Robot hand

Abstract

To provide a robot hand that can suppress size increases and also suppress interference. [Solution] The hand portion 4, as a robot hand, comprises a palm portion 5 movably supported via a wrist joint 3, a first finger portion 6A movably supported by the palm portion 5, a finger drive mechanism 14 provided on the palm portion 5 as a first drive mechanism for driving the first finger portion 6A, and a flexible shaft 42 as a flexible first power transmission member that passes through the wrist joint 3 and is connected to the finger drive mechanism 14 and transmits driving force for the first finger portion 6A, wherein the flexible shaft 42 passes from the wrist joint 3 through the palm portion 5 and is connected to the finger drive mechanism 14.

Description

Technical Field

[0001] The present invention relates to a robot hand.

Background Art

[0002] In recent years, research and development on robots that contribute to energy efficiency has been carried out to ensure that more people can access affordable, reliable, sustainable and advanced energy.

[0003] As such a robot, there is conventionally known one provided with a driving fluid pressure cylinder for driving an end effector and a driven fluid pressure cylinder (see Patent Document 1). This robot includes a link (arm portion) connected to a base body, and an end effector (hand) connected to the link. The driving fluid pressure cylinder is arranged outside the end effector and supplies working fluid pressure. The driven fluid pressure cylinder is connected to the driving fluid pressure cylinder via a fluid pressure supply pipe, and operates (the corresponding finger mechanism of) the end effector when supplied with the working fluid pressure. In the hand, the fluid pressure supply pipe is connected to the side of the corresponding driven fluid pressure cylinder close to the wrist joint (see FIG. 7 of Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] However, in the conventional technology described above, the fluid pressure supply pipe, which is the power transmission means, is connected to the wrist joint side of the thumb's driven fluid pressure cylinder. As a result, the fluid pressure supply pipe protrudes from the thumb's driven fluid pressure cylinder in the direction of connection, making the hand larger. Furthermore, when the hand rotates (when the wrist joint is driven), the protruding part of the fluid pressure supply pipe interferes with the link (arm), making it impossible to set a large range of motion for the wrist joint.

[0006] In view of the above background, the present invention aims to provide a robot hand that can suppress increasing size and suppress interference. [Means for solving the problem]

[0007] To solve the above problems, one aspect of the present invention provides a robot hand comprising: a palm portion movably supported via a wrist joint; first finger portions movably supported in the palm portion; a first drive mechanism provided in the palm portion for driving the first finger portions; and a flexible first power transmission member connected from the drive source through the wrist joint to the first drive mechanism and transmitting driving force for the first finger portions, wherein the first power transmission member passes from the wrist joint through the palm portion and is connected to the first drive mechanism. [Effects of the Invention]

[0008] In this embodiment, since the first power transmission member passes from the wrist joint through the palm and is connected to the first drive mechanism, the hand size is suppressed. Furthermore, interference between the first power transmission member and the drive source unit during hand rotation (when the wrist joint is driven) is suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] Perspective view of the main part of the end effector. [Figure 2] Longitudinal cross-sectional view of the base end of the shaft unit [Figure 3] Perspective view of the connection structure of the shaft unit [Figure 4] Diagram illustrating the connection structure of the shaft unit. [Figure 5] Operational diagram of the shaft unit connection structure [Figure 6] Operational diagram of the connection structure of the shaft unit according to the comparative example. [Figure 7] A perspective view of the main part of the end effector, seen from a different direction than in Figure 1. [Figure 8] Perspective view of the main part of the end effector in the comparative example, corresponding to Figure 7. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the end effector 1 to which the present invention is applied will be described with reference to the drawings.

[0011] The end effector 1 is a multi-jointed arm equipped with a hand having multiple degrees of freedom, and constitutes the forearm to fingertip portion of the arm of a so-called humanoid robot. Figure 1 shows a perspective view of the end effector 1 according to an embodiment. However, the configuration shown in Figure 1 is merely an example, and the present invention is not limited to this configuration.

[0012] As shown in Figure 1, the end effector 1 comprises a drive source unit 2 corresponding to the forearm and a hand unit 4 connected to the drive source unit 2 via a wrist joint 3. The drive source unit 2 is supported at its proximal end by an elbow joint in the upper arm (not shown). The hand unit 4 is located at the tip of the drive source unit 2 in its extending direction. Hereinafter, the tip of the drive source unit 2 in its extending direction may be referred to as the front, and the proximal end as the rear. The hand unit 4 comprises a palm unit 5 connected to the drive source unit 2 via a wrist joint 3 and a plurality of finger units 6 (6A to 6E) movably supported by the palm unit 5. The palm unit 5 corresponds to the palm of a human hand, and the finger units 6 correspond to human fingers.

[0013] The hand portion 4 of this embodiment is equipped with five finger portions 6: a first finger portion 6A, a second finger portion 6B, a third finger portion 6C, a fourth finger portion 6D, and a fifth finger portion 6E. Hereinafter, when referring to them collectively or without distinction, they may be referred to as finger portions 6. The first finger portion 6A corresponds to the thumb, the second finger portion 6B corresponds to the index finger, the third finger portion 6C corresponds to the middle finger, the fourth finger portion 6D corresponds to the ring finger, and the fifth finger portion 6E corresponds to the little finger.

