JP2000158365A - Magnetic levitation type micro-hand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable three dimensional parallel movement in a microminiature. SOLUTION: This magnetic levitation type micro-hand is provided with magnetic actuators 1, 4, 7 consisting of a movable piece consisting of permanet magnets 3, 6, 9 arranged so as to be driven in three dimensional parallel and a stator having magnetized coils 2, 5, 8 fixed on the fixing part, a body 10 driven by these magnetic actuators 1, 4, 7, laser displacement sensors 11, 12, 13 for detecting the displacement of this driven body 10, a parallel link mechanism 14 combined with the driven body and an endeffector combined with this parallel link mechanism 14 and the adapter 15 for installing a balance weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation type microhand used for machining and assembly.

[0002]

2. Description of the Prior Art The fabrication and processing of small parts is required to manufacture micromachines. Since various micromechanical components such as microsensors and actuators have been developed in recent years, the demand for manufacturing means thereof has been increasing.

[0003] Conventional commercially available micromanipulators are:
Suction, cutting and drawing operations can be performed. While such work is sufficient for industrial inspection and biotechnology, the manufacture of micromachines requires other work.

[0004] Micromachines are sometimes part of macromachines, and their manufacturing process takes place in tight spaces. Therefore, it is desirable that the manufacturing apparatus has a small size.

[0005] Under such circumstances, it is impossible to adopt a conventional machine tool or industrial robot.

[0006]

As described above, conventional micromanipulators are insufficient for manufacturing micromachines. That is, the ability to machine as well as assemble is required in manufacturing micromachines.

The present invention has been made in view of the above circumstances, and has as its object to provide an ultra-compact, magnetically levitated microhand capable of three-dimensional parallel operation.

[0008]

According to the present invention, there is provided a magnetic levitation type micro-hand which is arranged so as to be capable of three-dimensional parallel drive, and is movable by a permanent magnet. A magnetic actuator including a stator and a stator having an excitation coil fixed to a fixed portion; a driven body driven by the magnetic actuator; a displacement sensor for detecting a displacement of the driven body; A parallel link mechanism coupled to a body, and an end effector attached to an end of the driven body or the parallel link mechanism are provided.

[2] In the magnetic levitation type micro-hand described in the above [1], the magnetic actuator has a stator composed of a cylindrical excitation coil and a movable element composed of a permanent magnet.

[3] In the magnetic levitation type microhand described in the above [1], the displacement sensor has a resolution of the order of 1 μm or more.

[4] In the magnetic levitation type microhand described in the above [1], the parallel link mechanism moves in a parallelogram manner, and always keeps balance with gravity.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a magnetic levitation type micro hand showing an embodiment of the present invention.

As shown in FIG. 1, the magnetic levitation type micro hand comprises a driven body 10, parallel link mechanisms 14, 16, 17, and 18 for connecting an end effector, and rare earth permanent magnets 3, 6, and 9. Mover, excitation coil 2,
Magnetic actuators 1, 4, 7 having stators 5, 8, and laser displacement sensors 11, 12, 13;
It is composed of an adapter (an adapter for mounting a counterweight) for mounting a weight (not shown) for maintaining balance against gravity (the end effector is preferably mounted on the driven body 10 in terms of accuracy, but the adapter 15 It is also possible to mount it on.)

The excitation coils 2, 5, 8 of the magnetic actuators 1, 4, 7 and the laser displacement sensors 11, 1
2 and 13 are fixed to a fixing portion (not shown).

More specifically, the magnetic actuator 1 for driving the driven body 10 in the X-axis direction, the magnetic actuator 4 for driving the driven body 10 in the Y-axis direction, the magnetic actuator 7 for driving the driven body 10 in the Z-axis direction, A laser displacement sensor 11 for detecting the movement of the driven body 10 in the X-axis direction;
Laser displacement sensor 1 for detecting movement in the Y-axis direction of 0
2. Using the laser displacement sensor 13 for detecting the movement of the driven body 10 in the Z-axis direction, the driven body 10 and the adapter 15 for mounting the counterweight are symmetrically moved via the first parallel link mechanism 14. Then, the end effector can be driven. In addition,
In FIG. 1, 21 is a fixed base, 22 is a first parallel link mechanism mounting portion, 23, 25, 27, and 28 are rotation axes, 24 is an upper side link, and 26 is a bottom side link.

