JP2000120824A - Parallel link mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce burden applied on an actuator, and improve controllability by providing a load burdening means for burdening a part of a load applied on a movable part by magnetic force, as a parallel link mechanism for driving the movable part with a plurality of freedoms, on a base part fixed to a prescribed position of a space. SOLUTION: Support is carried out between a flexible part 1 and a base part which are arranged opposing to each other at clearances, and permanent magnets 7, 9 are arranged on each opposing surface of the flexible part 1 and the base part 5 so as to mutually repel opposing both poles to each other. In this case, a magnetic field generated by the permanent magnet 9 is radiated in a cone shape from a cylindrical magnetic field of an upper end part of the permanent magnet 9. A circumferential length of the permanent magnet is formed shorter than that of the permanent magnet 9 so as to magnetic levitate the permanent magnet 7. In the case where a load is applied on an upper surface of the movable part 1, a part of the load is supported by bounce of the permanent magnets 7, 9 so as to reduce burden of the load applied on a close coupled actuator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel link mechanism, and more particularly to a parallel link mechanism having improved controllability by reducing a load on an actuator of the parallel link mechanism.

[0002]

2. Description of the Related Art In recent years, parallel link mechanisms have attracted attention in terms of high rigidity, high speed, high accuracy, and the like, and cases of use in machine tools, assembling robots, and the like are increasing. FIG. 5 shows a specific example of the parallel link mechanism.

[0003] The parallel link mechanism 10 has a movable section 1 of six.
This is a type driven by a linear motion type actuator 3 and is generally called a Stewart platform. A movable portion (traveling plate) 1 is fixed to an upper end portion of the direct-acting actuator 3 via a pair (not shown). On the other hand, the lower end of the direct acting actuator 3 is connected to a base (base plate) 5 via a pair (not shown).
It is fixed to.

A pneumatic / hydraulic actuator, a motor, a ball screw, a jack, a piezoelectric element, and the like are used for driving the parallel mechanism. In particular, piezoelectric elements
Since the accuracy and resolution are extremely high, application to various fields is expected.

[0005]

By the way, in the conventional parallel link mechanism 10, usually, the movable part 1 is provided with a base part 5 so that the operation by the linear actuator 3 can be easily performed.
Is located at a certain distance from

[0006] Normally, a device or the like is attached to the movable part 1, and in order to secure a constant distance as described above, the movable part 1 applies a constant force (hereinafter referred to as a constant) to the direct-acting actuator 3. , Biasing force) is required. When using an actuator with strong nonlinear characteristics such as a piezoelectric element,
This bias force limits the linear range of motion.

Further, when the inclination of the linear actuator 3 increases, the bending force of the linear actuator 3 increases, and the linear actuator 3 is easily broken. Further, if the inclination is large, the horizontal component of the force acting on the movable portion 1 by the direct-acting actuator 3 becomes larger than the vertical component, and it becomes difficult to extend the direct-acting actuator 3.

Further, when a jack or the like is used as the direct-acting actuator 3, if the load applied to the movable portion 1 suddenly increases or decreases, the contact or breakage of the device due to sudden expansion and contraction of the direct-acting actuator 3 occurs. Was likely to occur.

The present invention has been made in view of such conventional problems, and has as its object to provide a parallel link mechanism having improved controllability by reducing the load on the actuator of the parallel link mechanism. .

[0010]

SUMMARY OF THE INVENTION Therefore, the present invention provides a parallel link mechanism for driving a movable portion with any one of two to six degrees of freedom with respect to a base fixed at a predetermined position in a space. The apparatus is provided with a load-bearing means that bears a part of the load applied to the movable portion by magnetic force.

A load is applied to the movable part. Due to this load, a part of the load is applied to, for example, a direct-acting actuator constituting each degree of freedom. When the control characteristic of the direct-acting actuator includes a non-linear region, the control point may enter the non-linear region due to the movement of the control point due to a change in load.

