JPS61226285A - Supporter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Table of Contents] Industrial Application Fields Prior Art Problems to be Solved by the Invention Means for Solving the Problems Effects of the Invention [Industrial Application Fields] The present invention This invention relates to an improvement in the structure of a support device having a third member that supports a plate-like elastic body and a displacement regulating means that regulates displacement of the plate-like elastic body.

In recent years, industrial robots have been frequently introduced into production lines. However, since position-controlled robots operate regardless of restraining forces from the environment, it is extremely difficult to introduce them into assembly line automation, which requires delicate control of force.

This is because there are many assembly operations that require absolute positional accuracy, such as fitting and mounting of components.

If fitting parts is to be performed by a position-controlled robot, it is necessary to accurately describe the movement locus determined from the assembly object with respect to robot coordinates, and to precisely control the tip to follow a predetermined locus.

However, in actual position control type robots, it is extremely difficult to increase the absolute position accuracy due to mechanical errors and control errors of the robot itself.

For this reason, in assembly robots, a compliance mechanism for correcting or absorbing relative positional errors between the robot and the object is provided at the wrist between the robot and the hand.

Further, the amount of error correction or absorption that can be corrected or absorbed by the compliance mechanism provided at the wrist is extremely small, and therefore it is not possible to correct or absorb the relative position error between the robot and the object.

For this reason, the above-mentioned relative position error is detected as a reaction force generated at the wrist, and the reaction force is detected in order to feed back the detected reaction force to the robot and correct the position of the robot so that the reaction force becomes zero.・Development of force detection devices (sensors) is progressing.

FIG. 11 is a diagram for explaining such a compliance mechanism and force detection device.

In the figure, 9 is a parallel spring in the X direction, 10 is a parallel spring in the Y direction, and the force detection device 6 is constituted by two sets of parallel plate springs 9 and 10 that can be displaced in the X direction and the Y direction, which are orthogonal to each other. ing.

Therefore, the upper part of the force detection device 6 can be displaced in the X direction by the parallel leaf spring 9 in the X direction, and the lower part can be displaced in the Y direction by the parallel leaf spring 10 in the Y direction.

Reference numeral 11 denotes a cross spring, which is a cross-shaped leaf spring provided at the top of the parallel leaf spring group 9゜lO. It can be tilted laterally with respect to the vertical axis (Z-axis) and can also be displaced in the Z-axis direction (vertical direction).

A leaf spring assembly (compliance mechanism) that can be displaced in the X, Y, and Z directions is mounted on the wrist between the arm and hand of the robot to absorb positioning errors of the robot.

In addition, by detecting the amount of displacement of each leaf spring body using a force detection device configured by attaching a strain gauge to each leaf spring body that makes up the compliance mechanism, we can detect the magnitude of the reaction force caused by the positioning error of the robot. The robot is driven to counteract this reaction force based on the detection output.

Below, an example of attaching a strain gauge for detecting a reaction force and an example of calculating the reaction force applied to the hand from the output of the strain gauge will be described.

In FIG. 11, 13a, 13b, 13c.

13d are strain gauges (detectors), and cross springs 11
Ma.

It detects Mb, Mc, and Md, and the strain gauge 13
a is for detecting the moment Ma, a strain gauge 13b is for detecting the moment Mb, a strain gauge 13c is for detecting the moment Mc, and a strain gauge 13d is for detecting the moment Md.

The strain gauges 14a and 14b are each a strain gauge, and each
Directional parallel leaf spring9. It is provided on the wall surface of the parallel leaf spring 10 in the Y direction, and is used to detect moments Me and Mf applied to the parallel leaf spring.

As is well known, each strain gauge is constructed by connecting four resistor groups to form a bridge circuit, and detects a moment based on a change in output voltage with respect to input voltage.

In addition, each of these strain gauges 13a to 13d, 14a to 14b
The forces Fx, Fy in the directions of the respective axes X, Y, and Z are applied to the tip of the hand 4 from the output M a y M f.

Fz and the moments Mx and My in the X and Y directions are determined as follows.

Ma = a −F z +My −−−−−−
---(11Mb= a-Fz+Mx ・---
--------(2) Mc= a-Fz-My −
−−−−−−−−−−(3) Md= a−Fz−Mx
・------t4) M e = n-F x
−−−−−−−−−−−−(51Mf=m
-Fy--1-・----------(61 However, a is the center of the cross spring 11 and each strain gauge 13a to
d (see Figure 11), m and n are each parallel leaf spring 9
, 10 and the strain gauge 14a.

