1. Technical Field
The present invention relates to motors, robot hands, and robots.
2. Related Art
As a motor driving a driven body by the vibration of a piezoelectric element, a motor that drives a driven body by making a protrusion of a reinforcing plate come into contact with the driven body in an actuator formed of the reinforcing plate having the protrusion integrally formed therein, the reinforcing plate on which a rectangular flat plate-like piezoelectric element is stacked, is known (JP-A-2010-233335 (Patent Document 1)). The motor provided with a piezoelectric actuator includes a biasing unit for making the protrusion of the reinforcing plate of the piezoelectric actuator come into contact with the driven body, and a frictional force developed between the protrusion of the reinforcing plate and the driven unit by a biasing force generated by the biasing unit transfers the vibration of the protrusion of the reinforcing plate to the driven unit and drives the driven unit in a predetermined direction.
However, in Patent Document 1 described above, the direction in which the piezoelectric actuator is biased by the biasing unit toward the driven body is biased along a vibrating surface of planar vibration in the reinforcing plate toward the driving center of the driven body. In such a motor, depending on the deflection of the driven body rotatably secured to an apparatus main body and the amount of backlash of the piezoelectric actuator slidably secured to the apparatus main body, a relative slippage (slip) occurs in a region of contact between the driven body and the protrusion of the piezoelectric actuator in a direction intersecting with the biasing direction. This slippage (slip) greatly reduces the efficiency of transfer of the vibration of the piezoelectric actuator to the driven body.
An advantage of some aspects of the invention is to provide a motor that prevents a slip between an actuator and a driven body in a region of contact between the driven body and a protrusion of a piezoelectric actuator, the slip caused by a relative slippage in a direction intersecting with a biasing direction, and transfers the vibration of the piezoelectric actuator to the driven body efficiently and a robot hand and a robot that use such a motor.
This application example is directed to a motor including: a driven unit; an actuator including a vibrating plate having, at an end thereof, a protrusion which is biased toward the driven unit and a piezoelectric body stacked on the vibrating plate; and a biasing unit biasing the actuator toward the driven unit, wherein a direction in which the biasing unit biases the actuator toward the driven unit intersects with a vibrating surface of the vibrating plate.
According to the application example described above, by disposing the biasing unit biasing the actuator toward the driven unit in such a way that the biasing unit biases the actuator toward the driven unit in a direction intersecting with the vibrating surface of the vibrating plate which is excited by the piezoelectric body included in the actuator, a biasing force biasing the actuator toward the driven unit along the vibrating surface of the vibrating plate and a biasing force biasing the actuator in the direction intersecting with the vibrating surface of the vibrating plate are applied to the actuator. Of these biasing forces, by the biasing force biasing the actuator in the direction intersecting with the vibrating surface of the vibrating plate, the driven unit which makes contact with the actuator is also biased in the direction intersecting with the vibrating surface of the vibrating plate of the actuator. As a result, deflection and backlash due to a clearance between the parts in a driving portion provided to make it possible to drive the driven unit and deflection and backlash due to a clearance between the parts in a sliding portion provided to allow the actuator to slide on a motor base are moved to one side in a predetermined direction by the biasing force biasing the actuator in the direction intersecting with the vibrating surface of the vibrating plate, making it possible to prevent deflection and backlash when the driven unit is driven. This makes it possible to prevent a transfer loss of the vibration of the actuator and obtain a motor that can drive the driven unit efficiently.
This application example is directed to the motor of the application example described above, wherein an angle θ at which the direction in which the biasing unit biases the actuator toward the driven unit intersects with the vibrating surface may satisfy 0<θ≦30°.
According to the application example described above, it is possible to obtain an efficient motor with a small transfer loss of the vibration of the actuator, the motor in which a transfer loss of vibration due to frictional resistance in a portion in which the actuator slides on the motor base is reduced, deflection and backlash in the actuator and the driven unit are moved to one side in a predetermined direction by the biasing force biasing the actuator in the direction intersecting with the vibrating surface of the vibrating plate, and deflection and backlash are prevented when the driven unit is driven.
