JP7819945B2 - Robotic hand with multi-jointed fingers - Google Patents

Description

The present invention relates to a robotic hand, in particular a robotic hand with multi-jointed fingers.

Manipulators and robotic hands (hereafter referred to as "robot hands") equipped with multi-jointed fingers have been developed and are used in manufacturing sites, etc. In particular, robotic hands that mimic the human hand have been proposed for use in prosthetic hands and, in recent years, as remote communication tools.

Typically, such robotic hands have their joints initially extended, and then each joint is displaced into a bent state by the driving force of an actuator or the like. Various methods for transmitting driving force to each joint have been proposed, including a method in which each joint is provided with a pulley and the driving force is transmitted by a wire wound around the pulley (e.g., Patent Document 1), a method in which individual driving forces are transmitted to each joint (e.g., Patent Document 2), a method in which driving force is transmitted by a wire threaded through each finger member (e.g., Patent Document 3), and a method in which driving force is transmitted by a link mechanism (Patent Document 4).

Japanese Unexamined Patent Publication No. 7-096485 JP 2012-016784 A Japanese Patent Application Laid-Open No. 2019-076786 Japanese Patent Application Laid-Open No. 2019-093457

With the robot hand described above, driving forces are transmitted to each finger member and joint, causing the joints to bend, making it possible to clamp objects during the manufacturing process. However, depending on the intended use, such as when using a robot hand as a prosthetic hand or communication tool, it may be desirable to freely control the order in which the finger joints bend, or to control the movement so that it resembles that of human finger joints.

To solve these problems, the robot hand in Patent Document 1 is equipped with a clutch/brake on each pulley, and the bending of each joint is controlled by controlling the opening and closing of each clutch/brake. The robot hand in Patent Document 2 is equipped with individual motors that supply driving force to each joint, and these are controlled individually. However, these robot hands have complex control and structures, and are difficult to miniaturize.

In contrast, the robot hand in Patent Document 3 varies the magnitude of the rotational moment acting on each joint. Because of this configuration, when the wire is pulled and a bending force acts on the joints, the joints are displaced into a bent state in order of the largest rotational moment. This allows multiple joints to be displaced into a bent state in a specified order.

However, depending on the orientation of the palm of the robot hand, the magnitude of the rotational moment acting on each joint may differ from the theoretical value, which may make it impossible to bend multiple joints in the desired order.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a robotic hand with multi-jointed fingers that is capable of flexing or extending multiple finger joints in a specified order with a simple configuration.

In order to solve the above problems, the present invention provides a robot hand with multi-jointed fingers, the multi-jointed fingers comprising at least a first finger portion, a second finger portion, and a third finger portion, the second finger portion being connected to a vicinity of a fingertip-side end of the first finger portion so as to be rotatable about a first rotation axis to form a first joint that can be bent/extended, the third finger portion being connected to a vicinity of a fingertip-side end of the second finger portion so as to be rotatable about a second rotation axis to form a second joint that can be bent/extended, a bending force application portion that applies a bending force to the first joint and the second joint, and a spring that is provided near the first joint and generates an extension force that resists the bending force acting on the first joint. and a second elastic body that is a spring that is provided near the second joint and generates an extension force that resists the bending force acting on the second joint, wherein the extension force of the second elastic body is smaller than the extension force of the first elastic body, and the first elastic body is formed by being fixed to the first finger portion and the second finger portion so as to straddle the first joint, and the second elastic body is formed by being fixed to the second finger portion and the third finger portion so as to straddle the second joint, wherein the number of turns of the second elastic body is smaller than the number of turns of the first elastic body, and the spring constant of the second elastic body is smaller than the spring constant of the first elastic body .

In this configuration, the extension force of the second elastic body disposed near the second joint is smaller than the extension force of the first elastic body disposed near the first joint. Therefore, when the bending force application unit applies a bending force to each joint, the second joint bends more easily than the first joint. Therefore, by designating the joint to be bent first as the second joint and the joint to be bent later as the first joint, the joints can be bent in a specified order. Even when there are three or more joints, the joints can be bent in a specified order by similarly setting the extension forces of the elastic bodies. Furthermore, in this configuration, portions of a single coil spring can be used as the first elastic body and the second elastic body, resulting in a simple configuration. In this case, the magnitude of the extension force can be set as the spring constant of the elastic body (spring), and the spring constant of the elastic body (spring) can be set as the number of turns.