[0014] The wrist joint 3 has a connecting member 7 that connects the drive source unit 2 and the hand unit 4. The connecting member 7 is connected to the drive source unit 2 so as to be rotatable around a first rotation axis 3X that extends in a direction different from the extension direction of the drive source unit 2 (hereinafter referred to as the X direction), and is connected to the hand unit 4 so as to be rotatable around a second rotation axis 3Y that extends in a direction different from the X direction and the first rotation axis 3X. As a result, the hand unit 4 is rotatable around the first rotation axis 3X and the second rotation axis 3Y. In this embodiment, the first rotation axis 3X is 90 degrees different from the X direction, and the second rotation axis 3Y is 90 degrees different from the first rotation axis 3X. Therefore, the second rotation axis 3Y may be 90 degrees different from the X direction. Also in this embodiment, the first rotation axis 3X and the second rotation axis 3Y intersect each other (i.e., are orthogonal).

[0015] The connecting member 7 is connected to the drive source unit 2 via a rotary first reduction mechanism 8A provided around the first rotation axis 3X. The palm portion 5 is connected to the drive source unit 2 via a rotary second reduction mechanism 8B provided around the second rotation axis 3Y. The first reduction mechanism 8A is a drive mechanism that drives the connecting member 7 relative to the drive source unit 2, and the second reduction mechanism 8B is a drive mechanism that drives the palm portion 5 relative to the connecting member 7. The two reduction mechanisms 8 (8A, 8B) are palm drive mechanisms that rotate the palm portion 5 of the hand portion 4 relative to the drive source unit 2 around the first rotation axis 3X and the second rotation axis 3Y.

[0016] The connecting member 7 is driven by the first palm part drive source 9A via the first speed reduction mechanism 8A. The palm part 5 is driven by the second palm part drive source 9B via the second speed reduction mechanism 8B. The two palm part drive sources 9 (9A, 9B) are drive sources that drive the palm part 5 relative to the drive source unit 2. Each of the palm part drive sources 9 is mounted on the drive source unit 2, and transmits palm part driving force to the rotating shaft portion of the palm part 5 via a palm part driving force transmission mechanism (not shown).

[0017] Each finger part 6 includes a first link 11, a second link 12 and a third link 13 connected in series to the palm part 5, and a finger part drive mechanism 14 that drives the first link 11, the second link 12 and the third link 13. Each finger part drive mechanism 14 is provided on the palm part 5 and the corresponding finger part 6. The finger part drive mechanism 14 that drives the first finger part 6A is provided on the palm side of the palm part 5 and the first finger part 6A. On the other hand, the four finger part drive mechanisms 14 that drive the second finger part 6B, the third finger part 6C, the fourth finger part 6D and the fifth finger part 6E are provided on the back side of the palm part 5 and each finger part 6.

[0018] Each finger part 6 is driven by a plurality of finger part drive sources 15 via the finger part drive mechanism 14. Each finger part drive source 15 is a drive source that drives the corresponding finger part 6 relative to the palm part 5. Each finger part drive source 15 is mounted on the drive source unit 2, and transmits finger part driving force to the corresponding finger part 6 via a finger part driving force transmission mechanism 16 which will be described later. In the present embodiment, 16 finger part drive sources 15 are mounted on the drive source unit 2.

[0019] Further, the drive source unit 2 is provided with a control device 18 that controls the operations of these palm part drive sources 9 and finger part drive sources 15. The control device 18 is arranged at a position aligned with the two palm part drive sources 9 (9A, 9B) in the X direction.

[0020] The drive source unit 2 has a substantially square cross-sectional shape, and includes a drive source casing 20 that defines an accommodation space therein for accommodating the palm part drive sources 9, the finger part drive sources 15 and the control device 18. The palm part drive source 9 is a large-sized electric motor that outputs a relatively large torque, and the finger part drive source 15 is a small-sized electric motor that outputs a relatively small torque.

[0021] The palm drive source 9 comprises a motor body 21 that is cylindrical in shape with a relatively large diameter and is short in the axial direction, an output shaft 22 (see Figure 2) that outputs the driving torque of the motor body 21, and a motor driver 23 that drives the motor body 21. The motor body 21 is mounted in a position with the output shaft 22 facing forward (towards the tip of the drive source unit 2) and is mounted in a relatively rear part of the drive source unit 2, that is, in a part that is far behind the wrist joint 3. The motor driver 23 has a rectangular shape that is close to a square when viewed in the direction of the output axis and is integrally provided at the rear end of the motor body 21.

[0022] The finger drive source 15 comprises a motor body 26 that is cylindrical in shape and has a relatively small diameter, an output shaft 27 that outputs driving torque for the motor body 26, and a motor driver 28 that drives the motor body 26. The motor body 26 is mounted in a position with the output shaft 27 facing forward and is mounted on the front part of the palm drive source 9 in the drive source unit 2. The motor driver 28 has a rectangular shape that is close to a square when viewed from the direction of the output shaft 27 and is integrally provided at the rear end of the motor body 26.

[0023] The output shaft 27 of the finger drive source 15 protrudes slightly from the front of the motor body 26, and its tip (output end) is near the front of the motor body 26 of the finger drive source 15. The output shaft 22 of the palm drive source 9 protrudes significantly from the front of the motor body 21 and is positioned to pass through the gap of the finger drive source 15. The tip (output end) of the output shaft 22 of the palm drive source 9 is in the same position as the output end of the finger drive source 15, that is, near the front of the motor body 26 of the finger drive source 15.