For this reason, in order to reduce the amount of movement of the control point due to the fluctuation of the load, a part of the load applied to the movable part is borne by the load borne means. The load bearing means bears part of the load in a non-contact manner by the magnetic force. The load burden at this time is
This is mainly equivalent to the bias force. Since the actuator only needs to bear the remaining load that has been borne by the load weighing means, the control points can be accommodated in the linear region.

Thus, the controllability of the parallel link mechanism can be improved. Further, since the load-bearing means bears the load in a non-contact manner, the load-bearing means does not exert an effect such as twist on the movable portion or the like.

Further, according to the present invention, the load-bearing means includes a permanent magnet or an electromagnet disposed on the base portion, and a permanent magnet or an electromagnet disposed on the movable portion with the magnetic pole surface facing the permanent magnet or the electromagnet. And characterized by the following.

By the magnetic force of the permanent magnet or the electromagnet,
Part of the load applied to the actuator is borne. The permanent magnet or the electromagnet is disposed on the base and the movable part with the magnetic pole faces facing each other. The magnetic pole faces to be confronted are determined to be the same magnetic pole or to the opposite magnetic pole depending on the purpose of use and method of use of the parallel link mechanism. That is, the polarities of the magnetic poles facing each other in the direction of reducing the load on the movable portion are determined.

The permanent magnet or the electromagnet may be fixed on the front or back surface of the base and the movable portion, or may be embedded. Further, the permanent magnet or the electromagnet may be disposed so that one pair is located at the center of each of the base and the movable part, or a plurality of permanent magnets or the electromagnet may be disposed evenly between the base and the movable part. Good. As a result, the controllability of the parallel link mechanism can be improved at low cost. In the case of permanent magnets, maintenance is easy.

When an electromagnet is used, the electromagnetic force may be constant at all times, but the electromagnetic force may be adjusted according to the load applied to the movable part. At this time, the amount of burden on the load bearing means can be adjusted. Therefore, an optimal linear region of the actuator can always be ensured irrespective of the variation of the load amount. If the electromagnet is provided only on the base side, the wiring can be neatly arranged.

In this case, the cost is low because one of them is a permanent magnet. However, if a device such as wiring is passed through the inside of the actuator and the inside of the movable portion, the wiring can be neatly arranged even when the electromagnet is arranged on the movable portion side.
Further, even if the permanent magnet or the electromagnet is aged, it can be easily dealt with by finely adjusting the amount of current supplied to the electromagnet. Further, it is not necessary to always supply an exciting current to the electromagnet, and it may be allowed to flow only when a load is applied for power saving.

Further, according to the present invention, the peripheral length of the magnetic pole facing the base of the permanent magnet or the electromagnet disposed on the movable portion may be the same as that of the permanent magnet or the electromagnet disposed on the base. It is characterized in that it is smaller than the circumference of the magnetic pole facing the movable part.

The circumference of the magnetic pole of the permanent magnet or electromagnet disposed on the movable portion side is made smaller than the circumference of the magnetic pole of the permanent magnet or electromagnet disposed on the base portion side. Therefore, the permanent magnets and the like disposed on the movable portion side are surrounded by the lines of magnetic force radiated from the permanent magnets and the like disposed on the base side.
By changing the circumference in this way, the stability of the permanent magnet and the like disposed on the movable section side is improved.

Further, according to the present invention, the entirety of the permanent magnet and / or the electromagnet provided at the base and / or the movable portion or at least the facing magnetic pole portion is formed in a cylindrical shape.

The whole of the permanent magnet and / or the electromagnet is formed in a cylindrical shape. Further, at least the opposed magnetic pole portions may be formed in a cylindrical shape. By making the magnetic pole portion cylindrical, the lines of magnetic force radiated from the cylinder surround a facing permanent magnet or the like in a mortar shape in the direction of the extension of the center of the cylinder. Therefore, the permanent magnet and the like are stabilized in the direction of the extension of the center of the cylinder.

Further, according to the present invention, the movable portion is made of a magnetic material, and the load-bearing means is fixed at a predetermined height above the movable portion above the movable portion to attract or repel the movable portion. And at least one electromagnet.

