Link Systems and Robot Arms

Abstract

To provide a compact link mechanism with a high degree of freedom. [Solution] The link system 3 includes at least four links and at least two connecting rods connecting every other link, each of which includes a first rotary joint, a second rotary joint, and a third rotary joint. Adjacent links are rotatably connected to each other by the first rotary joint and the second rotary joint. The connecting rods diagonally cross the links between the links they connect and rotatably connect the links by the first rotary joint and the third rotary joint. When the links are linearly extended, the connecting rods are arranged approximately parallel to each other, and each connecting rod is located above the second rotary joint. Rotation of the first rotary joint causes the link system 3 to retract and extend. Rotation of the second rotary joint causes the link system 3 to bend.

Description

[Technical Field]

[0001] The present disclosure relates to a link system and a robotic arm. [Background technology]

[0002] A mechanism (hereinafter referred to as a "winding truss structure") that achieves one degree of freedom of winding and extension by a chain of four-link mechanisms of a closed link system has been disclosed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-35514 Summary of the Invention [Problem to be solved by the invention]

[0004] In the winding truss structure of Patent Document 1, even if an attempt is made to bend each link in a direction different from the winding and extension direction (hereinafter simply referred to as the "extension direction"), it is not possible to bend it because the links and rods interfere with each other (hereinafter in this specification, bending in a direction different from the extension direction will be referred to as "bending"). In other words, because the degree of freedom of movement is limited to one dimension in the extension direction, there are issues such as not being able to use it to reach a target point while avoiding obstacles, or not being able to reach a target point that is in a direction different from the extension direction. [Means for solving the problem]

[0005] To solve the above problems, one embodiment of the present invention provides a link system that can retract, extend, and bend, and includes at least four links and at least two connecting rods connecting every other link. Each link includes a first rotary joint that can rotate about a first rotation axis, a second rotary joint that can rotate about a second rotation axis that faces a direction different from the first rotation axis, and a third rotary joint that can rotate about the first rotation axis and the second rotation axis. Adjacent links are rotatably connected to each other by the first rotary joint and the second rotary joint. The connecting rod diagonally crosses a link between the links to be connected and rotatably connects the links to be connected by the first rotary joint and the third rotary joint. When the links are linearly extended, the connecting rods are arranged approximately parallel to each other. When the links are linearly extended, each connecting rod is located above the second rotary joint. Rotation of the first revolute joint causes the link system to retract and extend, and rotation of the second revolute joint causes the link system to bend.

[0006] In one embodiment of the linkage system, the first axis of rotation and the second axis of rotation may be substantially perpendicular.

[0007] In one embodiment of the link system, the first axis of rotation may be substantially parallel to a horizontal plane.

[0008] In one embodiment of the link system, the second axis of rotation may be substantially parallel to the vertical direction.

[0009] In one embodiment of the link system, the second rotation axis and a line segment connecting the opposing first and third rotation joints are substantially aligned.

[0010] Another aspect of the present disclosure is a robotic arm, the robotic arm including any of the link systems described above.

[0011] Any combination of the above components, and conversion of the present disclosure into a method, device, system, recording medium, computer program, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0012] According to the present disclosure, a rolled-up truss structure can be realized that has the freedom to bend in addition to being rolled up and extended. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a schematic diagram of a link system according to a comparative example. [Figure 2] FIG. 10 is a schematic diagram showing a state in which a link system according to a comparative example is extended. [Figure 3] FIG. 10 is a schematic diagram showing a state in which a link system according to a comparative example is wound up. [Figure 4] FIG. 2 is a schematic diagram illustrating a case where a virtual rotation axis is provided to the link system of FIG. 1. [Figure 5] FIG. 1 is a schematic diagram of a link system according to a first embodiment. [Figure 6] The upper diagram is a diagram extracted from Fig. 5. The lower diagram is a schematic perspective view of the upper diagram. [Figure 7] FIG. 10 is a schematic diagram of a link system 3 according to a second embodiment. [Figure 8] FIG. 10 is a diagram showing a link system in which three bending axes are arranged for four links. [Figure 9] This figure shows the range of motion of the tip of the link system when the magnitude of θi is changed. (a) shows the range of motion when -30°≦θi≦30°, (b) shows the range of motion when -45°≦θi≦45°, and (c) shows the range of motion when -60°≦θi≦60°. [Figure 10] These are side photographs of the prototype link system. (a) shows the link system when fully retracted, (b) shows the link system as it is being extended, and (c) shows the link system when it is fully extended. [Figure 11]These are photographs of the prototype link system taken from the front. (a) shows a state where none of the links are bent, (b) shows a state where all of the links are bent to the right when viewed from the front, (c) shows a state where all of the links are bent to the left when viewed from the front, and (d) shows a state where some links are bent to the right and some are bent to the left when viewed from the front. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described below based on preferred embodiments with reference to the drawings. In the embodiments and modifications, identical or equivalent components and members are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The dimensions of the components in the drawings are enlarged or reduced as appropriate for ease of understanding. Some components that are not important for explaining the embodiments are omitted from the drawings. Terms including ordinal numbers such as "first" and "second" are used to describe various components, but these terms are used only to distinguish one component from another and do not limit the components.