[0024] The 16 finger drive sources 15 are arranged in four rows in the direction of the first rotation axis 3X and in four rows in the direction of the second rotation axis 3Y. These finger drive sources 15 are arranged with gaps in both the direction of the first rotation axis 3X and the direction of the second rotation axis 3Y. Here, "with gaps" means that a gap is formed between the motor drivers 28 with the largest cross-sectional dimensions of two adjacent finger drive sources 15.

[0025] The output shaft 22 of each palm drive source 9 is connected to the corresponding reduction mechanism 8 of the connecting member 7 so as to be able to transmit power by a palm drive force transmission mechanism (not shown). In this embodiment, the palm drive force transmission mechanism is composed of a shaft unit 41 (see Figure 2), which will be described later. Similarly, the output shaft 27 of each finger drive source 15 is connected to the corresponding finger drive mechanism 14 of the palm 5 so as to be able to transmit power by a finger drive force transmission mechanism 16 composed of a shaft unit 41 (see Figure 2).

[0026] Figure 2 is a longitudinal cross-sectional view of the base end of the shaft unit 41. As shown in Figure 2, the shaft unit 41 comprises a flexible shaft 42 and an outer tube 43 that covers the flexible shaft 42. The flexible shaft 42 is flexible and configured to be bendable. The flexible shaft 42 is constructed by arranging several strands of steel wire or the like in strips on a single bendable core wire and winding them in a direction that is a predetermined pitch angle with respect to the axis to form the first winding layer, and then repeating the process of arranging strands in strips and winding them in the opposite direction to form the second, third, and subsequent winding layers.

[0027] The outer tube 43 is cylindrical in shape and has an internal bore through which the flexible shaft 42 is inserted. The outer tube 43 is made of a resin material and is configured to bend and deform like the flexible shaft 42. The flexible shaft 42 is slidably inserted into the internal bore of the outer tube 43. It is preferable that grease be injected into the inside of the outer tube 43 as a lubricant. The outer tube 43 protects the flexible shaft 42 from dust and moisture and prevents the flexible shaft 42 from coming into contact with other components.

[0028] The outer tube 43 is made of a porous material. As a result, the grease contained inside seeps out to the outer surface of the outer tube 43. Therefore, when the outer tube 43 comes into contact with and slides against other external components, it can slide with little resistance.

[0029] Connecting members 47 are attached to the base and end of the flexible shaft 42 for the output shafts 22 and 27 of the corresponding palm drive source 9 or finger drive source 15 and the finger drive mechanism 14. The connecting members 47 constitute a first connecting mechanism 48 for the output shafts 22 and 27 of the corresponding palm drive source 9 or finger drive source 15.

[0030] Specifically, the output ends of the output shafts 22 and 27 of the palm drive source 9 and the finger drive source 15 have plate-shaped (minus screwdriver-shaped) engaging projections 49 that extend radially through the center. The connecting member 47 provided at the base end of the flexible shaft 42 has an engaging groove 50 that can receive the engaging projections 49. These constitute the first connecting mechanism 48.

[0031] By sliding the flexible shaft 42 toward the output shafts 22 and 27 at a rotational angle that matches the engagement groove 50 with the engagement projection 49, the engagement projection 49 is inserted into the engagement groove 50. As a result, the flexible shaft 42 and the corresponding output shafts 22 and 27 are connected to each other via the first connecting mechanism 48 so that power can be transmitted between them.

[0032] If the number of palm drive sources 9 and finger drive sources 15 is large, the number of flexible shafts 42 connected to their output shafts 22 and 27 will also increase, and the assembly time of the end effector 1 will be longer. In this embodiment, since the first connecting mechanism 48 is employed, the flexible shafts 42 can be connected to the corresponding output shafts 22 and 27 of the palm drive source 9 or finger drive source 15 by inserting them. Therefore, the assembly time of the end effector 1 is shortened.

[0033] The connecting member 47 of the flexible shaft 42 is rotatably held via a bearing 51 attached to the drive source casing 20 of the drive source unit 2. The outer tube 43 is held slidably and rotatably in the extending direction by a holding member 52 attached to the drive source casing 20.

[0034] Each finger drive mechanism 14 has a plurality of lead screw mechanisms 55 (see Figure 3) to drive the corresponding finger 6 which has four degrees of freedom. As shown in Figure 3, each lead screw mechanism 55 has a screw shaft 56 to which the end of the flexible shaft 42 is connected, a slider 57 having a female thread that screws onto the male thread of the screw shaft 56, and a rod 58 connected to the slider 57. The flexible shaft 42 is connected to one end of the screw shaft 56 via a plug-in connecting mechanism similar to that in Figure 2. A retaining member 52 (see Figures 2 and 5) is attached to the part of the lead screw mechanism 55 on the side to which the flexible shaft 42 is connected, and the outer tube 43 is held by the retaining member 52 so that it can slide and rotate in the extending direction.

[0035] The torque transmitted from the flexible shaft 42 to the screw shaft 56 of the lead screw mechanism 55 is converted into linear motion of the slider 57 and drives the finger drive mechanism 14 via the rod 58. Each finger drive mechanism 14 is provided with multiple lead screw mechanisms 55. Each lead screw mechanism 55 and its corresponding shaft unit 41 constitute the finger drive force transmission mechanism 16 of each finger drive source 15.

[0036] Furthermore, multiple actuators are composed of multiple finger drive sources 15, multiple shaft units 41, and multiple lead screw mechanisms 55. Each lead screw mechanism 55 constitutes the output section of the corresponding actuator. A certain finger 6 is driven with four degrees of freedom by, for example, four actuators via the finger drive mechanism 14.

