Joint mechanism

Abstract

The purpose of the present invention is to provide a joint mechanism that is provided with novel functions, such as the function of transmitting driving force and the function of guiding a linear member, by ensuring a prescribed path length for a movement path of a linear member supported by a joint portion having high versatility for performing operations such as rotary motion or linear motion. A joint mechanism 1 according to the present invention is provided with: a joint portion J that connects a first arm member M1 and a second arm member M2; and a passive joint portion PJ which is connected between the arm members and which operates in conjunction with the operation of the arm members. The passive joint portion PJ is provided with a path changing means for changing the movement path of the linear member so as to ensure a prescribed path length, by extending the linear member across all rotating members P pivotally supported at each connection point of a link part PL comprising a plurality of link members L.

Description

Joint mechanism

[0001] This invention relates to a joint mechanism used in devices such as robotic manipulators.

[0002] In devices such as robotic manipulators, the end effector at the tip is attached to the base via multiple links, and these links are connected at the joints, allowing the end effector to operate on multiple axes.

[0003] The motors and other drive sources for operating the end effectors and joints are either built into the respective parts and driven directly, or the drive is transmitted from the drive source via linear components such as drive wires and drive belts.

[0004] For example, Patent Document 1 describes a joint that rotates a gripping part attached to the tip of a manipulator, and a drive wire is crossed over adjacent pulleys forming the joint, so that the path length and phase of the drive wire can be kept constant regardless of the angle change of the joint. Patent Document 2 describes a link unit that is provided with a member that forms the path of the drive wire and a member that maintains the length of the drive wire constant when power is transmitted from the drive unit via the drive wire. Patent Document 3 describes a joint that rotatably connects a first link and a second link, with a pulley provided, and a linear member extending from one end of the first link to the other end of the second link wrapped around the pulley, so that the rotation center of the joint is offset from the center of the pulley so that the change in the path length of the linear member is small when the joint is extended and when it is bent.

[0005] Japanese Patent Publication No. 3912251, Japanese Patent Publication No. 6408767, Japanese Unexamined Patent Publication No. 2023-170617

[0006] The aforementioned patent document describes a method for transmitting power to a robot manipulator using a linear member such as a wire, which accommodates changes in the path length of the linear member in response to extension and flexion movements of the joints. However, it is insufficient to maintain a constant path length.

[0007] For example, Patent Document 1 deals with a special joint structure formed by adjacent pulleys, which presents challenges in terms of versatility. Similarly, Patent Document 2 has a special configuration in which the drive wire is double-wound around the pulley, which may hinder the movement of the drive wire. Furthermore, while Patent Document 3 minimizes changes in the path length of the linear member, it presents challenges in maintaining a constant path length.

[0008] Therefore, the present invention aims to provide a joint mechanism equipped with new functions such as a driving force transmission function and a linear member guiding function by maintaining the movement path of a linear member supported by a highly versatile joint that performs actions such as rotational motion or linear motion at a predetermined path length.

[0009] The joint mechanism according to the present invention comprises a first arm member, a second arm member, a joint portion connecting adjacent ends of the first arm member and the second arm member, and a passive joint portion connected between the first arm member and the second arm member and operating in conjunction with the movement of the first arm member and the second arm member, wherein the passive joint portion is supported so as to be movable in the longitudinal direction of at least a linear member stretched between the first arm member and the second arm member, and is provided with a path changing means for changing the movement path of the linear member to maintain a predetermined path length.

[0010] The present invention, having the above-described configuration, has a passive joint connected between a first arm member and a second arm member, which operates in conjunction with the movements of the first and second arm members. This passive joint supports a linear member stretched between at least the first and second arm members so as to be movable in the longitudinal direction, and includes a path changing means for changing the movement path of the linear member to maintain a predetermined path length. Therefore, when the first and second arm members rotate or move linearly via the joint, the movement path of the linear member supported by the passive joint can be maintained at a predetermined path length. By attaching the passive joint to a joint mechanism that connects the first and second arm members via the joint, it becomes possible to obtain a joint mechanism with new functions such as a driving force transmission function and a linear member guiding function.

