JPH06102312B2 - Power transmission mechanism of robot joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement in a power transmission mechanism of a joint portion such as an arm of an industrial robot.

[Prior Art] When driving a part having a joint, such as an arm of an industrial robot, if one drive system is operated depending on the content of the power transmission mechanism, other drive systems are also operated with the interlocking motion. It is known that a so-called induced motion may occur, which is disclosed in Japanese Patent Publication No. 58-35836.

[Problems to be Solved by the Invention] However, under the condition that two sets of joints are arranged side by side so as to correspond to an elbow and a wrist of an industrial robot arm or the like, a swinging motion is performed at each joint. There was no other power transmission mechanism that could prevent the induced motion when it was exposed, except to directly drive each joint. The content disclosed in the above publication is a means for preventing induced motion in the rotational motion of the wrist part, and is completely different from the case of the rocking motion of the joint parts in which the two sets are arranged side by side and cannot be applied.

And this induced motion has a great influence on the work mainly based on the CP (Continuous Path Control) method that regulates the entire trajectory of the movement path, such as painting work and welding work. For example, in teaching, it is necessary to correct the motion error due to the induced motion every time the original motion is stopped at a moving distance on the motion path, and the teaching motion is complicated and requires a lot of time. Further, when the induced amount is taken into consideration, the actual operating angle needs to be larger than the apparent operating angle. Therefore, the actuator has to be upsized, and the resolution is also reduced.

The present invention was devised in view of the problems of the conventional robot arm described above, and an object thereof is to provide a power transmission mechanism for a robot joint that does not cause induced motion.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the present invention provides three first, second and third teeth having the same number of teeth on the first joint portion 3 on one end side of the first arm 1. Is provided with a first gear train 19 in which mutually mutually engaged shafts of the bevel gears (13, 15, 17) are orthogonal to each other, and the rotation shaft of the third bevel gear 17 on the first arm side of the first gear train 19 is provided. A hollow first intermediate shaft 35 is provided at the center of the second joint 5 on the other end side of the first arm.
The first bevel gear 13 outside the first arm 1 facing the third bevel gear 17 and extending near the
A hollow first input shaft 11 is fixedly provided to the rotation axis of the first gear train 19 of the first joint part 3, and the third, fourth, fifth, and sixth teeth having the same number of teeth are provided inside the first gear train 19. A second gear train 31 in which the axes of the bevel gears (25, 27, 29) are meshed with each other at right angles to each other,
A sixth bevel gear 29 on the side of the first arm of the second gear train 31.
A second intermediate shaft 43, which is concentric with the first intermediate shaft 35, is fixed to the axis of the second intermediate shaft 43 and extends to the vicinity of the second joint, and a seventh bevel gear 45 for driving the second arm is fixed to the extended end thereof. The second input shaft 23 is fixed to the shaft center of the fourth bevel gear 25 outside the first arm of the second gear train 31, and the first input shaft 11 and the first intermediate shaft 35 are provided. A shaft 21 of a second bevel gear 15 that meshes with the first and third bevel gears (13, 17) provided in the first arm 1 is fixedly provided to the first arm 1, and the second input shaft 23 and the second intermediate shaft 43 are provided. The shaft 33 of the shaft of the fifth bevel gear 27 that meshes with the fourth and sixth bevel gears (25, 29) provided on the first arm 1 is rotatably supported. The differential gear mechanism 49 is provided on the second joint portion 5 of the
And the second joint 5 of the first arm 1
Rotatably provided for the differential gear mechanism 49.
The other output shaft 63 is rotatably provided with respect to the second joint 5, and a tenth bevel gear 39 for giving rotation to the differential gear mechanism 49 is fixedly provided on the output shaft 63, and the first output shaft 63 is also provided.
A ninth bevel gear 37 having the same number of teeth, which meshes orthogonally to the axis of the tenth bevel gear 39, is fixedly provided at the end of the intermediate shaft 35 near the second joint, and further, an outer shell 59 of the differential gear mechanism 49 is provided. And an eighth bevel gear which meshes in a direction orthogonal to the axis of the second arm driving seventh bevel gear 45 and has a gear ratio twice that of the seventh bevel gear 45.
47 was fixedly provided to form a power transmission mechanism of the robot joint.

