JP2005090562A - Link-type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and light link type continuously variable transmission capable of obtaining a large reduction gear ratio and to be used for a driving system for driving a movable body limited in movable range thereof such as a robot hand, especially fingers of a multi-finger robot hand. <P>SOLUTION: The link type continuously variable transmission is provided with a base link member 10, an input link member 12 pivotally fitted to one end of the base link member 10 at a first pivotal fitting point and having link length to be continuously changed, an output link member 14 pivotally fitted to the other end of the base link member at a second pivotal fitting point, and an intermediate link member 16 pivotally fitted to the input link member and the output link member to face to the base link member. The input torque t<SB>in</SB>input to turn the input link member around the first pivotal fitting point is converted to the output torque t<SB>out</SB>for turning the output link member around the second pivotal fitting point, and as link length of the input link member becomes shorter, torque ratio of the output torque in relation to the input torque is gradually increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention generally relates to a link type continuously variable transmission, and more specifically, a link that can be advantageously applied to a finger drive system of a movable body having a limited movable range, such as a robot hand, particularly a multi-finger robot hand. The present invention relates to a continuously variable transmission.

  As is well known, in the drive system of a multi-fingered robot hand, not only a certain level of speed is required for the movement of individual fingers, but it is also suitable for ensuring the reliable gripping of objects by the multi-fingered hand. A strong gripping force is also required.

  Proposals for increasing the speed of finger movement in a multi-fingered robot hand are disclosed in Non-Patent Documents 1 and 2, for example. In addition, there is a trade-off relationship between the speed of the finger and the gripping force in the reduction ratio, and thus satisfies the two requirements of increasing the gripping force while increasing the speed of finger movement in a multi-fingered robot hand. It was said that it was extremely difficult to make it happen.

Akio Namiki et al. “Development of lightweight high-speed robot finger module” The Japan Society of Mechanical Engineers Robotics Mechatronics Lecture '02 Proceedings, 2P2-F04, 2002 Tetsuya Mouri et al. “Humanoid Robot Hand“ Gifu Hand III ”and its Real-time Control System” The Japan Society of Mechanical Engineers Robotics Mechatronics Lecture '02 Proceedings, 2P2-F02, 2002

  In order to increase the gripping force of fingers with a small actuator in a multi-fingered robot hand, as a transmission, reduce the reduction ratio when opening and closing the finger to increase the speed of the finger, and increase the reduction ratio when gripping an object. Thus, a device capable of obtaining a large gripping force is required. In recent years, in the field of robotics, as disclosed in Non-Patent Documents 3 and 4, load-sensitive continuously variable transmissions that are smaller and lighter than automobile transmissions have been developed. However, such a continuously variable transmission is still large and too heavy to be incorporated into a multi-fingered robot hand. That is, a small and lightweight transmission that can be incorporated into a multi-fingered robot hand has not yet been developed.

"Development of load-sensitive continuously variable transmission X-screw" by Shigeo Hirose et al., Transactions of the Japan Society of Mechanical Engineers (C), Vol. 66, No. 646, pp. 1912-1916, 2000 Tetsuo Hagiwara et al. “Development of rotary load-sensitive continuously variable transmission, part 1 Proposal of basic mechanism” The Japan Society of Mechanical Engineers Robotics Mechatronics Lecture '01 Proceedings, 1A1-M2, 2001

  Accordingly, an object of the present invention is a small and light link type continuously variable transmission that can be applied to a finger drive system of a movable body having a limited movable range, for example, a robot hand, particularly a multi-finger robot hand. Thus, a link type continuously variable transmission configured to obtain a large reduction ratio is provided.

A link type continuously variable transmission according to the present invention is configured to be pivotally attached at a first pivot point to one end side of the base link member and the base link member, and the link length can be continuously changed. The input link member, the output link member pivotally attached to the other end side of the base link member at the second pivot point, and the input link member and the output link member so as to face the base link member An intermediate link member is provided. In such a link-type continuously variable transmission, input torque t _in input to rotate the input link member about a first pivot point rotating the output link member about the second pivot point is converted as an output torque t _out to be dynamic, the relationship between the input torque t _in the output torque t _out it is characterized by expressed by the following equation.
t _out = (L _out / L _in ) t _in
However, L _in is the length when the perpendicular is drawn from the first pivot point to the straight line connecting the two pivot points of the intermediate link member, and L _out is the intermediate link from the second pivot point. This is the length when a perpendicular is drawn with respect to a straight line connecting both pivot points of the member.

