In-pipe mobile robot system

Abstract

The objective is to provide a pipe-in-pipe mobile robot system that can detect artificial muscle bursts more robustly against external disturbances while having the pressure measurement unit located on the control unit side. [Solution] A pipe-moving robot system comprising a robot body equipped with artificial muscles, a gas supply unit connected to the artificial muscles via a flexible tube, and a control unit that controls the operation of the gas supply unit, wherein the robot body moves inside the tube when compressed gas is supplied to the artificial muscles, the pipe-moving robot system comprising a pressure measuring unit provided between the gas supply unit and the tube, and a detection unit that acquires a first pressure measured by the pressure measuring unit at a first timing of the expansion process of the artificial muscles and a second pressure measured by the pressure measuring unit at a second timing of the expansion process of the artificial muscles, and detects whether or not the artificial muscles burst based on the first pressure and the second pressure.

Description

Technical Field

[0001] The present invention relates to an in-pipe mobile robot system.

Background Art

[0002] In-pipe mobile robots configured to move inside winding pipes such as air ducts for air conditioners and various piping installed in office buildings, factories, detached houses and the like are known (see, for example, Patent Document 1). Such in-pipe mobile robots are used for various applications such as inspection and cleaning inside pipes.

[0003] Conventionally, as the in-pipe mobile robot system described above, there is known a system including a robot main body provided with artificial muscles that expand in the radial direction and contract in the axial direction when compressed gas is supplied, a gas supply unit connected to the artificial muscles via a flexible tube, and a control unit that controls the operation of the gas supply unit, wherein the robot main body is configured to move inside the pipe using the artificial muscles as a drive source when compressed gas is supplied from the gas supply unit to the artificial muscles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the pipe-mobilizing robot system described above, if the artificial muscles burst while the robot is moving inside the pipe, there is a risk that the robot will get stuck inside the pipe. In particular, in systems where the robot is propelled forward by expanding and contracting multiple artificial muscles in a pattern to create peristaltic motion, if even one artificial muscle bursts and the robot continues to move forward, the resistance against the pipe will become greater than the propulsion force, potentially causing the robot to get stuck inside the pipe and making it difficult to recover. Therefore, it is necessary to detect artificial muscle bursts as early as possible.

[0006] To reliably detect bursts in artificial muscles, one could consider equipping the robot body with a pressure measuring unit, such as a pressure sensor. This unit would directly monitor the internal pressure of the artificial muscle, and the burst would be detected when the maximum pressure during the expansion process of the artificial muscle falls below a predetermined threshold. However, in this case, it would be difficult to secure space on the robot body to install the pressure measuring unit. Furthermore, the signal cable connecting the pressure measuring unit to the drive unit would be added to the compressed gas tube, reducing its flexibility and increasing the coefficient of friction and weight, thus reducing the propulsion force of the robot body.

[0007] Therefore, it is conceivable to configure the system so that the internal pressure of the artificial muscle is indirectly monitored from the control unit by installing a pressure measuring unit between the gas supply unit and the tube. However, the difference between the maximum pressure of the artificial muscle during normal operation and during bursting is extremely small, for example, around 15-20 kPa. Furthermore, the maximum pressure of the artificial muscle during expansion is affected by various disturbances, such as the aging of the tube and artificial muscle, unpredictable pressure loss caused by the deformation of the tube's cross-section from circular to elliptical at bends in the tube, changes in the reaction force the artificial muscle receives from the tube due to differences in the inner diameter of the tube depending on the location, and fluctuations in the primary side pressure supplying compressed gas to the gas supply unit (for example, the pressure of an air compressor installed in the factory). As a result, it is difficult to accurately detect a burst in the artificial muscle based on the pressure detected by the pressure measuring unit installed on the control unit side.

[0008] This invention has been made in view of these problems, and its purpose is to provide a pipe-mounted robot system that can detect bursts of artificial muscles more robustly against disturbances while having the pressure measuring unit located on the control unit side. [Means for solving the problem]

[0009] The pipe-moving robot system of the present invention comprises a robot body equipped with an artificial muscle that expands radially and contracts axially when compressed gas is supplied, a gas supply unit connected to the artificial muscle via a flexible tube, and a control unit that controls the operation of the gas supply unit, wherein the robot body moves inside a pipe using the artificial muscle as a driving source when compressed gas is supplied from the gas supply unit to the artificial muscle, and a pressure measuring unit provided between the gas supply unit and the tube acquires a first pressure measured by the pressure measuring unit at a first timing of the expansion process of the artificial muscle and a second pressure measured by the pressure measuring unit at a second timing different from the first timing of the expansion process of the artificial muscle, and the first pressure and the second pressure and The difference and the slope calculated from the time from the first timing to the second timingThe invention is characterized by having a detection unit that detects whether or not the artificial muscle has burst based on [a certain condition].

