Fluid pressure actuator and actuator control system

Abstract

To inhibit an excessive force from acting on a fluid pressure actuator and inhibit damage of an object.SOLUTION: A fluid pressure actuator 1 according to the disclosure includes: a cylindrical tube 11 which expands or contracts; a sleeve 12 which covers an outer peripheral surface of the tube 11, restricts axial expansion of the tube 11, and allows radial expansion of the tube 11; and a holding part 18 which is attached to the tip side as seen in the axial direction of the tube 11 and holds an object O. At least a portion, which holds the object O, of the holding part 18 is formed by an elastic member, and the holding part 18 has a contact detection part 120 which detects contact of the object.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to fluid pressure actuators and actuator control systems. [Background technology]

[0002] Conventionally, fluid pressure actuators that use gas or liquid to expand and contract a tube have been known. For example, Patent Document 1 discloses a fluid pressure actuator (a so-called McKibben type fluid pressure actuator) that has a rubber tube that expands and contracts using air pressure and a sleeve that covers the outer surface of the tube. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-088999 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the conventional fluid pressure actuators described above, there are cases where excessive force is applied to the fluid pressure actuator when it comes into contact with an object other than the object being held, or excessive force is applied to the object being held, and there is room for improvement in these areas.

[0005] The present disclosure has been made in view of the above circumstances, and aims to prevent excessive force from acting on a fluid pressure actuator and to prevent damage to an object. [Means for solving the problem]

[0006] The present disclosure has been made to solve the above-mentioned problems, and the fluid pressure actuator of the present disclosure is a fluid pressure actuator that is driven by fluid pressure and includes a cylindrical tube that expands and contracts, a sleeve that covers the outer surface of the tube and restricts axial extension of the tube while allowing radial extension, and a holding portion that is attached to the axial tip side of the tube and holds an object, and at least the portion of the holding portion that holds the object is made of an elastic material, and includes a contact detection portion that detects contact with an object. According to the fluid pressure actuator of the present disclosure, the object is held by an elastic member, thereby preventing damage or scratches to the object. Furthermore, since the holding unit is provided with a contact detection unit, abnormal contact such as excessive pressure being applied to the object or contact with an object other than the object can be easily detected, thereby improving the controllability of the fluid pressure actuator. Furthermore, damage to the fluid pressure actuator and the object O can be prevented.

[0007] Furthermore, the fluid pressure actuator preferably further includes a restraining member that restricts axial contraction of the tube, and the detection signal from the contact detector is preferably transmitted through or along the restraining member. By adopting such a configuration, the wiring member can be arranged within or along the relatively rigid restraining member that extends in the signal transmission direction within the fluid pressure actuator, ensuring a wiring path without adding any additional components other than the wiring member. Furthermore, breakage of the wiring member can be reduced.

[0008] In the fluid pressure actuator of the present disclosure, the restraint member is preferably a laminated plate having an intermediate conductive layer that transmits a detection signal from the contact detection unit. By using the wiring member as the intermediate layer of the restraint member, the wiring member is protected by the outer layer of the restraint member, thereby improving the reliability of the wiring member.

[0009] In the fluid pressure actuator of the present disclosure, it is preferable that the elastic member is a conductive member, and the contact detection unit is capable of detecting contact of an object by detecting the resistance value of the elastic member. By adopting such a configuration, the holding unit can be formed of a conductive member and used as a contact sensor, so that contact with the holding unit can be detected without incorporating a new sensor.

[0010] In the fluid pressure actuator of the present disclosure, the contact detection unit preferably includes a piezoelectric element. By adopting such a configuration, pressure in a predetermined direction at a predetermined position can be detected with a simple sensor, so that abnormal contact with a pressure greater than a predetermined pressure can be reliably detected.

[0011] Furthermore, an actuator control system according to the present disclosure is an actuator control system including any one of the fluid pressure actuators described above and a control unit that controls the fluid pressure actuator, and the control unit preferably determines that abnormal contact has occurred when the pressing force on the holding unit based on the detection signal from the contact detection unit is greater than a first threshold. By adopting such a configuration, abnormal contact, in which the holding unit applies excessive pressing force to the object or comes into contact with an object other than the object, can be recognized and the operation of the fluid pressure actuator can be quickly stopped. In this embodiment, forming the holding unit from an elastic material can prevent damage or scratches to the object, but it has been difficult to detect abnormal contact. However, the introduction of a contact detection unit makes it possible to quickly detect abnormal contact and stop the operation of the fluid pressure actuator.

[0012] Furthermore, in the actuator control system of the present disclosure, it is preferable that the control unit acquires detection signals from the contact detection units of the plurality of fluid pressure actuators, and determines that the object O is being held properly when the pressing force on the holding unit based on the detection signals from at least two of the fluid pressure actuators is equal to or greater than a second threshold and equal to or less than the first threshold. By employing such a configuration, it is possible to determine that the object O is being held properly by recognizing that the fluid pressure actuators are not applying excessive pressing force and that the object O is being clamped by the plurality of fluid pressure actuators with an appropriate pressing force.

