JP2585613B2 - Compliance device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a compliance device that elastically couples, for example, a robot hand and an arm, and more particularly to a variable compliance with respect to external vertical stress. Related to compliance devices.

(Conventional technology) Conventionally, as a tool for providing compliance to the robot wrist section as shown in Fig. 15, a device called an RCC (remote sensor compliance) device and a VACOM (variable compliance) device What is called is used. For example, as shown in “Precision Fitting Using Tactile Sense” (Journal of the Robotics Society of Japan, Vol. 2, No. 5, published in October 1984), the former RCC device is simply an elastic material such as a parallel leaf spring. The rigidity (reversal of compliance) cannot be changed. Therefore, for example, when performing a fitting operation on a robot, if the trajectory error at the time of fitting is large, and if the compliance is small,
The reaction force applied to the robot arm is large. Therefore, a VACOM-type device with variable compliance is required for application to precision work that requires assembly with a small force.

The latter VACOM device is a combination of a leaf spring structure and an electromagnet as shown in the above-mentioned publication or Japanese Patent Application Laid-Open No. 59-59389. Accordingly, the electromagnet displaces the leaf spring in a direction in which the stress applied to the leaf spring is relieved, thereby achieving compliance variability.

(Problems to be Solved by the Invention) However, the above-mentioned conventional compliance device,
Because both RCC type and VACOM type use leaf spring,
There is a risk of damage due to overload or aging fatigue.In particular, VACOM type devices have a structure that depends on the elasticity of the leaf spring, and although the rigidity can be varied to some extent, the operating load range etc. There are drawbacks such as being largely controlled by strength and the like.

In addition, as a compliance device that can solve the problem of aging such as a leaf spring, for example, Japanese Utility Model Laid-Open No. 53-4667
In No. 7, a plurality of permanent magnets are arranged on the oscillating disk, and a plurality of permanent magnets are also arranged on the fixed disk. There has been proposed an arrangement in which magnets are opposed to each other so as to repel each other.

The compliance device disclosed in Japanese Utility Model Application Laid-Open No. 53-46677 uses the above-described JP-A-59-59389.
Although the defect (deterioration due to aging) of the signal can be eliminated, the working load range is not variable that is uniquely defined by the strength of the permanent magnet used. Therefore,
To use it for a different purpose, the device itself needs to be changed. In addition, the opposing permanent magnets repel each other, so that they function as a compliance device with respect to an input that attempts to bring the swinging side closer to the fixed side. It has nothing to do with it.

Therefore, the present invention has been proposed in order to solve these drawbacks of the prior art, and is resistant to overload and aging, exhibits compliance with loads in any direction of front, rear, left, right, up and down, and has a working load range of It also provides a wide variable compliance device.

(Means and Actions for Solving the Problems) A compliance device according to the present invention for achieving the above object, which exhibits compliance to an externally applied load, is to form a space between the main body and the main body. A pair of first magnet members (1,5) fixed to the main body so as to face each other and forming a magnetic field parallel to a first direction; Arranged in the space between,
The main body is swingable around an axis in at least one of a second direction orthogonal to the first direction and a third direction orthogonal to both the second direction and the first direction. And a rod (4) extending in a direction parallel to the first direction for transmitting the load to the second magnet member. At least one of the set of the first magnet member and the second magnet member is an electromagnet so that the generated magnetic field intensity can be changed, and one of the set of the first magnet member and the second magnet member is the electromagnet. The first magnetic field formed between the second magnet member and the second magnet member is set in a direction in which the first magnetic member repels or attracts each other. The second magnetic field formed between them is also set in a direction to repel or attract each other. Wherein a pair of the first magnet member second magnet member,
The first magnet so that the second magnet member can take a stable state in the first direction, the second direction, and the third direction.
And the second magnetic field is magnetized so as to have a change in intensity in at least one of the second direction and the third direction.

(Operation) In the compliance device having the above configuration, the set of the first magnet member and the second magnet member transmit the first magnetic field and the second magnetic field respectively to the second direction and the third direction. Are magnetized so as to have a change in intensity in at least one of the directions, the second magnet member sandwiched between the pair of magnet members includes the first direction, the second direction, and the third direction. A stable state can be obtained in the direction (ie, the front-back direction, the left-right direction, the up-down direction). In other words, it exhibits compliance with an external load.
Here, “magnetized so as to have a change in intensity in at least one of the second direction and the third direction” means that the magnetization direction is parallel to the first direction, but the magnetization intensity distribution , For example, changes in a U-shape in the second direction.

