JPS58198779A - Ultrasonic sensor device - Google Patents

Abstract

PURPOSE:To obtain a device useful to a welding robot or the like, by analyzing the variance of the intensity of a reflected wave in a receiving part provided in a sensor head, which is rotated at a constant speed, to calculate and output the distance and the angle between the sensor head and an object face. CONSTITUTION:When relative positions of a sensor head 2 and an object face 7 are shifted in the direction perpendicular to the object face 7, the position of the sensor head 2 is moved in such direction that the intensity of a ultrasonic wave is maximum. When the sensor head 2 and the object face 7 are not perpendicular to each other, the angle of the sensor head 2 to the object face 7 is corrected in the direction, where the difference between the maximum value and the minimum value of the intensity is smaller, to make the sensor head 2 and the object face 7 perpendicular to each other. The distance between them is corrected in the direction, where the distance is maximum, to make relative positions of the sensor head 2 and the object face 7 proper.

Description

[Detailed description of the invention] The present invention relates to an ultrasonic sensor device.

For example, when a welding robot performs welding while moving a torch on a plane, the torch needs to maintain a constant angle with respect to the plane, and conventional welding robots are taught this in advance.

However, it is desirable for future welding robots to have the ability to perform welding while visually detecting the welding line. A sensor that can simultaneously detect the angle and angle will be needed.

The present invention was proposed in view of the above circumstances, and aims to provide an ultrasonic sensor device that simultaneously detects distance and angle to a target surface, and which emits ultrasonic waves toward the target surface. a sensor head comprising an axially symmetrical arrangement of a beam emitting section and a receiving section for receiving ultrasonic waves reflected from the target surface; means for rotating the sensor head at a constant speed around the axis; The present invention is characterized by comprising a position calculation circuit that analyzes fluctuations in the magnitude of reflected waves received by the receiving section and outputs the distance and angle between the sensor head and the target surface, respectively.

An embodiment of the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram showing its circuit configuration, FIG. 2 is a partially enlarged view showing the modified signal generator of FIG. 1, and FIG. FIG. 4 is a partial enlarged view showing the extreme value detector of FIG. 1, and FIG. 4 is a characteristic diagram of the ultrasonic emitter of FIG.

Fig. 5 is a side view showing the case where the sensor head is perpendicular to the target surface and at a predetermined distance, Fig. 6 is a side view showing the case where the distance changes in Fig. FIGS. 8 and 9 are explanatory diagrams showing the case where the sensor head is tilted at a predetermined distance with respect to the target surface, and FIGS. 10 and 11 are diagrams showing the intensity of the reflected waves, respectively. An explanatory diagram showing the case where the head tilts with respect to the target surface and the distance changes. Figure 12 is a diagram showing the intensity of the reflected wave in Figure 5. Figure 13 is a diagram showing the intensity of the reflected wave in Figure 6.
Figure 14 is a diagram showing the intensity of reflected waves in Figures 8 and 9;
The figure is a diagram showing the intensity of reflected waves in FIGS. 10 and 11.

