JP2008068367A - Joint mechanism of robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint mechanism capable of respectively driving a plurality of joints by a single driving source. <P>SOLUTION: The first joint B, the second joint C and the third joint D tilt relative to a stator 2 while holding their relative postures in accordance with tilting of an output shaft member 5 when tilting the output shaft member 5 relative to the stator 2 by rotating a rotor 4. A second bevel gear 8 rotates around a shaft S1 of the second joint and the second joint C tilts relative to the first joint B as a first bevel gear 6 rotates in accordance with rotation of the output shaft member 5 when rotating the output shaft member 5 around its own shaft by rotating the rotor 4. Additionally, a sixth bevel gear 12 rotates around a shaft S2 of the third joint through a fourth bevel gear 10 and a fifth bevel gear 11 and the third joint D tilts relative to the second joint C due to rotation of a third bevel gear 9 in accordance with rotation of the first bevel gear 6 at this time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a joint mechanism of a robot, and more particularly to a joint mechanism having a plurality of joints and constituting fingers or the like of a robot hand.

  In recent years, various types of robot hands that move in a manner similar to human hands have been developed, and one finger of such a robot hand can be configured using a joint mechanism having a plurality of joints. This joint mechanism generally has a motor, an actuator, and the like for driving a joint to bend and stretch a finger as a drive source.

  For example, the joint mechanism of the robot hand disclosed in Patent Document 1 has a plurality of joints, and a dedicated motor for driving the joints is provided adjacent to each joint. By doing so, the joint corresponding to this motor is driven and the finger is bent and stretched.

Japanese Patent Laid-Open No. 11-156778

However, in the joint mechanism of Patent Document 1, since one joint is driven by one motor, it is necessary to provide a plurality of motors corresponding to each of the plurality of joints, resulting in a complicated configuration. It was.
The present invention has been made to solve such problems, and an object of the present invention is to provide a joint mechanism capable of driving a plurality of joints by one drive source.

  A robot joint mechanism according to the present invention includes a stator and a substantially spherical rotor that is disposed in contact with the stator and used as a first joint, and the rotor is rotated around a plurality of axes by vibrating the stator. The first degree joint formed in the axial direction of the output shaft member projecting from the surface of the rotor of the multi-degree-of-freedom actuator and the multi-degree-of-freedom actuator; The second joint, the converting means for driving the second joint by the rotational movement of the output shaft member around its axis and tilting the second joint relative to the first joint, and the rotational movement of the output shaft member around the axis thereof. And a holding means for holding the second joint so that the second joint does not rotate together with the output shaft member. The rotor of the multi-degree-of-freedom actuator is rotated to tilt the output shaft member with respect to the stator. The first joint and the second joint are tilted with respect to the stator while maintaining the relative posture of each other without driving the second joint, and the output shaft member is rotated about its axis via the conversion means. The second joint is driven to tilt the second joint relative to the first joint.

The conversion means includes a first bevel gear fixed to the tip of the output shaft member, and a second bevel gear fixed to the second joint on the shaft of the second joint and meshing with the first bevel gear. It can comprise so that.
The holding means includes a first holding member that holds the first node so that it can tilt with respect to the stator and does not rotate about its axis, and a second member that can tilt relative to the first node and its axis It can comprise so that it may have a 2nd holding member hold | maintained so that it may not rotate around.

The third to n-th nodes are sequentially connected to the tip of the second node through the third to n-th joints so that n ≧ 3, and interlocking means for sequentially transmitting the driving of the second joints to the third to n-th joints is provided. You can also.
The multi-degree-of-freedom actuator has a composite vibrator composed of a plurality of piezoelectric element plates stacked on each other, and the stator is vibrated by the composite vibrator to generate an elliptical or circular motion at the contact portion between the stator and the rotor. Thus, the rotor can be rotated around a plurality of axes.

  According to the present invention, it is possible to realize a joint mechanism that can drive a plurality of joints by one drive source.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view in which a part of the joint mechanism of the robot according to the embodiment of the present invention is broken. This joint mechanism constitutes, for example, one finger of a robot hand, and has one multi-degree-of-freedom actuator A as its drive source. In this multi-degree-of-freedom actuator A, the composite vibrator 3 is disposed between the base block 1 and the stator 2, and the spherical shape used as the first joint of the joint mechanism is provided in the recess provided in the stator 2. The rotor 4 is accommodated rotatably. The rotor 4 can be rotated around a plurality of axes by vibrating the stator 2.

