JP2016078160A - Robot arm mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize dissolution of interference between an electric cable and a peripheral component or the like, breakage of an interfered component, rupture of the electric cable and so on, and further, to realize downsizing of a storage space for the electric cable.SOLUTION: A robot arm mechanism is characterized by including: a stem 1; a robot arm part 2 which is attached to the stem 1 and has a direct-acting joint; a telescopic cable 30 which supplies at least one of an electric power and a signal to a tip part of the robot arm part 2 and has an elastic property; plural cable guides 51 which guide the telescopic cable 30 from a cable stationery part 33a on the tip part side to a cable stationery part 33b on the stem side; and a route extension part 40 which is interposed on a wiring path in order to extend the wiring path configured from the plural cable guides 51 from the tip part side cable stationery part 33a to the stem side cable stationery part 33b.SELECTED DRAWING: Figure 3

Description

  Embodiments described herein relate generally to a robot arm mechanism.

  Conventionally, articulated arm mechanisms have been used in various fields such as industrial robots. As the joints equipped in the arm mechanism, a torsional joint, a bending joint, and a linear motion joint are combined. In particular, in an articulated arm mechanism having a linear motion joint, an electric cable is accommodated in a telescopic shaft case extending in the telescopic shaft direction. As an electric cable, generally, a harness in which a plurality of electric wires are bundled or a covered wiring that is an aggregate of a plurality of wires is used. In this case, an extra length is given to the electric cable in advance in consideration of the expansion and contraction operation of the robot.

  Providing the extra length in the electric cable may cause interference with surrounding parts, damage to the interfered parts, breakage of the electric cable, etc. due to the slack. Furthermore, an accommodation space for accommodating the extra length of the electric cable is required inside the arm mechanism.

  The purpose is to reduce the interference between the electrical cable and the surrounding parts, damage to the interfered parts, breakage of the electrical cable, etc., and further reduce the accommodation space of the electrical cable.

  A robot arm mechanism according to an embodiment includes a base, an arm having a linear joint attached to the base, and a stretchable cable for supplying at least one of electric power and a signal to a tip portion of the arm. A cable guide for guiding the cable from the cable fixing portion on the distal end side to the base side cable fixing portion, and a wiring path by the cable guide from the cable fixing portion on the distal end portion side to the base side cable fixing portion In order to extend the distance, a path extension portion interposed on the wiring path is provided.

FIG. 1 is an external perspective view of a robot arm mechanism according to the present embodiment. FIG. 2 is a diagram showing an internal structure of the robot arm mechanism of FIG. FIG. 3 is a view of the internal structure of the robot arm mechanism of FIG. 1 as viewed from the cross-sectional direction. FIG. 4 is a view showing the structure of the first connected top row that constitutes the linear motion expansion joint of the robot arm mechanism according to the present embodiment. FIG. 5 is a diagram illustrating an example of the structure of the path extension portion of FIG. 3. FIG. 6 is a supplementary explanatory diagram for explaining a method for determining the total length of the telescopic cable used in the robot arm mechanism of the present embodiment. FIG. 7 is a supplementary explanatory diagram for explaining the wiring path length extended by the path extension portion of FIG. 3. FIG. 8 is a diagram illustrating an example of the structure of the path extension portion according to the first modification. FIG. 9 is a diagram illustrating an example of the structure of the path extension portion according to the second modification.

  Hereinafter, the robot arm mechanism according to the present embodiment will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  FIG. 1 is an external perspective view of a robot arm mechanism according to the present embodiment. 2 and 3 show the internal structure of the robot arm mechanism. The robot arm mechanism has a base 1 and a robot arm 2. A hand effector 3 called an end effector is attached to the tip of the robot arm unit 2. In FIG. 1, a hand unit 16 capable of gripping an object is illustrated as the hand effector 3. The hand effector 3 is not limited to the hand unit 16 and may be another tool, a sensor, a camera, or a display. An adapter that can be replaced with any kind of hand effector 3 may be provided at the tip of the robot arm unit 2.

  The robot arm unit 2 has a plurality of joints J1, J2, J3, J4, J5, and J6. The plurality of joint portions J1, J2, J3, J4, J5, and J6 are sequentially arranged from the base portion 1. At least one of the plurality of joint portions J1, J2, J3, J4, J5, and J6 is a linear joint. Here, the third joint portion J3 is configured as a linear motion joint, particularly as a linear motion telescopic joint. The first joint portion J1 is a torsional rotary joint centered on the first rotation axis RA1. The second joint portion J2 is a bending rotation joint centered on the second rotation axis RA2 arranged in a direction orthogonal to the first rotation axis RA1. The third joint portion J3 is a linear motion expansion / contraction joint that linearly expands and contracts around the third movement axis RA3 arranged in a direction orthogonal to the second rotation axis RA2. The fourth joint portion J4 is a torsional rotary joint centered on the fourth movement axis RA4 coinciding with the third movement axis RA3, and the fifth joint portion J5 is arranged in a direction orthogonal to the fourth rotation axis RA4. This is a bending rotary joint with the fifth rotation axis RA5 as the center. The sixth joint portion J6 is a bending rotation joint centered on the sixth rotation axis RA6 arranged in a direction orthogonal to the fifth rotation axis RA5. In general, the first, second, and third axes RA1, RA2, and RA3 are called the root three axes that change the position of the hand unit 16, and the fourth, fifth, and sixth axes RA4, RA5, and RA6 are the hands. This is referred to as a wrist three axis that changes the posture of the unit 16. The robot arm part 2 turns together with the hand part 16 by the torsional rotation of the first joint part J1. By bending and rotating the second joint portion J2, the robot arm portion 2 rotates together with the hand portion 16 around the second rotational axis RA2 of the second joint portion J2 in the direction of the first rotational axis RA1 of the first joint portion J1, for example, vertically. Move.

