JP4660770B2 - 3-DOF active rotary joint - Google Patents

Description

  The present invention relates to a three-degree-of-freedom active rotary joint that enables arbitrary rotational relative motion in a direction of three degrees of freedom between two links.

  In recent years, robot technology has been applied to various fields, for example, the medical field. In robots, it is necessary to perform functions similar to the functions of human hands, feet, heads, etc., and joints that can be actively rotated with three degrees of freedom are required.

  Generally, when an object can be rotated around three axes orthogonal to each other at the same time, the object has three degrees of freedom of rotation. For example, as shown in FIG. 11, the human neck can move back and forth and from side to side and rotate left and right, and has three degrees of freedom.

  When an arbitrary rotational relative motion in the direction of three degrees of freedom is possible between two links by a joint that connects two links, this joint is referred to as a three-degree-of-freedom rotational joint. In particular, an object that can be actively operated by an actuator is called an active joint, and an object that cannot generate a driving force is called a passive joint.

  Examples of the three-degree-of-freedom rotary joint include a ball joint that can be passively rotated with three degrees of freedom (see Patent Document 1) and a parallel mechanism that can be actively rotated with three degrees of freedom. As shown in FIG. 12, the parallel mechanism refers to a mechanism in which the base to the end plate, which is the final output, are connected in parallel by a plurality of links. For example, Stewart Platform type (FIG. 12A), Hexa type (FIG. 12B), a linear motion fixed type (FIG. 12C), and the like are known.

JP-A-8-240442

  However, the parallel mechanism has advantages such as high rigidity, but it has been pointed out that it cannot perform uniform movement in the direction of each degree of freedom and the structure is complicated.

  The present invention has been made in view of the above points, and is capable of uniform rotational movement in an arbitrary direction composed of directions of each degree of freedom, and has a simple structure close to a ball joint. An object is to provide an active rotary joint.

The three-degree-of-freedom active rotary joint according to the present invention is a three-degree-of-freedom active rotary joint provided between a pair of links, and is for the X-axis arranged orthogonal to each other so that the output axis is directed to the origin of the three orthogonal axes The rotary actuator for the Y axis and the Z axis, the rotating body coupled to the output shaft of the rotary actuator for the X axis, the Y axis, and the Z axis, and the rotary actuator for the X axis. A movable support that restricts rotation around the axis and supports rotation around one of the other two orthogonal axes, and a rotation actuator for the Y axis rotate around its own axis. In addition to restricting the rotation around the axis of the movable support that supports the rotation to one of the other two orthogonal axes and the rotation actuator for the Z axis Other orthogonal A movable support that supports rotation around one axis so as to allow rotation, and a support that supports the movable support so as to allow rotation around the other two orthogonal axes. And a fourth rotary actuator provided in any one of the X-axis, Y-axis, and Z-axis rotary actuators, the output shaft of which is directed in the direction opposite to the output shaft of the rotary actuator And one of the pair of links is fixed to the output shaft of the fourth rotary actuator, and the other link is fixed to the support.
Another feature of the three-degree-of-freedom active rotary joint according to the present invention is that the rotary body is a rotary sphere, and further, a rotary sphere receiver that supports the rotary sphere so as to be rotatable in an arbitrary direction. And the rotary ball receiver is supported by the support.
In addition, another feature of the three-degree-of-freedom active rotary joint according to the present invention is that the X-axis, Y-axis, and Z-axis rotary actuators have a hollow axis directed at the origin of three orthogonal axes. The X-axis, Y-axis, and Z-axis hollow shaft rotary actuators arranged orthogonally to each other, and the X-axis and Y-axis inserts inserted into the hollow shafts of the respective hollow-axis rotary actuators, And the output shaft of any one of the hollow-axis rotary actuators for the X-axis, Y-axis, and Z-axis. The hollow shaft rotary actuator also serves as the fourth rotary actuator by fixing the one link to the output shaft protruding from the rear end of the rotary actuator.

