Robot for inspecting floorboard of liquid tank

Abstract

To provide a robot for inspecting the floorboard of a liquid tank which accommodates many elements such as a floorboard inspection device, drive system parts for movement, and a device for self-position estimation all in a long and thin housing and which is capable of entering a liquid tank through a narrow space such as an air hole.SOLUTION: The robot includes a floorboard inspection device facing a floor surface, a drive device for moving on the floorboard, a floating device, and a connecting device that connects the drive device, the floating device, and a position measurement device in series. The robot is configured so that the floating device is placed on top and the floorboard inspection device and drive device are placed on the bottom in liquid, and the drive device moves on the floorboard to inspect the floor surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a robot for inspecting the floor boards of liquid tanks, and more specifically to a robot for inspecting the floor boards of liquid tanks that can be operated in an upright position on the floor boards by being carried into a liquid tank containing liquid such as oil through a narrow opening area at the top of the tank without discharging the liquid from the tank, such as during an open inspection of an oil tank. [Background technology]

[0002] Currently, inspections of oil tank floors are carried out using a method known as open inspection, which requires workers to enter the tank after all the oil has been drained, resulting in high costs and the tank being rendered unusable during the inspection period.

[0003] Therefore, in order to solve such problems, for example, the "robot for in-service inspection and cleaning of oil tanks" as described in Non-Patent Document 1, the square robot disclosed in Non-Patent Document 2, and the "internal inspection method for liquid storage tanks" as described in Patent Document 1 have been developed and disclosed.

[0004] Non-patent documents 1 and 2 disclose examples of inserting a robot through a manhole in the roof of a liquid tank for in-service inspection of the oil tank, and patent document 1 also discloses an example of inserting a robot into the stored liquid through a valve at the top of the liquid tank to inspect the bottom wall for corrosion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Publication No. 60-13682 [Non-patent literature]

[0006] [Non-Patent Document 1] Gary Penney: Robot for In-Service Inspection and Cleaning of Oil Tanks, Pressure Technology, Vol. 49, No. 6, pp. 281-286: 2011 [Non-patent document 2] Nortek AS website: “DVL enables navigation accuracy for tank inspection robots in harsh environments,” [online], [Retrieved April 10, 2024], Internet <URL:https: / / www.nortekgroup.com / knowledge-center / userstory / navigation-accuracy-to-tank-inspection-robots> Summary of the Invention [Problem to be solved by the invention]

[0007] The robots disclosed in the above patent documents are all inspection robots that are immersed in the liquid in a liquid tank, but because they are large, they require a large-diameter entry port in the floating roof or the like on the top of the liquid tank.

[0008] However, the floating roofs of Japanese oil tanks and the like that are intended for use in this invention often only have air holes with an inner diameter of about 150 mm.

[0009] Despite the narrow entrance, the robot requires many elements, such as a floorboard inspection device, drive system components for movement, and a device for estimating its own position. However, conventional technology has had the problem of not providing a robot equipped with various devices that can be inserted through such a narrow entrance area.

[0010] Therefore, the present invention aims to provide a robot for inspecting the floor boards of liquid tanks, which combines many elements such as a floor board inspection device, drive system components for movement, and a device for self-position estimation into a long, thin housing, and which is capable of entering a liquid tank through narrow areas such as air holes. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides a floor panel inspection robot for a liquid tank, which comprises a floor panel inspection device facing the floor surface, a drive device for moving on the floor panel, a floating device, and a connecting device that connects the drive device, the floating device, and a position measurement device in series, and is characterized in that it can move on the floor panel using the drive device in the liquid with the floating device on top and the floor panel inspection device and drive device on the bottom, and inspect the floor surface.

[0012] Furthermore, the above problem can be solved even more effectively by the floorboard inspection device being an ultrasonic sensor, or by the drive device being one of a pair of wheels rotated by a drive source such as an electric motor, multiple Mecanum wheels or omniwheels, a screw, or a caterpillar, or by the liquid tank being provided with multiple transmitters or transceivers, and the position measurement device being able to identify the location of the floorboard on which the measurement was performed by receiving or transmitting from the transmitters or transceivers. [Effects of the Invention]

[0013] The floorboard inspection robot according to the present invention comprises a floorboard inspection device, a drive device, a floating body device, and a connecting device that connects these devices and a position measurement device in series, and these are basically configured so that the outer edges of the projection surfaces in the connecting direction of these devices fit within a predetermined area.