Further, a first magnetic field formed between one magnet member of the set of first magnet members and the second magnet member is set in a direction to repel (or attract) each other. Since the second magnetic field formed between the other magnet member of the first magnet member of the set and the second magnet member is also set in a direction to repel (or attract) each other, the compliance device has The rod exerts compliance even when a load is applied to the rod, in particular, parallel to the first direction in either the forward direction or the reverse direction.

Also, since either the first magnet member or the second magnet member is configured as an electromagnet, the load range can be varied by controlling the current flowing through the electromagnet.

(Example) Hereinafter, a compliance device (hereinafter abbreviated as CD) of an example according to the present invention will be described with reference to the accompanying drawings.

<Principle of the magnet floating type CD> The feature of the CD of the present embodiment is as follows: The repulsive force (repulsive force) generated between the magnet and the movable part receiving the load is fixed to the fixed part fixed to the arm side of the robot. By utilizing and floating, the non-contact between the movable part and the fixed part is realized, and a conventional contact-type member such as a leaf spring is unnecessary. That is, it is a non-contact type RCC device by magnet suspension.

: A non-contact VACOM device with a magnet floating is realized by changing the magnet of the above device to an electromagnet.

: In the non-contact type compliance device based on the floating of the magnet, the direction of the compliance with respect to the displacement can be variously changed depending on the type of the distribution shape of the magnetic field intensity. For example, in the embodiment described below, -1: the compliance in the direction orthogonal to the axial direction of the robot arm and the compliance to the rotation around the axis in the orthogonal direction are changed (first embodiment). A description will be given of how to change the compliance of the robot arm in the axial direction and the compliance with rotation about the axis (second embodiment).

<First Embodiment> Principle FIG. 1 shows the principle configuration of the first embodiment. In this embodiment, a rectangular permanent magnet as shown in the figure is used to realize compliance in a direction orthogonal to the axial direction of the robot arm and compliance with rotation about the axis in the orthogonal direction. 2 are excreted between two electromagnets 1,5, also of rectangular shape. electromagnet
Reference numerals 1 and 5 are fixed to a pair of cases of the compliance device main body, and are therefore fixed to the robot arm. The permanent magnet 2 is axially supported by two support bars 3a and 3b orthogonal to the axial direction of the robot arm in the axial direction of the robot arm. However, as will be described in detail later, the support bars 3a and 3b are swingable in the axial direction of the bars. Reference numeral 4 denotes a rod for fixing the permanent magnet 2 to an external load (for example, a robot hand), and reference numeral 6 denotes a gap of the electromagnet 5 that allows the rod 4 to move freely within a certain range.

FIG. 2 is an X-direction arrow in FIG. Second
In the figure, reference numeral 8 denotes a fixing member for fixing the electromagnets 1 and 5 to each other (for example, the outer wall square tube 17 in FIG. 6). As can be seen from FIGS. 2 and 1, the extending directions of the support bars 3a and 3b are parallel to the sides of the rectangular magnet. However, the extension direction of the support bar is not essentially that it is parallel to the side direction of the magnet, but is that it has a predetermined direction for a specific distribution of the magnetic field intensity.

Therefore, returning to FIG. 1, the magnetic field distribution of each magnet will be described. In the figure, the hatching indicates the magnetic field strength. Then, a magnetic field of polarity N is generated on the lower surface of the electromagnet 1, and the change in the magnetic field strength is substantially inverted U-shaped when viewed from the arrow X direction, and the change in the strength is so small in the axial direction of the support bar. ing. On the other hand, the locality of the magnetic field on the upper surface of the electromagnet 5 is S, and the change in intensity is opposite to that of the electromagnet 1 as shown in FIG. The polarity of the magnetic field on the upper surface of the permanent magnet 2 is N
Therefore, the electromagnet 1 generates a repulsive field therebetween. The lower surface of the permanent magnet 2 is S-polar and generates a repulsive field with the magnetic field on the upper surface of the electromagnet 5. The change in the magnetic field strength of the permanent magnet 2 depends on the direction of the support bar (hereinafter, referred to as A direction).
And there is not much change, and it is substantially U-shaped in a direction perpendicular to the support bar.

