JPS6254692A - Wrist mechanism of industrial 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 [Field of Industrial Application] The present invention relates to a wrist mechanism for an industrial robot, and more particularly to an improvement in a wrist mechanism that allows the forearm of an articulated robot to move about three axes.

[Prior art and its problems]

Conventionally, as shown in FIG. 3, a first wrist part 2 is supported by the distal end of a forearm l of a robot and is rotatable around a longitudinal axis γ of the forearm; a second wrist portion 3 supported by the second wrist portion 3 and rotatable around an axis β perpendicular to the axis T; a second wrist portion 3 supported by the second wrist portion 3 rotatable around an axis α perpendicular to the axis β; third wrist part 4
An industrial robot head mechanism equipped with the following is known.

In this type of conventional wrist mechanism, when the wrist posture is such that the axis γ and the axis α are located in the same plane, the axis α
and axis T are parallel. That is, the rotational axis α of the third wrist portion 4 is offset from the longitudinal axis γ of the robot arm 1.

A wrist mechanism having such a configuration has the disadvantage that the coordinate transformation equation for controlling its posture is a nonlinear equation, making the control complicated.

[Means for solving problems]

As a means for solving the above problems, the present invention provides a first wrist portion whose base end is supported by a forearm of a robot and is rotatable around a longitudinal axis γ of the forearm; a second wrist supported by the distal end of the wrist and rotatable around an axis β perpendicular to the longitudinal axis T of the forearm; Rotation axis β
and a third wrist portion rotatable around an axis α perpendicular to the first wrist portion, the first wrist portion forming a predetermined angle with respect to the longitudinal axis γ of the forearm from its base end to its distal end. The third wrist portion is disposed so that the axis of rotation α thereof and the longitudinal axis γ of the forearm are coaxial when they are in the same plane, and the third wrist portion is arranged such that the axis of rotation α and the longitudinal axis γ of the forearm are coaxial. A hollow shaft for transmitting rotational driving force to the second wrist portion and an inner shaft for transmitting rotational driving force to the third wrist portion are rotatably provided around the longitudinal axis C of the first wrist portion. A wrist mechanism for an industrial robot is provided.

[For production]

According to the above measures according to the invention, the longitudinal axis T of the forearm
When the wrist posture is such that the axis α and the rotation axis α of the third wrist part are located in the same plane, the axis α and the axis T become coaxial, so the coordinate transformation equation for controlling the posture of the wrist mechanism is a linear equation. This makes control easier. Moreover, the first wrist portion extends along the longitudinal axis γ of the forearm from its base end to its distal end.
The first wrist part includes a hollow shaft for transmitting rotational driving force to the second wrist part and an inner ring for transmitting rotational driving force to the third wrist part. Since it is rotatably provided around the longitudinal axis C of the first wrist part, it is possible to prevent an increase in the number of rotational power transmission elements for transmitting rotational driving force to the second wrist part and the third wrist part. .

These and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

〔Example〕

1 and 2 show one embodiment of the present invention. First, referring to FIG. 2, the industrial robot includes a base 11 having a reference installation surface, and a rotating body 12 supported by the base 11 and rotatable around an axis θ perpendicular to the reference installation surface. ing. A base end portion of an upper arm 13 is rotatably supported by the swing body 12 around an axis W perpendicular to the axis θ. A forearm 14 is supported at the distal end of the upper arm 13 so as to be rotatable around an axis vAU parallel to the axis W.

A proximal end portion 16 of a first wrist portion 15 is rotatably supported on the forearm 14 around the longitudinal axis γ of the forearm 14 . The first wrist portion 15 extends from its base end 16 to its distal end 17 in a direction forming a predetermined angle φ with respect to the axis γ. 1st
A second wrist portion 18 is rotatably supported on the distal end portion 17 of the wrist portion 15 around an axis β perpendicular to the axis γ. A third wrist portion 19 is rotatably supported by the second wrist portion 18 around an axis α perpendicular to the axis β.

