JP6921406B2 - Ultrasonic motors, robot arms, and mesh robots - Google Patents

Description

The present invention relates to an ultrasonic motor, a robot arm equipped with the ultrasonic motor, and a mesh robot equipped with the ultrasonic motor.

An ultrasonic motor is a motor that uses ultrasonic vibration as a drive source without using a coil or a magnet. The advantages of ultrasonic motors are that they can generate high torque at low speeds, maintain self-holding characteristics even when the power is turned off, are compact and lightweight, do not require a reducer, are highly responsive, and are not affected by magnetic or electric fields. And so on. Further, the ultrasonic motor has a relatively simple structure and is suitable for miniaturization because it does not have a coil. Therefore, it is suitable for medical devices used under a high magnetic field such as robot joints and MRI.

Patent Document 1 describes an ultrasonic motor having a structure in which a through hole is formed in a rectangular parallelepiped metal (stator) and a cylindrical rotor shaft is passed through the metal (stator). A piezoelectric element is attached to the surface of the stator, and the ultrasonic motor generates a vibration wave on the inner surface of the through hole by the piezoelectric element to rotate the rotor shaft.

In an ultrasonic motor, the output torque and the number of revolutions are determined by the pressing force between the through hole and the rotor shaft. For example, when the pressing force between the through hole and the rotor shaft is large, the ultrasonic motor can obtain a large output torque. In order to increase the pressing force between the through hole and the rotor shaft, the through hole and the rotor shaft must be fitted without a gap.

Japanese Unexamined Patent Publication No. 2009-261494

However, the amplitude of the vibration wave generated on the inner surface of the through hole by the piezoelectric element is as small as several microns at the maximum. On the other hand, it is difficult to process both with an accuracy of several microns so that the through hole and the rotor shaft fit without a gap. Therefore, when an ultrasonic motor is mounted on a robot or the like that requires high operation accuracy, it is difficult to adjust characteristics such as output torque and rotation speed to desired values. Especially when the ultrasonic motor is small, this problem becomes remarkable.

Based on the above circumstances, the present invention provides an ultrasonic motor capable of adjusting characteristics such as output torque and rotation speed, a robot arm equipped with the ultrasonic motor, and a mesh robot equipped with the ultrasonic motor. The purpose.

In order to solve the above problems, the present invention proposes the following means.
The ultrasonic motor of the present invention includes a rotor shaft having a cylindrical first shaft, a cylindrical second shaft, a first opening which is an opening on the proximal end side of the first shaft, and the above. An elastic member that applies a force in a direction to bring the second opening, which is an opening on the base end side of the second shaft, closer to the second shaft, a rectangular parallelepiped stator having a through hole through which the rotor shaft penetrates, and an outer surface of the stator. The first shaft and the second shaft are provided with the first opening and the second opening facing each other, and the inside of the stator. The peripheral surface is tapered, the first shaft has a first engaging portion that is tapered on the outer periphery on the proximal end side, and the second shaft is tapered on the outer periphery on the proximal end side. It has a second engaging portion, and the inner peripheral surface of the stator is engaged with the first engaging portion and the second engaging portion.

The robot arm of the present invention is a robot arm having a plurality of the ultrasonic motors and including a connecting member for connecting the ultrasonic motors to each other.

The mesh robot of the present invention includes a plate having a plurality of the robot arms, having flexibility, and connecting the plurality of the robot arms.

According to the ultrasonic motor of the present invention, characteristics such as output torque and rotation speed can be adjusted to desired values. Further, according to the robot arm and the mesh robot of the present invention, an ultrasonic motor that is ultra-compact and has a large output torque can be mounted, and the operating characteristics can be adjusted to a desired value.

It is a perspective view which shows the whole structure of the ultrasonic motor which concerns on 1st Embodiment of this invention. It is a perspective view which shows the structure which removed a part of the ultrasonic motor which concerns on 1st Embodiment of this invention. It is an exploded view of the ultrasonic motor which concerns on 1st Embodiment of this invention. It is an exploded view of the structure which removed a part of the ultrasonic motor which concerns on 1st Embodiment of this invention. It is a side view which looked at the ultrasonic motor which concerns on 1st Embodiment of this invention from the direction perpendicular to the axial direction. FIG. 5 is a cross-sectional view of FIG. It is a side view which looked at the ultrasonic motor which concerns on 2nd Embodiment of this invention from the direction perpendicular to the axial direction. FIG. 7 is a cross-sectional view of FIG. It is a perspective view which shows the whole structure of the robot arm which concerns on 3rd Embodiment of this invention. It is a perspective view which looked at the whole structure of the robot arm which concerns on 3rd Embodiment of this invention from the side opposite to FIG. It is a perspective view which shows the whole structure of the mesh robot which concerns on 4th Embodiment of this invention. It is a perspective view which shows the whole structure of the robot arm of the mesh robot which concerns on 4th Embodiment of this invention. It is a perspective view which shows the structure of the plate of the mesh robot which concerns on 4th Embodiment of this invention. It is a figure which shows the connection of the plate of the mesh robot which concerns on 4th Embodiment of this invention, and a robot arm. It is a figure which shows the minimum structure of the mesh robot which concerns on 4th Embodiment of this invention. It is a perspective view which shows the use example of the mesh robot which concerns on 4th Embodiment of this invention. It is a perspective view which shows the use example of the mesh robot which concerns on 4th Embodiment of this invention. It is a graph which shows an example of the compliance control of the mesh robot which concerns on 4th Embodiment of this invention.

