JP3132970B2 - Robot position detection device in metal tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the position of a robot which travels and works in a metal pipe such as a gas pipe under remote control. The present invention relates to a radio-wave radar device that performs the following.

[0002]

2. Description of the Related Art Most gas pipes buried underground have a small diameter so that workers cannot enter. For this reason, in order to search for a gas leak point due to cracks or corrosion after the gas pipe is buried, an exploration robot equipped with a camera is carried into the gas pipe and traveled under remote control . In such an exploration system using a robot, it is necessary to detect the current position of the robot. Conventionally,
The current position of the robot is detected by measuring the feed amount of the cable to the robot in the gas pipe using an encoder, or transmitting the value of the rotary distance meter in the robot to the outside of the pipe via the cable.

[0003]

In the conventional robot position detecting method described above, since slippage exists in a mechanism for feeding a cable to the robot and a rotary distance meter in the robot, an inevitable error occurs in the measured position value. There is a problem that occurs. In addition, especially in the latter method, if a failure occurs in the electric system in the robot and the notification of the current position becomes impossible, the robot goes missing, and it takes much time to collect this from the gas pipe. The problem is that the labor increases. Accordingly, it is an object of the present invention to provide a position detecting device capable of detecting a position of a robot even when a failure occurs in an electric system without a decrease in accuracy due to slip in the mechanism.

For a robot that travels in free space, a radar device using ultrasonic waves, light, or radio waves can be considered as a position detecting device for solving the above problems. However, the gas pipe on which the robot travels includes not only straight pipes but also discontinuous points such as branch points and bend points. Regardless of the location of the bend, the ultrasonic wave or light may not be able to enter there at the branch point, and there is a problem that the ultrasonic wave or light cannot reach the position of the robot beyond the branch point.
Accordingly, it is an object of the present invention to provide a position detecting device that can be applied to a robot traveling in a branched or bent metal pipe.

[0005] In the radio radar, it is necessary to sufficiently consider the relationship between the wavelength of the radiated radio wave and the dimensions of the metal tube. For example, if the wavelength of the radiated radio wave is set to a value several times larger than the size of the metal tube, the radio wave cannot be propagated in the metal tube. Conversely, if the wavelength of the radio wave is made too small compared to the dimensions of the metal tube, not only will the same problem as in the case of light described above occur, but also a large number of propagation modes with different propagation speeds will occur. There is a problem in that a large number of reflected waves with different timings are received from the reflection source, resulting in a decrease in measurement accuracy.

The apparatus for detecting the position of a robot in a metal tube according to the present invention includes transmission / reception means for radiating radio waves into the metal tube and receiving reflected waves thereof. The center frequency of the radio wave radiated into the metal tube is higher than the cutoff frequency of the radio wave propagating in the lowest order waveguide mode in the metal tube, and the radio wave propagating in the next higher order waveguide mode in the metal tube. Is set to a value lower than the cutoff frequency. Further, according to the present invention,
According to the position detecting device of the robot, an FM radar system that emits an FM signal into a metal tube is employed.

[0007]

According to the present invention, the center frequency fo of the radio wave radiated into the metal tube is slightly higher than the cutoff frequency of the radio wave propagating in the lowest waveguide mode in the metal tube, It is set to a value slightly lower than the cutoff frequency of the radio wave propagating in the waveguide mode. For example, if the cylindrical metal tube diameter Dcm, the lowest order TE ₁₁ mode cut-off frequency f of the
c ₁ is fc ₁ = (3 × 10 ¹⁰ ) / (1.706 D) Hz = (17.58 / D) × 10 ⁹ Hz = (17.58 / D) GHz (1) cutoff frequency fc ₂ of the next TM ₀₁ mode is ^{_{fc 2 = (3 × 10 10}} ) / (1.306 D) Hz = (22.97 / D) GHz ····· (2).

Accordingly, the center frequency fo of the FM signal radiated into the metal pipe is fc ₁ <fo <fc ₂ (3) (17.58 / D) GHz <fo <(22.97 / D) GHz ······ (4) Accordingly, only the lowest order TE ₁₁ mode allows the propagation, TM ₀₁ mode, TE ₀₁ mode, a number of higher order modes such as TM ₁₁ mode becomes impossible propagation. As a result, it is possible to avoid the problem that a large number of reflected waves from the robot are received at different timings for various propagation modes having different propagation speeds, and the detection accuracy is reduced. Hereinafter, the present invention will be described in more detail with reference to examples.