[0013] In the actuator control system of the present disclosure, it is preferable that the holding unit includes a plurality of contact detection units, and the control unit selects detection signals from one or more of the plurality of contact detection units to determine whether there is abnormal contact or whether the object is being held properly. By adopting such a configuration, the circumferential and height positions of the pressing force applied to the holding unit 18 can be recognized more accurately, thereby making it possible to more accurately determine whether there is abnormal contact or whether the object is being held properly. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to prevent excessive force from being applied to a fluid pressure actuator and damage to an object. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a front view of a fluid pressure actuator according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a partially exploded perspective view of the fluid pressure actuator shown in FIG. 1. [Figure 3A] 2 is a partial cross-sectional view taken along the axial direction of the fluid pressure actuator including the base-end sealing portion shown in FIG. 1. FIG. [Figure 3B] FIG. 3B is a detailed view of part B in FIG. 3A. [Figure 4A] 2 is a partial cross-sectional view taken along the axial direction of the fluid pressure actuator including the tip-end sealing portion shown in FIG. 1. FIG. [Figure 4B]FIG. 4B is a detailed view of part C in FIG. 4A. [Figure 5] 2 is a cross-sectional view taken along the AA' cross section in the radial direction of the fluid pressure actuator in FIG. 1. FIG. [Figure 6] 10 is a diagram showing a state in which a fluid pressure is applied to the fluid pressure actuator to cause bending deformation and hold an object. FIG. [Figure 7] FIG. 2 is a schematic diagram showing an example of the configuration of a system using the fluid pressure actuator shown in FIG. [Figure 8A] 10 is a diagram showing a state in which a flexible printed circuit board that transmits a detection signal from a contact detection unit is provided along a restraining member. FIG. [Figure 8B] 10 is a diagram showing a state in which a conductive layer that transmits a detection signal from a contact detection unit is provided as an intermediate layer of a restraint member. FIG. [Figure 9] FIG. 2 is a block diagram showing the configuration of a control system of the fluid pressure actuator. [Figure 10] 10 is a diagram illustrating a modified example of a contact detection unit included in a holding member in a fluid pressure actuator according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of a fluid pressure actuator 1 according to the present disclosure will be described below with reference to the drawings. The same components are designated by the same reference numerals in each drawing. However, please note that the drawings are schematic and the dimensional ratios may differ from those of the actual components.

[0017] (Configuration of fluid pressure actuator 1) Fig. 1 shows a fluid pressure actuator 1 according to one embodiment of the present disclosure. As shown in Fig. 1 and Fig. 2, the fluid pressure actuator 1 includes a tube 11, a sleeve 12, a first sealing portion 13A, a second sealing portion 13B, a restraining member 17, and a holding portion 18.

[0018] In this embodiment, the central axis of the fluid pressure actuator 1 is disposed on the axis C. In this embodiment, the side of the holding part 18 (right side in FIG. 1) along this axis C is the tip side, and the side of the support part 40 (left side in FIG. 1) along this axis C is the base side. In addition, the direction perpendicular to the axis C is called the radial direction, and the direction away from the axis C along a straight line perpendicular to the axis C is called the radial outward direction, and the direction approaching the axis C along a straight line perpendicular to the axis C is called the radial inward direction. In addition, in the drawings, the "axial direction" is referred to as the D AX and "radial direction" is D R It is shown as follows.

[0019] In this embodiment, the holding portion 18 is a portion that comes into contact with the object O to be held by driving the fluid pressure actuator 1, and applies the driving force of the fluid pressure actuator 1 to the object O. The holding portion 18 has a substantially hemispherical tip portion 18t at the tip side of a cylindrical main body portion 18s when viewed from the front as shown in Fig. 1, and is attached to the sealing member 14 by fitting a connecting portion 14C shown by a dashed line into the inside of an attachment recess 18a (see Fig. 4A).

[0020] In this embodiment, the holding portion 18 may be formed of a conductive elastic material. The conductive elastic material is, for example, a composite material such as rubber or a resin elastomer compounded (dispersed and mixed) with a conductive filler such as carbon. The material of the holding portion 18 may be, for example, a material compounded with a conductive filler such as natural rubber, chloroprene rubber, ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber, or silicone rubber. However, when contact detection is performed by a method other than detecting a change in the resistance value of the holding portion 18, as described below, the holding portion 18 does not necessarily need to be a conductive elastic material, and other rubbers or resin elastomers that are not conductive may also be used.

[0021] In particular, it is preferable that at least the portion of holding portion 18 that comes into contact with the held object O be formed of an elastic material. With this configuration, holding portion 18 can hold object O without damaging it.

[0022] 1 and the like, and may be configured to have claws oriented toward the object O to be held, so that the claws come into stronger contact with the object O than other parts, increasing the static frictional force with the object O and more securely holding the object O. Also, the holding portion 18 may be configured to hold the object O by wrapping the palm of the hand around it, by providing a holding recess that is recessed in a direction away from the object O.

[0023] The holding portion 18 can be formed as a single unit by, for example, compression molding, injection molding, or extrusion molding. Furthermore, by using two-color molding, insert molding, or the like, the holding portion 18 can be optimized by using different materials for each portion. For example, one of the rubber materials described above may be used for the portion of the holding portion 18 that contacts the object O, and plastic, metal, or other materials may be used for other portions to increase rigidity.

[0024] Fluid can be introduced into the tube 11 of the fluid pressure actuator 1 through the connection port 14D provided in the first sealing portion 13A. When fluid flows into the tube 11, the fluid pressure actuator 1 contracts in the axial direction of the fluid pressure actuator 1 and expands in the radial direction. On the other hand, when fluid flows out of the tube 11, the fluid pressure actuator 1 expands in the axial direction of the fluid pressure actuator 1 and contracts in the radial direction. In this way, the fluid pressure actuator 1 can function as an actuator by changing its shape.

[0025] Such a fluid pressure actuator 1 is of the so-called McKibben type and can be used as an artificial muscle, as well as for the limbs, hands, or fingers of a robot that requires higher capabilities (contractile force).

[0026] The fluid used to drive the fluid pressure actuator 1 can be either a gas such as air, or a liquid such as water or mineral oil, but the fluid pressure actuator 1 in particular has high durability that can withstand hydraulic drive under high pressure.