  An output shaft member 5 extending linearly from the surface of the rotor 4 toward the radially outer side of the rotor 4 is fixed to the rotor 4, and the output shaft member 5 is rotated as the rotor 4 rotates. It is comprised so that it may move with. A first bevel gear 6 having the output shaft member 5 as a rotation shaft is fixed to the distal end of the output shaft member 5 in the extending direction. Here, two annular plates 7 are attached to the outer peripheral portion of the output shaft member 5 at intervals in the axial direction of the output shaft member 5, and the plates 7 and the output shaft member 5 are mutually connected. It is arranged so that it can rotate freely. A substantially cylindrical first node B is fixed to the outer peripheral portions of these two plates 7, and the two plates 7, a part of the output shaft member 5, and the first A bevel gear 6 is accommodated.

A substantially cylindrical second node C is connected to the tip of the first node B via an axis S1 of the second joint so as to be tiltable. Further, a substantially cylindrical third section D is connected to the tip of the second section C via an axis S2 of the third joint so as to be tiltable, and the tip of the third section D is formed in a hemispherical shape. ing.
The first bevel gear 6 positioned at the tip of the output shaft member 5 is meshed with a second bevel gear 8 fixed to the second joint C on the shaft S1 of the second joint. Further, the first bevel gear 6 is meshed with a third bevel gear 9 disposed so as to face the second bevel gear 8. The third bevel gear 9 is arranged so as to be able to rotate around the axis S1 of the second joint independently of each other. A fourth bevel gear 10 is meshed with the third bevel gear 9, and a fifth bevel gear 11 is integrally formed with the fourth bevel gear 10. The fifth bevel gear 11 is meshed with a sixth bevel gear 12 fixed to the base end of the third joint D on the third joint axis S2.

Here, the second bevel gear 8, the third bevel gear 9, the fourth bevel gear 10, and the fifth bevel gear 11 are accommodated in the second section C, and the second section The shafts of the fourth bevel gear 10 and the fifth bevel gear 11 are rotatably supported by a bearing 13 attached to the inner surface of C.
The sixth bevel gear 12 is housed inside the third node D.

Further, the first node B is connected to the stator 2 via the first holding member 14. The first holding member 14 holds the first node B so that it can tilt with respect to the stator 2 and does not rotate around its axis. The second node C is connected to the first node B through the second holding member 15. The second holding member 15 holds the second joint C so that it can tilt with respect to the first joint B and does not rotate about its axis, and is fixed to the second joint C. The state where the gear 8 meshes with the first bevel gear 6 and the third bevel gear 9 meshes with the first bevel gear 6 and the fourth bevel gear 10 is maintained. Further, the third node D is connected to the second node C via the third holding member 16. The third holding member 16 holds the third node D so that it can tilt with respect to the second node C and does not rotate about its axis, and is fixed to the third node D. The state in which the bevel gear 12 is engaged with the fifth bevel gear 11 is maintained.
By these first holding member 14, second holding member 15, and third holding member 16, the first node B, the second node C, and the third node D are held so as not to be detached from the multi-degree-of-freedom actuator A. .

The first joint B, the second joint C, and the third joint D in the joint mechanism of FIG. 1 are omitted, and the first bevel gear 6, the second bevel gear 8, and the third bevel gear. 9, the positional relationship among the fourth bevel gear 10, the fifth bevel gear 11, and the sixth bevel gear 12 is clarified in FIG. 2.
The axis S1 of the second joint is disposed perpendicular to the output shaft member 5, the axis S2 of the third joint is parallel to the axis S1 of the second joint, and the fourth bevel gear 10 And the fifth bevel gear 11 is disposed perpendicular to the axis of the bevel gear 11.
Further, the third bevel gear 9, the fourth bevel gear 10, the fifth bevel gear 11, and the sixth bevel gear 12 are coupled to transmit the drive of the second joint to the third joint. Means are configured.