[0014] Therefore, with the floorboard inspection robot according to the present invention, the robot can be easily inserted into a liquid tank even through a narrow area such as an air hole provided on the floating roof on the top surface of the liquid tank.

[0015] Furthermore, in the floorboard inspection robot according to the present invention, since each part is connected in series, when using, for example, a directional ultrasonic sensor as a floorboard inspection device, the transducer (probe) is placed on the end face side of the serially connected device.

[0016] Therefore, when placing the transducer on the floor surface to be measured, it is necessary to place the transducer close to the floor surface and vertically facing it within the measurement tolerance range.

[0017] Therefore, in the present invention, the sensor of the floorboard inspection device is arranged facing the end side of the drive device at the end side of the serially configured housing, or adjacent to it, and the action of the floating device connected via the coupling device causes the robot housing to stand up like a tumbler doll, and even though the housing has a long and slender shape, the sensor part of the floorboard inspection device can be made to face the floorboard and can be kept standing mechanically like an inverted pendulum.

[0018] Therefore, according to the present invention, it is possible to provide a robot for inspecting the floor boards of liquid tanks, which has many elements such as a floor board inspection device, drive system components for movement, and a device for self-position estimation all packed into a long, thin housing, and is capable of entering a liquid tank through narrow areas such as air holes. [Brief explanation of the drawings]

[0019] [Figure 1] 1A and 1B are three-dimensional views of a robot according to the present invention, where (A) is a front view, (B) is a side view, and (C) is a top view. [Figure 2] 1 is a top view illustrating the relationship between the outer edge Sf of the projection plane S and a predetermined area A along the direction in which each component of the housing of the robot according to the present invention is serially arranged. [Figure 3] FIG. 2 is a partial perspective view showing the allowable range of measurement accuracy of the floorboard inspection device. [Figure 4] FIG. 1 is a diagram showing the system configuration of an experimental machine according to the present invention. [Figure 5] This is a diagram that shows an example of measuring position by installing multiple transponders in a liquid tank and communicating with an interrogator installed in the robot body. The arc lines in the diagram show the propagation of radio waves. [Figure 6]10A and 10B are diagrams showing test results of an experimental machine according to an example of the present invention, in which (A) is a graph showing the robot chassis moving forward, and (B) is a graph showing the robot chassis moving backward. [Figure 7] 1A and 1B are explanatory diagrams showing the inclination of the transducer when stopped and when moving, where (A) shows the state when stopped and (B) shows the state when moving. DETAILED DESCRIPTION OF THE INVENTION

[0020] The robot for inspecting the floor board of a liquid tank according to the present invention will be described in more detail below with reference to the drawings.

[0021] Note that the drawings referred to below show an overview of the present invention, and some of the detailed proportions and notations of common structures may be emphasized or omitted to facilitate understanding.

[0022] (Overall Overview of the Invention) First, an overview of the present invention will be described. Since the present invention is a robot for inspecting the floor board of a liquid tank, ultimately, the robot inspects the floor board of a liquid tank in a state where liquid is stored, and maps the results.

[0023] Therefore, the robot itself is driven by a drive unit over the floor of the liquid tank while inspecting the floor with a floor inspection device, and an appropriate coordinate system is set on the floor of the liquid tank, and the inspection results are mapped at the position specified by that coordinate system. The position is specified using the results of an inertial measurement unit, which is a position measurement device connected to the control unit, or a GPS (Global Positioning System) receiver, or a DME (Distance Measuring Equipment) device consisting of multiple transceivers, etc., installed on the liquid tank.

[0024] Furthermore, in the present invention, in order to facilitate the insertion of the robot casing (machine body) into the liquid tank, the robot has an elongated casing in which the devices are connected in series.

[0025] The drive unit that forms one end of the connected elongated housings can be equipped with a floorboard inspection device at that end or can be equipped in parallel, and with the drive unit on the bottom, it is designed to maintain an upright posture like a tumbleweed. Even when moving over the floorboards to inspect them, the floorboard inspection device is controlled based on data from an inertial measurement unit and other sources to maintain an upright posture within the effective measurement range of the floorboard inspection device, and a simulation model for this purpose is also taken into consideration.

