JPH02279293A - Speed reducing mechanism for robot - 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 [Industrial Field of Application] The present invention is directed to a reduction gear for a robot that is compact in shape yet has a large reduction ratio.

[Prior Art] Conventionally, a single-section mechanism for a robot is required to be compact, so a harmonic drive reduction gear is often used.

FIG. 5 is a configuration diagram showing a joint structure of a robot using a harmonic drive reducer, as shown on page 82 of "Mechanical Element Design Guidebook" published by Taiga Publishing Co., Ltd., for example. In the figure, (1) is a rotating machine, and (2) is a harmonic machine.
Tsukdrive reducer, (9) is the one-section support, (10) is the robot arm, (11) is the robot arm axis that is the rotation axis of the robot arm (10), (6) is the reduction gear 11 (2
) is a one-bar bearing that supports the robot arm shaft (11), which is the output shaft of the robot arm (11).

Next, the operation will be explained. The rotation axis of rotation*(1) is
Human power is applied to the human power shaft of the harmonic drive reducer (2), which is a reducer, and this harmonic drive reduces the speed by 1 m (2 m).
) is connected to the robot arm shaft (11) supported by the one-node bearing (6), so the rotation 11 (1)
By rotating the robot arm (' 1.0
) is driven.

[Problem to be solved by the invention] Conventional robot reduction mechanisms have been configured as described above, but on the other hand, harmonic drive reduction gears have the disadvantage of low torsional rigidity between the human power shaft and the output shaft. Because there is
The problem is that the deceleration mechanism tends to resonate with rapid movements of the robot arm, and to avoid this resonance, the control band for position control needs to be about 1/2 to 1/3 of the resonant frequency. There was a point.

This invention was made to solve the above-mentioned problems, and aims to provide a deceleration mechanism for a robot that can prevent resonance from occurring, expand the robot's position control band, and increase the speed of the robot. purpose.

[Means for Solving the Problems] The robot speed reduction mechanism of the present invention includes a first and second speed reducer that are connected to the rotating shaft of a rotating machine and have an equal speed reduction ratio, and are attached to the output shaft of the first speed reducer. and a damper load that adds a moment of inertia, a robot arm attached to the output shaft of the second reducer, and a damper that connects the damper load and the robot arm, and the resonance between the first reducer and the damper load is reduced. The frequency is set higher than the resonance frequency of the second reduction gear and the robot arm.

[Function] In the robot speed reduction mechanism of the present invention, the frequency of resonance (abbreviated as first resonance) generated by the first reduction gear and the damper load attached to it is controlled by the frequency of the resonance (abbreviated as first resonance) generated by the first reduction gear and the damper load attached to it. By setting the frequency higher than the resonance (abbreviated as second resonance) that occurs in the robot arm, the damper load will generate vibration even when the second resonance occurs and the robot arm is vibrating. do not. If this damper load and the robot arm are connected by a damper, damping will act on the vibration at the resonant frequency of the robot arm, and the resonance will be attenuated.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional configuration diagram showing one section of a robot to which a robot reduction mechanism according to an embodiment of the present invention is applied. In the figure, (1) is a rotating machine, and (la) is a rotating machine (1). shaft, (2) is the first reducer, (3) is the second reducer, (
4) is a robot arm (8) to effect damping.
), that is, a damper load that adds 1 moment of inertia, (5) is a damper, in this case a disc-shaped rotary damper, and (6) supports the rotating shaft (Ia) of rotating machine (1). (7) is the damper load bearing that supports the damper load rR (4), (8) is the robot arm (10)
), (9) is the opening support, and (lO) is the robot arm. In this case, the first and second reducers (2) and (3) are reducers with equal reduction ratios having a human power shaft penetrating through the center, for example, a zero-rotation machine bearing (6 )
The rotating shaft (ta) supported by is connected to the through-type human power shafts of the first reducer (2) and the second reducer (3),
The fixed side disks of both reducers are each fixed to the opening support part (9). The output shaft of the first speed reducer (2) is connected to a damper load (4) supported by a damper load bearing (7). The output shaft of the second reducer (3) is connected to the robot arm (10), and the robot arm (lO) and damper load (4) are coupled by a disc-shaped rotary damper (5). At this time, the frequency of resonance generated by the first reducer (2) and the damper load (4) is the same as that of the second reducer (3).
) and the robot arm (lO) are designed to have a higher frequency than the resonance that occurs.

In this case, the moment of inertia is optimized by appropriately changing the material and shape of the damper load (4).

FIGS. 2(a) and 2(b) show the structure of the rotary damper (5), and FIG. 2(a) is a partially cutaway top view showing the inside;
Figure (b) is a cross-sectional view taken along the nb-nb line in figure (a), where the left side is a cross-sectional view seen from the entrance direction, and the right side is a cross-sectional view seen from the B direction. is an orifice disk with orifices arranged radially on the disk, (5b
) is a partitioned disk with partitions similarly placed on the disk. In FIG. 2(a), a cross section of the partition disk 5b) with the disk section removed is shown, in order to show the structure of the orifice disk (5a) and the partition circle 1k (5b), and the part visible from the cutout. Of these, the hatched portion is the remaining partition portion on the partition disk (5b) side, and the other portion is the orifice disk 5a).