[0010] In the pipe-moving robot system of the present invention, the control unit is configured to supply compressed gas in a pattern from the gas supply unit to the artificial muscle to repeatedly expand and contract the artificial muscle, and the detection unit preferably acquires at least one of the first pressure and the second pressure for each expansion and contraction cycle of the artificial muscle to detect whether or not the artificial muscle has burst.

[0011] In the pipe-moving robot system of the present invention, it is preferable that the detection unit acquires the first pressure in the first half of the expansion process of the artificial muscle and the second pressure in the second half of the expansion process of the artificial muscle.

[0014] In the above configuration, the pipe-mobile robot system of the present invention preferably further includes a fixed pressure regulator provided between the gas supply unit and the pressure measuring unit. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a pipe-in-pipe mobile robot system that can detect artificial muscle bursts more robustly against disturbances while having the pressure measuring unit located on the control unit side. [Brief explanation of the drawing]

[0016] [Figure 1] This diagram shows the configuration of a pipe-mounted mobile robot system according to one embodiment of the present invention. [Figure 2] Figure 1 shows the pipe-mobile robot system, where (a) is a side view of the artificial muscle in its natural state and (b) is a side view of the artificial muscle in its inflated state. [Figure 3] This figure shows the control system of the in-pipe mobile robot system shown in Figure 1. [Figure 4]This is a diagram schematically illustrating the actuation patterns of a plurality of artificial muscles when the robot main body moves forward by peristaltic motion. [Figure 5] This is a characteristic diagram showing changes in pressure and flow rate during the expansion process of an artificial muscle under normal conditions. [Figure 6] This is a characteristic diagram showing changes in pressure and flow rate during the expansion process of an artificial muscle at the time of burst. [Figure 7] This is a diagram showing the first timing at which the detection unit detects the first pressure and the second timing at which the detection unit detects the second pressure. [Mode for Carrying Out the Invention]

[0017] Hereinafter, the in-pipe mobile robot system according to the present invention will be described in detail by way of example with reference to the drawings.

[0018] An in-pipe mobile robot system 1 according to one embodiment of the present invention shown in Fig. 1 is used for various applications such as inspection and cleaning inside a meandering pipe 2 (see Fig. 3 and Fig. 4) such as an air duct for an air conditioner and various pipes provided in office buildings, factories, detached houses and the like.

[0019] The in-pipe mobile robot system 1 includes a robot main body 10 and a control unit 20.

[0020] The robot main body 10 is provided with an artificial muscle 11 that expands in the radial direction and contracts in the axial direction when compressed gas is supplied. The robot main body 10 is configured to be able to move inside the pipe 2 using the artificial muscle 11 as a drive source. The compressed gas means a gas pressurized to a pressure higher than the atmospheric pressure.

[0021] In the present embodiment, the robot main body 10 is also referred to as an earthworm-type robot, a peristaltic robot, or the like, and includes seven artificial muscles 11 (only four artificial muscles 11 are shown in Figure 1), and has an elongated shape extending along the axis O. When the robot main body 10 is also referred to as an earthworm-type robot, a peristaltic robot, or the like, the robot main body 10 only needs to include at least three artificial muscles 11. The robot main body 10 can move in the axial direction (the direction along the axis O) inside the pipe 2. That is, the robot main body 10 can move forward inside the pipe 2 using these seven artificial muscles 11 as drive sources. The robot main body 10 may be configured to be capable of moving forward inside the pipe 2 and also capable of moving backward.

