JPS61256270A - Method and circuit for detecting position of robot - Google Patents

Abstract

PURPOSE:To accurately detect the running position of a robot running along the inner or outer surface of piping, by transmitting an ultrasonic wave from the ultrasonic transmitter mounted to a robot through piping to be used as a medium and measuring the attenuation quantity of the ultrasonic wave at a reference point. CONSTITUTION:An ultrasonic wave containing several kinds of frequencies is transmitted from the ultrasonic transmitter 3 mounted to the robot 2 running along the inner surface (or outer surface) of piping 1 to be transmitted through the piping 1 being a medium and received by the ultrasonic receiver 14 mounted to the running start point of the robot 2 of the piping 1. The attenuation ratio of the ultrasonic wave is constant at certain frequency but changes if the piping has an elbow or the components of earth and soil on the way of the piping change. Hereupon, the absolute position of the robot 2 is calculated according to a specific formula by a calculation circuit 5 having an amplifying circuit, a frequency analysis circuit, a signal selection circuit and an operation circuit. By this method, the absolute position of the robot is calculated if the circumfer ential condition of the piping is different and, because the piping is used as the medium of an ultrasonic wave, the use as a wireless robot is enabled.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for detecting the position of a robot, and in particular, a method suitable for detecting the position of a robot when it travels on the outer or inner surface of piping. and its circuit.

[Background of the invention]

To detect the position of a device or robot running on the inner or outer surface of piping, the following steps are required: (1) Integrating the number of rotations of the robot's wheels, <2) Measuring the length of the cable attached to the TFF pot, etc. method is often used. These methods have the advantage of being easy to measure. However, the method of accumulating the number of rotations of the robot's wheels does not accurately measure the robot's position when the wheels are slipping and the robot is not moving, or when the robot is not moving straight.
1. The method of measuring cable length also does not necessarily have small errors because the cable may become loose.

Such conventional methods have a problem in that the longer the distance traveled by the robot, the more errors accumulate. Note that as a position detecting device for a moving object using ultrasonic waves, there is a technique described in Japanese Patent Application Laid-open No. 83076/1983.

[Purpose of the invention]

An object of the present invention is to provide a method for accurately detecting the running position of a robot running on the inner or outer surface of a pipe. Another object of the present invention is to provide a position detection method that allows wireless transmission without using a transmission cable for position detection.

[Summary of the invention]

The present invention uses ultrasonic waves to accurately detect the position of a robot and to transmit the position signal completely wirelessly. The key point of the present invention is to mount an ultrasonic transmitter on the robot, transmit ultrasonic waves from the transmitter to the entire piping medium, and then return to the reference point (the starting point of the robot) to determine the amount of attenuation of the ultrasonic waves. By measuring the distance traveled by the robot, the total position is measured.

In this case, by using a large number of ultrasonic frequencies, the accuracy of position measurement is increased.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a change in amplitude A with respect to distance X when an ultrasonic wave propagates through a steel material. In the figure, when the frequency f, which is a parameter, is high, it indicates that the attenuation is severe. This phenomenon is already well known. The present invention applies all of these phenomena to accurately detect the position of a robot.

FIG. 2 shows an example of a configuration for explaining the ejection method. In the figure, when the robot 2 travels inside the pipe 1, an ultrasonic transmitter 3 emits ultrasonic waves containing several types of frequencies, and the ultrasonic waves are transmitted to the receiver 4 via the pipe 1' and then reflected. is received, and the calculation circuit 5 calculates the robot's digit 1X.

The method for calculating the ix (ix) will be explained below using a mathematical formula. From the relationship shown in FIG. 1, the amplitude A of the ultrasonic wave is expressed as in formula (1).

At(X)=A+*-α(fI)・X...
...(1) Here, A I(x): Ultrasonic amplitude A1° at distance X:
Amplitude α of the emitted wave: Attenuation rate fl of the ultrasonic wave: Frequency X of the ultrasonic wave: Distance subscript i: Number of frequency components Amplitude of the emitted wave A1. For (i-1...m), (
2) There is a relationship as shown in the formula, and if the ultrasonic transmitter 3 is determined, the constant is known in advance. In other words, it is determined by the frequency characteristics of the oscillator.

Ao + = k IAo +---(2) where, An+: frequency f! In the case of piping, the attenuation factor α (fI) in the amplitude equation (1) of the transmitted ultrasonic wave is generally (
3) It can be expressed as a polynomial such as Eq.