[0037] Next, the connection structure of the flexible shafts 42 will be explained with reference to Figures 3 to 6. Figure 3 is a perspective view of the connection structure of the flexible shafts 42. In Figure 3, only the four flexible shafts 42 connected to the four finger drive sources 15 located at the four corners of the rectangular drive source unit 2 are shown, out of the 16 flexible shafts 42, and the other 12 flexible shafts 42 are not shown. The following explanation will use the up / down and left / right directions indicated by the arrows in Figure 3.

[0038] As shown in Figure 3, the finger drive source 15 located in the upper right is connected to the feed screw mechanism 55 in the lower left by a flexible shaft 42 (hereinafter referred to as the first shaft 42A). The finger drive source 15 located in the upper left is connected to the feed screw mechanism 55 in the lower right by another flexible shaft 42 (hereinafter referred to as the second shaft 42B). The finger drive source 15 located in the lower left is connected to the feed screw mechanism 55 in the upper right by another flexible shaft 42 (hereinafter referred to as the third shaft 42C). The finger drive source 15 located in the lower right is connected to the feed screw mechanism 55 in the upper left by another flexible shaft 42 (hereinafter referred to as the fourth shaft 42D). The flexible shafts 42 are connected in this arrangement. That is, the multiple flexible shafts 42 are connected in a twisted positional relationship between the drive source unit 2 and the hand unit 4. Therefore, each flexible shaft 42 is arranged to form an S-shape. Here, the S-shape is a shape in which two C-shapes with different curvature directions are connected to each other. In this specification, the term "S-shape" includes inverted S-shapes.

[0039] Figure 4 is an explanatory diagram of the connection structure of the flexible shafts 42. Figure 4(A) shows the connection structure of the multiple flexible shafts 42 before twisting the connection positions, and Figure 4(B) shows the connection structure of the multiple flexible shafts 42 after twisting the connection positions.

[0040] In Figure 4(A), the first shaft 42A connects the finger drive source 15 located in the upper right to the feed screw mechanism 55 located in the upper right. The second shaft 42B connects the finger drive source 15 located in the upper left to the feed screw mechanism 55 located in the upper left. The third shaft 42C connects the finger drive source 15 located in the lower left to the feed screw mechanism 55 located in the lower left. The fourth shaft 42D connects the finger drive source 15 located in the lower right to the feed screw mechanism 55 located in the lower right.

[0041] In Figure 4(B), the connection structure of the multiple flexible shafts 42 is the same as the connection structure obtained by rotating the hand unit 4 180° relative to the drive source unit 2 from the state in Figure 4(A). Here, the connection structure rotated 180° does not mean the structure obtained by actually rotating the hand unit 4 after connecting the multiple flexible shafts 42, but rather means that it is the same wiring structure as in that case. By having the flexible shafts 42 have such a connection structure, the rotational resistance when the drive source unit 2 and the hand unit 4 rotate around the first rotation axis 3X and the second rotation axis 3Y is reduced. The configuration and effects will be explained below.

[0042] Figure 5 is an explanatory diagram of the operation of the connection structure of the flexible shaft 42, and Figure 6 is an explanatory diagram of the operation of the connection structure of the flexible shaft 42 according to a comparative example. Here, the operation when the hand part 4 rotates around the first rotation axis 3X relative to the drive source part 2 is explained, but the operation when it rotates around the second rotation axis 3Y is similar. In both figures, (A) shows the state in which the hand part 4 is in the neutral position of the rotation range relative to the drive source part 2. (B) shows the state in which the hand part 4 is at the left limit position of the rotation range relative to the drive source part 2. (C) shows the state in which the hand part 4 is at the right limit position of the rotation range relative to the drive source part 2. Note that the hand part 4 is shown with only the palm part 5, omitting the finger parts 6.

[0043] First, with reference to Figure 6, the connection structure of the flexible shaft 42 in the comparative example will be described. The connection position and the rotation direction of the hand portion 4 are based on the left and right directions shown in Figure 3.

[0044] As shown in Figure 6(A), in the comparative example, the flexible shaft 42 connects corresponding positions on the drive source unit 2 and the hand unit 4. Two of the multiple flexible shafts 42 (42A and 42B) will be described below. The first shaft 42A connects the finger drive source 15 located in the upper right to the feed screw mechanism 55 (Figure 3) located in the upper right. The second shaft 42B connects the finger drive source 15 located in the upper left to the feed screw mechanism 55 located in the upper left. When the hand unit 4 is in the neutral position, the two flexible shafts 42 (42A and 42B) have a length that allows them to slacken so that the hand unit 4 can rotate. The middle portion of each flexible shaft 42 passes near the first rotation axis 3X.

[0045] As shown in Figure 65(B), when the hand portion 4 rotates to its leftmost position, the slack in the first shaft 42A decreases. In other words, the first shaft 42A deforms to extend. As a result, the middle portion of the first shaft 42A moves away from the first rotation axis 3X. On the other hand, the slack in the second shaft 42B increases. In other words, the first shaft 42A deforms to curve. As a result, the middle portion of the second shaft 42B moves closer to the first rotation axis 3X, moves beyond the first rotation axis 3X, or twists to form a loop.

[0046] As shown in Figure 6(C), when the hand unit 4 is rotated to the rightmost position, the first shaft 42A and the second shaft 42B move in the opposite direction to when they were rotated to the leftmost position.