  The arm support body (first support portion) 11a forming the base portion 1 has a cylindrical hollow structure formed around the rotation axis RA1 of the first joint portion J1. The first joint portion J1 is attached to a fixed base (not shown). When the first joint portion J <b> 1 rotates, the first support portion 11 a rotates with the turning of the robot arm portion 2. In addition, the 1st support part 11a may be fixed to the grounding surface. In that case, it is provided in a structure in which the robot arm portion 2 turns independently of the first support portion 11a. The second support part 11b is connected to the upper part of the first support part 11a.

  The second support portion 11b has a hollow structure that is continuous with the first support portion 11a. One end of the second support portion 11b is attached to the rotating portion of the first joint portion J1. The other end of the second support portion 11b is opened, and the third support portion 11c is rotatably fitted on the rotation axis RA2 of the second joint portion J2. The 3rd support part 11c has a scale-like hollow structure connected to the 1st support part 11a and the 2nd support part. The third support portion 11c is accommodated in the second support portion 11b and sent out as the second joint portion J2 is bent and rotated. The rear part of the third joint part J3 constituting the linear motion joint of the robot arm part 2 is housed in the hollow structure in which the first support part 11a, the second support part 11b, and the third support part 11c are continuous by contraction. .

  The first joint portion J1 includes an annular fixed portion and a rotating portion, and is fixed to the pedestal at the fixed portion. The first support part 11a and the second support part 11b are fixed to the rotating part. When the first joint portion J1 rotates, the first, second, and third support portions 11a, 11b, and 11c rotate together with the robot arm portion 2 and the hand portion 16 about the first rotation axis RA1.

  The third support portion 11c is fitted to the lower end portion of the second support portion 11b so as to be rotatable about the rotation axis RA2 at the lower end portion of the second support portion 11b. Thus, a second joint portion J2 is formed as a bending joint with the rotation axis RA2 as the center. When the second joint portion J2 rotates, the third support portion 11c rotates together with the robot arm portion 2 and the hand portion 16 in the vertical direction around the rotation axis RA2 of the second joint portion J2. The rotation axis RA2 of the second joint portion J2 is provided in a direction orthogonal to the first rotation axis RA1 of the first joint portion J1 as a torsional rotation joint.

  As described above, the third joint portion J3 serving as the linear motion expansion / contraction joint constitutes a main component of the robot arm portion 2. The above-described hand unit 16 is provided at the tip of the robot arm unit 2. It is possible to arrange the hand portion 16 in an arbitrary position / posture by rotation, bending, and expansion / contraction of the first to sixth joint portions J1-J6. In particular, the length of the linear motion expansion / contraction distance of the third joint portion J3 enables the hand portion 16 to act on a wide range of objects from the proximity position of the base 1 to the remote position.

  This embodiment is characterized by the length of the linear motion extension / contraction distance realized by the linear motion extension / contraction arm mechanism constituting the third joint portion J3. The length of the linear expansion / contraction distance is achieved by the structure shown in FIGS. The direct acting telescopic arm mechanism has a first connecting frame row 21 and a second connecting frame row 20. In the reference posture in which the robot arm unit 2 is horizontally disposed, the first connection frame row 21 is positioned below the second connection frame row 20 and the second connection frame row 20 is positioned above the first connection frame row 21. To do.

  As shown in FIG. 4, the first connecting frame rows 21 have the same U-shaped cross-section, can be bent in the back direction BD, and cannot be bent in the surface direction FD. It consists of a plurality of first connecting pieces 23 to be connected. The first connection frame row 21 has a continuous groove shape. It can be used as a useful space for passing an electric cable in the groove shape, and a plurality of cable guides 51 are provided in a row on the inner surface of the first connecting piece 23. The 2nd connection top row | line | column 20 has a substantially flat plate shape, and consists of the some 2nd connection top | top | piece 22 connected in a row | line | column shape in the state which can be bent in a back direction.

