JPH05318373A - Micro hand mechanism - Google Patents

Abstract

PURPOSE:To move a micro hand used for assembling of optical elements, optical parts, etc. with the simple and inexpensive structure and relatively low voltage in a large movable range. CONSTITUTION:On a peripheral face of a rod-state member 1 made of an elastic body, a thin plate-state piezoelectric element (bimorph) 5 made of a polymer piezoelectric material and a piezoelectric actuator 2 provided with an electrode 6 for applying a voltage to this thin plate-state piezoelectric element totally or partially are provided. When the voltage is applied, the piezoelectric actuator 2 is bent, resulting in deformation of the rod-state member 1. A micro part such as an optical part is held by a plurality of the rod-state members 1 to carry out connection, assembling, etc. By changing arrangement pattern or arrangement number of the piezoelectric actuator, electrode pattern or electrode applying pattern, movement with much freedom can be obtained. The actuator itself is soft and can softly holds breakable parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro hand mechanism as an end effector in an assembly robot used in an automatic assembly line for minute parts such as optical communication components.

[0002]

2. Description of the Related Art At present, in the field of optical communication, it is necessary to produce optical devices, optical components, optical modules, etc. at low cost and with high reliability in order to construct an optical communication system. Therefore, there is a demand for automation of production of these optical products. However, these parts are
As shown in (1), it is very small compared to electronic parts (for example, optical fiber has a diameter of 125 μm), and most of them are made of glass or plastic, so they are easily scratched. Therefore, the assembling robot currently used for assembling electronic parts (milli-order size) cannot be used as it is for assembling optical parts.

For this reason, at present, assembling of fragile microscopic objects such as optical parts such as optical fibers and optical filters is performed manually. However, since the manual method is a fine and tedious task, it is required to develop a hand for an automatic assembly robot that can handle these minute optical components softly. Has been made.

[0004]

[Table 1]

Conventional Example 1 [Yasuda et al .: Research on Comb-type Electrostatic Micro Actuator, Robotics Mechatronics Lecture Meeting of the Japan Society of Mechanical Engineers 91 (1991)] As shown in FIG. 10, an integrated circuit manufacturing process is applied. , The comb electrode 50, the spring portion 51, and the arm portion 52 are formed, and the arm portion 5 is formed by the electrostatic attraction P of the comb electrode 50 portion.
It is based on the principle of moving the second tip grip portion 53. Two parts of these members are combined to form a gripper that grips the component.

Conventional example 2 [Fukuda et al., 2 persons: Control of micromanipulator, The Japan Society of Mechanical Engineers, C edition, 53-493
(1987)] This is a combination of two parts of a structure including an electrode 60 and an arm 61 as shown in FIG. 11, and has a shape in which electrodes are formed in parallel. This is the principle of moving the tip portion of the arm 61 by the electrostatic attraction between the two electrodes.

Conventional Example 3 [Suzumori et al .: Robot drive mechanism using flexible microactuator,
Proceedings of the Japan Society of Mechanical Engineers No.910-37 Symposium (199
1)] As shown in FIG. 12, in a fluid type actuator utilizing elastic deformation of fiber reinforced rubber, three pressure chambers 70a, 70b, 70c are formed in a cylindrical main body 70, and caps 71, 72 are provided at both ends. It is a structure in which the main body 70 is elastically deformed by closing and supplying air to the pressure chambers 70a to 70c through the three tubes 73 to 75. The main body 70 is made of rubber 70e reinforced with reinforcing fibers 70d.