(First Embodiment)
The first embodiment of the present invention will be described with reference to FIGS. 1 to 6. In order to make the drawings easier to see, the thickness and dimensional ratio of each component are adjusted as appropriate.

FIG. 1 is a perspective view showing the overall configuration of the ultrasonic motor 100 according to the first embodiment. FIG. 2 is a perspective view showing a configuration in which a part of the ultrasonic motor 100 shown in FIG. 1 is removed.
The ultrasonic motor 100 includes a stator 1, a piezoelectric element (ultrasonic wave generating element) 2, a rotor shaft 3, a spring fixing member 4, and a spring (elastic member) 5.
The ultrasonic motor 100 operates as a rotary motor in which the rotor shaft 3 rotates about the longitudinal axis of the rotor shaft 3. In the following description, the axial direction of the rotor shaft 3 is referred to as "axial direction A", and the rotational direction of the rotor shaft 3 is referred to as "rotation direction R".

As shown in FIG. 1, the stator 1 is formed in a rectangular parallelepiped shape and has a through hole H penetrating the facing side surfaces. Further, the outer peripheral contour of the cross section perpendicular to the axial direction A of the stator 1 is a quadrangle. The rotor shaft 3 is arranged so as to pass through the through hole H.
The stator 1 is formed in a rectangular parallelepiped having a square shape of, for example, 2 to 3 mm. Further, the constituent material of the stator 1 is generally a metal material (iron, stainless steel, aluminum, copper, etc.), but it does not necessarily have to be a metal and may be a plastic.

FIG. 3 is an exploded view of the ultrasonic motor 100 according to the first embodiment. FIG. 4 is an exploded view showing a configuration in which a part of the ultrasonic motor 100 shown in FIG. 3 is removed.
As shown in FIGS. 3 and 4, a plurality of grooves T are formed on the inner peripheral surface 10 of the stator 1 along the axial direction A. The plurality of grooves T are arranged at equal intervals along the circumferential direction of the inner peripheral surface 10 of the stator 1. The shapes of the grooves T are equal to each other and are substantially cylindrical.

FIG. 5 is a side view of the ultrasonic motor 100 according to the first embodiment as viewed from a direction perpendicular to the axial direction A. FIG. 6 is a cross-sectional view of FIG.
As shown in FIGS. 5 and 6, the through hole H of the stator 1 has a substantially cylindrical shape. The inner peripheral surface 10 of the stator 1 is machined into a tapered shape so that the diameter dimension of the openings at both ends of the through hole H is the largest and the diameter dimension becomes smaller toward the central portion in the axial direction A from the openings at both ends. ing. As shown in FIG. 6, in the cross section horizontal to the axial direction A of the stator 1, the inner peripheral surface 10 is formed in a wedge shape. The angle of the taper is about 2 to 15 degrees with respect to the axial direction A.

As shown in FIG. 2, the inner peripheral surface 10 of the stator 1 has a first inner peripheral surface 11 that engages with the first shaft 31 and a second inner peripheral surface 12 that engages with the second shaft 32. .. As shown in FIGS. 2, 4, and 6, the first inner peripheral surface 11 is a portion of the inner peripheral surface 10 from the central portion in the axial direction A toward one opening. On the other hand, as shown in FIGS. 2, 4, and 6, the second inner peripheral surface 12 is located on the opposite side of the first inner peripheral surface 11 of the inner peripheral surface 10 with the central portion in the axial direction A interposed therebetween. It is a located portion, which is a portion from the central portion in the axial direction A toward the other opening.

As shown in FIG. 4, the groove T is formed so that the depth in the vertical direction is constant along the tapered shape. The grooves T are formed separately even in the central portion in the axial direction A where the diameter dimension of the through hole H is the smallest, without contacting each other.

The piezoelectric element 2 is an element that generates ultrasonic waves such as ceramics. As shown in FIG. 1, the piezoelectric element 2 is attached to each of the four outer surfaces horizontal to the axial direction A of the stator 1. An AC voltage in the ultrasonic region is input to the piezoelectric element 2. The four piezoelectric elements 2 generate ultrasonic waves that are out of phase by 90 degrees, and generate a traveling wave in the rotation direction R on the inner surface of the through hole H.

The rotor shaft 3 has a first shaft 31 and a second shaft 32. The spring fixing member 4 includes a first spring fixing member 41 and a second spring fixing member 42.

The first shaft 31 and the second shaft 32 are formed in a substantially cylindrical shape, and both ends are open. As shown in FIGS. 3 and 4, the first shaft 31 and the second shaft 32 have a base end opening (first opening) 31a of the first shaft 31 and a base end opening (second opening) of the second shaft 32. The opening) 32a is provided so as to face each other and communicate with the internal space.
The tip opening 31b of the first shaft 31 and the tip opening 32b of the second shaft 32 are not always necessary and may not be provided.

The first spring fixing member 41 is a cylindrical member that engages with the first shaft 31, and is a member to which one end of the spring 5, which will be described later, is attached. That is, the first spring fixing member 41 is an auxiliary member that assists the connection between the spring 5 and the first shaft 31. The first spring fixing member 41 has a shape other than a cylindrical shape, for example, a prism shape, a hook shape, or the like, as long as it has a shape that can be engaged with the first shaft 31 and the end portion of the spring 5 can be attached. You may.