This application example is directed to the motor of the application example described above, wherein a regulating unit regulating the actuator in a direction intersecting with the vibrating surface may be provided.
According to the application example described above, it is possible to prevent the actuator from being excessively moved to one side in a predetermined direction by the biasing force biasing the actuator in the direction intersecting with the vibrating surface of the vibrating plate. This makes it possible to ensure contact between the driven unit and the actuator.
This application example is directed to a robot hand including the motor of the application example described above.
The robot hand of this application example can be made compact and lightweight while having a high degree of flexibility and a large number of motors.
This application example is directed to a robot including the robot hand of the application example described above.
The robot of this application example is highly versatile and can perform assembly, inspections, etc. of a sophisticated electronic apparatus.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Hereinafter, embodiments according to the invention will be described with reference to the drawings.
Moreover, the actuator 30 is formed of piezoelectric elements 32 and 33, each being a rectangular piezoelectric body in which an electrode is formed, and a vibrating plate 31, the piezoelectric elements 32 and 33 bonded together in such a way as to sandwich the vibrating plate 31. Examples of the piezoelectric elements 32 and 33 are piezoelectric materials such as lead zirconate titanate (PZT:Pb(Zr,Ti)O3), crystal, and lithium niobate (LiNbO3); in particular, PZT is suitably used. Furthermore, the electrode to be formed can be formed by forming a film of conductive metal such as Au, Ti, or Ag by vapor deposition, sputtering, or the like. As the actuator 30, the vibrating plate 31 has, at an end thereof, a projection 31a that is secured to the support 40, biased by the coil spring 60 toward the driven body 20, and brought into contact with the driven body 20. Incidentally, the vibrating plate 31 is formed of stainless steel, nickel, rubber metal, or the like, and stainless steel is suitably used because the stainless steel can be processed easily. The actuator 30 is secured to the support 40 with screws 51 that are placed through holes 31c of mounting sections 31b formed in the vibrating plate 31 for mounting on the support 40 and are fitted into screw holes 40b of fixing sections 40a formed in the support 40.
The support 40 is slidably secured to the base 10 as a result of securing a fixing pin 70 placed through a guide hole 40c of the support 40 to the base 10. At an end of the support 40 opposite to the driven body 20, a spring mounting section 40e having a biased surface 40d on which the coil spring 60 as the biasing unit is placed, the biased surface 40d biased by the coil spring 60, is provided. The coil spring 60 placed in the spring mounting section 40e is held, at one end thereof, by a spring holding section 11 of the base 10, and biases the spring mounting section 40e, that is, the support 40 toward the driven body 20 by the deflection of the coil spring 60.
As shown in
Moreover, the base 10 has spring supporting sections 12 to which leaf springs 80 as a regulating unit for the support 40, which will be described later, are secured, and the leaf springs 80 are secured to the spring supporting sections 12 with screws 52 that are placed through holes 80a of the leaf springs 80 and are fitted into screw holes 12a of the spring supporting sections 12.
The driven body 20 is rotatably secured to the base as a result of attaching a rotating shaft 21 to an unillustrated bearing of the base 10. The driving (rotation) of the driven body 20 is adjusted to a desired rotation speed or to produce desired output torque via a reduction or speed increasing gear 200 connected to the rotating shaft 21 to drive a driven apparatus.