[0022] The artificial muscle 11 includes a cylindrical portion 11a formed in a cylindrical shape centered on the axis O by an elastic body such as various types of rubber. Both axial end portions of the cylindrical portion 11a are closed. Inside the cylindrical portion 11a, a plurality of fiber bundles (not shown) having high tensile strength are arranged along the axial direction. Thereby, the cylindrical portion 11a can be elastically deformed so as to expand in the radial direction, but elastic deformation in the direction extending in the axial direction is restricted. Therefore, as shown in Figure 2(a), the artificial muscle 11 is in a natural state (cylindrical state) when compressed gas such as compressed air is not supplied into the cylindrical portion 11a, and as shown in Figure 2(b), when compressed gas such as compressed air is supplied into the cylindrical portion 11a, the artificial muscle 11 operates so as to expand in the radial direction and contract in the axial direction to be in an expanded state. The outer diameter of the artificial muscle 11 in the natural state is smaller than the inner diameter of the pipe 2 that is the movement target, and the outer diameter of the artificial muscle 11 in the expanded state is larger than the inner diameter of the pipe 2 that is the movement target. Further, when the compressed gas inside the cylindrical portion 11a is discharged from the expanded state shown in Figure 2(b), the artificial muscle 11 contracts in the radial direction and extends in the axial direction by the elastic force of the cylindrical portion 11a, and can return to the original shape, that is, the natural state. Each of the artificial muscles 11 can be individually operated in patterns.

[0023] The artificial muscle 11 can have various configurations, such as a so-called McKibben type in which the outside of a cylindrical elastic body is covered with sleeve-shaped woven fibers, as long as it is configured to expand radially and contract axially when compressed gas is supplied.

[0024] As shown in Figures 1 and 2, adjacent artificial muscles 11 are connected to each other axially by a connecting portion 12. In this embodiment, the connecting portion 12 is a universal joint. As a result, the robot body 10 can bend at the portion of the connecting portion 12. Therefore, when the robot body 10 moves inside the pipe 2, even if the pipe 2 is bent, the robot body 10 can move along the bent pipe 2 because the space between adjacent artificial muscles 11 bends at the connecting portion 12.

[0025] In this embodiment, a universal joint is used as the connecting portion 12, but it is not limited to this as long as it connects adjacent artificial muscles 11 in a bendable manner.

[0026] The robot body 10 may be configured with multiple brushes 13 spaced apart in the axial direction. In this embodiment, each artificial muscle 11 is provided with a brush 13 in a substantially annular shape centered on the axis O at both ends in the axial direction. By providing multiple brushes 13, the robot body 10 can efficiently move along the pipe 2 by ensuring that it is supported approximately in the center of the pipe 2 by the multiple brushes 13 when moving inside the pipe 2. In addition, by providing brushes 13, the robot body 10 can clean the inside of the pipe 2 by collecting foreign matter (dirt) such as debris attached to the inner surface of the pipe 2 with the brushes 13 when moving inside the pipe 2.

[0027] In this embodiment, the robot body 10 is provided with multiple brushes 13, but other members such as flange-shaped or umbrella-shaped synthetic rubber may be provided instead of the brushes 13, as long as they have a substantially annular shape centered on the axis O. Alternatively, the robot body 10 may be configured without multiple brushes 13 or other members having a substantially annular shape centered on the axis O. Furthermore, the robot body 10 may be configured to have a camera at its tip, and the pipe-in-machine robot system 1 may be used for inspecting the inside of the pipe 2.

[0028] The control unit 20 controls the operation of the robot body 10. As shown in Figure 3, the control unit 20 includes a gas supply unit 21, a pressure measuring unit 22, a control unit 23, and a detection unit 24.

[0029] In this embodiment, the control unit 20 is configured as a single unit with the gas supply unit 21, pressure measuring unit 22, control unit 23, and detection unit 24 housed in a single housing 25. However, the control unit 20 may not consist of the gas supply unit 21, pressure measuring unit 22, control unit 23, and detection unit 24 housed in a single housing 25, but rather each component may be configured separately or partially individually.

[0030] The gas supply unit 21 supplies compressed gas to the artificial muscle 11 and is connected to the artificial muscle 11 via a flexible tube 30. That is, the gas supply unit 21 can supply compressed gas to the inside of the artificial muscle 11, i.e., the cylindrical portion 11a, via the tube 30. The tube 30 has an appropriate length (approximately 20 m in this embodiment) corresponding to the length of the pipe 2 on which the robot body 10 moves, and can be easily bent along the curved portion of the pipe 2.