In one preferred embodiment of the robot hand according to the present invention, the coil spring is a compression coil spring provided on the palm side and the bending force application portion is a wire, or the coil spring is a tension coil spring provided on the back side of the hand and includes a wire that applies an extension force to the first joint and the second joint, and the wire is inserted into the coil spring.

This configuration is equipped with a wire that applies a bending or extension force to the joints of the multi-jointed finger. Such a wire needs to be attached so that it does not get caught on other components or surrounding objects during use. In this configuration, the wire is inserted into a coil spring that serves as an elastic body, so it is possible to prevent snagging without using other components, resulting in a simple configuration.

A robot hand with multi-jointed fingers according to the present invention includes a multi-jointed finger including at least a first finger portion, a second finger portion, and a third finger portion, the second finger portion being connected to the vicinity of a fingertip-side end of the first finger portion so as to be rotatable about a first rotation axis to form a first joint that can be bent/extended, the third finger portion being connected to the vicinity of a fingertip-side end of the second finger portion so as to be rotatable about a second rotation axis to form a second joint that can be bent/extended, a bending force application portion that applies a bending force to the first joint and the second joint, and a first spring that is provided across both ends of the first joint, generates an extension force that resists the bending force acting on the first joint, and applies a biasing force in the extension direction to the first joint. and a second elastic body which is a spring provided across both ends of the second joint, generating an extension force that resists the bending force acting on the second joint, and applying a biasing force to the second joint in the extension direction, wherein the extension force of the second elastic body is smaller than the extension force of the first elastic body, the spring constant of the second elastic body is smaller than the spring constant of the first elastic body, the springs which are the first elastic body and the second elastic body are fixed only at both ends and have an exposed middle portion, the springs which are the first elastic body and the second elastic body are compression coil springs provided on the palm side, the bending force acting portion is a wire, and the wire is inserted into the compression coil spring.

In this configuration, the extension force of the second elastic body disposed near the second joint is smaller than the extension force of the first elastic body disposed near the first joint. Therefore, when the bending force application unit applies a bending force to each joint, the second joint bends more easily than the first joint. Therefore, by designating the joint to be bent first as the second joint and the joint to be bent later as the first joint, the joints can be bent in a predetermined order. Even when there are three or more joints, the joints can be bent in a predetermined order by similarly setting the extension forces of the elastic bodies. Furthermore, in this configuration, the first and second elastic bodies are fixed only at their ends, and their intermediate portions are exposed. Therefore, when a tensile force acts on the wire and the joint bends, these elastic bodies can be displaced inward (toward the palm). This displacement of the elastic bodies slightly reduces the curvature of the wire, reducing the tendency for the wire to bend.

FIG. 1 is a perspective view of a robot hand. FIG. 1 is an exploded perspective view of the index finger of the robot hand in an extended state. FIG. 3A is a perspective view of the index finger of the robot hand, and FIG. 3B is a cross-sectional view of the index finger of the robot hand taken along line III-III. FIG. 10 is a side cross-sectional view showing the bending action of the index finger. FIG. 2 is a side cross-sectional view of the index finger of the robot hand in Example 1. FIG. 10 is a side cross-sectional view of the index finger of the robot hand in Example 2. FIG. 11 is a side cross-sectional view of the index finger of the robot hand in Example 3. FIG. 10 is a side cross-sectional view of the index finger of the robot hand in Example 4. This is an enlarged view of the vicinity of a bent joint.

An embodiment of a robot hand according to the present invention will be described below with reference to the drawings. Figure 1 is a perspective view of a robot hand with multi-jointed fingers according to this embodiment (hereinafter abbreviated as robot hand H). As shown in the figure, robot hand H is modeled after a human hand, and has five multi-jointed fingers F1, F2, F3, F4, and F5 corresponding to the thumb, index finger, middle finger, ring finger, and little finger. In the following description, when it is not necessary to distinguish between these, they will be referred to as fingers F. On the other hand, when it is necessary to distinguish between them, they may be referred to as thumb F1, etc.

As mentioned above, the robot hand H in this embodiment is modeled after a human right hand and has five fingers F, but the number of fingers F can be changed as appropriate depending on the application. The number of joints can also be changed as appropriate.

