Actuator angle estimation device and actuator angle estimation method

Abstract

To easily obtain a bending angle of a fluid pressure actuator.SOLUTION: An actuator angle estimation device 10 includes a tube member 24 that has a first chamber 25A and a second chamber 25B which are spaced apart from each other, disposed along the axial direction, and arranged parallel to each other. The actuator bend angle estimation device estimates the bend angle of an elongated actuator body section 22 that is bent as a result of one side of a tube wall being shortened in the axial direction in response to a rise in the internal pressure of the first chamber 25A. The actuator bend angle estimation device 10 additionally comprises: a fluid supply unit that supplies a fluid to the first chamber 25A; a pressure sensor 62 that acquires the internal pressure of the second chamber 25B; and an angle estimation unit that estimates the bend angle of the actuator body 22 on the basis of the internal pressure of the second chamber 25B in a sealed state acquired by the pressure sensor 62.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an actuator angle estimation device and an actuator angle estimation method for a fluid pressure actuator.

Background Art

[0002] Conventionally, as a fluid pressure actuator, a McKibben type having a rubber tube and a sleeve (woven with high-tensile fibers) covering the outer surface thereof is known. Such a McKibben type fluid pressure actuator can change the length along the axial direction of the rubber tube and the sleeve. Further, a technique has been proposed in which a restraint member is provided in a part of the circumferential direction from one end side to the other end side in the axial direction of the rubber tube, thereby shortening and curving and deforming the side of the fluid pressure actuator where the restraint member is not provided (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Regarding such a fluid pressure actuator, various usage methods have been proposed. For example, it has been proposed to use it as a finger that grips an object by bending deformation by combining a plurality of them. When used in this way, it is easy to use if the bending angle of the fluid pressure actuator can be obtained. Generally, an angle sensor is used to measure the bending angle. However, since the angle sensor is directly attached to the actuator, wiring is required, and waterproofing is required during cleaning, so the configuration becomes complicated.

[0005] In view of the above facts, an object of the present disclosure is to provide an actuator angle estimation device and an actuator angle estimation method capable of obtaining the angle of a bending fluid pressure actuator with a simple configuration.

Means for Solving the Problems

[0006] To achieve the above object, an actuator angle estimation device according to a first aspect includes a tube member having a first chamber and a second chamber that are isolated from each other, arranged along the axial direction, and arranged parallel to each other. The actuator angle estimation device estimates the bending angle of a long actuator body portion that is curved by the shortening of one side of the tube wall in the axial direction due to the increase in the internal pressure of the first chamber. The actuator angle estimation device includes a fluid supply unit that supplies fluid to the first chamber, a pressure sensor that acquires the internal pressure of the second chamber, and an angle estimation unit that estimates the bending angle of the actuator body based on the internal pressure of the sealed second chamber acquired by the pressure sensor.

[0007] The actuator angle estimation device according to the first aspect includes a tube member having a first chamber and a second chamber that are isolated from each other, arranged along the axial direction, and arranged parallel to each other. When the fluid is supplied from the fluid supply unit to the first chamber with the second chamber in a sealed state, the internal pressure of the first chamber increases and the actuator body portion bends. Following this bending, the sealed second chamber undergoes bending deformation. The inventor focused on the relationship between the internal pressure of the second chamber at this time and the bending angle of the actuator body portion, and found that the internal pressure of the second chamber changes according to the bending angle of the actuator body portion. Therefore, the internal pressure of the second chamber is acquired by the pressure sensor, and the angle estimation unit estimates the bending angle of the actuator body based on the internal pressure of the second chamber.

[0008] According to the actuator angle estimation device according to the first aspect, in this way, the bending angle of the fluid pressure actuator can be obtained with a simple configuration without using a conventional angle sensor.

[0009] In the actuator angle estimation device according to the second aspect, the second chamber is pre-pressurized higher than atmospheric pressure in the sealed state.

[0010] In this way, by applying a pre-pressure higher than atmospheric pressure to the second chamber, the influence of noise on angle estimation can be suppressed.