[0008]

However, in the electrostatic actuators of Conventional Examples 1 and 2, the movable range is narrow (up to several tens of μm), and a high voltage (several hundreds to thousands of V) is used to drive the actuator. There is a problem you need. In the case of the pneumatic control type actuator of Conventional Example 3, since the pneumatic pressure is used, the response speed cannot be made high (millisecond order),
There are problems such as the need for special equipment such as valves and air pressure sources. In other words, the movable range required for the actuators that compose the hand for operations such as grasping, connecting, and assembling optical components is several, considering the size of the optical components and the mounting density when they are assembled. About 100 μm is necessary. The electrostatic types of Conventional Examples 1 and 2 are insufficient to satisfy this use. Also, in the pneumatic control type, the response speed is slow, so that the cycle time becomes long, which affects productivity, and the need for special devices such as valves and pneumatic sources makes the device itself expensive. Will end up.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to perform a work such as gripping and connecting a minute component such as an optical communication component relatively easily and inexpensively. According to the present invention, a micro hand mechanism that can be performed with a relatively low voltage and a relatively large movable range is provided.

[0010]

In order to achieve the above object, the present invention has the following constitution. That is, the micro hand mechanism of the present invention comprises a thin plate piezoelectric element made of a polymeric piezoelectric material on the peripheral surface of a rod-shaped member made of an elastic body,
This thin plate piezoelectric element is characterized by being provided with a piezoelectric actuator provided with an electrode for applying a voltage entirely or partially. The rod-shaped member constitutes a finger of a micro hand, and may be solid or hollow, but is a solid cylindrical member made of rubber. As the thin plate piezoelectric element, a bimorph type or monomorph type piezoelectric element made of a polymer such as polyvinylidene fluoride is used. The electrodes are wholly bonded or partially provided on the surface of the piezoelectric bimorph or the like so that the electrodes of each part can be independently controlled.

[0011]

When a voltage is applied to the electrodes of the piezoelectric actuator, the thin plate piezoelectric element bends due to expansion and contraction in the longitudinal direction due to the inverse piezoelectric effect, and as a result, the cantilevered rod-shaped member bends. By disposing at least one pair of such rod-shaped members, the grasped micro component can be moved. In the case of the piezoelectric bimorph, a displacement amount of several tens to several hundreds μm can be obtained with an applied voltage of several hundred V, and a large movable range can be obtained with a low voltage as compared with an electrostatic actuator. Also, the arrangement pattern of the piezoelectric actuator
By varying the number of arrangements, the electrode pattern, the electrode application pattern, and the like, it is possible to obtain movement with multiple degrees of freedom. By using a polymer piezoelectric material for the piezoelectric element,
Since the actuator itself is soft, fragile objects such as optical parts can be softly gripped without damaging them.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on illustrated embodiments. 1 to 3 show a first embodiment of a microactuator according to the present invention, and FIGS. 5 to 7 show
FIG. 8 shows a second embodiment of a microactuator in which the arrangement of piezoelectric elements / electrodes is changed. FIG. 8 shows a specific example in which the microactuator is attached to the tip of a manipulator to grip an optical component and perform operations such as movement and assembly. Show.

Example 1 As shown in FIG. 1, a solid cylindrical member 1 made of a rubber elastic body and having a diameter of several mm has a width of several tenths of a mm and a thickness of 100 minutes. The thin piezoelectric piezoelectric bimorphs 2, 3 and 4 of several mm are attached to form one finger of the micro hand. Piezoelectric bimorph
Two piezoelectric elements (electrostrictive elements) with electrodes on the surface are laminated, voltage is applied to one piezoelectric element so that the element extends in the longitudinal direction, and voltage is applied to the other piezoelectric element so that the element contracts. , Or a piezoelectric actuator in which a large bending displacement is obtained by joining two piezoelectric materials having different compositions. In the present invention, the piezoelectric element is made of polyvinylidene fluoride (PVDF), vinylidene fluoride, and trifluoroethylene. Piezoelectric elements made of polymer piezoelectric materials such as polymers are used so that fragile minute parts can be handled.