The movable part is made of a magnetic material. At least one electromagnet fixed above the movable portion at a predetermined height from the base is provided. In other words, the load applied to the movable part is borne by attracting the movable part upward or repelling it downward by the electromagnet. At this time, suction or repulsion can be selected by changing the type of the magnetic material. The selection of suction or repulsion is determined according to the purpose and method of use of the parallel link mechanism.

Further, according to the present invention, the electromagnets are evenly opposed to the edges of the movable portion so as to attract or repel the movable portion in a well-balanced manner. By uniformly sucking or repelling the edge of the movable portion, the movable portion can be held in a well-balanced manner.

Further, according to the present invention, the load-bearing means further includes at least one electromagnet disposed on the base to attract or repel the movable portion. An electromagnet is also provided on the base side to attract or repel the movable part.

Therefore, the load of the load applied to the movable portion can be adjusted according to the load amount, with a better balance. In addition, since the loads are almost equally applied to the actuators, a linear region can be secured irrespective of the variation in the load amount. Therefore, the controllability of the parallel link mechanism can be improved.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a first embodiment of the present invention. In FIG. 1, the configuration of the parallel link mechanism 10 is the same as the conventional one. The six linear actuators 3 are composed of, for example, piezoelectric elements. However, the present invention is applicable as long as the number of the linear actuators 3 is two or more.

Further, a direct-acting actuator and a method of disposing a pair (even pair is omitted in FIG. 1) for connecting the direct-acting actuator to a movable portion or a base portion are as follows.
The present invention is not limited to FIG. 1, but may be any one of two to six degrees of freedom.

At the center of the bottom surface of the movable portion 1 of the parallel link mechanism 10, a hollow cylindrical permanent magnet 7 is fixed.
On the other hand, a hollow cylindrical permanent magnet 9 is provided at the center of the upper surface of the base 5.
Are fixed so that the same poles are opposed to the permanent magnets 7. The circumference of the permanent magnet 7 is configured to be shorter than the circumference of the permanent magnet 9.

Next, the operation of the first embodiment of the present invention will be described. In FIG. 1, the permanent magnet 7 and the permanent magnet 9 repel each other because the same poles face each other. The magnetic field generated by the permanent magnet 9 is radiated from the cylindrical magnetic pole at the upper end of the permanent magnet 9 in a mortar shape. Since the perimeter of the permanent magnet 7 is shorter than the perimeter of the permanent magnet 9, the permanent magnet 7 magnetically levitates so as to be surrounded by this magnetic field. That is, the permanent magnet 7
Is stable, and the direction of repulsion does not change due to the inclination of the movable portion 1.

Consider a case where a load is placed on the upper surface of the movable unit 1 or the like. At this time, since the piezoelectric element constituting the direct acting actuator 3 has a non-linear characteristic, the control point may enter a non-linear region. On the other hand, a part of the load is supported by the repulsive force of the permanent magnet 7 and the permanent magnet 9. Then, the load on the direct acting actuator 3 (corresponding to the bias force) is reduced. As a result, the control points can be put in the linear region, and the control performance can be improved.

When the distance between the movable portion 1 and the base 5 is reduced, the permanent magnet 7 and the permanent magnet 9 are moved by a larger force.
To support. Accordingly, when the inclination of the linear motion actuator 3 is large, the break of the link is prevented, and the expansion and contraction of the linear motion actuator 3 can be performed with less force.

The permanent magnet 7 and the permanent magnet 9 have been described as repelling. However, when the movable part 1 is below the base 5 and a load is applied downward, or when the parallel link mechanism 10 rotates 90 degrees. When the load is applied so that the distance between the movable portion 1 and the base portion 5 is increased, the permanent magnets 7 and 9 are configured to attract the magnetic poles.

A plurality of pairs of the permanent magnets 7 and the permanent magnets 9 may be equally arranged between the movable part 1 and the base part 5.

Further, the permanent magnet 7 is fixed to the center of the bottom surface of the movable portion 1 and the permanent magnet 9 is fixed to the center of the upper surface of the base portion 5. However, both the permanent magnet 7 and the permanent magnet 9 are fixed to the movable portion 1 and the base portion. 5 can also be embedded.