  According to the present invention, if the rotary actuators for X-axis, Y-axis, and Z-axis are simultaneously and independently rotated, uniform rotational motion in any direction consisting of directions of degrees of freedom is possible. Become. In addition, a three-degree-of-freedom active rotary joint having a structure close to a ball joint and having a simple structure can be provided.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a perspective view showing a three-degree-of-freedom active rotary joint according to the first embodiment. 2 is a partial sectional view as seen from the x direction in FIG. 1, FIG. 3 is a partial sectional view as seen from the y direction in FIG. 1, and FIG. 4 is a partial sectional view as seen from the z direction in FIG. FIG. 5 is a partial sectional view taken along line VV in FIG.

  The three-degree-of-freedom active rotary joint of the present embodiment is provided between a pair of links 60a and 60b, and includes a rotary ball 10, a hollow-axis rotary motor 20x for X-axis, Y-axis, and Z-axis. 20y, 20z, movable support members 30x, 30y, 30z for supporting the hollow shaft rotary motors 20x, 20y, 20z, respectively, a rotating ball receiver 40 for supporting the rotating ball 10 to be rotatable in an arbitrary direction, a movable support member 30x, 30y and 30z and the support body 50 etc. which support the rotation ball receiver 40 are comprised.

  The X-axis, Y-axis, and Z-axis hollow shaft rotary motors 20x, 20y, and 20z are arranged orthogonally to each other so that the axis of the hollow shaft is directed to the origin of three orthogonal axes. The output shafts 21x, 21y, and 21z are inserted into the main body. In the illustrated example, in the Z-axis hollow shaft rotary motor 20z, the output shaft 21z penetrates the hollow shaft, and the output shaft 21z protrudes not only from the front end but also from the rear end.

  As these hollow shaft rotary motors 20x, 20y, and 20z, for example, a geared motor in which a hollow shaft and a reduction gear are combined together and an encoder that measures the rotation angle and rotation speed thereof are used. The X-axis, Y-axis, and Z-axis hollow shaft rotary motors 20x, 20y, and 20z correspond to the X-axis, Y-axis, and Z-axis hollow shaft rotary actuators referred to in the present invention, respectively. Is.

  As shown in FIG. 6, the rotating sphere 10 is arranged so that the center thereof coincides with the origin of the three orthogonal axes, and as shown in FIG. 7, the rotating sphere 10 has through holes 11 x arranged orthogonal to each other. 11y and 11z are formed.

  The output shafts 21x, 21y, and 21z protruding from the front ends of the X-axis, Y-axis, and Z-axis hollow shaft rotary motors 20x, 20y, and 20z are inserted into the through holes 11x, 11y, and 11z, respectively. Coupled to the rotating sphere 10. In this case, the output shaft 21x of the X-axis hollow shaft rotary motor 20x and the output shaft 21y of the Y-axis hollow shaft rotary motor 20y are extended to the center of the rotating ball 10. Thus, the output shaft 21 z of the Z-axis hollow shaft rotary motor 20 z extends beyond the center of the rotating sphere 10 and penetrates the rotating sphere 10. This is because the link 60a is fixed to the output shaft 21z as described later, in other words, since the output shaft 21z extends outside the joint, it is longer than the other output shafts 21x and 21y. That is, the moment transmitted to the rotating sphere 10 by the output shaft 21z is also larger than the moment by the other output shafts 21x and 21y. Therefore, in order to make the coupling between the output shaft 21z and the rotating sphere 10 solid and to transmit the moment from the output shaft 21z to the rotating sphere 10 well, the output shaft 21z is passed through the rotating sphere 10 and The contact area is increased. Although not specifically shown, a plurality of key grooves are cut on the output shafts 21x, 21y, and 21z, or pins are protruded in the radial direction, and engaged with the through holes 11x, 11y, and 11z. By doing so, the rotational force of each output shaft 21x, 21y, 21z is transmitted to the rotating body 10.

  As shown in FIGS. 1 and 5, the support 50 has a partial spherical shape that is concentric with the rotating sphere 10, and has support end portions 50 x, 50 y, and 50 z located on three orthogonal axes.

  As shown in FIG. 1, the rotating ball receiver 40 has a hollow spherical shape that is concentric with the rotating ball 10, and functions as a spherical plain bearing that supports the rotating ball 10 to be rotatable in an arbitrary direction. In the rotating ball receiver 40, a substantially quadrangular opening is formed around each of the output shafts 21x, 21y, and 21z by a frame 41 corresponding to the meridian on the earth and a frame 42 corresponding to the latitude on the earth. As shown in FIG. 5, the rotating ball receiver 40 is supported by a support body 50 via a columnar support portion 53.