[0011] This is a schematic diagram of the first embodiment of the joint mechanism according to the present invention. This is a schematic diagram showing a linear member stretched across the joint mechanism shown in Figure 1. This is an explanatory diagram regarding the path length of the movement path of the linear member. This is an explanatory diagram showing that the movement path of the linear member is maintained at a predetermined path length. This is a schematic diagram of a specific example of a rotating joint mechanism. This is a schematic diagram showing a linear member stretched across the joint mechanism shown in Figure 5. This is a schematic diagram of another specific example of a rotating joint mechanism. This is a schematic diagram showing a linear member stretched across the joint mechanism shown in Figure 7. This is a schematic diagram of the second embodiment of the joint mechanism according to the present invention. This is a schematic diagram showing a linear member W stretched across the joint mechanism shown in Figure 9. This is an explanatory diagram showing that the movement path of the linear member is maintained at a predetermined path length. This is a schematic diagram of the third embodiment of the joint mechanism according to the present invention. This is a schematic diagram and operation explanatory diagram showing a linear member stretched across the joint mechanism shown in Figure 12. This is an explanatory diagram showing that the movement path of the linear member of the joint mechanism shown in Figure 12 is maintained at a predetermined path length.

[0012] Embodiments of the present invention will be described below with reference to the drawings. While the embodiments described below are preferred examples for carrying out the present invention and therefore have various technical limitations, the present invention is not limited to these forms unless specifically stated in the following description to limit the present invention.

[0013] Fig. 1 is a schematic configuration diagram of a first embodiment of a joint mechanism according to the present invention. In this example, the joint mechanism 1 rotatably connects a first arm member M1 and a second arm member M2 via a joint J, and a passive joint PJ formed by connecting a plurality of link members is connected between the first arm member M1 and the second arm member M2.

[0014] Adjacent ends of the first arm member M1 and the second arm member M2 are connected by the joint J, so that the first arm member M1 and the second arm member M2 rotate mutually around a rotation center O. The passive joint PJ operates in conjunction with the operations of the first arm member M1 and the second arm member M2.

[0015] The passive joint PJ includes a plurality of link members L1 to L 2n-1 , which are rotatably connected to each other to form a link part PL; a support link member LS1 serving as a first support part, one end of which is fixed to the first arm member M1 and the other end of which is rotatably connected to an end of the link member L1 that is the starting point of the link part PL; and a support link member LS2 serving as a second support part, the other end of which is fixed to the second arm member M2 and one end of which is rotatably connected to an end of the link member L that is the end point of the link part PL 2n-1 .

[0016] The link part PL includes a first link part PL1 formed by rotatably connecting link members L1 to L n-1 and a second link part PL2 formed by rotatably connecting link members L n+1 to L 2n-1 , wherein the first link part PL1 and the second link part PL2 are each configured by connecting (n-1) link members, and between the end of the link member L n-1 that is the end point of the first link part PL1 and the end of L n+1 that is the starting point of the second link part PL2, the two ends are rotatably connected to each other via a link member L n provided with a link connecting part LJ.

[0017] And, a connection point o1 of the link member L1 that is the starting point of the first link part PL1 and the connection point o of the link member L that is the end point of the second link part PL2 2n-1 ​2n The angle bisector T between a pair of straight lines T1 and T2 that connect the rotation center O of the joint J to each other. w When setting the link connection LJ, the bisector T w It is set to be movable along the line.

[0018] Furthermore, the first link section PL1 and the second link section PL2 are bisectors T w Each link member is connected in a manner that is symmetrical with respect to the first link member M1 and the second arm member M2, when they rotate relative to each other around the joint J, the passive joint PJ moves each link member in conjunction with the rotational movement while maintaining the symmetrical relationship between the first link member PL1 and the second link member PL2.

[0019] Furthermore, the passive joint PJ has connecting points o1 to o from the starting point to the ending point of the link PL, which are used as means for changing the movement path of the linear member W, as described later. 2n Multiple rotating members P1 to P are each pivotally supported on the same axis. 2n The linear member W is stretched and suspended across all of the rotating members. In this example, the linear member W is stretched between adjacent rotating members so as to intersect with the link members and is set to move in a zigzag pattern between the rotating members.