It is also possible that the whole of the movable part 1 and / or the base part 5 is a disk-shaped permanent magnet.

Next, FIG. 2 shows a configuration diagram of a second embodiment of the present invention. The same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 2, a permanent magnet 17 is fixed to the center of the bottom surface of the movable portion 1. On the other hand, at the center of the upper surface of the base 5, an electromagnet 19 is
7 are fixed to face each other. The circumference of the permanent magnet 17 is shorter than the circumference of the electromagnet 19.

Next, the operation of the second embodiment of the present invention will be described. In FIG. 2, the permanent magnet 17 is attracted or repelled by the electromagnet 19. This attraction or repulsion is adjusted so that a magnetic force acts in a direction against a load applied to the movable portion 1. The peripheral length of the permanent magnet 17 is
, The floating of the permanent magnet 17 is easily stabilized.

If the upper magnetic pole portion of the electromagnet 19 is formed in a cylindrical shape, or the entire core of the electromagnet 19 is formed of a hollow cylinder, the permanent magnet 17 is surrounded by a magnetic field. Stabilization. Also, temporarily,
Even if the permanent magnet 17 or the electromagnet 19 changes over time, it can be easily dealt with by finely adjusting the amount of current supplied to the electromagnet 19.

It should be noted that no current flows through the electromagnet 19 in a stationary state in which no load is applied to the movable part 1. Further, the current flowing through the electromagnet 19 may be changed in accordance with the size of the load to perform control such as always securing an optimal linear region of the direct acting actuator 3.

It should be noted that an electromagnet can be provided instead of the permanent magnet 17. In this case, by embedding the electric wires in the movable portion 1 and the linear motion actuator 3, it is possible to prevent the electric wires from being output to the outside. Further, a plurality of pairs of the permanent magnet 17 and the electromagnet 19 may be equally arranged between the movable part 1 and the base part 5.

Next, FIG. 3 shows a configuration diagram of a third embodiment of the present invention. 1 and 2 are denoted by the same reference numerals and description thereof is omitted. In FIG. 3, the movable unit 1 is made of a magnetic material (for example, a paramagnetic material). Above the edge of the movable part 1, electromagnets 29A, 29B, 29C,
29D are arranged in a balanced manner in four directions as shown in FIG. Electromagnets 29A, 29B, 29C, 29D
Are pillars 21A, 21B having windings suspended from the base 5,
It is wound around 21C and 21D.

Next, the operation of the third embodiment of the present invention will be described. In FIG. 3, in a stationary state in which no load is applied to the movable unit 1, none of the electromagnets 29A, 29B, 29C, 29D and the electromagnet 19 are excited. Therefore, no power is consumed.

When a load is applied to the movable part 1 in the downward direction, the movable part 1 is a paramagnetic substance, and therefore the electromagnets 29A,
29B, 29C, and 29D carry a part of the load by sucking while maintaining the balance of the movable unit 1. On the other hand, the electromagnet 19
, An exciting current is passed so that the upper magnetic pole of the electromagnet 19 is the same as the magnetic pole induced on the bottom surface of the movable unit 1. Therefore, a part of the load is applied to the movable part 1 by the repulsive force of the electromagnet 19.

When a load is applied to the movable unit 1 in the upward direction, the electromagnet 19 attracts the movable unit 1. An exciting current is applied to the lower magnetic poles of the electromagnets 29A, 29B, 29C, and 29D so as to have the same polarity as the magnetic poles induced on the upper surface of the movable unit 1.

Accordingly, the movable part 1 is provided with the electromagnets 29A and 29A.
Part of the load is borne while being balanced by the repulsive forces of B, 29C and 29D. The electromagnet 29A,
Exciting currents of different magnitudes can flow through 29B, 29C and 29D in order to balance the movable part 1.

The electromagnets 29A, 29B, 29C, 2
The number of 9Ds is not limited as long as they are arranged evenly above the edge of the movable section 1. Further, a plurality of electromagnets 19
May be arranged evenly.