The second spring fixing member 42 is a cylindrical member that engages with the second shaft 32, and is a member to which the other end of the spring 5, which will be described later, is attached. That is, the second spring fixing member 42 is an auxiliary member that assists the connection between the spring 5 and the second shaft 32. The second spring fixing member 42 has a shape other than a cylindrical shape, for example, a prism shape or a hook shape, as long as it can engage with the second shaft 32 and the end portion of the spring 5 can be attached. You may.

As shown in FIGS. 2 and 6, the spring 5 is arranged in an internal space that communicates the internal space of the first shaft 31 and the internal space of the second shaft 32. One end is attached to the first spring fixing member 41 and the other end is attached to the second spring fixing member 42. The spring 5 applies an elastic force in a direction in which the first shaft 31 and the second shaft 32 are brought closer to each other along the axial direction A.

The pair of first locking holes 31c are holes provided in the first shaft 31, and as shown in FIGS. 1 and 2, the first spring fixing member 41 having a cylindrical shape is locked. As shown in FIGS. 1 to 6, the pair of first locking holes 31c are provided at locations facing each other with the longitudinal axis of the first shaft 31 interposed therebetween. Each of the pair of first locking holes 31c penetrates the side surface of the first shaft 31.

The pair of first locking holes 31c have a plurality of holes through which the first spring fixing member can penetrate in order to change the position where the first spring fixing member 41 is locked along the axial direction A. By changing the holes of the pair of first locking holes 31c through which the first spring fixing member penetrates, the position where the first spring fixing member 41 is locked is changed. By changing the position where the first spring fixing member 41 is locked, the magnitude of the elastic force of the spring 5 that brings the first shaft 31 and the second shaft 32 closer to each other can be changed.
Of course, by changing the spring 5 itself to a spring 5 having a different elastic force, the magnitude of the elastic force that brings the first shaft 31 and the second shaft 32 closer to each other may be adjusted.

The pair of second locking holes 32c are holes provided in the second shaft 32, and as shown in FIGS. 1 and 2, the cylindrical second spring fixing member 42 is locked. As shown in FIGS. 3 and 4, the pair of second locking holes 32c are provided at locations facing each other with the longitudinal axis of the second shaft 32 interposed therebetween. Each of the pair of second locking holes 32c penetrates the side surface of the second shaft 32.

As shown in FIG. 3, the first shaft 31 has a first engaging portion 31d on the outer periphery on the proximal end side. As shown in FIG. 6, the first inner peripheral surface 11 of the stator 1 and the first engaging portion 31d of the first shaft are arranged so as to face each other.
As shown in FIGS. 3 and 6, the first engaging portion 31d is processed into a tapered shape so that the diameter dimension becomes smaller toward the proximal end opening 31a. The tapered shape of the first engaging portion 31d is formed so as to engage with the tapered shape of the first inner peripheral surface 11 arranged so as to face each other.

As shown in FIG. 3, the second shaft 32 also has a second engaging portion 32d on the outer periphery on the proximal end side. As shown in FIG. 6, the second inner peripheral surface 12 of the stator 1 and the second engaging portion 32d of the second shaft are arranged so as to face each other.
As shown in FIGS. 3 and 6, the second engaging portion 32d is processed into a tapered shape so that the diameter dimension becomes smaller toward the proximal end opening 32a. The tapered shape of the second engaging portion 32d is formed so as to engage with the tapered shape of the second inner peripheral surface 12 arranged so as to face each other.

As shown in FIGS. 3 and 4, the first engaging portion 31d has a first convex portion 31e protruding in the axial direction A at the edge of the proximal end opening 31a. Further, the second engaging portion 32d also has a second convex portion 32e protruding in the axial direction A at the edge of the proximal end opening 32a.
With respect to the first convex portion 31e and the second convex portion 32e, when the first shaft 31 and the second shaft 32 rotate with the axial direction A as the rotation axis, at least one end of both ends in the rotation direction R is Engage.

When the first shaft 31 and the second shaft 32 are arranged so as to engage with the inner peripheral surface 10 of the stator 1, the first shaft 31 and the second shaft 32 are slightly between the first shaft 31 and the second shaft 32 in the axial direction A. The lengths of the first engaging portion 31d and the second engaging portion 32d in the axial direction A are adjusted so that a gap is formed in the first engaging portion 31d and the second engaging portion 32d. Therefore, by adjusting the elastic force of the spring 5, the relative positions of the first shaft 31 and the second shaft 32 are adjusted along the axial direction A.

By changing the holes of the pair of first locking holes 31c that lock the first spring fixing member 41, the elastic force of the spring 5 is adjusted, and the first inner peripheral surface 11 of the stator 1 and the first shaft The first engaging portion 31d can be engaged without a gap, and the second inner peripheral surface 12 of the stator 1 and the second engaging portion 32d of the second shaft can be engaged without a gap.

Next, the operation of the ultrasonic motor 100 will be described.
An AC voltage in the ultrasonic region is input to the piezoelectric element 2, and the piezoelectric element 2 generates ultrasonic waves. AC voltage is input to the four piezoelectric elements 2 so as to generate ultrasonic waves that are out of phase by 90 degrees. As a result, a traveling wave in the rotation direction R is generated on the inner peripheral surface 10 of the through hole H.