[0047] In this way, regardless of whether the hand unit 4 rotates to the left or right, the two flexible shafts 42 (42A, 42B) deform by extending or bending, and their mid-lengths are significantly displaced. As a result, the deformation of the flexible shafts 42 creates rotational resistance for the hand unit 4, and the flexible shafts 42 may come into contact with other flexible shafts 42 or other components such as the connecting member 7, which also creates rotational resistance for the hand unit 4.

[0048] On the other hand, the connection structure of the flexible shaft 42 in this embodiment has low rotational resistance. The connection structure of the flexible shaft 42 according to this embodiment will be described with reference to Figure 5. Here again, two flexible shafts 42 (42A, 42B) will be described.

[0049] As shown in Figure 5(A), the first shaft 42A connects the finger drive source 15 located in the upper right to the feed screw mechanism 55 (Figure 3) located in the lower left. The second shaft 42B connects the finger drive source 15 located in the lower left to the feed screw mechanism 55 in the upper right.

[0050] Therefore, in the axial view of the first rotation axis 3X (Figure 5), both flexible shafts 42 exhibit an S-shape (one is S-shaped, and the other is an inverted S-shape). Here, the axial view of the first rotation axis 3X refers to the viewpoint seen from the axial direction of the first rotation axis 3X, and the axial direction of the first rotation axis 3X is the direction perpendicular to the plane of paper in Figure 5. Specifically, the first shaft 42A has a first portion 42a having curvature in a first direction located on the drive source 2 side, and a second portion 42b having curvature in a second direction opposite to the first direction located on the hand portion 4 side. On the other hand, the second shaft 42B has a first portion 42a having curvature in a first direction located on the hand portion 4 side, and a second portion 42b having curvature in a second direction located on the drive source 2 side.

[0051] In other words, when the hand portion 4 is in the neutral position, the two flexible shafts 42 have a length that allows them to slacken so that the hand portion 4 can rotate. The middle portion of each flexible shaft 42 passes near the first rotation axis 3X. Preferably, the middle portion of each flexible shaft 42 is located on the first rotation axis 3X.

[0052] As shown in Figure 5(B), when the hand portion 4 rotates to the leftmost position, the first shaft 42A deforms such that the length of the first portion 42a decreases and the length of the second portion 42b increases. On the other hand, the second shaft 42B deforms such that the length of the first portion 42a increases and the length of the second portion 42b decreases. Neither the first shaft 42A nor the second shaft 42B deforms in a way that significantly changes their curvature. Therefore, the amount of movement of the intermediate portion of each flexible shaft 42 relative to the first rotation axis 3X is smaller than in the comparative example.

[0053] As shown in Figure 5(C), when the hand unit 4 rotates to the rightmost position, the first shaft 42A and the second shaft 42B move in the opposite direction to when they rotated to the leftmost position. Even in this case, the deformation of each flexible shaft 42 is small, and the amount by which the middle portion of each flexible shaft 42 moves relative to the first rotation axis 3X is small.

[0054] In this way, regardless of whether the hand portion 4 is rotated to the leftmost or rightmost position, the first shaft 42A and the second shaft 42B deform in such a way that their inflection points are displaced, but they do not deform in such a way that their curvature changes significantly or their intermediate portions in the longitudinal direction are significantly displaced. As a result, the deformation of the flexible shaft 42 does not create resistance, and contact between the flexible shaft 42 and other members such as other flexible shafts 42 or connecting members 7 is suppressed, thereby suppressing an increase in the rotational resistance of the hand portion 4.

[0055] In particular, in this embodiment, a flexible shaft 42 is used as a cable to transmit torque. Therefore, if the flexible shaft 42 comes into contact with another component while rotating to transmit torque, the rotation of the flexible shaft 42 is hindered, and the torque transmitted by the flexible shaft 42 fluctuates. In this embodiment, since the flexible shaft 42 is housed in an outer tube 43 into which grease has been injected, the flexible shaft 42 rotates with low resistance inside the outer tube 43, and torque can be transmitted efficiently.

[0056] Here, with reference to Figure 5, the operation and effects of the first rotation axis 3X in an axial view have been explained, but the flexible shaft 42 operates similarly and produces similar effects in an axial view of the second rotation axis 3Y.

[0057] Because the flexible shaft 42 is in a twisted positional relationship with the drive source unit 2 and the hand unit 4, the cable is arranged to exhibit an S-shape in both the axial view of the first rotation axis 3X and the axial view of the second rotation axis 3Y. Therefore, cable wiring is easy.

[0058] The above describes the connection structure of the flexible shaft 42 from the second finger portion 6B to the fourth finger portion 6D. Next, the connection structure of the flexible shaft 42 to the first finger portion 6A will be described.

[0059] First, the structure of the first finger portion 6A will be described with reference to Figure 3. Below, the state in which the hand portion 4 is in the neutral position will be described. As shown in Figure 3, the first finger portion 6A is attached to the palm portion 5 in a different manner from the other finger portions 6 (6B, 6C, 6D). Specifically, the second finger portions 6B to the fourth finger portions 6D extend in the X direction from the tip of the palm portion 5 (the tip in the X direction). Therefore, the finger drive mechanism 14 that drives them is arranged parallel to each other in the X direction on the tip side of the palm portion 5.

[0060] On the other hand, the first finger portion 6A extends upward from the midpoint and rightmost position in the X direction of the palm portion 5. Therefore, its finger drive mechanism 14 is located at the midpoint and rightmost position in the X direction of the palm portion 5.

