JPH06258020A - Submersible robot - Google Patents

Abstract

PURPOSE:To provide a submersible robot useful in the work for laying a cable in the water or under the bottom of the water or in the maintenance work of pipe line. CONSTITUTION:The submersible robot comprises a probe 6 for detecting magnetic field generated directly or indirectly from an object A, and an optical azimuth meter 7. The azimuth meter 7 comprises a pair of optical fiber gyro arranged such that the axes of rotation detecting coils intersect perpendicularly while directing horizontally. The azimuth meter 7 is not susceptible to the magnetic field at all and determines the azimuth thereof correctly in the detection relying upon the magnetic field thus specifying the detecting point accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater robot which can be used for maintenance of a submarine cable or a submarine pipeline.

[0002]

2. Description of the Related Art Underwater robots that work underwater are preferably equipped with an azimuth meter for recognizing their position. Conventionally used azimuth meters are limited to geomagnetic detection types.

[0003]

Even if the conventional underwater robot is equipped with an azimuth meter, the azimuth meter is of the above-mentioned geomagnetic detection type. Therefore, it is used for maintenance of cables and pipelines installed underwater. It's hard to do.

That is, the geomagnetism detection type azimuth detector detects the direction of weak geomagnetism to know the azimuth. On the other hand, in the vicinity of the cable, a magnetic field is generated by the current flowing through the cable conductor to disturb the earth's magnetism, so that the direction detected by the above direction meter is inevitable.

Further, even in the case of a pipeline or the like in which no current flows, if it is buried in the bottom of the water, it is impossible to search with a camera, and there is a case where the magnetic search method or the like must be relied upon. In this case, a method of flowing a current through the pipeline to generate a magnetic field for exploration, or generating a strong pulsed magnetic field near the pipeline to generate an induced current in the pipeline and detecting the magnetic field generated by the current, etc. The exploration method of

However, with these methods, even if the cable or pipeline can be successfully searched, the direction of the underwater robot cannot be correctly recognized due to the deviation of the detection direction due to the disturbance of the geomagnetic field, and the installation route cannot be accurately grasped. . Therefore, it was not possible to use it for maintenance.

The present invention is intended to provide an underwater robot that solves this problem.

[0008]

In order to solve the above-mentioned problems, the underwater robot of the present invention provides a magnetic field generated directly or indirectly from a cable or pipeline laid in water or buried in the bottom of the water. It has a structure that has both a reliable exploration means and an optical azimuth meter for recognizing its own position.

The optical azimuth meter used here is a combination of two sets of optical fiber gyros in a state in which the rotation detection axes of the rotation detecting optical fiber coils of each gyro are orthogonal to each other and both are oriented in the horizontal direction. Those that are present are preferred.

[0010]

Since it has a magnetic field sensing type exploration means, it is possible to detect even a cable buried in the bottom of the water.

Further, when the magnetic field sensing type exploration means is used, it is necessary for the robot to approach the magnetic field generated in the exploration target to a distance at which it can be sensed, so that the geomagnetic detection type compass is affected by the magnetic field. However, if it is an optical azimuth meter that utilizes the interference of light, it will not be affected by the magnetic field at all, and its own azimuth can be correctly recognized even when it is sufficiently close to the object to be searched.

[0012]

FIG. 1 shows an example of the underwater robot of the present invention.

As shown in FIG. 1, this underwater robot is
A motor-driven traveling mechanism 1, a front monitoring camera 2, a light 3, a traveling meter 4 and the like are provided. The manipulator 5 and an abnormality detection sensor for the object to be searched may be added as necessary.

This underwater robot is equipped with a probe 6 including a magnetic sensor and an optical azimuth meter 7. Signals from the travel meter 4, the exploration device 6, the compass 7 and the image signal of the camera 2 are input to the control unit 8 and sent to the remote control unit on the ship, for example, via the communication cable 9. Further, a command from the remote control unit is sent to each onboard device via the control unit 8 to control the movement of the robot.

