Manipulator

Abstract

This manipulator is provided with: at least one flexible actuation body which includes a curved flexible part; a beam part which has one end connected to the flexible part; and a shaft part to which the other end of the beam part is connected. The flexible actuation body is configured to be operable in a non-sliding manner with respect to the beam part and the shaft part.

Description

manipulator

[0001] The present invention relates to a manipulator. This invention claims priority to U.S. Provisional Application No. 63 / 537,203, filed in the United States on September 8, 2023, the contents of which are incorporated herein by reference.

[0002] In recent years, surgical support robots have been increasingly introduced to reduce the burden on surgeons during minimally invasive surgery. Multi-degree-of-freedom robotic forceps equipped on surgical support robots have been proposed, including those with power transmission mechanisms such as wire pulley mechanisms, gear mechanisms, and link mechanisms. Prior art related to multi-degree-of-freedom manipulators is disclosed, for example, in Patent Document 1. Patent Document 1 proposes a manipulator having a flexible actuator that deforms a leaf spring by pushing or pulling it, thereby operating an actuator with multiple degrees of freedom. This flexible actuator includes a rectangular horizontal leaf spring, a curved vertical leaf spring that stands upright and has a plate surface perpendicular to the plate surface of the horizontal leaf spring, its base end connected to one longitudinal end of the horizontal leaf spring, protruding to one side in the plate width direction of the horizontal leaf spring and extending along the longitudinal direction of the horizontal leaf spring, with its tip in the extending direction forming a bent part that bends in the direction opposite to the protruding direction, a shaft connected to the tip of the bent part and supported by a rotation center perpendicular to the plate surface of the horizontal leaf spring so as to be able to rotate freely, and an actuator that is provided on the outer periphery of the shaft so as to protrude outside the rotation radius.

[0003] International Publication No. 2017 / 057761

[0004] However, in the manipulator disclosed in Patent Document 1, there is a risk of wear occurring due to parts rubbing against each other.

[0005] Therefore, an object of the present invention is to suppress wear.

[0006] To solve the above problems, an aspect of the present disclosure has the following configuration: (1) A manipulator according to an aspect of the present disclosure includes at least one flexible actuator including a curved flexible portion, a beam portion having one end connected to the flexible portion, and a shaft portion having the other end connected to the beam portion, and the flexible actuator is configured to be operable without sliding relative to the beam portion and the shaft portion.

[0007] (2) In the manipulator described in (1) above, the flexible actuation body, the beam portion, and the shaft portion may be integrally formed from the same member.

[0008] (3) In the manipulator described in (2) above, the identical member may be formed of a polymer material.

[0009] (4) In the manipulator described in any one of (1) to (3) above, the at least one flexible actuator may include two flexible actuators consisting of a first flexible actuator arranged at an interval on one side of the shaft in the radial direction, and a second flexible actuator arranged at an interval on the other side of the shaft in the radial direction.

[0010] (5) In the manipulator described in (4) above, at least the flexible portions of the two flexible actuating bodies may be arranged with an interval in the axial direction of the shaft portion.

[0011] According to the above aspect, wear can be suppressed.

[0012] 1. A perspective view of a manipulator according to an embodiment. 2. A perspective view showing a bending operation of the manipulator according to an embodiment. 3. A perspective view showing an opening and closing operation of the manipulator according to an embodiment. 4. A plan view taken along arrow IV in FIG. 1. 5. A side view taken along arrow V in FIG. 1. 6. A plan view taken along arrow VI in FIG. 1. 7. A side view taken along arrow VII in FIG. 1. 8. A side view taken along arrow VIII in FIG. 1. 9. A side view taken along arrow IX in FIG. 1. 10. A diagram showing the results of finite element analysis of an example. 11. A diagram showing the appearance of an experimental device according to an example. 12. A diagram showing the results of video analysis of an example.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, a manipulator that applies a compliant mechanism and constitutes a robotic forceps to be mounted on a surgical support robot will be described as an example of a manipulator. A compliant mechanism refers to a mechanism that uses flexible elements to convert motion forms (a mechanism that transmits force or movement using elastic deformation). This manipulator is used, for example, in laparoscopic surgery, a minimally invasive surgical technique.