  In a preferred embodiment of the present invention, the input link member includes first and second link elements pivotally connected to each other with a pivot shaft, and an outer end side of the first link element is a first link element. Pivoted to the base link member at the pivot point, the outer end side of the second link element is pivoted to the corresponding end side of the intermediate link member, and changing the angle between the first and second link elements, The link length of the input link member is continuously changed.

  Further, according to one aspect of the present invention, the link type continuously variable transmission can be configured as a load sensitive type. That is, when the output link member receives a load, the first and second link elements are responsive to the load so that the first and second link elements are pivoted to reduce the angle therebetween. Elastic means are incorporated. In a preferred embodiment of such a link-type load-sensitive continuously variable transmission, the elastic means comprises a torsion spring mounted on the pivot shaft of the first and second link elements, and the two arms of the torsion spring A portion is locked to each of the first and second link elements.

  Furthermore, in another aspect of the present invention, the first link element is pivotally connected to the pivot shaft, and the second link element is fixed on the pivot shaft. The angle between the first and second link elements is variable. Thus, in such a link type continuously variable transmission, the reduction ratio can be arbitrarily changed by rotating the pivot shaft.

  Next, a first embodiment of a link type continuously variable transmission according to the present invention will be described with reference to FIG. 1 of the accompanying drawings.

  As shown in FIG. 1, the link type continuously variable transmission according to the present invention includes a base link member 10, which is held by a suitable support structure S. The link type continuously variable transmission also includes an input link member 12 pivotally attached to one end side of the base link member 10 at a first pivot point, and a second pivot point attached to the other end side of the base link member 10. An output link member 14 pivotally attached at a point and an input link member 12 and an intermediate link member 16 pivotally attached to the output link member 14 so as to face the base link member 10 are provided.

  In this embodiment, the input link member includes two link elements 12A and 12B, and these link elements 12A and 12B are pivotally connected to each other by a pivot shaft 18 on one end side. A pivot shaft 20 is fixed to the other end side, that is, the outer end side of the link element 12A, and one end side of the base link member 10 is pivotally connected to the pivot shaft 20. That is, the first pivot point described above, that is, the pivot point of the input link member 12 with respect to one end side of the base link member 10 is defined as one point on the central axis of the pivot shaft 20. On the other hand, the other end side, that is, the outer end side of the link element 12B is pivotally connected to the corresponding end side of the intermediate link member 16 by the pivot shaft 22.

  In this embodiment, a torsion spring 24 is attached to the pivot shaft 18 that pivotally attaches the link elements 12A and 12B to each other. One arm of the torsion spring 24 is locked by a protruding piece 26A extending from the side of the link element 12A, and the other arm is locked by a protruding piece 26B extending from the side of the link element 12B. The input link member 12 is maintained in the initial state as shown in FIG. 1 by the torsion spring 24, and at this time, the distance between the pivot shafts 20 and 22 is maximized.

  A protrusion 28 is fixed to the link element 12A of the input link member 12 on the side close to the end on the pivot shaft 20 side, and this protrusion 28 functions as a stopper piece for the link element 12B. That is, when the link element 12B is pivoted around the pivot shaft 18 in the clockwise direction (FIG. 1), the protrusion, that is, the stopper piece 28 comes into contact with the link element 12B.

  One end portion of the output link member 14 is pivotally connected to the other end side of the base link member 10 by a pivot shaft 30. That is, the second pivot point described above, that is, the pivot point of the output link member 14 with respect to the other end side of the base link member 10 is defined as one point on the central axis of the pivot shaft 30. On the other hand, the other end portion of the output link member 14 is pivotally connected to the corresponding end portion side of the intermediate link member 16 by a pivot shaft 32.

  Referring to FIG. 2, a physical model of the link type continuously variable transmission described above is shown. In the figure, the same reference numerals are used for the same components as those shown in FIG.

In FIG. 2, l _fix indicates the link length of the base link member 10. l _A and l _B indicate the respective link lengths of the link elements 12A and 12B of the input link member 12, and the link lengths l _A and l _B determine the actual link length l _vir of the input link member 12, and the link The length l _vir varies depending on the angle formed between the link elements 12A and 12B. l _out indicates the link length of the output link member 14, and l _M indicates the link length of the intermediate link member 16. In addition, L _in is a length when a perpendicular is lowered with respect to a straight line connecting between the pivot points of the intermediate link member 16 from the center of the pivot shaft 20 (that is, the first pivot point described above), L _out is the length when a perpendicular is drawn from the pivot shaft 30 (that is, the above-described second pivot point) to a straight line connecting the pivot points of the intermediate link member 16.