Next, by driving the zero-rotation machine (1), the operation of which will be explained, the rotating shaft (ta) rotates, and the first reduction gear (2) rotates.
The rotation is manually applied to the second reducer (3), and the damper load (4) and robot arm (10) connected to the respective output shafts rotate.

Since the above two reducers (2) and (3) have the same reduction ratio, the damper load (
4) and the robot arm (10) operate at the same rotation angle, and the rotary damper (5) does not function. When the drive frequency approaches the resonant frequency of the robot arm (10) and the second reducer (3), if there is no rotary damper (5), the robot arm (10) side will vibrate, but the damper load will be reduced. (
Since the resonance frequency on the 4) side is designed to be higher than that on the robot arm (10) side, no vibration occurs. The rotary damper (5) is, for example, a partition circle as shown in Figure 2! 1i1
(5b) and orifice circle 11 (5a),
A viscous fluid such as machine oil is sealed inside. By combining the two disks (5a) and (5b), a structure is created in which partitions and orifices are alternately arranged between the two disks (5a) and (5b), and a viscous fluid is sealed in this structure. As a result, the respective partitions and the orifice move relative to each other, creating viscous resistance when the viscous fluid passes through the orifice, so that the whole acts as a rotational damper against the relative movement of the two discs.

By connecting the damper load (4) and the robot arm (10) with this rotary damper (5), the damper load (4) and the robot arm (10) described below are generated near the resonance frequency of the robot arm (4). ) damping acts on the relative motion of the robot arm (4) and suppresses the photographing motion of the robot arm (4).

Therefore, according to this embodiment, since damping acts on the vibration of the robot arm to suppress the vibration, the control band for position control is set to 172 to 1/1/2 of the resonant frequency in order to avoid resonance.
It does not have to be limited to about 3, and the control band for position control can be brought closer to the resonance frequency compared to conventional speed reduction mechanisms, so the operation band for position control can be expanded and the robot can be made faster.

FIG. 3 is a cross-sectional configuration diagram showing a joint of a robot to which a robot deceleration mechanism according to another embodiment of the present invention is applied. In this figure, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. In the embodiment shown in FIG. 3, the two harmonic drive reducers (2) and (3) in FIG.
C), a reduction mechanism that is an integrated mechanism and has two output shafts with the same reduction ratio, consisting of a first output circular spline 2d), a second output circular spline (2e), and a fixed side circular spline (2f) are using. This reduction mechanism includes a cup-shaped harmonic drive (consisting of a wave generator (2a), a cup-shaped flex spline (2b), and a first output circular spline (2d)) which is a first reduction gear; The second reduction gear is a flat type harmonic drive (wave generator (2a), a flat type flex spline (2C)
), a second output circular spline (2e), and a fixed side circular spline (2f)). However, a common wave generator (
By rotating the rotating shaft (1a) connected to 2a), the first output circular spline (2d) and the second output circular spline (2e) rotate at the same reduction ratio. In addition, the rotary damper (5) is the first
A cylindrical type is used instead of the disk type shown in the figure, and its structure is a combination of an orifice cylinder (5a) and a partition cylinder (5b), as shown in the partially cutaway top view of Figure 4. This damper functions in the same way as the rotary damper in the embodiment shown in Fig. 1, and damps the relative motion between the damper load (4) and the robot arm (10) that occurs near the resonance frequency of the robot arm (4). This acts to suppress vibrations of the robot arm (4). Therefore, in this other embodiment as well, the position control band can be expanded and the robot can be operated at high speed.

Note that even if the resonant frequency of the first reducer and damper load is lower than the resonant frequency of the second reducer and robot arm,
Although resonance can be prevented from occurring, it is not practical.

[Effects of the Invention] As described above, according to the present invention, the first and second reducers having the same reduction ratio are connected to the rotating shaft of the rotating machine, and the first and second reducers are connected to the output shaft of the first reducer. , a damper load that adds a moment of inertia, a robot arm attached to the output shaft of the second reducer, a damper that connects the damper load and the robot arm, and a reduction mechanism for the robot, and the first reduction gear and Since the resonance frequency of the damper load is set higher than the resonance frequency of the second reducer and the robot arm, it is possible to prevent resonance from occurring, expand the robot's position control band, and increase the speed of the robot. be.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an opening of a robot to which a robot reduction gear according to an embodiment of the present invention is applied; FIG. 2(a);
(b) shows the structure of the rotary damper in Fig. 1, and (a
) is a partially cutaway top view, (b) is a side cross-sectional view 11i, FIG. 3 is a cross-sectional configuration diagram showing an opening of a robot to which a robot deceleration mechanism of another embodiment of the present invention is applied, and FIG. is the third
Partially cutaway top view showing the structure of the rotary damper in Figure 5.
The figure is a configuration diagram showing a one-section structure of a conventional robot using a harmonic drive reducer. In the figure, (1) is a rotating machine, (1a) is a rotating 11F (
1) rotating shaft, (2) first reducer, (3) second reducer, (4) damper load, (5) rotating damper, (
10) is a robot arm. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] First and second reducers with equal reduction ratios are connected to the rotating shaft of the rotating machine, a damper load is attached to the output shaft of the first reducer and adds a moment of inertia, and the output of the second reducer A robot arm attached to a shaft, a damper connecting the damper load and the robot arm, and the resonance frequency of the first reducer and the damper load is set higher than the resonance frequency of the second reducer and the robot arm. A reduction mechanism for robots.