[0015] [Rolling truss structure] Before describing specific embodiments, we will explain the winding truss structure that forms the basic idea of ​​this disclosure. Many conventional linear actuators have a small extension ratio, usually less than twice that of a full-size actuator. Furthermore, these linear actuators require a large installation space compared to their stroke length. Furthermore, as the stroke length increases, the weight of the entire actuator increases exponentially. In addition, many pneumatic and hydraulic linear actuators only have a two-point stop function, and have the problem of being unable to achieve intermediate positions.

[0016] Furthermore, telescopic linear actuators, which have a high extension ratio and a compact installation space, also have limitations. For example, in the case of rigid chain actuators, the articulated chain is stored compactly and can be deployed at high speeds (1000 mm / s). However, a drawback of this mechanism is that it cannot withstand forces acting perpendicular to the extension axis. This is because such forces cause the articulated chain to bend and fold when stored. The Zip Chain Actuator solves this problem by using two articulated chains that work together to form a highly rigid support that constrains all axes and allows for high-speed operation. However, this actuator has the drawback of requiring two articulated chains to constrain all axes, resulting in a large installation space.

[0017] Spiral lift and helical band actuators can be operated in a smaller installation space than existing telescopic linear actuators. However, when extending spiral lift and helical band actuators, despite their high extension ratio, they have the disadvantage of slower operating speeds (maximum of about 10 mm / s) compared to conventional direct drive actuators such as rigid chain actuators. This is due to the speed constraints of the interlocking process, in which the metal band is rotated spirally to form a tube. On the other hand, this mechanism is constrained on all axes, allowing it to resist forces at any extension point.

[0018] In response to this, a link system having a structure called a winding truss structure has been proposed (see, for example, Patent Document 1). FIG. 1 is a schematic diagram of a link system 1 based on a winding truss structure, which serves as a comparative example of the link system of the embodiment of the present disclosure. Link system 1 includes four links, namely, a first link 11, a second link 12, a third link 13, and a fourth link 14. Link system 1 further includes two connecting rods, namely, a first connecting rod 21 and a second connecting rod 22.

[0019] In the example of FIG. 1 , the first link 11 is I-shaped. The second link 12, the third link 13, and the fourth link 14 are T-shaped. The first connecting rod 21 and the second connecting rod 22 are I-shaped. Through holes are provided near both ends and near the center of the first link 11. Through holes are also provided near both ends of the first connecting rod 21 and the second connecting rod 22. Through holes are also provided near both ends of the two rods that make up the T shape of the second link 12, the third link 13, and the fourth link 14, and near where these two rods intersect. By overlapping the links and connecting rods and aligning their through holes, and then passing a connecting pin through the aligned through holes, the links and connecting rods can be pivotally connected to each other so that they can rotate.

[0020] The first link 11 and the second link 12 are pivotally connected at a through hole 45. The second link 12 and the third link 13 are pivotally connected at a through hole 46. The third link 13 and the fourth link 14 are pivotally connected at a through hole 47. The first link 11 and the first connecting rod 21 are pivotally connected at a through hole 41. The third link 13 and the first connecting rod 21 are pivotally connected at a through hole 43. The second link 12 and the second connecting rod 22 are pivotally connected at a through hole 42. The fourth link 14 and the second connecting rod 22 are pivotally connected at a through hole 44. That is, the first link 11 and the third link 13 are connected via the first connecting rod 21. Similarly, the second link 12 and the fourth link 14 are connected via the second connecting rod 22.

