JPH06137850A - Ultrasonic three-dimensional robot position / orientation measuring device and its measuring method - Google Patents

Abstract

(57) [Abstract] [Purpose] Measuring the position and orientation of a robot using three ultrasonic wave transmitters and three or four wave receivers by applying distance measurement by measuring the propagation time of ultrasonic pulses. By doing
A simple and inexpensive robot position / orientation measuring device is configured, and accuracy is improved. [Structure] When measuring the three-dimensional position / orientation of the robot by ultrasonic waves, the robot is attached to the hand 2 of the robot 1
Ultrasonic transmitters T _{1 to} T ₃ for emitting ultrasonic pulses using individual electric sparks, and three receivers R ₁ to R ₁ fixed to predetermined positions for receiving ultrasonic pulses from the ultrasonic transmitters. R ₃
Is provided, and the three-dimensional position / orientation of the robot is measured by triangulation using the distance obtained by measuring the propagation time of the ultrasonic pulse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ultrasonic three-dimensional position / orientation measuring apparatus for a robot and a measuring method thereof.

[0002]

2. Description of the Related Art Conventionally, the following can be cited as technical literature in such a field. (1) Report of "Survey and Research on Standardization of Industrial Robots", Japan Industrial Robot Manufacturers Association, (198)
8) Pages 6 to 31 (2) Masaki Saito: Check system for confirming the actual behavior of the robot, automation technology, Vol. 18, No.
11, (1986) pp. 117-122 (3) K. Lau, R .; J. Hocken and
W. C. Height: Automatic case
r tracking interferometer
system for robot metrolo
gy, Precision Engineering
g, Vol. 8, No. 1, (1986) pp. 3-8 (4) GP-8-3D Sonic Digitize
r Operator's, Manual, Scie
nce Accessories Corp. , (19
85) pp. 1-85 (5) Mitsuo Goto, Yoshihisa Tanimura, Toshiro Kurosawa: Coordinate measurement system by tracking laser interferometer-Basic design and trial production of elements-, 1988 Autumn Meeting of Precision Engineering Society Conference Shu, (1988) pp. 315 to 316 (6) Large-scale project of the Agency of Industrial Science and Technology, Extreme work robot research and development technical report, Extreme work robot technology research association,
(1990) pp. 168 to 173 (7) Akira Shimokawa, Aki Ma: Measurement of three-dimensional coordinates by multiple phase differences of intermittent ultrasonic waves, Journal of Precision Engineering, Vol. 5
3, No. 9, (1987) 72 to 77 pages (the number of pages in a regular page is 1408 to 1413 pages) (8) Mami Matsukawa, Takahiko Otani: Influence of discharge circuit conditions in discharge impulse sound source, Ultrasonic Research Group materials, (198
8) Pages 37-44 (9) Ken Sasaki, Katsuhisa Ono, Masaharu Takano: Research and development of high-precision ultrasonic sensors for robots, precision machinery, Vo
l. 51, No. 6, (1985) pp. 142-147.
Pages (The number of pages in the regular page is 1238 to 1243) (10) D. E. Whitney, C.I. A. Lozin
ski and J. M. Rourke: Indust
Rial Robot Forward Calibr
ation Method and Results,
Transactions of the ASME,
Journal of Dynamic System
s, Measurement and Contro
1, Vol. 108, No. 1, (1986) page 1-
Page 8 (11) Nobuyuki Furuya, Hiroshi Makino: Calibration of SCARA robot specifications by teaching, precision machinery, Vol.
49, No. 9, (1983) pages 69 to 74 (the number of pages in a regular page is 1223 to 1228) The robot is used not only for simple work such as pick and place, but also for work that requires high precision such as assembly. Nowadays, accurate evaluation of robot motion performance is an important issue for both manufacturers and users.

In particular, evaluation of the absolute positioning accuracy of the robot is important because it is a prerequisite for off-line programming, which is expected as an alternative to manual teaching. However, at present, a measuring device for measuring the position / orientation of a robot moving in a wide three-dimensional space while taking an arbitrary trajectory in a non-contact manner in real time and with high accuracy is not in practical use at present.

Therefore, at present, as a motion performance evaluation of a robot, it is generally performed to evaluate the repetitive positioning accuracy at several points in space by a proximity sensor.

[0005]

However, this method has relatively high measurement accuracy but is static measurement, and only local data can be obtained, which is not sufficient for evaluating the motion performance of the robot. Absent. On the other hand, as a three-dimensional coordinate non-contact measuring device, a system using LED light, a laser beam, and an ultrasonic wave has been researched, and a part thereof has been commercialized.

Of these, the former two perform triangulation using angles, as will be described later, and therefore the position accuracy is difficult to obtain in a wide measurement range. Moreover, since an image processing device and a laser interferometer are required, the system is large and expensive, and it is difficult for each manufacturer and user to own their own system. There is a report that the laser is used for triangulation, but the system is expensive and not suitable for robot measurement.

By the way, the position repeatability of the current industrial robot is ± 0.3 m for the 6-DOF vertical articulated type robot.
Although it is about m, the absolute positioning accuracy is not usually shown in the catalog, and it is said that robots other than the DD robot and SCARA robot with relatively high accuracy are considerably bad. Causes of this include dimensional error of the mechanism such as link length, misalignment of each axis, backlash of the speed reducer, and the like. Therefore, the coordinates in the three-dimensional space of about 2 m square are ±
If there is a system that can easily and inexpensively measure with a measurement accuracy of about 0.3 mm, it is effective for evaluating the robot's motion performance such as absolute positioning accuracy, posture accuracy, path repeatability, absolute path accuracy, and speed accuracy.

Since the ultrasonic distance meter uses a sound velocity that is easily affected by temperature, local fluctuations of air, etc., when the measurement is performed in an ordinary room which is not hermetically sealed, the distance measurement accuracy is slightly deteriorated. However, the accuracy is within the allowable range, and it is considered that the measurement system using ultrasonic waves is sufficiently effective for the performance evaluation of the robot. This method uses triangulation using distance as a measurement principle, but there is another measurement method that uses triangulation using angle. As an example of triangulation using an angle, consider a system in which a beam from a laser head is reflected by a mirror rotatable around two axes installed at a reference point and a target such as a corner cube is irradiated with the beam.