[0061] Next, the connection structure of the flexible shaft 42 to the first finger portion 6A will be described with reference to Figures 7 and 8. Figure 7 is a perspective view of the main part of the end effector 1 from a different direction than that of Figure 1. Figure 8 is a perspective view of the main part of the end effector 1 according to a comparative example, corresponding to Figure 7.

[0062] First, with reference to Figure 8, the connection structure of the flexible shaft 42 in the comparative example will be described. In this comparative example, multiple flexible shafts 42 are connected to the drive source 2 side opposite to the X direction of the finger drive mechanism 14 of the first finger 6A.

[0063] Therefore, when the hand portion 4 rotates upward (towards the first finger portion 6A) around the second rotation axis 3Y, the flexible shaft 42 deforms significantly into a Z-shape, and the curvature of the maximum curvature increases. Consequently, the deformation of the flexible shaft 42 creates resistance, and the power transmission efficiency of the flexible shaft 42 decreases. Furthermore, in order for the hand portion 4 to rotate around the second rotation axis 3Y, the length of the flexible shaft 42 must be set to be long enough to have a large amount of play when the hand portion 4 is in the neutral position. This is also true when the hand portion 4 rotates to the left (towards the first finger portion 6A) around the first rotation axis 3X.

[0064] In contrast, in this embodiment, as shown in Figure 7, a plurality of flexible shafts 42 are connected to the finger drive mechanism 14 of the first finger portion 6A from the X direction. Specifically, the flexible shafts 42 are routed to pass inside the connecting member 7 of the wrist joint 3 and to pass on the back of the palm portion 5. More specifically, the flexible shafts 42 are routed to pass between two adjacent finger drive mechanisms 14 that drive the second finger portion 6B and the third finger portion 6C. This routing structure prevents the flexible shafts 42 from protruding outward from the second finger portion 6B and the third finger portion 6C as they pass through the palm portion 5.

[0065] The flexible shaft 42 then makes a U-turn, wrapping around the tip of the palm portion 5 in the X direction, and is connected to the X-direction end of the finger drive mechanism 14, which is provided on the palm side of the palm portion 5. In other words, the flexible shaft 42 is connected to the end of the finger drive mechanism 14 on the side opposite to the wrist joint 3.

[0066] Therefore, when the hand portion 4 rotates toward the first finger portion 6A around the second rotation axis 3Y or the first rotation axis 3X, the flexible shaft 42 deforms slightly in the U-shaped straight section, curving by an angle corresponding to the rotation angle. The part of the flexible shaft 42 with the greatest curvature is the U-shaped turn, and the curvature of this part does not change. Consequently, a decrease in the power transmission efficiency of the flexible shaft 42 is suppressed. Also, since the flexible shaft 42 passes through the wrist joint 3, the required length of the flexible shaft 42 does not change even when the hand portion 4 rotates around the second rotation axis 3Y or the first rotation axis 3X. There is no need to set a large amount of play in the length of the flexible shaft 42.

[0067] Thus, the flexible shaft 42 passes through the back of the palm portion 5 and is arranged to curve in a U-shape between the connection point with the finger drive mechanism 14 on the palm side and the portion on the back of the hand that passes through the palm portion 5. Therefore, the length of the flexible shaft 42 extending to the palm side of the palm portion 5 is shortened, and the flexible shaft 42 is prevented from obstructing the movement of the hand portion 4.

[0068] This concludes the description of the embodiments, but the present invention is not limited to the above configuration and can be broadly modified and implemented.

[0069] For example, the end effector 1 of this embodiment has five finger parts 6, but it may have four or fewer, or six or more finger parts 6. Also, the end effector 1 has 16 finger drive sources 15, but the number of finger drive sources 15 is not limited to this. The end effector 1 is applied to the arm of a humanoid robot, but it may be applied to parts other than the arm of a humanoid robot, or to robots other than humanoid robots.

[0070] Furthermore, the flexible shaft 42 does not necessarily have to be inserted into the outer tube 43; it may be inserted into an outer member other than the outer tube 43. The outer member can be any flexible tube, and may be a protective member formed by spirally shaping tape, a mesh sheet, or a tube made of a porous sheet. By being inserted into the outer member, the flexible shaft 42 is protected and interference with the outside is suppressed, allowing for efficient torque transmission.

[0071] In addition, the specific configuration, arrangement, and quantity of each component and part can be modified as appropriate, as long as it does not depart from the spirit of the present invention. Furthermore, some or all of the components of the above embodiments may be combined with each other. On the other hand, not all of the components shown in the above embodiments are necessarily essential, and can be selected as appropriate.

[0072] In conclusion, the above embodiments can be summarized as follows:

[0073] One embodiment is a mechanical device exemplified by an end effector 1, comprising: a first member exemplified by a drive source 2; a second member exemplified by a hand portion 4 connected to the first member via a joint (wrist joint 3) rotatable around a first rotation axis 3X; and at least one flexible cable supported by the first member and the second member and exemplified by a flexible shaft 42, wherein the cable exhibits an S-shape between the first member and the second member in an axial view of the first rotation axis 3X when the first member and the second member are in a neutral position within their rotational range around the first rotation axis 3X.

[0074] According to this embodiment, when the first member and the second member rotate relative to each other around the first rotation axis 3X, the cable deforms in such a way that it displaces its inflection point, but does not deform in such a way that it significantly changes its curvature or significantly displaces its mid-length portion. Therefore, the deformation of the cable does not create resistance to the rotational movement, nor does the cable come into contact with surrounding members and create resistance to the rotational movement. Consequently, the energy efficiency of the mechanical device is improved.