[0021] The first connecting rod 21 diagonally crosses the second link 12 located between the first link 11 and the third link 13 to be connected, thereby connecting the first link 11 and the third link 13. The second connecting rod 22 diagonally crosses the third link 13 located between the second link 12 and the fourth link 14 to be connected, thereby connecting the second link 12 and the fourth link 14. In other words, the connecting rod diagonally crosses the links located between the links to be connected, thereby rotatably connecting the links to be connected.

[0022] The first connecting rod 21 and the second connecting rod 22 are disposed substantially parallel to each other. That is, when the link is extended linearly, the connecting rods are disposed substantially parallel to each other.

[0023] In the example of Fig. 1, the first connecting rods 21 are arranged on the back side of each link when viewed from the side of the page, while the second connecting rods 22 are arranged on the front side of each link when viewed from the side of the page.

[0024] Hereinafter, a link system consisting of four links and two connecting rods, as shown in Figure 1, will be referred to as a "unit link mechanism." Longer link systems can be realized by sequentially adding and connecting links and connecting rods to the unit link mechanism.

[0025] 2 and 3 schematically show a link system 2 in which eight links and eight connecting rods are added to the unit link mechanism. That is, the link system 2 includes a first link 11, a second link 12, a third link 13, a fourth link 14, a fifth link 15, a sixth link 16, a seventh link 17, an eighth link 18, a ninth link 19, a tenth link 10a, an eleventh link 11a, a twelfth link 12a, a first connecting rod 21, a second connecting rod 22, a third connecting rod 23, a fourth connecting rod 24, a fifth connecting rod 25, a sixth connecting rod 26, a seventh connecting rod 27, an eighth connecting rod 28, a ninth connecting rod 29, and a tenth connecting rod 20a. FIG. 2 shows the link system 2 extended linearly. Figure 3 shows the link system 2 wound in a curved shape. In both Figures 2 and 3, the parts surrounded by dotted lines are unit link mechanisms.

[0026] The link system 2 that is linearly extended as shown in Figure 2 can be wound up as follows. First, while fixing the first link 11 at the left end so that it does not move, a clockwise force is applied to the second link 12. In this case, the clockwise force is a force in the direction that increases the angle between the extension direction of the link system 2 and the longitudinal direction of the connecting rod.

[0027] As a result, the second link 12 attempts to rotate clockwise around the through hole 45. However, because the link 12 is connected to the connecting rod 22, the link 12 cannot rotate unless the link 14 rotates clockwise. However, the link 12a at the right end of the 12th link can rotate clockwise because it is not connected to a link that corresponds to the connecting rod 22 when viewed from the link 12. This causes the 12th link 12a to bend downward relative to the extension direction of the link system 2. When the 12th link 12a begins to rotate, the link 11a also rotates clockwise little by little, with a delay, via the connecting rod 20a that is directly connected to the 12th link. This rotation delay occurs because the rotation angle of the link 12a is always larger than the rotation angle of the link 11a. When the area around the through hole 45 of the first link 11 is considered the "root," the above movement can be said to be such that the 12th link 12a, the 11th link 11a, and the 10th link 10a rotate clockwise in sequence from the tip.

[0028] When the twelfth link 12a reaches the joint angle limit, it can no longer rotate (bend). For example, the joint angle is reached when the connecting shaft between the connecting rod 28 and the link 10a in FIG. 3 comes into contact with the connecting rod 20a.

[0029] In this way, starting from the tip link, each link rotates one after the other until it reaches its joint angle limit. This allows the link system 2 to be wound in a curved shape (a clockwise spiral in Figure 2) while sequentially shifting the bending location toward the base. A link that has reached its rotation limit can be considered rigid in the bending direction.

[0030] Here, it is important to note that When starting to wind, always secure the base link and apply force to the tip link. The direction of the applied force is the direction that increases the angle between the extension direction of the link system and the longitudinal direction of the connecting rod (clockwise in Figure 2). Since the tip bent to the joint angle limit can be regarded as a rigid body, the above force can also be achieved by applying torque in the winding direction to the tip of link system 2. Even if a force is applied in the opposite direction to the above (counterclockwise in Figure 2), link system 2 will not move.