Figure 1 shows a robot hand H with the palm facing up. Each finger, except for the thumb F1, has a metacarpal 11, a proximal phalanx 12, a middle phalanx 13, and a distal phalanx 14. The metacarpal 11 and proximal phalanx 12 are arranged adjacent to each other in the longitudinal direction and are connected to each other so that they can rotate. This connection is the MP joint 21. The proximal phalanx 12 and middle phalanx 13 are similarly connected to form a PIP joint 22, and the middle phalanx 13 and distal phalanx 14 are also connected to form a DIP joint 23. The thumb F1 has a similar configuration, but does not have a middle phalanx 13. Instead, the proximal phalanx 12 and distal phalanx 14 are connected to form an IP joint 24. By allowing the joints of each finger F to rotate in this way, the fingers F can be flexed and extended.

The metacarpals 11 of the index finger F2, middle finger F3, ring finger F4, and little finger F5 are inserted and fixed to the base member 3 located near the wrist. Specifically, in a plan view, adjacent metacarpals 11 are not parallel to each other, but are fixed at an angle so that the fingertips are apart. The metacarpal 11 of the thumb F1 is fixed to the end of the base member 3 on the index finger F2 side via a thumb support member 31.

Next, the structure of the finger F in this embodiment will be described using Figure 2. Figure 2 is an exploded perspective view of the index finger F2 in an extended state. As mentioned above, the structure of each finger F is basically the same, although there are differences in size and the thumb F1 mentioned above. Therefore, the structure of the index finger F2 will be described here.

Like human fingers, the index finger F2 comprises a metacarpal bone 11, a proximal phalanx 12, a middle phalanx 13, and a distal phalanx 14. The metacarpal bone 11 is composed of an elongated, approximately rectangular, plate-shaped metacarpal bone plate 11a and a retaining member 11c arranged on both sides of the metacarpal bone plate 11a at the wrist end. The proximal phalanx 12 is composed of an elongated, approximately rectangular, plate-shaped proximal phalanx inner plate 12a, retaining members 12c arranged on both sides of the proximal phalanx inner plate 12a, and a plate-shaped proximal phalanx outer plate 12b arranged on the outer surface of each retaining member 12c. The middle phalanx 13 is similarly composed of an elongated, approximately rectangular, plate-shaped middle phalanx inner plate 13a, retaining members 13c arranged on both sides of the middle phalanx inner plate 13a, and a plate-shaped middle phalanx outer plate 13b arranged on the outer surface of each retaining member 13c. The distal phalanx 14 is composed of a distal phalanx inner plate 14a and plate-like distal phalanx outer plates 14b arranged on both sides of the distal phalanx inner plate 14a.

As shown in Figure 1, the wrist-side end of the metacarpal plate 11a is inserted into the insertion hole 3a of the base member 3. With the metacarpal plate 11a in this inserted state, the fixing members 4 are screwed from the front and rear of the insertion direction and from the thickness direction of the metacarpal plate 11a. This fixes the first finger plate 11a to the base member 3. Note that the screws are omitted in Figures 1 and 2.

The proximal phalanx inner plate 12a is positioned at the fingertip-side end of the metacarpal plate 11a, followed by the middle phalanx inner plate 13a and the distal phalanx inner plate 14a, which are positioned in order with their axes aligned. A pair of clamping members 11c, 12c, and 13c are positioned on either side of the metacarpal plate 11a, proximal phalanx inner plate 12a, and middle phalanx inner plate 13a, sandwiching each of them. The length of clamping member 11c is approximately the same as the fixing member 4, and it is clamped and fixed by the fixing member 4 on the fingertip side of the metacarpal plate 11a. The length of clamping member 12c is slightly shorter than the length of the proximal phalanx inner plate 12a, and is positioned so that the wrist-side end of clamping member 12c is aligned with the wrist-side end of the proximal phalanx inner plate 12a. Similarly, the length of the retaining member 13c is slightly shorter than the length of the middle phalanx inner plate 13a, and the end of the retaining member 13c on the wrist side is positioned so as to coincide with the end of the middle phalanx inner plate 13a on the wrist side.