A section taken on the line A-A′ shown in
The base 10 has, on a side 10b thereof where the actuator 30 is mounted, a rail 10a formed as a protrusion for reducing the range of contact between the base 10 and the support 40 to allow the support 40 to slide on the base 10 more smoothly. In this embodiment, as the rail 10a, two rails 10a are formed in the direction in which the coil spring 60 biases the support 40, but the invention is not limited thereto. There may be one rail 10a or three or more rails 10a. Since the rail 10a formed in this manner may allow the support 40 to move toward the base 10, the support 40 can also be mounted in such a way that the tips of springs 81 are close to sides 40g (hereinafter referred to as back sides 40g) opposite to the front sides 40f as shown in
Moreover, as shown in
Next, the operation of the actuator 30 will be described by using
Moreover, as shown in
The elliptic orbits R1 and R2 of the projection 31a generated by the above-described vibration of the actuator 30 make contact with the driven body 20 by being biased by the biasing force, and drive the driven body 20 in the directions of arrows r1 and r2 shown in the drawings. In the motor 100 which is driven in this manner, to secure the driven body 20 to the base 10 in such a way that the driven body 20 can rotate, a predetermined clearance or the like is created between the unillustrated bearing and the rotating shaft 21. Moreover, the support 40 which is slidably secured to the base 10 is also secured to the base 10 in such a way that the support 40 can slide on the base 10 by an appropriate clearance created between a mounting section for the support 40, the mounting section formed of the rail 10a provided on the base 10 and the fixing pin 70, and the support 40. This induces deflection or backlash behaviors of the driven body 20 and the actuator 30 secured to the support 40.
Even when there are factors inducing the deflection or backlash in the driven body 20 and the actuator 30, by mounting the coil spring 60 which is the biasing unit in the motor 100 at an angle θ as shown in
In this state, since the biasing force F1 is made to act at all times by the coil spring 60, the driven body 20 is driven in a state in which the projection 31a and the portion of the driven body 20 with which the projection 31a makes contact are always pushed upward in the drawing. In other words, in this state, the driven body 20 is driven with the state shown in
To prevent the projection 31a of the actuator 30 from being pushed upward excessively in the state shown in
As described above, in the motor 100 according to this embodiment, even when a predetermined clearance is created between the driven body 20 which is a movable element and the base 10 and between the support 40 which is a movable element and the base 10 to move the driven body 20 and the support 40 with respect to the base 10 and this clearance causes deflection or backlash, by always biasing the driven body 20 and the support 40 in a given direction by mounting the coil spring 60 as the biasing unit in such a way as to form a predetermined angle θ with respect to the direction in which the actuator 30 is biased, it is possible to prevent a slip in a region of contact between the projection 31a of the actuator 30 and the driven body 20, the region of contact that is irrelevant to the driving, and convert the vibration of the actuator 30 efficiently into the driving force to drive the driven body 20.
The arm section 2200 is formed of a first frame 2210, a second frame 2220, a third frame 2230, a fourth frame 2240, and a fifth frame 2250. The first frame 2210 is connected to the main body section 2100 by a rotating and bending shaft in such a way as to be able to rotate or bend. The second frame 2220 is connected to the first frame 2210 and the third frame 2230 by rotating and bending shafts. The third frame 2230 is connected to the second frame 2220 and the fourth frame 2240 by rotating and bending shafts. The fourth frame 2240 is connected to the third frame 2230 and the fifth frame 2250 by rotating and bending shafts. The fifth frame 2250 is connected to the fourth frame 2240 by a rotating and bending shaft. The arm section 2200 is controlled by the control unit so that the frames 2210 to 2250 move in a coordinated fashion while rotating or bending about the rotating and bending shafts.
To an end of the fifth frame 2250 of the arm section 2200, the end opposite to the end to which the fourth frame 2240 is connected, a robot hand connection 2300 is connected, and the robot hand 1000 is attached to the robot hand connection 2300. The motor 100 that rotates the robot hand 1000 is built into the robot hand connection 2300, and the robot hand 1000 can grip an object. By using the compact and lightweight robot hand 1000, it is possible to provide a robot that is highly versatile and can perform assembly, inspections, etc. of a sophisticated electronic apparatus.
The entire disclosure of Japanese Patent Application No. 2011-102756, filed May 2, 2011 is expressly incorporated by reference herein.
Number | Date | Country | Kind |
---|---|---|---|
2011-102756 | May 2011 | JP | national |