[0031] In Figure 3, the twelfth link 12a to the sixth link 16 are fully wound up to the joint angle limit (i.e., rigid), the fifth link 15 to the third link 13 are in the winding process, and the second link 12 is extended (i.e., has no bending).

[0032] The link system 2 wound up in a curved shape as shown in Figure 3 can be stretched as follows: First, while fixing the stretched links (tenth link 10a to twelfth link 12a in Figure 3) so that they do not move, a force is applied in the stretching direction (counterclockwise in Figure 3) to the links in the winding process.

[0033] As a result, the third link 13 starts to rotate counterclockwise. When the third link 13 starts to rotate, the fourth link 14, which is directly connected to the third link, and the fifth link 15, via the connecting rod 23, also rotate counterclockwise at an accelerated rate.

[0034] In this way, starting from the root link, each link rotates counterclockwise until it becomes straight.

[0035] Here, it is important to note that When starting to stretch, always fix the already stretched link and apply force in the stretching direction to the next link. When the link to which force is applied becomes straight, apply force to the next link. To sequentially apply force to the next link, torque can be applied to the link that has reached its joint angle limit in the direction of extension (counterclockwise) at the tip of the link system 2. These are the three points:

[0036] If the members constituting each link and each connecting rod have sufficient rigidity and there is no substantial slack in the connections between each link and between each link and each connecting rod, the extended portion of the above link system can be considered a rigid body. Therefore, this link system can be used in structures such as linear actuators and flexible trusses. Furthermore, since the wound portion of the above link system is spiral-shaped, a large extension ratio can be obtained. In addition, the above link system can be stopped and started at any desired position.

[0037] In this way, the winding truss structure has the advantages of a high extension ratio, the ability to stop at multiple points, and a small, compact installation space.

[0038] As explained above, the link system shown in Figures 1 to 3 has a degree of freedom of movement in one dimension in the winding and extending directions. However, in practice, in addition to this degree of freedom, it is desirable for the link system to have a degree of freedom of movement, for example, bending in a direction perpendicular to the extension direction when the link system is extended. For example, if the winding and extending movement of the link system is likened to the winding and extending of an elephant's nose, it is desirable for the nose to be able to bend and swing left and right.

[0039] For this purpose, for example, consider providing an imaginary rotation axis z to the fourth link 14 of the link system 1 in Figure 1 and rotating the fourth link 14 around the rotation axis z (see Figure 4). However, as can be seen from Figure 4, in this case, even if an attempt is made to rotate the portion of the fourth link 14 to the right of the rotation axis z around the rotation axis z, the rotation is impossible because the fourth link 14 interferes with the second connecting rod 22. The following embodiment solves this problem.

[0040] [First embodiment] Figure 5 schematically shows the link system 3 according to the first embodiment. Figure 5 shows the link system 3 in an extended state. The link system 3 includes four links, namely, a first link 101, a second link 102, a third link 103, and a fourth link 104. The link system 3 further includes two connecting rods, namely, a first connecting rod 201 and a second connecting rod 202.

[0041] The link system 3 further includes six first rotary joints rotatable around first rotation axes, namely, first rotary joint 301, first rotary joint 302, first rotary joint 303, first rotary joint 304, first rotary joint 305, and first rotary joint 306.

[0042] The link system 3 further includes three second rotary joints, namely, second rotary joint 401, second rotary joint 402, and second rotary joint 403, which are rotatable around second rotary axes facing in a direction different from the first rotary axis.

[0043] The link system 3 further includes three third rotary joints, namely, third rotary joint 501, third rotary joint 502, and third rotary joint 503, which are rotatable around the first and second rotation axes.

[0044] The link system 3 further includes a fourth rotary joint 601 rotatable about the first connecting rod 201 and a fourth rotary joint 602 rotatable about the second connecting rod 202 .

[0045] In this example, the first rotation axis is oriented in a direction perpendicular to the paper surface, and the second rotation axis is oriented in a vertical direction parallel to the paper surface. That is, in this example, the orientation of the first rotation axis and the orientation of the second rotation axis are perpendicular to each other. The first rotation joint and the second rotation joint may be configured using, for example, a shaft and a bearing, but are not limited to this.

[0046] The third rotary joint is rotatable around the first rotation axis and the second rotation axis. That is, the third rotary joint has two degrees of freedom in rotational directions, one in the direction of the first rotation axis and the other in the direction of the second rotation axis. The third rotary joint may be configured using, for example, a universal joint or a ball joint, but is not limited to these.