[0031] In this embodiment, the gas supply unit 21 is equipped with seven on-off valves 21a (only three on-off valves 21a are shown in Figure 3) corresponding to seven artificial muscles 11 (only five artificial muscles 11 are shown in Figure 3). The seven on-off valves 21a are provided between the tube 30 connected to the corresponding artificial muscle 11 and the pressure source 40, such as an air compressor, which supplies compressed gas (compressed air). That is, although only one tube 30 is shown between the robot body 10 and the control unit 20 for simplicity in Figures 1 and 2, in reality, seven tubes 30 are provided between the robot body 10 and the control unit 20. These seven tubes 30 may be bundled together using a harness or cover. For example, solenoid valves can be used as the seven on-off valves 21a. The gas supply unit 21 can supply compressed gas supplied from the pressure source 40 to the inside of the cylindrical portions 11a of the seven artificial muscles 11 individually in a predetermined pattern via the seven on-off valves 21a and corresponding tubes 30, by individually opening and closing the seven on-off valves 21a.

[0032] Although not shown in detail, the gas supply unit 21 has multiple exhaust valves corresponding to each of the multiple tubes 30, and after stopping the supply of compressed gas to the artificial muscle 11, the compressed gas inside the cylindrical section 11a can be exhausted to the outside through the exhaust valves. For example, solenoid valves can be used as exhaust valves. In addition, the exhaust valves may be provided individually for each of the multiple tubes 30, separate from the gas supply unit 21.

[0033] In this embodiment, the pressure source 40 is a primary pressure source provided separately from the control unit 20, such as an air pressure compressor installed as equipment in a factory or building, but it may also be provided integrally with the control unit 20.

[0034] The pressure measuring unit 22 is provided between the gas supply unit 21 and the tube 30. In this embodiment, seven pressure measuring units 22 (only three pressure measuring units 22 are shown in Figure 3) are provided, corresponding to seven artificial muscles 11. Each of the seven pressure measuring units 22 is provided between the tube 30 connected to the corresponding artificial muscle 11 and the on / off valve 21a of the gas supply unit 21 corresponding to that tube 30. Therefore, each of the seven pressure measuring units 22 can individually measure the pressure inside the corresponding artificial muscle 11, i.e., the pressure inside the cylindrical portion 11a. Each of the seven pressure measuring units 22 is connected to the control unit 23, and the pressure measurement data measured by the seven pressure measuring units 22 is input to the control unit 23. In this way, the pipe-moving robot system 1 according to this embodiment is configured to allow indirect monitoring of the pressure inside the artificial muscles 11 provided in the robot body 10 from the control unit 23 (control unit 20) side by providing the pressure measuring unit 22 between the gas supply unit 21 and the tube 30.

[0035] The control unit 23 is composed of a computer equipped with a CPU (Central Processing Unit), memory, etc. The control unit 23 is connected to the gas supply unit 21 and controls the operation of the gas supply unit 21. More specifically, the control unit 23 controls the operation of the seven on-off valves 21a that make up the gas supply unit 21 by outputting command signals obtained by the CPU from the pressure measurement data input from the seven pressure measurement units 22, programs stored in memory, etc. to the gas supply unit 21.

[0036] In this embodiment, the control unit 23 is configured to supply compressed gas from the gas supply unit 21 to the artificial muscles 11 in a pattern, causing the artificial muscles 11 to repeatedly expand and contract. More specifically, the control unit 23 is configured to control the operation of seven on-off valves 21a that make up the gas supply unit 21 so that the seven artificial muscles 11 alternately deform in a pattern between a natural state and an expanded state. As a result, the seven artificial muscles 11 as a whole perform peristaltic motion in a pattern, allowing the robot body 10 to move inside the pipe 2. Thus, the robot body 10 is configured to move inside the pipe 2 using the artificial muscles 11 as a driving source when compressed gas is supplied to the artificial muscles 11 from the gas supply unit 21.

[0037] Here, the natural state of the artificial muscle 11 when the robot body 10 moves is when compressed gas is not supplied from the gas supply unit 21 to the inside of the cylindrical portion 11a of the artificial muscle 11, and the inside of the cylindrical portion 11a becomes atmospheric pressure, resulting in the cylindrical portion 11a remaining cylindrical without expansion (the state shown in Figure 2(a)). On the other hand, the expanded state of the artificial muscle 11 when the robot body 10 moves is when compressed gas is supplied from the gas supply unit 21 to the inside of the cylindrical portion 11a of the artificial muscle 11, and the cylindrical portion 11a expands radially until the pressure inside the cylindrical portion 11a reaches a predetermined value (the state shown in Figure 2(b)). As described above, when the artificial muscle 11 is in the expanded state, it can contact the inner circumferential surface of the tube 2 and hold the robot body 10 in the tube 2.

