Robot joint structure

Abstract

The present invention provides an MP joint mechanism with a wiring structure in which the DIP joint drive wire and PIP joint drive wire do not affect the adduction / abduction movement of the MP joint, while providing passive torque to amplify the flexion movement of the MP joint. [Solution] The present invention provides a mechanism in which a central component (description omitted) rotatably holds the first, second, and third DIP pulleys (9, 10, 11) and the first, second, and third PIP pulleys (12, 13, 14), and includes a DIP wire (4), the DIP wire (4) being wrapped once around the first DIP pulley (9), guided by the second DIP pulley (10), and then guided by the third DIP pulley.

Description

Technical Field

[0006] , , , ,

[0001] Relates to the joint structure of a robot, particularly to the structure of a joint driven by a wire.

Background Art

[0002] When the structure and movement of a human finger are grasped engineeringly, it can be regarded as a wire-driven 4-degree-of-freedom manipulator. The joints of the finger have anatomical names and are called the DIP joint, PIP joint, and MP joint from the fingertip. The DIP joint and PIP joint can be regarded as 1-degree-of-freedom hinges, and the MP joint can be regarded as a 2-degree-of-freedom universal joint.

[0003] For the MP joint, it is necessary to pass two wires that drive the DIP joint and PIP joint respectively. When the MP joint makes a left-right swinging motion (abduction / adduction motion), it is desirable to keep the wires from contacting each other. Furthermore, when tension is applied to the wires, it is necessary to wire the wires so that no extra passive torque is generated to abduct / adduct the MP joint. On the other hand, it is desirable to wire the wires so that passive torque contributes to the bending motion (flexion motion) of the MP joint, and the processing of wire wiring in the MP joint is not easy.

[0004] In fact, looking at a known invention (for example, Document 1), the abduction / adduction axis and flexion / extension axis of the MP joint are not offset and are in a twisted position, and the passive torque is not effectively utilized, indicating that the processing of wire wiring in the MP joint is difficult.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the present invention provides an MP joint mechanism with a wiring structure in which the DIP joint drive wire and PIP joint drive wire do not apply passive torque to the adduction / abduction movement of the MP joint, but apply passive torque to the flexion movement of the MP joint to increase force. [Means for solving the problem]

[0007] First, we will explain the important mechanical properties related to the present invention. Figure 1 shows a mechanical model of a human finger, which comprises a distal phalangeal frame (101), a middle phalangeal frame (102), a proximal phalangeal frame (103), a base (104), a DIP pulley (105), a PIP pulley (106), and an MP pulley (107). The joint connecting the distal phalangeal frame (101) and the middle phalangeal frame (102) is called a DIP (Distal Inter Phalangeal) joint, the joint connecting the middle phalangeal frame (102) and the proximal phalangeal frame (103) is called a PIP (Proximal Inter Phalangeal) joint, and the joint connecting the proximal phalangeal frame (103) and the base (104) is called an MP (Metacarpo Phalangeal) joint. The DIP pulley (105), PIP pulley (106), and MP pulley (107) are rotatably held coaxially with the DIP, PIP, and MP joints, respectively. The movement of each joint is called flexion when rotating in the direction of bending the finger, and extension when rotating in the opposite direction. The movement of the MP joint from side to side is called adduction and abduction, and in this invention, the movement in the clockwise direction when viewed from the direction of the back of the finger is called adduction, and the opposite direction is called abduction. The operation of this model is described below.

[0008] Figure 2 shows the wiring of a DIP wire (108) for driving the DIP joint or distal phalangeal frame (101). The wiring is characterized by wrapping once around the MP pulley (107), once around the PIP pulley (106), once around the DIP pulley (105), and then from the direction of the base (104) through the palm side of the finger, before being fixed to the distal phalangeal frame (101). Although not shown, the DIP joint and PIP joint are provided with restoring force by torsion springs or the like.

[0009] In this mechanism, when tension is applied to the DIP wire (108) using the base (104) as a mechanical reference, driving torque is generated in the MP joint, PIP joint, and DIP joint according to their respective pulley radii and wire tension. However, since it is a mechanically inferior drive system, its operation is unpredictable.

[0010] As one example of several operating modes, when the middle section frame (102) and the proximal section frame (103) are fixed to the base (104), when tension is applied to the DIP wire (108), only the DIP joint or the distal section frame (101) bends, and when the tension is released, the DIP joint extends due to the restorative force of the DIP joint.