According to the magnetic field strength distribution as described above, the permanent magnet 2 is almost at the center of the electromagnets 1 and 5 due to the repulsive magnetic force (repulsive force).
Stabilizes in an almost horizontal state. FIG. 3 shows the characteristics of the repulsive force generated when the robot arm is displaced in the axial direction of the support bar. Similarly, FIG. 4 shows the characteristics when the robot rotates about the axis of the support bar (hereinafter referred to as the B direction). 9 shows a repulsive couple characteristic with respect to a rotation angle. As is apparent from FIG. 3, when the permanent magnet 2 is displaced in the direction A, a repulsive force acts in the direction opposite to the displacement substantially in proportion to the amount of displacement, and therefore, is most stable when the displacement is zero. . However, the positive and negative signs in FIG. 3 indicate that the rightward displacement and the rightward force (repulsive force) when viewed from the X direction in FIG. 1 are positive. Similarly, from FIG.
The most stable state is obtained when the rotation angle in the direction is zero, and the greater the rotation angle, the greater the force (couple) that is going to return to the original state. In FIG. 4, the angle and couple are negative in the clockwise direction and positive in the counterclockwise direction.

In the embodiment shown in FIG. 1, the electromagnets 1 and 5 supply the N-polarity and S-polarity magnetic fields to the permanent magnet 2 respectively. It is obvious that there is none.

Detailed Configuration FIGS. 1 to 4 show the conceptual configuration of the first embodiment. Therefore, FIGS. 5A, 5B and 6 show more detailed and specific configurations of the present compliance device. 5A and 5B are plan views of the electromagnets 1 and 5, respectively. FIG. 6 is a plan view of the electromagnet 1 taken along the line YY (FIG. 5A) and the electromagnet 5 taken along the line ZZ (FIG. 5B). FIG. 4 is a cross-sectional view when the compliance device is cut.

Referring to FIG. 6, the coils 15a and 15b and the coil core 1
The electromagnet 1 is constituted by the 4a, 14b and the iron core plate 14a. Similarly, coils 15a, 15b, coil iron cores 14a, 14b, iron core plate 10b
Is used to form the electromagnet 5. Since the electromagnets 1 and 5 of FIG. 1 supply magnetic fields of N and S polarities, respectively,
Can be covered by one coil (15a or 15b)
This compliance device uses a plurality of coils as shown in FIG. 5 because the distribution of the electric field strength shown in FIG. 1 is changed.

That is, in FIG. 6, when a current is applied to the coil 15a and the coil 15b, a clockwise magnetic path of the iron core 14a, the iron core plate 10a, the air layer permanent magnet 12, the iron core plate 10b, the coil 14a,
Iron core 14b Iron core plate 10b Air layer permanent magnet 12 Iron core plate 10b
The counterclockwise magnetic path of the coil 14b is connected to the iron core plates 10a and 10a.
A magnetic field of NS is formed between the magnetic field and 0b.

The support bars 13a, 13b are pivotally supported by holes provided in the outer wall square tubes 19a, 19b of the compliance device main body. Bar 1
3a and 13b serve as air bearing supports to reduce friction. That is, the air sent from the air pipes 16a and 16b is sent to the pneumatic chambers 17a to 17d, and further passes through the air passages 18a to 18d and into the holes that support the bars 13a and 13b.

5A and 5B show the arrangement of the electromagnet coils 1 and 5 for obtaining the magnetic field distribution shown in FIG. The plurality of coils are divided into four groups A to D,
The magnetic field distribution shown in the figure is obtained. The magnetic insulator separating the iron core plates is made of a material having a low magnetic permeability (for example, a copper alloy or a glassy ceramic).

Variable Compliance Device To make the compliance characteristic variable, A to D
It is obtained by adjusting the amount of current flowing through the coils divided into groups. For example, by applying a larger current to the coils of the groups A and B and applying a smaller current to the coils of the groups B and D, the electromagnetic distribution shown in the figure can be obtained. Further, when the rigidity in the A direction is weakened, the current amounts of the groups A and B are reduced, and when the rigidity in the A direction is increased, the current amounts of the groups A and B are increased. When the rigidity in the B direction is reduced, the current amounts of the groups C and D are reduced,
Conversely, when increasing the rigidity in the B direction, the current amounts of the C and D groups are increased.

7A to 7D show guidelines for changing the magnetic field strength when the compliance characteristic is weakened or strengthened. These characteristic changes will be easily understood in connection with FIG. 3 and FIG. FIG. 8 shows a current (unit: amperes) flowing through the coils of the groups A to D for obtaining the magnetic field characteristics shown in FIGS. 7A to 7D. The coils in the same group are connected in parallel with each other.

With the above method, the rigidity in the direction A and the rigidity in the direction B can be varied almost independently.

The electromagnets 1 and 5 are not both required. For example, even without the electromagnet 1, the compliance characteristic in the A direction can be obtained.

<Second Embodiment> The second embodiment has a compliance (longitudinal rigidity) in the axial direction of the robot arm and a compliance (torsional rigidity) in rotation around the axis (RC).
C type) and further change them (VACOM type).