A proximal phalanx outer plate 12b is disposed on the outer surface of each retaining member 12c, and the proximal phalanx outer plate 12b, together with the retaining member 12c, is screwed to the proximal phalanx inner plate 12a. A support shaft (not shown) is inserted through the shaft hole 12bh of the proximal phalanx outer plate 12b closest to the wrist, and this support shaft is supported by a bearing (not shown) inserted into the hole 11ah of the metacarpal plate 11a closest to the fingertip. This connects the proximal phalanx 12 to the metacarpal 11 so that it can rotate around the rotation axis A1. This rotatable connection also forms the MP joint 21, which can flex and extend.

Similarly, the middle phalanx 13 has an outer phalanx plate 13b positioned on the outer surface of each retaining member 13c, and the outer phalanx plate 13b is screwed together with the retaining member 13c to the inner phalanx plate 13a. A support shaft (not shown) is inserted through the shaft hole 13bh of the outer phalanx plate 13b closest to the wrist, and this support shaft is supported by a bearing (not shown) inserted in the hole 12ah of the inner proximal phalanx plate 12a closest to the fingertip. This connects the middle phalanx 13 to the proximal phalanx 12 so that it can rotate around the rotation axis A2. This rotatable connection also forms a PIP joint 22 that can flex and extend.

A support shaft (not shown) is inserted through shaft hole 14bh in the distal phalanx outer plate 14b, which is closest to the wrist, and this support shaft is supported by a bearing (not shown) inserted in hole 13ah in the middle phalanx inner plate 13a, which is closest to the fingertip. This connects the distal phalanx 14 to the middle phalanx 13 so that it can rotate around rotation axis A3. This rotatable connection forms a DIP joint 23, which can flex and extend.

Figure 3(a) is a perspective view of the index finger F2, and Figure 3(b) is a cross-sectional view taken along III-III in Figure 3(a), showing the cross-section of the proximal phalanx 12 of the index finger F2. As shown in the figure, the pressing member 12c has a roughly U-shaped cross-section and comprises a side plate 51, an upper plate 52, and a lower plate 53. A gap is formed between the upper inner surface 52a of the upper plate 52 and the upper surface of the proximal phalanx inner plate 12a, forming a passage P. A similar gap (passage P) is also formed between the lower inner surface 53a of the lower plate 53 and the lower surface of the proximal phalanx inner plate 12a. Similarly, passages P are formed above and below the middle phalanx 13.

Although not shown in Figures 1 to 3, the fingers F of the robot hand H according to the present invention are provided with elastic bodies that apply different extension forces to the positions of each joint. Therefore, when a bending force acts on each joint, the magnitude of bending or extension of each joint differs depending on the difference in the extension force, and the order in which they bend or extend varies.

Figures 4(a) to (d) are side cross-sectional views showing the bending movement of the index finger F2 in chronological order. The cross-sectional position is the front side of the metacarpal plate 11a, and is indicated by IV-IV in Figure 3(a). The side cross-sectional views in the following examples also have the same cross-sectional position. Note that the elastic body is not shown in Figure 4, as it will be explained in the following examples.

In this embodiment, wires W1 and W2 are provided on the back side of the hand (upper side in the figure) and the palm side (lower side in the figure). Wires W1 and W2 are inserted through a passage P shown in FIG. 3 from the wrist toward the fingertips, with one end fixed to the distal phalanx 14 and the other end connected to an actuator or the like (not shown). When a tensile force (force toward the right in the figure) is applied to wire W1 by an actuator or the like, finger F attempts to extend. On the other hand, when a tensile force (force toward the right in the figure) is applied to wire W2 (an example of a bending force application portion in the present invention), finger F attempts to bend toward the palm. To bend finger F, the tensile force on wire W1 must be loosened or released. As described above, because wires W1 and W2 are inserted through passage P, they are less likely to get caught on other components or surrounding objects even if they become loose. Note that wires W1 and W2 can be made of any material capable of transmitting a tensile force from an actuator or the like, such as wire or fishing line.

As described above, when wire W1 is loosened and a tensile force is applied to wire W2, as shown in this figure, finger F appears to bend in the order of DIP joint 23, PIP joint 22, and MP joint 21. Naturally, the order in which the joints bend can be changed as appropriate, and it is also possible to bend finger F in the order of MP joint 21, PIP joint 22, and DIP joint 23.

