JPH05253882A - Robot having wrist of three degrees of freedom - Google Patents

Abstract

PURPOSE:To use as a power source an actuator such as a motor with a relatively small output horsepower or torque as well as a light weight to minimize rotational errors caused by the backlash of bevel or spur gears in a transmission or the clearance of a bearing part, to increase the rigidity of transmission parts and reduce the weight of a wrist system, and to simplify equations for determining operation paths. CONSTITUTION:An upper arm part 104 consists of a wrist drive part 4 and a wrist part 1. In the wrist drive part 4, a torsion shaft 16a is provided for an actuator 12a via a first speed reducer, a bending shaft 16b is provided for an actuator 12b via a first speed reducer 13b, and a rotation shaft 16c is provided for an actuator 12c via a first speed reducer 13c. Shafts 16a, 16b, 16c are provided concentrically. The torsion shaft 16a is linked with the wrist part 1 via a second speed reducer 15 and the bending shaft 16b and the rotation shaft 16c are also linked with the wrist part 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wrist mechanism of an industrial robot, and more particularly to a mechanism for transmitting power.

[0002]

2. Description of the Related Art As a wrist mechanism of this type, an actual flat head 02-
In the 150189 publication, reduction gears are provided immediately in front of the swing case and the tool holder to reduce the influence of backlash, and the wrist body is separated from the robot arm to improve maintainability. There is a disclosure. However, since the operating axes do not intersect at one point, the calculation formula becomes complicated, the amount of calculation is large, and the positioning accuracy is adversely affected.

According to the disclosure of Japanese Patent Laid-Open No. 60-44291, a reduction gear having a high reduction ratio is incorporated in the wrist casing.
The reduction of the positioning accuracy due to the downsizing and weight reduction of the transmission shafts and gears of the wrist device and the backlash of the gears is suppressed as much as possible, and the interference of the mutual movements of the degrees of freedom can be ignored. However, the output torque of the motor is controlled with respect to the load inertia of gears, chains, or timing pulleys from the motor output shaft to the reducer, and power transmission components such as the power transmission shaft. -Because the output shaft of the motor does not increase with the reducer, insufficient horsepower is likely to occur. There is no choice but to increase the size of the motor. Further, ignoring the interference of the movements between the degrees of freedom reduces the reliability and repeatability of the movement path. Therefore, it is not suitable for high precision and complicated processing or assembly work.

In Japanese Utility Model Laid-Open No. 59-151693, a reduction gear shaft having an axis orthogonal to the arm axis is provided in the wrist.
A pair of differential reduction gears are mounted symmetrically, and an arm is passed through the drive shaft for adjusting the angle of the wrist and rotating the tool at high speed.
This is the disclosure that the axis is thinned, the arm is downsized, and the operation accuracy is improved. This is disclosed in JP-A-60-
Similar to the one disclosed in Japanese Patent No. 44291, the load inertia of the power transmission component from the drive unit to the speed reducer,
Lack of horsepower is likely to occur. When the diameter of the shaft that transmits high-speed rotation is reduced, vibration is generated due to the decrease in rigidity, and the positioning accuracy deteriorates.

[0005]

An actuator such as a light motor having a relatively small output horsepower or output torque is used as a power source, and a bevel gear of a power transmission mechanism is used.
To provide a structure that reduces rotation errors due to backlash of spur gears and the clearance of bearings, increases the rigidity of power transmission components and reduces the weight of the wrist system, and simplifies the calculation formula for determining the operation path. With the goal.

[0006]

In a robot having a wrist with three degrees of freedom including an upper arm portion, an upper arm driving portion, a lower arm driving portion, and a turning portion, an upper arm portion 104 includes a wrist driving portion 4 and a wrist portion 1, The wrist drive unit 4 is provided with a torsion shaft 16a on the actuator 12a via the first speed reducer 13a and a bending shaft 16b on the actuator 12b via the first speed reducer 13b.
And a rotary shaft 16c is provided on the actuator 12c through the first speed reducer 13c, and the shafts 16a, 16b, 16c are provided.
Are provided concentrically, the torsion shaft 16a is connected to the wrist portion 1 via the second reduction gear 15, the bending shaft 16b and the rotating shaft 16c are connected to the wrist portion 1, and the bending shaft 16b and the wrist portion 1 are connected to each other. The connection is made via the second speed reducer 32 of the wrist 1 and the rotation shaft 16c.
The wrist 1 is connected to the second speed reducer 54 of the wrist 1.
Through the second speed reducer 32 with respect to the axis of the torsion shaft 16a.
That is, the operating point 70 is created by making the axes of the two and the axes of the second speed reducer 54 orthogonal to each other.