[0014] In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," do not only mean such arrangements or states in the strict sense, but also include arrangements or states in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. In the drawings used in the following description, the scale of each component may be changed as appropriate to make each component recognizable.

[0015] <Manipulator> Fig. 1 is a perspective view of a manipulator 1 according to an embodiment. Fig. 2 is a perspective view showing a bending operation of the manipulator 1 according to an embodiment. Fig. 3 is a perspective view showing an opening and closing operation of the manipulator 1 according to an embodiment. Referring to Figs. 1 to 3 together, the manipulator 1 includes at least one flexible actuating body 2A, 2B including curved flexible portions 21A, 21B, beam portions 3A, 3B having one ends connected to the flexible portions 21A, 21B, and a shaft portion 4 having the other ends connected to the beam portions 3A, 3B.

[0016] The manipulator 1 includes mechanism end portions 5A and 5B connected to actuators (not shown) such as motors. Two mechanism end portions 5A and 5B are provided, spaced apart in the axial direction of the shaft portion 4. Each of the mechanism end portions 5A and 5B is formed in a rectangular parallelepiped shape. The manipulator 1 is configured so that, by driving the actuators, the mechanism end portions 5A and 5B can be displaced in the axial longitudinal direction (the direction of the arrows shown in Figures 2 and 3).

[0017] <Flexible Actuators> The flexible actuating bodies 2A, 2B are configured to be non-slidably movable relative to the beams 3A, 3B and the shaft 4. The actuating sections 22A, 22B, including the distal ends of the flexible actuating bodies 2A, 2B (the ends opposite the mechanism terminals 5A, 5B in the longitudinal direction), constitute end effectors. The term "end effector" refers to the actual working part of a surgical instrument. Examples of end effectors include clamps, grasping devices, scissors, staplers, and needle holders.

[0018] The flexible actuating bodies 2A and 2B, the beams 3A and 3B, and the shaft 4 are integrally formed from the same member. The same member is made of a polymer material. An example of the polymer material is TPU (thermoplastic polyurethane elastomer).

[0019] Other polymeric materials include, for example, polyethylene, polypropylene, styrene-based resin, polyvinyl chloride, epoxy resin, acrylic resin, fluororesin, etc. As the polymeric material, it is preferable to use a material that is excellent in, for example, biocompatibility, a wide elastic range, and corrosion resistance. Note that the polymeric material is not limited to the above and can be changed according to the design specifications.

[0020] Fig. 4 is a plan view taken along arrow IV in Fig. 1. Fig. 5 is a side view taken along arrow V in Fig. 1. Fig. 6 is a plan view taken along arrow VI in Fig. 1. Fig. 7 is a side view taken along arrow VII in Fig. 1. Fig. 8 is a side view taken along arrow VIII in Fig. 1. Fig. 9 is a side view taken along arrow IX in Fig. 1. Referring to Figs. 4 to 9 together, the at least one flexible actuating body 2A, 2B includes two flexible actuating bodies 2A, 2B, each of which includes a first flexible actuating body 2A arranged on one side of the shaft portion 4 in a radial direction with a gap therebetween and a second flexible actuating body 2B arranged on the other side of the shaft portion 4 in a radial direction with a gap therebetween.

[0021] The first flexible actuating body 2A is composed of a first connecting portion 20A that extends to one side from one of the mechanism end portions 5A (hereinafter also referred to as the "first end portion 5A"), is arranged at a distance on one radial side of the shaft portion 4, and is formed in an L-shape in a planar view, a first flexible portion 21A that extends further toward the tip side from the tip side of the first connecting portion 20A (the side opposite the first end portion 5A in a planar view) and then is formed to be curved inward in an arc-like shape in a planar view, and a first actuating portion 22A (a portion that functions as one of the end effectors) that extends further toward the tip side from the tip side of the first flexible portion 21A and is formed to be tapered in a planar view (see Figure 4).

[0022] The second flexible actuator 2B is composed of a second connecting portion 20B extending from the other mechanism end portion 5B (hereinafter also referred to as the "second end portion 5B") to the other side, arranged at a distance on the other radial side of the shaft portion 4, and formed in an inverted L-shape in plan view (an L-shape opposite to that of the first connecting portion 20A), a second flexible portion 21B extending further toward the tip side from the tip side of the second connecting portion 20B (the side opposite the second end portion 5B in plan view) and then formed by curving inward in an arc shape, and a second operating portion 22B (a portion that functions as the other end effector) extending further toward the tip side from the tip side of the second flexible portion 21B and formed into a tapered shape in plan view (see Figure 6).

