JP4336829B2 - Bridge inspection equipment - Google Patents

Description

  The present invention relates to a bridge inspection facility for inspecting the back surface of a bridge such as a viaduct.

  Bridges such as viaducts become obsolete or damaged due to long-term service. If damage occurs to the bridge, safety may be reduced and serious accidents may occur. Therefore, it is important to perform maintenance and management by regularly inspecting the bridge. However, steel frames and the like are mixed on the back side of the bridge, and the gap is narrow to prevent people from entering, and since it is high, it is extremely difficult to perform direct inspection by people. As a bridge inspection facility for inspecting a bridge without human intervention, Patent Document 1 discloses an inspection by running a patrol robot 3 on a rail 2 provided under the bridge 1 as shown in FIG. 10 of this specification. Inspection facilities to be disclosed are disclosed. The patrol robot 3 includes a camera 4, and is operated by a wireless controller 5 to transmit a bridge back surface image taken by the camera 4 from the antenna 6. The wireless controller 5 can inspect the bridge 1 by receiving the transmitted signal from the antenna 51 and displaying an image or the like on the monitoring television 7.

However, since structural members such as steel frames are intricately confined in a narrow space on the back side of the bridge 1, it is a great obstacle to radio wave transmission. In order to overcome this interference and transmit and receive signals over long distances, powerful radio waves are required. However, unnecessary radio waves are radiated to other equipment, and are subject to regulations of the Radio Law. I have to. Therefore, in the past, it was very difficult to inspect a bridge by transmitting a communication signal over a relatively long distance of about 400 m without violating the Radio Law.
JP-A-8-128015 (FIG. 1)

  The present invention solves the above-described conventional problems, and can transmit the inspection results reliably over a long distance by weak radio waves that do not conflict with the Radio Law and without being obstructed by the structural members. It was made to provide inspection facilities.

The present invention, which has been made to solve the above problems, includes a rail laid under a bridge, a patrol robot having a digital wireless device that travels on the rail and inspects the bridge, and operates the patrol robot. In a bridge inspection facility comprising a robot controller that receives the inspection results, a tightly coupled cable that leaks weak radio waves is laid along the rails, and the patrol robot is an antenna that is in close contact with the tightly coupled cable. In addition to providing a coupler to transmit and receive communication signals between the patrol robot and the robot controller via a tightly coupled cable ,
By forming a concave groove portion wider than the diameter of the tightly coupled cable on the rail surface and supporting the tightly coupled cable on the support member provided in the concave groove portion, a space is secured between the tightly coupled cable and the rail, It is characterized in that a tightly coupled cable is laid with a low protrusion height from the rail surface.

  In addition, the digital wireless device of the patrol robot is equipped with a QPSK frequency variable local oscillator and the transmission / reception frequency of the transmission line can be switched to f01 or f02 by a switch. Preferably, the robot controller is provided with an FSK modulator, the patrol robot digital radio device is provided with an FSK demodulator, and the robot controller transmits the communication frequency to the patrol robot via the FSK control signal. It is desirable to perform the switching instruction at the same time and simultaneously perform switching of the communication frequency of the robot control device by the built-in CPU.

  The bridge inspection facility of the present invention includes a rail laid under the bridge, a patrol robot that travels on the rail to inspect the bridge, and a robot control device that operates the patrol robot and receives the inspection result. In this bridge inspection facility, a tightly coupled cable that leaks weak radio waves is laid along the rail, and the patrol robot is provided with an antenna that is in close contact with the tightly coupled cable. Communication signals can be reliably transmitted and received via the tightly coupled cables. In addition, since the concave groove portion wider than the diameter of the tightly coupled cable is formed on the rail surface, and the tightly coupled cable is supported by the support member provided in the concave groove portion, it is necessary between the tightly coupled cable and the rail. In addition to securing the space, it is possible to secure the space between the bridge structure member and the projecting height from the rail surface.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a bridge inspection facility according to the present invention, in which a rail 2 is laid under a bridge 1 and a tightly coupled cable 8 for leaking weak radio waves is juxtaposed on the rail 2. . A patrol robot (mobile station) 3 equipped with a camera 4 travels on the rail 2, and an antenna 6 called a coupler is disposed on the back side of the patrol robot 3 at a close distance of the tightly coupled cable 8. The video modulator 41 and the camera 4 are connected to the antenna 6. Furthermore, a duplexer 42, a wireless modem 45, and a microcomputer 46 are connected to another antenna 6 in this order. The tightly coupled cable 8 includes a power supply 81 at one end and a terminator 82 at the other end. The power supply 81 is connected to the robot control device (fixed station) 9. The robot controller 9 includes a host computer 91, a wireless modem 92, duplexers 93 and 93a, a video demodulator 94, and a monitor screen 95 that are appropriately connected.