[0047] Link 101 and link 102 are adjacent to each other. These links are rotatably connected to each other by a first rotary joint 304 and a second rotary joint 401. Link 102 and link 103 are adjacent to each other. These links are rotatably connected to each other by a first rotary joint 305 and a second rotary joint 402. Link 103 and link 104 are adjacent to each other. These links are rotatably connected to each other by a first rotary joint 306 and a second rotary joint 403.

[0048] The connecting rod 201 connects the link 101 and the link 103. Specifically, the connecting rod 201 diagonally crosses the link 102 located between the link 101 and the link 103 to be connected, and rotatably connects the link 101 and the link 103 to be connected by the first rotary joint 302 and the third rotary joint 501. The connecting rod 202 connects the link 102 and the link 104. Specifically, the connecting rod 202 diagonally crosses the link 103 located between the link 102 and the link 104 to be connected, and rotatably connects the link 102 and the link 104 to be connected by the first rotary joint 303 and the third rotary joint 502.

[0049] In the state shown in FIG. 5, that is, in the state in which the link 101, the link 102, the link 103, and the link 104 are extended linearly, the connecting rod 201 and the connecting rod 202 are disposed substantially parallel to each other.

[0050] In the state shown in FIG. 5, i.e., when link 101, link 102, link 103, and link 104 are linearly extended, connecting rod 201 is above second rotary joint 402, and connecting rod 202 is above second rotary joint 403.

[0051] Rotation of the first revolute joints 301 , 302 , 303 , 304 , 305 and 306 about the first axis of rotation causes the link system 3 to wind and unwind.

[0052] Rotation of the second rotary joints 401, 402, and 403 about the second rotation axis causes bending of the link system 3. In this sense, the second rotation axis may hereinafter be referred to as the "bending axis." Because the connecting rod 201 is located above the second rotary joint 402, even if the second rotary joint 402 rotates about the second rotation axis (in other words, even if the link 103 rotates about the second rotation axis), the link 102 and the connecting rod 201 do not interfere with each other, and bending movement of the link system 3 is not hindered. Similarly, because the connecting rod 202 is located above the second rotary joint 403, even if the second rotary joint 403 rotates about the second rotation axis (in other words, even if the link 104 rotates about the second rotation axis), the link 103 and the connecting rod 202 do not interfere with each other. Therefore, bending movement of the link system 3 is not hindered.

[0053] The third rotary joints 501, 502, and 503 have two degrees of freedom in rotational directions, that is, in the direction of the first rotation axis and in the direction of the second rotation axis. Therefore, the connecting rods 201 and 202 can move in accordance with the winding, extension, and bending movements of the link system 3.

[0054] The fourth rotary joint 601 and the fourth rotary joint 602 have degrees of freedom in the rotational direction around the first connecting rod 201 and the second connecting rod 202, respectively. Therefore, the following expression is obtained. The connecting rods 201 and 202 can move in accordance with the winding, extension, and bending movements of the link system 3.

[0055] The mechanism for winding, extending and bending of link system 3 is common to link systems 1 and 2, and therefore a detailed description thereof will be omitted.

[0056] 6 is a schematic diagram of link system 3. The upper diagram is a diagram extracting the portion relating to link 102 and link 103 in FIG. 5. The lower diagram is a schematic perspective view of the upper diagram. In the lower diagram, the first rotation axis faces the x-axis direction, and the second rotation axis faces the y-axis direction.

[0057] As described above, according to this embodiment, a winding truss structure can be realized that has the freedom to bend in addition to winding and extending.

[0058] 5, the first rotation axis is substantially parallel to the horizontal plane, but is not limited to this, and the first rotation axis may be tilted from the horizontal plane.

[0059] Similarly, in the example shown in Fig. 5, the second rotation axis is substantially parallel to the vertical direction, but is not limited to this, and the second rotation axis may be oriented in a direction different from the vertical direction.

[0060] [Second embodiment] Fig. 7 schematically shows a link system 4 according to a second embodiment. Fig. 7 shows the link system 4 in an extended state. Similar to the link system 3 of Fig. 5, the link system 4 includes four links, namely, a first link 101, a second link 102, a third link 103, and a fourth link 104. The link system 3 further includes two connecting rods, namely, a first connecting rod 201 and a second connecting rod 202.