[0038] The control unit 20 may be configured with a fixed pressure regulator 26 between the gas supply unit 21 and the pressure measuring unit 22. In this embodiment, seven fixed pressure regulators 26 (only three fixed pressure regulators 26 are shown in Figure 3) are provided, corresponding to seven pressure measuring units 22. Each of the seven fixed pressure regulators 26 is provided between the corresponding pressure measuring unit 22 and the on-off valve 21a of the gas supply unit 21 corresponding to that pressure measuring unit 22. By providing the fixed pressure regulators 26 between the gas supply unit 21 and the pressure measuring unit 22, the pressure of compressed gas can be adjusted to the required value and supplied from the gas supply unit 21 to the artificial muscle 11. The seven fixed pressure regulators 26 each have a characteristic (droop characteristic) in which the set pressure decreases as the flow rate of compressed gas increases.

[0039] Figure 4 shows an example of the peristaltic movement pattern of the seven artificial muscles 11 when the robot body 10 moves axially to one side (left side in Figure 4) inside the pipe 2.

[0040] First, as shown in Figure 4(a), the leftmost (frontmost) artificial muscle 11 and the second artificial muscle 11 from the left in Figure 4 are expanded radially and then contracted axially. The two expanded artificial muscles 11 each come into contact with the inner surface of the tube 2 over their entire circumference. As a result, the robot body 10 is held in the axial direction by the two expanded artificial muscles 11.

[0041] Next, from the state shown in Figure 4(a), as shown in Figure 4(b), the leftmost artificial muscle 11 is returned to its original natural state, while the third artificial muscle 11 from the left is expanded radially and contracted axially. At this time, the second artificial muscle 11 from the left is in contact with the inner surface of the tube 2, maintaining its axial position. As the leftmost artificial muscle 11 contracts radially and extends axially to return to its natural shape, the left end (front end) of the robot body 10 moves to the left from the position shown in Figure 4(a). Also, as the third artificial muscle 11 from the left expands radially and contracts axially while the second artificial muscle 11 from the left is in contact with the inner surface of the tube 2, maintaining its axial position, the right end (rear end) of the robot body 10 also moves to the left from the position shown in Figure 4(a).

[0042] Next, from the state shown in Figure 4(b), as shown in Figure 4(c), the second artificial muscle 11 from the left is returned to its original natural state, while the fourth artificial muscle 11 from the left is expanded radially and contracted axially. At this time, the third artificial muscle 11 from the left is in contact with the inner circumferential surface of the tube 2, maintaining its axial position. As the second artificial muscle 11 from the left contracts radially and extends axially to return to its natural shape, the left end (front end) of the robot body 10 moves further to the left from the position shown in Figure 4(b). Also, as the fourth artificial muscle 11 from the left expands radially and contracts axially while the third artificial muscle 11 from the left is in contact with the inner circumferential surface of the tube 2, the right end (rear end) of the robot body 10 also moves further to the left from the position shown in Figure 4(b).

[0043] The artificial muscles 11 are then activated in the same pattern until the rightmost artificial muscle 11 is reached. Once the pattern reaches the rightmost artificial muscle 11, the robot body 10 returns to its initial state as shown in Figure 4(d), and the seven artificial muscles 11 are then activated in the same pattern.

[0044] In this way, by controlling the gas supply unit 21 to cause the seven artificial muscles 11 to perform peristaltic movements in the pattern described above, the robot body 10 can move forward inside the pipe 2 toward the left in Figure 4. Conversely, by controlling the gas supply unit 21 to operate the seven artificial muscles 11 in a pattern reversed from the pattern shown in Figure 4, the robot body 10 can move backward inside the pipe 2 toward the right in Figure 4.

[0045] Furthermore, the peristaltic movement pattern of the seven artificial muscles 11 when the robot body 10 moves is not limited to the above; other patterns are also acceptable as long as they allow the robot body 10 to move.

[0046] The detection unit 24 is provided to detect whether or not the artificial muscle 11 has burst (ruptured). In this embodiment, the detection unit 24 is provided as one function executed in the control unit 23, which is configured as a computer. That is, the detection unit 24 is part of the control unit 23. Alternatively, the detection unit 24 may be provided as one function of a computer separate from the control unit 23, which is connected to the control unit 23.