  Next, as shown in FIG. 3, the multi-degree-of-freedom actuator A used as a drive source for this joint mechanism is composed of an ultrasonic actuator that rotates the rotor 4 using ultrasonic vibration. A cylindrical composite vibrator 3 is sandwiched between the base block 1 and the stator 2, and the base block 1 and the stator 2 are connected to each other via a connecting bolt 17 passed through the composite vibrator 3. Thus, the multi-degree-of-freedom actuator A as a whole has a substantially cylindrical outer shape. Here, for convenience of explanation, the central axis of the cylindrical outer shape from the base block 1 to the stator 2 is defined as the Z axis, and the X axis is perpendicular to the Z axis and the Z axis and the X axis are Assume that the Y-axis extends vertically.

  The composite vibrator 3 includes first to third piezoelectric element portions 31 to 33 each having a flat plate shape, which are positioned on the XY plane and overlapped with each other. The piezoelectric element portions 31 to 33 are insulating sheets. It is arranged in a state of being insulated from the stator 2 and the base block 1 through 34 to 37 and from each other.

A recess 18 is formed on the stator 2 on the side opposite to the surface in contact with the composite vibrator 3, and the spherical rotor 4 is accommodated in the recess 18. The recess 18 includes a small-diameter portion 19 having an inner diameter smaller than the diameter of the rotor 4 and a large-diameter portion 20 having an inner diameter larger than the diameter of the rotor 4. An annular step 21 located on the plane is formed. The rotor 4 is rotatably supported by contacting the step 21 in the recess 18.
The rotor 4 is in pressure contact with the stator 2 by a preload means (not shown).

  As shown in FIG. 4, the first piezoelectric element portion 31 of the composite vibrator 3 includes an electrode plate 31a, a piezoelectric element plate 31b, an electrode plate 31c, a piezoelectric element plate 31d, and an electrode plate 31e each having a disk shape. It has a structure that is sequentially stacked. Similarly, the second piezoelectric element portion 32 has a structure in which an electrode plate 32a, a piezoelectric element plate 32b, an electrode plate 32c, a piezoelectric element plate 32d, and an electrode plate 32e each having a disk shape are sequentially stacked. 3 has a structure in which an electrode plate 33a, a piezoelectric element plate 33b, an electrode plate 33c, a piezoelectric element plate 33d, and an electrode plate 33e each having a disk shape are sequentially stacked.

As shown in FIG. 5, the pair of piezoelectric element plates 31 b and 31 d of the first piezoelectric element portion 31 has portions that are divided into two in the Y-axis direction and have opposite polarities, and each has a Z-axis direction (thickness direction). The piezoelectric element plate 31b and the piezoelectric element plate 31d are disposed so as to be reversed with respect to each other.
The pair of piezoelectric element plates 32b and 32d of the second piezoelectric element portion 32 are polarized so as to be expanded or contracted in the Z-axis direction (thickness direction) as a whole without being divided into two. The element plate 32b and the piezoelectric element plate 32d are arranged inside out.
In the pair of piezoelectric element plates 33b and 33d of the third piezoelectric element portion 33, the portions divided into two in the X-axis direction have opposite polarities, and are opposite to expansion and contraction in the Z-axis direction (thickness direction), respectively. The piezoelectric element plate 33b and the piezoelectric element plate 33d are disposed so as to be reversed with respect to each other.

  As shown in FIG. 3, electrode plates 31 a and 31 e disposed on both surface portions of the first piezoelectric element portion 31 and electrodes disposed on both surface portions of the second piezoelectric element portion 32. The plate 32a and the electrode plate 32e, and the electrode plate 33a and the electrode plate 33e disposed on both surface portions of the third piezoelectric element portion 33 are electrically grounded. In addition, the first terminal 31 t from the electrode plate 31 c disposed between the pair of piezoelectric element plates 31 b and 31 d of the first piezoelectric element portion 31 is connected to the pair of piezoelectric element plates 32 b of the second piezoelectric element portion 32. And the second terminal 32t from the electrode plate 32c disposed between the second and third electrode elements 32c and 32d to the third terminal from the electrode plate 33c disposed between the pair of piezoelectric element plates 33b and 33d of the third piezoelectric element portion 33. Terminals 33t are respectively drawn out.