  The first linked frame row 21 is connected to the second linked frame row 20 by a connecting piece 26 at the tip. The connecting piece 26 has a shape in which the first connecting piece 23 and the second connecting piece 22 are integrated. When the robot arm unit 2 is extended, the connecting piece 26 becomes the starting end, and the connecting piece 22 and the connecting piece 23 are connected to form one rigid body. When the first connection piece row 21 and the second connection piece row 20 are joined, the bending of the first connection piece row 21 is restricted by the second connection piece row 20, and the restriction of the bending is released by separation. The 1st connection top row | line | column 21 and the 2nd connection top row | line | column 20 are joined from the 3rd support part 11c, and are sent out. When the first connection frame row 21 and the second connection frame row 20 are accommodated in the second support portion 11b and the first support portion 11a, they are separated from each other in the third support portion 11c.

  As shown in FIG. 2, a linear gear 22 a is formed inside each connecting piece 22. The linear gear 22a forms a continuous gear when the connected upper connecting pieces 22 are linear, and the drive gear 24a fixed in position in the third support portion 11c meshes as shown in FIG. When the drive gear 24a rotates forward by the motor M1, the second connecting piece row 20 is sandwiched between the first connecting piece row 21 and the upper and lower rollers R1, R2, and R4 from the third support portion 11c, and is pressed against and joined to each other. In this state, it is sent out linearly along the third axis RA3. When the drive gear 24a is reversely rotated by the motor M1, the second connected top row 20 and the first connected top row 21 are released from the joined state by the upper and lower rollers R1, R2, R4, separated, and bendable. The three support portions 11c to the second support portion 11b and the first support portion 11a are accommodated.

  The hand unit 16 is disposed at the tip of the robot arm unit 2 as shown in FIG. The hand portion 16 can be arranged in an arbitrary posture by the fourth joint portion J4, the fifth joint portion J5, and the sixth joint portion J6. The hand portion 16 has two finger portions 16a and 16b that are opened and closed. The fourth joint portion J4 is a rotary joint having a rotation axis RA4 that typically coincides with the central axis of the robot arm portion 2 along the expansion / contraction direction of the robot arm portion 2, that is, the movement axis RA3 of the third joint portion J3. is there. When the fourth joint portion J4 rotates, the hand portion 16 twists and rotates about the rotation axis RA4 from the fourth joint portion J4 to the tip.

  The fifth joint portion J5 is a bending joint having a rotation axis RA5 orthogonal to the movement axis (arm axis) RA3 of the third joint portion J3 as a linear motion expansion / contraction joint. When the fifth rotary joint rotates, it rotates up and down together with the hand portion 16 from the fifth joint portion J5 to the tip. The sixth joint portion J6 is a bending rotary joint having a rotation axis RA6 orthogonal to the movement axis (arm axis) RA3 of the third joint portion J3 and the rotation axis RA5 of the fifth joint portion J5 as a linear motion telescopic joint. It is. When the sixth joint portion J6 rotates, the hand portion 16 turns left and right.

  As shown in FIG. 3, the wiring mechanism of the extension cable 30 includes the extension cable 30, a plurality of cable guides 51, a path extension 40, a hand part side cable fixing part 33 a, and a base side cable fixing part 33 b. Composed.

  The elastic cable 30 is composed of a plurality of types of transmission lines having elasticity. For example, the transmission line includes a power transmission line for transmitting current, an electrical signal transmission line for transmitting electrical signals, an optical transmission line for transmitting light, and an optical signal transmission line for transmitting optical signals. The stretchable cable 30 is configured by combining these transmission lines according to the application and the like. The stretchable cable 30 according to the present embodiment includes a power transmission line that transmits current and an electrical signal transmission line that transmits electrical signals. The power transmission line having elasticity is, for example, a copper wire or an aluminum wire spirally wound around an elastic body. The electric signal transmission line having elasticity is, for example, one in which two or more conductor lines are wound around the elastic body in the same direction. The stretchable electric signal transmission line may be one in which two or more conductor wires are wound around the elastic body.

  One end of the elastic cable 30 is connected to a motor driver 31 that controls a motor for opening and closing the hand portion 16. The other end is connected to a connector of an external power source that generates power and a connector of an external control device that generates a control signal. The motor driver 31 generates a driving pulse for driving the motor using the power input from the power source via the telescopic cable 30 in accordance with a control signal from the control device. The motor rotates according to the drive pulse supplied from the motor driver 31. When the motor rotates, the hand unit 16 is opened and closed via a gear (not shown) connected to the drive shaft of the motor.

  One end portion of the extension cable 30 is fixed to a cable fixing portion 33a (hereinafter referred to as a hand portion side cable fixing portion 33a) provided immediately before the motor driver 31 in the hand portion 16. The other end portion of the elastic cable 30 is fixed to a cable fixing portion 33b (hereinafter referred to as a base side cable fixing portion 33b) provided at the bottom position in the base portion 1. Thereby, even if the tension | tensile_strength is applied to the expansion-contraction cable 30, the risk of disconnection, such as the expansion-contraction cable 30 coming out of a connector, can be reduced. A portion between the hand portion side cable fixing portion 33 a and the base portion side cable fixing portion 33 b of the extension cable 30 is guided by a plurality of cable guides 51. The plurality of cable guides 51 form a wiring path for the telescopic cable 30. The cable guide 51 has, for example, a ring structure having a circular arc cross section. The stretchable cable 30 is held so as to be stretchable by passing through the ring.