14b (see FIG. 11).

Note that in FIG. 11, up to Fz-My represents the force and moment at the upper tip of the connecting rod 12; This is the formula to find the force and moment above.

Therefore, from the above-mentioned equations (11 to (6)), each component of each force vector Fx-Fz, Mx, My is as follows: Fx=Me/n (7)
Fyshi M f / m (
81F z −(Ma +Mb +Mc +Md) /
4 a・−(9)Mx=(Mb−Md)/2−−−
-------...QO1My= (Ma-Mc)/2
−−−−−−−−− (11).

As is clear from Fig. 11, in the conventional compliance mechanism and force detection device as described above, the thickness of each leaf spring body is extremely thin. In such cases, if a large external force is applied, plastic deformation occurs and the detection device is destroyed.

[Prior art]

For this reason, the present applicant has proposed a device that is provided with a limit mechanism for regulating the displacement of the leaf spring body, as shown in, for example, Japanese Patent Laid-Open No. 59-59388.

FIG. 12 is a diagram for explaining a compliance mechanism having a limit mechanism.

In the figure, the force detection device 6 is composed of parallel leaf springs 9a, 9b that are movable in the X direction and parallel leaf springs 10a, 10b that are movable in the Y direction orthogonal to the X direction. Each parallel plate spring 9a, 9b, 10a.

The upper end of 10b is removably fixed to each side of a square common mounting base 16 with screws 15. X direction parallel plate spring 9
The lower ends of a and 9b are fixed to a mounting base 16a with screws 15, and parallel plate springs 10a in the Y direction.

The lower end of 10b is fixed to another mounting base 16b with screws 15. A connecting rod 18 connected to an arm (not shown) located above the force detection device 6 is fixed to a lower end mount 16b of the parallel plate springs 10a, 10b in the Y direction, and this connecting rod 18 is connected to the parallel plate springs 9a, 9b, 10a.

It is connected to the arm through the through hole 16C of the common mounting base 16 at the upper end of the arm 10b. 18a is a screw hole for connection with the arm. X-direction leaf springs 9a, 9b and Y-direction leaf spring 1
0a, 10b are fastened to the respective mounting bases 16, 16a, 16b by screws 15 in order to obtain an arbitrary spring constant by exchanging them.

When a force F is applied to the connecting rod 18 between the wrist and the arm, the X-direction parallel leaf springs 9a,
9b and a parallel plate spring 10a in the Y direction.

10b deforms and absorbs this side F. In this case, since the movable range of the connecting rod 18 is determined by the diameter of the through hole 16c, the displacement of the parallel plate spring is regulated by the through hole 16c.

FIG. 13 is a perspective view of another example. In this example,
The lower end mounting bases 16a, 16b of each of the parallel plate springs 9a, 9b, 10a, 10b are U-shaped as shown in FIG. 14, and each has a U-shaped recess 16a'.

16b'. The mounts 16a and 16b are arranged so that their recesses face each other and are orthogonal to each other so that each mount fits into the recess of the other mount. Width W/ of the recess of each mounting base and width W2 of the mating mounting base that fits into this
The movable range of each mounting base in the X and Y directions is determined by the difference between the two, and the displacement of the parallel leaf spring is regulated. In this example, the lengths Lx and LY of each parallel leaf spring 9a, 9b, 10a, 10b are equal. Therefore, with one type of spring shape,
The same spring constant is obtained in the Y direction.

Incidentally, each force component can be determined by attaching a strain gauge to each leaf spring and calculating the output using each of the above-mentioned formulas.

[Problem that the invention seeks to solve]

However, in the conventional compliance mechanism and force detection device described above, the structure of the limit mechanism is complicated, and calculations such as the above formula must be performed in order to calculate the force component, making it difficult to operate the robot. It is necessary to improve the force detection device for time control.

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the support device of the present invention.

In FIG. 1, a plate-shaped elastic body 2 is supported by a first member 1. As shown in FIG. Reference numeral 3 denotes a displacement regulating means, which faces the displacement direction of the plate-like elastic body 2 (arrow indicated by symbol A in the figure) with a minute gap (within a displacement range in which the plate-like elastic body 2 does not cause plastic deformation). The second member 4 is arranged and supported by the first member 1.