[0027] The tube 11 is a cylindrical body that expands and contracts due to the pressure of the fluid. The tube 11 is made of an elastic material such as butyl rubber in order to repeatedly expand and contract due to the fluid. However, when the fluid pressure actuator 1 is hydraulically driven, the elastic member that makes up the tube 11 may be at least one selected from the group consisting of highly oil-resistant NBR (nitrile rubber), hydrogenated NBR, chloroprene rubber, and epichlorohydrin rubber.

[0028] The sleeve 12 is cylindrical and covers the outer surface of the tube 11. The sleeve 12 is an elastic structure made by weaving fiber cords oriented in a predetermined direction, and the oriented cords cross to form a repeated diamond shape. Due to this shape, the sleeve 12 undergoes pantograph deformation, restricting the axial expansion of the tube 11 while allowing radial expansion, and follows the deformation of the tube 11.

[0029] It is preferable to use fiber cords such as aromatic polyamide (aramid fiber) or polyethylene terephthalate (PET) as the fiber cords constituting the sleeve 12. However, the fiber cords constituting the sleeve 12 are not limited to these types of fiber cords, and may be, for example, high-strength fiber cords such as PBO fiber (polyparaphenylene benzobisoxazole).

[0030] The first sealing portion 13A and the second sealing portion 13B respectively seal the ends (tip end side and base end side) of the tube 11 in the axial direction. In this embodiment, the first sealing portion 13A seals the base end side (left side in FIG. 1) of the tube 11 in the axial direction, and the second sealing portion 13B seals the tip end side (right side in FIG. 1) of the tube 11 in the axial direction. In the present disclosure, the first sealing portion 13A and the second sealing portion 13B are collectively referred to simply as "sealing portion 13" unless otherwise distinguished.

[0031] As shown in FIG. 2, the sealing portion 13 (first sealing portion 13A in the illustrated example) includes a sealing member 14, a locking ring 15, and a crimping member 16.

[0032] The sealing member 14 seals the axial end of the tube 11. As shown in Fig. 2, the sealing member 14 has a head 14A and a body 14B extending axially from the head 14A. The body 14B is inserted into the tube 11 from the outside in the axial direction of the tube 11. In addition to the head 14A and the body 14B, the sealing member 14 may be provided with a connecting portion 14C for connecting another member.

[0033] The connecting portion 14C protrudes from the head portion 14A axially opposite to the body portion 14B. A radially extending through-hole may be defined in the connecting portion 14C to facilitate connection of other members. Referring to FIG. 1, in this embodiment, a support portion 40 that supports the fluid pressure actuator 1 is attached to the connecting portion 14C of the first sealing portion 13A. Furthermore, as shown in FIG. 1 and other figures, a holding portion 18 is attached to the connecting portion 14C of the second sealing portion 13B. The holding portion 18 is detachably attached to the fluid pressure actuator 1 by fitting the connecting portion 14C of the second sealing portion 13B into an attachment recess 18a (see FIG. 4A).

[0034] The sealing member 14 is made of a metal such as stainless steel, but is not limited to such a metal and may be made of a hard plastic material or the like.

[0035] 2 and 3A, the locking ring 15 is a ring-shaped member that locks the sleeve 12 to the sealing member 14. Specifically, as shown in Fig. 3A, the sleeve 12 is folded back radially outward via the locking ring 15.

[0036] 2, the locking ring 15 has a notch 15A cut out from a portion thereof so as to be able to engage with the sealing member 14. The locking ring 15 may be made of the same material as the sealing member 14, such as metal or hard plastic material, or may be made of a material such as natural fiber (natural fiber thread) or rubber (for example, an O-ring).

[0037] The crimping member 16 crimps the tube 11 and the sleeve 12 together with the sealing member 14. The crimping member 16 is a cylindrical member that is larger in outer diameter than the body portion 14B of the sealing member 14. The crimping member 16 is provided so as to cover the radial outside of the portion of the tube 11 and the sleeve 12 into which the sealing member 14 is inserted, and is crimped with a jig to fasten the tube 11 and the sleeve 12 together and fix them in close contact with the sealing member 14.

[0038] The crimping member 16 may be made of a metal such as an aluminum alloy, brass, or iron. As shown in Fig. 1, an indentation 16A, which is a mark made by crimping with a jig, may be formed on the outer circumferential surface of the crimping member 16.

[0039] The first sealing portion 13A differs from the second sealing portion 13B in that the sealing member 14 of the first sealing portion 13A is provided with a connection port 14D, a passing hole 14E, and a wire guide groove 14H (see FIGS. 3A and 3B), whereas the second sealing portion 13B is provided with a wire guide groove 14J and a wire guide hole 14F (see FIGS. 4A and 4B). As shown in FIG. 3A, in this embodiment, the sealing member 14 of the first sealing portion 13A is provided with the connection port 14D, the passing hole 14E, and the wire guide groove 14H. Furthermore, as shown in FIG. 4A, the sealing member 14 of the second sealing portion 13B is provided with the wire guide groove 14J and the wire guide hole 14F.

[0040] A hose (pipe) connected to a drive pressure source for the fluid pressure actuator 1, specifically a compressor for gas or liquid, is attached to the connection port 14D. The fluid that flows in via the connection port 14D passes through a passage hole 14E defined inside the sealing member 14 and flows into the inside of the tube 11. In this embodiment, the connection port 14D is provided so as to open toward the radially outer side of the head portion 14A of the sealing member 14. The passage hole 14E is formed across the head portion 14A and the body portion 14B. The connection port 14D and the inside of the tube 11 are in communication with each other via the passage hole 14E.