α(fI)=Σ CJf+ ・・・・・・・・・
...(8)mO Here, CJ: coefficient coefficient CjIl'! , is a value that determines the amount of attenuation during propagation of ultrasonic waves, and varies depending on the material of the pipe, the surrounding conditions of the pipe, for example, the state of contact with earth and sand, etc. Therefore, it is better to consider it as an unknown quantity.

The position X of the robot is determined from equations (1) to (3). At this time, the unknown quantity is the sum of X, CJ, and AOI (, T
+3), so this number of simultaneous equations is required. In other words, the number m of frequency components may be (J+3>).

Normally, if J = 1 to 2, the attenuation rate α can be approximated, so
It is sufficient that the number m of frequency components is 4 to 5.

When calculating the distance X from equation (1), a point after a certain distance may be used as a new reference point. If this is expressed numerically, it becomes equation (4).

ΔA+(Δx)=ΔAl0−α(f−Δx ・−・(
4) Here, ΔAI=AI(x+Δx)−AI<X)Δ
Ago”lA+o (X+Δx)−Ato(X)ΔX
m (X+Δx) −x The advantage of using the variation ΔA1 shown in equation (4) is that the measurement error can be reduced even when the attenuation rate αCf,) changes rapidly depending on the surrounding conditions of the pipe. This will be explained in detail below.

The attenuation factor α is constant at a frequency f, as shown in FIG. However, if the piping is not a straight pipe but an elbow, and the composition of earth and sand changes suddenly in the middle of the piping, the value of α itself changes.

That is, there is distance dependence of the attenuation rate α. Therefore, each time the robot travels a certain distance (every ΔX interval),
What is necessary is to find the attenuation rate α and the distance 1ffI X .

The attenuation factor α is approximately 1 dB/m in steel pipes, so it is several 1.0
Since the dB amplifier is easy to use, the number 10
Measurements can be made up to a distance of m. The accuracy of the amplifier is 0.1
Since it can be easily done to the extent of d B, the calculation accuracy of the distance @X can be suppressed to within a few tens of mouths, which is a practical cough. An example of an ultrasonic waveform is shown in FIG. This is an example in which the waveform is not necessarily monotonous, but since the present invention is based on the sensitivity range, it is sufficient to take the maximum value A in the figure.

A specific embodiment of the calculation circuit 5 in FIG. 2 is shown in FIG. 4. It is composed of an amplifier circuit 51 for amplifying the received eyebrow sound wave signal A (X), a frequency analysis circuit 52, a signal selection circuit 53, and a calculation circuit @54. The amplifier circuit 51 only needs to have a sensitivity with an amplification factor of 10 dB to compensate for the attenuation of the ultrasonic waves. The frequency analysis circuit 52 determines the frequency spectrum of the received signal, and calculates, for example, equation (5).

(5) The integration time in equation (5) may actually be up to the time when the received signal A(x, t) disappears. In the selection circuit 53, a separately predetermined frequency f+ + f2 +...
...Amplitude AH, At of the received signal corresponding to f,,a.

...A is taken out from the frequency analysis circuit 52. In the arithmetic circuit 54, the amplitude AI, A2H...
A, as well as a constant externally set kl + k2 +・
・・・・・・k.

(a known value that can be uniquely determined by the combination of the probe or transmitter 3 and receiver 4) is used to solve equation (1) to find the position X of the robot.

One embodiment in FIG. 4 shows a case of one set of transmitter 3 and receiver 4. The reason why one set of transmitter and receiver is used is that even if the contact state between the probe and the pipe changes, the constant kl + k2
This is because +...k can maintain an unchanging relationship. A plurality of pairs of transmitters 3 and receivers 4 may be used as long as the contact state can be maintained the same. In the case of such a configuration, the frequency analysis circuit 52 and signal selection circuit 53 in the configuration of FIG. 4 (C) become unnecessary.

Whether there is one transmitter 3 or a plurality of transmitters 3, it is necessary to maintain a good contact state with the pipe 1 in order to receive a stable signal. An example of the configuration of a device for this purpose is shown in FIG. Connect the skirt 32 between the transmitter 3 and the pipe 1 to the transmitter 3.
Install around the area.

Further, in order to appropriately press the transmitter 3 against the pipe 1, a pressing mechanism 33 is provided in the robot 2.

The pressing mechanism 33 may be, for example, a well-known pantograph mechanism or a solenoid mechanism.