The magnetic levitation type micro hand is improved in the following points as compared with the conventional one.

(1) Fix the direction of the end effector,
A parallel link mechanism 14 for performing parallel movement in the X, Y, and Z axis directions is employed. Conventionally, a lever mechanism has been used.

(2) Magnetic actuator 1 composed of rare earth permanent magnets 3, 6, 9 and exciting coils 2, 5, 8
Nos. 4 and 7 were designed so that the driving action, which is characterized by linearity, makes a large stroke. This principle is similar to a voice coil motor. Heretofore, a pair of electromagnets has been used.

(3) High-precision laser displacement sensors 11, 12, and 13 having a resolution of 1 μm are used. Conventionally, an eddy current sensor has been used.

Hereinafter, each part of the magnetic levitation type micro hand will be described in detail.

[1] First, the parallel link mechanism will be described.

FIG. 2 is a schematic view of a parallel link mechanism of a magnetic levitation type micro hand showing an embodiment of the present invention.

Here, two parallel link mechanisms will be described.

The conventional lever mechanism has a simple structure and is easily balanced with gravity. The tasks to be performed include micro-drawing with one finger, and selecting an object with two fingers. These tasks can be performed using the tip of the finger.

However, operations such as machining are
Performed using the side of the tool, requires a certain direction of the end effector.

Therefore, in the present invention, as shown in FIG. 2, a micro hand of a type in which the end effector 31 is connected to the parallel link mechanism is employed.

There are several problems in studying the mechanism design.

First, in the direct driving operation of the driven body 10, there is a point that the magnetic force is relatively small, and a structure balanced with gravity is required. Since many links are used, the link and the counterweight tend to interfere with each other.

Second, considering the transmission efficiency of the force driven by the magnet, it is desirable to use a parallelogram having a shape close to a square as shown in FIG. In FIG. 3, F is a driving force, and Fe is a force component effective for movement.

Third, it is desirable to use long links to reduce the friction effect in the bearing.

In a simple design, there are three parallelograms connected in series corresponding to the x, y and z movements. However, this design requires three counterweights. Therefore, the mechanism is complicated and large. Therefore, according to the present invention, a link mechanism combining two parallelograms is connected in series to another parallel link mechanism as shown in FIG.
However, since interference remains between the two link mechanisms,
Connected at intervals. This design can be perfectly gravitationally balanced, the microhand can be used in any arrangement, and can be mounted on a conventional manipulator.

FIG. 4 shows the size of this mechanism. In FIG. 4, portions equivalent to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In this figure, the length of the link is 100 mm, and the influence by the bearing friction is negligible compared to the magnetic force. The use of an aluminum alloy as the material of the link makes it possible to reduce the inertia and exert better controllability. In FIG. 4, reference numeral 32 denotes a working range by this mechanism, 33 denotes a sensor,
The actuator, the end effector mounting portion, and D indicate the intervals.

[2] Magnetic Actuator There are two types of magnetic actuators:
One is a pair of electromagnets used in magnetic bearings,
One is a permanent magnet and a coil. Let's compare these two types. Assuming that the same coil is used, FIG.
The former type shown in FIG.
The latter type shown in FIG. 5B includes a permanent magnet 37 connected to the object 34. S [m ² ], I [A] and n
[/ M] is the number of turns per unit of cross section area, current, and coil length. Then, the magnetic field H becomes: H = nI (1) Estimate the maximum force of both types. Assume that the former type of interval is very small. Then, the magnetic force F can be expressed as follows.

F = ² μH ² S (2) Here, μ represents the magnetic permeability of the object.

Next, the latter type will be examined. The cross section of the permanent magnet is circular with an area S _p, magnetic poles is in a coil. Then, the magnetic force F _p becomes as follows: F _p = 2HS _p M (3) where M represents the magnetization of the rare earth magnet used.