[0020] Figure 2 is a schematic diagram showing a linear member W spanning the joint mechanism shown in Figure 1. In this example, the linear member W is transported along the length of the line from the first arm member M1 side, wrapped around a rotating member P1 attached to the passive joint PJ, spanned across a link member, and wrapped around a rotating member P2. Thereafter, it is sequentially spanned between adjacent rotating members, spanning across link members, and then around the rotating member P2. 2n After being wrapped around, the rotating member P is supported by the second arm member M2. m It is wrapped around the second arm member M2 and transported to the outside along the longitudinal direction of the second arm member M2. In this way, a movement path is established between the first arm member M1 and the second arm member M2, with the rotating member traversing in a zigzag pattern.

[0021] When the joint mechanism 1 performs a rotational operation, the movement path of the linear member W up to the rotating member P1 supported and fixed to the first arm member M1 is constant, and the rotating member P supported and fixed to the second arm member M2 2n Since the movement path of the linear member W from along the second arm member M2 is constant, it is only necessary to study the change in path length by focusing on the change in the movement path from the rotating member P1 to the rotating member P 2n up to said position.

[0022] Specifically, the change in the path length of the movement path between the intersection point A with the straight line T1, which is the starting point at which the linear member W winds around the rotating member P1, and the intersection point D with the straight line T2, which is the point at which the linear member W winds around and separates from the rotating member P 2n will be studied.

[0023] FIG. 3 is an explanatory diagram relating to the path length of the movement path of the linear member W. In FIG. 3, when the movement path of the linear member W from the intersection point A to the intersection point D is divided into two by a bisector T w , the first link portion PL1 and the second link portion PL2 are axisymmetric. Therefore, when the rotating members P n+1 to P 2n are folded back along the bisector T w , they overlap with the rotating members P1 to P n .

[0024] Then, the path obtained by folding back the movement path of the rotating members P n+1 to P 2n is set to intersect the movement path of the rotating members P1 to P n at each link member, and the folding point D' of the intersection point D is set on the diagonal line connecting the intersection point A and the connection point o1. Therefore, the movement path from the intersection point A, folded back at the bisector T w to the folding point D' is constituted by the length of the arcs wound around each rotating member and the tangent lines spanned between the rotating members.

[0025] FIG. 4 is an explanatory diagram showing that the movement path of the linear member W is maintained at a predetermined path length. In FIG. 4, the outer peripheries of three adjacent rotating members are indicated by circles, and the connection points o, which are the center points of the outer circumferential circles of the respective rotating members, k-1 , o k and o k+1 are connected to the link member Lk-1 and L k Because they are connected by dotted lines (illustrated), the distance between each connection point remains constant even when they move relative to each other. Therefore, the tangent lines (illustrated by dotted lines) connecting the outer circles corresponding to the movement paths of the linear members spanning each rotating member also remain constant.

[0026] Also, the connecting point o k If we denote the points of tangency of the tangents on the outer circle of the rotating member as X, X', Y, and Y', then the lengths of arcs XY' and YX' are constant, so the connection point o k The sum of the lengths of arcs XY and X'Y', which form the movement path of the rotating member on its outer circumference, is constant.

[0027] Therefore, the rotating members P1 to P that constitute the folded path shown in Figure 3 n A pair of tangents and rotating members P2 to P that intersect and connect each of them n-1 The sum of the arc lengths on the outer circle in this case will all be kept constant.

[0028] Furthermore, with respect to the arc-shaped path on the outer circumference of the rotating member P1, the length of the arc between the point of contact X and Y' of the pair of intersecting tangents with the rotating member P2 is constant, and since the intersection point A and the turning point D' are located diagonally with respect to the connection point o1, the length of the arc AD' is constant. Therefore, the sum of the lengths of the arcs AX and Y'D' is constant.

[0029] From the above, the turning path from intersection A to turning point D' changes as the movement path of the linear member W changes with the movement of the passive joint PJ, but the length of the turning path is maintained.

[0030] In the examples described above, a basic configuration for maintaining a predetermined path length when the linear member W moves in the passive joint PJ has been explained. However, any configuration that allows the passive joint PJ to deform while maintaining the symmetry described above is acceptable, and is not particularly limited.

[0031] Figure 5 shows a schematic configuration diagram (Figure 5(a)) and an operation diagram (Figure 5(b)) relating to a specific example of a rotating joint mechanism. In this example, the passive joint PJ comprises a link section PL in which link members L1 to L3 are rotatably connected to each other, a support link member LS1 which is a first support section with one end fixed to a first arm member M1 and the other end rotatably connected to the end of link member L1, which is the starting point of the link section PL, and a support link member LS2 which is a second support section with the other end fixed to a second arm member M2 and the other end rotatably connected to the end of link member L3, which is the endpoint of the link section PL.