  Here, when an AC voltage having a frequency close to the natural frequency of the stator 2 is applied from the first terminal 31 t to the composite vibrator 3, the pair of piezoelectric element plates 31 b and 31 d of the first piezoelectric element unit 31 is applied. The two parts are alternately expanded and contracted in the Z-axis direction, and the stator 2 generates a flexural vibration in the Y-axis direction. Further, when an AC voltage having a frequency close to the natural frequency of the stator 2 is applied from the second terminal 32t, the pair of piezoelectric element plates 32b and 32d of the second piezoelectric element portion 32 repeatedly expands and contracts in the Z-axis direction. The stator 2 generates longitudinal vibration in the Z-axis direction. Further, when an AC voltage having a frequency close to the natural frequency of the stator 2 is applied from the third terminal 33t, the two divided portions of the pair of piezoelectric element plates 33b and 33d of the third piezoelectric element portion 33 are in the Z-axis direction. Then, expansion and contraction are alternately repeated, and flexural vibration in the X-axis direction is generated in the stator 2.

  Therefore, by driving the composite vibrator 3, flexural vibration in the Y-axis direction by the first piezoelectric element portion 31, longitudinal vibration in the Z-axis direction by the second piezoelectric element portion 32, and the third piezoelectric element portion 33. The rotor 4 is freely rotationally driven in a three-dimensional direction by generating a composite vibration in which two or all of the three flexural vibrations in the X-axis direction are combined to form an elliptical vibration in the step 21 of the stator 2. It is configured to be able to.

  Next, the operation of the joint mechanism of the robot according to this embodiment will be described. When the rotor 4 is rotated by driving the composite vibrator 3 of the multi-degree-of-freedom actuator A, and the output shaft member 5 is tilted with respect to the stator 2 using the rotor 4 as the first joint, the second joint and the second joint The three joints are not driven. Therefore, as the output shaft member 5 tilts, the first joint B, the second joint C, and the third joint D tilt relative to the stator 2 while maintaining their relative postures. Is done.

Further, when the rotor 4 is rotated by driving the composite vibrator 3 of the multi-degree-of-freedom actuator A and the output shaft member 5 is rotated about its own axis, the output shaft member 5 is rotated along its axis. Thus, the first bevel gear 6 is rotated. With the rotation of the first bevel gear 6, the second bevel gear 8 is rotated around the axis S <b> 1 of the second joint, whereby the second bevel gear 8 is fixed to the second bevel gear 8. The node C is tilted with respect to the first node B via the second joint.
The third bevel gear 9 is also rotated with the rotation of the first bevel gear 6, and the fourth bevel gear 10 and the fifth bevel are rotated with the rotation of the third bevel gear 9. The tooth gear 11 is rotated, and the sixth bevel gear 12 is rotated around the axis S2 of the third joint in accordance with the rotation of the fifth bevel gear 11, whereby the sixth bevel gear is rotated. The third joint D fixed to 12 is tilted with respect to the second joint C via the third joint.

Thus, by rotating the rotor 4 and rotating the output shaft member 5 about its axis, the second joint and the third joint are driven to tilt the second joint C relative to the first joint B. At the same time, the third joint D can be tilted with respect to the second joint C in conjunction therewith.
Further, since the second bevel gear 8 and the sixth bevel gear 12 are configured to rotate in the same direction, when the second node C is bent with respect to the first node B, The third node D is also bent in the same direction with respect to the second node C, and when the second node C is stretched linearly with respect to the first node B, the third node D is also relative to the second node C. Will be stretched linearly. Therefore, if the rotor 4 as the first joint is used as the joint at the base of the finger of the robot hand, the second joint C and the third joint D are tilted in the same direction, thereby performing a movement similar to a human finger. Hand fingers can be realized.

  If the rotor 4 of the multi-degree-of-freedom actuator A is rotated to simultaneously tilt the output shaft member 5 relative to the stator 2 and rotate the output shaft member 5 about its axis, the first node B is moved relative to the stator 2. The second joint C can be tilted with respect to the first joint B, and the third joint D can be tilted with respect to the second joint C.