[0047] Here, during the expansion process when the artificial muscle 11 is not bursting (when there is no leakage of compressed gas from the artificial muscle 11), as shown in Figure 5, when the on-off valve 21a is opened and the supply of compressed gas from the gas supply unit 21 to the artificial muscle 11 begins, the flow rate of compressed gas supplied to the inside of the artificial muscle 11 increases, and the pressure inside the artificial muscle 11 rapidly rises to a certain pressure. Then, as the expansion of the artificial muscle 11 progresses, the pressure inside the artificial muscle 11 gradually increases, and the flow rate of compressed gas supplied to the inside of the artificial muscle 11 decreases. When the pressure inside the artificial muscle 11 reaches a predetermined maximum value, the flow rate of compressed gas supplied to the inside of the artificial muscle 11 becomes 0. In this embodiment, when a fixed pressure regulator 26 is provided, the predetermined maximum value of the pressure inside the artificial muscle 11 becomes the set value of the fixed pressure regulator 26.

[0048] On the other hand, during the expansion process when the artificial muscle 11 bursts (when compressed gas leaks from the artificial muscle 11), as shown in Figure 6, when the on-off valve 21a is opened and the supply of compressed gas from the gas supply unit 21 to the artificial muscle 11 begins, the flow rate of compressed gas supplied into the artificial muscle 11 increases and the pressure inside the artificial muscle 11 rapidly rises to a certain level. However, thereafter, because the compressed gas supplied into the artificial muscle 11 leaks out, the pressure inside the artificial muscle 11 does not rise to a predetermined maximum value and remains at approximately a constant value. In particular, in the case of a configuration with a fixed pressure regulator 26 as in this embodiment, the fixed pressure regulator 26 has a characteristic of decreasing pressure as the flow rate increases (droop characteristic), so the pressure inside the artificial muscle 11 does not rise to a predetermined maximum value under normal conditions and remains at a pressure sufficiently lower than the maximum pressure under normal conditions.

[0049] Therefore, as shown in Figure 7, when comparing the internal pressure of the artificial muscle 11 during the expansion process under normal conditions (no leak) and during bursts (with leaks), after the internal pressure of the artificial muscle 11 rises rapidly to a certain level, the difference between the normal pressure and the burst pressure gradually increases as the expansion process progresses. In particular, when comparing the difference between the normal pressure and the burst pressure in the first half of the expansion process with the difference between the normal pressure and the burst pressure in the second half of the expansion process, the latter becomes sufficiently large.

[0050] The expansion process of the artificial muscle 11 is defined as the process from when the on-off valve 21a opens and the supply of compressed gas from the gas supply unit 21 to the artificial muscle 11 begins until the on-off valve 21a closes and the supply of compressed gas from the gas supply unit 21 to the artificial muscle 11 stops.

[0051] The detection unit 24 is configured to take into account the difference between the normal pressure and the burst pressure shown in Figure 7, acquire a first pressure measured by the pressure measurement unit 22 at a first timing during the expansion process of the artificial muscle 11, and a second pressure measured by the pressure measurement unit 22 at a second timing that differs from the first timing during the expansion process of the artificial muscle 11, and to detect whether or not the artificial muscle 11 has burst based on the first pressure and the second pressure.

[0052] Here, the first timing is a timing within the range of the expansion process after a certain amount of time has elapsed since the opening of the valve 21a and the start of the expansion process of the artificial muscle 11, and the second timing is a timing within the range of the expansion process after a longer amount of time has elapsed than the first timing since the opening of the valve 21a and the start of the expansion process of the artificial muscle 11.

[0053] In this embodiment, the detection unit 24 is configured to acquire a first pressure in the first half of the expansion process of the artificial muscle 11 and a second pressure in the second half of the expansion process of the artificial muscle 11, by setting a first timing in the first half of the expansion process of the artificial muscle 11 and a second timing in the second half of the expansion process of the artificial muscle 11. More specifically, in this embodiment, the first timing is set to the timing when the flow rate of compressed gas supplied from the gas supply unit 21 to the artificial muscle 11 is at its maximum and the pressure is locally at its minimum (bottom) due to the characteristics of the fixed pressure regulator 26. This setting makes it possible to maximize the detection sensitivity (difference between normal and burst conditions) by making maximum use of the pressure drop characteristics of the fixed pressure regulator 26 while suppressing the influence of transient surge pressure (noise) that occurs immediately after opening the on-off valve 21a. In addition, in this embodiment, the second timing is set at the completion or near the completion of the expansion process in the same expansion and contraction cycle of the artificial muscle 11 as the first timing. This makes the difference between the first pressure and the second pressure larger, thereby increasing the detection sensitivity.