[0075] In the above embodiment, preferably, the cable has a first portion 42a having curvature in a first direction and a second portion 42b having curvature in a second direction opposite to the first direction when the first member and the second member are in a neutral position within the rotational range of the first rotation axis 3X.

[0076] According to this embodiment, when the first member and the second member rotate relative to each other around the first rotation axis 3X, the length of one of the first and second members of the cable increases while the length of the other decreases, while the cable does not change its curvature or undergo significant displacement in the middle section in the longitudinal direction. Therefore, contact between the cable and surrounding members is suppressed.

[0077] In the above embodiment, preferably, the connection between the first portion 42a and the second portion 42b is located on the first rotation axis 3X.

[0078] In this embodiment, when the first member and the second member rotate relative to each other around the first rotation axis 3X, the displacement of the cable relative to the first rotation axis 3X is minimized. Therefore, rotational resistance due to cable contact is effectively suppressed.

[0079] In the above embodiment, preferably, the cable has a first portion 42a having curvature in a first direction and a second portion 42b having curvature in a second direction opposite to the first direction, and the cable includes a flexible shaft 42 as a first cable having the first portion 42a on the first member side and the second portion 42b on the second member side, and a flexible shaft 42 as a second cable having the first portion 42a on the second member side and the second portion 42b on the first member side.

[0080] When two cables are arranged side by side, there is a risk that a difference in rotational resistance may occur depending on the direction in which the first and second members rotate relative to each other. In this embodiment, the first cable and the second cable are arranged to intersect in an axial view of the first rotation axis 3X. Therefore, the difference in rotational resistance caused by the direction in which the first and second members rotate relative to each other is suppressed.

[0081] In the above embodiment, preferably, the wrist joint 3 is configured to be rotatable about a second rotation axis 3Y that extends in a direction different from the extending direction of the first rotation axis 3X, and the cable exhibits an S-shape between the first member and the second member when the first member and the second member are in a neutral position within the rotation range around the second rotation axis 3Y, in an axial view of the second rotation axis 3Y.

[0082] In this embodiment, even when the first member and the second member rotate relative to each other around the second rotation axis 3Y, the cable changes its inflection point but does not undergo significant displacement. Therefore, contact between the cable and surrounding members, which would create resistance to rotation, is suppressed.

[0083] In the above embodiment, preferably, the plurality of cables are in a twisted positional relationship between the first member and the second member.

[0084] In this embodiment, the cable is arranged to exhibit an S-shape in both the axial view of the first rotation axis 3X and the axial view of the second rotation axis 3Y. Therefore, cable wiring is facilitated.

[0085] In the above embodiment, preferably, the cable is a power transmission cable and is covered by an outer member exemplified by the outer tube 43.

[0086] When many cables are arranged, they may come into contact with each other when the first and second members rotate relative to each other. If the cables are power transmission cables, contact between cables will affect the power transmitted. In this embodiment, the cables will not come into contact with each other when the first and second members rotate relative to each other. Therefore, the driving force transmitted by the cables will not be affected by contact between cables.

[0087] In the above embodiment, preferably, the power transmission cable is a flexible shaft 42 that transmits torque, and the outer member is an outer tube 43 that houses the flexible shaft 42 and a lubricant.

[0088] According to this embodiment, the flexible shaft 42 rotates with low resistance inside the outer tube 43, allowing for efficient transmission of torque.

[0089] In the above embodiment, preferably, the outer tube 43 is made of a porous material.

[0090] In this embodiment, the lubricant inside the outer tube 43 seeps out onto the outer surface of the outer tube 43. Therefore, when the outer tube 43 comes into contact with and slides against other external components, it can slide with minimal resistance.

[0091] In the above embodiment, preferably, the outer member is supported so as to be slidable in the extending direction on at least one of the first member and the second member.

[0092] According to this embodiment, when the length of the power transmission cable and the outer member changes due to the difference in thermal expansion coefficients, the S-shaped arrangement of the power transmission cable is prevented from coming into contact with the inner surface of the outer member. This prevents an increase in the operating resistance of the power transmission cable during thermal expansion.

[0093] In the above embodiment, preferably, the first member is a drive source unit 2, and the second member is a hand unit 4 comprising a palm unit 5 supported by the drive source unit 2 via the joints and finger units 6 movably supported by the palm unit 5, and the mechanical device constitutes the end effector 1.

[0094] According to this embodiment, an end effector 1 can be provided in which the cable is wired in such a way that it does not interfere with the rotational movement between the drive source unit 2 and the hand unit 4.

[0095] Furthermore, the above embodiment can also be described as follows.

[0096] One embodiment is a robot hand comprising a hand portion 4 of an end effector 1, comprising a palm portion 5 movably supported via a wrist joint 3, first finger portions 6A movably supported on the palm portion 5, a finger drive mechanism 14 provided on the palm portion 5 as a first drive mechanism for driving the first finger portions, and a flexible shaft 42 as a flexible first power transmission member that is connected to the first drive mechanism from the drive source 2 through the wrist joint 3 and transmits driving force for the first finger portions 6A, wherein the first power transmission member passes from the wrist joint 3 through the palm portion 5 and is connected to the first drive mechanism.