[0061] Similar to link system 3, link system 4 further includes six first rotary joints rotatable around first rotation axes, namely, first rotary joint 301, first rotary joint 302, first rotary joint 303, first rotary joint 304, first rotary joint 305, and first rotary joint 306.

[0062] Similar to link system 3, link system 4 further includes three second rotary joints, namely, second rotary joint 401, second rotary joint 402, and second rotary joint 403, that are rotatable around second rotary axes that face in a direction different from the first rotary axes.

[0063] Similar to link system 3, link system 4 further includes three third rotary joints rotatable around the first and second rotation axes, namely, third rotary joint 501, third rotary joint 502, and third rotary joint 503.

[0064] In link system 3, the second rotation axis (i.e., the rotation axis of second rotation joints 401, 402) and the line segments connecting the opposing first and third rotation joints (i.e., the line segment connecting first rotation joint 304 and third rotation joint 501, the line segment connecting first rotation joint 305 and third rotation joint 502, and the line segment connecting first rotation joint 306 and third rotation joint 503) are approximately on a straight line. In contrast, in link system 4, the second rotation axis (i.e., the rotation axis of second rotation joints 401, 402) and the line segments connecting the opposing first and third rotation joints (i.e., the line segment connecting first rotation joint 304 and third rotation joint 501, the line segment connecting first rotation joint 305 and third rotation joint 502, and the line segment connecting first rotation joint 306 and third rotation joint 503) are not on a straight line.

[0065] Similar to the link system 3, the third rotary joint is rotatable around the first and second rotation axes. That is, the third rotary joint has two degrees of freedom in rotational directions, one in the direction of the first rotation axis and the other in the direction of the second rotation axis. The third rotary joint may be configured using, for example, a universal joint or a ball joint, but is not limited to these.

[0066] Similar to link system 3, link 101 and link 102 are adjacent to each other. These links are rotatably coupled to each other by a first rotary joint 304 and a second rotary joint 401. Link 102 and link 103 are adjacent to each other. These links are rotatably coupled to each other by a first rotary joint 305 and a second rotary joint 402. Link 103 and link 104 are adjacent to each other. These links are rotatably coupled to each other by a first rotary joint 306 and a second rotary joint 403.

[0067] Similar to link system 3, connecting rod 201 connects link 101 and link 103. Specifically, connecting rod 201 diagonally crosses link 102 located between link 101 and link 103 to be connected, and rotatably connects link 101 and link 103 to be connected by first rotary joint 302 and third rotary joint 501. Connecting rod 202 connects link 102 and link 104. Specifically, connecting rod 202 diagonally crosses link 103 located between link 102 and link 104 to be connected, and rotatably connects link 102 and link 104 to be connected by first rotary joint 303 and third rotary joint 502.

[0068] As with link system 3, in the state shown in FIG. 7, that is, with link 101, link 102, link 103, and link 104 extended linearly, connecting rod 201 and connecting rod 202 are arranged substantially parallel to each other.

[0069] As with link system 3, in the state shown in FIG. 7, i.e., with link 101, link 102, link 103, and link 104 extended linearly, connecting rod 201 is above second rotary joint 402, and connecting rod 202 is above second rotary joint 403.

[0070] Similar to link system 3, rotation of first revolute joints 301, 302, 303, 304, 305 and 306 about a first axis of rotation causes link system 3 to wind and unwind.

[0071] As with link system 3, rotation of second rotary joints 401, 402, 403 about the second rotation axis causes bending of link system 3. Because connecting rod 201 is located above second rotary joint 402, even if second rotary joint 402 rotates about the second rotation axis (in other words, even if link 103 rotates about the second rotation axis), link 102 and connecting rod 201 do not interfere with each other, and bending movement of system 3 is not hindered. Similarly, because connecting rod 202 is located above second rotary joint 403, even if second rotary joint 403 rotates about the second rotation axis (in other words, even if link 104 rotates about the second rotation axis), link 103 and connecting rod 202 do not interfere with each other. Therefore, bending movement of system 3 is not hindered.

[0072] Similar to link system 3, third rotational joints 501, 502, 503 have two degrees of freedom in rotational directions, that is, in the direction of the first rotation axis and in the direction of the second rotation axis. Therefore, connecting rod 201 and connecting rod 202 can move in accordance with the winding, extension, and bending movements of link system 3.