[0032] The link section PL comprises a first link section PL1 consisting of a link member L1 and a second link section PL2 consisting of a link member L3. Link members L1 and L3 are rotatably connected to each other by a link member L2 to which a linear link member LL, which is a link connecting section, is attached. The linear link member LL has a sliding part S that is movably mounted along a linear shaft member whose end is rotatably connected to the joint section J, and the sliding part S is supported and fixed to the link member L2.

[0033] Furthermore, link members L1 and L3, as well as support link members LS1 and LS2, are all set to be the same length, and link member L2 is set so that the lengths between the sliding part S and the connection points o2 and o3 are equal, so that the first link part PL1 and the second link part PL2 are set to be symmetrical with respect to the axis of movement of the sliding part S. As a result, the axis of movement of the sliding part S coincides with the angle bisector between the rotation center O and the connection point o1, which is the starting point of the first link part PL1, and the connection point o4, which is the ending point of the second link part PL2.

[0034] When the first arm member M1 and the second arm member M2 rotate relative to each other around the joint J, the passive joint PJ causes the first link member PL1 and the second link member PL2 to move in conjunction with the rotational movement while maintaining a symmetrical state between them.

[0035] Furthermore, the passive joint PL is equipped with a plurality of rotating members P1 to P4 that are rotatably supported at connection points o1 to o4 from the starting point to the ending point of the link PL, respectively, as a means for changing the movement path of the linear member W, and the linear member W is stretched and supported across all of these rotating members.

[0036] Figure 6 is a schematic diagram (Figure 6(a)) and an operation diagram (Figure 6(b)) showing the state in which a linear member W is stretched across the joint mechanism shown in Figure 5. The linear member W is transported from the first arm member M1 side, stretched across the rotating members P1 to P4 attached to the passive joint PJ, and fixed to the second arm member M2. m The linear member W is guided to move along the longitudinal direction of the second arm member M2 via the linear member W. As the first arm member M1 and the second arm member M2 rotate, the passive joint PJ deforms, but the connecting points o1 to o4 and the rotating members P1 to P4 move while maintaining a symmetrical positional relationship, and the linear member W changes its movement path while maintaining a predetermined path length.

[0037] Figure 7 is a schematic diagram of another specific example of a rotating joint mechanism. The passive joint PJ comprises a link section PL in which a plurality of link members L1 to L5 are rotatably connected to each other, a support link member LS1 which is a first support section with one end fixed to a first arm member M1 and the other end rotatably connected to the end of link member L1, which is the starting point of the link section PL, and a support link member LS2 which is a second support section with the other end fixed to a second arm member M2 and the other end rotatably connected to the end of link member L5, which is the endpoint of the link section PL.

[0038] The link section PL comprises a first link section PL1 that rotatably connects link members L1 to L2 and a second link section PL2 that rotatably connects link members L4 to L5. The end of link member L2, which is the endpoint of the first link section PL1, and the end of L4, which is the starting point of the second link section PL2, are rotatably connected to each other by a link member L3, which is a mounting member to which a link connecting section LJ is attached.

[0039] Furthermore, gears G1 to G6 are pivotally supported at the connection points o1 to o6 of each link member, and each gear is of the same shape. Gear G1 is fixed to the support link member LS1, gears G2 and G3 are fixed to the link member L2, gears G4 and G5 are fixed to the link member L4, and gear G6 is fixed to the support link member LS2.

[0040] Gears G1 and G2, gears G3 and G4, and gears G5 and G6 are mounted so as to mesh with each other, and rotational movement between the link members occurs when each gear is meshed.

[0041] Link members L1 and L5, link members L2 and L4, and support link members LS1 and LS2 are all set to the same length, while link member L3 is set to a length that is half the length of gears G3 and G4 plus this length.

[0042] Therefore, the first link section PL1 and the second link section PL2 are symmetrical with respect to the straight line connecting the meshing points of gears G3 and G4 and the center of rotation O.

[0043] When the first arm member M1 and the second arm member M2 rotate relative to each other around the joint J, the passive joint PJ causes the first link member PL1 and the second link member PL2 to move in conjunction with the rotational movement while maintaining a symmetrical state between them.