Due to the traveling wave of the rotation direction R generated by the piezoelectric element 2 on the inner peripheral surface 10 of the through hole H, the first convex portion 31e and the second convex portion 32e of the first shaft 31 and the second shaft 32 are in the rotation direction. Rotate while engaging at at least one end of both ends of R. By transmitting the rotational motion generated in one of the first shaft 31 and the second shaft 32 to the other, the rotational speeds of the first shaft 31 and the second shaft 32 can be made uniform.

Further, in the cross section horizontal to the axial direction A of the stator 1, the inner peripheral surface 10 is formed in a wedge shape. In the case of a stator whose inner peripheral surface does not have a wedge shape as in the conventional case, vibration can be transmitted only in the direction perpendicular to the axial direction A with respect to the rotor shaft.
On the other hand, when a tapered shape is formed on the inner peripheral surface 10 as in the stator 1 of the present embodiment, vibration is transmitted not only in the direction perpendicular to the axial direction A but also in the direction horizontal to the axial direction A. Can be done.
Conventionally, the only way to improve the vibration transmission efficiency is to improve the vibration transmission efficiency only in the direction perpendicular to the axial direction A. In the stator 1 of the present embodiment, the overall vibration transmission efficiency can be improved by improving the vibration transmission efficiency in the direction perpendicular to the axial direction A in combination with the direction perpendicular to the axial direction A.

Further, elastic force is applied to the first shaft 31 and the second shaft 32 in the direction of bringing them closer to each other by the spring 5. By adjusting the elastic force, the first inner peripheral surface 11 of the stator 1 and the first engaging portion 31d of the first shaft can be brought into contact with each other without a gap. Further, the second inner peripheral surface 12 of the stator 1 and the second engaging portion 32d of the second shaft can be brought into contact with each other without a gap. As a result, the traveling wave in the rotation direction R generated by the piezoelectric element 2 on the inner peripheral surface 10 of the through hole H can be transmitted to the first shaft 31 and the second shaft 32 with less loss, and the output torque can be reduced. It can be made larger.

A groove T is formed on the inner peripheral surface 10 of the stator 1. The ultrasonic motor 100 obtains a driving force by friction by bringing the rotor shaft 3 into contact with the elliptical movement of the inner peripheral surface of the stator accompanying the generation of a traveling wave. Since the groove T of the inner peripheral surface 10 is formed, the elliptical motion of the edge portion of the groove T comes into contact with the inner surface of the stator so as to be caught, so that reliable motion and force can be transmitted. The circumferential amplitude is increased and the rotational speed characteristic of the rotor shaft 3 is improved.

(Effect of the first embodiment)
According to the ultrasonic motor 100 of the present embodiment, a wedge shape is provided in a cross section horizontal to the axial direction A of the stator 1, and the vibration transmission efficiency to the rotor shaft can be improved. Further, the rotor shaft 3 is composed of the first shaft 31 and the second shaft 32, and is connected by the spring 5 to engage with the inner peripheral surface 10 of the stator 1 and the engaging portions (31d, 32d) of the rotor shaft 3. Can be brought into contact without gaps. Further, the contact force can be adjusted by the spring 5.

In the conventional ultrasonic motor, after the rotor shaft and the stator are machined and molded, there is no adjusting means for improving the vibration transmission efficiency when sufficient vibration transmission efficiency cannot be obtained due to the machining accuracy.
According to the ultrasonic motor 100 of the present embodiment, the force of bringing the first shaft 31 and the second shaft 32 closer to each other can be adjusted by the spring 5 and the spring fixing member 4, and the vibration transmission efficiency can be adjusted.

(Modification example)
Although the first embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like within a range that does not deviate from the gist of the present invention. .. In addition, the components shown in the above-described first embodiment and the modifications shown below can be appropriately combined and configured.

For example, the piezoelectric element 2 can be attached to two side surfaces of the stator 1 (either two adjacent side surfaces or two opposite side surfaces). Further, the ultrasonic wave generating element 13 can be attached to one side surface or three side surfaces. Further, a plurality of piezoelectric elements can be attached to each side surface. Any configuration may be used as long as it is configured to generate a traveling wave on the inner peripheral surface 10 of the through hole H.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. 7 and 8. In the following description, the same reference numerals will be given to the configurations common to those already described, and duplicate description will be omitted.
In the ultrasonic motor 100B according to the second embodiment, as compared with the ultrasonic motor 100, the spring is not an internal space in which the internal space of the first shaft 31 and the internal space of the second shaft 32 communicate with each other, but an external space. The difference is that they are placed in.

FIG. 7 is a side view of the ultrasonic motor 100B as viewed from a direction perpendicular to the axial direction A. FIG. 8 is a cross-sectional view of FIG. 7.
As shown in FIGS. 7 and 8, the ultrasonic motor 100B includes a stator 1, a piezoelectric element (ultrasonic wave generating element) 2, a rotor shaft 3, a spring fixing member 4B, a spring (elastic member) 5B, and the like. To be equipped.

In the second embodiment, the first shaft 31 is provided with a tip opening 31b, and the second shaft 32 is provided with a tip opening 32b.