”) First, in Fig. 1, l is the central axis of the sensor head 2, and the sensor head 2 has a structure that allows it to rotate around the central axis 1 at a constant rotation speed.S is the characteristic shown in Fig. 4.・This is an ultrasonic emitting part with a built-in ferrite transducer and emits ultrasonic waves with a constant frequency ω0 toward the target surface 7. 4 is a receiving part of the ultrasonic waves reflected from the target surface 7, which includes a ferrite transducer. The received ultrasonic wave is converted into an electric signal here. 5 is the traveling path of the ultrasonic wave emitted from the emitting part 3, and 6 is the traveling path of the ultrasonic wave emitted from the emitting part 3, reflected by the target surface 7, and sent to the receiving part 4. The path of the incident reflected wave, 18 is a frame that supports the ultrasonic sensor f-z 2 so that it can slide in the axial direction and rotate around an axis perpendicular to the plane of the paper, and 19 is the target surface 7.
The angle made by the central axis 1 of the ultrasonic sensor head 2 is 90
20 is a motor that rotates the sensor head 2 within the plane of the paper in order to correct it to 0; 20.21 is a coil that transmits a signal from the signal generator 26 to the emitting unit 3 using mutual induction; 22
．． 23 is a coil that transmits the signal from the receiving unit 4 to the amplifier 27 of the sensor driving device using mutual induction; 24
25 is a motor that provides a constant rotation speed to the central axis 1 of the sensor head 2, 25 is a motor that slides the sensor head 2 in the axial direction to correct the distance between the sensor head 2 and the target surface 7, and 26 is an ultrasonic wave generator. The frequency ω is passed through the coil: 11, 20 to the emitting part 3 of the coil. a signal generator that transmits a sine wave signal of
21 is an amplifier (AMP) that receives the signal from the receiver 4 via the coils 112.23 and amplifies it; 28 is a signal that comes from the receiver 4 among the output signals of the amplifier 27 and has a frequency ω. 29 is a detector that detects the signal from the filter 28 and extracts the DC component; 31 is a force 1 that corrects the relative position of the sensor head 2 and the target surface 1 based on the signal from the detector 29; as the distance correction signal e
and a correction signal generator that outputs an angle correction signal f, respectively.
32 is a D/A converter that outputs a drive signal for the angle correction motor 19 that corrects the angle between the sensor head 2 and the target surface 7 in accordance with the angle correction signal f from the correction signal generator 31;
3 is a D/A converter that outputs a drive signal for a distance correction motor 25 that similarly corrects the distance between the sensor head 2 and the target surface 2 using a distance correction signal from a correction signal generator 31.

Next, to explain the configuration of the correction signal generator 31, in FIG.
35 is an extreme value detector that measures the maximum value a and minimum value of the detector output that occurs at this sampling time) and adds the maximum value a and the minimum value, C=
The adder %36 which outputs a + b subtracts a and b and outputs d=a-b, and the subtracter 37 outputs e == a
+b is a subtractor that outputs the difference ex e -c' between c'-a'+b' and C at the sampling time just before the measurement.If e-c'==o, then sensor head 2 and This means that the distance to the target surface 7 is appropriate, e - e'> o or e - 'e' (if o, then d' = IL at the sampling time immediately before the measurement.
A subtractor that outputs the difference f = d - d' between l - b' and d. If d - d' = o, it means that the angle between the sensor head 2 and the target surface 7 is appropriate, that is, 90°. It means d - d'> o or d - d'< .

If so, a signal for correcting the angle formed between the sensor head 2 and the target surface 7 is output depending on the magnitude and sign.

Furthermore, to explain the configuration of the extreme value detector 34, as shown in FIG. This is a maximum value register for detecting the maximum value of a signal within a fixed time interval, and the contents of this maximum value register 40 become zero when a reset pulse output from the timing pulse generator 46 at fixed time intervals is input.

41 is a comparator, maximum value register 40 and A/D converter 3
9 and the contents of the maximum value register 40 are A/
When it is smaller than the value of D converter 39, A/D converter 3
When the signal No. 9 is input to the signal selection gate 42, the contents of the maximum value register 40 are similarly converted to the contents of the A/D converter 39. 43 is a comparator, which connects the minimum value register 44 and A/
The output difference of the D converter 19 is detected, and when the difference is negative or zero, the contents of the minimum value register 44 are changed to the contents of the A/D converter 39, and the output of the signal selection gate 45 is sent to the A/D converter. 39
If the output difference is positive, the output of the minimum value register 44 is set as the output of the signal selection gate 45.

44 is a minimum value register, and 45 is a signal selection gate, which selects the output of the converter 39 within the time interval between the reset pulse output from the timing pulse generator 46 and the next reset pulse, as in the case of maximum value detection. Output the minimum value. 46 is a timing pulse generator that outputs a pulse signal that zeros the contents of the maximum value register 40 and minimum value register 44 at regular time intervals, and uses this timing pulse to control the output fluctuation of the A/D converter 39 for a certain period of time. The maximum and minimum values of the output of the A/D converter 39 that appear when measured are measured, and the A/D
The maximum and minimum values of transducer 39 are remeasured. This timing pulse is used by the motor 2 that rotates the sensor head 2.
If the rotation speed of 4 is fo times/second, it occurs at 2fo times/second.