The piezoelectric bimorphs 2 to 4 are arranged such that their longitudinal directions are parallel to the center line of the columnar member 1 and at intervals of 120 ° in the circumferential direction of the columnar member 1. Attach to the outer peripheral surface of the columnar member with an adhesive or the like. If the electrode 6 is, for example, a two-layer laminated type piezoelectric bimorph, as shown in FIG. 2, it is arranged on the front surface and the back surface and in the middle of the two polymer piezoelectric elements 5, and each of the electrodes 6a to 6c has each polymer. The power source 7 is connected so that the piezoelectric elements 5a and 5b respectively expand and contract. When a voltage is applied, the polymer piezoelectric elements 5a and 5b respectively expand and contract, the piezoelectric bimorph itself bends, and as a result, the columnar member 1 bends. By applying a positive voltage or a negative voltage to the electrodes 6a and 6b, the bending direction of the columnar member 1 can be changed. By selectively operating each of the piezoelectric bimorphs 2 to 4 or controlling the applied voltage and changing the direction of the applied voltage, the columnar member 1 can be displaced in various directions by various displacement amounts.

As shown in FIG. 3, the piezoelectric bimorph 2,
Assuming that the forces generated by 3 and 4 are F ₁ , F _{2 and} F ₃ , respectively, the tip of the elastic columnar member 1 is displaced in the direction of the angle θ by the resultant force F. Hereinafter, in the analysis of the voltage-displacement amount characteristic, the following symbols will be used. Regarding the flat plate-shaped piezoelectric bimorph, the width is W, the length is L, the thickness of one piezoelectric film is t, and the piezoelectric constant d ₃₁
(D _ij : i is the displacement direction, j is the voltage direction, 3 is the plate pressure direction,
1 and 2 are in-plane directions). The elastic columnar member 1 has a length L, a diameter d, and a Young's modulus E. The voltages applied to the respective piezoelectric bimorphs are V ₁ , V ₂ and V ₃ .

The relationship between the resultant force F and the displacement amount U of the elastic cylindrical member 1 is expressed by the equation (2). Further, the displacement direction θ is given by the equation (3).

[0017]

[Equation 1]

[0018]

[Equation 2]

[0019]

[Equation 3]

FIG. 4 shows the numerical calculation results when the voltage is applied to only one piezoelectric bimorph in the actuator having the shape and material as shown in Table 2. From this figure, it is understood that a displacement amount of several tens to several hundreds of μm can be obtained by changing the voltage applied to the piezoelectric bimorph. In addition, it was found that the analysis results shown here and the data obtained by the experiment agree relatively well. Furthermore, as a result of observing the operation of the actuator using a CCD camera and a VTR, it was confirmed that this actuator is actually operating.

[0021]

[Table 2]

[Embodiment 2] As shown in FIG.
In the actuator in which three thin plate piezoelectric bimorphs 2 to 4 are attached to the outer peripheral surface of the elastic columnar member 1 shown in the above-described first embodiment at intervals of 120 °, the electrode portion attached to each piezoelectric bimorph 2 to 4. Is divided into two in the axial direction of the cylindrical member 1. That is, as shown in FIG. 6, only the electrode portion of each piezoelectric bimorph 2-4 is divided into two, and the piezoelectric bimorphs 2-4 themselves are divided into two,
A power source 7 is attached to each of the divided electrodes 6 so that a voltage is applied to each electrode independently. As a result, the bimorph composed of the respective electrode portions has a bending moment M
As a result, it is bent and deformed, and as a whole is flexibly deformed. For the electrodes 6-1 and 6-2 of each piezoelectric bimorph 2 to 4,
By independently applying the voltage, the degree of freedom of the entire actuator can be increased. The operation example will be described below.

In the piezoelectric actuators used shown in Table 3, when a voltage of 100 V is applied only to the electrode 6-1 of the piezoelectric bimorph 2, the actuator has a shape in which only the tip portion bends as shown in FIG. The tip displacement at this time is 25 μm. Also, as in the case of Example 1, the agreement between the calculation result and the experimental data and the actual operation could be confirmed.