[0023] The two flexible actuating bodies 2A, 2B are arranged such that at least the flexible portions 21A, 21B of each are spaced apart in the axial direction of the shaft portion 4. In the two flexible actuating bodies 2A, 2B, it is preferable that the connecting portions 20A, 20B, the flexible portions 21A, 21B, and the actuating portions 22A, 22B of each are spaced apart in the axial direction of the shaft portion 4 (see FIGS. 5 and 7).

[0024] In the two flexible actuators 2A, 2B, each of the connecting portions 20A, 20B and each of the flexible portions 21A, 21B may have a uniform thickness in a direction perpendicular to the axial direction of the shaft portion 4 in a side view (see FIGS. 5 and 7). In the two flexible actuators 2A, 2B, each of the connecting portions 20A, 20B and each of the flexible portions 21A, 21B may be formed thinner than the thickness of the mechanism end portions 5A, 5B in a side view.

[0025] When the two flexible actuating bodies 2A, 2B are closed (the state shown in FIG. 1), the actuating portions 22A, 22B may include portions that overlap each other in a side view (see FIGS. 5 and 7). When the two flexible actuating bodies 2A, 2B are closed, the inner surfaces of the actuating portions 22A, 22B that face each other may be spaced apart (see FIG. 8).

[0026] <Beam Portion> When the two flexible actuating bodies 2A, 2B are closed, the beam portions 3A, 3B extend linearly in a planar view (see FIGS. 4 and 6). Two beam portions 3A, 3B are provided with an interval in the axial direction of the shaft portion 4. The two beam portions 3A, 3B consist of a first beam portion 3A, 3B having one end connected to the first flexible portion 21A and a second beam portion 3A, 3B having one end connected to the second flexible portion 21B. When the two flexible actuating bodies 2A, 2B are closed, the first beam portions 3A, 3B and the second beam portions 3A, 3B overlap each other in a planar view.

[0027] <Shaft> One shaft 4 is provided in a space surrounded by the two flexible actuating bodies 2A, 2B in plan view (see FIGS. 4 and 6). The shaft 4 is formed in a cylindrical shape. The diameter of the shaft 4 is larger than the thickness of the beams 3A, 3B. The other ends of the first beams 3A, 3B are connected to one axial side of the shaft 4. The other ends of the second beams 3A, 3B are connected to the other axial side of the shaft 4. The shaft 4 may be fixed to a shaft (not shown).

[0028] The configurations (arrangement, shape, size, etc.) of the flexible actuators 2A, 2B (including the curved flexible portions 21A, 21B), beam portions 3A, 3B, and shaft portion 4 that constitute the manipulator 1 are not limited to those described above and can be changed according to design specifications.

[0029] <Example of Manipulator Operation> Referring to Figures 2 and 3 together, the manipulator 1 is configured to be able to apply displacement to the mechanism end portions 5A and 5B in the axial longitudinal direction (the direction of the arrows shown in Figures 2 and 3) by driving an actuator (not shown).

[0030] When the mechanism terminals 5A and 5B are displaced in the longitudinal direction of the shaft, a bending moment is transmitted to the beams 3A and 3B through the curved flexible sections 21A and 21B, causing a bending motion at the tip. For example, displacing the two mechanism terminals 5A and 5B in opposite directions causes the manipulator 1 to bend (see Figure 2). On the other hand, displacing the two mechanism terminals 5A and 5B in the same direction causes the manipulator 1 to open and close (see Figure 3).

[0031] Since the flexible actuating bodies 2A, 2B include curved flexible sections 21A, 21B, linear displacement is converted into rotational motion around the shaft section 4, thereby performing bending or opening / closing motion of the manipulator 1. The manipulator 1 is equipped with a beam pseudo-rotation mechanism (pseudo-rotation joint) consisting of beam sections 3A, 3B connected at one end to the flexible sections 21A, 21B and a shaft section 4 connected at the other end of the beam sections 3A, 3B. This pseudo-rotation joint converts motion by the curved flexible sections 21A, 21B without generating friction. The manipulator 1 constitutes a flexible robotic forceps mechanism using a pseudo-rotation joint.