In this case, the positional deviation of the beam due to the movement of the target is detected by the optical position detector, and the rotation angle of the mirror is constantly controlled so as to eliminate it. The method of knowing the corner and calculating the position is adopted. In this system, for example, in order to measure a target 1 m away from the reference point with an accuracy of ± 0.2 mm, tan ⁻¹ (± 0.2 / 1000) = ± 0.01
High angle measurement accuracy of ° is required. Further, even if the detector has this angle accuracy, extremely advanced control technology is required to accurately track the target in real time with this angle accuracy, and the development cost of the system becomes enormous. Become.

Further, as a method of measuring a distance using ultrasonic waves, there is a method of intermittently transmitting ultrasonic waves of several tens of wavelengths and obtaining the distance from the phase difference between the transmitted waveform and the received waveform. This method requires the transmission of several types of amplitude modulated sound waves,
Further, since it is necessary to remove unnecessary reflected waves, there is a problem that it takes time to measure the coordinates once. The present invention is
In view of the above situation, by applying the distance measurement by measuring the propagation time of the ultrasonic pulse and measuring the position / orientation of the robot by using three transmitters, three or four wave receivers, An object of the present invention is to provide an ultrasonic three-dimensional position / orientation measuring apparatus for a robot, which can be simply constructed at low cost, and can improve accuracy, and a measuring method thereof.

[0011]

In order to achieve the above object, the present invention provides: (A) In a robot three-dimensional position / orientation measuring apparatus using ultrasonic waves, three electric sparks attached to a robot hand are provided. The ultrasonic wave generator that generates the ultrasonic wave pulse used, the three wave receivers that are fixed at predetermined positions to receive the ultrasonic wave pulse from the ultrasonic wave oscillator, and the ultrasonic wave propagation time are obtained. By triangulation using distance,
A measuring means for measuring the three-dimensional position / orientation of the robot is provided.

Further, it has the following subordinate structure. (1) The receiver uses a condenser microphone. (2) It has a device for adjusting the depression and elevation angle and the turning angle of the wave receiver. (3) A transmission time detection circuit for detecting the transmission time of the ultrasonic transmitter is provided. (4) A / D converter that converts a received analog signal from the wave receiver into a digital signal, the transmission time detection circuit connected to the A / D converter, and an operation connected to the A / D converter A processing device is provided.

(5) A sound velocity monitoring unit connected to the arithmetic processing unit is provided. (B) In the three-dimensional position / orientation measuring method of a robot using ultrasonic waves, an ultrasonic wave transmitter that emits ultrasonic pulses using three electric sparks is installed in the robot hand, and the ultrasonic wave from the ultrasonic wave transmitter is transmitted. Sound wave pulse is fixed in place 3
The three-dimensional position / orientation of the robot is measured by measuring the propagation time of the ultrasonic pulse, which is received by each wave receiver, and by triangulation using the distance.

Further, it has the following subordinate structure. (1) While detecting the transmission time of the ultrasonic transmitter, the receiver detects the first zero-cross point after the amplitude of the pulse wave due to electric spark exceeds a threshold value, and based on this, the ultrasonic wave is detected. Measure the transit time of the pulse. (2) Sound velocity correction is performed near the measurement position.

(3) The distance between the wave receivers is measured using the wave receivers. (C) In a three-dimensional position / orientation measuring device for a robot using ultrasonic waves, an ultrasonic transmitter for generating ultrasonic pulses using three electric sparks attached to the hand of the robot, and the ultrasonic transmitter Calculate four variables of X, Y and Z coordinates of the ultrasonic transmitter and the speed of sound in the measurement space by measuring the propagation time of the ultrasonic pulse and four receivers fixed at predetermined positions for receiving the ultrasonic pulse. However, it is provided with a measuring means for measuring the three-dimensional position / orientation of the robot by triangulation using the distance.

Further, it has the following subordinate structure. (1) The wave receiver is a condenser microphone. (2) A device for adjusting the depression angle and the turning angle of the wave receiver is provided. (3) Electric spark timing control board that generates electric sparks from the ultrasonic transmitter, and a four-channel distance calculation that reads the transmission time from the transmitter and calculates the distance based on the received signal from the receiver A board and an arithmetic processing unit connected to these are provided.

(4) A sound velocity monitoring unit connected to the arithmetic processing unit is provided. (D) In the method of measuring the three-dimensional position / orientation of a robot using ultrasonic waves, an ultrasonic wave transmitter that emits ultrasonic pulses using three electric sparks is installed in the robot hand, and the ultrasonic wave from the ultrasonic wave transmitter is transmitted. Sound wave pulse is fixed in place 4
It is received by each of the wave receivers, the propagation time of the ultrasonic pulse is measured, four variables of the X, Y, Z coordinates of the ultrasonic transmitter and the sound velocity in the measurement space are calculated, and a triangle using the distance is calculated. The 3D position / orientation of the robot is measured by surveying.

Further, it has the following subordinate structure. (1) While detecting the transmission time of the ultrasonic transmitter, the receiver detects the first zero-cross point after the amplitude of the pulse wave due to electric spark exceeds a threshold value, and based on this, the ultrasonic wave is detected. Measure the transit time of the pulse. (2) The sound velocity in the measurement space is estimated and calculated from the propagation time of the ultrasonic pulse from the ultrasonic transmitter to the four receivers.

(3) Using the wave receiver, the distance between the wave receivers is measured to calibrate the initial coordinate system. (4) A sound velocity monitoring unit is used in the calibration of the initial coordinate system.

[0020]

According to the present invention, as shown in FIG. 1, ultrasonic transmitters T _{1 to} T ₃ for generating ultrasonic pulses using three electric sparks attached to the hand 2 of the robot 1 and the ultrasonic transmitters thereof. _Three ultrasonic wave receivers R _{1 to} R ₃ fixed at predetermined positions for receiving the ultrasonic wave pulses from the ultrasonic wave transmitters T _{1 to} T ₃ are provided, and the propagation time of the ultrasonic wave pulse is measured. Three variables of the X, Y, Z coordinates of the sound wave transmitter and the sound velocity in the measurement space are calculated, and the three-dimensional position / orientation of the robot is measured by triangulation using the distance.