Μ = 0.002 [NA-2], M = 0.8
Assuming [T], we compare the F and F _p.

Although S _p <S (4), when H is small, since M> μH, the latter type generates a larger force than the former type.

When H is large, the magnetization becomes saturated (maximum). This depends on the material, and the saturation magnetization in the case of silicon steel is H = 10 ⁵ [A /
m]. However, the linear region of the BH curve is M <
0.6 [T].

From these studies, when the distance between the former type object and the electromagnetic pole is small, F> F _p (5). However, as the spacing increases, the magnetic force decreases rapidly. Therefore, the latter type is very strong overall.

Another feature suitable for this actuator is that its force is proportional to the current I, whereas the pair of electromagnets has non-linear characteristics. That is, the magnetic force is a nonlinear function of the current I and the distance between the object and the pole.

FIG. 6 is a configuration diagram of a magnetic actuator of a magnetic levitation type micro hand showing an embodiment of the present invention. Here, 38 is a cylindrical coil, 38A is a coil end center, 3
9 is a permanent magnet.

The magnetic actuator is as follows.

(1) The number of turns n is 20,000 [/ m]. Here, when the coil length is 26 [mm], the number of turns is 5
00.

(2) Current I = 0 to 3 [A], (3) Area S = 3.14 × 10 ⁻⁴ [m ² ] Here, the inner and outer diameters of the coil are 20 and 32 [mm].

(4) S _p = 0.4 S Here, the diameter of the permanent magnet is 10 [mm] and the length is 40 [mm].

(5) M = 0.8 [T] Unlike FIG. 5, since the exciting coil is a single cylinder,
_p is determined from the force acting on a single magnetic pole.

F _p = HS _p M (6) According to equation (6), when I = 3 [A], the force is 600 [g].
f], whereas the actual force measured is I = 3
At the time of [A], it was 360 [gf]. The causes of this difference include the leakage of magnetic flux and the influence of the opposite pole.

FIG. 7 shows the force experimentally measured by changing the position of the permanent magnet inside the coil when I = 0.2 [A]. In FIG. 7, the vertical axis represents the force F (gf),
The horizontal axis is the magnetic pole position (mm). On the other hand, x and y indicate the magnetic pole position with the center of the coil end as the origin. This figure is
When the pole is near the center of the coil, it indicates that the force is almost constant.

[3] Characteristics of Control Here, characteristics of control of the actuator when the laser displacement sensor is used will be described. This laser displacement sensor (KEYENCE LK-2000) has the following functions.

(1) The resolution is 1 μm, (2) the measurement range is ± 5 mm, and (3) the response time is 512 μs. In the micro hand of the present invention, since the end effector is directly driven and the link mechanism has low friction, two control modes of position control and force control are possible. Here, a new system is evaluated using a PD-type controller that is effective for both control modes.

FIG. 8 is a schematic view of a one-axis experiment in place of the magnetic levitation type micro hand of the present invention.

Rare earth permanent magnet 43 and laser reflector 41
Is mounted on the driven body mounting part 42,
The coil 44 and the laser displacement sensor 45 are attached to a fixed part (not shown). The experiment was performed with two types of coils. These differ in the number of turns and diameter of the wire. In FIG. 8, reference numeral 46 denotes a balance weight. (1) Coil 1: When the number of turns is 500, diameter 0.5 When resistance is 4 [Ω], maximum force is 360 [gf] when I = 3 [A] (2) Coil 2: 2,000 turns, diameter 0.23 When the resistance is 100 [Ω], the maximum force is 110 [gf] when I = 0.2 [A]. The maximum value is limited by the capacity of the power supply (3 A, 36 V). Both coils are made by winding the same cylinder. Thus, the inductance of the coils L ₁ and L ₂ are the following relationship.

L ₂ = 16L ₁ (7) The coil 1 is the same as that used in the measurement of FIG.

FIG. 9 is a diagram showing the step response of both coils described above. The vertical axis represents the displacement (μm), and the horizontal axis represents time (s).

From this result, it can be seen that the response time and the overshoot are almost the same, but according to the data of the coil 2, in a stable state, larger vibration is shown. These results are described below.