[0041] As shown in FIGS. 3A and 3B, the wire guide groove 14H of the first sealing portion 13A is a groove cut radially inward at a circumferential position where the restraining member 17 (described later) is attached. A wiring member 17a extends along the inside of the sleeve 12 from the distal end to the proximal end along the restraining member 17 and transmits a detection signal from a contact detection unit 120 (see FIG. 4A) provided at the distal end. As shown in FIGS. 3A and 3B, the wiring member 17a leaves the restraining member 17, enters the wire guide groove 14H, extends to the proximal end to a position adjacent to the connection port 14D, is then bent approximately 90 degrees radially outward, and extends to the outside of the fluid pressure actuator 1. As a result, as shown in FIG. 9 (control system 200 for the fluid pressure actuator 1), a contact detection signal from the contact detection unit 120 is transmitted via the wiring member 17a to a control unit 110 outside the fluid pressure actuator 1.

[0042] 4A and 4B, the wiring guiding groove 14J of the second sealing portion 13B is a groove portion cut out radially inward at a circumferential position where the restraining member 17 is attached. As shown in FIGS. 4A and 4B, the wiring member 17a leaves the restraining member 17 and enters the wiring guiding groove 14J, and further extends into the holding portion 18 through a wiring guiding hole 14F that extends in the direction of the axis C at an approximately radial center position. As shown in FIG. 8A, the wiring member 17a has two conductor patterns 17a1 and 17a2 that branch within the holding portion 18 and are electrically connected to different locations within the holding portion 18 to detect the resistance value of the holding portion 18.

[0043] The tip ends of two conductor patterns 17a1 and 17a2 extending from wiring member 17a are electrically connected and fixed to the tip end of mounting recess 18a via side recess 18b and wiring groove 18C of holding portion 18, respectively, using a conductive adhesive or the like. In this case, the tip ends of two conductor patterns 17a1 and 17a2 are respectively accompanied by half of base layer 17a3 and cover layer 17a4 shown in FIG. 8A. This configuration ensures reliable electrical connection between the tip end of wiring member 17a and holding portion 18.

[0044] 2 to 6, a restraining member 17 is provided on the radially inner side of the sleeve 12. The restraining member 17 is provided on the radially inner side of the sleeve 12, ranging from the base end side to the tip end side in the axial direction.

[0045] The restraint member 17 is not compressed in the axial direction but is deformable only along the radial direction (also referred to as the bending direction). In other words, the restraint member 17 resists compression along the axial direction at a predetermined position in the circumferential direction of the tube 11 and is bendable and deformable in a direction perpendicular to the axial direction (radial direction).

[0046] The restraining member 17 also has the function of restraining (restricting) the expansion of the tube 11 (and the sleeve 12) radially outward at a predetermined position in the circumferential direction of the tube 11 where the restraining member 17 is provided.

[0047] The restraining member 17 is formed using, for example, a leaf spring. The dimensions of the leaf spring are not particularly limited and may be selected depending on the size of the fluid pressure actuator 1, the required force to be generated, and the like. The material of the leaf spring is also not particularly limited, but typically, it is sufficient if it is a material that is easy to bend and resistant to compression, such as a metal such as stainless steel. For example, the restraining member 17 may be formed from a thin plate of carbon fiber reinforced plastic (CFRP). CFRP is less susceptible to plastic deformation than metal, and therefore the fluid pressure actuator 1 can easily return to its original straight state after being bent.

[0048] 3A to 6, the restraining member 17 is provided between the tube 11 and the sleeve 12. FIG. 5 is a cross-sectional view taken along the line A-A' in FIG. 1, taken along the radial direction of the fluid pressure actuator 1. The restraining member 17 may be in close contact with the tube 11 and the sleeve 12, or some gaps may be formed between the restraining member 17 and the tube 11 and / or the sleeve 12, and on the sides of the restraining member 17. However, the restraining member 17 may be embedded in the tube 11, or may be provided radially inward of the tube 11.

[0049] The restraining member 17 is provided on a portion of the tube 11 (and sleeve 12) in the circumferential direction. That is, the tube 11 has a portion in the circumferential direction that is covered by the restraining member 17 and a portion that is not covered by the restraining member 17. The width of the restraining member 17 is not particularly limited, but may be approximately half the outer diameter of the tube 11 as a reference.

[0050] In this embodiment, the restraining member 17 is flat, but may be curved slightly to fit the cross-sectional shapes of the tube 11 and the sleeve 12 as long as it does not affect the way it bends.

[0051] The restraining member 17 is provided from the base end side to the tip end side in the axial direction of the tube 11 and the sleeve 12. Specifically, the restraining member 17 may be provided from the first sealing portion 13A to the second sealing portion 13B. In this embodiment, the restraining member 17 has a length substantially equal to that of the tube 11.

[0052] However, the restraining member 17 does not necessarily have to be provided completely from the first sealing portion 13A to the second sealing portion 13B, and the restraining member 17 does not have to extend to either the first sealing portion 13A or the second sealing portion 13B (especially the second sealing portion 13B side which is likely to become a free end when bent).

[0053] 3A to 6, in this embodiment, a wiring member 17a is arranged radially inside the restraint member 17. The wiring member 17a extends from the distal end to the proximal end along the restraint member 17, and electrically connects the holding portion 18 (contact detection portion 120) made of a conductive rubber member to a control system 200 (see FIG. 9) arranged outside the fluid pressure actuator 1.

[0054] Wiring member 17a is disposed along restraint member 17 on the radially inner side thereof, and has a layer configuration as shown in Fig. 8A. That is, wiring member 17a includes base layer 17a3, two conductor patterns 17a1 and 17a2 provided on the radially inner surface of base layer 17a3, and cover layer 17a4 covering two conductor patterns 17a1 and 17a2.