  As described above, by rotating the rotor 4 of the multi-degree-of-freedom actuator A and tilting the output shaft member 5 with respect to the stator 2, the first joint B, the second joint C, and the second joint with the rotor 4 as the first joint. The third joint D can be tilted with respect to the stator 2 while maintaining the relative posture of each other, and the output shaft member 5 is rotated around its axis to drive the second joint and the third joint. The second node C can be tilted with respect to the first node B, and the third node D can be tilted with respect to the second node C.

As a result, the entire joint mechanism can be bent and extended by driving a plurality of joints using one multi-degree-of-freedom actuator A as a drive source.
Therefore, it is not necessary to provide a plurality of drive motors corresponding to a plurality of joints as in the conventional case, and a joint mechanism having a simple configuration can be realized.
Further, since it has only one multi-degree-of-freedom actuator A as a drive source, a plurality of power sources for supplying power, a control circuit for control, and a control sensor such as a position sensor used at the time of control are provided. Each of the joints can be driven and controlled, thereby further simplifying the configuration.

  Further, in this joint mechanism, the second joint C and the third joint D can be tilted by driving the second joint and the third joint, respectively, by utilizing the rotation of the output shaft member 5 around the axis. Therefore, it is not necessary to provide a motor for driving the second joint and a motor for driving the third joint in the first section B to the third section D, and so on. Each of the three sections D can be configured to be lightweight, and controllability is improved. Further, since it is not necessary to route power supply wiring and drive control wiring connected to the motor in the first section B to the third section D, the wiring in the first section B to the third section D is not necessary. Each structure can be simplified.

  Further, the first holding member 14 holds the first node B against the stator 2 so as not to rotate about its axis, and the second holding member 15 prevents the second node C from rotating about its axis. The second bevel gear fixed to the second node C when the first bevel gear 6 is rotated by the rotation of the output shaft member 5 around its axis because it is held against the node B. 8 is prevented from rotating around the axis of the first bevel gear 6 together with the first bevel gear 6. Therefore, the rotation of the first bevel gear 6 causes the second bevel gear 8 to rotate about the axis S1 of the second joint, thereby driving the second joint and moving the second joint C into the first joint B. Can be tilted with respect to.

  Further, since the third node D is held by the third holding member 16 with respect to the second node C so as not to rotate about its axis, the rotation of the output shaft member 5 about its axis causes the first bevel tooth A sixth bevel gear 12 fixed to the third node D when the fifth bevel gear 11 rotates via the gear 6, the third bevel gear 9, and the fourth bevel gear 10. Is prevented from rotating around the axis of the fifth bevel gear 11 together with the fifth bevel gear 11. Accordingly, the rotation of the fifth bevel gear 11 causes the sixth bevel gear 12 to rotate about the axis S2 of the third joint, thereby driving the third joint and moving the third joint D to the second joint C. Can be tilted with respect to.

  In the above-described embodiment, by selecting the ratio of the number of teeth of the bevel gears meshing with each other, the second speed relative to the rotation speed of the output shaft member 5 is driven when the second joint and the third joint are driven. The tilt speed of the node C and the tilt speed of the third node D can be set to desired values.

  The joint mechanism of the above embodiment has three joints. From this joint mechanism, the third joint D, the sixth bevel gear 12, the third bevel gear 9, and the fourth bevel. The joint gear having only two joints may be configured by omitting the tooth gear 10 and the fifth bevel gear 11.

  Further, with respect to the joint mechanism of the two joints, n ≧ 3, and the third to n-th nodes are sequentially connected to the tip of the second node C via the third to n-th joints, and the third bevel gear 9, rotation of the output shaft member 5 around its axis by using (n−2) interlocking means including the fourth bevel gear 10, the fifth bevel gear 11 and the sixth bevel gear 12. The driving of the second joint can be sequentially transmitted to the third to n-th joints.

  Further, in the above-described embodiment, instead of using interlocking means composed of the third bevel gear 9, the fourth bevel gear 10, the fifth bevel gear 11, and the sixth bevel gear 12, FIG. 6, the third bevel gear 9, the first pulley 41 fixed to the outer surface of the third bevel gear 9, and the third joint D fixed on the third joint axis S <b> 2. It is also possible to use interlocking means composed of the second pulley 42 and the belt 43 wound around the first pulley 41 and the second pulley 42. That is, as the first bevel gear 6 rotates, the second bevel gear 8 rotates and the third bevel gear 9 and the first pulley 41 rotate. Due to the rotation, the second pulley 42 is rotated in the same direction as the second bevel gear 8 via the belt 43, whereby the drive of the second joint can be transmitted to the third joint.