[0007]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 is an overall view of a robot body of the present invention, FIG. 2 is a view taken along the line AA of FIG. 1, FIG. 3 is a sectional view taken along the line BB of FIG. 1, showing a wrist driving actuator unit, and FIG. The detail of a wrist mechanism is shown in the CC sectional view of FIG.

The robot body 100, as shown in FIG.
Swivel unit 101, upper arm drive unit 102, lower arm drive unit 103,
It consists of the upper arm 104. The swivel shaft portion 101 is built in the base 9, the upper arm drive portion 102 on the base 9 is a motor 7 and an upper arm actuating parallel link mechanism 6, and the lower arm drive portion 103 is a motor.
It consists of an arm 8 and a lower arm 5. Upper arm 104 and wrist 105
Is a wrist drive unit that is tiltably supported and connected to the drive units 102 and 103 by connecting pins 10 and 11 on upper portions of the upper arm drive unit 102 and the lower arm drive unit 103, and is pin-connected to the connection pin 11 of the parallel link mechanism 6. 4, a casing 3, which is provided in front of the wrist drive unit 4 and is pin-connected to the connecting pin 10 of the lower arm 5,
It comprises an arm 2 projecting from the thing 3 and a wrist 1 projecting from the arm 2.

The wrist drive unit 4 is a motor 12 for driving a torsion shaft.
a and a reduction ratio 1/11 protruding from the output shaft of the motor 12a
Of the first reduction gear 13a, a spur gear (not shown) provided on the output shaft of the reduction gear 13a, and a second reduction gear 15 that meshes with the spur gear (not shown) and has a reduction ratio of 1/10. Spur gear 14a provided on the input shaft of the motor and the bending shaft driving motor 1
2b and the reduction ratio 1/1 protruding from the output shaft of the motor 12b
No. 1 first reduction gear 13b, a spur gear provided on the output shaft of the first reduction gear 13b, and a rotary shaft driving motor 12
c, and a reduction ratio 1/1 protruding from the output shaft of the motor 12c
The first speed reducer 13c is the first speed reducer 13c.

In the embodiment, the servo motor is used as the actuator, but it is also possible to use a pulse motor or a hydraulic motor, and the power transmission by the spur gear is a timing pulley. A timing belt system or a chain and sprocket wheel system can be used instead. Although the second reduction gear 15 is used for the torsion shaft, the torsion shaft driving motor 12a is used.
Even if a mechanism for adjusting the backlash of the spur gear is added to the spur gear section without using the second reducer 15, the speed is reduced by a predetermined ratio with a speed reducer provided on the output shaft of the second embodiment. The performance of is obtained.

Inside the arm 2, the three power transmission shafts of the wrist mechanism 1 are provided concentrically with the x1 axis, and the outermost is a torsion shaft 16a, which penetrates the casing 3 and the casing 3 twists the shaft. 16a is rotatably supported. One end of the torsion shaft 16a is connected to the second speed reducer 15, and the other end is provided with the wrist mechanism 1 in a protruding manner. The middle is the bending shaft 12b, one end penetrates the second reduction gear 15,
The spur gear 14b is projected and meshes with the projected spur gear on the output shaft of the first speed reducer 13b.

At the other end, a bevel gear 21 is provided so as to project in the bending shaft casing 60. The innermost side is the rotating shaft 16c, one end of which is connected to the output shaft of the first speed reducer 13c protruding from the output shaft of the rotating shaft driving motor 12c, and the other end of which is a bevel gear in the bending shaft casing 60. 41 is projected. The wrist mechanism 1
It operates with the x1 axis as the axis of the twisting axis, the y0 axis as the axis of the bending axis, and the x0 axis as the axis of the rotating axis.
Cross at 0.