  The path extension 40 is interposed on the wiring path of the telescopic cable 30 in order to extend the wiring path from the hand side cable fixing part 33a to the base side cable fixing part 33b. The structure of the path extension 40 will be described with reference to FIG.

  FIG. 5 is a diagram showing an example of the structure of the path extension 40 of FIG. The path extension 40 includes a plurality of pulleys having the same radius r, here, a first pulley 41, a second pulley 42, and a third pulley 43. Each of these pulleys 41, 42, and 43 is dispersedly arranged in a direction substantially parallel to the axis (Z axis) of the first support portion 11a. For example, the pulleys 41 and 42 are disposed at the same position with respect to the Z axis. The pulley 43 is disposed below the pulleys 41 and 42 at a predetermined distance. The pulley 41 is disposed such that the rotation axis Rx1 thereof is parallel to the second rotation axis RA2 (X axis) of the second joint portion J2. The pulleys 42 and 43 are arranged so that the respective rotation axes Rx2 and Rx3 are parallel to the rotation axis Rx1 of the pulley 41. The pulley 41 is arranged at a distance shorter than the radius r1 along the Y axis perpendicular to the X axis and the Z axis with respect to the pulley 42. The pulley 43 is disposed at the center position between the pulley 41 and the pulley 42 in the Y-axis direction. The stretchable cable 30 is stretched over the pulley 41, the pulley 43, and the pulley 42 in this order. As a result, the plurality of pulleys 41, 42, 43 form a reciprocating wiring path along the axial direction of the first support portion 11a for the telescopic cable 30. The reciprocating wiring path extends a wiring path formed only by the plurality of cable guides 51 arranged between the hand part side cable fixing part 33a and the base part side cable 33b. Thereby, the total length of the elastic cable 30 is extended from the total length of the elastic cable 30 guided only by the plurality of cable guides 51.

  The path extension 40 is provided with a pulley 44. The pulley 44 is disposed such that the rotation axis Ry is orthogonal to the rotation axis Rx2 of the pulley 42 and the central axis of the first support portion 11a. As for the arrangement of the pulley 44, the telescopic cable 30 is pulled out from the vicinity of the central axis of the first support portion 11a to the pulley 42 along the radial direction thereof.

  Specifically, as shown in FIG. 5, the rotation axis Ry of the pulley 44 is orthogonal to the rotation axes Rx1, Rx2, and Rx3 of the other pulleys 41, 42, and 43. The pulley 44 is arranged offset in the X-axis direction with respect to the YZ plane on which the other pulleys 41, 42, and 43 are arranged. As a result, the pulley 44 moves the stretchable cable 30 guided by being offset in the X-axis direction from the YZ plane on which the other pulleys 41, 42, 43 are arranged, and the YZ plane on which the other pulleys 41, 42, 43 are arranged. Therefore, it is possible to secure a wiring path portion for guiding.

  In addition, the structure of the path | route extension part 40 is not limited to the mechanism illustrated in FIG. The number of pulleys, the distance between the pulleys, and the orientation of each pulley depend on the total length of the stretchable cable 30, the volume that can be occupied as the path extension 40, the positional relationship between the base cable fixing portion 33b and the cable guide 51, etc. Changes can be made accordingly. For example, each of the pulleys 41, 42, 43 may be disposed in a positional relationship for forming a wiring path necessary for reciprocating the telescopic cable 30 along a direction orthogonal to the axial direction of the first support portion 11a. Good.

  Further, the pulleys 41, 42, and 43 may be arranged such that their respective rotation axes are substantially parallel to a radial direction centered on the axis of the first support portion 11a. Accordingly, since each of the pulleys 41, 42, and 43 can be arranged on a circumference centered on the axis of the first support portion 11a, in the case of the base portion 1 having a cylindrical shape or the like, the path into the base portion 1 The degree of freedom of arrangement of the extension 40 can be improved.

Next, a method for determining the total length of the elastic cable 30 will be described with reference to FIG.
FIG. 6 is a supplementary explanatory diagram for explaining a method for determining the total length of the telescopic cable 30 used in the robot arm mechanism of the present embodiment. As shown in FIG. 6, when the arm is contracted, the shortest wiring path length from the hand part side cable fixing part 33a to the base part side cable fixing part 33b in the case of being formed by only the plurality of cable guides 51 is the shortest path length Lc1. And When the arm is contracted, the linear motion expansion / contraction distance of the linear motion joint J3 is zero, that is, the state where the robot arm unit 2 is contracted most. On the other hand, the shortest wiring path length from the hand part side cable fixing part 33a to the base part side cable fixing part 33b in the case of forming with only a plurality of cable guides 51 when the arm is extended is defined as the shortest path length Lc2. When the arm is extended, it means that the linear motion joint J3 is extended to the maximum of the linear motion expansion / contraction distance. A difference between the longest path length Lc2 and the shortest path length Lc1 is defined as an expansion / contraction length Δdc1.