In addition, by selecting the size and shape of the first pulley 41 and the second pulley 42, the tilt speed of the second joint C relative to the output shaft member 5 and the third speed can be increased when the second joint and the third joint are driven. The tilting speed of the node D can be set to a desired value.
Also, for example, if at least one of the first pulley 41 and the second pulley 42 is not a perfect circle but an ellipse or the like whose radius changes according to the rotation angle, it depends on the rotational position of these pulleys. The tilting speed of the third section D with respect to the second section C can be changed.
A sprocket and a chain may be used instead of the pulley and the belt.

  In addition, as this interlocking means, it is also possible to use various link mechanisms that can sequentially transmit the drive of the second joint to the third to n-th joints when n ≧ 3.

  Further, in the above-described embodiment, instead of using the interlocking means, the output shaft member 5, the first bevel gear 6 and the second bevel gear 8 are connected to the first shaft means 51 as shown in FIG. The second shaft means 52 having the same configuration as the first shaft means 51 is prepared, and the universal joint 53 is provided at the tip of the first bevel gear 6 of the output shaft member 5 of the first shaft means 51. The output shaft member 5 of the second shaft means 52 is connected to the second shaft means 52, and the second bevel gear 8 of the second shaft means 52 is fixed to the third joint D on the axis S2 of the third joint. You can also. The universal joint 53 connects the output shaft member 5 of the first shaft means 51 and the output shaft member 5 of the second shaft means 52 so as to transmit a rotational motion around the axis while being tiltable with respect to each other. .

  With this configuration, when the output shaft member 5 of the first shaft means 51 is rotated about its axis, the output shaft member 5 of the second shaft means 52 is also rotated about its own axis via the universal joint 53. Thus, the second bevel gear 8 of the second shaft means 52 is the same as the second bevel gear 8 of the first shaft means 51 via the first bevel gear 6 of the second shaft means 52. Will be rotated in the direction. Therefore, by rotating the rotor 4 and rotating the output shaft member 5 of the first shaft means 51 about its axis, the second joint and the third joint are driven in conjunction with each other, and the second joint C is moved to the first joint. The third joint D can be tilted with respect to the second joint C with respect to B.

  Similarly, assuming that n ≧ 3, (n−2) output shaft members 5 of the second to (n−1) th shaft means are provided at the tip of the first bevel gear 6 of the first shaft means 51. If the second bevel gear 8 of the (n-1) -th axis means is fixed to the n-th node on the n-th joint axis, the rotor 4 is rotated and the first joint is rotated. By rotating the output shaft member 5 of the shaft means 51 around its axis, the third to n-th joints can be driven.

In the above-described embodiment, the direction in which the second node C is tilted with respect to the first node B and the direction in which the third node D is tilted with respect to the second node C are the same. The direction in which the second node C is tilted with respect to the first node B is opposite to the direction in which the third node D is tilted with respect to the second node C. It can also be configured as follows.
The direction in which the n-th node is tilted with respect to the (n−1) -th node when n ≧ 3 is the same as the direction in which the (n−1) -th node is tilted with respect to the (n−2) -th node. It can be configured to be in the direction or in the opposite direction.

  Note that this joint mechanism can be applied not only to the fingers of the robot hand but also to various parts having a plurality of joints such as robot legs.