  The movable supports 30x, 30y, and 30z will be described by paying attention to the movable support 30x that supports the X-axis hollow shaft rotary motor 20x. The movable support 30 x is formed of a hollow prism member that is concentrically curved with the great circle of the rotating sphere 10. Specifically, as shown in FIG. 8D, the hollow portion 31 of the movable support 30x has a trapezoidal shape that is wide on the motor 20x side and narrow on the rotating sphere 10 side in a cross section orthogonal to the longitudinal direction. It has become. Further, long holes 32 and 33 having a width through which the output shaft 21x is inserted are formed in the longitudinal direction on the surface of the movable support 30x on the motor 20x side and the surface on the rotating sphere 10 side.

  A slider 34 is incorporated in the hollow portion 31 of the movable support 30x. The slider 34 has a substantially rectangular parallelepiped shape having an outer cylindrical surface 34a on the motor 20x side, an inner cylindrical surface 34b on the rotating sphere 10 side, two fan-shaped surfaces 34c and 34c, and two rectangular surfaces 34d and 34d. The outer cylindrical surface 34a and the inner cylindrical surface 34b are concentric with the movable support 30x, in other words, are concentrically curved with the great circle of the rotating sphere 10.

  Rollers 35 are disposed on the respective cylindrical surfaces 34a and 34b and the sector surfaces 34c and 34c. Two rollers 35 are arranged in the longitudinal direction on each of the surfaces 34 a, 34 b, 34 c and assembled so as to be half-immersed in the slider 34. When the slider 34 is incorporated in the hollow portion 31, the dimensions are designed so that there is no gap between each roller 35 and each inner surface of the hollow portion 31, so that the slider 34 does not rattle in the hollow portion 31. . As a result, the slider 34 can slide in the longitudinal direction in the movable support 30x with low friction while the roller 35 rolls on each inner surface of the hollow portion 31 while maintaining a certain distance from the rotating ball 10.

  The front end of the X-axis hollow shaft rotary motor 20 x is fixed to the outer cylindrical surface 34 a of the slider 34 via a pair of support plates 36. In this case, the output shaft 21 x protruding from the front end of the X-axis hollow shaft rotary motor 20 x passes through the slider 34 and is coupled to the rotating sphere 10.

  With the configuration described above, the X-axis hollow shaft rotary motor 20x is restricted from rotating around its own axis because the slider 34 does not rattle within the hollow portion 31 of the movable support 30x. Further, since the slider 34 can reciprocate along the movable support 30x, rotation around the Y axis among the other two orthogonal axes is allowed.

  As shown in FIG. 5, the movable support body 30 x configured as described above is pivotally supported by a rotation shaft 51 with respect to a support end portion 50 z located on the Z axis in the support body 50. The rotating shaft 51 is fixed to the end portion of the movable support 30x, and is rotatably supported via two bearings 52 built in the supporting end portion 50z. By arranging the two bearings 52 in the axial direction of the rotating shaft 51 in this way, even when an external force is applied to incline the rotating shaft 51, the two bearings 52 are supported and the inclination of the rotating shaft 51 is reduced. Can be prevented.

  With the configuration described above, the movable support 30x, in other words, the X-axis hollow shaft rotary motor 20x is allowed to rotate around the Z-axis among the other two orthogonal axes.

  Here, the description has been made focusing on the movable support 30x that supports the X-axis hollow shaft rotary motor 20x. However, the movable support 30y that supports the Y-axis and Z-axis hollow shaft rotary motors 20y and 20z. , 30z.

  In the three-degree-of-freedom active rotary joint of the present embodiment described above, as shown in FIG. 1, one link 60a of the pair of links 60a and 60b is from the rear end of the Z-axis hollow shaft rotary motor 20z. The projecting output shaft 21z is coaxially fixed, and the other link 60b is fixed to the outer surface side of the support end 50z of the support 50.

  According to the three-degree-of-freedom active rotary joint of the present embodiment, each of the X-axis, Y-axis, and Z-axis hollow shaft rotary motors 20x, 20y, and 20z can be rotated simultaneously independently. A uniform rotational movement in an arbitrary direction consisting of degrees is possible. In addition, a three-degree-of-freedom active rotary joint having a structure close to a ball joint and having a simple structure can be provided.