Also, as shown in FIG.
Of the ultrasonic transmitters T _{1 to} T ₃ for generating ultrasonic pulses using three electric sparks attached to the hand 46 of the robot, and a predetermined position for receiving the ultrasonic pulses from the ultrasonic transmitters T _{1 to} T _3. Four wave receivers R _{1 to} R ₄ fixed to the robot are provided, the propagation time of the ultrasonic pulse is measured, and the three-dimensional position / orientation of the robot is measured by triangulation using the distance.

Therefore, since inexpensive ultrasonic transmitters and receivers are used, the structure can be simplified and inexpensive, the sound velocity in the measurement space is always accurately calculated, and the triangulation using the distance is performed. The accuracy can also be obtained at the level required for robot measurement.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a principle diagram of a measurement system using ultrasonic pulses showing a first embodiment of the present invention, FIG.
Is a partially exploded perspective view of the transmitter of the measurement system, FIG. 3 is an electric circuit diagram of the transmitter of the measurement system, FIG. 4 is a perspective view of the receiver of the measurement system, and FIG. FIG. 5 is a received pulse waveform diagram of an electric spark discharge according to the present invention.

Since the robot takes various positions and postures,
The ultrasonic transmitter is preferably an omnidirectional point sound source from the viewpoint of measurement accuracy and directivity. Therefore, in the present invention, an electric spark that can approximate an omnidirectional point sound source is used as the ultrasonic transmitter. As shown in FIG. 2, the ultrasonic transmitter 10
Has a support portion 11a in which V grooves 12 are formed at both ends of a stand 11 made of bakelite.
By pressing the holder 14 against the groove 12 with the screw 15, a gap 25 (for example, 30 μm) is formed in the central portion.
m), the discharge needle 13 is fixed. By the way,
In FIG. 2, L ₁ is 80 mm, L ₂ is 10 mm, and φ ₁
Is 1 mm.

Therefore, as shown in FIG.
A shocking high voltage is applied to. That is, the DC voltage 30V of the power source 21 is applied to the capacitor 22 (44 μF),
The accumulated charges are triggered by the FET 23 to perform switching, and the intermittent current is caused to flow to the primary side of the ignition coil 24 (coil ratio is 1: 100), so that the secondary side of the ignition coil 24 has a shocking high level. A voltage is generated to cause an electric spark in the gap 25. Then,
Along with that, an ultrasonic pulse is generated.

As shown in FIG. 4, the wave receiver uses a condenser microphone 31 having a resonance frequency of 85 kHz. Three
3 is a support shaft of this condenser microphone 31,
Further, the support shaft 33 is supported by an L-shaped support plate 34, and the support plate 34 has a support shaft 35. Therefore, the condenser microphone 31 is driven by a DC servomotor (not shown), and the depression / elevation angle can be adjusted by the support shaft 33. Further, the condenser microphone 31 including the support shaft 33 is driven by a DC servo motor (not shown), and the support shaft 35 can adjust the turning angle. That is,
The condenser microphone 31 can adjust the direction of the wave receiver. Here, for example, the wave receiving surface of the condenser microphone 31 is configured as a circular surface having a diameter of 26 mm.

FIG. 5 shows a received waveform of an ultrasonic pulse generated by an electric spark. The waveform has a sharp rise enough to catch the moment when the ultrasonic pulse arrives, and its sound pressure is sufficient for distance measurement of about 2 m necessary for application to a robot. Microscopic observation of the electrode surface after 100,000 discharges revealed a slight crater-like wear, but the change in the received waveform due to electrode wear was very small and did not affect the measurement accuracy. Met.

The distance measuring method will be described in detail below. As shown in FIG. 5, the rangefinder of the present invention uses the first zero-cross point after the amplitude of the pulse wave exceeds the threshold value as the time when the ultrasonic pulse arrives, so that the measurement distance is changed. It is difficult to be affected by the amplitude. Since this distance meter multiplies the arrival time of the ultrasonic pulse by the sound velocity to obtain the distance, the time when the ultrasonic pulse propagates over a known fixed distance (about 1350 mm) is monitored in real time to obtain the accurate sound velocity.

The measurement accuracy of this range finder was verified using an NC machine tool having a positioning accuracy of 1 μm as a calibration standard. As shown in FIG. 6A, the transmitter T is fixed to the bed of the NC machine tool, and the bed is moved every 50 mm in one axis direction by 800 mm.
Positioning was performed with an accuracy of 1 μm at each point up to mm, and the distance between the transmitter T and the wave receiver R at each point was calculated 1000 times with this range finder.

The receiver R is placed approximately 20 from the position of the first transmitter.
Approximately 1200 m when installed 0 mm apart (Case A)
The measurement was carried out for the case where they were installed at a distance of m (case B). FIGS. 6B and 6C show the results of the relative coordinates obtained by subtracting the measurement distance at the origin from the measurement distance at each point with the first measurement point as the origin. Where ● is 10
The average value Ex of the measurement error in the measurement of 00 times, and the symbol ◯ indicate the standard deviation σx.

The average value of the measurement error of this rangefinder is within ± 0.1 mm within a measuring range of 1 m, and within ± 0 mm within a measuring range of 2 m.
Within 3 mm, the standard deviation is 0.1 in the measuring range of 1 m.
It was 0.2 mm or less in a measuring range of 2 mm or less.
The cause of the measurement error is that the place where the measurement is performed and the place where the distance meter for sound velocity correction is installed are separated by about 1 m for the sake of the experiment, and the measurement was performed in the factory where constant temperature and air stabilization were not considered at all. This is because the temperature / humidity, air flow, etc. were different at both places, and the sound velocity was not corrected accurately.

The variation of the measurement error is caused by the fluctuation of air in the measurement space. For comparison, this rangefinder including the rangefinder for sound velocity correction was installed in the closed wind tunnel device.
A distance of about 2 m was measured 1000 times over about 4 hours in an approximately windless state. As a result, the standard deviation of the measurement error is 0.
07mm, the difference between the maximum and minimum measurement error is 0.34m
Higher accuracy was obtained compared to the case where the m was not closed. From this, it is understood that the variation in the measurement error is caused by the fluctuation of the air in the measurement space, not the variation in the discharge position of the electric spark as the transmitter.

Therefore, it is considered that the accuracy of the distance meter of the present invention is further improved if the sound velocity is corrected near the measurement position and the air in the measurement space is stabilized. Next, the principle of three-dimensional position / orientation measurement of the robot of the present invention will be described. Here, the principle of position / orientation measurement using three transmitters and three receivers will be described.