When a rotational driving force is transmitted to the pivot shaft 20 from, for example, an electric motor (not shown) through an appropriate speed reduction system, and the link element 12A of the input link member 12 is driven to rotate counterclockwise, the output link member 14 Are also driven to rotate counterclockwise around the pivot shaft 30. At this time, the torque and angular velocity of the link element 12A are defined as input torque and input angular velocity, respectively, and the torque and angular velocity of the output link member 14 are defined as output torque and output angular velocity, respectively. Is done. In FIG. 2, each of the input torque and the input angular rate is indicated by t _in and w _in, also each of the output torque and the output angular velocity indicated by t _out and w _out.

Further, in FIG. 2, an angle formed by a line segment extending outward from the center of the pivot shaft 20 along a line segment between the centers of the pivot shafts 20 and 30 and a line segment between the centers of the pivot shafts 20 and 22 is defined. represented by q _vir, angle between the line segment between the centers of the line segments and the pivot shaft 30 and 32 between the center of the pivot shaft 20 and 30 is represented by q _out. Of course, when the input link member 12 is rotated around the pivot shaft 20, the angle q _vir changes, and the angle q _out changes accordingly.

Here, assuming that the actual link length l _vir of the input link member 12 is fixed, that is, assuming that the input link member 12 is replaced by a single link member having the link length l _vir , link-type continuously variable transmission shown in FIG. 2 is four bar linkage, the relationship between input torque t _in the output torque t _out this time is expressed by the following equation.
t _out = (L _out / L _in ) t _in

By the way, in the link type continuously variable transmission according to the present invention, the effective link length l _vir of the input link member 12 is variable due to the _pivotability of the two link elements 12A and 12B. The parameter L _in also varies with the change of the link length l _vir . Thus, the link mechanism shown in FIG. 1 has a function as a link type continuously variable transmission.

The characteristics of such a link type continuously variable transmission were obtained by simulation calculation. That is, in the simulation calculation, a link member corresponding to the base link member 10 is l _fix = 47 [mm], and a link member corresponding to the output link member 14 is l _out = 9 [mm]. As the link member corresponding to the intermediate link member 16, a link member having l _M = 50 [mm] was used. In addition, six types of single input link members (l _vir = 5, 8, 11, 14, 17, 20 [mm]) having different lengths were used as corresponding to the input link member 12. In short, for the former three link members (l _fix = 47 [mm], l _out = 9 [mm], l _M = 50 [mm]), six types of single input link members (l _vir = 5, 8, 11, 14, 17, 20 [mm]) are incorporated in order, and simulation calculation of torque ratio (t _out / t _in ) and angular velocity ratio (w _out / w _in ) is performed for each four-bar linkage mechanism It was.

The calculation results of the torque ratio (t _out / t _in ) and the measurement results of the angular velocity ratio (w _out / w _in ) are shown in the graphs of FIGS. 3 and 4, respectively. As is clear from both graphs, the shorter the length of the single input link member (l _vir = 5, 8, 11, 14, 17, 20 [mm]), the torque ratio (t _out / t _in ) As a whole, the angular velocity ratio (w _out / w _in ) decreases as a whole. In the link mechanism shown in FIG. 1, the change in the actual link length l _vir of the input link member 12 is continuous, so that the link mechanism functions as a continuously variable transmission.

  The link type continuously variable transmission shown in FIG. 1 is configured as a load-sensitive continuously variable transmission that can be advantageously applied to a multi-fingered robot hand. When combined, the gear shifting function is exhibited. Referring to FIGS. 5 to 7, an example of operation when the link type load-sensitive continuously variable transmission shown in FIG. 1 is applied to a multi-fingered robot hand is illustrated step by step. 5 to 7, reference numeral 34 indicates a fingertip member fixed to the output link 14, and reference numeral 36 indicates an object to be grasped. 5 to 7, the torsion spring 24 is omitted for simplification of illustration.

When the link element 12A of the input link member 12 is driven to rotate while the fingertip member 34 is not subjected to any load, the effective link length l _vir of the input link member 12 is the maximum for the torsion spring 24. The angular velocity ratio (w _out / w _in ) is also maximized, and the movement of the fingertip member 34 is the fastest.

As shown in FIG. 5, when the link element 12A of the input link member 12 is driven to rotate counterclockwise and the fingertip member 34 abuts on the grasped object 36, that is, when the fingertip member 34 is sensitive to a load, the output is performed. The movement of the link member 14 is stopped. As a result, as is apparent from FIGS. 5 and 6, the link elements 12A and 12B of the input link member 12 are pivoted so as to approach each other against the spring elastic force of the torsion spring 24, thereby the input link. The link length l _vir of the member 12 is gradually shortened to increase the output torque t _out , and accordingly, the gripping force F exerted on the gripping object 36 by the fingertip member 34 is also gradually increased.