The spring 5B has a disc spring 50 and a pair of disc-shaped members (51, 52), as shown in FIGS. 7 and 8.
The disc spring 50 is formed by forming a disk-shaped plate having a through hole in the center in a substantially conical shape. A pair of disc-shaped members (51, 52) having through holes in the center are provided on both sides of the disc spring 50 in the through hole direction so as to come into contact with a part of the disc spring 50. Specifically, the upper portion of the conical shape of the disc spring 50 is in contact with the disc-shaped member 52, and the lower portion of the conical shape of the spring 5B is in contact with the disc-shaped member 51.
The spring 5B has a spring effect of applying an elastic force in a direction of moving the disk-shaped member 51 and the disk-shaped member 52 away from each other when a load is applied in the direction of bringing the disk-shaped member 51 and the disk-shaped member 52 closer to each other.

The spring 5B has a through hole composed of a through hole of the disc spring 50 and a through hole of a pair of disc-shaped members (51, 52). The through holes of the disc spring 50 and the through holes of the pair of disc-shaped members (51, 52) have the same central axes, and the central axis is the central axis of the through holes of the spring 5B.

The spring 5B is arranged so that the central axis of the through hole of the spring 5B coincides with the longitudinal axis of the rotor shaft 3 and the disk-shaped member 51 contacts the surface of the first shaft 31 having the tip opening 31b. Will be done. Further, the spring 5B is arranged so that the through hole of the spring 5B communicates with the internal space of the first shaft 31.

As shown in FIGS. 7 and 8, the spring fixing member 4B has a nut (first spring fixing member) 43 and a bolt (second spring fixing member) 44.

The nut (first spring fixing member) 43 is a nut member having a through hole provided with a female screw on the inner peripheral surface.
In the nut 43, the surface having the through hole of the nut 43 is joined to the surface having the through hole of the disc-shaped member 52 so that the central axis of the through hole of the nut 43 coincides with the central axis of the through hole of the spring 5B. ing. Further, the nut 43 is joined to the spring 5B so that the through hole of the nut 43 communicates with the through hole of the spring 5B.

The bolt (second spring fixing member) 44 is a bolt member having a cylindrical portion 44a provided with a male screw on the outer peripheral surface and a head portion 44b. The cylindrical portion 44a can be fitted to the nut 43 by a male screw provided on the outer peripheral surface. It is sufficient that the male screw on the outer peripheral surface of the cylindrical portion 44a is provided at a portion that fits with the nut 43.
By changing the position of the bolt 44 to which the nut 43 is fitted, the relative position between the nut 43 and the bolt 44 can be adjusted.

The cylindrical portion 44a of the bolt 44 penetrates the internal space of the first shaft 31, the internal space of the second shaft 32, and the through hole of the spring 5B, and is fitted with a female screw provided on the inner surface of the nut 43. It fits. The longitudinal axis of the bolt 44 coincides with the longitudinal axis of the rotor shaft 3.
Further, the head portion 44b of the bolt 44 is joined to the surface of the second shaft 32 having the tip opening 32b.

The first shaft 31, the second shaft 32, and the spring 5B through which the bolt 44 penetrates are movably supported in the longitudinal axial direction of the bolt 44, that is, in the axial direction A. Further, the first shaft 31, the second shaft 32, and the spring 5B are rotatably supported in the rotation direction R about the longitudinal axis of the bolt 44.

The relative positions of the nut 43 and the bolt 44 are fixed, and the relative distance between the nut 43 and the head 44b of the bolt 44 is fixed.
Since the first shaft 31, the second shaft 32, and the spring 5B through which the bolt 44 penetrates are sandwiched between the nut 43 and the head 44b of the bolt 44, the range of movement in the axial direction A is limited. ..

Here, the relative positions of the nut 43 and the bolt 44 are adjusted so that the disc-shaped member 51 and the disc-shaped member 52 are close to each other, and the elasticity in the direction of moving the disc-shaped member 51 and the disc-shaped member 52 away from the spring 5B. Generate force.

By adjusting the relative positions of the nut 43 and the bolt 44, the spring 5B can apply an elastic force in the direction of bringing the first shaft 31 closer to the second shaft 32.
That is, the nut 43 and the bolt 44 are auxiliary members that assist the connection between the spring 5B and the first shaft 31.

By adjusting the relative positions of the nut 43 and the bolt 44, the spring 5B can apply an elastic force in the direction of bringing the second shaft 32 closer to the first shaft 31 via the nut 43 and the bolt 44.
That is, the nut 43 and the bolt 44 are auxiliary members that assist the connection between the spring 5B and the second shaft 32.

By adjusting the relative positions of the nut 43 and the bolt 44, the spring 5B applies an elastic force in the direction in which the first shaft 31 and the second shaft 32 are brought closer to each other along the axial direction A. Specifically, the spring 5B has a proximal end opening (first opening) 31a which is an opening on the proximal end side of the first shaft 31 and a proximal end which is an opening on the proximal end side of the second shaft 32. An elastic force is applied in the direction of bringing the opening (second opening) 32a closer to the opening (second opening) 32a.

When the first shaft 31 and the second shaft 32 are arranged so as to engage with the inner peripheral surface 10 of the stator 1, the first shaft 31 and the second shaft 32 are slightly between the first shaft 31 and the second shaft 32 in the axial direction A. The lengths of the first engaging portion 31d and the second engaging portion 32d in the axial direction A are adjusted so that a gap is formed in the first engaging portion 31d and the second engaging portion 32d. Therefore, by adjusting the relative positions of the nut 43 and the bolt 44, the relative positions of the first shaft 31 and the second shaft 32 are adjusted along the axial direction A.