[0055] The wiring member 17a may be, for example, a flexible printed circuit (FPC). In this case, the base layer 17a3 and the cover layer 17a4 may be made of, for example, a polyimide resin having heat resistance and a predetermined strength. The base layer 17a3 and the cover layer 17a4 may also be made of polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, or liquid crystal polymer. The wiring member 17a may be adhesively fixed to the restraining member 17 by an adhesive layer, or may be fixed by having both longitudinal ends thereof sandwiched between the tube 11 and the sleeve 12 by the crimping members 16.

[0056] In this embodiment, two conductor patterns 17a1 and 17a2 are arranged on the same surface, but three or more may be arranged on the same surface, or multiple conductor layers may be provided with insulating layers such as polyimide layers sandwiched between them. Also, wiring members 17a may be arranged on both sides of restraint member 17.

[0057] 8B, the wiring member 17a may be provided as an intermediate layer of the restraint member 17 between the outer plate 17b1 and the inner plate 17b2 that constitute the restraint member 17. If the outer plate 17b1 and the inner plate 17b2 are made of an insulator or are insulated, the base layer 17a3 and the cover layer 17a4 may not necessarily be provided.

[0058] In this embodiment, the holding unit 18 is connected to an external constant current source 150 via the wiring member 17a. A potential difference generated between the two conductor patterns 17a1 and 17a2 of the wiring member 17a connected to the holding unit 18 by passing a constant current through the holding unit 18 (contact detection unit 120) corresponds to the resistance value between the two conductor patterns 17a1 and 17a2, and the control unit 110 (see FIG. 9) acquires this change in resistance value as the contact detection result.

[0059] Each process in the control unit 110 can be realized as software processing by, for example, causing a predetermined program stored in a storage unit (not shown) or the like to be executed by a CPU (Central Processing Unit) or DSP (Digital Signal Processor) included in the control unit 110. However, this is not limiting, and each process may be configured to be realized as hardware processing by, for example, an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The control unit 110 may acquire the above potential difference via an AD converter.

[0060] The storage unit that stores the predetermined program includes a readable storage medium, and the storage medium includes a rewritable and programmable ROM such as an EPROM, EEPROM, or flash memory, or other tangible storage medium such as a magnetic disk storage medium that can store information, or any combination thereof. The storage unit may be provided within the control unit 110, or may be a storage medium in an external storage device that can be connected to the control unit 110. The storage unit may store various data acquired by the control unit 110 in addition to the control program.

[0061] The fluid pressure actuator 1 and the control unit 110 constitute an actuator control system.

[0062] (Fluid pressure actuator operation) Next, the operation of the fluid pressure actuator 1 according to one embodiment of the present disclosure will be described with reference to Fig. 6. In Fig. 6, the base end side of the fluid pressure actuator 1 is fixed by a support part 40, and the tip side is free to move. In other words, the base end side of the fluid pressure actuator 1 is the fixed end, and the tip side is the free end.

[0063] 1, the holding portion 18 is attached by fitting the connecting portion 14C on the tip side (lower side in FIG. 6) of the fluid pressure actuator 1 into the attachment recess 18a of the holding portion 18.

[0064] 6 shows only one fluid pressure actuator 1. However, as shown in FIG. 7, for example, a plurality of fluid pressure actuators 1 may be arranged side by side in the circumferential direction.

[0065] 9 transmits a target pressure signal corresponding to the pressing force to be applied to the object O to an electro-pneumatic (E / P) converter 130. The E / P converter 130 adjusts the pressure of the pressurized air supplied from an air source 140 in accordance with the target pressure signal and supplies it into the tube 11 of the fluid pressure actuator 1. When fluid flows into the inside of the tube 11 of the fluid pressure actuator 1, the tube 11 attempts to contract in the axial direction, but because a restraining member 17 is provided along the axial direction at a portion of the circumference of the tube 11, the contraction of the tube 11 along the axial direction is restrained (restricted) at the circumferential portion of the tube 11 where the restraining member 17 is provided (the portion to the left of the axis C in FIG. 6). On the other hand, the portion of the tube 11 where the restraining member 17 is not provided (the portion to the right of the axis C in FIG. 6) tends to contract, so that the restraining member 17 acts like a backbone, and the fluid pressure actuator 1 (specifically, the tube 11 and sleeve 12) bends in direction D1 on the opposite side of the circumferential position of the tube 11 (the right side in FIG. 6) from the position where the restraining member 17 is provided. Direction D1 is also referred to as the bending direction.

[0066] On the other hand, when the fluid flows out from inside the fluid pressure actuator 1, the fluid pressure actuator 1 returns to its original linear posture. This allows the fluid pressure actuator 1 to be used as, for example, a robot arm or the fingers of a robot hand.

[0067] For example, as shown in FIG. 6, when the fluid pressure actuator 1 is driven to displace the holding portion 18 in the direction D1, it can cooperate with other fluid pressure actuators 1 not shown in FIG. 6 to clamp and lift an object O placed on a workbench T.

[0068] 4A, the holding portion 18 includes a contact detection unit 120. That is, two conductor patterns 17a1 and 17a2 of the wiring member 17a are fixed with a conductive adhesive to the tip of the mounting recess 18a in the holding portion 18 formed of a conductive rubber member and to a lateral recess 18b recessed radially outward from the mounting recess 18a, making it possible to measure the resistance value between these two points in the holding portion 18.

[0069] 4A, when the side surface of the main body of the holding unit 18 (the region designated by the reference symbol 18s) comes into contact with the object O, the conductive rubber member between the bonded portions of the two conductor patterns 17a1 and 17a2 is compressed in the radial direction (the vertical direction in FIG. 4A), causing a change in the resistance value between the two points. The control unit 110 may be configured to calculate the pressure applied to the holding unit 18 from this change in resistance value. That is, the larger the change in resistance value, the larger the calculated pressure applied to the holding unit 18.

[0070] In this case, a large change in resistance value means, for example, that the ratio of the absolute value of the change in resistance value to the resistance value before the change is large.