The total length Lw1 of the expansion cable 30 at the time of contraction has a length necessary for securing an expansion / contraction length that is equal to or greater than the expansion / contraction length Δdc1. Specifically, the total length Lw1 of the telescopic cable 30 at the time of contraction may be determined as follows. When the expansion / contraction ratio of the expansion / contraction cable 30 is the expansion / contraction ratio α, the following formula (1) is established between the total length Lw1, the expansion / contraction ratio α, and the expansion / contraction length Δdc1 of the expansion / contraction cable 30 when contracted. That is, the expansion / contraction length Δdc1 must be equal to or less than the length obtained by multiplying the total length Lw1 of the expansion cable 30 at the time of contraction by the expansion / contraction rate α.
Δdc1 ≦ Lw1 × α (1)
Therefore, the total length Lw1 of the expansion cable 30 at the time of contraction needs to satisfy the following formula (2).
Lw1 ≧ Δdc1 / α (2)
Further, since the path extension portion 40 of the robot arm mechanism according to the present embodiment forms a reciprocal wiring path, d1> 0. The length (extension cable length) d1 of the extended portion of the wiring path extended by the path extension 40 is substantially equivalent to the difference between the shortest path length Lc1 and the total length Lw1 of the telescopic cable 30 when contracted. That is, the total length Lw1 of the stretchable cable 30 at the time of contraction needs to satisfy the following formula (3). From equation (3), it can be seen that the total length Lw1 of the telescopic cable 30 at the time of contraction must be longer than the shortest path length Lc1.
Lw1> Lc1 (3)
Moreover, it is suitable for the expansion-contraction cable 30 that the full length Lw1 of the expansion-contraction cable 30 at the time of contraction is shorter than the longest path | route length Lc2. Therefore, the total length Lw1 of the elastic cable 30 at the time of contraction needs to satisfy the following formula (5).

Lw1 <Lc2 (4)
From Expression (2), Expression (3), and Expression (4), when the expansion cable 30 at the time of contraction has an expansion ratio α satisfying Expression (5), the expansion cable 30 full length Lw1 at the time of contraction is determined as the longest path. The length can be shorter than the length Lc2.

Δdc1 / Lc2 <α <Δdc1 / Lc1 (5)
Therefore, if the expansion / contraction cable 30 according to the present embodiment is determined so that the expansion / contraction ratio α satisfies Expression (5) and the total length Lw1 of the expansion / contraction cable 30 at the time of contraction satisfies Expression (3) and Expression (4). Good. As a result, the difference between the total length Lw1 ′ of the expansion cable 30 at the time of expansion and the total length Lw1 of the expansion cable 30 at the time of contraction is equal to or greater than the expansion length Δdc1. The expansion / contraction length can be ensured. Conventionally, when a cable having no elasticity is used, the total length of the cable needs to be equal to or longer than the longest path length Lc2. On the other hand, in the present embodiment, the total length Lw1 of the telescopic cable 30 at the time of contraction can be made shorter than the longest path length Lc2. As a result, the accommodation space for the elastic cable 30 in the path extension 40 can be reduced.

  In addition, this embodiment does not deny the use of the expansion / contraction cable 30 having an expansion / contraction ratio α equal to or lower than the lower limit expansion / contraction ratio (Δdc1 / Lc2) in the range of the formula (5). In this case, it may be unavoidable that the total length Lw1 of the telescopic cable 30 at the time of contraction is longer than the longest path length Lc2. However, the options for the telescopic cable 30 can be expanded. For example, it may be possible to select a type of stretchable cable in which more electric wires are braided or a stretchable cable having a waterproof function.

  In the above description, it has been described that it is preferable that the length Lw1 when the expansion cable 30 is contracted does not exceed the longest path length Lc2. However, this embodiment does not deny that the length Lw1 when the expansion cable 30 is contracted is long enough to exceed the longest path length Lc2. By using a part of the maximum expansion / contraction length determined by the expansion / contraction ratio (inherent expansion / contraction ratio) possessed by the expansion / contraction cable 30 and the total length Lw1, the expansion / contraction length Δdc1 required for the structure can be secured. In this case, the shrinkage ratio (practical stretch ratio) in use can be kept lower than the intrinsic stretch ratio. In this way, in terms of mounting, it is suggested that expanding / contracting the expansion / contraction cable 30 with a practical expansion / contraction ratio lower than the intrinsic contraction ratio may have an effect of improving the durability of the expansion / contraction cable 30. Furthermore, the tension applied to the stretchable cable 30 when the stretchable cable 30 is stretched at a practical stretch rate lower than the intrinsic shrinkage rate to secure the stretch length Δdc1 required for the structure is mounted. Can be kept lower than the tension applied to the extension cable 30 when securing the extension length Δdc1 required for the structure, thereby reducing the load on the structure and driving when the robot arm mechanism is extended and contracted. This suggests the possibility of reducing the effect.