[0026] (Overall structure of the present invention) Next, the overall structure of the housing that constitutes the robot for inspecting the floor board of a liquid tank according to the present invention will be described.

[0027] The liquid tank floor inspection robot 100 according to the present invention comprises, for example, a floor inspection device 115, a driving device 110, a floating device 150, and a connecting device 130 that connects the driving device 110 and the floating device 150, as illustrated in Figure 1, and further comprises a position measurement device and a control device (not shown), which are basically connected in series.

[0028] The reason why the position measuring device and the control device are not shown here is that they can be arranged in a dispersed manner inside the floating body device 150, etc., as needed.

[0029] Furthermore, as shown in FIG. 2, these devices are configured so that the outer edge of the projection surface S in the connection direction falls within a predetermined area.

[0030] Here, FIG. 1 shows three views of a robot according to the present invention, where (A) is a front view, (B) is a side view, and (C) is a top view.

[0031] The housing of the robot 100 according to the present invention is connected in series and configured in a long, thin line shape in order to make it possible to easily insert the robot according to the present invention into the liquid tank through an opening provided on the top surface of the liquid tank.

[0032] Therefore, for example, as shown in Fig. 2, if the outer edge Sf of the projection surface S in the connection direction formed by the housing of the robot according to the present invention is set to fit within a predetermined area A, and the predetermined area A is set to, for example, the diameter of an opening provided in the top surface of a liquid tank, the housing of the robot according to the present invention can be easily placed into a liquid tank having the opening. Here, Fig. 2 is a top view illustrating the relationship between the outer edge Sf of the projection surface S along the direction in which each component of the housing of the robot according to the present invention is configured in series and the predetermined area A.

[0033] The diameter of the specified area A is approximately 150 mm, for example, assuming an air vent for a petroleum liquid tank used in Japan, and in the case of the experimental machine 100E of the present invention described later, the maximum outer diameter is set to 109 mm.

[0034] In addition, in the present invention, for example, it is possible to provide a floorboard inspection device 115 on the end or side of the drive device 110 side of the elongated housing, and the measuring device provided in the floorboard inspection device 115 is configured to face the floorboard direction under specified conditions.

[0035] Therefore, in order for the elongated housing of the robot according to the present invention to always maintain an upright posture close to perpendicular to the floorboard and for the floorboard inspection device 115 to face the floor surface, it is desirable to increase the effect of buoyancy on the housing and reduce the effect of gravity.

[0036] Therefore, in the present invention, by providing a floating device 150 on the top of the body, the buoyancy force received by the top of the housing is increased, raising the position of the center of buoyancy; by making the parts on the bottom of the housing heavier (in the experimental machine 100E described below, the drive unit 110 accounts for 60% of the weight), the position of the center of gravity of the body is lowered; and by lengthening the connecting device 130 between the floating device 150 of the housing and the drive unit 110, the distance between the center of gravity and the center of buoyancy is increased.

[0037] In other words, this structure places the center of gravity and the center of buoyancy at a distance from each other, so that the center of gravity is located at the bottom of the robot and the center of buoyancy is located at the top of the robot.Even if the robot is tilted, the buoyancy and moment of gravity will act to rotate the robot's posture and allow it to maintain an upright position.

[0038] In other words, the robot according to the present invention has a structure that is most stable when it is in an upright state in which the lines of force of buoyancy and gravity are aligned vertically in the same straight line.

[0039] (Floor plate inspection equipment and drive unit) Next, the floorboard inspection device 115 and the driving device 110 will be described.

[0040] The driving device 110 in the present invention is a device for moving on the floor surface GL of the liquid tank GT, and has the function of interacting with the floor surface GL (or liquid) of the tank to move the robot 100 in accordance with the present invention.

[0041] The drive unit 110 can use a drive source such as an electric motor and a pair of wheels 113, as in the experimental machine 100E described below, but is not limited to this. For example, it is also possible to use multiple Mecanum wheels or omni wheels, one or more screws, or one or more caterpillars combined with a drive source.