[Effect]

As a means 3 for regulating the displacement of the plate-like elastic body 2, a second member 4 is supported by the first member 1 and is disposed at a minute gap within the elastic deformation range in the displacement direction of the plate-like elastic body 2. Therefore, when an external force is applied to the plate-like elastic body 2 and it attempts to displace excessively with respect to the first member 1, the displacement of the elastic body 2 is regulated by the second member 4, so that the elastic body 2 The body 2 is not plastically deformed.

Therefore, by making the elastic body 2 extremely thin, it is possible to obtain a high S/N ratio even against a minute reaction force within the range of plastic deformation, and at the same time, it is possible to protect against excessive displacement.

〔Example〕

2 and 3 are explanatory diagrams of an embodiment of the support device of the present invention, in which FIG. 2 is a perspective view, and FIG. 3 is an exploded perspective view of FIG. 2.

Also, Fig. 4 is a plan view of the XYZ module, and Fig. 5 is a plan view of the XYZ module.
A side view of the YZ module, and FIG. 6 is a plan view of the γ module.

In the figure, 30 is a force detection module that detects forces in the x, y, and z axis directions, and is a cross-shaped structure composed of square rods 21 and 22 that deform in the three directions of X, Y, and Z. be.

This XYZ module 20 has a slit-like gap a.

a', b, b', c, c' by wire electrical discharge machining 2. .

Parallel leaf spring bodies 23, 24, 25, 26, and 27° 28 are formed on each of the square bars 21 and 22 by forming the rectangular bars 21 and 22, respectively. In addition, in FIGS. 4 and 5, 50, 51,
Reference numerals 52, 53, 54, and 55 are through holes formed in advance by a drill or the like to pass wires for wire electric discharge machining, and are not shown in FIGS. 2 and 3.

Therefore, a slit-like gap a is formed in this XYZ module 20.
, a', b, b', c, c' to form a parallel plate spring body 2.
3 to 28, and at the same time, displacement regulating members 56, 57, 58, 59 for regulating the displacement of this parallel plate spring body.
, 60.61 are formed.

That is, even if each of the parallel leaf spring bodies 23 to 28 is displaced by an external force, the displacement regulating members 56 to 61 are disposed with a minute gap (approximately 3 mm in thickness of the wire), so that the parallel leaf spring bodies 23 to 28 will not be displaced any further. Therefore, even if the plate spring portion is made thin, it will not buckle when an excessive external force is applied.

As is clear from FIGS. 3, 4, and 5, the force detection module 30 has parallel leaf spring bodies 23, 24, 25, 26
, 27 and 28 are provided so that their displacement directions are perpendicular to each other, and the parallel leaf spring bodies 23 and 24 are used to adjust the displacement in the X-axis direction (
Deflection) Deflection in the Y-axis direction by the parallel leaf spring body 25.26,
It has three degrees of freedom in which the parallel leaf spring bodies 27° and 28 respectively share the deflection in the X-axis direction.

Reference numerals 31 and 32 denote supports that support the force detection module 30, respectively. The support 31 is connected to the square bar 22 by a screw 33, and the support 32 is connected to the square bar 21 by a screw 34. Note that only one side of the screws 33 and 34 is shown, and the screw hole 33a into which each screw 33 is screwed and the other hole are the holes 3 and 34.
Similarly, the screw holes 34a and 34b into which the screw 34 is screwed are set at the same distance from the center of the hole 37 (L9=L10).

Reference numeral 35 denotes an output member connected to the support body 31 by a screw 36, and is configured to pass through a hole 37 provided in the force detection module 30.

In this case, the support body 32 is fixed, for example, on a base such as a robot. Incidentally, the support body 32 is fixed to the robot using screws (not shown) that are screwed into the screw holes 32a and 32b.

40a, 40b, 40c, 40d, 40e, and 40f are strain gauges, and each parallel leaf spring body 23, 25, 28
Detect the displacement of

In addition, in order to detect the force in the axial direction without being affected by torque, each strain gauge is attached to each parallel plate spring body 24, 26° 27 so as to be symmetrical about the hole 37. Moreover, each strain gauge is provided so as to constitute a known bridge circuit, and is configured to detect the displacement of each parallel plate spring body.

Here, a method will be described in which the force in each axial direction is detected without the influence of torque by attaching strain gauges to each of the parallel plate spring bodies 23 to 28 so as to be symmetrical about the hole 37.

FIG. 7 is an explanatory diagram of a method for detecting axial force without the influence of torque.