In such other devices, before explaining the specific effects of the embodiments, first, the principle of the device of the present invention will be explained based on FIGS. 5 to 7.

First, when the sensor head 2 is perpendicular to the target surface 1 and at an appropriate distance l, the incident wave and the reflected wave of the ultrasonic wave follow paths 5 and 6 shown in FIG. If the position of is too far away and becomes e + Δg, the reflected wave will follow path 8, and if it is too close and becomes l - Δg, the reflected wave will follow path 9. Therefore, the reception intensity of the reflected wave at receiver 4 will be as shown in Fig. 7. It changes as shown in , and becomes smaller than when the sensor head 2 is at the distance g.

Therefore, the sensor head 2 detects the point P where the intensity of the received wave is maximum and performs position control so that the intensity of the received wave is always P.

Next, the relative position between the sensor head 2 and the target surface 7 is set at the fifth position.
If the state shown in the figure is tilted as shown in FIGS.
0. In FIG. 9, since the light is reflected along the path 11, it is no longer detected by the receiver 4.

Furthermore, if the target surface 7 is tilted and the distance is not appropriate, the ultrasonic waves will travel along the reflection paths 50 and 52 in Figure 1O and the reflection paths 54 and 56 in Figure 11, so that the reception will be received in this case as well. No ultrasound is received in section 4.

Therefore, in the present invention, a device is used in which the spatial intensity distribution characteristics of the ultrasonic waves emitted from the emitting section 3 are shaped like a spheroid as shown in FIG. Here, the distance γ from the origin O to the surface of the spheroid indicates the intensity of the ultrasonic wave in the direction indicated by the angle θ.

In other words, the intensity of the emitted wave is maximum in the direction perpendicular to the surface of the emitting part 3, and the intensity of the emitted wave decreases in the direction not perpendicular to the surface of the emitting part 3 as the angle θ increases. When θ=90°, this intensity becomes zero.

By using the ultrasonic wave emitting unit 3 having such characteristics, even if the relative position between the sensor head 2 and the target surface 7 is not appropriate, the ultrasonic wave emitted from the emitting unit 3 can be The reflected waves are received by the receiver 4 because they travel along the path 12 in FIG. 8, the path 13 in FIG. 9, the paths 61 and 53 in FIG. 10, and the paths ss and sr in FIG. This is what happens.

For convenience of explanation, the case where the sensor head 2 does not rotate has been described above, but in the present invention, the sensor head 2 is configured to rotate around the rotation axis 1.

Then, first, the sensor head 2 and the target surface 1 are connected to the fifth
As shown in the figure, the relationship between the intensity r of the ultrasonic waves emitted from the emitting part 3, reflected by the target surface 7, and received by the receiving part 4 and the rotation angle θ of the sensor head 2 when the sensor head is in the proper relative position. is a circle with radius γ↑, 1, as shown in FIG. 12, and γ·) is constant regardless of θ.

In addition, if the relative position between the sensor head 2 and the target surface 1 is shifted in the direction perpendicular to the target surface 7 as shown in FIG. The relationship between the sensor head 2 and the rotation angle θ is a circle with a radius γ1, as shown by the solid line in FIG. 2 and the target surface 7 are made appropriate.

Next, as shown in FIG. J8 and FIG. 9, if the sensor head 2 and the target surface 7 are not perpendicular, r.

The relationship between θ is a thin line of peanut history as shown by the solid line in Figure 14, and θ = 0° (Figure 8) and θ = 180° (Figure 9).
In Figure), γ is maximum, θ=90° and θ=270
At °, γ is at its minimum.

Therefore, when θ takes the maximum value and the minimum value every 90 degrees, the sensor spatula 1 can be adjusted by correcting the angle of the sensor head 2 with respect to the target surface 7 in a direction that reduces the difference between the maximum value and the minimum value. The relative position between the sensor head 2 and the object surface 7 is made appropriate by making the head 2 and the object surface 7 perpendicular and correcting the distance E in the direction in which r is maximized.