[0032] <Effects> As described above, the manipulator 1 of the above embodiment includes at least one flexible actuator 2A, 2B including curved flexible portions 21A, 21B, beams 3A, 3B having one end connected to the flexible portions 21A, 21B, and a shaft 4 having the other end connected to the beams 3A, 3B. The flexible actuators 2A, 2B are configured to be movable without sliding relative to the beams 3A, 3B and the shaft 4. With this configuration, the flexible actuators 2A, 2B are configured to be movable without sliding relative to the beams 3A, 3B and the shaft 4, and thus can operate without generating friction. Therefore, wear can be suppressed. For example, in a configuration in which parts rub against each other, wear powder is generated at the sliding portions, causing issues in terms of biocompatibility and durability. In contrast, with this configuration, the non-sliding movement suppresses wear, thereby improving biocompatibility and durability.

[0033] In the above embodiment, the flexible actuating bodies 2A and 2B, the beams 3A and 3B, and the shaft 4 are integrally formed from the same material. This configuration simplifies the structure and reduces the number of parts compared to when the flexible actuating bodies, the beams, and the shaft are integrally formed from different materials.

[0034] In the above embodiment, the same components are made of a polymer material. This configuration reduces material costs and manufacturing costs compared to when the same components are made of a metal material (such as Ni-Ti), thereby contributing to disposability.

[0035] In the above embodiment, at least one flexible actuator 2A, 2B includes two flexible actuators 2A, 2B consisting of a first flexible actuator 2A arranged at an interval on one side in the radial direction of the shaft portion 4 and a second flexible actuator 2B arranged at an interval on the other side in the radial direction of the shaft portion 4. According to this configuration, each of the two flexible actuators 2A, 2B can perform an operation without generating friction.

[0036] In the above embodiment, the two flexible actuating bodies 2A, 2B are arranged such that at least the flexible portions 21A, 21B of each are spaced apart in the axial direction of the shaft portion 4. According to this configuration, operation can be performed without generating friction between the flexible portions 21A, 21B of each of the two flexible actuating bodies 2A, 2B.

[0037] <Modifications> In the above embodiment, the flexible actuating body, the beam portion, and the shaft portion are integrally formed from the same member, but this is not limiting. For example, the flexible actuating body, the beam portion, and the shaft portion may be integrally formed from different members. The configurations of the flexible actuating body, the beam portion, and the shaft portion can be changed according to design specifications.

[0038] In the above embodiment, the same members are formed of a polymer material, but this is not limiting. For example, the same members may be formed of a metal material (such as Ni-Ti). The material of the same members can be changed depending on the design specifications.

[0039] In the above embodiment, an example has been described in which the at least one flexible actuator includes two flexible actuators: a first flexible actuator arranged at an interval on one side of the shaft in the radial direction, and a second flexible actuator arranged at an interval on the other side of the shaft in the radial direction. However, this is not limited to this. For example, the at least one flexible actuator may be composed of only the first flexible actuator arranged at an interval on one side of the shaft in the radial direction. For example, the at least one flexible actuator may be configured to include three or more flexible actuators arranged at intervals on the radial outward side of the shaft. The configuration of the at least one flexible actuator can be changed according to design specifications.

[0040] In the above embodiment, an example has been described in which at least the flexible portions of the two flexible actuators are arranged with a gap in the axial direction of the shaft, but this is not limiting. For example, the flexible portions of the two flexible actuators may be in contact with each other in the axial direction of the shaft. The arrangement of the flexible portions of the two flexible actuators can be changed according to design specifications.

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and additions, omissions, substitutions, and other modifications to the configuration are possible within the scope of the spirit of the present invention, and the above-described embodiments can also be combined as appropriate.

[0042] The manipulator according to the above embodiment of the present invention will be specifically described below by showing an example. Note that the following example is a specific example to which the present invention is applied, and does not limit the present invention.