The probe 6 may be of the following three types, and any of them may be used.

(1) Detecting the position of the cable by detecting the magnetic field generated around the cable by the current flowing through the cable conductor.

(2) An electric current for detection is passed through the armored iron wire of the cable, the pipeline itself, etc., and the magnetic field generated by this electric current is detected.

(3) A device which emits a pulsed magnetic field from the probe 6 to generate an induced current in the object A to be searched and detects the magnetic field generated by the current.

FIG. 2 shows a specific example of the optical azimuth meter 2
A combination of a set of fiber optic gyros is shown.

An optical fiber gyro utilizing the Sagnac effect generally has a structure as shown in FIG. Reference numeral 10 in the figure denotes an optical fiber coil, which splits the light from the light emitting element 11 by the optical coupler 12 and passes the light through the coil 10 clockwise and counterclockwise. Then, the magnitude of the interference between the clockwise light and the counterclockwise light generated by the rotation of the optical fiber coil 10 is examined, and the angular velocity of rotation is obtained from the magnitude. Although the illustrated optical fiber gyro uses the polarizer 13 in order to remove the influence of the difference in the polarization histories of the clockwise light and the counterclockwise light, it is also possible to remove the influence by using the polarization maintaining fiber. It is considered. Further, in order to have sensitivity, the phase modulator 14
May be used.

The azimuth meter 7 of FIG. 2 uses two sets of such optical fiber gyros, and the optical fiber coils 10 _-1 and 10 _-2 of each gyro are orthogonal to each other and rotation detection of both is detected. The axes are combined so that they both point in the horizontal direction.

In this azimuth meter 7, when the combined coil is rotated once around the vertical axis, the degree of the influence of the rotation of the earth is changed and the output change as shown in FIG. 3 is obtained. Therefore, if the outputs of the two combined gyros are known, the azimuth can be specified without detecting the geomagnetism, and the position of the robot can be accurately grasped by the direction and the amount of movement from the reference point. In this way, the position of the robot can be sequentially grasped, so that the robot can be used for mapping the installation route and detecting trouble points.

[0023]

As described above, the underwater robot of the present invention uses a magnetic field sensing type probe to search for an object buried in the water bottom, and also uses an optical compass. Since it is possible to accurately grasp its own direction without being affected by the magnetic field, it can be used for checking the position of cables and pipelines, detecting trouble points, etc.
This is useful for improving the maintenance and management of this type of laying equipment and for early repair of troubles.

Since the optical fiber gyro has no moving parts as compared with the gas flow type gyro and the mechanical type gyro, it has a long service life, a short start-up time, can be downsized, and has a high degree of freedom in sensitivity design. There are merits, and therefore, it also leads to sophistication, downsizing, reliability improvement of the robot itself.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an underwater robot of the present invention.

FIG. 2 is a diagram showing a combined state of optical fiber coils of an azimuth meter in which two optical fiber gyros are combined.

FIG. 3 is a diagram showing an outline of a general optical fiber gyro.

FIG. 4 is a graph showing an output change due to rotation of an azimuth meter using an optical fiber gyro.

[Explanation of symbols]

 1 traveling mechanism 2 monitoring camera 3 light 4 traveling meter 5 manipulator 6 magnetic field detection type probe 7 optical azimuth meter 8 controller 9 communication cable 10 rotation detection optical fiber coil 11 light emitting element 12 optical coupler 13 polarizer 14 phase Modulator A Object to be searched

Claims (2)

[Claims] 1. A means for exploring a cable or pipeline laid in water or buried in the bottom of the water, relying on a magnetic field generated directly or indirectly from the cable or pipeline, and an optical compass for recognizing its own position. An underwater robot that has both. 2. An azimuth meter comprising two sets of optical fiber gyros combined such that the rotation detection axes of the rotation detecting optical fiber coils of each gyro are orthogonal to each other and both are oriented in the horizontal direction. The underwater robot according to claim 1, which is equipped.