[0011] As a second example, if only the base frame (103) is fixed to the base (104), the PIP joint flexes first, and when it reaches its rotational limit, the DIP joint flexes, resulting in a so-called winding motion. If the terminal frame (101) comes into contact with the object before the PIP joint reaches its rotational limit, it stops in that position, but if the tension is further increased, the DIP and PIP joints will attempt to rotate, resulting in a scratching motion against the surface of the object.

[0012] As a third example, if the distal phalangeal frame (101), middle phalangeal frame (102), and proximal phalangeal frame (103) are all free, the MP joint flexes first, and when it reaches its rotational limit, the PIP joint flexes, and when it also reaches its rotational limit, the DIP joint flexes last. While the MP joint is flexing, the PIP and DIP joints flex gradually according to the degree of restoring force, so rather than the joints bending sequentially, the movement is more like the fingers bending smoothly as a whole. If the proximal phalangeal frame (103) comes into contact with an object during the overall flexion, the distal phalangeal frame (101) and middle phalangeal frame (102), or the DIP joint and PIP joint, continue their curling motion. If the middle phalangeal frame (102) comes into contact with an object during the overall flexion, the distal phalangeal frame, or the DIP joint, continues its flexion. If the distal segment frame (101) comes into contact with an object during the overall bending, it will stop in that position. However, if the tension is further increased, the DIP and PIP joints will attempt to rotate, resulting in a scratching motion on the surface of the object.

[0013] Mechanisms with such indeterminate properties are called sub-acting systems, and are often treated as advantages rather than disadvantages because they enable a so-called winding motion, which helps the fingers to follow the object and firmly grasp it. In order to achieve this characteristic, the torque (called passive torque) that is incidentally generated in the PIP and MP joints when the DIP joint is driven plays an important role, so it is extremely important to wire the DIP wire (108) in a way that does not impair this passive torque.

[0014] Figure 3 shows the wiring of a PIP wire (109) for driving a PIP joint or middle section frame (102). The wiring is characterized by wrapping once around the MP pulley (107) from the direction of the base (104), wrapping once around the PIP pulley (106), and fixing the end to the middle section frame (102). Although not shown in the figure, in this figure as well, the DIP joint and PIP joint are assumed to have a restoring force such as a torsion spring.

[0015] In this configuration as well, if the DIP joint or distal frame (101) is ignored, the same effect as that provided by the DIP wire (108) can be obtained. However, the DIP wire (108) and the PIP wire (109) must not come into contact with each other, for example, by using separate pulleys, so as not to interfere with each other's movement. Also, as with the DIP wire (108), it is extremely important that the PIP wire (109) is wired in a way that does not impair its passive torque.

[0016] A notable effect here is that the passive torques of the DIP wire (108) and PIP wire (109) are added together without mechanical interference. That is, while only the tension of the DIP wire (108) contributes to the DIP joint, the PIP joint benefits from both the direct torque provided by the tension of the PIP wire (109) and the passive torque provided by the tension of the DIP wire (108), and the MP joint benefits from the passive torques of both the DIP wire (108) and the DIP wire (109), resulting in a force amplification effect.

[0017] Direct drive of MP joints does not require sub-drive and does not involve particularly complex movements.

[0018] Now, I have omitted the explanation of the adduction and abduction movements of the MP joint, but when implementing this, it is difficult to wire the DIP wire and PIP wire so as not to come into contact with each other, while also generating an appropriate passive torque in the flexion direction of the MP joint. The following describes the means to solve this problem.

[0019] Figure 4 shows a part of the MP joint structure that enables this wiring, where the direction of the inversion / abversion axis coincides with the Z axis, and the direction of the flexion / extension axis coincides with the Y axis. The positive direction of the X axis indicates the direction of the fingertip. The base middle section (not shown) rotatably holds the first, second, and third DIP pulleys (9, 10, 11) and the first, second, and third PIP pulleys (12, 13, 14), and the DIP wire (4) is characterized by wrapping once around the first DIP pulley (9), being guided by the second DIP pulley (10), and then being guided by the third DIP pulley.

[0020] The positional relationship between the DIP pulleys (9, 10, 11) and PIP pulleys (12, 13, 14), as well as the DIP wire (4) and PIP wire (not shown), is symmetrical with respect to the XZ plane. The rotation axis of the first DIP pulley (9) coincides with the Z axis, and the rotation axis of the third DIP pulley (11) coincides with the Y axis. The rotation axis of the second DIP pulley (10) has a complex inclination angle, and the inclination angle is carefully determined according to the positional relationship between the DIP pulleys (9, 11) so that the DIP wire (4) does not come into contact with the end face of the middle link described later, and so that the wire is smoothly relayed.