  The patrol robot 3 transmits and receives communication signals to and from the robot controller 9 via the tightly coupled cable 8. That is, in response to a command from the host computer 9 such as traveling and camera angle tilt / pan adjustment, the back side of the bridge 1 is inspected, and the inspection result of the camera 4 is modulated by the video modulator 41 and transmitted to the robot controller 9. To do. The robot controller 9 displays an image on the monitor screen 95 and stores necessary items such as an image, an inspection position, and an inspection date and time for data analysis. The bridge 1 can be inspected by running the patrol robot 3 on the rail 2 provided in the lower part of the bridge 1 by the bridge inspection facility having the above configuration.

  The patrol robot 3 is provided with a microphone 44 via an audio modulator 43. Corresponding to this, a voice demodulator 96 and a speaker 97 are sequentially connected to the duplexer 93a in the robot controller 9. Therefore, when there are workers on the site, the situation of the site can be transmitted to the fixed station side.

  The tightly-coupled cable 8 has a structure as shown in FIG. 2, and is formed by pairing two core wires 83 covered with PE (polyethylene) coating 83 a and accommodating them together with interposition wires 84 in a PE sheath 85. Therefore, it is reinforced by the suspension line 86. The portion of the PE sheath 85 in which the core wire is embedded is formed in a T-shape to facilitate clamping by the support member 23 described later. Since the tightly coupled cable 8 is a balanced cable, the electromagnetic field of the transmission mode of the cable is distributed around the cable. Therefore, the transmission characteristics are affected by the presence of conductive materials such as metal (rails, bridge structural members, etc.) It is affected by deterioration.

  Therefore, the tightly coupled cable 8 is laid inside the rail 2 by forming a groove 21 as shown in FIG. That is, a concave groove portion 21 having a width sufficiently wider than the diameter of the tightly coupled cable 8 is formed along the longitudinal direction on the upper surface of the rectangular tubular rail 2 made of aluminum or the like, and a cable supporting support is provided on the bottom surface 22 of the concave groove portion 21. A member (hanger) 23 is erected. The support member 23 has a cable clamping portion 25 at the top of the base 24 and a bolt 26 at the bottom. Then, bolts 26 are inserted into mounting holes provided in the bottom surface 22 of the recessed groove portion 21 and are fixed by a nut 28 at a required interval (for example, 1 m interval). By supporting the tightly coupled cable 8 on the clamping portion 25 of the support member 23, a necessary space can be secured between the tightly coupled cable 8 and the rail 2. Moreover, since the protrusion height from the rail 2 upper surface can be made low, the space | interval with a bridge structure member can be widened. Therefore, the gap between the peripheral metal members can be increased and the deterioration of the transmission characteristics can be suppressed to a low level.

  On the other hand, the patrol robot 3 can be as shown in FIGS. 4 to 7, and the camera unit 31, the power supply unit 32, and the control unit 33 are mounted on the chassis 30 of the patrol robot 3. Inside the chassis 30, as shown in FIG. 6, an antenna 6 called a coupler is provided downward. Since the antenna 6 is disposed at a very close distance of about 10 mm from the tightly coupled cable 8, it is possible to detect weak radio waves leaking from the tightly coupled cable 8. On the lower side of the chassis 30, four traveling wheels 34 that are in contact with the upper surface of the rail 2 and four wheels 35 that are in contact with the side surfaces of the rail 2 are provided on the front, rear, left, and right sides of the chassis 30.