Furthermore, the relative position between the sensor head 2 and the target surface 7 is the first
In the cases shown in Figures 0 and 11, as shown in Figure 15, the figures are similar and smaller than those in Figure 14, so the relative positions are corrected in the same way as in Figure 14. This is what you will do.

Next, the effects of this embodiment based on the principle described above will be described.

First, the constant frequency ω output from the signal generator 26. The sine wave signal is transmitted to the ultrasonic emitting unit 3 via the coils 21 and 20, and the ultrasonic wave is emitted from the emitting unit 3 to the target surface 7, and the ultrasonic wave reflected from the target surface 7 is transmitted to the sensor head 2 and the target. The signals are received by the receiver 4 along the routes shown in FIGS. 5 to 11 depending on the relative position of the surface 7.

At this time, the sensor head 2 rotates at a constant rotation speed f0 around the central axis 1.
Since it rotates at a rate of rotations per second, the intensity γ of the ultrasonic waves received by the receiver 4 changes as shown in FIGS. 12 to 15 according to the rotation angle θ of the sensor head 2. This change in γ occurs because the sensor head 2 rotates at a constant rotation speed f0 times/second, so the maximum and minimum values of γ occur at 210 times/second as shown in Figures 14 and 15. .

This change in γ is converted into an electric signal by the receiver 4 using the ultrasonic wave (frequency ω.) as a carrier wave, which is amplified by the amplifier 27 via the coils 22 and 23, and the output of the amplifier 27 is sent to the filter 28.
When only the component of the ultrasonic wave ω0 is selected by inputting the ultrasonic wave ω0 into the ultrasonic wave ω0, and the output from the filter 28 is detected by the detector 29, an output proportional to the intensity γ of the ultrasonic wave received by the receiver 4 is obtained.

Next, the maximum and minimum values of the output of the wave detector 29 are input to the extreme value detector 34 of the correction signal generator 31 at a period of 1/2 fa seconds, so the circuit shown in FIG. You can find the maximum value a and the minimum value of input.

Information on the relative position between the sensor head 2 and the target surface 7 is similarly stored during the next cycle of 1/2 f o seconds. The maximum value a and the minimum value a are determined by the circuit of the correction signal generator 31 shown in FIG. It is possible to output signals e and f for correcting the position relative to the surface 7.

The correction signal generator 31 has a constant cycle of 1/2/.

Detect the maximum value a and the minimum value within seconds, c = a +
b means that the larger C is, the closer the sensor head 2 and the target surface 7 are to the proper relative position in terms of distance, since a and b are proportional to γ as described earlier in the principle of this device. do.

C in one period and in the following period; (e ′=, /
+b') and outputs the distance correction signal e of the sensor head 2 in the direction of increasing C. On the other hand, the difference between the maximum value a and the minimum value d = a - b is expressed as a and b are proportional to r. Therefore, if the sensor head 2 is at a proper angle with respect to the target surface 1, that is, 90 degrees, a = b and d = O.

Also, when d = a - b ζ 0, it means that the central axis 1 of the sensor head 2 is not perpendicular to the target surface 7, and the larger d is, the closer the central axis 1 of the sensor head 2 is to the target surface 7.
This means that the angle formed by the sensor head 2 and the target surface 7 is far from an appropriate angle.

The distance correction signal 6 is set to a certain value of e0=co when starting the ultrasonic sensor drive device, and the angle correction signal f0 is set to a certain value e0=co.
Similarly, /, = do is set to a certain value.

After setting in this way, when the sensor drive device is started, the motor 19°25 shown in FIG. Corresponding to the approaching signal, j'o=d
If o>O, the motor 19 is rotated left or right.

So '1sbl was measured in the first l/2f0 seconds,
@1::el-06, mu = = d, -d (1 is calculated and divided in the correction signal generator 31. Then, the signal of e is
□The signal of f is sent to the D/A converter 33 and the D/A converter 32
is input at the end of the first period 1/2 fo seconds using the reset pulse of the timing pulse generator 46 in the extreme value generator 34.