FIG. 6 shows an example of the timing from the transmission of ultrasonic waves to the determination of the position X of the robot. Ultrasonic waves are transmitted with a period T. During this time, the receiver 4 receives the ultrasonic wave, and then the frequency analysis circuit 52 calculates the amplitude AII A2H of each frequency component.
・・・・・・Find A, and then find the robot's position
Calculate.

The period T is centered so as to satisfy equation (6).

Otherwise, the size of the received wave and the transmitted wave is 111! l! I can't hold it anymore.

T>L/C・・・・・・・・・(6) Where, T: Period of emitted wave L: Measuring range of robot position C: Propagation speed of ultrasonic wave On the other hand, permissible error of position measurement From the relationship, the period T must be shortened so as to satisfy equation (7).

Tku δx / v ・・・・・・・・・(7)
Here, δX: Position measurement tolerance V: Robot speed The specific period that satisfies equations (6) and (7) is as follows: robot position measurement range L = 100 m, ultrasonic propagation speed C =
6Km/s, position measurement tolerance δx = 10 saws, robot speed 2! If it is b/h, it is approximately 0.2 s, which is a value that can be set realistically. During this time, frequency analysis and calculation of the position f〆 can be fully executed.

In the present invention, it is possible not only to measure the position , wireless scanning of inspection robots is possible. As for the specific timing of signal transmission, for example, the information of two communication signals may be transmitted immediately after the transmission for position measurement shown in FIG. At this time, the transmitter 2 for position measurement may be used, or a separate transmitter for information transmission may be provided.

〔Effect of the invention〕

As explained above, according to the present invention, the robot Since the absolute position of the piping can be measured, when the piping is inspected or repaired by a robot, it is possible to reliably grasp the target location of the contract. Furthermore, since piping is used as a medium for ultrasonic waves, it becomes possible to realize a wireless robot.

The above explanation is limited to the case where the robot moves inside or outside the piping. However, if the position can be detected using ultrasonic waves as in the present invention, it is possible to accurately detect the position of loosening of an object that generates ultrasonic waves (for example, a component inside a beak structure).

[Brief explanation of drawings]

Fig. 1 shows the attenuation characteristics of ultrasonic waves over distance, Fig. 2 shows a specific example of position measurement, Fig. 3 shows an example of the ultrasonic waveform,
FIG. 4 shows an example of position calculation, FIG. 5 shows an example of a mechanism for maintaining contact between the transmitter and the pipe, and FIG. 6 shows an example of timing of position measurement signals. fl...frequency, AI...amplitude of received signal, X...
・Robot position (or distance between transmitter and receiver),
1... Piping, 2... Robot, 3... Transmitter, 4
...Receiver, 5...Calculation circuit, 51...Amplifier,
52... Frequency analysis circuit, 53... Selection circuit, 54
...Arithmetic circuit, 31... Couple material, 32... Skirt, 33... Pressing mechanism.

Claims (1)

[Claims] 1. Using an ultrasonic transmitter attached to a mechanism that travels on the inner or outer surface of a structure such as piping, and an ultrasonic receiver attached to the structure, a plurality of frequency components can be transmitted. A robot position detection method characterized by measuring the position of a traveling mechanism from the amount of attenuation during propagation of ultrasonic waves. 2. The robot according to claim 1, characterized in that the position of the traveling mechanism is measured by adding two frequency components to the number of unknown constants related to attenuation of ultrasonic waves. Location detection method. 3. The method for detecting the position of a robot according to claim 1, characterized in that the measurement is carried out using one ultrasonic transmitter that includes a large number of frequency components. 4. The robot position detection method according to claim 1, characterized in that a plurality of ultrasonic transmitters each containing a single frequency component are used. 5. A separate circuit that consists of an ultrasonic transmitter attached to a mechanism that travels on the inner or outer surface of a structure such as piping and an ultrasonic receiver attached to the structure, and that analyzes the frequency components of the received ultrasonic wave. a circuit that selects the amplitude of a defined frequency component;
A robot position detection circuit comprising a circuit that calculates the position of the traveling mechanism from a simultaneous equation showing the relationship between the amplitude of the frequency component and the amplitude of the transmitted wave. 6. In claim 5, the robot is characterized in that, when a plurality of ultrasonic transmitters each containing a single frequency component are used, the robot is configured only with a circuit that calculates the position of the traveling mechanism. Position detection circuit.