[0024]

[Table 3]

[Application Example] As shown in FIG. 8, this is an example applied to a micro hand in the handling of an optical component, and is a grip type hand in which two single fingers described in the first embodiment are combined. This hand is attached to the tip of a robot arm (manipulator), and is constructed by attaching a base of a pair of fingers 11 to a fixing jig 10. This finger 11 is provided with the piezoelectric bimorphs 2 to 4 around the elastic cylindrical member 1 as in FIG. FIG. 9 shows an optical filter W using such a hand.
This is an example of an experiment in which the piezoelectric bimorphs 2L and 2R are applied (2L and 2R).
It is confirmed that the optical filter W is moved by 55 μm in the X-axis direction.

In the present invention, the number of electrodes, the electrode interval, the electrode arrangement, etc. described in the first and second embodiments, the arrangement pattern, the number of arrangements of the piezoelectric bimorph, etc. are further limited to the number of fingers described in the application example. However, various modifications are possible without departing from the scope of the invention, and these modifications are not excluded from the scope of the invention. Further, although the bimorph type piezoelectric element has been described, a monomorph type piezoelectric actuator that causes bending due to a partial difference in strain of the single plate piezoelectric element can also be used.

[0027]

As described above, according to the present invention, a rod-shaped member made of an elastic material is provided with a piezoelectric actuator made of a piezoelectric element made of a polymeric piezoelectric material and electrodes for applying a voltage, and the rod-shaped member is moved by displacement of the piezoelectric actuator. Since it is deformed, the following effects are obtained. (1) Compared with the conventional electrostatic actuator, it is possible to obtain a large displacement at a low voltage, and a relatively simple and inexpensive mechanism provides a micro component such as an optical communication component (up to several hundred μm). It can fully handle work such as gripping, connecting, and assembling. (2) By varying the arrangement pattern / number of piezoelectric actuators, electrode patterns, electrode application patterns, etc., it is possible to obtain movements with multiple degrees of freedom. It is suitable for handling a component of several hundreds of μm. For example, it can be used for positioning and connecting optical fibers and optical waveguides, and is useful for future optical interconnection technology. (3) Since the piezoelectric element is made of a polymeric piezoelectric material and the actuator itself is soft, it is possible to grasp soft materials such as optical parts without damaging them. (4) Since it has a simple structure in which the piezoelectric element is attached to the rod-shaped member and does not require force control, it is possible to provide an inexpensive optical component automatic assembly apparatus as a whole.

[Brief description of drawings]

FIG. 1 is a perspective view showing a micro hand mechanism of the present invention.

FIG. 2 is a partial cross-sectional view of FIG.

FIG. 3 shows an operating state of the micro hand of FIG.
(A) is a schematic front view and (b) is a schematic side view.

4 is a graph showing applied voltage-tip displacement amount characteristics in the micro hand of FIG. 1. FIG.

FIG. 5 is a perspective view showing a modified example of FIG.

6 shows a piezoelectric actuator of the micro hand of FIG. 5, (a) is a schematic plan view, (b) is a schematic side view,
(C) is a partial enlarged sectional view.

7 is a perspective view showing an operating state of the micro hand of FIG. 1. FIG.

FIG. 8 is a perspective view showing an example in which the present invention is applied to a gripper type hand.

FIG. 9 is a schematic diagram showing the operating states of FIG. 8 in order.

FIG. 10 is a schematic view showing a conventional electrostatic actuator.

FIG. 11 is a schematic view showing another conventional electrostatic actuator.

FIG. 12 is a schematic view showing a conventional pneumatic actuator.

[Explanation of symbols]

 1 Elastic Rod Member (Cylindrical Member) 2, 3, 4 Piezoelectric Actuator (Bimorph) 5 Polymer Piezoelectric Element 6 Electrode 7 Power Supply 10 Fixing Tool 11 Finger

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B25J 19/00 A 8611-3F H01L 41/09 41/08 H02N 2/00 B 8525-5H

Claims (1)

[Claims] 1. A thin plate piezoelectric element made of a polymeric piezoelectric material and an electrode for applying a voltage to the thin plate piezoelectric element wholly or partially on the peripheral surface of a rod-shaped member made of an elastic material. A micro hand mechanism comprising a piezoelectric actuator.