  Next, the total length of the wiring route extended by the route extension 40 will be described with reference to FIG.

  FIG. 7 is a supplementary explanatory diagram for explaining the wiring path length extended by the path extension unit 40 of FIG. 3. The total length of the wiring path extended by the path extension 40 when the arm contracts is the total length Lw1 of the expansion cable 30 at the time of contraction required to secure an expansion / contraction length of Δdc1 or more as described in FIG. Is approximately equivalent to Actually, it is preferable that the total length of the wiring path extended by the path extension portion 40 is slightly shorter than the total length Lw1 of the expansion / contraction cable 30 at the time of contraction, which is necessary for securing an expansion / contraction length of Δdc1 or more. is there. Thereby, even when the arm contracts, a slight tension is applied to the stretchable cable 30 spanned by the plurality of pulleys 41-44 constituting the path extending portion 40, so that the stretchable cable 30 can be prevented from sagging. The total length Lw1 of the stretchable cable 30 used in this embodiment is longer than the shortest path length Lc1 by a length d1. Therefore, the path extension 40 interposed on the wiring path constitutes the reciprocal wiring path described in FIG. 5, for example, in order to secure a wiring path for the extra length d1 of the telescopic cable 30. Thereby, the path extension unit 40 extends the entire length of the wiring path from the shortest path length Lc1 to Lw1 (Lc1 + d1). By routing the stretchable cable 30 satisfying the expression (4) along the wiring route extended by the route extending portion 40, the total length of the stretchable cable 30 at the time of extension becomes Lw1 ′ or more, and the stretchable length Δdc1 can be secured.

According to the robot arm mechanism according to the present embodiment described above, the following effects can be obtained.
The stretchable cable 30 according to the present embodiment has a total length necessary for securing the stretchable length Δdc1 when the cable is contracted. The total length Lw1 of the retractable expansion cable 30 thus secured is longer than the shortest path length Lc1. Therefore, the path extension unit 40 according to the present embodiment has a function of extending the wiring path and a function of accommodating the telescopic cable 30. The path extension 40 is configured such that the total length of the wiring path when the arm contracts is substantially equivalent to the total length Lw1 of the telescopic cable 30 when contracted. As a result, the entire length of the wiring path extended by the path extending portion 40 is extended by the length d1 as compared with the wiring path formed by only the plurality of cable guides 51. Thus, even when the arm contracts, the extension cable 30 is accommodated in the path extension 40 without sagging, so that the extension cable 30 does not interfere with surrounding parts and the like during the extension / contraction operation of the robot arm 2. As a result, breakage of parts, breakage of the extension cable 30 and the like can be solved. In addition, it is preferable that the total length of the wiring path extended by the path extension unit 40 when the arm contracts is slightly shorter than the total length Lw1 of the telescopic cable 30 when contracted. As a result, even when the arm is contracted, a slight tension is applied to the stretchable cable 30 delivered to the plurality of pulleys constituting the path extension portion 40, thereby preventing the stretchable cable 30 from sagging at the path extension portion 40. it can.

  The path extension 40 has a mechanism in which a plurality of pulleys 41, 42, and 43 are arranged so as to form a reciprocal wiring path along the axial direction of the first support 11 a. However, the number of pulleys, the distance between the pulleys, and the orientation of each pulley are the total length of the telescopic cable 30, the volume that can be occupied as the path extension 40, and the positional relationship between the base-side cable fixing portion 33b and the cable guide 51. It suffices to be configured according to the above. Therefore, the path extension part 40 according to the present embodiment can reduce the accommodation space of the elastic cable 30. In addition, by using a rotatable pulley for the path extension portion 40, the pulley functions as an extension part for the extension cable 30 and a retracting part for the extension part. Friction generated between the portion 40 and the telescopic cable 30 can be reduced.

(Modification 1)
The robot arm mechanism according to the first modification of the present embodiment has a path extension 40 that is different from the robot arm mechanism according to the present embodiment. Hereinafter, the path extension unit 40 of the robot arm mechanism according to the first modification of the present embodiment will be described with reference to FIG.
FIG. 8 is a diagram illustrating an example of the structure of the route extension 40 according to the first modification. Fig.8 (a) is a front view which shows an example of the structure of the path | route extension part 40 which concerns on a 1st modification. FIG. 8B is a side view of FIG. 8A and corresponds to the time when the arm contracts. FIG. 8B is a side view of FIG. 8A and corresponds to when the arm is extended.