  The power supply unit 32 is provided with a power supply substrate 320, on which four camera angle control and travel batteries 321 and a microphone 44 are disposed. In addition, the camera unit 31 is provided with the inspection camera 4 and the spotlight 312, and the battery 321 is used as a power source to rotate in the tilt direction by the shaft 313 and in the pan direction by the shaft 314 by a motor, pulley, or the like. Is done.

  The controller 33 is provided with a driver 332 connected to the robot control board 331. The driver 332 includes a DC motor driver 333 for traveling, a DC motor driver 334 for tilt control, and a DC for pan control. Since the motor driver 335 is built in, the patrol robot 3 can be run and the posture of the camera 4 can be adjusted. A power on / off switch 336 is provided above the driver 332. Obstacle sensors 36 are arranged in front of and behind the chassis 30 to stop the traveling of the patrol robot 3 when a traveling obstacle is detected. Further, the disconnection and short circuit of the tightly coupled cable 8 can be detected by the display by the RED 337 of the accessory parts such as the power feeder 81 and the terminator 82.

  Details of the mounting structure of the antenna 6 are shown in FIGS. 8 and 9. The antenna 6 is fixed to the lower surface of the chassis 30 with screws. As described above, since the antenna 6 is disposed at a very close distance to the tightly coupled cable 8, it is possible to detect weak radio waves leaking from the tightly coupled cable 8. Therefore, it is possible to inspect the bridge 1 over a relatively long distance of about 400 m in a narrow space where the structural members of the bridge 1 are complicated without conflicting with the Radio Law. Since the tightly coupled cable 8 and the antenna 6 are not in contact with each other, there is no worn portion and maintenance is easy.

  As described above, the patrol robot 3 has the camera 4 that can freely rotate up and down, right and left, and travels on the rail 2, so that there is no blind spot around the floor board of the bridge 1 that is the most important inspection point. Inspection can be easily performed. And since the inspection result of the patrol robot 3 can be taken into the robot control device 9, the inspection result can be accumulated and the secular change of the important part can be surely grasped. Furthermore, since the patrol robot 3 is composed of the chassis 30 and the camera unit 31 and the control unit 33 installed on the chassis 30, they can be dismantled and placed in the trunk and easily transported by one adult. Can be quickly assembled, operated and removed.

  Further, the patrol robot 3 according to the present invention may be configured as shown in FIG. Here, 2A is a wireless device that exchanges signals with the robot controller 9, 3A is an MPEG encoder, 10A is a controller unit that controls video shooting, sound collection, running, and the like, and 13A is a running motor. The CPU 11A processes a control signal sent from the robot control device 9 side, operates the camera 4, the illumination controller 7A, and the microphone 44, and inspects the controller unit 10A and travels to the robot drive control device 9A. Control and give instructions to the radio unit 2A. The video information captured from the camera 4 is sent to the MPEG encoder 3A as a digital video signal, compressed, and then sent to the radio unit 2A. The signal processed by the wireless unit 2A is transmitted to the robot controller 9 via the antenna 6 and the tightly coupled cable 8.

  FIG. 12 is a diagram showing a configuration around the radio unit 2A, in which 71 is a Reed-Solomon error correction encoder, 72 is a preamble generator, 73 is a randomizer, 74 is a modular adder, and 75 is a differential encoder for QPSK modulation. It is. A signal sent from the robot controller 9 is sent from the FSK modem 34A to the controller unit 10A and the robot drive controller 9A to operate the camera 4. The video inspected by the camera 4 is compressed by an MPEG encoder 3A, and a bit stream (DATA) of framed data, a clock signal (CLK) synchronized with the data, and a transmission enable (TX ENABLE) 3 for capturing frame data. Various types of signals are sent from the MPEG encoder 3A to the wireless unit 2A. In the radio unit 2A, a preamble signal for bit synchronization and frame synchronization on the receiving side is added to the head of this frame signal by the preamble generator 72, and error correction on the transmission path is performed at the end of the frame signal. A Reed-Solomon error correction code is added by the correction encoder 71. The Ramanizer 73 randomizes the data by the modular adder 74 in order to facilitate bit synchronization due to the same bit string continuing. The differential encoder 75 performs differential encoding of the data bit string and conversion into an in-phase signal and a quadrature signal for QPSK modulation. The roll-off filter 76 has a roll-off characteristic for preventing spread of spectrum and preventing interference between signals. The data string is converted into a QPSK signal by the quadrature modulator 77, converted to a predetermined frequency by the upconverter 80, amplified by the amplifier 82A, and transmitted from the antenna 6. The transmitted signal is QPSK demodulated by the video demodulator 94 on the robot controller 9 side. Reference numeral 78 denotes an interface circuit that operates the wireless unit 2A according to a command from the CPU 11A, and 81A denotes a local oscillator of the upconverter 80.