(1) The coil 1 is stronger than the coil 2, but a small control gain must be used for the coil 1 due to the stability problem of the digital PD controller.

(2) Since the coil 2 has a large inductance, a voltage-to-current conversion circuit is used. However, since the influence of the inductance has not been completely removed, the vibration of the coil 2 is further increased.

Since the coil 1 exhibited better control characteristics, it was found that it was desirable to use the coil 1.

It should be noted that the present invention is not limited to the above embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0061]

As described above, according to the present invention, the following effects can be obtained.

(A) It is possible to provide an ultra-compact magnetic levitation type microhand capable of three-dimensional parallel operation.

(B) It is possible to directly drive the object and the end effector without contact. Furthermore, by introducing non-contact direct drive, low-friction drive is enabled, and highly accurate position control and force control can be performed. Further, the stroke width and linearity can be improved.

(C) By using a high-precision displacement sensor, high-precision control corresponding to the detection accuracy can be performed.

(D) The parallel link mechanism performs a parallelogram-like movement, so that a large reaction torque during machining is supported by the link mechanism, and the driving force of a relatively weak magnet is accurately applied to the end-end effector. Can be communicated to
And it can be miniaturized. Therefore, it is most suitable for a micromachine.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetic levitation type micro hand showing an embodiment of the present invention.

FIG. 2 is a schematic view of a parallel link mechanism of the magnetic levitation type micro hand according to the embodiment of the present invention.

FIG. 3 is a view showing a parallelogram parallel link mechanism having a shape close to a square of a magnetic levitation type micro hand showing an embodiment of the present invention.

FIG. 4 is a schematic view of a link mechanism of the magnetic levitation type micro hand showing the embodiment of the present invention.

FIG. 5 is a schematic view of various magnetic actuators.

FIG. 6 is a configuration diagram of a magnetic actuator of a magnetic levitation type micro hand showing an embodiment of the present invention.

FIG. 7 is a driving force characteristic diagram at the positions of various movers of the magnetic actuator of the magnetic levitation type micro hand according to the embodiment of the present invention.

FIG. 8 is a diagram showing a schematic view of a one-axis experiment in place of the magnetic levitation type micro hand showing the embodiment of the present invention.

FIG. 9 is a response characteristic diagram of an exciting coil in a one-axis experiment of a magnetic actuator of a magnetic levitation type micro hand showing an embodiment of the present invention.

[Explanation of symbols]

1,4,7 Magnetic actuator 2,5,8 Excitation coil 3,6,9 Rare earth permanent magnet 10 Driven body 11,12,13,45 Laser displacement sensor 14,16,17,18 Parallel link mechanism 15 Balance weight attachment Adapter 21 Fixing base 22 First parallel link mechanism mounting part 23, 25, 27, 28 Rotation axis 24 Top link 26 Bottom link 31 End effector 32 Working range 33 Sensor, actuator, end effector mounting part 34 Object 35 Iron core 36 , 44 Coil 37, 39 Permanent magnet 38 Cylindrical coil 38A Center of coil end 41 Laser reflector 42 Driven body mounting part 43 Rare earth permanent magnet 46 Balance weight

Claims (4)

[Claims] In a magnetic levitation type micro hand,
(A) a magnetic actuator comprising a mover made of a permanent magnet and a stator having an excitation coil fixed to a fixed portion and arranged to enable three-dimensional parallel driving; and (b) the magnetic actuator. A driven body driven by the driven body, (c) a displacement sensor for detecting displacement of the driven body, (d) a parallel link mechanism coupled to the driven body, and (e) the driven body or the driven body. An end effector attached to an end of the parallel link mechanism. 2. The magnetic levitation microhand according to claim 1, wherein the magnetic actuator has a stator composed of a cylindrical excitation coil and a movable element composed of a permanent magnet. 3. The magnetic levitation microhand according to claim 1, wherein the displacement sensor has a resolution of 1 μm order or more. 4. The magnetically levitated microhand according to claim 1, wherein the parallel link mechanism moves in a parallelogram manner and always keeps balance against gravity.