(Second Embodiment)
As a second embodiment, referring to FIG. 9, another configuration example of a slider incorporated in the movable supports 30x, 30y, and 30z is shown. In FIG. 9, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The shape of the slider 134 itself is the same as the slider 34 shown in FIG. 8, the outer cylindrical surface 134a on the motor 20x side, the inner cylindrical surface 134b on the rotating sphere 10 side, the two fan-shaped surfaces 134c and 134c, the two rectangular surfaces 134d, It has a substantially rectangular parallelepiped shape having 134d.

  A bearing housing recess 131 is formed at each corner of the sectoral surfaces 134c and 134c and the rectangular surfaces 134d and 134d. In the bearing housing recess 131, the bearing 133 is pivotally supported by shafts supported by the outer cylindrical surface 134a and the inner cylindrical surface 134b. When the slider 134 is incorporated in the hollow portion 31, the dimensions are designed so that there is no gap between the bearing 133 and the inner surface of the hollow portion 31, so that the slider 134 does not rattle in the hollow portion 31. .

  Moreover, the recessed part 135 opened to the outer cylindrical surface 134a and the inner cylindrical surface 134b is formed in the center of the fan-shaped surfaces 134c and 134c. In the recess 135, the bearing 136 is pivotally supported by a shaft protruding from the bottom of the recess 135. When the slider 134 is incorporated in the hollow portion 31, the dimensions are designed so that there is no gap between the bearing 136 and the inner surface of the hollow portion 31 on the motor 20 x side and the inner surface on the rotating sphere 10 side. It is designed not to rattle.

  As a result, the slider 134 slides in the longitudinal direction of the movable support 30x with low friction while the bearings 133 and 136 roll on the inner surfaces of the hollow portion 31 while maintaining a certain distance from the rotating ball 10. sell.

(Third embodiment)
FIG. 10 is a perspective view showing a three-degree-of-freedom active rotary joint according to the third embodiment. In FIG. 10, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the first embodiment, the front ends of the X-axis, Y-axis, and Z-axis hollow shaft rotary motors 20x, 20y, and 20z are fixed to the movable supports 30x, 30y, and 30z (the slider 34). However, in the present embodiment, as shown in FIG. 9, the rear ends of the X-axis, Y-axis, and Z-axis hollow shaft rotary motors 20x, 20y, and 20z are connected to the movable supports 30x, 30y, It is fixed to 30z (the slider 34).

  In this way, when the rear ends of the X-axis, Y-axis, and Z-axis hollow shaft rotary motors 20x, 20y, and 20z are fixed to the movable supports 30x, 30y, and 30z (the slider 34), the X-axis is used. In the movable support 34 that supports the Y-axis hollow shaft rotary motors 20x and 20y, a through hole for allowing the slider 34 to pass through the output shaft 21x becomes unnecessary. However, in the movable support 34 that supports the Z-axis hollow shaft rotary mode 20z, the output shaft 21z that protrudes from the rear end of the Z-axis hollow shaft rotary motor 20z passes through the slider 34 and is coaxial. The link 60a is fixed to the frame.

  In each of the above embodiments, the hollow shaft rotary motor has been described as an example, but a normal motor having an output shaft may be used. In this case, the Z-axis motor and the fourth motor may be arranged in series and connected so that the output shafts are directed in opposite directions. Then, the rotation of the output shaft of the Z-axis motor and the output shaft of the fourth motor are made the same rotation, and the other two motors (X-axis motor and Y-axis motor) If the rotations are independently and simultaneously, uniform rotation in any direction consisting of directions of degrees of freedom becomes possible. In other words, the fourth rotary actuator referred to in the present invention may be separate from the X-axis, Y-axis, and Z-axis rotary actuators. The actuator may also serve as the fourth rotary actuator.

  As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention. For example, in each of the above embodiments, the rotating sphere 10 is used as the rotating body referred to in the present invention and is rotatably supported by the rotating sphere receiver 40. However, the rotating sphere 10 is supported by the output shafts 21x, 21y, and 21z. From the viewpoint of the kinematic principle, it is not necessary to make the rotating body other than a spherical shape (for example, a hexahedron) or to support the rotating body rotatably by the rotating ball receiver 40. However, using the rotating sphere 10 and supporting it with the rotating sphere receiver 40 provides high rigidity, and can reduce the influence of the assembly error and dimensional error of each part and perform precise movement.