Figure 5(a) is a side cross-sectional view of the index finger F2 in this embodiment. In the side cross-sectional views of this embodiment and subsequent figures, the palm side is facing downward. As shown in the figure, springs 61, 62, and 63 (examples of the first elastic body and second elastic body in this invention) are provided on the palm sides of the MP joint 21, PIP joint 22, and DIP joint 23, respectively. Specifically, spring 61 is a compression coil spring, sandwiched between the fingertip-side end face of presser member 11c and the wrist-side end face of presser member 12c, exerting a biasing force on the MP joint 21 in the extension direction. Spring 62 is also a compression coil spring, sandwiched between the fingertip-side end face of presser member 12c and the wrist-side end face of presser member 13c, exerting a biasing force on the PIP joint 22 in the extension direction. The spring 63 is also a compression coil spring, and is arranged so as to be sandwiched between the end face of the pressing member 13c on the fingertip side and the end face of the distal phalanx inner plate 14a on the wrist side, and applies a biasing force to the DIP joint 23 in the extension direction.

The wire W2 is inserted through the passage P and the springs 61, 62, and 63. Therefore, the wire W2 is hardly exposed to the outside, making it less likely to get caught on other components.

If the spring constants of springs 61, 62, and 63 are k1, k2, and k3, respectively, then k1 > k2 > k3. Therefore, when a tensile force is applied to wire W2, spring 63 compresses most easily and spring 61 compresses least easily for the same force. This allows the DIP joint 23, PIP joint 22, and MP joint 21 to bend in that order.

Although compression coil springs are used as springs 61, 62, and 63, leaf springs may also be used.

As a modification of this embodiment, as shown in Figure 5(b), springs 61, 62, and 63 can be replaced by a single spring 6. In this modification, spring 6 is provided from the fingertip-side end face of retainer member 11c to the wrist-side end face of distal phalanx inner plate 14a. Spring 6 is inserted through passage P in the proximal phalanx 12 and middle phalanx 13 areas.

In this modified example, spring 6 is fixed at both ends of each joint, with the portions between these fixed positions representing springs 61, 62, and 63. That is, the portion from the fixed position at metacarpal bone 11 to the fixed position at proximal phalanx 12 corresponds to spring 61, the portion from the fixed position at proximal phalanx 12 to the fixed position at middle phalanx 13 corresponds to spring 62, and the portion from the fixed position at middle phalanx 13 to the fixed position at distal phalanx 14 corresponds to spring 63. In this case, springs 61, 62, and 63 are fixed with different numbers of turns so that the spring constants of the springs satisfy the above-mentioned relationship. The number of turns can be changed by changing the interval at which they are fixed or by stretching the fixed portions, etc.

In this way, by placing springs 61, 62, and 63 with different spring constants in the joint area on the palm side, the joint can be bent in order, starting with the spring with the smallest spring constant. Furthermore, even if an extremely large tensile force acts on wire W2, springs 61, 62, and 63 will prevent bending beyond a certain level, preventing accidents such as crushing an object.

Furthermore, when wire W2 is released while each joint is bent, springs 61, 62, and 63 elastically return, and each joint is displaced to an extended state. At this time, the order in which the joints extend is determined by the magnitude of the spring constants. Specifically, the MP joint 21, which has the spring 61 with the largest spring constant, extends first, followed by the PIP joint 22 and the DIP joint 23. In other words, not only the bending order but also the extension order can be controlled by the magnitude of the spring constant of the elastic body arranged in each joint.

If the metacarpal bone 11 is considered the first finger portion in this invention, then the proximal phalanx 12 corresponds to the second finger portion, the middle phalanx 13 corresponds to the third finger portion, the MP joint 21 corresponds to the first joint, the PIP joint 22 corresponds to the second joint, the rotation axis A1 corresponds to the first rotation axis, the rotation axis A2 corresponds to the second rotation axis, the spring 61 corresponds to the first elastic body, and the spring 62 corresponds to the second elastic body. Alternatively, the proximal phalanx 12 can be considered the first finger portion in this invention, in which case the middle phalanx 13 corresponds to the second finger portion, the distal phalanx 14 corresponds to the third finger portion, the PIP joint 21 corresponds to the first joint, the DIP joint 23 corresponds to the second joint, the rotation axis A2 corresponds to the first rotation axis, the rotation axis A3 corresponds to the second rotation axis, the spring 62 corresponds to the first elastic body, and the spring 63 corresponds to the second elastic body. This also applies to the following examples.