FIG. 13 is a digital signal processing configuration diagram for demodulating a digitized video signal and audio signal by a robot controller (controller). The QPSK digital modulation signal transmitted and input to the DQPSK demodulator 87a is demodulated into a data bit string by the DQPSK demodulator 87a. Since this signal is a framed signal, the preamble is removed by the preamble processor 88a, and the signal randomized by the derandomizer 89a is returned to the original signal. Thereafter, error correction for each frame is performed by an RS (Reed Solomon) error corrector 90a. The filter 91a eliminates intersymbol interference by a band limiting FIR filter, and valid data for each frame is output from a FIFO (First In First Out) 92a in synchronization with an external clock. Reference numeral 93b denotes a timing circuit for performing carrier wave reproduction and synchronous reproduction for demodulating data from a QPSK modulated signal. Reference numeral 94a denotes an interface circuit for causing the DQPSK demodulator 87a to timing circuit 93a to perform functional operations under the control of the CPU 95a. Usually, a PSI or I ² C bus is used.

  FIG. 14 shows the frame configuration of this system. In this frame configuration, the data frame is 188 bytes of video / audio data per frame conforming to ATM UTOPIA, and the total number of bytes of the frame is 204 bytes. In this system, the number of bits of the preamble is set to 10 bytes in order to ensure bit synchronization because the transmission path varies greatly, the RS correction code is 4 bytes, and the guard bits are 2 bytes. The RS correction code can theoretically correct data error of 2 bytes per frame by 4 bytes.

  FIG. 15 is a diagram showing an AGC circuit employed on the robot controller side. In this circuit, the signal input to the hybrid circuit 95a enters the band pass filter 100a and the power amplifier 96a. Since the power amplifier 96a is inputted to the output side of the amplifier 96a at a level much lower than the output signal, it is not affected by this signal. On the other hand, the band pass filter 100a passes only the QPSK signal fp and the information signal fi from the robot, and attenuates the audio signal fc from the power amplifier 96a. The band-pass filter 100a employs a parallel-series band-pass filter, so that only the signal fc is sharply attenuated and, together with the isolation of the hybrid circuit 95a (isolation of 20 to 25 dB), an effect of preventing interference due to wraparound is obtained. is there. Further, since the FSK-modulated information signal from the robot, which is the desired signal, and the QPSK-modulated signal are mutually interrelated signals and are not independent, the frequencies fp and fi are set within the 20 MHz to 50 MHz band. Set.

  As shown in FIG. 22, in the frequency characteristic of the signal that has passed through the tightly coupled cable and the coupler, the frequencies fp and fi fluctuate at substantially the same level. Is provided. When AGC is applied at this level, the 1st AGC amplifier 101a is entered at the same level, so distortion due to the level of two waves is minimized. Also, an AGC amplifier with a wide dynamic range is required in order to handle an input signal level with extremely large fluctuations such as tightly coupled cable transmission. To cope with this, the AGC circuit has a two-stage configuration. When the signal level is low, the 2nd AGC amplifier 103a attenuates quickly so as not to deteriorate the S / N, and when the input is strong, the influence of the third-order distortion due to the second wave is reduced. Therefore, the delay circuit 104a in which the 1st AGC 101a operates is employed. Reference numeral 102a denotes a low noise amplifier and 105a denotes a duplexer.