[0071] For example, if the calculated pressing force is greater than a first threshold, the control unit 110 can determine that an excessive pressing force has been applied by the holding unit 18 to the object O or that abnormal contact has occurred in which the holding unit 18 has come into contact with an object other than the object O, and can stop driving the fluid pressure actuator 1. Furthermore, for example, if the calculated pressing force is greater than or equal to a second threshold and less than or equal to the first threshold, the control unit 110 can determine that the object O is being held normally.

[0072] In this case, the first threshold value is preferably set to a pressing force (for example, five times or more the expected pressing force) that is clearly greater than the pressing force that acts on holding unit 18 when holding an expected object O. If the pressing force acting on holding unit 18 exceeds this first threshold value, it is highly likely that holding unit 18 has come into contact with an obstacle other than the expected object O, a container, a floor, a wall, or the like, and is receiving pressing force, and it may be determined that abnormal contact has occurred.

[0073] Furthermore, the second threshold value is preferably set to the minimum value of pressing force that is considered appropriate in consideration of the weight of the expected object O and the number of fluid pressure actuators 1 to be used.

[0074] Furthermore, when the control unit 110 cannot acquire an appropriate resistance value, it can recognize that a break has occurred in the path from the holding unit 18 to the control unit 110.

[0075] A user of the fluid pressure actuator 1 can easily replace the holding part 18 with an appropriate one that is optimal for the size, weight, surface condition, or placement location of the object O. For example, if the object O is heavy, the holding part 18 can be replaced with one made of a more rigid material, or if the object O is large, the holding part 18 can be replaced with one having a larger holding area.

[0076] In this embodiment, only two (one set) of conductor patterns 17a1 and 17a2 from wiring member 17a are arranged inside holding portion 18, but this is not limiting. For example, two or more sets of conductor patterns may be arranged in different locations inside holding portion 18, and a change in resistance value at multiple locations inside holding portion 18 may be detected.

[0077] In this case, the holding unit 18 is equipped with multiple contact detection units 120, and the control unit 110 can select the detection signal from one or more of the multiple contact detection units 120 to determine whether there is abnormal contact or whether the object O is being held normally.

[0078] Furthermore, the control unit 110 may be configured to use detection signals from a plurality of contact detection units 120 to determine the circumferential position, height position, etc. at which the contact is pressed.

[0079] For example, a trained model for contact detection that learns the relationship between the magnitude, circumferential position, and height position of the pressure applied to the holding unit 18 and the detection signals from the multiple contact detection units 120 provided in the holding unit 18 may be generated in advance and stored in a memory unit, and the control unit 110 may estimate the magnitude, circumferential position, height position, etc. of the pressure applied to the holding unit 18 using the newly output detection signals from the multiple contact detection units 120 and the trained model.

[0080] (System using fluid pressure actuator) An example of the configuration of a system using the fluid pressure actuator 1 will be described with reference to Fig. 7. Specifically, the system shown in Fig. 7 is a gripping system 50 that grips an object O by driving the fluid pressure actuator 1.

[0081] As shown in FIG. 7, the gripping system 50 includes a base portion 51, a support portion 52, a first actuator connection portion 53, a telescopic actuator 54, a second actuator connection portion 55, and a fluid pressure actuator 1.

[0082] A support column 52 is erected on the upper surface of the base 51. The upper end of the support column 52 is folded downward, and a first actuator connection section 53 is connected to the tip of the support column 52.

[0083] A telescopic actuator 54 is suspended from the first actuator connection part 53. The telescopic actuator 54 adjusts the vertical position of the fluid pressure actuator 1. The telescopic actuator 54 does not have a restraining member 17 like the fluid pressure actuator 1 described above, and may be a general McKibben type actuator. Therefore, the telescopic actuator 54 contracts and expands along the axial direction (the direction of the white arrow in the figure). In other words, the telescopic actuator 54 simply changes its length in the axial direction, and cannot bend like the fluid pressure actuator 1 having the restraining member 17 described above. However, the telescopic actuator 54 may be provided with the restraining member 17 and be able to bend. Furthermore, the telescopic actuator 54 is not limited to a McKibben type actuator, and may be an actuator of another configuration.

[0084] A second actuator connection part 55 is connected to the lower end of the telescopic actuator 54. The fluid pressure actuator 1 is suspended from the second actuator connection part 55 via the support part 40.

[0085] In the illustrated example, there are provided four fluid pressure actuators 1 and one support part 40 that supports the base end sides of the four fluid pressure actuators 1. Each of the four fluid pressure actuators 1 is provided with a restraining member 17 extending along the axial direction of the tube 11.

[0086] In the illustrated example, each of the four fluid pressure actuators 1 is provided with a restraint member 17 on the side opposite to the opposing fluid pressure actuator 1. With this configuration, each of the four fluid pressure actuators 1 can bend and deform in the direction of the opposing fluid pressure actuator 1.

[0087] As a result, the gripping system 50 can grip and lift the object O by driving the telescopic actuator 54 and the fluid pressure actuator 1.

[0088] That is, the control unit 110 that controls the gripping system 50 controls the pressure inside the four fluid pressure actuators 1, causing the holding units 18 attached to the tip of each fluid pressure actuator 1 to bend and deform in a direction that brings them closer to each other, thereby holding the object O.

[0089] The control unit 110 may change the number of fluid pressure actuators 1 to be driven, or may adjust the driving pressure and height position of the base end of the fluid pressure actuators 1 as appropriate, depending on the size, weight, etc. of the object O to be held. Furthermore, by making the spacing between the multiple fluid pressure actuators 1 further adjustable, the object O may be held at an optimal position depending on the size, etc. of the object O.