[0042] Furthermore, these pair of wheels, etc. may be configured using an appropriate mechanism so that they can be stored and deployed inside or on the side of the housing before and after passing through the opening of the liquid tank, making it easier to pass through narrow openings.

[0043] Each drive source and wheel 113, etc. are controlled by a control device described later, and the rotation speed, direction, timing, etc. of each wheel, etc. are controlled in conjunction with or independently of each other, so that the entire robot 100 according to the present invention can be moved in any direction and at any speed on the floor surface GL.

[0044] Furthermore, the floor panel inspection device 115, which is provided and connected to the drive device 110, is a device for measuring the floor panel of the liquid tank GT. The floor panel inspection device 115 is arranged on the side of the drive device 110 in the examples shown in Figures 1 and 3, for example, but is not limited to this, and can be arranged in accordance with the characteristics of the floor panel inspection device 115, such as by being sandwiched between a pair of wheels 113 of the drive device 110 or by being arranged on the end side thereof.

[0045] Furthermore, the floorboard inspection device 115 can inspect floor thickness using, for example, a directional ultrasonic sensor, but there are no particular restrictions on the inspection items or inspection methods, and other non-destructive inspection devices can also be used as long as they are used for floorboard inspection.

[0046] Therefore, for example, it is possible to use a measuring device that detects flaws on the floorboard surface, senses the degree of corrosion, or a camera that acquires image information, as needed.

[0047] Furthermore, when an ultrasonic sensor or the like is used in the floorboard inspection device 115, as shown in Fig. 3, the transducer (probe) is provided at the distal end of the floorboard inspection device 115, that is, when viewed along the direction in which the devices of the robot casing are connected, in the arrangement area E on one end side opposite the floating body device 150, facing the floor surface GL. Therefore, the allowable range (allowable measurement accuracy range) in which the measurement accuracy of the ultrasonic sensor is meaningful is the range of the distance R from the floor surface GL and the inclination angle ω of the transducer, as shown by the outline RA with dotted and diagonal lines in Fig. 3, and when inspecting the floorboards, the drive of the drive device 110, etc. is controlled by a control device described later so as to satisfy these conditions depending on the configuration of this device.

[0048] (About the coupling device) Next, the coupling device 130 will be described.

[0049] The coupling device 130 in the present invention is a member that couples the driving device 110 of the robot 100 constituting the present invention with the floating body device 150. Therefore, if the portion of the driving device 110 facing the liquid tank GT is defined as the lower side, one end of the coupling device 130 is connected to the lower end of the floating body device 150, and the other end is connected to the upper end of the driving device 110.

[0050] Furthermore, the connecting device 130 is basically rod-shaped, and is placed between the floating body device 150 and the driving device 110, and there are no particular limitations on the structural material or shape as long as it can connect them.

[0051] Therefore, the connecting device is not limited to being rigid, and can be made of a highly flexible material that can bend to a certain extent, as long as it can pass through the opening of the liquid tank and maintain the connection direction. The same applies to the members used to connect the connecting device 130 to the floating body device 150 or the driving device 110.

[0052] Furthermore, as described above, by lengthening the connecting device 130 between the floating device 150 and the drive device 110 of the casing 100, the distance between the center of gravity and the center of buoyancy can be increased, thereby improving the ability of the connected robot casing 100 to stand on the floor board GL and its ability to recover when tilted, so it is desirable that the length be as long as possible within a practical range.

[0053] Furthermore, if necessary, the inside of the coupling device 130 can be configured to accommodate connection wires between the equipment provided inside the floating body device 150 and the equipment provided in the drive device 110.

[0054] (Floating device) Next, the floating device 150 will be described.

[0055] The floating device 150 constituting the robot 100 of the present invention is a member that applies buoyancy to one end of the robot 100, which is made up of the components connected in series that constitute the present invention, and causes the drive unit 110 to stand up with the downward movement.

[0056] Therefore, the floating device 150 is made of a material that is buoyant in the liquid in which the robot 100 of the present invention is used, and its shape is cylindrical and extends solely along the axial direction of the connected components of the robot 100 of the present invention.

[0057] Therefore, there are no particular limitations on the material of the floating device 150, and it may be a cylindrical outer shell filled with buoyancy material made of air, polystyrene foam, or other materials.