In FIG. 9, the electromagnets 21 and 25 have their supporting cylinders (first
It is fixed to the compliance device main body by 31a and 31b in FIG. The permanent magnet 22 fixed to the rod 24
Depending on the load, it can slide in the axis (vertical) direction of rod 24,
And it is rotatable around its axis. The longitudinal rigidity is realized by the repulsive force of the N-polar magnetic field by the lower surface of the electromagnet 21 and the S-polar magnetic field by the upper surface of the permanent magnet 22, and the repulsive force of the S magnetic field by the lower surface of the permanent magnet 22 and the S magnetic field by the upper surface of the electromagnet 25. This is the same as in the first embodiment.

The torsional rigidity is realized by having a magnetic field distribution as shown by hatching in FIG. That is, as an example, an electromagnet
Considering the force acting between the permanent magnet 21 and the permanent magnet 22, the N-polar magnetic field generated by the electromagnet 21 has two peaks and two valleys as strengths. On the other hand, the N-polar magnetic field of the permanent magnet 22
It has two valleys and two peaks in phase opposition to 21. According to the magnetic field having such a magnetic field distribution, the permanent magnet 22 obtains a stable state at two circumferential points. This focuses on the imaginary micromagnet of the permanent magnet 22, integrates the electromagnetic force of all the micromagnets on the electromagnet 21 with respect to this micromagnet, and further integrates the micromagnet on the micromagnet on the permanent magnet 2. It is obtained by integrating the electromagnetic force on the permanent magnet 22. According to this concept, as shown in FIGS. 10A and 10B, if the magnetic field distribution is axisymmetric, the point where the peaks and valleys of the magnetic field of the electromagnet 21 and the permanent magnet 22 coincide (they are on the line of symmetry). Thus, a stable state is obtained in the torsional direction.

It is desirable that the change in the magnetic field strength can ensure periodicity and symmetry as shown in FIG. If such a magnetic field characteristic is not obtained, "smoothness", linearity, and symmetry in the torsional direction cannot be obtained in the compliance characteristic. Also, if the number of mountains is one,
There is only one stable point, and it can follow a 360 degree twist change. As the number of peaks and valleys is increased, the compliance (rigidity) with respect to minute torsion relatively increases.

As shown by the dashed line in FIG.10B, when the permanent magnet is twisted, the energy of the space between the electromagnet and the permanent magnet increases, and a couple is generated in a direction to reduce the energy, that is, a direction opposite to the twist. . This couple becomes compliance with torsion.

Further, in the embodiment shown in FIG.
Although one is provided, any one of the electromagnets 21 and 25 may be used as long as it is a compliance device for torsional rigidity.

In the embodiment shown in FIG. 9, the electromagnets 21 and 25 are
Are supplied with N-polarity and S-polarity magnetic fields, respectively. However, even if the magnetic fields are supplied in the order of NS, this is no problem as in the first embodiment.

Detailed Configuration FIG. 11 shows a detailed cross-sectional view of the compliance device according to the second embodiment. The second embodiment differs from the first embodiment in that the rod 24 slides in the vertical direction. Therefore, in order to make the air bearing structure in the sliding part, small holes
33 and 34 are provided. Also, the supporting cylinders (31a, 31b), which are also made of a material having low magnetic permeability, prevent the permanent magnets from being affected by the magnetic field from the outer coil inside the device.
And the above-mentioned iron core plates (30a, 30b).

FIG. 12 shows a coil configuration, an iron core plate shape, and the like for obtaining a magnetic field strength as shown in FIG. As in the case of the first embodiment, the coils in the same group are connected in parallel, and current control can be performed independently between the groups.

Variable Compliance Device In order to make this compliance device variable, the current flowing through each coil may be changed as in the first embodiment. FIGS. 13A to 13D show changes in magnetic field characteristics when the longitudinal rigidity is reduced, increased, the torsional rigidity is decreased, and the torsional rigidity is decreased, respectively. FIG. 14 shows the value of the current flowing through the coils of the groups A to D, corresponding to FIGS. 13A to 13D.

<Effects of the Embodiments> The two embodiments have been described above. However, in these embodiments, since a support structure using a spring or the like is not used, damage due to overload or damage due to fatigue does not occur. In addition, by changing the magnetic field strength of the electromagnet, the compliance can be varied, and at the same time, the rigidity can be changed in a wide range according to the application, so that the working load range is greatly expanded. Effects can be obtained.