[0011] The actuator angle estimation method according to the third aspect includes a tube member having a first chamber and a second chamber that are isolated from each other and arranged in parallel along the axial direction. The actuator angle estimation method estimates the bending angle of a long actuator body portion in which one side of the tube wall is shortened and curved in the axial direction due to an increase in the internal pressure of the first chamber. The method supplies fluid to the first chamber with the second chamber in a sealed state, and estimates the bending angle of the actuator body portion based on the internal pressure of the sealed second chamber.

[0012] In the actuator angle estimation method according to the third aspect, when fluid is supplied to the first chamber with the second chamber in a sealed state, the internal pressure of the first chamber increases, and the actuator body portion bends. Following this bending, the sealed second chamber undergoes bending deformation. The inventor focused on the relationship between the internal pressure of the second chamber at this time and the bending angle of the actuator body portion, and found that the internal pressure of the second chamber changes according to the bending angle of the actuator body portion. Therefore, the bending angle of the actuator body is estimated based on the internal pressure of the second chamber.

[0013] According to the actuator angle estimation method of the second aspect, in this way, the bending angle of the fluid pressure actuator can be obtained with a simple configuration without using a conventional angle sensor.

[0014] In the actuator angle estimation method according to the fourth aspect, the second chamber is pre-pressurized higher than atmospheric pressure in the sealed state.

[0015] Thus, by applying a pre-pressure higher than the atmospheric pressure to the second chamber, the influence of noise on the angle estimation can be suppressed.

Advantages of the Invention

[0016] According to the present disclosure, the bending angle of the actuator can be easily obtained.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0018] Hereinafter, embodiments for realizing the technology of the present disclosure will be described in detail with reference to the drawings.

[0019] In addition, components and processes that perform the same functions may be given the same reference numerals throughout the drawings, and duplicate explanations may be omitted as appropriate. Further, the present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0020] As shown in FIG. 1, the actuator bending angle estimation device 10 of the present disclosure includes an air supply unit 60 as a fluid supply unit, a pressure sensor 62, and a control unit 64. The air supply unit 60 is connected to a first chamber 25A of a fluid pressure actuator 20 described later via a pipe 54, and supplies compressed air to the first chamber 25A. The pressure sensor 62 is connected to a second chamber 25B via a pipe 56, and is capable of measuring the internal pressure of the sealed second chamber 25B of the fluid pressure actuator 20. The air supply unit 60 and the pressure sensor 62 are connected to the control unit 64. The control unit 64 will be described later.

[0021] FIG. 2 shows a fluid pressure actuator 20 as a measurement target of the actuator bending angle estimation device 10 of the present disclosure. The fluid pressure actuator 20 includes an actuator main body 22 and sealing members 30A and 30B.

[0022] As also shown in FIG. 3, the actuator main body 22 has a tube member 24, a sleeve 26, a restraint member 28, a locking ring 34, and a caulking member 36.

[0023] The tube member 24 is composed of two tubes (a first tube 24A and a second tube 24B). A first chamber 25A is formed in the first tube 24A, and a second chamber 25B is formed in the second tube 24B. The first tube 24A and the second tube 24B are cylindrical members that can expand and contract due to elastic deformation, and expand and contract due to a change in the pressure of the internal fluid. In a state where the fluid pressure actuator 20 is assembled, the longitudinal directions of the first tube 24A and the second tube 24B coincide with the axial direction X. As shown in FIG. 4, the first chamber 25A and the second chamber 25B are arranged parallel to each other in a state where the fluid pressure actuator 20 is assembled.

[0024] Note that the tube member 24 can be made of an elastic material such as butyl rubber. As the fluid supplied to the tube member 24, air can be used. In this case, the fluid pressure actuator 20 becomes a pneumatic actuator. When the fluid pressure actuator 20 is hydraulically driven, it is preferably at least one selected from the group consisting of NBR (nitrile rubber) with high oil resistance, hydrogenated NBR, chloroprene rubber, and epichlorohydrin rubber.