It is a perspective view which shows the 3-degree-of-freedom active rotary joint of 1st Embodiment. FIG. 2 is a partial cross-sectional view seen from the x direction in FIG. 1. FIG. 2 is a partial cross-sectional view seen from the y direction in FIG. 1. FIG. 2 is a partial cross-sectional view seen from the z direction in FIG. 1. FIG. 5 is a partial cross-sectional view taken along line VV in FIG. 2. It is a figure which shows the relationship between a rotating sphere and an X-axis, a Y-axis, and a Z-axis. It is a figure for demonstrating a rotation sphere, (a) is sectional drawing which follows the AA line of (b), (b) is a top view. It is a figure for demonstrating a movable support body, (a) is a side view, (b) is a partial cross section figure along the AA line of (a), (c) is a part in alignment with the BB line of (a). Sectional drawing and (d) are partial sectional views in alignment with CC line of (a). It is a figure for demonstrating another movable support body, (a) is a side view, (b) is a partial sectional view which follows the AA line of (a), (c) is along the BB line of (a). Partial sectional drawing, (d) is a partial sectional view along CC line of (a). It is a perspective view which shows the 3 degrees of freedom active rotation joint of 2nd Embodiment. It is a figure for demonstrating that a human neck has 3 degrees of freedom. It is a figure which shows the example of the parallel mechanism known as a 3-degree-of-freedom active rotary joint.

Explanation of symbols

10 Rotating sphere 20x Hollow shaft rotary motor for X axis 20y Hollow shaft rotary motor for Y axis 20z Hollow shaft rotary motor for Z axis 21x, 21y, 21z Output shaft 30x, 30y, 30z Movable support 40 Rotation Ball receiver 50 Support 60a, 60b Link

Claims (5)

A 3-DOF active rotary joint provided between a pair of links,
Rotary actuators for X-axis, Y-axis, and Z-axis that are arranged orthogonally to each other so that the output axis is directed to the origin of three orthogonal axes;
A rotating body coupled to the output shaft of the rotary actuator for the X axis, the Y axis, and the Z axis;
A movable support for supporting the rotation actuator for the X axis so as to restrict rotation about the axis of the X axis and to allow rotation to one of the other two orthogonal axes;
A movable support for supporting the rotation actuator for the Y axis so as to restrict rotation about its own axis and to allow rotation to one of the other two orthogonal axes;
A movable support for supporting the rotation actuator for the Z axis so as to restrict rotation about its own axis and to allow rotation to one of the other two orthogonal axes;
A support that supports the movable support so as to allow rotation to the other of the other two orthogonal axes;
A fourth rotary actuator provided on any one of the X-axis, Y-axis, and Z-axis rotary actuators, the output axis of which is directed in the direction opposite to the output axis of the rotary actuator; Prepared,
A three-degree-of-freedom active rotary joint, wherein one of the pair of links is fixed to an output shaft of the fourth rotary actuator, and the other link is fixed to the support.   The three-degree-of-freedom active rotary joint according to claim 1, wherein the rotary body is a rotary sphere.   The three-degree-of-freedom active rotary joint according to claim 2, further comprising a rotary ball receiver that supports the rotary ball so as to be rotatable in an arbitrary direction, and the rotary ball receiver is supported by the support.   The X-axis, Y-axis, and Z-axis rotary actuators are for the X-axis, Y-axis, and Z-axis that are arranged orthogonally to each other so that the axis of the hollow axis is directed to the origin of three orthogonal axes 2. A hollow shaft rotary actuator, and an output shaft for X axis, Y axis, and Z axis inserted into the hollow shaft of each of the hollow shaft rotary actuators. 4. The three-degree-of-freedom active rotary joint according to claim 1.   The output shaft is configured to pass through any one of the X-axis, Y-axis, and Z-axis hollow shaft rotary actuators, and the output projecting from the rear end of the rotary actuator The three-degree-of-freedom active rotary joint according to claim 4, wherein the hollow shaft rotary actuator also serves as the fourth rotary actuator by fixing the one link to the shaft.

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