[0044] Furthermore, the passive joint PJ is equipped with a plurality of rotating members P1 to P6, each pivotally supported at connection points o1 to o6 from the starting point to the ending point of the link section PL, as a means for changing the movement path of the linear member W, and the linear member W is stretched and supported across all of these rotating members.

[0045] Figure 8 is a schematic diagram showing the state in which a linear member W is stretched across the joint mechanism shown in Figure 7. The linear member W is transported from the first arm member M1 side, stretched across the rotating members P1 to P6 attached to the passive joint PJ, and fixed to the second arm member M2. mThe linear member W is guided to move along the longitudinal direction of the second arm member M2 via the linear member W. As the first arm member M1 and the second arm member M2 rotate, the passive joint PJ deforms, but the connecting points o1 to o6 and the rotating members P1 to P6 move while maintaining a symmetrical positional relationship, and the linear member W changes its movement path while maintaining a predetermined path length.

[0046] Figure 9 is a schematic diagram of a second embodiment of the joint mechanism according to the present invention. In this example, the joint mechanism 1 rotatably connects a first arm member M1 and a second arm member M2 by a joint J, and a passive joint PJ, which connects a plurality of link members, is connected between the first arm member M1 and the second arm member M2.

[0047] The first arm member M1 and the second arm member M2 are connected at their adjacent ends by a joint J, allowing them to rotate relative to each other around a rotation center O. The passive joint PJ operates in conjunction with the movements of the first arm member M1 and the second arm member M2.

[0048] The passive joint PJ comprises a link section PL that rotatably connects link members L1 and L2 to each other, a support link member LS1 which is a first support section with one end fixed to a first arm member M1 and the other end rotatably connected to the end of link member L1, which is the starting point of the link section PL, and a support link member LS2 which is a second support section with the other end fixed to a second arm member M2 and the other end rotatably connected to the end of link member L2, which is the endpoint of the link section PL.

[0049] The lengths of link members L1 and L2, and the lengths and positions of support link members LS1 and LS2 are set so that the straight line connecting the connection point o1 of link member L1, which is the starting point of the link section PL, and the connection point o3 of link member L2, which is the ending point, as well as the straight line connecting the connection point o2 of link members L1 and L2 to the rotation center O, always intersect at their midpoints. For example, if link members L1 and L2 are set to the same length, the quadrilateral with the rotation center O and connection points o1 to o3 as vertices will be a rhombus, and if they are set to different lengths, it will be a parallelogram.

[0050] Furthermore, the passive joint PL is equipped with a plurality of rotating members P1 to P3 pivotally supported at connection points o1 to o3 from the starting point to the ending point of the link PL, as a means for changing the movement path of the linear member W, which will be described later. The linear member W is stretched across all of the rotating members. The bending radii of the linear member W that wraps around the rotating members P1 and P2 are set to be equal, and the outer diameter of the linear member W that wraps around the rotating member P3 is set to be twice the bending radius of the linear member W that wraps around the rotating members P1 and P2.

[0051] Figure 10 is a schematic diagram showing a linear member W spanning the joint mechanism shown in Figure 9. The linear member W is transported from the first arm member M1 side and fixed to the first arm member M1. m1 It is wrapped around the rotating member P1 attached to the passive joint PJ, then around the outside of the rotating member P2, and then around the outside of the rotating member P3, and is stretched across each rotating member. Then, the rotating member P fixed to the second arm member M2 m2 It is guided to be transported in the longitudinal direction of the second arm member M2 via this.

[0052] When the rotary joint operates, the movement path of the linear member W along the first arm member M1 and the second arm member M2 does not change, so we only need to focus on the change in path length at the passive joint PJ. In this example, if we let A be the intersection of the line connecting the rotation center O and the connection point o1 and the path on the outer circumference of the rotary member P1, and F be the intersection of the line connecting the rotation center O and the connection point o3 and the path on the outer circumference of the rotary member P3, then the path to intersection A and the path from intersection F remain unchanged, so when considering the movement path at the passive joint, we only need to consider the path length from intersection A to intersection F.

[0053] Figure 11 is an explanatory diagram showing that the movement path of the linear member is maintained at a predetermined path length. Let B and C be the points of contact of the tangents spanning between rotating members P1 and P2, respectively, and let D and E be the points of contact of the tangents spanning between rotating members P2 and P3, respectively. In this case, the lengths of the tangents BC and DE remain constant.