Figure 6(a) is a side cross-sectional view of the index finger F2 in this embodiment. In this embodiment, as shown in the figure, springs 61, 62, and 63 (examples of the first elastic body and second elastic body in the present invention) are provided on the back side of the MP joint 21, PIP joint 22, and DIP joint 23, respectively. The placement of springs 61, 62, and 63 is the same as in Example 1, except for whether they are on the back or palm side of the hand. However, in this embodiment, springs 61, 62, and 63 are tension coil springs, and apply a tensile force in the extension direction to each joint of the finger F. Wire W1 is inserted through springs 61, 62, and 63. Wire W1 needs to be loosened when bending the finger F, but by inserting it through springs 61, 62, and 63, it is less likely to get caught on other components.

Springs 61, 62, and 63 have spring constants k1, k2, and k3, respectively, such that k1 > k2 > k3. Therefore, when a tensile force is applied to wire W2, it bends in the order of DIP joint 23, PIP joint 22, and MP joint 21, as described above.

Although compression coil springs are used as springs 61, 62, and 63, leaf springs may also be used.

As with the modified example of Example 1, as a modified example of this example, springs 61, 62, and 63 can be replaced by a single spring 6, as shown in Figure 6(b).

In this way, by placing springs 61, 62, and 63 with different spring constants at the joint portion on the back of the hand, the joints can be bent in order starting from the joint where the spring with the smallest spring constant is placed.

In the case of Examples 1 and 2, springs 61, 62, and 63 apply a biasing force or a tensile force in the direction of extending the joint, so the wire W1 may be omitted. Furthermore, if wire W1 is provided, when the tensile force of wire W2 is released, the action of springs 61, 62, and 63 displaces each joint into an extended state, so wire W1 can be used as an auxiliary force, and there is no need to maintain the tension of wire W1.

Figure 7 is a side cross-sectional view of the index finger F2 in this embodiment. In this embodiment, in order to approximate the feel of a human hand, the robot hand H is covered with an elastic covering 7 that mimics the muscles, skin, etc. of a human hand. The elastic covering 7 can be made of a material that elastically deforms while generating an appropriate repulsive force when the finger F is bent, such as rubber, silicone rubber, or urethane gel. Note that the repulsive force is a force that resists tensile force on the back of the hand, and a force that resists compressive force on the palm.

In this embodiment, the thickness of each joint portion of the elastic covering body 7 on the palm side is varied to vary the repulsive force acting on each joint and control the order in which the joints bend. In this embodiment, recesses 71, 72, and 73 are formed on the palm side of the elastic covering body 7 at the MP joint 21, PIP joint 22, and DIP joint 23, respectively, to vary the thickness of each joint portion of the elastic covering body 7. Specifically, by making recess 73 the largest and recess 71 the smallest, the thickness of the elastic covering body 7 near the DIP joint 23 is the thinnest and the thickness of the elastic covering body 7 near the MP joint 21 is the thickest. This results in the smallest repulsive force near recess 73 and the largest repulsive force near recess 71. When a tensile force is applied to the wire W2 of this index finger F2, the DIP joint 23, which has the largest recess, begins to bend first, followed by the PIP joint 22 and MP joint 21.

Naturally, the method for varying the repulsive force is not limited to this, and can be modified as long as the objective of the present invention is achieved, such as by partially changing the hardness of the covering elastic body 7. It is also possible to use springs 61, 62, and 63 in Examples 1 and 2 in combination. In this case, the repulsive force of the covering elastic body 7 can be set taking into account the spring constants of springs 61, 62, and 63.

In this embodiment, the MP joint 21 can be maintained in an extended state, and only the PIP joint 22 and DIP joint 23 can be flexed. Figure 8 is a side cross-sectional view showing the flexion movement of the index finger F2 in this embodiment. In this embodiment, the index finger F2 is equipped with a wire W3 that applies a tensile force to the proximal phalanx 12. One end of the wire W3 is fixed to the proximal phalanx 12 near the back of the hand, closer to the metacarpal bone 11, and the other end is connected to an actuator or the like (not shown). Note that other components such as the first elastic body and second elastic body are not shown in Figure 8, as they can be those of any of the above-mentioned embodiments.