[0058] Similarly, there is no restriction on the outer diameter of the floating device 150 as long as it can achieve the function of the floating device 150. For example, taking into consideration that the entire robot 100 moves through the liquid as the drive unit 110 is driven, it is possible to construct a floating device 150 with an elliptical cross section having its major axis perpendicular to the pair of wheels 113 of the drive unit 110.

[0059] Furthermore, it is also possible to incorporate all or part of equipment such as a position measurement device, such as an inertial measurement unit, inside the floating device 150 as necessary.

[0060] (Regarding the control device) Next, the control device will be described.

[0061] The control device (not shown) in the present invention is a device that controls the driving of the driving device 110 that constitutes the present invention 100, controls measurements by the floorboard inspection device 115, and identifies the position coordinates of the machine on the floorboard GL and measures and controls its posture using an inertial measurement unit equipped with an acceleration sensor or the like as a position measurement device.

[0062] For this reason, the control device is equipped with an MPU (Micro Processing Unit) and is capable of CAN (Controller Area Network) communication and I2C (Inter-Integrated Circuit) communication. For example, in the case of an experimental device 100E (described later), the system configuration is such that, as shown in Fig. 4, a motor driver drives the motor using PWM (Pulse Width Modulation) control or the like to drive the drive device 110, and data from the acceleration sensor of the inertial measurement unit and the like is acquired via I2C communication and used for control by the MPU.

[0063] 4, the robot is controlled entirely from a personal computer via USB (Universal Serial Bus) communication from the robot's housing via a wired signal line FC. However, the present invention is not limited to wired connections, and wireless communication or underwater acoustic communication may also be used depending on the characteristics of the liquid in which the robot is used.

[0064] In the configuration example shown in FIG. 4, the entire robot 100 is controlled from a personal computer, but it is also possible to have a program for driving the housing of the robot 100 pre-installed in the MPU, perform the necessary measurements, store the data internally or send it externally, and then have the housing of the robot 100 return to the collection point after these steps are completed.

[0065] The control device is connected to a position measurement device.

[0066] The position measurement device basically measures the position of the robot according to the present invention (more precisely, the position or area of ​​the measurement point of the floorboard inspection device), and it is possible to use, for example, an inertial measurement unit that can also measure the position and orientation of the robot according to the present invention.

[0067] The inertial measurement unit is equipped with a three-axis accelerometer, a three-axis gyro sensor, and in some cases a temperature sensor, and is capable of measuring the position of the robot casing 100 of the present invention on the floor surface GL and the posture of the robot casing 100 itself.

[0068] Furthermore, these control devices and inertial measurement units are provided inside the housing 100 that constitutes the present invention, but there are no particular limitations on their location; for example, they can be provided all together in the center of the floating device 150, or they can be distributed by component and placed in appropriate locations.

[0069] In the above example, the position and orientation of the robot are measured by an inertial measurement unit, but it is also possible to configure the robot to measure position using a global positioning system (GPS) in addition to, or as a part of, the inertial measurement unit. Similarly, a transmitter or transceiver such as an interrogator may be provided on the robot body, and multiple transceivers or transmitters such as transponders may be provided on the liquid tank as shown in Figure 5, and the coordinates of the robot casing 100 on the floor board GL may be identified using a distance measuring device (DME) configured by these.

[0070] Alternatively, the robot body may be equipped with millimeter wave radar or LiDAR (Light Detection and Ranging) to measure its position within the tank.

[0071] Therefore, with the floorboard inspection robot 100 according to the present invention configured as described above, the robot 100 can be easily inserted into the liquid tank GT even through a narrow area such as an air hole provided on the floating roof on the top surface of the liquid tank GT.

[0072] Then, by the action of the floating device 150 connected via the coupling device 130, the robot's casing 100 stands up like a tumbler doll, and although the casing 100 has a long and slender shape, the floorboard inspection device 115 provided on the drive device 110 can mechanically keep it standing upright relative to the floorboard like an inverted pendulum, and the control device can control it to move over the floor surface while maintaining an upright posture, inspect the floor surface GL, and map the inspection results.

[0073] (Testing using experimental aircraft) Next, test results using the experimental machine 100E, which is an example of the present invention, will be described.