FIG. 16 shows the configuration of a conventional duplexer for comparison with the embodiment of the present invention. In the figure, the low-pass filter 106a extracts fp and fi, and the fp and fi are amplified by the low noise amplifier 98a and output. Reference numeral 107a denotes a high-pass filter, which outputs fc amplified by an output power amplifier 96a.
FIG. 17 shows the frequency characteristics of the low-pass filter 106a. Although fp and fi pass, if the frequency is not sufficiently separated in the vicinity of fc in the stop band due to the reflection of the low-pass filter 106a, the attenuation characteristic is deteriorated. FIG. 18 shows the frequency characteristics of the high-pass filter 107a. The attenuation characteristics deteriorate near fi and fp.
FIG. 19 is a diagram showing the configuration of the duplexer according to the present invention including the low-pass filter 108a and the high-pass filter 109a. As shown in FIG. 20, the high-frequency characteristics of the hybrid circuit 95a The bounce in the attenuation region can be reduced by the isolation characteristic, and fi and fp can be attenuated by the high-pass filter 109a as shown in FIG.

  FIG. 23 shows the frequency characteristics in the VHF band in which the bridge inspection robot, the radio signal transmission line (tightly coupled cable) on the controller side and the coupler are combined, and FIG. 24 shows the phase characteristics thereof. The transmission line performs amplitude / phase synthesis in the coupler, but the amplitude / phase change point at a specific frequency interval depends on the arrangement position of the coupling loop in the coupler, the synthesis method, and the twisted pair wire of the tightly coupled cable. Appears. In an actual measurement example, a twist pitch of about 80 mm and an arrangement between coupler loops of about 80 mm appear at a frequency interval of 16 MHz to 20 MHz. Further, this frequency changes depending on the installation condition of the laying cable, mismatch with the coaxial cable drawn out for monitoring, and the like. When a digital video signal having a band of 6 to 10 MHz is transmitted through a transmission line having this characteristic, a transmission error occurs at a change point in amplitude or phase. In particular, when QPSK modulation is used, an error occurs when the phase changes by 45 ° or more. Therefore, the frequency must be selected so that the transmission radio frequency band does not enter the amplitude / phase change point. Even if the frequency is optimally set, if the environmental conditions change, the frequency change point changes, so that the frequency needs to be switched. This switching method will be described below.

In FIG. 23, when the transmission frequency is selected as f01 and f02, this change point can be avoided by selecting the relationship between f01 and f02 as follows. That is,
f02 = f01 + △ fs / 2
Here, Δfs is a frequency interval at which a frequency change point appears.
FIG. 25 shows a radio configuration on the patrol robot side and the robot control device (controller) side. 109a is a QPSK modulator, 80a is an up-converter, 110a is a variable frequency local oscillator of f01 and f02, 111a is a band-pass filter having a band through which both f01 and f02 can pass, and 82a is an output power amplifier. . The transmission frequency is switched on the patrol robot side by the switch SW.

  As a method of changing the transmission frequency with the robot-side radio, the frequency of the variable frequency local oscillator 110a is switched between f01 and f02 by the switch SW. Both f01 and f02 pass through the band pass filter 111a, and an RF signal is transmitted from the power amplifier 82a through a tightly coupled cable. In the controller-side radio, the RF signal is received by the transmission / reception separating hybrid 37a and then converted into an IF signal through the low noise amplifier 38a and the down converter 42a. After a part of this signal is taken out by the distributor 112a, the frequency is discriminated by the frequency detector 113a, and the frequency is automatically switched by the frequency variable local oscillator 114a. In this way, switching work can be performed by switching only the transmission frequency on the robot side, so that forgetting frequency switching on the controller side can be prevented. The frequency to be switched is not limited to two of f01 and f02, and may be a number of frequencies.

  FIG. 26 shows a configuration of a radio that employs a method of arbitrarily switching the frequency from the controller-side radio apparatus using the control FSK modulator. Reference numeral 33a denotes a CPU, 34a denotes an FSK demodulator, and 35a denotes a transmission / reception separation hybrid. In the controller-side wireless device, 110a is a synthesizer type local oscillator, 85a is a CPU, and 68a is an FSK modulator. In these wireless devices, the controller 85 switches the IF signal frequency of the down converter 42a by the local oscillator 110a by the CPU 85a, and transmits the frequency setting information to the robot side by the FSK modulator 68a. On the other hand, on the robot side, the frequency of the synthesizer type local oscillator 115a is switched by this control signal. By doing so, there is an advantage that the frequency can be switched immediately even during operation of the robot. The frequency to be switched may be any frequency as long as it is within the reception band regardless of f01 and f02.