[0043] <Evaluation by Finite Element Analysis> A manipulator made of polymeric material was evaluated using finite element analysis. Analysis was performed for 60-degree bending and 120-degree opening and closing movements, and von Mises stress was used for evaluation. Both ends of the shaft were fixed, and linear displacement was applied to the end of the mechanism in the longitudinal direction of the shaft. The maximum stress and stress distribution were observed when the tip of the forceps (tip of the working part) reached a predetermined angle. ANSYS MOTION 2021 R1 (ANSYS Inc., US) was used for the analysis, and FEMAP 2020.2 STUDENT (Siemens Inc., Germany) was used to generate the mesh for the model. TPU (Young's modulus 9.4 MPa, tensile strength 29.0 MPa, Poisson's ratio 0.49) was selected as the polymeric material due to its high flexibility and mechanical strength.

[0044] Fig. 10 shows the results of finite element analysis of the example. As shown in Fig. 10, the maximum stress when bent at 60 degrees was 1.83 MPa, and the maximum stress when opened and closed at 120 degrees was 1.34 MPa. These values ​​are sufficiently small compared to the tensile strength of TPU, which is 29.0 MPa.

[0045] <Evaluation Using Prototype> A prototype was implemented and tested to evaluate the difference in forceps tip angle between the finite element analysis and the prototype. Figure 11 shows the external appearance of the experimental device used in this example. Figure 12 shows the results of video analysis of this example. The forceps part of the prototype was created using an FDM 3D printer (AnkerMakeM5, Anker, China) and was made of TPU (PolyFlex TPU95, Polymaker, China). The shaft was made from a processed acrylic pipe with an outer diameter of 10 mm and an inner diameter of 8 mm. Two linear motors (L12-R, Actuonix, Canada) were used to apply linear displacement to the end of the mechanism.

[0046] The experiment was divided into three parts: bending in both directions and opening and closing. The experimental procedure is as follows: (1) A visual marker was attached to the tip of the prototype blade. (2) The linear displacement of the end required to produce a ±60-degree rotational movement, calculated from the results of finite element analysis, was generated by a motor, and bending and opening movements were performed 10 times each. (3) The movements were filmed, and the trajectory of each marker was tracked using video analysis software to determine the tip angle of the forceps. (4) From the angles obtained, the average and standard deviation of the bending and opening angles were calculated.

[0047] The camera used for video recording was an α99II (Sony Inc., Japan), the lens was a SAL100M28 (Sony Inc., Japan), and the video analysis software was VW-H2MA (KEYENCE Inc., Japan).

[0048] The analysis results are shown in Table 1.

[0049]

[0050] In this experiment, an input equivalent to a ±60° rotation was applied, and an opening angle of 120° was expected during the opening and closing motion. However, the actual opening angle was only 101.5°. This is thought to be due to deflection occurring in the input section when the distal end was pushed toward the tip by the motor. In fact, this deflection can be confirmed in the video (see Figure 12 (2)). The bending angle was closer to the expected value of 60° than in the opening and closing motion. The reason why the results were closer to those of the finite element analysis than those of the opening and closing motion is thought to be that while loss due to deflection occurred in the input section on the pushing side, no deflection occurred in the other input section because the input was in the opposite direction from the pushing side.

[0051] REFERENCE SIGNS LIST 1 Manipulator 2A First flexible actuating body (flexible actuating body) 2B Second flexible actuating body (flexible actuating body) 3A, 3B Beam portion 4 Shaft portion 21A, 21B Flexible portion

Claims

1. A manipulator comprising: at least one flexible actuator including a curved flexible portion; a beam portion having one end connected to the flexible portion; and a shaft portion having the other end connected to the beam portion, wherein the flexible actuator is configured to be movable without sliding relative to the beam portion and the shaft portion.

2. The manipulator according to claim 1, wherein said flexible actuator, said beam portion and said shaft portion are integrally formed from the same member.

3. The manipulator according to claim 2, wherein said identical members are formed of a polymeric material.

4. A manipulator as described in claim 1, wherein said at least one flexible actuator includes two flexible actuators consisting of a first flexible actuator arranged at a distance from one another on one radial side of said shaft portion, and a second flexible actuator arranged at a distance from one another on the other radial side of said shaft portion.

5. The manipulator according to claim 4, wherein at least each of said two flexible actuating bodies has a flexible portion spaced apart from each other in the axial direction of said shaft portion.

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