Next, when the magnetic material of the movable portion 1 is a diamagnetic material, the attraction and repulsion of the movable portion 1 by the respective electromagnets are reversed. Therefore, the direction of the load burden is also reversed.
The selection of suction or repulsion and the selection of the magnetic material may be performed according to the purpose and method of use of the parallel link mechanism.

The electromagnets 29A, 29B, 29C, 2
9D, the excitation of the electromagnet 19 may be automatically started or stopped by a weight sensor for detecting the load amount, a position sensor for detecting the position of the movable unit 1, or the like, or the load amount may be estimated in advance. In this case, a predetermined exciting current may be supplied manually.

A part of the electromagnet can be a permanent magnet. Also, the electromagnets 29A, 29B, 29
C and 29D are used to connect the windings to the columns 21A, 21B, 21C, 2
Although it is configured to be wound around 1D, a winding having a winding wound around an independent iron core may be used.

As described above, a part of the load can be borne while maintaining the balance of the movable portion 1. Therefore, the load applied to each of the linear motion actuators 3 is also substantially constant, and the control points can be easily stably put in the linear region.

[0053]

As described above, according to the present invention, since the load-bearing means is provided, the bias force applied to the actuator by the load can be offset or reduced. Therefore, the controllability of the parallel link mechanism can be improved.

Further, since the load-bearing means is constituted by permanent magnets and / or electromagnets, the load-bearing means and the inclined movable part can be supported in a non-contact manner. In addition, maintenance can be performed easily at low cost.

Further, since the opposed magnetic pole portions are machined into a cylindrical shape and the circumference is changed, the position of the movable portion can be easily stabilized.

[0056]

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 shows an example of disposing an electromagnet above a movable part according to a third embodiment of the present invention.

FIG. 5 is a configuration example of a conventional parallel link mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Movable part 3 Direct-acting actuator 5 Base 7, 9, 17, 19 Permanent magnet 21A, 21B, 21C, 21D Column 29A, 29B, 29C, 29D Electromagnet

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02N 15/00 H02N 15/00 (72) Inventor Akira Shimada 4-3-1 Yashiki, Narashino-shi, Chiba Pref. F term (reference) in Koseiki Co., Ltd. 5H303 AA01 AA10 BB03 BB09 CC08 DD01 DD04 DD08 DD11 DD14 QQ01 QQ09 5H680 BB13 BC08 BC09 DD23 DD76

Claims (7)

[Claims] 1. A base fixed to a predetermined position in a space,
A parallel link mechanism for driving a movable portion with any one of 6 to 6 degrees of freedom, comprising: a load-bearing means for bearing a part of a load applied to the movable portion by a magnetic force. mechanism. 2. The load-bearing means comprises a permanent magnet or an electromagnet disposed on the base, and a permanent magnet or an electromagnet disposed on the movable portion with the magnetic pole surface facing the permanent magnet or the electromagnet. The parallel link mechanism according to claim 1, wherein: 3. A circumferential length of a magnetic pole facing the base of the permanent magnet or the electromagnet provided on the movable portion, the circumference of the magnetic pole facing the movable portion of the permanent magnet or the electromagnet provided on the base. 3. The parallel link mechanism according to claim 2, wherein the peripheral length of the magnetic pole is smaller than that of the magnetic pole. 4. The whole or at least opposing magnetic pole portion of the permanent magnet and / or the electromagnet disposed on the base and / or the movable portion is formed in a cylindrical shape. The parallel link mechanism according to claim 3. 5. The movable portion is made of a magnetic material, and the load-bearing means is at least one fixed at a predetermined height above the movable portion above the movable portion to attract or repel the movable portion. 2. The parallel link mechanism according to claim 1, wherein the parallel link mechanism includes an electromagnet. 6. The parallel link mechanism according to claim 5, wherein the electromagnets are evenly arranged to face the edge of the movable portion so as to attract or repel the movable portion in a balanced manner. . 7. The parallel link mechanism according to claim 5, wherein said load-bearing means further comprises at least one electromagnet disposed on said base for attracting or repelling said movable part.