[0090] The control unit 110 that controls the gripping system 50 may determine that an abnormal contact has occurred in which the holding unit 18 has applied excessive pressure to the object O or has come into contact with an object other than the object O, for example, when the pressing force calculated in at least one of the multiple fluid pressure actuators 1 is greater than a first threshold value, and may stop operation of the gripping system 50.

[0091] In addition, the control unit 110 of the gripping system 50 may determine that the object O is being held normally, for example, when the pressing force calculated in two of the multiple fluid pressure actuators 1 is greater than a second threshold and less than a first threshold.

[0092] (Modification of the holding part) Next, a modified example of the holding portion 18 attached to the fluid pressure actuator 1 will be described with reference to FIG.

[0093] The holding portion 18 is a portion that comes into contact with the object O to be held by driving the fluid pressure actuator 1, and applies the driving force of the fluid pressure actuator 1 to the object O. The holding portion 18 has a substantially hemispherical tip portion 18t at the tip side of a cylindrical main body portion 18s, and is attached to the sealing member 14 by fitting the connecting portion 14C into the inside of the attachment recess 18a.

[0094] In this embodiment, the holding portion 18 may be formed of an elastic material. The material of the holding portion 18 may be, for example, silicone rubber, urethane rubber, chloroprene rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, fluororubber, natural rubber, or other elastic materials. The holding portion 18 may also be formed of other rubbers, resin elastomers, or the like.

[0095] In particular, it is preferable that at least the portion of holding portion 18 that comes into contact with the held object O be formed of an elastic material. With this configuration, holding portion 18 can hold object O without damaging it.

[0096] The holding portion 18 can be formed as a single unit by, for example, compression molding, injection molding, or extrusion molding. Furthermore, by using two-color molding, insert molding, or the like, the holding portion 18 can be optimized by using different materials for each portion. For example, one of the rubber materials described above may be used for the portion of the holding portion 18 that contacts the object O, and plastic, metal, or other materials may be used for other portions to increase rigidity.

[0097] A wire-passing groove 18C recessed radially outward is provided at a circumferential position on a part of the side surface of the mounting recess 18a. The wire-passing groove 18C extends axially toward the tip, and the tip end of the wire-passing groove 18C is cut out with a width equal to the radial width of the mounting recess 18a. As shown in Fig. 10, a piezoelectric element 19 functioning as a contact detection unit 120 is arranged at the tip end of the wire-passing groove 18C in a state capable of detecting pressure in the radial direction (the up and down direction in Fig. 10).

[0098] When a force is applied to the piezoelectric element 19 and the piezoelectric element 19 is deformed, the piezoelectric element 19 generates an electromotive force. When pressure is applied in the radial direction in FIG. 10, an electromotive force corresponding to the magnitude of the pressure is generated between the two conductor patterns 17a1 and 17a2. The control unit 110 (see FIG. 9) acquires this electromotive force as a contact detection result.

[0099] In this embodiment, the piezoelectric element 19 is arranged to detect pressure in the radial direction, but the piezoelectric element 19 is arranged taking into consideration the location and direction to which the pressure to be detected is applied. One or more piezoelectric elements 19 can be arranged in the holding part 18.

[0100] The contact detection unit 120 may use means other than the conductive rubber member or the piezoelectric element 19 as long as it can detect pressure following the elastic deformation of the holding unit 18. The contact detection unit 120 may use, for example, a strain gauge.

[0101] As described above, the fluid pressure actuator 1 according to one embodiment of the present disclosure is a fluid pressure actuator 1 driven by fluid pressure, and includes a cylindrical tube 11 that expands and contracts, a sleeve 12 that covers the outer surface of the tube 11 and restricts axial extension of the tube 11 while allowing radial extension, and a holding unit 18 that is attached to the axial tip of the tube 11 and holds an object O. At least the portion of the holding unit 18 that holds the object O is formed of an elastic material and includes a contact detection unit 120 that detects contact with an object. By adopting this configuration, the object O is held by an elastic material, thereby preventing damage or scratches to the object O. Furthermore, by including the contact detection unit 120 in the holding unit 18, abnormal contact, such as application of excessive pressure to the object O or contact with an object other than the object O, can be easily detected, thereby improving the controllability of the fluid pressure actuator 1. This also prevents damage to the fluid pressure actuator 1 and the object O.

[0102] Furthermore, in this embodiment, the fluid pressure actuator 1 further includes a restraining member 17 that restricts axial contraction of the tube 11, and the detection signal from the contact detection unit 120 is configured to be transmitted through or along the restraining member 17. By adopting such a configuration, the wiring member 17a can be arranged within or along the restraining member 17, which extends in the signal transmission direction within the fluid pressure actuator 1 and has a relatively high rigidity, so that a wiring path can be secured without adding any additional members other than the wiring member 17a. Furthermore, breakage of the wiring member 17a can be made less likely to occur.

[0103] In this embodiment, the restraining member 17 is configured as a laminated plate having, as an intermediate layer, a conductive layer that transmits a detection signal from the contact detection unit 120. By using the wiring member 17a as an intermediate layer of the restraining member 17 in this way, the wiring member 17a is protected by the outer layer of the restraining member 17, thereby improving the reliability of the wiring member 17a.

[0104] In this embodiment, the elastic member is a conductive member, and the contact detection unit 120 is configured to be able to detect contact with an object by detecting the resistance value of the elastic member. By adopting such a configuration, the holding unit 18 can be formed from a conductive member and used as a contact sensor, so that contact with the holding unit 18 can be detected without incorporating a new sensor.

[0105] In this embodiment, the contact detection unit 120 is configured to include a piezoelectric element 19. By adopting such a configuration, pressure in a predetermined direction at a predetermined position can be detected with a simple sensor, so that abnormal contact with a pressure force greater than a predetermined pressure can be reliably detected.