[0054] The detection unit 24 can detect whether or not the artificial muscle 11 has burst based on the first pressure and the second pressure, for example, based on the difference between the first pressure and the second pressure. In this case, the detection unit 24 should be configured to determine that the artificial muscle 11 has burst when the difference between the first pressure and the second pressure falls below a predetermined threshold. For example, the difference between the first pressure and the second pressure during normal operation when the artificial muscle 11 is not bursting is sufficiently larger than the difference between the first pressure and the second pressure when the artificial muscle 11 bursts. By setting a threshold between these differences, it is possible to determine that the artificial muscle 11 has burst when the difference between the first pressure and the second pressure falls below that threshold.

[0055] The detection of whether or not the artificial muscle 11 has burst, based on the first pressure and the second pressure by the detection unit 24, may be performed based on a slope calculated from the difference between the first pressure and the second pressure and the time from the first timing to the second timing. In this case, the slope can be calculated by dividing the difference between the first pressure and the second pressure by the time from the first timing to the second timing, and the detection unit 24 can be configured to determine that the artificial muscle 11 has burst when this slope falls below a predetermined threshold.

[0056] Although not shown in detail, the control unit 20 is configured to inform the user that the detection unit 24 has detected a burst in the artificial muscle 11, for example, by sounding a buzzer, illuminating a warning light, or displaying a message on the monitor indicating that a burst has been detected. The control unit 20 may also be configured to automatically stop the movement of the robot body 10 when the detection unit 24 detects a burst in the artificial muscle 11.

[0057] The first pressure measured at the first timing of the expansion process of the artificial muscle 11 in the detection unit 24 is a pressure that reflects all disturbance factors at that time, such as the aging deterioration of the tube 30 and the artificial muscle 11, the unpredictable pressure loss caused by the deformation of the cross-section of the tube 30 from circular to elliptical at bending points of the pipe 2, the change in the reaction force that the artificial muscle 11 receives from the pipe 2 due to differences in the inner diameter of the pipe 2 depending on the location, and pressure fluctuations in the pressure source 40 that supplies compressed gas to the gas supply unit 21. Therefore, for each cycle in which the artificial muscle 11 expands and contracts, the first pressure measured at the first timing of the expansion process of the artificial muscle 11 is used as a reference, and the second pressure measured at a second timing that differs from the first timing is compared with the first pressure. This cancels out the fluctuations in the absolute value of the pressure of the artificial muscle 11 due to the above disturbance factors, and the presence or absence of a burst in the artificial muscle 11 can be accurately detected without being affected by the disturbance factors. In other words, for example, to suppress control divergence due to delay caused by using a long tube 30, the pressure of the primary side pressure source 40 is fed back in real time to correct the threshold for detecting bursts in the artificial muscle 11. Without using complex control for disturbance factors, the presence or absence of a burst in the artificial muscle 11 can be detected more easily and accurately by simply comparing the first pressure and the second pressure.

[0058] Thus, according to the pipe-in-robot system 1 of this embodiment, the pressure measuring unit 22 is provided on the side of the control unit 23 (the side of the control unit 20), and the detection unit 24 acquires a first pressure measured by the pressure measuring unit 22 at a first timing in the expansion process of the artificial muscle 11 and a second pressure measured by the pressure measuring unit 22 at a second timing that differs from the first timing in the expansion process of the artificial muscle 11, and detects whether or not the artificial muscle 11 has burst based on the first pressure and the second pressure. Therefore, even though the pressure measuring unit 22 is provided on the side of the control unit 23 (the side of the control unit 20), it is possible to detect whether or not the artificial muscle 11 has burst more robustly against disturbance factors.

[0059] Furthermore, according to the pipe-moving robot system 1 of this embodiment, there is no need to provide a pressure measuring unit 22 on the robot body 10, so the robot body 10 can be made smaller and lighter, and the flexibility of the tube 30 can be ensured.