[0009]

FIG. 1 is a block diagram showing a configuration of an apparatus for detecting the position of a robot in a metal tube according to an embodiment of the present invention, wherein 1 is an FM signal generator, 2 is a signal distributor, and 3 is a transmitting antenna. Reference numeral 4 denotes a receiving antenna, 5 a mixer, 6 a fast Fourier transform unit, and 7 a CPU.

The FM signal generator 1 generates a function generator that generates a voltage that changes in a triangular waveform with time, and receives a voltage of the triangular wave generated by the function generator at a control terminal and changes the frequency in a triangular waveform. And a voltage-controlled oscillator for generating a signal. A part of the FM signal generated by the FM signal generator 1 is supplied to the transmitting antenna 3 through the signal distributor 2 and radiated into the metal tube M therefrom.

The FM signal radiated from the transmitting antenna 3 into the metal tube M propagates through the metal tube in the lowest order TE ₁₁ mode, and the robot's metal part or the last part existing at an appropriate position in the tube. The light is reflected by a metal reflector mounted on the tail. The reflected wave propagates in the metal tube M in the opposite direction in the lowest order TE ₁₁ mode, and is received by the receiving antenna 4. The reflected wave received by the receiving antenna 4 is supplied to one input terminal of the mixer 5 and mixed with the FM signal supplied to the other terminal through the signal distribution unit 2.

FM supplied to each input terminal of the mixer 5
The signals are shifted in time by the propagation time required for the FM signal radiated from the transmitting antenna 3 to reciprocate with the robot R. For this reason, the mixer 5 generates a beat signal having a frequency proportional to the required propagation time. The frequency of the beat signal is converted into a frequency spectrum by the next-stage fast Fourier transform unit 6 and supplied to the CPU 7.
The CPU 7 analyzes the frequency spectrum of the beat signal supplied from the fast Fourier transform unit 6, calculates the distance from the antennas 3 and 4 to the robot R, and determines the position of the robot R.

The center frequency fo of the FM signal generated by the FM signal generator 1 is the cutoff frequency of the TE ₁₁ mode, which is the lowest waveguide mode propagating in the metal tube M, and the next higher mode. It is set to an intermediate value with the cut-off frequency of _TM01 mode. Thus, to limit the frequency range,
An FM radar system that is sufficient in a narrow fractional band is superior to a pulse radar system that requires a wide fractional band.

[0014]

As described in detail above, the position detecting device for a robot in a metal tube according to the present invention determines the center frequency of the radio wave radiated into the metal tube in each of the lowest order and the next higher order in the metal tube. Since the configuration is such that the cutoff frequency of the waveguide mode is set to an intermediate value, the reflected wave of the lowest mode can be received and the detection accuracy is improved.

Further, according to the present invention, since the FM radar system is employed instead of the pulse radar system, there is an effect that the position of the robot in the metal tube can be detected accurately even at a short distance at relatively low cost. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration for transmitting and receiving a position of a robot in a metal tube according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 FM signal generating circuit 2 Distribution circuit 3 Transmitting antenna 4 Receiving antenna 5 Mixer 6 Fast Fourier transform circuit 7 CPU M Metal tube R Robot

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshimitsu Nozu 6-22-12 Tamadaira, Hino-shi, Tokyo (56) References JP-A-7-4941 (JP, A) JP-A-7-5251 (JP, A) JP-A-5-284019 (JP, A) JP-A-8-105905 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ^7/ 00-7/64 G01S 13 / 00-15/96 F16L 55/18

Claims (1)

(57) [Claims] 1. A robot for detecting the position of a robot running in a metal tube, comprising a transmitting / receiving means for radiating radio waves in the metal tube and receiving a reflected wave in order to detect a position of the robot running under remote control in the metal tube. The apparatus, wherein a center frequency of a radio wave radiated into the metal tube is a cutoff frequency of a radio wave propagating in the lowest waveguide mode in the metal tube and a cutoff frequency of a radio wave propagated in the next higher waveguide mode. is set to an intermediate value of the cutoff frequency, said transmitting and receiving means, the metal pipe and the FM signal generator for generating an FM signal, an FM signal whose FM signal generator is generated whose frequency varies temporally An antenna unit for receiving from the inside of the metal tube an FM signal radiated to the robot and reflected by the metal part of the robot; and mixing the received FM signal with the FM signal generated by the FM signal generation unit to generate a difference frequency. Over a mixing section for bets signal generated, the position detecting apparatus of this from the frequency of the generated beat signal in the mixing section of the metal tube, characterized in that a position detector for detecting the position of said robot robot.