As shown in FIGS. 7 and 8, a cylindrical rotation transmission member 9 is attached to the tip of the cylindrical portion 44a of the bolt 44. The longitudinal axis of the rotation transmission member 9 serves as the rotation axis, and the longitudinal axis of the rotation transmission member 9 coincides with the longitudinal axis of the bolt 44.

Next, the operation of the ultrasonic motor 100B will be described.
An AC voltage in the ultrasonic region is input to the piezoelectric element 2, and the piezoelectric element 2 generates ultrasonic waves. AC voltage is input to the four piezoelectric elements 2 so as to generate ultrasonic waves that are out of phase by 90 degrees. As a result, a traveling wave in the rotation direction R is generated on the inner peripheral surface 10 of the through hole H.

Due to the traveling wave in the rotation direction R generated by the piezoelectric element 2 on the inner peripheral surface 10 of the through hole H, the first convex portion 31e and the second convex portion 32e of the first shaft 31 and the second shaft 32 are in the rotation direction. Rotate while engaging at at least one end of both ends of R. By transmitting the rotational motion generated in one of the first shaft 31 and the second shaft 32 to the other, the rotational speeds of the first shaft 31 and the second shaft 32 can be made uniform.

The nut 43 and the bolt 44 sandwich the spring 5B and the rotor shaft 3, and the distance between the nut 43 and the bolt 44 is adjusted so that the elastic force of the spring acts on the spring 5B. Therefore, the spring 5B and the first shaft 31, and the head 44b and the second shaft 32 are in close contact with each other. Therefore, when the rotor shaft 3 rotates in the rotation direction R, the nut 43, the bolt 44, and the spring 5B rotate in the rotation direction R together with the rotation of the rotor shaft 3. The rotation transmission member 9 also rotates in the rotation direction R in accordance with the rotation of the bolt 44.

Further, in the cross section horizontal to the axial direction A of the stator 1, the inner peripheral surface 10 is formed in a wedge shape as in the first embodiment. When the inner peripheral surface 10 of the stator 1 is formed with a tapered shape, vibration can be transmitted not only in the direction perpendicular to the axial direction A but also in the direction horizontal to the axial direction A. In the stator 1 of the present embodiment, the overall vibration transmission efficiency can be improved by improving the vibration transmission efficiency in the direction perpendicular to the axial direction A in combination with the direction perpendicular to the axial direction A.

Further, elastic force is applied to the first shaft 31 and the second shaft 32 in the direction of bringing them closer to each other by the spring 5B. By adjusting the elastic force, the first inner peripheral surface 11 of the stator 1 and the first engaging portion 31d of the first shaft can be brought into contact with each other without a gap. Further, the second inner peripheral surface 12 of the stator 1 and the second engaging portion 32d of the second shaft can be brought into contact with each other without a gap. As a result, the traveling wave in the rotation direction R generated by the piezoelectric element 2 on the inner peripheral surface 10 of the through hole H can be transmitted to the first shaft 31 and the second shaft 32 with less loss, and the output torque can be reduced. It can be made larger.

(Effect of the second embodiment)
According to the ultrasonic motor 100B of the present embodiment, similarly to the ultrasonic motor 100 of the first embodiment, a wedge shape is provided in a cross section horizontal to the axial direction A of the stator 1, and the vibration transmission efficiency to the rotor shaft can be improved. Further, the rotor shaft 3 is composed of the first shaft 31 and the second shaft 32, and by bringing them close to each other by the spring 5B, the engaging portions (31d, 32d) between the inner peripheral surface 10 of the stator 1 and the rotor shaft 3 are formed. Can be brought into contact with each other without a gap. Further, the contact force can be adjusted by the spring 5B.

According to the ultrasonic motor 100B of the present embodiment, the spring 5B that brings the first shaft 31 and the second shaft 32 close to each other can be arranged not in the internal space of the first shaft 31 and the second shaft 32 but in the external space. , The ultrasonic motor 100B can be easily configured as compared with the ultrasonic motor 100. In particular, this effect becomes remarkable when the ultrasonic motor 100B is small.

According to the ultrasonic motor 100B of the present embodiment, the elastic force of the spring 5B is made finer by changing the relative positions of the nut 43 and the bolt 44 as compared with the ultrasonic motor 100 of the first embodiment. It can be changed at intervals. The gap between the inner peripheral surface 10 of the stator 1 and the engaging portions (31d, 32d) of the rotor shaft 3 can be adjusted with a finer particle size.

(Third Embodiment)
A third embodiment of the present invention will be described with reference to FIGS. 9 and 10. In the following description, the same reference numerals will be given to the configurations common to those already described, and duplicate description will be omitted.

FIG. 9 is a perspective view showing the overall configuration of the robot arm 200 according to the third embodiment. Further, FIG. 10 is a perspective view showing the overall configuration of the robot arm 200 as viewed from the side opposite to that of FIG. 9.

The robot arm 200 is an ultra-compact 6-DOF robot arm composed of 6 ultrasonic motors 100. The robot arm 200 is configured by arranging six ultrasonic motors 100 having one degree of freedom and connecting adjacent ultrasonic motors 100 with a connecting member 7.