[0073] According to this embodiment, similar to the first embodiment, it is possible to realize a winding truss structure that has the freedom of bending in addition to winding and extension, while improving the freedom of configuration.

[0074] [Third embodiment] The third embodiment is a robot arm. The above-described link system can be applied to a robot arm. That is, the robot arm of this embodiment includes any of the above-described link systems. In addition to the above-described link system, the robot arm of this embodiment may include any suitable configuration, such as a control device based on software or the like, a user interface for operating the robot arm, a communication device for communicating with an external system, and an end effector attached to the tip of the robot arm.

[0075] According to this embodiment, it is possible to realize a robot arm that has the freedom to bend in addition to winding and extending.

[0076] (Evaluation of range of motion based on changes in rotation around the flexion axis) Below, we will evaluate the range of motion according to the change in the amount of rotation around the bending axis for the link system of the present disclosure. Figure 8 shows a link system in which three bending axes are arranged for four links. The bending axes are assumed to be parallel to the vertical direction. The distance between adjacent bending axes is assumed to be l = 10. Around each bending time, θ i (i=1, 2, 3) rotation is given, and θ i The range of motion of the link system was calculated when the size of

[0077] In Figure 9, θ i The figure shows the range of motion of the tip of the link system when the magnitude of is changed. (a) is -30°≦θ i ≦30°, (b) is -45°≦θ i ≦45°, (c) is -60°≦θ i 9 shows the range of motion when the rotation angle around the bending axis is ≦60°. As shown in Figure 9, it can be seen that the range of motion of the tip changes significantly depending on the rotation angle around the bending axis.

[0078] (Example of implementation) The inventors have prototyped a link system according to an embodiment of the present disclosure and confirmed its operation. In this prototype, winding and extension operations are achieved by wire drive, and bending operations are achieved by individual motors provided near each bending axis.

[0079] Figure 10 shows side photographs of the prototype link system. (a) shows the link system when it is fully retracted, (b) shows the link system when it is being extended, and (c) shows the link system when it is fully extended.

[0080] Figure 11 shows photographs of the prototype link system taken from the front. (a) shows a state where none of the links are bent, (b) shows a state where all of the links are bent to the right when viewed from the front, (c) shows a state where all of the links are bent to the left when viewed from the front, and (d) shows a state where some links are bent to the right and some are bent to the left when viewed from the front.

[0081] [Each aspect of the present disclosure] A link system according to one embodiment of the present disclosure is capable of retracting, extending, and bending, and includes at least four links and at least two connecting rods connecting every other link. Each link includes a first rotary joint rotatable around a first rotation axis, a second rotary joint rotatable around a second rotation axis facing a direction different from the first rotation axis, and a third rotary joint rotatable around the first and second rotation axes. Adjacent links are rotatably connected to each other by the first and second rotary joints. The connecting rods diagonally cross links between the adjacent links and rotatably connect the adjacent links by the first and third rotary joints. When the links are linearly extended, the connecting rods are positioned approximately parallel to each other. When the links are linearly extended, each connecting rod is located above the second rotary joint. Rotation of the first rotary joint causes the link system to retract and extend. Rotation of the second revolute joint causes bending of the link system.

[0082] According to this aspect, it is possible to realize a winding truss structure that has the freedom to bend in addition to winding and extending.

[0083] In one embodiment, the first and second rotation axes of the link system are substantially perpendicular to each other. "Substantially perpendicular" means that the angle between the first and second rotation axes is between 70° and 110°.

[0084] In this embodiment, the two rotation axes are substantially perpendicular to each other, so that the movement is well balanced and stable movement can be achieved.

[0085] In one embodiment, the first rotation axis of the link system is substantially parallel to the horizontal plane. "Substantially parallel" means that the angle between the first rotation axis and the horizontal plane is within 10 degrees.

[0086] In this embodiment, the first rotation axis is hardly tilted relative to the horizontal plane, so stable winding and extension can be achieved.

[0087] In one embodiment, the second rotation axis of the link system is substantially parallel to the vertical direction. "Substantially parallel" means that the angle between the second rotation axis and a vertical line is within 10 degrees.