FIG. 7(a) is a diagram showing a state in which a force F in the Y-axis direction is applied to the square bar 21 of the XYZ module 20 shown in FIG. 3, and FIG. 22 is a diagram showing a state in which a force F in a direction of rotation about the center of the hole 37 is applied to the hole 37. FIG.

In the figure, 23 to 26 indicate parallel leaf spring bodies, and 23a
, 23b, 24a, ----26b are leaf springs. 14g, 14h, 14i, 14j are strain gauges,
They are attached so as to be symmetrical to the center line passing through the center of each hole 37. That is, strain gauges 14g and 141,
Strain gauges 14h and 14j are attached to leaf springs 26a and 25b at symmetrical positions about the center point. Note that the resistance value of each strain gauge 14g to 14j is R.

Further, the strain gauges 14g to 14j are connected to their respective output lines (not shown) so as to form a bridge circuit shown in FIG.

Therefore, as shown in FIG. 7(a), when an axial force F is applied, the strain gauges 14g and 14h are in a contracted state, so the resistance value becomes (R-ΔR), and the strain gauge 14i
, 14j are in a stretched state, so the resistance value is (R+ΔR
), so the terminals a-b of the bridge circuit shown in FIG.
The voltage between is (R-ΔR)i-(R+ΔR)i=-2Δ
Ri-(12).

Further, as shown in FIG. 7(b), when a force F in the rotational direction is applied, the strain gauges 14g, 14h and the strain gauge 14
Since both terminals i and 14j are in a contracted state, the voltage between terminals a and b becomes (R-ΔR)i-(R-ΔR)i=O-(13).

Therefore, by attaching the strain gauges 14g to 14j as shown in Fig. 7 and configuring a bridge circuit as shown in Fig. 8, it is possible to detect only the force in the axial direction without being affected by torque. .

Although the above description only deals with the case of one axis (Y-axis), it can be attached to the leaf springs 23b and 24b in the same way, or it can be attached to the leaf spring body 28.27 (Fig. 3). By doing so, forces in the XYZ axis directions can be detected without the influence of torque.

That is, although only the strain gauges 403 to 40f are shown in FIG. 3, the strain gauges are actually attached so that the hole 37 is the center point and is at a target position.

Further, in FIG. 3, 41 is a γ module for detecting torque around the Z axis, and the force detection module 3
It is attached to the output rod 35 of No. 0 through the center member 42 with a screw 39.

The T module 41 includes a disc-shaped member 4 as shown in FIG.
By forming slit-like gaps a, b, c, and d in the plate springs 41a, 41b, and 4 by wire electric discharge machining, the plate springs 41a, 41b, and 4
1c and 41d are formed.

Also, like the XYZ module, through holes 62 and 63 are formed for passing wires for electrical discharge machining. (3rd
(not shown) Therefore, at the same time as the leaf springs 41a to 41d are formed, displacement regulating members 64, 65, 66, and 67 for regulating the displacement of the leaf springs 41a to 41d are formed.

Incidentally, reference numerals 68 and 69 are escape holes, which are formed during wire electrical discharge machining, and are connected to the strain gauges 44a and 44.
This is to make it easier to attach 44 c, 44 d.

As is clear from FIG. 3, strain gauges 44a to 44d
is the leaf spring 41a with the center point of the center member 42 as the target position.
, 41b are attached on the same side.

By attaching the strain gauge in this manner, the torque around the shaft can be detected independently without the influence of axial force.

This will be explained using FIG. 9.

FIG. 9 is an explanatory diagram of a method for detecting torque around an axis without being affected by axial force.

Note that this example will be explained using the XYZ module 2o.

In FIG. 9, parts that are the same as those in FIG. 7 are given the same numbers and their explanations will be omitted. The difference from FIG. 7 is that the strain gauges 14i and 14j are attached to the leaf spring 25a, that is, the strain gauges 14g to 14j are attached to the same side of the leaf spring. Also, each strain gauge 1
4g to 14j are attached at the same distance from the center point.

Furthermore, the strain gauges 14g to 14j constitute a bridge circuit as shown in FIG.

Therefore, when an axial force F is applied as shown in FIG. 9(a), all strain gauges 14g-14j are in a contracted state, so the voltage between terminals a and b is (R-ΔR). i-(
R-ΔR)i =0-(14).