[0060] Furthermore, according to the pipe-mounted robot system 1 of this embodiment, the presence or absence of a burst in the artificial muscle 11 can be detected more robustly against external disturbances, allowing for earlier and more accurate detection of the presence or absence of a burst. This makes it possible to stop the robot body 10 immediately after the artificial muscle 11 bursts, and to safely and quickly evacuate and retrieve the robot body 10 from inside the pipe 2.

[0061] In the pipe-moving robot system 1 according to this embodiment, as described above, the detection unit 24 is configured to acquire a first pressure in the first half of the expansion process of the artificial muscle 11 and a second pressure in the second half of the expansion process of the artificial muscle 11. By making the difference between the first pressure and the second pressure larger depending on whether or not there is a burst, the detection sensitivity or detection accuracy of the artificial muscle 11 by the detection unit 24 can be improved.

[0062] Furthermore, in the pipe-mobile robot system 1 according to this embodiment, as described above, a fixed pressure regulator 26 is provided between the gas supply unit 21 and the pressure measurement unit 22. This allows the difference between the first pressure and the second pressure to become larger depending on whether or not a burst occurs, thereby improving the detection sensitivity or accuracy of the artificial muscle 11 by the detection unit 24.

[0063] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention.

[0064] For example, in the above embodiment, the detection unit 24 acquires the first pressure and the second pressure in the same cycle of expansion and contraction of the artificial muscle 11. However, the detection unit 24 may be configured to acquire at least one of the first pressure and the second pressure for each cycle of expansion and contraction of the artificial muscle 11, for example, by acquiring the first pressure in one cycle of expansion and contraction of the artificial muscle 11 and the second pressure in the next cycle, and so on.

[0065] Furthermore, in the above embodiment, the detection unit 24 acquires the first pressure in the first half of the expansion process of the artificial muscle 11 and the second pressure in the second half of the expansion process of the artificial muscle 11. However, the system is not limited to this configuration, and the first timing for acquiring the first pressure and the second timing for acquiring the second pressure can be set to any appropriate timing as long as they are different from each other.

[0066] Furthermore, although a fixed pressure regulator 26 is provided between the gas supply unit 21 and the pressure measuring unit 22 in the above embodiment, a configuration without a fixed pressure regulator 26 is also possible.

[0067] Furthermore, the compressed gas supplied to the artificial muscle 11 by the gas supply unit 21 is not limited to compressed air, but may be other compressed gases such as nitrogen. [Explanation of Symbols]

[0068] 1. In-pipe mobile robot system 2 tubes 10 Robot body 11 Artificial Muscle 11a Cylindrical part 12 Connecting part 13 brushes 20 Control Units 21 Gas supply unit 21a Shut-off valve 22 Pressure measuring section 23 Control Unit 24 Detection unit 25 cabinets 26 Fixed pressure regulator 30 tubes 40 Pressure source O axis

Claims

1. A pipe-moving robot system comprising: a robot body equipped with artificial muscles that expand radially and contract axially when compressed gas is supplied; a gas supply unit connected to the artificial muscles via a flexible tube; and a control unit that controls the operation of the gas supply unit, wherein the robot body moves inside a pipe using the artificial muscles as a driving source when compressed gas is supplied from the gas supply unit to the artificial muscles, A pressure measuring unit is provided between the gas supply unit and the tube, A pipe-moving robot system characterized by having a detection unit that acquires a first pressure measured by the pressure measuring unit at a first timing during the expansion process of the artificial muscle and a second pressure measured by the pressure measuring unit at a second timing different from the first timing during the expansion process of the artificial muscle, and detects whether or not the artificial muscle bursts based on the difference between the first pressure and the second pressure and the slope calculated from the time from the first timing to the second timing.

2. The control unit is configured to supply compressed gas in a pattern from the gas supply unit to the artificial muscle, causing the artificial muscle to repeatedly expand and contract. The pipe-in-robot system according to claim 1, wherein the detection unit acquires at least one of the first pressure and the second pressure for each expansion and contraction cycle of the artificial muscle to detect whether or not the artificial muscle has burst.

3. The pipe-in-robot system according to claim 2, wherein the detection unit acquires the first pressure in the first half of the expansion process of the artificial muscle and acquires the second pressure in the second half of the expansion process of the artificial muscle.

4. The pipe-in-robot system according to claim 1, further comprising a fixed pressure regulator provided between the gas supply unit and the pressure measuring unit.

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