[0025] The sleeve 26 is a cylindrical member that covers the outer periphery of the tube member 24. The sleeve 26 is a stretchable structure in which fiber cords oriented in a predetermined direction are woven, and the oriented cords intersect the axial direction X at a predetermined angle θ. By having such a shape, the sleeve 26 undergoes a pantograph deformation that changes the angle θ and follows the contraction and expansion of the tube member 24 while restricting the contraction and expansion of the tube member 24.

[0026] As the cords constituting the sleeve 26, it is preferable to use fiber cords of aromatic polyamide (aramid fiber) or polyethylene terephthalate (PET). However, it is not limited to such types of fiber cords, and for example, cords of other high-strength fibers such as PBO fiber (polyparaphenylene benzobisoxazole) may also be used.

[0027] The restraining member 28 is provided at the opposing portion between the first tube 24A and the second tube 24B. The restraining member 28 is in the shape of a long plate and is arranged such that its longitudinal direction is along the axial direction X of the tube member 24. While touching a part of the outer peripheries of the first tube 24A and the second tube 24B, it is arranged from one end to the other end of the tube member 24.

[0028] Note that the restraint member 28 is formed of a material that does not expand or contract under pressure and is capable of flexing and deforming in a direction in which the ends approach each other. As the restraint member 28, a so-called leaf spring can be used. The dimensions of the leaf spring are determined according to the size of the fluid pressure actuator 20, the required gripping force, and the like. Also, the material of the leaf spring is not particularly limited, but typically, a material that is easily flexibly deformed and resistant to compression, such as a metal such as stainless steel, may be used. Alternatively, it may be formed of a thin plate of carbon fiber reinforced plastic (CFRP) or the like.

[0029] The locking ring 34 is a ring-shaped member and is disposed outside the sleeve 26 so as to sandwich the sleeve 26 between it and a locking portion 58 to be described later, and locks the sleeve 26 to the semi-base end portion 40. Thereby, the sleeve 26 is folded back to the outer periphery via the locking ring 34. Note that the locking ring 34 can be made of a material such as metal, hard plastic, fiber, or rubber.

[0030] The caulking member 36 is disposed so as to cover a portion of the outer periphery of the actuator main body portion 22 where the insertion portion 50 is inserted, and crimps the actuator main body portion 22 to the insertion portion 50 to be described later. Thereby, the actuator main body portion 22 is fixed to the insertion portion 50 of a sealing member 30 to be described later. As the caulking member 36, a metal such as an aluminum alloy, brass, or iron can be used.

[0031] The sealing member 30 is divided into a first sealing member 30A and a second sealing member 30B in the middle of the arrangement direction Z. The first sealing member 30A and the second sealing member 30B have the same shape.

[0032] The first sealing member 30A has a semi-base end portion 40 and an insertion portion 50. The semi-base end portion 40 has a larger diameter than the insertion portion 50, and the insertion portion 50 protrudes toward the inner side in the axial direction X (the center side of the actuator main body portion 22) of the semi-base end portion 40. In the semi-base end portion 40, a flow path is formed that forms a part of the flow path R1 that penetrates in the axial direction X through the central portion in the radial direction of the insertion portion 50 from the connection hole H. A pipe 54 is connected to the connection hole H, and compressed air is supplied from the air supply portion 60 as a fluid supply portion to the flow path R1.

[0033] An insertion groove 42 is formed in the split surface 33 of the semi-base end portion 40. The end portion of the restraint member 28 is inserted into the insertion groove 42.

[0034] An attachment portion (not shown) is formed in the semi-base end portion 40, and the fluid pressure actuator 20 is fixed to a shaft member (not shown) via the attachment portion.

[0035] As shown in FIGS. 3 and 4, the insertion portion 50 has a bamboo shoot shape in which a plurality of tapered portions that taper toward the inner side in the axial direction X are formed continuously in the axial direction X. A through hole is formed in the insertion portion 50 along the axial direction X, and a part of the flow path R1 described above is formed by the through hole. One end of the first tube 24A is externally inserted into the insertion portion 50.