(Effect of the Invention) As described above, according to the compliance device of the present invention, it is possible to exhibit compliance with any load in the front-rear, left-right, up-down directions, and to make the working load range variable. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle configuration of a compliance device according to a first embodiment of the present invention, FIG. 2 is a side view of the first embodiment as viewed from the X direction, FIG. 3 and FIG. 5A and 5B are plan views of electromagnets 21 and 25, respectively, FIG. 6 is a cross-sectional view of the first embodiment, FIGS. 7D is a diagram showing a magnetic field intensity change when the rigidity is changed in the first embodiment, FIG. 8 is a diagram showing a current value flowing through the coil when the magnetic field intensity is changed, and FIG. FIG. 10A and FIG. 10B are diagrams illustrating the principle of torsional compliance generation, FIG. 11 is a cross-sectional view of the second embodiment, FIG. FIG. 12 is a plan view of the electromagnet 21 of the second embodiment, and FIGS. 13A to 13D show rigidity in the second embodiment, respectively. FIG. 14 is a diagram showing a change in magnetic field strength when the magnetic field strength is changed, FIG. 14 is a diagram showing a current value flowing through a coil when the magnetic field strength is changed in the second embodiment, and FIG. 15 is a conventional example and this embodiment. FIG. 5 is a diagram illustrating a use position of a compliance device in a robot system using the compliance device according to the first embodiment. In the figure, 1,5,21,25 …… electromagnet, 2,12,22 …… permanent magnet, 3a, 3b, 13
a, 13b …… Support bar, 4,24 …… Rod, 6,11 …… Void, 1
0a, 10b, 30a, 30b ... iron core plate, 14a, 14b ... coil iron core, 1
5a, 15b …… Coil, 16a, 16b …… Air supply pipe, 17a-17d
... pneumatic chambers, 18a, 18b ... small holes, 19a, 19b ... outer wall square cylinders.

Claims (5)

(57) [Claims] 1. A compliance device for exhibiting compliance against an externally applied load, wherein said compliance device is fixed to said body so as to oppose each other so as to form a space between said body and said first device. And a pair of first magnet members (1,5) forming a magnetic field parallel to the direction, and disposed in the space between the pair of first magnet members, and orthogonal to the first direction. A second magnet swingably supported by the body about an axis in at least one of a second direction and a third direction orthogonal to both the second direction and the first direction; A member (2); and a rod (4) extending in a direction parallel to the first direction for transmitting the applied load to the second magnet member, wherein the set of first magnet members is And at least one of the second magnet members changes the intensity of the generated magnetic field. Possible is an electromagnet so, said the one of the magnet member of the pair of the first magnet member second
The first magnetic field formed between the first magnet member and the second magnet member is set so as to repel or attract each other. The second magnetic field formed by is also set in a direction to repel or attract each other, and the pair of the first magnet member and the second magnet member are such that the second magnet member is in the first direction. , Second direction, third
The first magnetic field and the second magnetic field are magnetized so as to have a change in intensity in at least one of the second direction and the third direction so that a stable state can be obtained in the direction of. A compliance device, characterized in that: 2. The second magnet member is a permanent magnet body fixed to the main body so as to be rotatable around an axis parallel to the second direction, wherein the set of second magnet members is The compliance device according to claim 1, wherein the compliance device is an electromagnet. 3. The compliance device according to claim 1, wherein the rod penetrates one of the pair of second electromagnet members. 4. The second magnet member is supported by the main body by a support bar (3) rotatable about an axis parallel to the second direction, and has a substantially rectangular cross section in the magnetic field direction. The cross-sectional shape in the direction of each magnetic field is substantially rectangular,
The distribution of the magnetic field strength of each of the pair of first magnet members is substantially U-shaped in a direction perpendicular to both the rod and the support bar.
The distribution shape of the magnetic field intensity of the second magnet member is substantially U-shaped in the direction of the support bar, and the compliance of the device is in the axial direction of the support bar and the bar. 4. The compliance device according to claim 3, wherein the direction of rotation is around. 5. The second magnet member has a substantially circular cross section in a magnetic field direction, and each of the second magnetic members has a substantially circular cross section in a magnetic field direction. The distribution shape of the magnetic field strength of the magnet member has peaks and valleys at least on the circumference of the circle, and the peaks and valleys on the circumference of the distribution shape of the magnetic field strength of one surface of the second magnet member are: 9. The device according to claim 8, wherein the magnetic field intensity distribution of the one magnet member coincides with the valleys and peaks of the magnetic field intensity, and the compliance of the device is an axial direction of the rod and a rotational direction around the axis of the rod. 4. The compliance device according to range 3,