Within the first wrist portion 14, the base end portion 1 of the first wrist portion 15
6 has a gear 20 fixed to it, and a gear 22 that meshes with this gear 20 is fixed to the output shaft of a drive motor 21 attached to the forearm 14. Therefore, the first wrist portion 15 is rotationally driven around the longitudinal axis γ of the forearm 14 by the operation of the drive motor 21 .

A hollow shaft 23 is rotatably supported within the first wrist portion 15 around the longitudinal axis C of the first wrist portion 15 . An inner shaft 24 is rotatably supported within the hollow shaft 23 around an axis C. A hollow shaft 25 is provided within the forearm 14 so as to be rotatable around the axis γ, and an inner shaft 2 is provided within the hollow shaft 25.
6 is rotatably provided around the axis T.

In the forearm 14 , a gear 27 is fixed to the base end of a hollow shaft 23 that is pivotally supported by the first wrist portion 15 , and this gear 27 is connected to a gear 28 fixed to an inner shaft 26 in the forearm 14 . They mesh together. A toothed pulley 29 is fixed to the inner shaft 26. Drive motor 30 attached to forearm 14
A toothed pulley 31 is fixed to the output shaft of the timing belt 3 as an endless cable.
They are connected via 2. Therefore, the hollow shaft 23 supported by the first wrist portion 15 is rotationally driven around the axis wAC by the operation of the motor 30.

In the forearm 14 , a gear 33 is fixed to the base end of an inner ring 240 that is pivotally supported by the hollow shaft 23 in the first wrist part 15 . It meshes with gear 34. A toothed pulley 35 is fixed to the hollow shaft 25. A toothed pulley 37 is fixed to the output shaft of a drive motor 36 attached to the forearm 14, and both pulleys 35, 37 are connected via a timing belt 38 as an endless cable.

Therefore, the inner shaft 24, which is pivotally supported by the hollow shaft 23 in the first wrist portion 15, is driven to rotate around the axis C by the operation of the motor 36.

In the illustrated embodiment, gears 27.33 are spur gears and gears 28.34 are bevel gears.
Gear 27.33 is a bevel gear, and gear 28.3
4 may be a spur gear.

A bevel gear 39 is fixed to the distal end portion of the hollow shaft 23 within the distal end portion 17 of the first wrist portion 15 . The bevel gear 39 is connected to the second wrist portion 18 via a bevel gear 40 and a speed reducer 41 that are rotatably provided around the axis β. Therefore, the rotation of the hollow shaft 23 is transmitted to the second wrist portion 18 via the bevel gear 39, 40 and the reducer 41.

In the distal end portion 17 of the first wrist portion 15 , a bevel gear 42 is fixed to the distal end portion of an inner shaft 24 that is pivotally supported by the hollow shaft 23 . A shaft 43 extending through the bevel gear 40 and the reducer 41 is rotatably provided around the axis β. A bevel gear 44 that meshes with a bevel gear 42 is fixed to the shaft 43 within the distal end 17 of the first wrist portion 15 .

Furthermore, a bevel gear 45 is fixed to the shaft 43 within the second wrist portion 18 . The bevel gear 45 is connected to the third wrist portion 19 via a bevel gear 46 and a reducer 47. Therefore, the rotation of the inner shaft 24 is controlled by the bevel gear 42.
．． 44-46. and the third wrist portion 19 via the reducer 47
transmitted to.

In the wrist mechanism configured as described above, the third wrist portion 19 is arranged so as to be coaxial when the rotational axis α and the longitudinal axis T of the forearm 14 are in the same plane. Therefore, the coordinate transformation equation for posture control of the wrist mechanism becomes a linear equation, which simplifies the control.