When the link element 12A of the input link member 12 is further rotated in the counterclockwise direction and the link element 12B is brought into contact with the stopper piece 28 on the link element 12A, the link length l _vir of the input link member 12 is becomes minimal, as shown in FIG. 7, this time torque ratio (t _out / t _in) is the largest, the gripping force F becomes the maximum for the input torque t _in.

For example, the maximum value of the actual link length l _vir of the input link member 12 is 20 [mm], and the angle q _out when the fingertip member 34 abuts the grasped object 36 is 100 [deg]. Then, in the operation shown in FIGS. 5 to 7, the torque ratio (t _out / t _in ) increases from point A to point B on the graph of FIG. 3, and the angular velocity ratio (w _out / w _in ) It decreases from point A on point 4 along point B. When a gripping force larger than the maximum gripping force F shown in FIG. 7 is required, after the link element 12B is brought into contact with the stopper piece 28 on the link element 12A, the link element 12A it is sufficient to increase the input torque t _in for.

In the above mentioned link-type continuously variable transmission, to the input torque t _in, verified by measurement experiment about the power obtained from the output link member 14. For this measurement experiment, a measurement rod 38 as shown by a two-dot chain line in FIG. 5 is connected to the output link member 14, and the measurement on the measurement rod 38 separated from the center of the pivot shaft 30 by 45 [mm]. Measurements were made of the force available at the site. For this measurement, a load measuring device (MODEL-9810) manufactured by Aiko Engineering Co., Ltd. is used, and the measurement point on the measuring rod 38 (45 [mm] from the center of the pivot shaft 30) is the measurement detector of the load measuring device. At this time, the angle q _out was 82 [deg]. The angle between the two link elements 12A and 12B of the input link member 12 is 135 [deg]. At this time, the torsion spring 24 has a natural length, and its spring constant is [0.196 Nmm / deg].

The measurement results are indicated by black circle plots in the graph of FIG. Link length l _vir of the input link member 12 as the input torque t _in increases becomes short, link length l _vir of the input link member 12 when the input torque t _in about 0.07 [Nm] is minimized. That is, the link length l _vir of the input link member 12 to the input torque t _in reaches about 0.07 [Nm] are performed continuously stepless to change, the gripping force F is increasing rapidly Can be read. Moreover, when further increasing the input torque t _in, link element 12B is supported by the stopper 28, can not be rotated relative to the link element 12A, the link length l _vir of the input link member 12 is kept to a minimum The gripping force F is output at the maximum speed ratio in the manner of gripping the fingertip member 34. In the graph of FIG. 8, the broken line BL shows the transition of the maximum gear ratio when the link length l _vir is minimized.

For comparison, the link elements 12A and 12B of the input link member 12 are intentionally fixed so that they cannot pivot with respect to each other, and the link length l _vir (L _in = 14.5 [mm]) is constant. The same measurement is performed, and the measurement result is shown by a black square plot in the graph of FIG. As is clear from the comparative example, when the link length of the input link member 12 is constant, a large force cannot be output.

  As is apparent from the above description, when the link type continuously variable transmission according to the present invention is configured as a load-sensitive type, the reduction ratio is infinite depending on how the fingertip member 34 is gripped. In particular, it can be advantageously applied to a multi-fingered robot hand. This is because, as already described, until the fingertip member 34 captures the grasped object 36, the fingertip member 34 moves quickly, and as soon as the grasped object 36 is once captured by the fingertip member 34, a large grasping force is applied. This is because it extends from the member 34 to the grasped object 36.

  Referring to FIG. 9, there is shown a second embodiment of the link type continuously variable transmission according to the present invention. In the second embodiment, the link type continuously variable transmission is not configured as a load-sensitive type, and can be arbitrarily set with a reduction ratio.

  As shown in FIG. 9, in the second embodiment, the torsion spring 24 and the stopper piece 28 are not used. One end of each of the link elements 12A and 12B of the input link member 12 is pivotally connected to the pivot shaft 18 in the first embodiment described above, but in the second embodiment, the one end of the link element 12A. Only one end is pivotally connected to the pivot shaft 18 so that one end of the link element 12B is secured onto the pivot shaft 18. A toothed pulley 40 is fixed on the pivot shaft 18, and a toothed endless driving belt 42 is attached to the toothed pulley 40.