[0036] As the first sealing member 30A, a metal such as stainless steel can be preferably used, but it is not limited to such a metal, and a hard plastic material or the like may be used.

[0037] The second sealing member 30B has the same shape as the first sealing member 30A with a split surface 33 therebetween. In the semi-base end portion 40 of the second sealing member 30B, a flow path is formed that forms a part of a flow path R2 that penetrates in the axial direction X through the central portion in the radial direction of the insertion portion 50 from the connection hole H. One end of the second tube 24B is externally inserted into the insertion portion 50 of the second sealing member 30B. A tube 56 is connected to the connection hole H, and a pressure sensor 62 is connected to the second chamber 25B via the tube 56. The second chamber 25B is in a sealed state and is applied with a pre-pressure higher than the atmospheric pressure. As an example, the pre-pressure can be set to about 80 kPa to 120 kPa. The pressure sensor 62 is capable of measuring the internal pressure of the second chamber 25B.

[0038] The sealing member 31 provided on the other end side (the right side in the drawing in FIG. 2) in the axial direction X of the fluid pressure actuator 20 has a lid portion 38 and a pair of insertion portions 50. The lid portion 38 of the sealing member 31 is the same as the semi-base end portion 40 except that the connection hole H and the flow paths R and R2 are not formed in the semi-base end portion 40 of the sealing member 30 and the tip is in an R shape.

[0039] As shown in FIG. 5, the control unit 64 includes a CPU (Central Processing Unit) 71, a ROM (Read Only Memory) 72, a RAM (Random Access Memory) 73, an input / output interface (I / O) 74, and a storage unit 75.

[0040] The CPU 71, the ROM 72, the RAM 73, the storage unit 75, and the I / O 74 are respectively connected via a bus 76. An air supply unit 60, a pressure sensor 62, a display unit 66, an input unit 68, and other functional units are connected to the I / O 74. These functional units can communicate with the CPU 71 via the I / O 34.

[0041] As the storage unit 75, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), a flash memory, etc. are used. In the storage unit 75, a control program for controlling the fluid pressure actuator 20 and various data are stored. Note that this control program and various data may be stored in the ROM 72.

[0042] Next, the angle estimation in the actuator bending angle estimation device 10 of the present disclosure will be described.

[0043] The fluid pressure actuator 20 is used such that the sealing member 30 on one end side is fixed and the sealing member 30B on the other end side becomes a free end.

[0044] When an operation instruction for the fluid pressure actuator 20 is input from the input unit 68 to the control unit 64, the control unit 64 issues an instruction to the air supply unit 60 to supply compressed air. In response to this, the air supply unit 60 outputs compressed air, and the compressed air is supplied to the first chamber 25A through the pipe 54 and the flow path R1. When the compressed air flows in from the connection hole H, the pressure in the first chamber 25A rises. Due to the increase in the internal pressure, the first tube 24A elastically deforms and expands, the sleeve 26 deforms so that the angle θ increases, and a force acts in the direction in which the length of the actuator main body 22 shortens. At this time, since the shortening of the outer peripheral side wall where the restraining member 28 of the first tube 24A is arranged is restricted, the outer peripheral wall on the side where the restraining member 28 is not arranged shortens when viewed from the axial direction of the first tube 24A. As a result, the restraining member 28 bends and deforms, and as shown by the two-dot chain line in FIG. 4, the entire actuator main body 22 bends. The second tube 24B bends and deforms following this bending, and the internal pressure in the second chamber 25B rises.

[0045] The angle between the axial direction at the tip end portion (the portion of the sealing member 31) of the actuator main body 22 and the axial direction at the base end portion (the portion of the sealing member 30) of the actuator main body 22 during this bending is defined as the bending angle α.