  As shown in FIG. 8A, the path extension 40 according to the first modification has a spool 55 around which the telescopic cable 30 is wound. When the telescopic cable 30 is wound around the spool 55, the path extension unit 40 according to the first modification can extend the wiring path. As shown in FIG. 8B and FIG. 8C, the number of turns of the elastic cable 30 wound around the spool 55 is the same when the arm is contracted and when the arm is extended. As shown in FIG. 8B, the spool 55 has a mechanism for preventing the stretchable cables 30 wound around the spool 55 from contacting each other. For example, the spool 55 is formed with a guide groove 57 that prevents the elastic cables 30 from coming into contact with each other. By winding the stretchable cable 30 along the guide groove 57, adjacent stretchable cable portions do not come into contact with each other, so that friction between stretchable cable portions that expand and contract in the opposite direction due to stretching can be suppressed. The spool 55 is supported so as to be rotatable about the base 1. As a result, the spool 55 freely rotates in accordance with the expansion and contraction of the expansion cable 30, and therefore the friction between the spool 55 and the expansion cable 30 can be reduced. As a result, the risk of disconnection of the elastic cable 30 is reduced. Due to these effects, the risk of breakage of the elastic cable 30 can be reduced.

  The path extension 40 according to the modified example 1 described above is similar to the path extension 40 according to the present embodiment by using the spool 55 as an alternative to the plurality of pulleys of the path extension 40 according to the present embodiment. The effect can be obtained.

(Modification 2)
The path extension part 40 of the robot arm mechanism according to the second modified example of the present embodiment is configured by a plurality of pulleys similarly to the path extension part 40 of the robot arm mechanism according to the present embodiment. The difference from the present embodiment is that the path extension 40 according to the second modification has a function of securing a substantial extension / contraction length of the extension / contraction cable 30. Hereinafter, the path extension 40 of the robot arm mechanism according to the second modification of the present embodiment will be described with reference to FIG.
FIG. 9 is a diagram illustrating an example of the structure of the route extension 40 according to the second modification. Fig.9 (a) is a front view which shows an example of the structure of the path | route extension part 40 which concerns on a 2nd modification, and respond | corresponds at the time of arm contraction. FIG. 9B is a front view showing an example of the structure of the path extension 40 according to the second modified example, and corresponds to when the arm is extended.

  The path extension 40 includes a plurality of pulleys having the same radius, here, a first pulley 59 and a second pulley 61. These pulleys 59 and 61 are urged by urging mechanisms 63 and 65 in a direction substantially parallel to the axis (Z axis) of the first support portion 11a. As shown in FIG. 9, for example, a biasing spring is used for the biasing mechanism. The urging mechanism may be another mechanism as long as urging is possible. For example, the urging mechanism may be a nesting type, a bellows type, a rubber type, or the like. Each of these pulleys 59 and 61 is dispersedly arranged in a direction substantially parallel to the axis (Z axis) of the first support portion 11a. The pulley 59 is disposed below the pulley 61 at a predetermined distance. The pulleys 59 and 61 are arranged so that the respective rotation axes are parallel to the second rotation axis RA2 (X axis) of the second joint portion J2. Accordingly, the plurality of pulleys 59 and 61 form a reciprocal wiring path for the telescopic cable 30 along the axial direction of the first support portion 11a. The reciprocating wiring path extends a wiring path formed only by the plurality of cable guides 51 arranged between the hand part side cable fixing part 33a and the base part side cable 33b. Thereby, the total length of the elastic cable 30 is extended from the total length of the elastic cable 30 guided only by the plurality of cable guides 51.

The path extension 40 according to the second modification has a function of securing a substantial cable expansion / contraction length. Specifically, the length of the extension part extended by the path extension part 40 differs before and after the extension of the telescopic cable 30. As shown in FIG. 9A, the urging spring is in a contracted state when the arm contracts. On the other hand, as shown in FIG. 9B, when the arm is extended, tension is generated in the telescopic cable 30 in the axial direction of the first support portion 11a, and the biasing spring is in the axial direction of the first support portion 11a. Is expanded. At this time, the extension of the biasing spring is Δd11. Then, the length of the extension portion extended by the path extension portion 40 when the arm is extended is shorter by 2 × Δd11 than when the arm is contracted. The extension (2 × Δd11) of the biasing spring of the path extension 40 when the arm is extended is applied to the expansion / contraction length Δdc1. That is, in this embodiment, it is necessary to ensure the expansion / contraction length Δdc1 only by expansion / contraction of the expansion / contraction cable 30. However, in the second modification, the expansion / contraction of the expansion / contraction cable 30 and the expansion / contraction of the extension part of the wiring path of the path extension 40 are provided. Thus, the expansion / contraction length Δdc1 can be ensured. Thereby, in addition to the effect of this embodiment, the robot arm mechanism according to the second modification shortens the total length of the extension cable 30 to be used by the extension of the biasing spring, as compared with the robot arm mechanism of this embodiment. be able to. Further, the robot arm mechanism according to the modification 2 can absorb the tension by the biasing spring when the tension in the axial direction of the first support portion 11a is generated in the telescopic cable 30. Therefore, the robot arm mechanism according to the modified example 2 can reduce the burden on the extension cable 30 as compared with the robot arm mechanism of the present embodiment.
Note that the structure of the path extension 40 shown in FIG. 9 can also be applied when the hand portion side cable fixing portion 33a and the base portion side cable fixing portion 33b are wired with a non-stretchable cable. For example, the total elongation of the two biasing springs may be equal to or greater than the expansion / contraction length Δdc1. Thereby, even if it does not use the expansion-contraction cable 30, the expansion-contraction length (DELTA) dc1 is securable only by extension of a biasing spring.