The D/A converter 33.32 operates for a certain period of time τ seconds (τ<l/2f
0) and rotates the motors 19 and 25. Therefore, timers are set so that the D/A converters 33 and 32 continue to output for τ seconds.

Immediately after this first C8,f is input to the D/A converter 33.32, the reset pulse of the timing pulse generator 46 in the extreme value detector 34 is used to
Replace o with C1 and replace do of comparator S8 with d.

In this manner, by remanipulating the above-described actions, the sensor drive device continues to operate so as to make the relative position between the sensor head 2 and the object surface 7 appropriate.

According to such a device, the sensor head 2 can maintain a constant distance and perpendicular positional relationship with respect to any target surface that can reflect ultrasonic waves. (1) A constant distance with respect to any plane For example, it can be used as a sensor for painting robots, welding robots, etc. that work at a fixed angle.

(2) When the sensor head moves so as to maintain an appropriate relative position with respect to a plane, the plane position and angle can be detected from the amount of movement.

According to the present invention, there is provided a sensor head in which an emitting section that emits ultrasonic waves toward a target surface and a receiving section that receives ultrasonic waves reflected from the target surface are disposed axially symmetrically in opposition to each other;
A means for rotating the sensor head at a constant speed around the axis, and analyzing fluctuations in the magnitude of reflected waves received by the receiver and outputting the distance and angle between the sensor head and the target surface, respectively. The present invention is industrially extremely useful because it provides an ultrasonic sensor device that outputs the relative position and angle with respect to the target object surface, respectively, by using ε having a position calculation circuit.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention, Fig. 2 is a partially enlarged view showing the corrected signal generator of Fig. 1, and Fig. 3 shows the extreme value detector of Fig. 2. Partial enlarged view shown, No. 4
The figure shows the characteristics of the ultrasonic emitter shown in Fig. 1, Fig. 5 is a side view showing the case where the sensor head is perpendicular to the target surface and at a predetermined distance, and Fig. 6 shows the distance shown in Fig. 5. 7 is a diagram showing the intensity of the reflected wave in FIG. 6, and FIGS. 8 and 9 are side views showing the case where the sensor head is tilted at a predetermined distance from the target surface. Figures io and 11 are explanatory diagrams showing the case where the distance changes uniformly when the sensor head is tilted with respect to the target surface, and Figure 12 is a line showing the intensity of the reflected wave in Figure 5. Figure 13 is a diagram showing the intensity of the reflected wave in Figure 6, Figures 5 and 14 are diagrams showing the intensity of the reflected wave in Figures 8 and 9. 12 is a diagram showing the intensity of reflected waves shown in FIG. 12 and FIG. 11. FIG. 9 1... Central axis, 2... Sensor head, 3... Emitting section, 4... Receiving section, 5... Route, 6... Route,
7...Target surface, 18...Fist mount, 19...Motor,
20.21... Coil, 22, 23... Coil, 24... Motor, 25... Motor, 26... Signal generator, 27.
...Amplifier, 28...Filter, 29...Detector,
31... Correction signal generator, 32... D/A converter,
33...D/A converter, 34...Extreme value detector,
35... Adder, 36... Subtractor, 37... Subtractor, 38... Subtractor, 39... A/D converter, 4o
...Maximum value register, 41...Comparator, 42...
Signal selection gate, 43... Comparator, 44... Minimum value register, 45... Signal selection gate, 46... Timing pulse generator. Applicant's sub-agent Patent attorney Suzue Takehiko 1' knee 0 Figure 8 1 Figure 10 Figure 9 Figure n II Figure 12 Figure 14 Figure 13 Figure 15

Claims (1)

[Claims] A sensor head includes a transmitter that emits ultrasonic waves toward a target surface and a receiver that transmits ultrasonic waves reflected from the target surface in an axially symmetrical arrangement; It is characterized by comprising means for rotating at a speed, and a position calculation circuit that analyzes fluctuations in the magnitude of reflected waves received by the receiving section and outputs the distance and angle between the sensor head and the target surface, respectively. Ultrasonic sensor device.