[0046] At this time, the pressure sensor 62 measures the internal pressure of the second chamber 25B in a sealed state and outputs the internal pressure data to the control unit 64. In the control unit 64, the estimation process of the bending angle α is performed based on the internal pressure data. The bending angle α has a correlation with the internal pressure P of the second chamber 25B. For the fluid pressure actuator 20 to be used, the relationship between the bending angle α and the internal pressure P is obtained in advance. As an example, the relationship shown in FIG. 7 is obtained, and the bending angle α is estimated from this relationship based on the internal pressure data. The bending angle α obtained by the estimation process is output to the display unit 66.

[0047] In the actuator bending angle estimation device 10 of the present embodiment, since the bending angle α is estimated based on the internal pressure of the second chamber 25B, the bending angle α of the fluid pressure actuator 20 can be obtained without using a conventional angle sensor. The pressure sensor 62 does not need to be in close contact with the fluid pressure actuator 20 and can be provided at a distance, so that the fluid pressure actuator 20 itself can have a simple configuration. Further, compared with a conventional angle sensor, electrical wiring to the fluid pressure actuator 20 is also unnecessary, so that a simple configuration can be achieved.

[0048] Also, when the fluid pressure actuator 20 is driven, by applying a pre-pressure higher than the atmospheric pressure to the second chamber 25B, the influence of noise on the angle estimation can be suppressed.

[0049] <Modification Example>

[0050] In the above-described present embodiment, both the first chamber 25A and the second chamber 25B may be connected to the air supply unit 60 and also to the pressure sensor 62. In this case, as shown in FIG. 6, the pipe 54 is branched into pipes 54A and 54B, the pipe 56 is branched into pipes 56A and 56B, and three-way valves V1 and V2 are provided at each branching portion.

[0051] The fluid pressure actuator 20-2 in Fig. 6 can be bent in two directions, i.e., the Z+ side and the Z- side in Fig. 6. When bending to the Z+ side, open the pipe 54A side of the three-way valve V1 and the pipe 56B side of the three-way valve V2. Thereby, the fluid pressure actuator 20 can be bent to the Z+ side, and the bending angle can be estimated based on the internal pressure of the second chamber 25B.

[0052] Also, when bending to the Z- side, open the pipe 54B side of the three-way valve V1 and the pipe 56A side of the three-way valve V2. Thereby, the fluid pressure actuator 20 can be bent to the Z- side, and the bending angle can be estimated based on the internal pressure of the first chamber 25A.

Explanation of Reference Numerals

[0053] 10 Actuator Bending Angle Estimation Device 20 Fluid Pressure Actuator 22 Actuator Main Body Part 24 Tube Member 25A First Chamber 25B Second Chamber 60 Air Supply Unit (Fluid Supply Unit) 62 Pressure Sensor 64 Control Unit (Angle Estimation Unit)

Claims

1. An actuator angle estimation device comprising a tube member having a first chamber and a second chamber that are isolated from each other, arranged along the axial direction, and parallel to each other, and estimating a bending angle of a long actuator body portion in which one side of the tube wall is shortened and bent in the axial direction due to an increase in the internal pressure of the first chamber, a fluid supply unit that supplies fluid to the first chamber, a pressure sensor that acquires the internal pressure of the second chamber, and an angle estimation unit that estimates the bending angle of the actuator body portion based on the internal pressure of the second chamber in a sealed state acquired by the pressure sensor. An actuator angle estimation device comprising the above.

2. The second chamber has a pre-pressure higher than atmospheric pressure in a sealed state. The actuator angle estimation device according to Claim 1.

3. An actuator angle estimation method for estimating a bending angle of a long actuator body portion in which one side of the tube wall is shortened and bent in the axial direction due to an increase in the internal pressure of a first chamber, the method comprising a tube member having a first chamber and a second chamber that are isolated from each other and arranged parallel to each other along the axial direction, supplying fluid to the first chamber with the second chamber in a sealed state, and estimating the bending angle of the actuator body portion based on the internal pressure of the second chamber in the sealed state. An actuator angle estimation method.

4. The second chamber has a pre-pressure higher than atmospheric pressure in a sealed state. The actuator angle estimation method according to Claim 3.

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