FIG. 4 shows the wrist mechanism 1 in detail. It consists of power transmission parts for the bending shaft and rotating shaft. The bending shaft 16b is rotatably supported around the x1 axis inside the hollow torsion shaft 16a, and the bevel gear 21 projecting from the bending shaft 16b has a shaft 24 having a y1 axis orthogonal to the x1 axis as a rotation axis. It meshes with the fitted bevel gear 22. One end of the shaft 24 is rotatably supported by a bending shaft casing 60, the other end penetrates the bevel gear 42, and a spur gear 26 is provided in a protruding manner.

The rotary shaft 16c, like the shafts 16a and 16b, is rotatably supported by a bearing (not shown) incorporated in the bevel gear 21 with the x1 axis as the rotary shaft center. A bevel gear 41 is projectingly provided at the tip, and meshes with a bevel gear 42 having the y1 axis as a rotation axis. A bearing (not shown) for rotatably supporting the shaft 24 is incorporated inside the bevel gear 42, and a spur gear 44 is projectingly provided at the other end to a bearing (not shown) provided on the bending shaft casing 60. And rotatably support it.

The spur gear 26 meshes with a spur gear 27 fitted on a shaft 28 having the y0 axis, which is the center axis of the wrist bending, as its axis. The shaft 28 penetrates the shaft 46 and has a reduction ratio of 1/1.
1, a bearing (not shown) in the shaft 46 fitted to the input portion of the second reducer 32 for a bend shaft, a bearing (not shown) provided in the bend shaft reducer housing 62, and a bend. A bearing (not shown) in the shaft reduction gear output shaft 34 rotatably supports the shaft 28. The output shaft 34 is rotatably supported by a bearing (not shown) provided in the bending shaft casing 60, and is connected to the rotating shaft casing 61.

The spur gear 44 meshes with a spur gear 45 fitted on a shaft 46, and the shaft 46 is a bending shaft casing 60.
A bearing (not shown) provided on the rotary shaft casing 61 and a bearing (not shown) provided on the rotary shaft casing 61 are rotatably supported, and a bevel gear 49 is fitted at an intermediate position. Bevel gear 49
A bearing (not shown) provided on the rotary shaft casing 61 is rotatably supported and meshes with a bevel gear 51 having the x0 axis, which is the center axis of rotation of the wrist, as its axis.

The bevel gear 51 is fitted to the input portion of the second reduction gear 54 for the rotary shaft having a reduction ratio of 1/12, and the bearing (not shown) provided in the reduction gear housing 63 for the rotary shaft and the rotary shaft. A bearing (not shown) in the connection seat 55 with the casing 61 rotatably supports it. A bearing (not shown) provided outside the connection seat 55 rotatably supports the reduction shaft output shaft 64 for the rotation shaft. The backlash of the bevel gear in the wrist mechanism 1 and the wrist drive mechanism 4 adjusts the thickness of the shim, and the backlash of the spur gear adjusts the pitch in a two-divided configuration in the tooth thickness direction.

In the embodiment, the first and second speed reducers for each shaft have the same reduction ratio, but the reduction ratio is set to 1/5 to 1/25 depending on the size of the load inertia of the power transmission component. This combination also satisfies the effect of the present invention.

In the wrist mechanism of the robot having the above structure, the rotation of the torsion shaft driving motor 12a is transmitted by deceleration by the first speed reducer 13a, and the second speed is transmitted through the spur gear (not shown). It is transmitted to the speed reducer 15 and, after deceleration, the torsion shaft 16a.
Rotates, and the arm 2 can rotate about the x1 axis.
The second speed reducer 15 reduces a rotation error such as backlash between the spur gears (not shown) by a reduction ratio.

On the bending shaft, the rotation of the driving motor 12b is transmitted by deceleration by the first speed reducer 13b, and the bending shaft 16b is rotated via a spur gear (not shown). Bending axis 16
The rotation of b is performed by the bevel gears 21 and 22 by the bending shaft 16b.
And a spur gear 2 that is meshed with the spur gear 26.
7 rotates and transmits to the input part of the second reduction gear 32 for a bending shaft by the shaft 28 having the bending center axis y0 axis as its axis.

The rotation of the shaft 28 is transmitted to the output shaft 34 of the speed reducer for the bending shaft after being decelerated by a predetermined ratio, and the rotary shaft casing 61 bolted to the output shaft 34 rotates about the y0 axis.
Between spur gears (not shown), between bevel gears 21 and 22,
Then, the rotation error caused by the backlash between the spur gears 26 and 27, the clearance of the bearing portion, etc.
The second reducer 32 for the bending shaft is reduced by the reduction ratio.