[0021] When the DIP wire (4) is pulled in the negative direction of the X-axis, the first DIP pulley (9) rotates counterclockwise around the Z-axis, the second DIP pulley (10) rotates counterclockwise when its axis of rotation is aligned with the Z-axis, and the third DIP pulley (11) rotates clockwise around the Y-axis. Normally, the DIP wire (4) is designed to have a restoring force, so when the pulling force is released, it moves in the opposite direction.

[0022] As shown in the top view of FIG. 5, since the DIP wire (4) is wound around the first DIP pulley (9) once, even if, for example, the MP joint abducts and the position of the DIP pulley (9) changes to (9a), the position of the DIP wire after abduction (4a) hardly changes, and its position is also very close to the neutral plane (XZ plane) including the abduction / adduction axis. Therefore, the passive torque in the abduction / adduction axis direction exerted by the tension of the DIP wire (4) on the MP joint is extremely small, and unnecessary mechanical interference can be avoided. Note that when the range of abduction / adduction of the MP joint is small, or depending on the positional relationship of the pulleys, it may not be necessary to wind the wire.

[0023] On the other hand, looking at the DIP wire (4) extending in the positive X-axis direction (finger tip direction) from the third DIP pulley (11) shown in FIG. 4, its position is away from the flexion / extension axis, and it can be seen that it gives a passive torque in the flexion direction equal to the product of its radius and tension. The PIP wire has the same positional relationship as the DIP wire and brings exactly the same effect. Therefore, by using this mechanism, it is possible to drive the DIP joint and the PIP joint without interfering with or being interfered with by the direct drive of the MP joint, while applying the necessary passive torque.

[0024] FIG. 6 shows a push-pull drive system that directly drives the MP joint around the flexion / extension axis, including the first and second MP forward rotation pulleys (15, 16), the first and second MP reverse rotation pulleys (17, 18), an MP double pulley (19) including a connecting shaft (19a) and a wire intermediate fixing mechanism (19b), and an MP flexion / extension wire (8). The MP flexion / extension wire (8) is wound around the first MP forward rotation pulley (15) once, guided by the second MP forward rotation pulley (16), guided by the forward rotation side pulley (19c) of the MP double pulley, fixes the intermediate part (8c) of the wire, and at the same time passes to the reverse rotation side pulley (19d) of the MP double pulley, is guided by the reverse rotation side pulley (19d), guided by the second MP reverse rotation pulley (18), and wound around the first MP reverse rotation pulley (17) once.

[0025] The first and second MP forward pulleys (15, 16) and the first and second MP reverse pulleys (17, 18) are symmetrically located with respect to the XZ plane. The direction of the rotation axes of the first MP forward pulley (15) and the first MP reverse pulley (17) is equal to the Z axis, and the direction of the rotation axes of the second MP forward pulley (16) and the second MP reverse pulley (18) is equal to the Y axis.

[0026] When the forward side (8a) of the MP flexure wire is pulled in the negative X-axis direction, the first MP forward pulley (15) rotates in the clockwise direction about the Z axis, the second MP forward pulley (16) rotates in the clockwise direction about the Y axis, the MP double pulley (19) rotates in the clockwise direction (forward direction) about the Y axis, the second MP reverse pulley (18) rotates in the counterclockwise direction about the Y axis, the first MP reverse pulley (17) rotates in the counterclockwise direction about the Z axis, and the reverse side (8b) of the MP flexure wire is pulled in the positive X-axis direction.

[0027] The mechanisms shown in FIGS. 4 and 6 can be combined compactly as shown in FIG. 7. The third DIP pulley (11) and the third PIP pulley (14) are combined so as to be rotatable with respect to the connecting shaft (19a) of the MP double pulley (19).

Advantages of the Invention

[0028] When directly driving the flexion / extension axis and the adduction axis of the MP joint respectively, it is possible to drive the DIP joint and the PIP joint by wire without interference or being interfered with, while providing the necessary passive torque.

[0029] In the flexion / extension direction of the MP joint, the DIP wire and the passive torque of the DIP wire contribute, and the tension of the wire or the output of the actuator can be effectively and efficiently utilized.

[0030] The wiring of the wire and the arrangement of the pulleys are effective, and the mechanism is compact.