As shown in FIG. 7, three wave receivers R _{1 to} R
₃ and 3 transmitters T _{1 to} T ₃ are arranged, and 3 transmitters T
First transmitter of _{1 ~T 3 T 1 (X 1} , Y 1,
Let L _i be the measured distance between Z ₁ ) and the receiver R _i (x _i , y _i , z _i ). Here, i = 1 to 3. In this ^{_{case, (X 1 -x i) 2}} + (Y 1 -y i) 2 + (Z 1
By solving -z _i ) ² = L _i ² , the three-dimensional position of the oscillator T ₁ is obtained.

The remaining transmitters T ₂ (X ₂ , Y ₂ , Z ₂ ),
The three-dimensional position of the transmitter T ₃ (X ₃ , Y ₃ , Z ₃ ) can be obtained in the same manner. Here, assuming that the center of gravity G of the triangle formed by the three transmitters and the tip of the hand are positioned before the measurement, the coordinates of the center of gravity G are measured by the transmitters T ₁ , T ₂ , and T ₃ . It can be calculated and obtained from the coordinates.

Next, the three-dimensional posture calculation is performed as follows. As shown in FIG. 7, the reference vectors e ₁ , e ₂ , e
Take ₃ and let this represent the pose of the robot. First,

[0037]

[Equation 1]

Calculate q is a transmitter T ₁ , T ₂ , T ₃
And a vector orthogonal to p ₁ on the plane formed by the tip G of the hand. Using these, the reference vector e ₁ ,
e ₂ and e ₃ can be obtained as follows. e ₁ = p ₁ / | p ₁ | e ₂ = q / | q | e ₃ = e ₁ × e _{2 As described} above, the position / orientation of the robot is 3 transmitters and 3 receivers. It can be uniquely obtained by using it.

When converting the measured position / orientation into values in the robot coordinate system (X _R , Y _R , Z _{R in} FIG. 7), it is necessary to calibrate the relative positional relationship between the robot coordinate system and the measurement coordinate system. Although this occurs, various methods have been proposed as this method in which the robot is made to perform positioning at several points and the measured coordinate value at each point and the reading of the encoder of each joint are used. Next, the outline and features of the ultrasonic three-dimensional robot position / orientation measuring system according to the present invention will be described.

As shown in FIG. 8, three transmitters T _{1 to} T ₃ for generating ultrasonic pulses by the electric sparks described above are provided, and each transmitter T _{1 to} T ₃ is connected to a transmission time detection circuit 41. To be done. The transmission time detection circuit generates a trigger based on the transmission time of each of the transmitters T _{1 to} T ₃ and transmits it to the A / D converter 42. On the other hand, the ultrasonic wave pulses transmitted from the _three transmitters T _{1 to} T ₃ are received by the _three wave receivers R _{1 to} R ₃ , and the received ultrasonic wave pulses are A / D converter 42. And converted into a digital signal.

The digital signal is processed by the arithmetic processing unit 44.
At, arithmetic processing is performed. In addition, the arithmetic processing device 4
An output signal from a sound velocity monitoring unit 43 provided in the vicinity of the measurement position is input to 4 and the sound velocity is corrected in the vicinity of the measurement position. Further, in the present invention, the wave receiver R is configured to be rotatable.

That is, since the directivity of the wave receiver is as sharp as a half angle of 6 °, as shown in FIG. 4, the wave receiver is horizontally driven to rotate the support shaft 33 by rotating the support shaft 35. Thus, it is made rotatable in the vertical direction and faces the front of the transmitter T. This solves the problem that the measurable space is limited due to the directivity of the receiver common to the system using the conventional fixed ultrasonic receiver, and with higher accuracy than those. The measurable space has been expanded.

Furthermore, by directing the wave receiver with a fairly sharp directivity to the front of the oscillator, it is possible to prevent noise in the ultrasonic frequency range from coming from other than the oscillator. Next, the radius r for arranging the oscillator shown in FIG. 7 will be described. Here, in consideration of real-time measurement, the positions of the three transmitters are measured while the wave receivers are not directed to the front faces of the three transmitters one by one, but with the front ends of the tips G of the hands.

Therefore, when the allowable deflection angle at which the wave receiver can accurately measure the distance to the transmitter is α and the distance from the wave receiver to the tip G of the hand is L, the radius r must satisfy r <Ltan α. There is. Here, L is | R ₂ G |. On the other hand, the larger the radius r, the smaller the attitude measurement error. As an example, in FIG. 7, when the position measurement error of the oscillator T ₁ is δd, e ₁ is measured with an angle error of δθ = tan ⁻¹ (δd / r).

The ultrasonic range finder of the system of the present invention has an accuracy of measuring the size of the receiver if the receiver is facing the front of the transmitter within the error of the half angle of the receiver of 6 °. The influence was about 0.2 mm in the measurement range of 500 mm. Therefore, in the system of the present invention, this effect is removed by making the receiver face the front of the tip G of the hand with an error of about ± 3 ° based on the received waveform and sound pressure.

Therefore, in this system, α = 3
Condition r <26.0 assuming L = 500 mm
From mm, r = 25.0 mm. At this time, δd =
Assuming 0.1 mm, the attitude measurement error is δθ = 0.2
Estimated at 3 °. Next, the calibration of the initial coordinate system is performed as follows. Prior to measurement, it is necessary to know the relative positional relationship of the three wave receivers. In the system of this embodiment, since the receiver itself can actively transmit ultrasonic pulses as a vibrating membrane, the receiver and receiver exchange pulses and the relative position is determined by measuring the mutual distance.

Therefore, as shown in FIG. 9, three wave receivers R _{1 to} R ₃ are arranged at appropriate positions, and R ₁ (0,
0, 0), R ₂ (a, 0, 0), R ₃ (b, c, 0), and the mutual measurement distances between the receivers are p, q, r, a = p b = (r ²⁻ q ² + p ² ) / 2p, c = √ {r ² − [(r ² −q ² + p ² ) / 2p] ² } is used to obtain a, b, and c, and the reference coordinate system is calibrated.