[0088] In one embodiment, the second rotation axis of the link system and the line segment connecting the opposing first and third rotation joints of the link system are substantially aligned. "Substantially aligned" means that the deviation of the two from the alignment is within 5%.

[0089] In this embodiment, there is almost no misalignment between the second rotation axis and the line segment connecting the opposing first and third rotation joints, so a stable bending movement can be achieved.

[0090] A robot arm according to one aspect of the present disclosure includes any of the link systems described above.

[0091] According to this aspect, it is possible to realize a robot arm that has the freedom to bend in addition to winding and extending.

[0092] The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and treatment processes, and that such modifications are also within the scope of the present disclosure.

[0093] For example, the link shapes in link system 3 in Fig. 5 and link system 4 in Fig. 7 are rectangular. However, the shape of the link is not limited to this, and the link shape may be triangular, or may be a rectangle or triangle with curved sides.

[0094] According to this modification, the shape of the link can be freely designed depending on the purpose and application.

[0095] When understanding the abstract technical ideas of the embodiments and modifications, the technical ideas should not be interpreted as being limited to the contents of the embodiments and modifications. The above-described embodiments and modifications are merely illustrative examples, and many design modifications, such as changes, additions, and deletions of components, are possible. In the embodiments, the contents in which such design modifications are possible are emphasized by adding the notation "embodiment." However, design modifications are also permitted even in contents without such notation. [Industrial Applicability]

[0096] The link system disclosed herein can be applied to various industrial robot arms such as those used in nursing care, medical care, endoscopic surgery, machining, metal processing, and automobile assembly, as well as in a wide range of other fields, such as assisting users in small spaces such as toilets, retrieving space debris, and removing contents from refrigerators. [Explanation of symbols]

[0097] 1. Link system, 2··Link system, 3·· link system, 4-link system, 11··First link, 12··Second link, 13··Third link, 14··Fourth link, 15··5th link, 16··6th link, 17··7th link, 18··8th link, 19··Ninth link, 10a··10th link, 11a··11th link, 12a··12th link, 21... First connecting rod, 22... second connecting rod, 23... third connecting rod, 24··Fourth connecting rod, 25··fifth connecting rod, 26··6th connecting rod, 27··7th connecting rod, 28··Eighth connecting rod, 29. Ninth connecting rod, 20a··10th connecting rod, 41··Through hole, 42··Through hole, 43··Through hole, 44··Through hole, 45··Through hole, 46··Through hole, 47··Through hole, 101··First link, 102··Second link, 103··Third link, 104··Fourth link, 201 First connecting rod 202... second connecting rod, 301... First rotary joint; 302... First rotary joint; 303... First rotary joint; 304... First rotary joint; 305... First rotary joint; 306··First rotary joint; 401... second rotary joint; 402... second revolute joint; 403... Second revolute joint; 501... third revolute joint, 502... A third revolute joint; 503...Third revolute joint, 601··Fourth revolute joint, 602··Fourth rotating joint.

Claims

1. A link system that can reel in and extend and bend, At least four links; At least two connecting rods connecting every other link to each other, each of the links includes a first rotary joint rotatable around a first rotation axis, a second rotary joint rotatable around a second rotation axis facing in a direction different from the first rotation axis, and a third rotary joint rotatable around the first rotation axis and the second rotation axis; Adjacent ones of the links are rotatably connected to each other by the first rotary joint and the second rotary joint, the connecting rod diagonally crosses a link between links to be connected, and rotatably connects the links to be connected by the first rotary joint and the third rotary joint; When the link is linearly extended, the connecting rods are disposed substantially parallel to each other, When the link is linearly extended, each of the connecting rods is located above the second rotary joint; rotation of the first revolute joint causes retraction and extension of the link system; A link system, wherein rotation of the second rotary joint causes bending of the link system.

2. 2. The link system according to claim 1, wherein the first rotation axis and the second rotation axis are substantially perpendicular to each other.

3. 2. The link system of claim 1, wherein the first axis of rotation is generally parallel to a horizontal plane.

4. 2. The link system according to claim 1, wherein the second rotation axis is substantially parallel to the vertical direction.

5. 2. The link system according to claim 1, wherein the second rotation axis and a line segment connecting the opposing first and third rotation joints are substantially on the same straight line.

6. A robot arm comprising a link system according to any one of claims 1 to 5.

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