When wire W2 is pulled on an index finger F configured as described above while a tensile force is applied to wire W3, the DIP joint 23, which is easiest to bend, bends first (Figure 8(a)), followed by the PIP joint 22 (Figure 8(b)). Further pulling on wire W2 bends the MP joint 21 in the above-described embodiment, but in this embodiment, the tensile force of wire W3 inhibits bending of the MP joint 21, so only the DIP joint 23 and PIP joint 22 continue to bend (Figures 8(c)-(e)). Furthermore, by controlling the tensile force of W3, the MP joint 21 can be bent once the DIP joint 23 and PIP joint 22 reach a predetermined bent position.

In this way, the configuration of this embodiment allows the flexion of the MP joint 21 to be controlled independently from the flexion of other joints.

As described above, the bending order of the joints of the fingers F of the robot hand H according to the present invention can be controlled by the difference in elastic force of the elastic bodies (first elastic body, second elastic body) provided at each joint portion. Furthermore, if springs are used as the first elastic body and second elastic body, they can be used as a passage for a wire that applies a tensile force to the fingers F. In this case, it is possible to prevent the wire from getting caught on other members or surrounding objects.

When metal wires are used for wire W1 and wire W2, there is a risk that the wires may develop a tendency to bend with repeated use. The greater the bending of the wire during use, the more likely it is that this tendency will develop. In other words, wire W2 arranged on the palm side of the hand is more likely to develop a tendency to bend than wire W1 arranged on the back side of the hand. The above-described embodiment also shows a solution to this problem. Specifically, at each joint, springs 61, 62, and 63, which serve as the passage for wire W2, are fixed only at both ends, with the middle portion exposed. Therefore, when a tensile force acts on wire W2 and the joint bends, these springs can be displaced inward. This displacement of the springs slightly reduces the curvature of wire W2, reducing the likelihood of it developing a tendency to bend.

This effect depends on the length of the spring attached to the joint from its fixed position on the wrist side to its fixed position on the fingertip side. Specifically, the longer the length from the fixed position on the wrist side to its fixed position on the fingertip side, the smaller the curvature of the wire W2 can be. Figure 9 is a cross-sectional view of the PIP joint 22 and its vicinity in a bent state, showing the change in the spring's curvature. Note that the spring 62 is hatched in Figure 9 for easy identification. Figure 9(a) shows the state in which the spring 62 is fixed to the front end of the presser member 12c and the rear end of the presser member 13c. Figure 9(b) shows the state in which the spring 62 is fixed to the front end of the presser member 12c and the fingertip-side end surface of the recess formed at the rear end of the presser member 13c. Figure 9(c) shows the state in which the spring 62 is fixed to the wrist-side end surface of the recess formed at the front end of the presser member 12c and the fingertip-side end surface of the recess formed at the rear end of the presser member 13c. As shown in these figures, the longer the length from the fixed position on the wrist side of the spring to the fixed position on the fingertip side, the smaller the curvature of the spring 62 and the smaller the curvature of the wire W2 passing through it.

Furthermore, the robot hand H according to the present invention can easily perform finger snapping, which was difficult with conventional robot hands. For example, if the joints of the index finger F2 in the above-described embodiment are bent and the thumb F1 is pressed against the distal phalanx 14 to prevent extension, and the thumb F1 is then shifted, the restoring force of the springs 61 and other springs causes each joint to vigorously extend, resulting in a finger snapping motion.

[Another embodiment]
(1) In the above embodiment, the finger F is displaced from an extended state to a bent state, but it may be displaced from a bent state to an extended state. In this case, too, the order in which the joints are extended can be controlled by varying the elastic force acting on each joint, as in the above embodiment.

(2) In the above-described first and second embodiments, springs 61, 62, and 63 are provided in the MP joint 21, the PIP joint 22, and the DIP joint 23. However, it is also possible to configure the joint that is desired to bend most quickly without providing an elastic body (such as a spring). For example, it is also possible to configure the DIP joint 23 in the first and second embodiments without providing the spring 63.

(3) The above-described embodiments may be modified as appropriate and may be combined with each other as long as the objective of the present invention is achieved.