[0097] In this embodiment, since the first power transmission member passes from the wrist joint 3 through the palm portion 5 and is connected to the first drive mechanism, the size of the hand portion 4 is suppressed. In addition, interference between the first power transmission member and the drive source portion 2 when the hand portion 4 rotates (when the wrist joint 3 is driven) is suppressed.

[0098] In the above embodiment, preferably, the first power transmission member is connected to the side of the first drive mechanism opposite to the wrist joint 3.

[0099] According to this embodiment, even if the first power transmission member extends from the first drive mechanism of the first finger portion 6A in the direction of connection, the hand portion 4 is prevented from becoming larger.

[0100] In the above embodiment, preferably, the palm 5 further comprises a plurality of second finger portions 6B and third finger portions 6C supported on the side of the palm 5 opposite to the wrist joint 3, two finger drive mechanisms 14 provided on the palm 5 as a plurality of second drive mechanisms for driving the second finger portions 6B and third finger portions 6C, and two flexible shafts 42 as a plurality of flexible second power transmission members that are connected to the second drive mechanisms from the drive source 2 through the wrist joint 3 and transmit driving force for the second finger portions 6B and third finger portions 6C, wherein the first power transmission member passes between a pair of adjacent second drive mechanisms in the palm 5.

[0101] According to this embodiment, the first power transmission member is prevented from protruding outward from the second drive mechanism as it passes through the palm portion 5. This prevents the robot hand from becoming larger.

[0102] In the above embodiment, preferably, the first drive mechanism and the plurality of second drive mechanisms are arranged on opposite sides of the palm portion 5, and the first power transmission member is curved in a U-shape so as to wrap around the tip of the palm portion 5 between the connection portion with the first drive mechanism and the portion between the second drive mechanisms.

[0103] According to this embodiment, the length of the first power transmission member extending to the side of the palm portion 5 where the first drive mechanism is located is shortened, and the first power transmission member is less likely to interfere with the movement of the robot hand.

[0104] In the above embodiment, preferably, the first power transmission member is a flexible shaft 42 that transmits torque and is inserted into an outer member exemplified by an outer tube 43.

[0105] In this embodiment, since the flexible shaft 42 is protected by the outer member, torque is efficiently transmitted to the first drive mechanism.

[0106] In the above embodiment, preferably, the outer member is an outer tube 43 that houses the flexible shaft and the lubricant.

[0107] According to this embodiment, the flexible shaft 42 can transmit torque to the first drive mechanism more efficiently.

[0108] In the above embodiment, preferably, the first drive mechanism comprises a screw shaft 56, a slider 57 that screws onto the screw shaft 56, and a rod 58 driven by the slider 57, wherein the first power transmission member is connected to the side of the screw shaft 56 opposite to the wrist joint 3.

[0109] In this embodiment, the torque transmitted to the first drive mechanism is converted into linear motion of the slider 57, which drives the first finger portion 6A via the rod 58. [Explanation of Symbols]

[0110] 1: End effector (an example of a mechanical device) 2: Drive source unit (an example of the first component) 3: Wrist joint 3X: First axis of rotation 3Y: Second rotation axis 4: Hand section (an example of a second component, an example of a robot hand) 5: Palm 6: Finger part 6A: 1st finger part (1st finger part) 6B: 2nd finger part (2nd finger part) 6C: 3rd finger (2nd finger) 6D: 4th finger (2nd finger) 7: Connecting member 14: Finger drive mechanism 41: Shaft Unit 42: Flexible shaft (an example of a cable, an example of a power transmission member) 42A: First cable 42B: Second cable 42a: Part 1 42b :Second part 43: Outer tube (an example of an outer component) 55: Lead screw mechanism 56: Screw shaft 57: Slider 58: Rod

Claims

1. It is a robotic hand, The palm, which is supported movably via the wrist joint, The first finger portion is movably supported in the palm, A first drive mechanism provided in the palm portion for driving the first finger portion, The system includes a first power transmission member that passes through the wrist joint and is connected to the first drive mechanism, and is flexible in transmitting driving force for the first finger portion, A robot hand in which the first power transmission member passes from the wrist joint through the palm and is connected to the first drive mechanism.

2. The robot hand according to claim 1, wherein the first power transmission member is connected to the side of the first drive mechanism opposite to the wrist joint.

3. Multiple second finger portions supported on the side of the palm opposite to the wrist joint, A plurality of second drive mechanisms are provided on the palm portion for driving the second finger portion, The system further comprises a plurality of flexible second power transmission members that pass through the wrist joint and are connected to the second drive mechanism, and transmit driving force for the second finger portion, The robot hand according to claim 2, wherein the first power transmission member passes between a pair of adjacent second drive mechanisms in the palm portion.

4. The first drive mechanism and a plurality of the second drive mechanisms are arranged on opposite sides of the palm portion. The robot hand according to claim 3, wherein the first power transmission member is curved in a U-shape so as to wrap around the tip of the palm portion between the connection portion with the first drive mechanism and the portion between the connection portion with the second drive mechanism.

5. The robot hand according to any one of claims 1 to 4, wherein the first power transmission member is a flexible shaft for transmitting torque and is inserted into the outer member.

6. The robot hand according to claim 5, wherein the outer member is an outer tube that houses the flexible shaft and the lubricant.

7. The first drive mechanism comprises a screw shaft, a slider that is screwed onto the screw shaft, and a rod that is driven by the slider. The robot hand according to claim 5, wherein the first power transmission member is connected to the side of the screw shaft opposite to the wrist joint.

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