angle of the light receiver '4g: / or a value of several steps θRL (1=l・ko,
3...), the direction angle of the projector is θL+ψ([
), σL is set in advance as a value near the intersection of the line of sight of the receiver and the surface of the object to be measured, that is, the viewpoint, and ψ
(By angular vibration with a small amplitude tl, the bright spot is caused to pass over the viewpoint, and the electric output of the light receiving element that is generated when the bright spot and the viewpoint overlap is used as a time signal, %), ψ (1
), and the relative position between the measuring head and the surface of the object to be measured or the surface shape of the object to be measured is obtained using d+liL +ψ(t), θ. (6) Claims 1, λ, and 3. In Sections 1 and 5, the optical beam of the projector is modulated by a sine wave, repetitive pulse, etc. to reduce noise interference with signal detection at the output side of the receiver. Measuring head for robots.