[0106] Furthermore, this embodiment is an actuator control system including any of the fluid pressure actuators 1 described above and a control unit 110 that controls the fluid pressure actuator 1, and the control unit 110 is configured to determine that abnormal contact has occurred when the pressing force on the holding unit 18 based on the detection signal from the contact detection unit 120 is greater than a first threshold. By adopting such a configuration, abnormal contact in which the holding unit 18 applies excessive pressing force to the object O or comes into contact with an object other than the object O can be recognized, and the drive of the fluid pressure actuator 1 can be quickly stopped. In this embodiment, forming the holding unit 18 from an elastic material can prevent damage or scratches to the object O, but it has previously been difficult to detect abnormal contact. However, by introducing the contact detection unit 120, abnormal contact can be quickly detected and the drive of the fluid pressure actuator 1 can be stopped.

[0107] Furthermore, in this embodiment, the control unit 110 is configured to acquire detection signals from the contact detection units 120 of the multiple fluid pressure actuators 1, and determine that the object O is being held properly when the pressing force on the holding unit 18 based on the detection signals from at least two fluid pressure actuators 1 is equal to or greater than the second threshold and equal to or less than the first threshold. By employing such a configuration, it is possible to determine that the object O is being held properly by recognizing that the fluid pressure actuator 1 is not applying an excessive pressing force and that the object O is being clamped by the multiple fluid pressure actuators 1 with an appropriate pressing force.

[0108] Furthermore, in this embodiment, the holding unit 18 is equipped with a plurality of contact detection units 120, and the control unit 110 is configured to select a detection signal from one or more of the plurality of contact detection units 120 to determine whether the object O is being held properly or abnormally. By employing such a configuration, the circumferential and height positions of the pressing force applied to the holding unit 18 can be recognized more accurately, and therefore, whether the object O is being held properly or abnormally can be determined more accurately.

[0109] Although the present disclosure has been described based on the drawings and embodiments, it should be noted that those skilled in the art can make various modifications and alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are within the scope of the present invention. For example, the configurations or functions included in each embodiment can be rearranged so as not to cause logical inconsistencies. Furthermore, the configurations or functions included in each embodiment can be used in combination with other embodiments, and multiple configurations or functions can be combined, divided, or partially omitted.

[0110] For example, the fluid pressure actuator 1 according to this embodiment is configured to include a holder 18 having the shape shown in Fig. 4A etc., but is not limited to this. The shape of the holder 18 can be various depending on the shape, size, weight, surface condition, etc. of the object O to be held. [Industrial Applicability]

[0111] The present disclosure relates to a fluid pressure actuator 1 and an actuator control system. [Explanation of symbols]

[0112] 1: fluid pressure actuator, 11: tube, 12: sleeve, 13: sealing portion, 13A: first sealing portion, 13B: second sealing portion, 14: sealing member, 14A: head portion, 14B: body portion, 14C: connecting portion, 14D: connection port, 14E: passage hole, 14F: wiring introduction hole, 14H: wiring introduction groove, 14J: wiring introduction groove, 15: locking ring, 15A: notch portion, 16: crimping member, 16A: indentation, 17: restraining member, 17a: wiring member, 17a1: conductor pattern, 17a2: conductor pattern, 17a3: base layer, 17a4: cover layer, 17b1: outer plate, 17b2: inner plate, 18: retaining portion, 18a: mounting recess, 18b: Lateral recess, 18C: Wiring groove, 18s: Main body, 18t: Tip, 19: Piezoelectric element, 40: Support, 50: Grip system, 51: Base, 52: Support, 53: First actuator connection, 54: Telescopic actuator, 55: Second actuator connection, 110: Control unit, 120: Contact detection unit, 130: E / P converter, 140: Air source, 150: Constant current source, 200: Control system, C: Axis, O: Object, T: Work table, D1: Deflection direction

Claims

1. A fluid pressure actuator driven by fluid pressure, a cylindrical tube that expands and contracts; a sleeve that covers an outer peripheral surface of the tube and restricts axial extension of the tube while allowing radial extension of the tube; a holding part attached to the axial tip side of the tube and holding an object; Equipped with At least a portion of the holding unit that holds the object is made of an elastic material, and the holding unit has a contact detection unit that detects contact with an object, the fluid pressure actuator further includes a restraining member that restricts axial contraction of the tube, A fluid pressure actuator, wherein the detection signal from the contact detection unit is transmitted through or along the restraint member.

2. 2. The fluid pressure actuator according to claim 1, wherein the restraining member is a laminated plate having a conductive layer as an intermediate layer for transmitting a detection signal from the contact detection portion.

3. the elastic member is a conductive member, 3. The fluid pressure actuator according to claim 1, wherein the contact detection section is capable of detecting contact of an object by detecting a resistance value of the elastic member.

4. The fluid pressure actuator according to claim 1 , wherein the contact detection unit includes a piezoelectric element.

5. 5. An actuator control system comprising: the fluid pressure actuator according to claim 1; and a control unit that controls the fluid pressure actuator, The control unit determines that an abnormal contact has occurred when the pressing force on the holding unit based on the detection signal from the contact detection unit is greater than a first threshold value.

6. 6. The actuator control system according to claim 5, wherein the control unit acquires detection signals from the contact detection units of the plurality of fluid pressure actuators, and determines that the object is being held normally when the pressing force on the holding unit based on the detection signals from at least two of the fluid pressure actuators is equal to or greater than a second threshold and equal to or less than the first threshold.

7. 7. The actuator control system according to claim 5, wherein the holding unit includes a plurality of contact detection units, and the control unit selects detection signals from one or more of the plurality of contact detection units to determine whether an abnormal contact has occurred or whether the object is being held normally.

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