As the configuration mode of the robot arm 200 by the six ultrasonic motors 100, a known configuration mode of the 6-DOF robot arm may be appropriately adopted. The robot arm 200 is configured so that the angle formed by the adjacent ultrasonic motors 100 can be calculated from the posture and position of the robot arm 200 by inverse kinematics.
The robot arm 200 is not limited to a robot arm having 6 degrees of freedom. The robot arm 200 may be a multi-DOF robot arm other than the 6-DOF robot arm.

The connecting member 7 is generally made of a metal material (iron, stainless steel, aluminum, copper, etc.), but it does not necessarily have to be a metal and may be a plastic. The connecting member 7 connects adjacent ultrasonic motors 100 so as not to hinder the vibration of the stator 1.

The robot arm 200 has, for example, a total length of about 18 mm and a payload of about 0.1 kg.

(Effect of Third Embodiment)
According to the robot arm 200 of the present embodiment, an ultra-compact robot arm 200 with 6 degrees of freedom can be realized by connecting and combining an ultra-compact ultrasonic motor 100 having a large output torque. The robot arm 200 can generate high torque at low speed, maintains self-holding characteristics even when the power is turned off, is compact and lightweight, does not require a speed reducer, has high responsiveness, and is not affected by magnetic fields or electric fields. It has merits and can be suitably used for robot joints and medical devices.

Although the third embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like within a range that does not deviate from the gist of the present invention. .. In addition, the components shown in the above-described third embodiment and modification can be appropriately combined and configured.

(Fourth Embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS. 11 to 18. In the following description, the same reference numerals will be given to the configurations common to those already described, and duplicate description will be omitted.

FIG. 11 is a perspective view showing the overall configuration of the mesh robot 300 according to the fourth embodiment.
The mesh robot 300 includes a disk-shaped plate 8 and a robot arm 200B that connects adjacent plates 8.

FIG. 12 is a perspective view showing the overall configuration of the robot arm 200B.
The robot arm 200B has a different configuration of the first shaft as compared with the robot arm 200 of the second embodiment. The first shaft 31B of the robot arm 200B is not provided with the tip opening 32b. Further, a semicircular notch 31e is formed at the tip when viewed from the axial direction A.

FIG. 13 is a perspective view showing the configuration of the plate back surface 8b of the plate 8.
The plate 8 has a disk shape and is composed of four divided plates 80. As shown in FIG. 13, the dividing plate 80 has a shape in which the disk shape is divided into four at every 90 degrees of the central angle. The adjacent dividing plates 80 are rotatably connected to each other with the tangent side as the central axis, and the connecting portion is urged by a spring or the like so that the normals of the adjacent dividing plates 80 are parallel to each other. Therefore, the plate 8 has flexibility like a leaf spring. Since the plate 8 has flexibility, it can absorb control errors in the posture and position of the robot arm 200B.

As shown in FIG. 13, recesses 81 are formed in each of the divided plates 80. A recess 81 is formed at a position that equally divides the circumferential direction of the plate 8. As shown in FIG. 14, a semicircular notch 81e is formed at the bottom of the recess 81.

As shown in FIG. 14, the recess 81 engages with the first shaft 31B at the tip of the robot arm 200B. By engaging the notch 31e of the first shaft 31B and the notch 81e of the recess 81, the inclination and vertical displacement of the robot arm 200B can be reliably transmitted to the plate 8.

FIG. 15 is a diagram showing a minimum configuration of a mesh robot 300 in which two plates 8 and one robot arm 200B are connected. As shown in FIG. 15, the inclination and vertical displacement of the two plates 8 can be changed by operating the robot arm 200B.

As shown in FIG. 11, the mesh robot 300 is configured by arranging 25 plates 8 in a grid pattern and connecting adjacent plates 8 with a robot arm 200B. The dimensions of the mesh robot 300 are, for example, 40 mm to 64 mm on each side.

16 and 17 are perspective views showing a usage example of the mesh robot 300. Note that in FIGS. 16 and 17, the robot arm 200B of the mesh robot 300 is not shown.
As shown in FIGS. 16 and 17, the mesh robot 300 transforms the surface created by the surfaces 8a of the plurality of plates 8 into various three-dimensional shapes by changing the inclination and displacement of the plate 8 by the robot arm 200. Can be made to.

Next, the operation of the mesh robot 300 will be described.
A controller (not shown) that controls the mesh robot 300 obtains the inclination and displacement of each plate 8 and obtains the posture and position of each robot arm 200B from the inclination and displacement. From the posture and position of the robot arm 200B, the angle formed by the adjacent ultrasonic motors 100 is calculated from inverse kinematics. The rotor shaft 3 of each ultrasonic motor 100 is rotated so that the angle formed by the adjacent ultrasonic motors 100 becomes the calculated angle.

Since the mesh robot 300 is equipped with an ultrasonic motor 100 that is ultra-compact and has a large output torque, compliance control that makes the person who touches the surface created by the surfaces 8a of the plurality of plates 8 feel as shown below. Is also possible.

FIG. 18 is a graph showing an example of compliance control of the mesh robot 300. The horizontal axis of the graph is the displacement of the plate 8 when a force is applied to the plate 8. The vertical axis of the graph shows the magnitude of the reaction force applied to the plate 8 by the robot arm 200B when the above force is applied.
The controller controls the reaction force to increase in proportion to the displacement until the displacement reaches a predetermined X mm. The controller controls so that the reaction force becomes constant when the displacement exceeds a predetermined X mm.