In the multi-degree-of-freedom actuator A according to the above-described embodiment, the contact between the stator 2 and the rotor 4 is the step 21, but the configuration is not limited to this. If the elliptical motion can be transmitted, the contact may be made on a flat surface, the contact may be made on a curved surface, or may not be annular.
In the above embodiment, instead of the longitudinal vibration in the Z-axis direction and the flexural vibration in the Y-axis direction or the X-axis direction, a composite vibration that combines a plurality of vibrations that are not orthogonal to each other is generated to rotate the rotor 4. You can also.
Further, in the above-described embodiment, the flexural vibration in the X-axis direction, the flexural vibration in the Y-axis direction, and the vertical vibration in the Z-axis direction are generated in separate piezoelectric element units, and the combined vibration is generated by combining the vibrations. However, a single piezoelectric element portion may be polarized into a plurality of pieces, and the voltage applied to each polarization electrode may be individually controlled. That is, a composite vibration may be generated by a single piezoelectric element portion by applying a voltage obtained by synthesizing alternating voltages having different phases and amplitudes to each polarization electrode.
Further, although the elliptical motion is generated at the contact portion between the stator 2 and the rotor 4, the circular motion may be generated by controlling the amplitude in each axial direction.

It is a partially broken perspective view which shows the joint mechanism of the robot which concerns on embodiment of this invention. It is a fragmentary perspective view which shows what abbreviate | omitted a part of joint mechanism in FIG. It is sectional drawing which shows the multi-degree-of-freedom actuator in embodiment. It is a fragmentary sectional view showing the composition of the compound vibrator used in an embodiment. It is a perspective view which shows the polarization direction of three pairs of piezoelectric element plates of the composite vibrator used in the embodiment. It is a fragmentary perspective view which shows the joint mechanism of the robot which concerns on the modification of embodiment. It is a partial side view which shows the joint mechanism of the robot which concerns on another modification of embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Base block, 2 Stator, 3 Composite vibrator, 4 Rotor, 5 Output shaft member, 6 1st bevel gear, 7 Plate, 8 2nd bevel gear, 9 3rd bevel gear, 10 4th Bevel gears, 11 fifth bevel gears, 12 sixth bevel gears, 13 bearings, 14 first holding members, 15 second holding members, 16 third holding members, 18 recesses, 21 corners, 31 1st piezoelectric element part, 32 2nd piezoelectric element part, 33 3rd piezoelectric element part, 41 1st pulley, 42 2nd pulley, 43 belt, 51 1st axis means, 52 2nd axis means, 53 Universal joint, A Multi-degree-of-freedom actuator, B Section 1, C Section 2, D Section 3, S1 Second joint axis, S2 Third joint axis.

Claims (5)

A multi-degree-of-freedom actuator having a stator and a substantially spherical rotor disposed in contact with the stator and used as a first joint, and rotating the rotor around a plurality of axes by vibrating the stator;
A first node formed in an axial direction of an output shaft member formed to protrude from the surface of the rotor of the multi-degree-of-freedom actuator;
A second node connected to the tip of the first node via a second joint so as to be tiltable;
Conversion means for driving the second joint by the rotational movement of the output shaft member around its axis to tilt the second joint relative to the first joint;
Holding means for holding the second joint so that the second joint does not rotate with the output shaft member as the output shaft member rotates about its axis, and rotates the rotor of the multi-degree-of-freedom actuator. By tilting the output shaft member with respect to the stator, the first joint and the second joint can be tilted with respect to the stator while maintaining the relative posture of each other without driving the second joint. And rotating the output shaft member about its axis to drive the second joint via the conversion means to tilt the second joint relative to the first joint. mechanism.   The converting means includes a first bevel gear fixed to the tip of the output shaft member, and a first bevel gear fixed to the second joint on the shaft of the second joint and meshing with the first bevel gear. The joint mechanism of the robot according to claim 1, comprising two bevel gears.   The holding means is capable of tilting the first node relative to the stator and holding the first node so as not to rotate about its axis, and tilting the second node relative to the first node. The robot joint mechanism according to claim 1, further comprising a second holding member that holds the shaft so as not to rotate about the axis.   As n ≧ 3, the third to n-th nodes are sequentially connected to the tip of the second node via the third to n-th joints, and the driving of the second joint is sequentially transmitted to the third to n-th joints. The robot joint mechanism according to any one of claims 1 to 3, further comprising means.   The multi-degree-of-freedom actuator has a composite vibrator composed of a plurality of piezoelectric element plates stacked on each other, and the stator is vibrated by the composite vibrator to cause an elliptical or circular motion at a contact portion between the stator and the rotor. The robot joint mechanism according to any one of claims 1 to 4, wherein the rotor is rotated around a plurality of axes by being generated.

Images