In the second embodiment, the link element 12B is rotated about the pivot shaft 18 by appropriately driving the toothed endless drive belt 42, whereby the distance between the centers of the pivot shafts 20 and 22, ie, the input. The link length l _vir of the link member 12 can be changed. In short, the reduction ratio of the link type continuously variable transmission can be arbitrarily selected by driving the toothed endless drive belt 42.

In the first and second embodiments described above, in order to make the link length l _vir of the input link member 12 variable, the input link member 12 connects the two link elements 12A and 12B to each other by the pivot shaft 18. However, it is also possible to form the input link member 12 by other means for making the distance l _vir between the pivot shafts 20 and 22 variable. For example, by providing a ball screw / nut mechanism or a pinion / rack mechanism between the pivot shafts 20 and 22 via a swivel joint or the like as appropriate, an input link mechanism with a variable link length l _vir can be configured.

1 is an elevational view showing a first embodiment of a link type continuously variable transmission according to the present invention. It is a conceptual diagram which shows the physical model of the link type continuously variable transmission shown in FIG. 2 is a graph for explaining how the torque ratio of output torque to input torque changes due to a change in link length of an input link member in the link type continuously variable transmission shown in FIG. 1. 2 is a graph for explaining how the angular velocity ratio of the output angular velocity to the input angular velocity changes due to the change in the link length of the input link member in the link type continuously variable transmission shown in FIG. 1. It is explanatory drawing which shows the typical step of the operation example at the time of applying the link type load-sensitive continuously variable transmission shown in FIG. 1 in a multi-fingered robot hand. FIG. 6 is an explanatory diagram showing another representative stage of the operation example of FIG. 5. FIG. 6 is an explanatory diagram showing still another representative stage of the operation example of FIG. 5. 2 is a graph showing a measurement result of force obtained from an output link member with respect to input torque in the link type continuously variable transmission shown in FIG. 1. FIG. 6 is an elevation view showing a second embodiment of the link type continuously variable transmission according to the present invention.

Explanation of symbols

10: Base link member 12: Input link member 12A: Link element 12B: Link element 14: Output link member 16: Intermediate link member 18: Pivot shaft 20: Pivot shaft 22: Pivot shaft 24: Torsion spring 26A: Protruding piece 26B: Protruding piece 28: Protruding body (stopper piece)
30: Pivot shaft 32: Pivot shaft 34: Fingertip member 36: Grasping object 38: Measuring rod 40: Toothed pulley 42: Toothed endless driving belt S: Support structure

Claims (5)

A base link member, an input link member pivotally attached to one end side of the base link member at a first pivot point, and configured to continuously change the link length; An output link member pivotally attached to the end at a second pivot point; and an intermediate link member pivotally attached to the input link member and the output link member so as to face the base link member; output torque t _out rotating the output link member about the input torque t _in input the input link member about the first pivot point so as to rotate the said second articulation point In the link type continuously variable transmission converted as
Link-type continuously variable transmission relationship between said input torque t _in and the output torque t _out, characterized in that the expressed by the following equation.
t _out = (L _out / L _in ) t _in
However,
L _in is the length when a perpendicular is drawn from the first pivot point to a straight line connecting the pivot points of the intermediate link member;
L _out is the length when a perpendicular is drawn from the second pivot point to a straight line connecting the pivot points of the intermediate link member.   2. The link type continuously variable transmission according to claim 1, wherein the input link member includes first and second link elements pivotably connected to a pivot shaft, and an outer end of the first link element. The first link point is pivotally attached to the base link member at the first pivot point, the outer end side of the second link element is pivotally attached to the corresponding end side of the intermediate link member, and the first and second link elements A link type continuously variable transmission, wherein the link length of the input link member is continuously changed by changing the angle between the two.   3. The link type continuously variable transmission according to claim 2, wherein when the output link member receives a load, the first and second link elements pivot to reduce the angle therebetween in response to the load. A link type continuously variable transmission, characterized in that elastic means is incorporated in the first and second link elements.   4. The link type continuously variable transmission according to claim 3, wherein the elastic means comprises a torsion spring mounted on a pivot shaft of the first and second link elements, and two arm portions of the torsion spring are the first and second link portions. A link type continuously variable transmission that is locked to each of the first and second link elements. 3. The link type continuously variable transmission according to claim 2, wherein the first link element is pivotally connected to the pivot shaft, and the second link element is fixed on the pivot shaft. A link type continuously variable transmission characterized in that the angle between the first and second link elements is made variable by the rotational drive of.

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