Brief Description of the Drawings

[0031] [Figure 1] It is a diagram showing a mechanical model of a human finger. [Figure 2] This is a diagram showing the wiring of DIP wires. [Figure 3] This is a diagram showing the wiring of PIP wires. [Figure 4] This diagram shows non-interference wiring of DIP wires. [Figure 5] This is a top view of non-interfering DIP wire wiring. [Figure 6] This diagram shows the non-interfering wiring of MP bending wires. [Figure 7] A diagram showing the combination of non-interfering wiring. [Figure 8] This figure illustrates an embodiment of the present invention. [Figure 9] This is an exploded view of the fixed frame. [Figure 10] This is a front view of the fixed frame. [Figure 11] This is a diagram showing the components of the inner sesame seed. [Figure 12] This diagram shows the side hole of the center piece. [Figure 13] This diagram shows the hollow structure of the center sesame seed. [Figure 14] This diagram shows the gap in a double pulley. [Figure 15] This is a cross-section of a sesame seed. [Figure 16] This is an example of a segment pulley. [Figure 17] This is an exploded view of the base frame. [Figure 18] This diagram shows the wire window of the base frame. [Modes for carrying out the invention]

[0032] Figure 8 shows an embodiment of the present invention, illustrating a mechanism comprising a fixed frame (1), a middle sprocket (2), and a base frame (3).

[0033] Figure 9 shows a detailed exploded view of the fixed frame (1), which is divided into a lower part (1t) and an upper part (1s), each equipped with bearings (201a, 201b) and housings (202a, 202b), respectively. The lower part (1t) of the fixed frame includes an MP internal pulley (1h), an internal pulley shaft (204) that rotatably holds it, an MP external pulley (1j), an external pulley shaft (203) that rotatably holds it, wire guides (205, 206), a nut side hole and a nut (207), and Figure 10 shows a fixed frame (1) characterized by having an MP forward rotation wire hole (1d), an MP reverse rotation wire hole (1e), and a rectangular MP abducting wire hole (1g) as shown in the front view of Figure 10, and the upper part (1s) of the fixed frame having a screw hole (208), a screw (209), a DIP wire hole (1b), a PIP wire hole (1c), and a rectangular MP inward rotation wire hole (1f) as shown in the front view of Figure 10, and fastening the lower part (1t) of the fixed frame to the upper part (1s) of the fixed frame with a nut (207) and a screw (209).

[0034] The DIP wire (4) and PIP wire (5), whose markings are omitted, pass through the DIP wire hole (1b) and PIP wire hole (1c) of the fixed frame (1), respectively, and are guided by the pulleys of the middle section. The MP adduction wire (6), whose markings are omitted, passes through the wire guide (206), is guided by the MP adduction pulley (1h), passes through the MP adduction wire hole (1f), and drives the segment pulley described later. Similarly, the MP abduction wire (7), whose markings are omitted, passes through the wire guide (205), is guided by the MP abduction pulley (1j), passes through the MP abduction wire hole (1g), and drives the segment pulley described later. The MP flexion / extension wire (8), whose markings are omitted, passes through the MP forward rotation wire hole (1d), is guided by the pulleys of the middle section, drives the double pulley, and returns by passing through the MP reverse rotation wire hole (1e).

[0035] Figure 11 shows a detailed exploded view of the center spinner (2), including the upper (2s) and lower (2t) parts of the center spinner, which are divided in half. The upper and lower parts (2s, 2t) of the center spinner are held in place by bearing mounts (214) that sandwich bearings (211, 212), and the bearings (211, 212) engage with the drive shaft of the double pulley (19), thereby holding the double pulley (19) rotatably. Furthermore, by inserting appropriate shim rings or the like between the drive shaft of the double pulley (19) and fitting bearings (210, 213), the PIP pulley (14) and DIP pulley (11) into which they are press-fitted are also held rotatably. The pulleys (9, 10, 17) are inserted laterally through the lateral holes (215, 216, 217) shown in Figure 12, and the drive shafts are appropriately press-fitted to hold them rotatably in the center sprocket (2). The pulleys (12, 13, 15) are held similarly, maintaining a symmetrical positional relationship. Figure 12 also shows the first slot (2b) through which the DIP wire (4) and PIP wire (5) pass, and the second slot (2c) through which both the pushing and pulling of the MP bending wire (8) passes. The lateral holes and slots may be appropriately connected to form a hollow structure according to design and manufacturing considerations. Figure 13 shows an example of a hollow structure in which the center sprocket is cut out from a horizontal plane including the first slot (2b).

[0036] The second MP forward-rotating pulley (16) and the second MP reverse-rotating pulley (18) can be easily inserted through the double pulley gap (215) shown in the cross-sectional view of Figure 14, and the drive shaft (216) is laterally pressed in to hold it rotatably.

[0037] Figure 15 shows a ZY cross-section of the center spinning top, where it can be seen that the second DIP pulley (10) protrudes from the side end face (2e) of the center spinning top and is guided into the groove (11a) of the third DIP pulley without contacting the side end face (2e). The same applies to the second PIP pulley (13), the side end face (2d), and the third PIP pulley (14).