The present invention can be used not only in conventional applications such as manufacturing sites and prosthetic hands, but also in remote communication systems. In such a remote communication system, for example, a robotic hand H according to the present invention and a monitor are installed at a first location where a first user is located, and a sensor capable of detecting hand movements, such as a data glove, and a camera are installed at a second location where a second user is located. Images captured by the camera at the second location are displayed on a monitor at the first location, allowing the first user to visually recognize the second user. Furthermore, when the sensor at the second location detects the second user's hand-clenching motion, this information is reflected in the movement of the robotic hand H at the first location, and the robotic hand H bends the joints of each finger F as if to grasp the first user's hand. Using such a remote communication system enables simulated physical contact, enhancing a sense of closeness despite being physically distant from one another.

A1: Rotation axis A2: Rotation axis A3: Rotation axis H: Robot hand F: Finger (multi-joint finger)
F1: Thumb (multi-jointed finger)
F2: Index finger (multi-jointed finger)
F3: Middle finger (multi-jointed finger)
F4: Ring finger (multi-jointed finger)
F5: Little finger (multi-jointed finger)
W1: Wire rod W2: Wire rod (bending force acting part)
11: Metacarpal 12: Proximal phalanx 13: Middle phalanx
14: Distal phalanx 21: MP joint 22: PIP joint 23: DIP joint 24: IP joint 6: Spring (first elastic body, second elastic body)
61: Spring 62: Spring 63: Spring 7: Covered elastic body

Claims (3)

A robotic hand with articulated fingers,
The multi-joint finger includes at least a first finger portion, a second finger portion, and a third finger portion,
the second finger portion is connected to the first finger portion near a fingertip side end portion so as to be rotatable around a first rotation axis, thereby forming a first joint that can be bent/extended;
the third finger portion is connected to the vicinity of the fingertip side end of the second finger portion so as to be rotatable around a second rotation axis, thereby forming a second joint that is flexible/extendable;
a bending force application unit that applies a bending force to the first joint and the second joint;
a first elastic body that is a spring provided near the first joint and that generates an extension force that resists the bending force acting on the first joint;
a second elastic body that is a spring provided near the second joint and that generates an extension force that resists the bending force acting on the second joint,
the extension force of the second elastic body is smaller than the extension force of the first elastic body;
a single coil spring that is fixed to the first finger portion and the second finger portion so as to straddle the first joint and constitutes the first elastic body, and that is fixed to the second finger portion and the third finger portion so as to straddle the second joint and constitutes the second elastic body;
A robot hand in which the number of turns of the second elastic body is smaller than the number of turns of the first elastic body, and the spring constant of the second elastic body is smaller than the spring constant of the first elastic body . the coil spring is a compression coil spring provided on the palm side, and the bending force application portion is a wire material, or the coil spring is a tension coil spring provided on the back side of the hand, and includes a wire material that applies an extension force to the first joint and the second joint,
2. The robot hand according to claim 1 , wherein the wire is inserted through the coil spring. A robotic hand with articulated fingers,
The multi-joint finger includes at least a first finger portion, a second finger portion, and a third finger portion,
the second finger portion is connected to the first finger portion near a fingertip side end portion so as to be rotatable around a first rotation axis, thereby forming a first joint that can be bent/extended;
the third finger portion is connected to the vicinity of the fingertip side end of the second finger portion so as to be rotatable around a second rotation axis, thereby forming a second joint that is flexible/extendable;
a bending force application unit that applies a bending force to the first joint and the second joint;
a first elastic body that is a spring provided across both ends of the first joint, generating an extension force that resists the bending force acting on the first joint, and applying a biasing force in an extension direction to the first joint;
a second elastic body that is a spring that is provided across both ends of the second joint, generates an extension force that resists the bending force acting on the second joint, and applies a biasing force in an extension direction to the second joint,
the extension force of the second elastic body is smaller than the extension force of the first elastic body;
the spring constant of the second elastic body is smaller than the spring constant of the first elastic body;
The springs, which are the first elastic body and the second elastic body, are fixed only at both ends and have an exposed middle portion,
the first elastic body and the second elastic body are compression coil springs provided on the palm side, and the bending force acting portion is a wire rod;
The wire is inserted into the compression coil spring.