  As described above, the video imaged by the camera 4 is used as a digital signal, and this digital video signal is subjected to QPSK modulation which is digital radio modulation, so that a sufficient S / N ratio (signal-to-noise ratio) can be obtained. It was possible to extend the communication distance. In addition, it was possible to improve the degradation of the image quality that occurs when the image is reprocessed or when the video is repeatedly reproduced or duplicated. In addition, by optimizing the correction method by the Reed-Solomon error correction encoder 71, the signal delay in the control and video response from the robot controller 9 side can be greatly improved.

As described above, communication signals can be reliably transmitted and received between the patrol robot and the robot controller via the tightly coupled cable.
Therefore, the present invention has a great value that a bridge can be inspected by weak radio waves that do not conflict with the Radio Law.

It is a schematic block diagram of the bridge inspection equipment of this invention. It is a perspective view which shows the structure of a tightly coupled cable. It is a perspective view which shows the attachment state to the rail of a tightly coupled cable. It is a side view which shows the inside of a patrol robot. It is a top view which shows the inside of a patrol robot. It is a front view which shows the patrol robot on a rail. It is sectional drawing in the AA part of FIG. It is a bottom view of a patrol robot. It is a side view which shows the inside of the chassis of a patrol robot. It is a schematic block diagram which shows the conventional bridge inspection equipment. It is an internal block diagram of a patrol robot. It is a block diagram around a wireless device. It is a block diagram of the digital signal processor in a robot control apparatus. It is a figure which shows the frame structure of the digital signal processor of FIG. It is a block diagram of an AGC circuit. It is a block diagram of the conventional splitter. It is a graph which shows the frequency characteristic of the conventional low-pass filter. It is a graph which shows the frequency characteristic of the conventional high pass filter. It is a block diagram of the duplexer which concerns on this invention. It is a graph which shows the frequency characteristic of the low-pass filter which concerns on this invention. It is a graph which shows the frequency characteristic of the high-pass filter which concerns on this invention. It is a graph which shows the frequency characteristic of a tightly coupled cable. It is a graph which shows the frequency characteristic of the signal which passed through the tightly coupled cable and the coupler at the time of long distance transmission. It is a graph which shows the phase characteristic of the signal which passed through the tightly coupled cable and the coupler at the time of long distance transmission. It is a block diagram of the radio | wireless apparatus by the patrol robot side and the robot control apparatus side. It is a block diagram of the radio | wireless apparatus for switching a frequency arbitrarily using a FSK modulator.

Explanation of symbols

2 rail 3 patrol robot
6 Antenna 8 Tightly Coupled Cable 9 Robot Control Device 21 Groove 23 Support Member

Claims (3)

A bridge comprising a rail laid under the bridge, a patrol robot having a digital wireless device that travels on the rail and inspects the bridge, and a robot controller that operates the patrol robot and receives the inspection result In the inspection facility, a tightly coupled cable that leaks weak radio waves is laid along the rail, and the patrol robot is provided with a coupler that is an antenna that is in close contact with the tightly coupled cable. In addition to sending and receiving communication signals via a tightly coupled cable ,
By forming a concave groove portion wider than the diameter of the tightly coupled cable on the rail surface and supporting the tightly coupled cable on the support member provided in the concave groove portion, a space is secured between the tightly coupled cable and the rail, A bridge inspection facility characterized by low-projection height from the rail surface and laying tightly-coupled cables . The digital radio equipment of the patrol robot is equipped with a QPSK variable frequency local oscillator and the transmission / reception frequency of the transmission line can be switched to f01 or f02 by a switch. The bridge inspection facility according to claim 1, which is prevented by means . The robot controller is equipped with an FSK modulator, the patrol robot digital radio device is equipped with an FSK demodulator, and the robot controller instructs the patrol robot to switch the communication frequency through the FSK control signal. The bridge inspection facility according to claim 1 , wherein the frequency switching is simultaneously performed by a CPU having a built-in frequency .

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