Since the receiving surfaces were kept parallel during the measurement of the distance between the wave receivers, the size and directivity of the wave receivers did not affect the measurement accuracy. As described above, since the system of this embodiment calibrates internally, it is not necessary to calibrate the initial coordinate system from the outside, and since the receiver can be arranged at any position, it is possible to respond to changes in the measurement target. It has a great flexibility.

Next, a verification experiment of the position / orientation measurement accuracy according to this embodiment was conducted. Here, FIG. 10A shows the experimental conditions, and FIG. 10B shows the experimental results. That is, as shown in FIG. 10A, the arm tip positions (accuracy ± 0.06) at several points on the circular orbit of the space rotating arm.
mm) and the arm posture (accuracy ± 30 arcsec) as calibration standards, and by measuring them, the three-dimensional position / orientation measurement precision of the system of the present invention was verified. In addition,
A DD motor with a resolver (positioning accuracy ± 30 arcsec) was used to drive the arm.

Although the movement of the arm is performed in the plane, the measurement is three-dimensional because it does not coincide with the XY plane of the measurement coordinate system. At the time of measurement, care was taken to make both planes parallel by using a surface plate, a jig, and the like. It can be confirmed from the measurement result of the Z coordinate shown in FIG. 12 that the parallel accuracy was relatively good. The coordinates of the center of gravity (tip of the hand) G were obtained by sequentially measuring the positions of the three transmitters. Measurement X of the first two center of gravity G
By matching the Y coordinate and the arm coordinate, a two-dimensional coordinate conversion formula from the coordinate system of the measurement system to the arm coordinate system was obtained. From the third point below, the measurement coordinates were converted into arm coordinates according to this formula. The posture angle is shown in FIG.
It was obtained by obtaining P ₁ in (a) and similarly converting this XY component into the arm coordinate system.

The results are shown in FIGS. 10 (b), 11 and 12. In FIG. 12, deviations from the average value of the measured Z coordinates of −22.1 mm are shown in the columns of Z _M and E _Z. Figure 10
In (b), the solid line shows the accurate position / orientation of the arm obtained from the reading of the resolver, and the broken line shows the measurement result by enlarging the measurement error of the system of the present invention by the magnification shown in the figure. It is a thing. The position measurement error was 0.4 mm or less. Considering that the standard deviation is small,
It is considered that the accuracy of position measurement is improved if the accuracy of coordinate conversion is improved by matching not only the point and the second point but also more points.

The attitude angle measurement error was 0.4 ° or less, and the standard deviation was 0.2 ° or less. In FIG. 11, θ _A is the arm posture angle (calibration standard), θ _M is the measured posture angle, and Eθ and σθ are the error and standard deviation of the measured posture angle. Also, in FIG. 12, (X, Y, Z) _A
Is the arm coordinate (calibration standard), (X, Y, Z) _M is the measured coordinate, E _X , E _Y , E _Z is the error of the measured coordinate,
σ _X , σ _Y , σ _Z are standard deviations of the measured coordinates,
The position G and the arm posture angle were measured 100 times for each data.

From the above results, it was confirmed that the measuring system of the first embodiment of the present invention has a possibility of being able to cope with the actual measurement of the robot. Next, a second embodiment of the present invention will be described in detail with reference to the drawings. FIG. 13 is a principle diagram of a measuring system using ultrasonic pulses showing a second embodiment of the present invention, and FIG. 14 is an explanatory diagram of a principle of measuring a three-dimensional position / orientation of a robot showing a second embodiment of the present invention. 15 is a block diagram of the three-dimensional position / orientation measuring system of the robot.

In this embodiment, as a method for calculating three-dimensional coordinates, a method for accurately estimating and calculating the sound velocity in the measurement space as a parameter using four wave receivers (hereinafter referred to as sound velocity estimation method) was developed. Is adopted. FIG.
As shown in FIG. 14, four wave receivers R _{1 to} R ₄ are arranged, and a first transmitter T ₁ (X ₁ , Y ₁ , Z ₁ ) provided on the hand 46 of the robot 45, Let t _{i be} the measured value of the ultrasonic pulse propagation time between the receivers R _i ( _i = 1 to 1).
4). At this time, the following four expressions are established with the sound velocity as C.

X ₁ ² + Y ₁ ² + Z ₁ ² = (C · t ₁ ) ² (1) (X ₁ −a) ² + Y ₁ ² + Z ₁ ² = (C · t ₂ ) ² (2) ( ^{_{X 1 -b) 2 + (Y}} 1 -c) 2 + Z 1 2 = (C · t 3) 2 ... (3) (X 1 -d) 2 + (Y 1 -e) 2 + (Z 1 -f ) ² = (C · t ₄ ) ² (4) (1)-(2), (1)-(3) and (1)-
From the equation (4), T ₁ (X ₁ , Y ₁ , Z ₁ ) is represented by the following equation.

[0056]

[Equation 2]

The inverse matrix is obtained prior to measurement when the four wave receivers are not on the same plane. By substituting the equation (5) into the equation (1) again, a quadratic equation for C ² is created, and C can be easily obtained analytically (calculation formula is omitted). By substituting this C into the equation (5), T ₁ (X ₁ ,
Y ₁ , Z ₁ ) is obtained. In this method, the sound velocity in the measurement space is used as a variable for real-time calculation, so that accurate sound velocity correction can always be performed. Further, since the fourth wave receiver is installed above the measurement space, the z-coordinate measurement accuracy is higher than the method using only three wave receivers. Furthermore, since a sound velocity correction sensor is not required separately, the system can be simplified.

Similar to the above method, the coordinates T ₂ (X ₂ , Y ₂ , Z ₂ ) and T ₃ (X ₃ ,
Y ₃ , Z ₃ ) can also be determined. Here, assuming that the center of gravity of the triangle formed by the three transmitters and the tip G of the hand are positioned so as to coincide with each other before the measurement, the coordinates of G are the measured coordinates of T ₁ , T ₂ , and T _3. It can be calculated and obtained.

As shown in FIG. 14, the reference vectors e ₁ ,
Let e ₂ and e ₃ be taken to represent the posture of the robot. First,

[0060]

[Equation 3]

Calculate q is T ₁ , T ₂ , T ₃ and G
Is a vector orthogonal to e ₁ on the plane constituted by
Using these, the reference vector can be obtained as follows: e ₁ = p ₁ / | p ₁ | e ₂ = q / | q | e ₃ = e ₁ × e ₂ (7) As described above, the position / orientation of the robot can be uniquely obtained by using three transmitters and four wave receivers.