Regarding the rotary shaft, the rotation of the drive motor 12c is transmitted by deceleration by the first speed reducer 13c.
6c rotates. The rotation of the rotating shaft 16c is controlled by the bevel gear 4
1 and 42 rotate around the y1 axis orthogonal to the rotating shaft 16c, and the spur gear 44 protruding from the other end of the bevel gear 42 and the spur gear 45 meshing with the spur gear 44 rotate, and the y0 axis is the center of rotation. Bevel gear 49 rotates.

The rotation of the bevel gear 49 is transmitted to the input part of the second speed reducer 54 for the rotating shaft by the bevel gear 51 meshing with the bevel gear 49, with the center axis of rotation of the wrist being the x0 axis as the center of rotation, and is reduced at a predetermined ratio. After that, the speed reducer housing 63 for the rotary shaft, which is bolted to the second speed reducer 54 for the rotary shaft.
Rotates around the x0 axis. The rotation error generated by the backlash between the bevel gears 41 and 42, between the spur gears 44 and 45, and between the bevel gears 49 and 51, and the clearance of the bearing portion is caused by the second reduction gear 54 for the rotating shaft by the reduction ratio. It shrinks.

As described above, according to the present invention, since the speed reducer is provided in the wrist driving actuator section and the wrist mechanism section,
As the power transmission component, it is possible to use a member that maintains rigidity such that vibration such as chatter does not occur. On the other hand, 2
Since it is a step reduction system, it is possible to reduce the diameter and weight of the power transmission shaft, and to reduce the size and weight of each component such as gears and bearings in the wrist mechanism. The load inertia of the wrist drive mechanism is small, and the response of commands from the actuator is improved. Furthermore, the rotation error due to the backlash of the spur gear or the bevel gear, the clearance of the bearing, etc. is reduced by the reduction ratio of the speed reducer. Therefore, it is possible to prevent deterioration of the positioning accuracy of the wrist tip portion, and it is possible to perform a highly accurate and smooth robot operation. Because of these, the operating points of the torsion axis, bending axis, and rotation axis intersect at one point,
The calculation formula is simplified, the calculation processing is fast, and the movement trajectory and positioning performance are stable.

[Brief description of drawings]

FIG. 1 is an overall view of the present invention

FIG. 2 is a view on arrow AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a sectional view taken along line CC of FIG.

[Explanation of symbols]

 104 Upper arm part 10a Actuator 12a 1st reducer 16a Torsion shaft 10b Actuator 12b 1st reducer 16b Bending shaft 10c Actuator 12c 1st reducer 16c Rotating shaft 15 2nd reducer 32 32nd 2 speed reducer 54 2nd speed reducer 70 Operating point

Claims (4)

[Claims] 1. A robot having a three-degree-of-freedom wrist including an upper arm portion, an upper arm driving portion, a lower arm driving portion, and a turning portion, wherein an upper arm portion 104 includes a wrist driving portion 4 and a wrist portion 1, and a wrist driving portion 4 Is provided with a torsion shaft 16a on the actuator 12a via the first speed reducer 13a, a bending shaft 16b on the actuator 12b via the first speed reducer 13b, and a first speed reducer on the actuator 12c. Rotary shaft 1 via machine 13c
6c, the shafts 16a, 16b, 16c are provided concentrically, the torsion shaft 16a is connected to the wrist portion 1 through the second reduction gear 15, and the bending shaft 16b and the rotary shaft 16c are connected to the wrist portion 1.
A robot with a wrist with 3 degrees of freedom, characterized by being connected to. 2. The robot having a three-degree-of-freedom wrist according to claim 1, wherein the bending shaft 16b and the wrist portion 1 are connected to each other via a second speed reducer 32 of the wrist portion 1. 3. The robot having a wrist with three degrees of freedom according to claim 1, wherein the rotary shaft 16c and the wrist portion 1 are connected to each other via a second speed reducer 54 of the wrist portion 1. 4. The working point 70 is formed by making the axis of the second speed reducer 32 and the axis of the second speed reducer 54 orthogonal to the axis of the torsion shaft 16a. A robot having a wrist with 3 degrees of freedom described in 1.