By controlling in this way, when a force is applied to the plate 8, the reaction force initially increases in proportion to the displacement, so that a person who touches the plate 8 feels that it is a hard surface. When the displacement exceeds a predetermined X mm, the reaction force becomes constant, so that a person who touches the plate 8 feels a soft surface.

(Effect of Fourth Embodiment)
According to the mesh robot 300 of the present embodiment, an ultra-small mesh-like surface capable of deforming a plurality of plates 8 into an arbitrary position / posture by a robot arm 200 equipped with an ultrasonic motor 100 which is ultra-small and has a large output torque. Can be realized.

According to the mesh robot 300 of the present embodiment, the surface 8a created by the surfaces 8a of the plurality of plates 8 is hard and soft by controlling the robot arm 200 equipped with the ultrasonic motor 100 having high low speed, high torque, and high responsiveness. Can be controlled. By using the compliance control, the mesh robot 300 can be used as a shape presenting device that can reproduce an arbitrary shape and can also reproduce the hardness and softness of the surface thereof.

(Modification example)
Although the fourth embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like within a range that does not deviate from the gist of the present invention. .. In addition, the components shown in the fourth embodiment described above and the modified examples shown below can be appropriately combined and configured.

For example, in the above embodiment, the plate 8 is composed of four divided plates 80, but the structure of the plate is not limited to this. For example, the plate may be composed of a single flexible disc member. The plate may have any configuration as long as it is flexible and can absorb control errors in the posture and position of the robot arm 200B.

Further, in the above embodiment, the mesh robot 300 is configured by arranging 25 plates 8 in a grid pattern, but the configuration of the mesh robot is not limited to this. For example, a plurality of plates 8 may be arranged in a circular shape, or may be arranged in an annular shape. Regardless of how the plurality of plates 8 are arranged, the mesh robot 300 can be configured by connecting the adjacent plates 8 with the robot arm 200B.

The present invention can be applied to ultrasonic motors, robot arms, and mesh robots.

1 Stator 10 Inner peripheral surface 11 First inner peripheral surface 12 Second inner peripheral surface 2 Piezoelectric element (ultrasonic wave generating element)
3 Rotor shafts 31, 31B First shaft 31a Base end opening (first opening)
31b Tip opening 31c First locking hole 31d First engaging portion 31e First convex portion 32 Second shaft 32a Base end opening (second opening)
32b Tip opening 32c Second locking hole 32d Second engaging portion 32e Second convex portion 4, 4B Spring fixing member 41 First spring fixing member 42 Second spring fixing member 5, 5B Spring (elastic member)
7 Connecting member 8 Plate 8a Plate front surface 8b Plate back surface 80 Divided plate 81 Recess 100, 100B Ultrasonic motor 200, 200B Robot arm 300 Mesh robot

Claims (9)

A rotor shaft having a cylindrical first shaft and a cylindrical second shaft,
An elastic member that applies a force in a direction that brings the first opening, which is the opening on the base end side of the first shaft, and the second opening, which is the opening on the base end side of the second shaft, closer to each other.
A stator that is rectangular parallelepiped and has a through hole through which the rotor shaft penetrates.
The ultrasonic wave generating element attached to the outer surface of the stator and
With
The first shaft and the second shaft are provided so that the first opening and the second opening face each other.
The inner peripheral surface of the stator is tapered.
The first shaft has a first engaging portion processed into a tapered shape on the outer circumference on the base end side.
The second shaft has a second engaging portion processed into a tapered shape on the outer circumference on the base end side.
The inner peripheral surface of the stator is engaged with the first engaging portion and the second engaging portion.
Ultrasonic motor. The first engaging portion is processed into a tapered shape so that the diameter dimension becomes smaller toward the first opening.
The second engaging portion is processed into a tapered shape so that the diameter dimension becomes smaller toward the second opening.
The ultrasonic motor according to claim 1. The first shaft has a first convex portion protruding in the longitudinal axis direction in the first opening.
The second shaft has a second convex portion protruding in the longitudinal axis direction in the second opening.
When the first shaft and the second shaft rotate with the longitudinal axis direction as the rotation axis, at least one end of both ends in the rotation direction engages.
The ultrasonic motor according to claim 1 or 2. A plurality of grooves are formed on the inner peripheral surface of the stator along the longitudinal direction.
The ultrasonic motor according to any one of claims 1 to 3. A first spring fixing member to which one end of the elastic member is attached and locked to the first shaft,
Further comprising a second spring fixing member to which the other end of the elastic member is attached and locked to the second shaft.
The first spring fixing member is locked at any one of a plurality of positions of the first shaft.
The ultrasonic motor according to any one of claims 1 to 4. The ultrasonic motor according to any one of claims 1 to 5 is provided.
A robot arm including a connecting member for connecting the ultrasonic motors. Having a plurality of robot arms according to claim 6,
A flexible plate to which the plurality of robot arms are connected,
A mesh robot equipped with. The plate is composed of four divided plates.
One robot arm is connected to each of the four dividing plates.
The mesh robot according to claim 7. A reaction force is generated in proportion to the external force until the displacement of the plate due to the external force reaches a predetermined value.
When the displacement exceeds the predetermined value, the reaction force becomes constant.
The mesh robot according to claim 7 or 8.

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