Next, the structure of the measuring system will be described. As the wave receiver, the same one as shown in FIG. 4 of the first embodiment is used. That is, since the directivity of the wave receiver is as sharp as a half-angle of 6 °, the wave receiver can be rotated horizontally and vertically by the DC servo motor so that the wave receiver always faces the front. This eliminates the problem that the measurable space is limited due to the directivity of the receiver that is common to the conventional systems that use fixed ultrasonic receivers. The space to be played was expanded.

As shown in FIG. 15, in the measurement system of this embodiment, the arrival time of the ultrasonic pulse from the transmitter 60 to the receiver 64 is detected in real time by hardware by the 4-channel arrival time measurement board. To configure.
The arithmetic processing unit 50 has a high precision timer 52, an electric spark timing control board 53, a sound velocity calculation board 54, a four-channel arrival time measurement board 55, an expansion unit 51 having a parallel interface and an interrupt 56.

In response to a signal from the electric spark timing control board 53, a high voltage is applied from the electric spark power source 58 to the transmitter 60 via the ignition circuit 59 to emit an ultrasonic pulse. The transmission time from the transmitter 60 is detected by the transmission time detector 57, and the transmission time is input to the high precision timer 52 and the 4-channel arrival time measuring board 55.

On the other hand, when the ultrasonic wave pulse is received by the four wave receivers 64, the received signal is read into the 4-channel arrival time measuring board 55 via the preamplifier 63.
Further, a sonic velocity monitoring unit 62 is connected to the sonic velocity calculation board 54 via a preamplifier 61, and is configured to monitor the sonic velocity. Further, the arithmetic processing unit 70
Is connected to an expansion unit 71 having a counter 72, a D / A converter 73, a parallel interface and an interrupt 74, and the counter 72 and the D / A converter 73 are connected to a motor signal distribution circuit 75. The circuit 75 is connected to a motor drive circuit 76, and the motor drive circuit 76 is connected to a DC servo motor 77. Note that parallel communication is performed between the parallel interface and interrupt 56 and the parallel interface and interrupt 74. Further, each wave receiver can be horizontally and vertically rotated by two DC servo motors.

Therefore, the arithmetic processing unit 50 reads the arrival time of the transmitted signal from the 4-channel arrival time measuring board 55 and calculates the position of the transmitter according to the above-mentioned principle. Next, from the positions of the transmitters T _{1 to} T ₃ , the wave receivers R _{1 to} R ₄ are placed.
It calculates the horizontal and vertical rotation angles and sends them to the parallel boat. The arithmetic processing unit 70 includes the wave receivers R ₁ to R ₁ .
The DC servomotor 77 that rotates R ₄ is controlled, and when the motor command order is sent from the expansion unit 51, an interrupt occurs and the target value of the rotation angle is updated.

Prior to measurement, it is necessary to know the relative positional relationship of the _four wave receivers R _{1 to} R ₄ . Here, since the wave receiver itself can actively transmit ultrasonic pulses as a vibrating film, the relative position can be obtained by exchanging the pulses between the wave receivers and measuring the mutual distance. Therefore, as shown in FIG. 16, four wave receivers R _{1 to} R ₄ are arranged at appropriate positions, and R ₁ (0,0,0) and R ₂ (a,
0,0), R ₃ (b, c, 0), R ₄ (d, e, f), and the mutual measurement distances between the receivers are p, q, r, s, t,
As u, a = p b = (r ² −q ² + p ² ) / 2p c = √ {r ² − [(r ² −q ² + p ² ) / 2p] ² } d = (s ² −t ² + a ² ) / 2a e = (s ² −u ² + b ² + c ² −2bd) / 2c f = √ (s ² −d ² −e ² ) so that a, b, c, d,
Obtain e and f and calibrate the reference coordinate system.

As described above, since this measuring system calibrates internally, it is not necessary to calibrate the initial coordinate system from the outside, and since the receiver can be arranged at any position, it is possible to cope with changes in the measuring object. It has the characteristic of having great flexibility. Next, a verification experiment of three-dimensional position measurement accuracy according to this example was conducted. Here, the measurement accuracy of this measurement system was verified using an NC machine tool with an accuracy of 1 μm.

The transmitter is fixed to the chuck of the NC machine tool, and as shown in FIG. 17, three wave receivers R ₁ to R ₁ are attached to the bed.
Fix R ₃ and fix the fourth receiver R ₄ above the bed. The oscillator was stationary on 36 grid points and the coordinates of each point were measured. Where X, Y, Z are NC coordinate systems,
X ', Y', and Z'indicate measurement coordinate systems. Experimental results of the measurement error and the standard deviation of the measurement coordinates are shown in FIGS. 18 (a) and 18 (b), respectively. In analyzing the results,
In the figure, a coordinate conversion formula in which the measured coordinates at the points marked with a circle and the NC coordinates best match was obtained by using the least squares method, and all the measured coordinates were converted into values in the NC coordinate system accordingly.

Here, FIG. 18A shows the average error of the three-dimensional coordinate measurement, and FIG. 18B shows the standard deviation of the three-dimensional coordinate measurement. From this result, this measurement system
It has been confirmed that xyz coordinates can be measured with an error of ± 0.3 mm or less and a standard deviation of 0.2 mm or less in a relatively wide space where xyz is 900 × 400 × 400 mm.

Next, the measurement of the absolute positioning accuracy of the 6-DOF articulated robot will be described. Here, the result of actually measuring the absolute positioning accuracy of the hand tip of a 6-DOF articulated robot will be described. The transmitter was fixed to the hand of the 6-DOF articulated robot shown in FIG. 19, the robot was positioned at the grid point coordinates of 36 points as shown in FIG. 20, and the position was measured by this measuring system. The results are shown in Fig. 21.

From this result, the positioning accuracy of the x coordinate at the 34th to 36th positioning points is 1 mm or more, which is considerably poor. However, this is because the experimental condition of the _4th receiver R ₄ is bad, It seems that the transmitter R ₄ picked up the diffracted sound because the transmitter was hidden behind the shadow of the wrist of the robot. Except that there seems to be a problem with these measurement systems, 6
The absolute positioning accuracy of a multi-degree-of-freedom robot is 600
Approx. ± 0.7m in a space of × 400 × 200mm square
It was within m.