In addition, the first wrist portion 15 extends from its base end portion 16 to its distal end portion 17.
at a predetermined angle φ with respect to the longitudinal axis T of the forearm 14.
The first wrist portion 15 includes a hollow shaft 23 for transmitting rotational driving force to the second wrist portion 18 and a third
Since an inner ring 24 for transmitting rotational driving force to the wrist portion 19 is rotatably provided around the longitudinal axis C of the first wrist portion 15, rotational force is transmitted to the second wrist portion 18 and the third wrist portion 19. This makes it possible to prevent an increase in the number of rotary power transmission elements for transmitting driving force. That is, for example, the hollow shaft 2
3 and the inner shaft 24 are arranged parallel to the longitudinal axis T of the forearm 14, the hollow shaft 23 and the inner shaft 24 in the first wrist part 15 and the hollow shaft 25 and the inner shaft 26 in the forearm 14. It becomes difficult to connect the two using only one pair of gears, and power transmission using an endless cable or the like becomes necessary. Additionally, the wrist mechanism will also be larger. However, as described above, in the wrist mechanism configured as described above, the hollow shaft 23 in the first wrist portion is connected to the inner shaft 26 in the forearm 14 via a pair of gears 27, 28, and inner shaft 24 of
The hollow shaft 2 in the forearm 14 via a pair of gears 33 and 34
5, the number of power transmission elements can be minimized and the wrist mechanism can be downsized.

Although one embodiment has been described above, the present invention is not limited only to the aspect of the above embodiment.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, when the wrist posture is such that the longitudinal axis γ of the forearm and the rotational axis α of the third wrist portion are located in the same plane, the axis α and the axis γ
Since these are coaxial, the coordinate transformation equation for posture control of the wrist mechanism becomes a linear equation, which simplifies control. Moreover, the first wrist part extends from its base end to its distal end in a direction forming a predetermined angle with respect to the longitudinal axis T of the forearm, and a rotational driving force is transmitted to the second wrist part within the first wrist part. Since the hollow shaft for transmitting rotational driving force to the third wrist portion and the inner ring for transmitting rotational driving force to the third wrist portion are rotatably provided around the longitudinal axis C of the first wrist portion, the second wrist portion and the third wrist portion This makes it possible to prevent an increase in the number of rotational power transmission elements for transmitting rotational driving force to the. Therefore, it is possible to provide a wrist mechanism for an industrial robot with easy posture control and a simple structure.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a wrist mechanism of an industrial robot showing an embodiment of the present invention, Fig. 2 is an overall side view of an articulated robot equipped with the wrist mechanism shown in Fig. 1, and Fig. 3 is a conventional FIG. 3 is a side view showing the wrist mechanism of the industrial robot. 14...Forearm, 15...First wrist part, 16...Proximal end of the first wrist part, 17...Distal end part of the first wrist part, 18...Second wrist part, 19 ...Third wrist portion, 23...Hollow shaft, 24...Inner shaft.

Claims (1)

[Claims] 1. A first wrist portion whose base end portion is supported by the forearm of the robot and is rotatable around the longitudinal axis (γ) of the forearm, and a distal end portion of the first wrist portion. a second wrist part supported by the forearm and rotatable around an axis (β) perpendicular to the longitudinal axis (γ) of the forearm;
a third wrist part that is rotatable around an axis (α) perpendicular to the rotational axis (β) of the wrist part, and the first wrist part extends in the longitudinal direction of the forearm from its base end to its distal end. The third wrist portion extends in a direction forming a predetermined angle with respect to the axis (γ), and the third wrist portion is coaxial when the rotation axis (α) and the longitudinal axis (γ) of the forearm are in the same plane. A hollow shaft for transmitting rotational driving force to the second wrist portion and an inner shaft for transmitting rotational driving force to the third wrist portion are arranged in the first wrist portion. 1. A wrist mechanism for an industrial robot, characterized in that it is rotatably provided around a longitudinal axis (C) of a wrist portion. 2. The hollow shaft and the inner shaft are each connected to a rotational drive device via a gear mechanism provided within the proximal end of the first wrist, and the hollow shaft is connected to a rotational drive device within the distal end of the first wrist. The inner shaft is connected to the second wrist part through a gear mechanism provided in the first wrist part, and the inner shaft is connected to the gear mechanism provided in the distal end of the first wrist part and the gear mechanism provided in the second wrist part. The wrist mechanism for an industrial robot according to claim 1, wherein the wrist mechanism is connected to the third wrist portion via.