Similarly, as shown in FIG. 9 (bl), when the force F around the axis is applied, the strain gauges 14g and 14h are in a contracted state, and the strain gauges 14i and 14j are in an extended state, so that the The voltage is (R-ΔR)i-(R+ΔR)-2ΔRi-(15)
becomes.

Therefore, it is possible to independently detect the force around the axis, that is, the torque, without being affected by the force in the axial direction.

In the above description, the reason why the strain gauges are placed at equal distances from the center point is to ensure that the same voltage value is obtained for the same force. In other words, if the distance is different, the amount of displacement of the leaf spring will be different, and therefore the output voltage will be different.

Note that the γ module 41 is attached to the output rod 35 using only screws 39 at the center of the output rod 35, but in this configuration, when torque is applied to the outer ring 43, the screws 39 may loosen. In reality, it is necessary to engage the pin protruding from the center member 42 with the output shaft 35 to prevent rotation, and to fix it with the screw 39 at a position deviated from the center position.

Further, this also applies to the case of coupling the output shaft 35 and the support body 32. Also, 43a, 43b, 43c, 4
The screw hole indicated by 3d is for attaching a hand.

With this configuration, when the center member 42 is circumferentially defined and a torque around the center axis (Z axis) is applied to the disc-shaped member 43, the leaf springs 41a, 41b, 41c are formed.

41d is deflected. This deflection is measured by the strain gauge 44a.

By detecting at 44b, 44c, and 44d and taking out the output via the bridge circuit, only the torque related to the Z axis (γ) can be detected.

As explained above, according to this embodiment, it is possible to obtain a force detection device in which force components can be obtained independently and the structure of the limit mechanism is simple.

According to the embodiment described above, a limit mechanism can be obtained with a simple configuration, but in the case of an XYZ module,
As is clear from FIGS. 4 and 5, the displacement of each leaf spring is regulated by the contact between the tip portions of the displacement regulating members 56 to 61 and the portion of each leaf spring on the hole 37 side. It is.

Therefore, symbols B, B', and D in FIGS. 4 and 5.

D', H, H', I, I', J, J
Since the external force is concentrated in the arrowed areas indicated by ', K, and K', reducing the thickness of the leaf spring has the disadvantage that it is more likely to buckle.

An example of a support device that can overcome these drawbacks will be described below.

FIG. 10 is a diagram for explaining another embodiment of the present invention.

In the figure, 24a and 24b are leaf springs, and 56 is a displacement regulating member. a is a slit-like gap, which is formed by wire electrical discharge machining.

Here, when forming the slit-like gap a by wire electric discharge machining, L
Leaf springs 24a, 24 that form a character-shaped portion and on which external force is concentrated
Increase the thickness of each portion of b and D'.

As is clear from FIG. 10, the external force causes the leaf spring 24a to
, 24b are displaced, the leaf spring 24a.

Since the thickened portion D' of plate spring 24b comes into contact with displacement regulating member 56, plate springs 24a and 24b are unlikely to buckle.

In this embodiment, the slit-like gap a is an L-shaped part, or M, but it is not necessarily limited to this, and may be diagonal.

Further, in this embodiment, only the leaf springs 24a and 24b are explained, but it goes without saying that the present invention can also be applied to other leaf springs of the XYZ module shown in FIGS. 4 and 5.

〔Effect of the invention〕

As explained above, according to the present invention, a limit mechanism can be realized with a simple configuration.

[Brief explanation of drawings]

Figure 1 is a block diagram of the principle of the present invention, Figure 2 is a side view of the actual module, Figure 6 is a plan view of the T module, Figure 7 is an explanatory diagram of the axial force detection method, and Figure 8 is the bridge. Explanatory diagram of the circuit,
Fig. 9 is an explanatory diagram of a method for detecting force around an axis, Fig. 10 is an explanatory diagram of another embodiment, and Figs. 11, 12, 13, and 14 are explanatory diagrams of a conventional example. . In the figure, 1 is a first member, 2 is a plate-like elastic body, 3 is a displacement regulating means, and 2 is a member.

Claims (1)

[Claims] (1) A support device comprising a first member (1) that supports a plate-shaped elastic body (2) and a displacement regulating means (3) that regulates displacement of the plate-shaped elastic body (2). The displacement regulating means (3) is supported by the first member (1) and is opposed to the plate-shaped elastic body (2) in the displacement direction with a minute gap within the elastic deformation range of the elastic body. A support device characterized in that it is constituted by a second member (4) that is arranged.