As described above, in particular, the three-dimensional position / orientation measuring principle of a robot using three transmitters and four wave receivers was proposed, and a measuring system was constructed based on the principle. According to this measurement system, the sound velocity in the measurement space can be accurately corrected in real time. Also, the accuracy is 1μ
The NC machine tool of m was used as a calibration standard to verify the three-dimensional coordinate measurement accuracy of this measurement system. As a result, xyz is 9
3 in a relatively large space of about 00 x 400 x 400 mm
It was confirmed that the dimensional coordinates were measured with an error of ± 0.3 mm or less for each xyz coordinate and a standard deviation of 0.2 mm or less.

Further, the absolute positioning accuracy of the 6-DOF articulated robot was measured. As a result, it has been found that the absolute positioning accuracy of the 6-DOF articulated robot is within ± 0.7 mm within a space of about 1 m square. As described above, according to the present invention, as a system for evaluating the motion performance of a robot, a simple three-dimensional position / orientation measuring device to which ultrasonic pulse propagation time measurement is applied and a measuring method therefor can be provided. .

The present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0076]

As described in detail above, according to the present invention, the following effects can be achieved. (1) Since the ultrasonic element is inexpensive and the triangulation using the distance is performed, the accuracy is easy to be obtained, that is, the measurement accuracy of the three-dimensional coordinate is determined by the distance measurement accuracy, so that it is high regardless of the size of the measurement space. It is easy to obtain accuracy and is most suitable for evaluation of robot's motion performance.

(2) Since an electric spark is used as a transmitter to measure the propagation time of an ultrasonic pulse for zero-cross point detection and real-time sound velocity correction, signal processing is easy, measurement time is short, and reflection It is less likely to be affected by waves, and the measurement accuracy can be improved. By the way, the average value of the measurement error is within ± 0.1 mm within the measurement range of 1 m, 2 m
Within ± 0.3 mm in the measurement range, and the standard deviation of the measurement error was 0.1 mm or less in the measurement range of 1 m and 0.2 mm or less in the measurement range of 2 m.

(3) The angle of elevation and the turning angle are controlled so that the wave-receiving surface always faces the front of the transmitter by using the wave-receiver having a sharp directivity, so that the coordinates can be measured with high accuracy. Can be widely used. (4) Three-dimensional position / orientation measurement of a robot using three transmitters and three wave receivers. It is easy to determine the initial coordinate system and the wave receivers can be placed at any position for measurement. Has great flexibility in changing the target.

(5) A three-dimensional position / orientation measuring principle of a robot using three transmitters and four wave receivers was proposed, and a measuring system was constructed based on this. According to this measurement system, the sound velocity in the measurement space can be accurately corrected in real time. (6) Further, the NC machine tool having an accuracy of 1 μm was used as a calibration standard to verify the three-dimensional coordinate measurement accuracy of this measuring system. As a result, this measurement system has xyz of 900 × 4.
It was confirmed that the three-dimensional coordinates in a relatively wide space of about 00 × 400 mm can be measured with an error of ± 0.3 mm or less and a standard deviation of 0.2 mm or less for each xyz coordinate.

(7) Further, the absolute positioning accuracy of the 6-DOF articulated robot was measured. As a result, it has been found that the absolute positioning accuracy of the 6-DOF articulated robot is within ± 0.7 mm within a space of about 1 m square.

[Brief description of drawings]

FIG. 1 is a principle diagram of a measurement system using ultrasonic pulses according to a first embodiment of the present invention.

FIG. 2 is a partially exploded perspective view of a transmitter of a measurement system using ultrasonic pulses according to the first embodiment of the present invention.

FIG. 3 is an electric circuit diagram of a transmitter of a measurement system using ultrasonic pulses according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a receiver of the measurement system using the ultrasonic pulse according to the first embodiment of the present invention.

FIG. 5 is a received pulse waveform diagram of electric spark discharge transmitted from the transmitter of the measurement system using the ultrasonic pulse according to the first embodiment of the present invention.

FIG. 6 is a diagram for explaining the effect of the rangefinder according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of a three-dimensional position / orientation measuring principle of the robot according to the first embodiment of the present invention.

FIG. 8 is a schematic overall configuration diagram of a three-dimensional ultrasonic position / orientation measurement system for a robot using ultrasonic waves according to the first embodiment of the present invention.

FIG. 9 is an explanatory diagram of a method for measuring the distance between the wave receivers according to the first embodiment of the present invention.

FIG. 10 is an explanatory diagram of confirmation of effects of the first embodiment of the present invention.

FIG. 11 is a diagram showing a result of angle measurement by confirming effects of the first embodiment of the present invention.

FIG. 12 is a diagram showing a result of position measurement by confirming effects of the first embodiment of the present invention.

FIG. 13 is a principle diagram of a measurement system using ultrasonic pulses according to a second embodiment of the present invention.

FIG. 14 is an explanatory diagram of a three-dimensional position / orientation measurement principle of the robot according to the second embodiment of the present invention.

FIG. 15 is a block diagram of a robot three-dimensional position / orientation measuring system according to a second embodiment of the present invention.

FIG. 16 is an explanatory diagram of a method for measuring the distance between the wave receivers according to the second embodiment of the present invention.

FIG. 17 is a diagram showing an arrangement of a transmitter and a wave receiver for confirming the effect of the second embodiment of the present invention.

FIG. 18 is an explanatory diagram for confirming the effect of NC coordinate measurement according to the second embodiment of the present invention.

FIG. 19 is a perspective view of a 6-degree-of-freedom articulated robot that is a target for measuring absolute positioning accuracy according to the second embodiment of the present invention.

FIG. 20 is a diagram showing the arrangement of transmitters and receivers for confirming the effects of the second embodiment of the present invention.

FIG. 21 is an explanatory diagram for confirming the effect of absolute positioning accuracy measurement of a 6-DOF articulated robot according to the second embodiment of the present invention.