[0074] In the test using the experimental model 100E, the robot's tilt was measured when it was moved through water, with water being treated as oil.

[0075] In the attitude measurement experiment, the attitude of the robot moving underwater was measured using a system similar to that shown in Figure 4 in relation to the explanation of the control device above, and an inertial measurement unit (IMU). In the floorboard inspection experiment, we verified whether an ultrasonic sensor could actually measure the thickness of a metal plate submerged in water with high accuracy. The thickness was measured using a Dakota Japan Co., Ltd. ZX-6 series ultrasonic sensor, and the experiment was conducted in an indoor pool with no waves.

[0076] In the experiment to measure the tilt while the experimental model 100E was moving underwater, the tilt obtained from the IMU was measured, and for the measurements using the experimental model 100E, a first-order low-pass filter with a cutoff frequency of 1 Hz was applied to the measured tilt value to remove the effects of noise.

[0077] The graphs shown in Figure 6 show the results, with Figure 6(A) being a graph of the robot casing 100E moving forward and showing the average of three experimental results using the experimental model 100E, and Figure 6(B) being a graph of the robot casing 100E moving backward and showing the average of three experimental results using the experimental model 100E.

[0078] The experimental results of the 100E aircraft showed that the aircraft tilt during forward movement was a maximum of 0.15 rad and an average of 0.75 rad. Although not shown in the figure, the measurement results varied from experiment to experiment, and this was thought to be due to the wiring on the top of the aircraft.

[0079] Next, a plate thickness measurement test was carried out as an example of an inspection using the experimental machine 100E.

[0080] Here, due to the equipment settings, the ultrasonic sensor used in the test with the experimental 100E mentioned above was unable to measure plate thickness when the transducer was separated from the floor plate surface to be measured. Therefore, in this experiment, the transducer of the floor plate inspection device was attached as shown in Figure 7 so that the transducer and the floor plate surface were in contact when the vehicle was stopped, and there was no interference between the transducer and the floor plate surface when moving forward. In addition, to simulate the floor plate environment in which the vehicle would be traveling, several aluminum plates were lined up. As a result, a certain degree of effectiveness was confirmed, although not shown in the figure.

[0081] The above description is merely an example of the configuration of the present invention, and it is possible to adopt other configurations within the scope of the present invention.

[0082] Therefore, for example, the configuration of the drive device 110, the more specific configuration of the measurement device 115, and even the configuration of the floating device 150 can be different as long as the functions required for the present invention are achieved. [Explanation of symbols]

[0083] 100 Floorboard inspection robot 100E Experimental floorboard inspection robot 110 Drive unit 113 Wheels 115 Floorboard inspection device 130 Coupling device 150 Floating Device Int Interrogator tran transponder S Projection plane along the direction of the serially configured components of the robot's casing Sf The outer edge of the projection plane along the direction of the serially configured components of the robot's housing A designated area E Transducer placement area GT Liquid Tank GL Liquid tank floor R is the distance between the end face of the transducer and the floor of the liquid tank ω Effective tilt angle of the transducer FC wired control signal line RA Measurement Accuracy Tolerance

Claims

1. A robot for inspecting floor panels of a liquid tank, The device is comprised of a floorboard inspection device facing the floor surface, a drive device for moving on the floorboard, a floating device, and a connecting device that connects the drive device, the floating device, and a position measurement device in series, and in the liquid, the floating device is placed on top and the floorboard inspection device and the drive device are placed on the bottom, and the device can move on the floorboard by the drive device to inspect the floor surface. A robot for inspecting floor panels of liquid tanks.

2. 2. The robot for inspecting floor panels of a liquid tank according to claim 1, wherein the floor panel inspection device is an ultrasonic sensor.

3. 2. The robot for inspecting floor panels of liquid tanks according to claim 1, wherein the drive device is one of a pair of wheels rotated by a drive source such as an electric motor, a plurality of Mecanum wheels or omni-wheels, a screw, or a caterpillar.

4. 2. The robot for inspecting floor boards of a liquid tank according to claim 1, wherein the liquid tank is provided with a plurality of transmitters or transceivers, and the position measurement device is capable of identifying the location of the floor board on which the measurement was performed by receiving or transmitting from the transmitters or transceivers.

Images