[0054] When the link members move and the quadrilateral (rhombus or parallelogram) with the rotation center O and connection points o1 to o3 as vertices deforms, causing the interior angles to increase or decrease, if the increment of angle ∠Oo1o2 is Δθ, then the increments of angles ∠o2o3O and ∠o1o2o3 are Δθ and -Δθ, respectively.

[0055] Furthermore, the increment of the wrapping angle ∠Ao1B of the rotating member P1 is Δθ because it is wrapping inward, the increment of the wrapping angle ∠Co2D of the rotating member P2 is Δθ because it is wrapping outward, and the increment of the wrapping angle ∠Eo3F of the rotating member P3 is -Δθ because it is wrapping outward.

[0056] If the bending radius of rotating members P1 and P2 is r, then the bending radius of rotating member P3 is 2r, so the increase in arcs AB and CD is offset by the decrease in arc EF.

[0057] Therefore, even if the passive joint operates and the movement path of the linear members connected to each rotating member changes, the movement path will be maintained at a predetermined path length.

[0058] Figure 12 is a schematic diagram of a third embodiment of the joint mechanism according to the present invention. In this example, the joint mechanism 1 connects a first arm member M1 and a second arm member M2 so that they can move in a straight line by a joint J, and a passive joint PJ, which connects a plurality of link members, is connected between the first arm member M1 and the second arm member M2.

[0059] The first arm member M1 and the second arm member M2 are connected at their adjacent ends by a joint J, allowing them to move linearly toward each other in the longitudinal direction. The passive joint PJ is configured to operate in conjunction with the movement of the first arm member M1 and the second arm member M2.

[0060] The passive joint PJ comprises a link section PL that rotatably connects link members L1 and L2 to each other, a support link member LS1 which is a first support section with one end fixed to a first arm member M1 and the other end rotatably connected to the end of link member L1, which is the starting point of the link section PL, and a support link member LS2 which is a second support section with the other end fixed to a second arm member M2 and the other end rotatably connected to the end of link member L2, which is the endpoint of the link section PL.

[0061] Furthermore, the straight line Tp connecting the connection point o1 of link member L1, which is the starting point of the link section PL, and the connection point o3 of link member L2, which is the ending point, is set to be parallel to the straight line To that runs along the direction of straight movement of arm members M1 and M2.

[0062] Furthermore, the passive joint PL is equipped with a plurality of rotating members P1 to P3, each pivotally supported at connection points o1 to o3 from the starting point to the ending point of the link PL, as a means for changing the movement path of the linear member W, which will be described later. The linear member W is stretched and supported across all of these rotating members.

[0063] Figure 13 is a schematic diagram (Figure 13(a)) and an operation diagram (Figure 13(b)) showing a linear member spanning the joint mechanism shown in Figure 12. The linear member W is transported from the first arm member M1 side and fixed to the first arm member M1. m1 The rotating member P is wrapped around the second arm member M2, spanned across the rotating members P1 to P3 attached to the passive joint PJ, and fixed to the second arm member M2. m2 It is guided to be transported in the longitudinal direction of the second arm member M2 via this.

[0064] As the first arm member M1 and the second arm member M2 move in a straight line, the connection points o1 to o3 of the passive joint PJ move, and the rotating members P1 and P3 move along the straight line Tp while maintaining a parallel relationship with the straight line direction.

[0065] When the linear joint operates, the movement path of the linear member W along the first arm member M1 and the second arm member M2 does not change, so we only need to focus on the change in path length at the passive joint PJ. If we let A be the intersection point of the path on the outer circumference of the rotating member P1 and the straight line Tp, and F be the intersection point of the path on the outer circumference of the rotating member P3 and the straight line Tp, then the path to intersection A and the path from intersection F remain unchanged, so we only need to consider the path length from intersection A to intersection F at the passive joint PJ.

[0066] Figure 14 is an explanatory diagram showing that the movement path of the linear member W of the joint mechanism shown in Figure 12 is maintained at a predetermined path length. For the interior angles of the triangles connecting the connection points o1 to o3, respectively, ∠o2o1o3=α, ∠o1o2o3=β, and ∠o2o3o1=γ, α+β+γ=π.