[Explanation of symbols]

1,45 Robot 2,46 Hand 10, T ₁ , T ₂ , T ₃ , 60 Ultrasonic transmitter R ₁ , R ₂ , R ₃ , R ₄ , 64 Wave receiver 11 Stand 11a Support 12 V groove 13 Discharge Needle 14 Holder 15 Screw 21 Power supply 22 Condenser 23 FET 24 Ignition coil 25 Gap 31 Condenser microphone 33, 35 Support shaft 34 Support plate 41 Transmission time detection circuit 42 A / D converter 43 Sound velocity monitoring unit 44, 50, 70 Processing unit 52 High-precision timer 53 Electric spark timing control board 54 Sound velocity calculation board 55 4-channel arrival time measurement board 56,74 Parallel interface and interrupt 51,71 Expansion unit 58 Electric spark power supply 59 Ignition circuit 57 Emission time detector 61,63 Amplifier 62 sound speed monitoring unit 72 Counter 73 D / A converter 75 motor signal distribution circuit 76 a motor drive circuit 77 DC servomotors

Claims (20)

[Claims] 1. An ultrasonic three-dimensional position / orientation measuring apparatus for a robot, comprising: (a) an ultrasonic transmitter for generating ultrasonic pulses using three electric sparks attached to a robot hand; ) Three wave receivers fixed in position to receive the ultrasonic pulse from the ultrasonic transmitter,
(C) A three-dimensional position of the robot by means of ultrasonic waves, characterized by comprising a measuring means for measuring the three-dimensional position and orientation of the robot by triangulation using the distance obtained by measuring the propagation time of the ultrasonic pulse. Attitude measuring device. 2. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 1, wherein the wave receiver is a condenser microphone. 3. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 1 or 2, further comprising a device for adjusting a depression angle and a turning angle of the wave receiver. 4. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 1, further comprising a transmission time detection circuit for detecting a transmission time of the ultrasonic transmitter. 5. An A / D converter for converting an analog signal received from the wave receiver into a digital signal, the transmission time detection circuit connected to the A / D converter, and the A / D converter.
The robot ultrasonic three-dimensional position / orientation measuring apparatus according to claim 4, further comprising an arithmetic processing unit connected to the / D converter. 6. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 5, further comprising a sound velocity monitoring unit connected to the arithmetic processing unit. 7. A method of measuring a three-dimensional position and orientation of a robot using ultrasonic waves, comprising: (a) installing an ultrasonic wave transmitter for emitting ultrasonic pulses using three electric sparks in a hand of the robot; The robot receives the ultrasonic pulse from the ultrasonic transmitter by three receivers fixed at predetermined positions, (c) measures the propagation time of the ultrasonic pulse, and triangulates the distance to make the robot 3D position / orientation measurement method of a robot by ultrasonic wave, which is characterized by performing 3D position / orientation measurement. 8. The ultrasonic receiver detects the transmission time of the ultrasonic transmitter, and the receiver detects a first zero-cross point after the amplitude of the pulse wave due to the electric spark exceeds a threshold value, and based on this detection. The method for measuring a three-dimensional position / orientation of a robot using ultrasonic waves according to claim 7, characterized in that the propagation time of ultrasonic pulses is measured. 9. The method for measuring a three-dimensional position / orientation of a robot by ultrasonic waves according to claim 7, wherein the sound velocity correction is performed in the vicinity of the measurement position. 10. The three-dimensional position / orientation of the robot by ultrasonic waves according to claim 7, wherein the receiver is used to measure the distance between the receivers and calibrate the initial coordinate system. Measuring method. 11. A three-dimensional position of a robot by ultrasonic waves.
In the attitude measuring device, (a) an ultrasonic transmitter that generates ultrasonic pulses using three electric sparks attached to the hand of the robot; and (b) a predetermined ultrasonic pulse that receives the ultrasonic pulses from the ultrasonic transmitters. By measuring the four wave receivers fixed at the positions and (c) the ultrasonic pulse propagation time measurement, four variables of the X, Y, Z coordinates of the ultrasonic transmitter and the sound velocity in the measurement space are calculated, and the distance is calculated. By triangulation using
A three-dimensional position / orientation measuring apparatus for a robot using ultrasonic waves, comprising a measuring means for measuring the three-dimensional position / orientation of the robot. 12. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 11, wherein the wave receiver is a condenser microphone. 13. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 11 or 12, further comprising a device for adjusting a depression angle and a turning angle of the wave receiver. 14. An electric spark timing control board for generating electric sparks from the ultrasonic wave transmitter, and reading of a transmission time from the transmitter, and arrival of an ultrasonic pulse based on a received signal from the wave receiver. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 11, comprising a four-channel arrival time measuring board for obtaining time, and an arithmetic processing unit connected to these boards. 15. The ultrasonic three-dimensional position / orientation measuring apparatus for a robot according to claim 14, further comprising a sound velocity monitoring unit connected to the arithmetic processing unit. 16. A three-dimensional position of a robot by ultrasonic waves
In the posture measuring method, (a) an ultrasonic transmitter that emits ultrasonic pulses using three electric sparks is installed in a robot hand, and (b) the ultrasonic pulse from the ultrasonic transmitter is placed at a predetermined position. Receiving with four fixed receivers, (c) measuring the propagation time of the ultrasonic pulse, and calculating four variables of the X, Y, Z coordinates of the ultrasonic transmitter and the sound velocity in the measurement space. A method of measuring a three-dimensional position / orientation of a robot by ultrasonic waves, which is configured to measure a three-dimensional position / orientation of the robot by triangulation using a distance. 17. The ultrasonic receiver detects a transmission time of the ultrasonic transmitter, and the receiver detects a first zero-cross point after the amplitude of the pulse wave due to the electric spark exceeds a threshold value, and based on this detection. 17. The ultrasonic robot 3 according to claim 16, wherein the propagation time of the ultrasonic pulse is measured.
Dimensional position / orientation measurement method. 18. Compensation of sound velocity without using a sound velocity monitoring unit by estimating and calculating sound velocity in a measurement space from propagation times of ultrasonic pulses from the ultrasonic transmitter to the four receivers. The method for measuring a three-dimensional position / orientation of a robot by ultrasonic waves according to claim 16, wherein 19. The three-dimensional position / orientation of an ultrasonic robot according to claim 16, wherein the wave receiver is used to measure the distance between the wave receivers and calibrate the initial coordinate system. Measuring method. 20. The ultrasonic three-dimensional position / orientation measuring method for a robot according to claim 19, wherein a sound velocity monitoring unit is used in the calibration of the initial coordinate system.