  Moreover, it is not limited to the mechanism illustrated in FIG. The number of pulleys, the distance between the pulleys, and the orientation of each pulley depend on the total length of the stretchable cable 30, the volume that can be occupied as the path extension 40, the positional relationship between the base cable fixing portion 33b and the cable guide 51, etc. Changes can be made accordingly. For example, the plurality of pulleys may be arranged in a positional relationship for forming a wiring path necessary for reciprocating the telescopic cable 30 along a direction orthogonal to the axial direction of the first support portion 11a.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and spirit of the invention, and are also included in the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Base part, 2 ... Robot arm part, 3 ... Hand effector, 11a ... 1st support part, 11b ... 2nd support part, 11c ... 3rd support part, J1, J2, J3, J4, J5, J6 ... Joint , 16... Hand part, 20... Second connection frame row, 21... First connection frame row, 22... Second connection frame, 22 a... Linear gear, 23. 30 ... telescopic cable, 31 ... motor driver, 33a ... hand side cable fixing part, 33b ... base side cable fixing part, 40 ... path extension part, 41, 42, 43, 44 ... pulley, 51 ... cable guide, M1 ... Motor, R1, R2, R4 ... Upper and lower rollers, RA1, RA2, RA4, RA5, RA6 ... Rotating shaft, RA3 ... Moving shaft

Claims (12)

The base,
An arm having a linear motion joint attached to the base;
A cable having elasticity for supplying at least one of electric power and signal to the tip portion of the arm;
A cable guide for guiding the cable from the cable fixing portion on the tip portion side to the base side cable fixing portion;
A robot arm mechanism comprising: a path extension portion interposed on the wiring path to extend a wiring path by the cable guide from the cable fixing section on the distal end portion side to the base side cable fixing section.   The total length of the wiring path extended by the path extension portion is approximately equivalent to the cable length when the cable is contracted, which is required to secure the expansion / contraction distance of the linear motion joint by expansion / contraction of the cable. The robot arm mechanism according to claim 1, wherein:   The length of the extended portion of the wiring path extended by the path extending portion is substantially equivalent to the difference between the length of the wiring path by the cable guide and the cable length when the cable is contracted. 2. The robot arm mechanism according to 2.   2. The robot arm mechanism according to claim 1, wherein the cable has a cable length at the time of contraction required to secure an extension / contraction length of the cable more than an extension / contraction distance of the linear motion joint.   5. The robot arm mechanism according to claim 4, wherein the cable length at the time of contraction is substantially equivalent to the entire length of the wiring path extended by the path extension portion when the linear motion joint contracts.   The robot arm mechanism according to claim 1, wherein the path extension portion includes a plurality of pulleys around which the cable is stretched.   7. The robot arm mechanism according to claim 6, wherein the plurality of pulleys are arranged in a positional relationship for forming a wiring path necessary for reciprocating the cable along the axial direction of the base.   8. The robot arm mechanism according to claim 7, wherein the path extension portion has another pulley for securing a wiring path portion in a direction substantially orthogonal to the axial direction of the base portion.   The plurality of pulleys have the same radius, and some of the plurality of pulleys are arranged at the same position with respect to the axial direction, and the plurality of pulleys arranged at the same position are at a distance shorter than the radius from each other. The robot arm mechanism according to claim 7, wherein the robot arm mechanism is arranged with a space therebetween.   The robot arm mechanism according to claim 9, wherein the plurality of pulleys have a rotation axis substantially parallel to a radial direction centering on an axis of the base.   8. The robot arm mechanism according to claim 7, wherein the path extension portion further includes a biasing mechanism that biases the pulley along the axial direction of the base portion. The base,
An arm having a linear motion joint attached to the base;
A cable for supplying at least one of electric power and a signal to the tip portion of the arm;
A cable guide for guiding the cable from the cable fixing portion on the tip portion side to the base side cable fixing portion;
In order to extend the wiring path by the cable guide from the cable fixing part on the tip part side to the base side cable fixing part, a path extension part interposed on the wiring path,
The path extension includes a plurality of pulleys arranged in a positional relationship for forming a wiring path necessary for reciprocating the cable along the axial direction of the base, and the pulleys in the axial direction of the base. A robot arm mechanism characterized by having an urging mechanism for urging along.