[0067] If the points of contact of the tangents stretched between rotating members P1 and P2 are B and C, respectively, and the points of contact of the tangents stretched between rotating members P2 and P3 are D and E, respectively, then the wrapping angle of rotating member P1 is ∠Bo1A = π / 2 - α, the wrapping angle of rotating member P2 is ∠Co2D = π - β, and the wrapping angle of rotating member P3 is ∠Eo3F = π / 2 - γ.

[0068] The sum of each wrapping angle is (π / 2 - α) + (π - β) + (π / 2 - γ) = 2π - (α + β + γ) = π, which is constant. Therefore, when the bending radii of the linear members W that wrap around all the rotating members are equal, the length of the movement path from intersection A to intersection F is constant, and the movement path of the linear members W is maintained at a predetermined path length.

[0069] As explained above, when setting a movement path for a linear member in a joint mechanism, a passive joint is attached between the arm members of the joint mechanism and operates in conjunction with the joint movement. The movement path of the linear member can be maintained at a predetermined path length by a means for changing the linear member's path provided in the passive joint. Linear members can be applied to drive transmission members such as wires and belts, and are also useful in supply mechanisms for tape materials.

[0070] The above embodiment is applied to the joint mechanism of a robot arm, but is not limited thereto. For example, it may be applied to a guide mechanism for tape material, or as a method for extending the functionality of an existing robot.

[0071] 1...Joint mechanism, M1...First arm member, M2...Second arm member, J...Joint part, O...Center of rotation, PJ...Passive joint part, PL...Link part, PL1...First link part, PL2...Second link part, LS1...First support part, LS2...Second support part, L1-L 2n-1 ...Link members, P1 to P 2n ...Rotating member, o1 to o 2n ...Connection point

Claims

1. An articulated joint mechanism comprising a first arm member, a second arm member, an articulation portion connecting adjacent ends of the first arm member and the second arm member, and a passive articulation portion connected between the first arm member and the second arm member and operating in conjunction with the movement of the first arm member and the second arm member, wherein the passive articulation portion is supported so as to be movable in the longitudinal direction of at least a linear member stretched between the first arm member and the second arm member, and is provided with a path changing means for changing the movement path of the linear member to maintain a predetermined path length.

2. The joint mechanism according to claim 1, wherein the passive joint comprises a link portion in which a plurality of link members are rotatably connected to each other, a first support portion with one end fixed to the first arm member and the other end rotatably connected to the starting end of the link portion, and a second support portion with the other end fixed to the second arm member and the other end rotatably connected to the ending end of the link portion, the path changing means comprises a plurality of rotating members pivotally supported at each connection point from the starting end to the ending end of the link portion, and the linear member is stretched across all of the rotating members.

3. The joint portion connects the first arm member and the second arm member so that they can rotate relative to each other, and the passive joint portion comprises a link portion comprising a first link portion which connects a plurality of link members so that they can rotate relative to each other and whose starting end is rotatably connected to the first support portion, and a second link portion which connects a plurality of link members so that they can rotate relative to each other and whose ending end is rotatably connected to the second support portion, and a link connecting portion which connects the ending end of the first link portion and the starting end of the second link portion and is set to be movable along the angle bisector between a pair of straight lines connecting the rotation center of the joint portion to each other, and the joint mechanism according to claim 2, wherein the first link portion and the second link portion connect the link members so that they are symmetrical with respect to the angle bisector.

4. The joint mechanism according to claim 3, wherein the link connecting portion comprises a linear mounting member rotatably connected to the endpoint of the first link portion and the starting point of the second link portion, respectively, and a pair of gear members pivotally supported at the endpoint of the first link portion and the starting point of the second link portion, respectively, and set to be symmetrical with respect to the line bisector.

5. The joint portion connects the first arm member and the second arm member so that they can rotate relative to each other, and the link portion comprises a first link member with one end rotatably connected to the first support portion, and a second link member with one end rotatably connected to the first link member and the other end rotatably connected to the second support portion, and the joint mechanism according to claim 2 is set such that the line connecting the connection point of the first link member and the second link member and the rotation centers of the first arm member and the second arm member intersects at the midpoint of the line connecting the start point and the end point of the link portion.

6. The joint mechanism according to claim 2, wherein the joint connects the first arm member and the second arm member so that they can move relative to each other in a straight line direction, and the passive joint is set such that the straight line connecting the starting point and the ending point of the link is parallel to the straight line direction.

Images