[0038] Figure 16 shows an example of a segment pulley at the bottom (2t) of the center spindle, illustrating the MP outward-rotating segment pulley (2g) cut into the bottom (2t) of the center spindle, the post (2gb) for fixing the wire end, and the wire guide path (217). The post (2gb) is already shown in the cross-sectional view of Figure 14, and the wire is fixed by passing the wire through the hole (218) and securing the end to the hole by tying a knot. In this case, the presence of an access hole (219) improves workability.

[0039] The MP abduction wire, whose designation is omitted, has its end fixed to the post (2gb), passes through the path (217), is guided to the segment pulley (2g), passes through the MP abduction wire hole (1g) described in Figure 10, is guided to the MP abduction pulley (1j), and is connected to a suitable actuator. The upper part of the center hub (2s) also has a symmetrical structure, and adduction motion can be achieved by the MP adduction segment pulley (2f) equipped with a post (2fa). The MP abduction wire and MP adduction wire are routed in a staggered X-shape to increase the range of motion.

[0040] Figure 17 shows an exploded view of the base frame (3) and the double pulley (19) that fits with it. Figure 15, which has already been shown, corresponds to this structure. The left side (3s) and the right side (3t) of the base frame are equipped with drive shafts including a fitting portion (219) for the connecting shaft (19). The drive shafts are equipped with fastening holes through which screws pass, and they fit with the drive shaft of the double pulley (19). By passing a bolt (220) through the fastening hole and fixing it with a nut (221), the torque of the double pulley (19) can be transmitted to the base frame (3).

[0041] Figure 18 shows a view of the base frame (3) from an oblique front angle. Behind the PIP wire window (224) and DIP wire window (225), the grooves of the third PIP pulley (222) and the third DIP pulley (223) shown in Figure 15 are visible, indicating that the wires are routed without contacting the base frame (3).

[0042] Using the above mechanism, when directly driving the flexion / extension axis and adduction axis of the MP joint, the DIP joint and PIP joint can be wire-driven without interference or interference, while providing the necessary passive torque.

Claims

[Claim 1] A mechanism comprising a fixed frame, a middle section, a proximal frame, a DIP wire, a PIP wire, an MP abduction wire, an MP adduction wire, and an MP flexion / extension wire, having the following features (1) to (8): (1) The fixed frame includes a bearing, an MP forward wire hole, an MP reverse wire hole, a DIP wire hole, a PIP wire hole, an MP abductor wire hole, and an MP internal wire hole, and is rotatably equipped with an MP internal pulley and an MP abductor pulley. (2) The center spinning top comprises a rotating shaft, first, second and third DIP pulleys, first, second and third PIP pulleys, first and second MP forward-rotating pulleys, first and second MP reverse-rotating pulleys, an MP double pulley, an MP external segment pulley including a post, and an MP internal segment pulley including a post, wherein the rotating shaft is fitted into a bearing of the fixed frame, the second DIP pulley protrudes from the side end face of the center spinning top, the second PIP pulley protrudes from the side end face of the center spinning top, and the MP double pulley comprises a connecting shaft and a wire intermediate fixing mechanism. (3) The base frame comprises a drive shaft including a fitting portion, a DIP wire window, and a PIP wire window, the fitting portion of the drive shaft fitting with the connecting shaft of the MP double pulley to transmit power. (4) The DIP wire passes through the DIP wire hole, wraps around the first DIP pulley once, is guided by the second DIP pulley, is guided by the third DIP pulley, and passes through the DIP wire window. (5) The PIP wire passes through the PIP wire hole, wraps around the first PIP pulley once, is guided by the second PIP pulley, is guided by the third PIP pulley, and passes through the PIP wire window. (6) The MP abductor wire is fixed to the post at one end, guided by the MP abductor segment pulley, passes through the MP abductor wire hole, and is guided by the MP abductor pulley. (7) The MP inner wire is fixed to the post, guided by the MP inner segment pulley, passes through the MP inner wire hole, and is guided by the MP inner pulley. (8) The MP bending wire passes through the MP forward wire hole, wraps around the first MP forward pulley once, is guided to the second MP forward pulley, is guided to the forward pulley of the MP double pulley, and while the middle portion of the wire is fixed, it passes to the reverse pulley of the MP double pulley, is guided to the reverse pulley, is guided to the second MP reverse pulley, wraps around the first MP reverse pulley once, and passes through the MP reverse wire hole.

Images