[Operation] Since the power transmission mechanism of the robot joint of the present invention is configured as described above, the differential gear mechanism effectively operates,
By setting the tooth ratio of the transmission gear to a predetermined ratio and combining with this, the inconvenient induced motion caused by the motion transmitted via each joint is canceled.

[Embodiment] An embodiment of the power transmission mechanism of the robot joint according to the present invention will be described below with reference to the drawing of FIG.

Joints are provided on both ends of the first arm 1 having a cylindrical cross section, one side shown on the left side of the drawing is the first joint section 3, and the other side shown on the right side of the drawing is the second joint section 5. ing. Another arm 7 is connected to the outer side of the first joint section 3, and a second arm 9 is connected to the outer side of the second joint section 5.

A hollow shaft-shaped first input shaft 11 for driving the first joint part 3 is arranged at the center of the other arm 7 along the length direction of the arm 7. At the tip of the first input shaft 11, there is provided a first gear train 19 in which first, second and third bevel gears 13, 15 and 17 are arranged and meshed in a U shape. The first input shaft 11 is fitted and fixed to the first bevel gear 13 of the bevel gears. Of the bevel gears of the first gear train 19, the shaft 21 of the second bevel gear 15 that engages with the first bevel gear 13 is formed so as to project in the direction perpendicular to the first input shaft 11, and the end portion of the arm 7 is rotated. The first arm 1 on the outside of the arm 1
It is fixed to the end of. Therefore, when the first input shaft 11 is rotated, the shaft 21 rotates via the first and second bevel gears 13 and 15, and this rotation causes the first arm 1 to swing about the shaft 21.

A second input shaft 23 for driving the other joint part of the first arm 1, that is, the second joint part 5, is rotatably fitted in the hollow shaft of the first input shaft 11 in a concentric state. 2nd input shaft
At the tip of 23, there are three bevel gears 4th, 5th and 6th.
A second gear train 31 in which 5,27,29 are arranged and meshed in a U shape is provided, and a fourth bevel gear of these gears is provided.
The tip of the second input shaft 23 is fitted and fixed to 25.

The shaft 33 of the fifth bevel gear 27, which is intermediate between the bevel gears of the second gear train 31, has a shape projecting in a direction perpendicular to the second input shaft 23, and the ends of the arm 7 and the first arm 1 are rotatable. Penetrates into a pivotal state. First gear train 19 and second gear train 31
The first joint portion 3 has a configuration in which the first joint portion 3 is disposed in a substantially overlapping manner as shown in the figure. The shafts 21 and 33 of the second and fifth bevel gears 15 and 27 in the middle of the gear trains 19 and 31 are arranged on the same shaft center, and these shafts 21 and 33 serve as the first joint portion. It is the center of rotation, that is, the center of swing of the first arm 1.

From the third bevel gear 17 of the first gear train 19, a first intermediate shaft 35 having a hollow cross section is arranged along the central axis of the first arm 1 to near the second joint 5. At the tip of the first intermediate shaft 35, there is provided a third gear train 41 in which two ninth and tenth bevel gears 37 and 39 are arranged and meshed in an L shape. Second gear train
The sixth bevel gear 29 out of 31 and the second intermediate shaft 43 are rotatably fitted in the hollow portion of the first intermediate shaft 35 along the central axis of the first arm 1 and arranged up to the vicinity of the second joint 5. And a seventh bevel gear 45 for driving the second arm at the tip,
An eighth bevel gear 47 for inputting rotation to the differential gear mechanism is arranged and meshed in an L-shape to connect the second intermediate shaft 43 and the next differential gear mechanism 49.

The differential gear mechanism 49 is provided in a configuration in which four bevel gears 51, 53, 55 and 57 of the eleventh, twelfth, thirteenth and fourteenth are arranged and meshed in a square shape. An outer shell body 59 rotatably supporting each shaft of these gears surrounds each gear, and the eighth bevel gear 47 is mounted on the outer circumference of the outer shell body 59. Of the axes of the four bevel gears of the differential gear mechanism 49, the two output shafts 61 and 63 having their axes in the direction orthogonal to the first and second intermediate shafts 35 and 43 are of course on the same axis. Although they are arranged, they respectively extend so as to project to the outside of the differential gear mechanism. One of the output shafts 61 penetrates and fixes the end of the second arm 9, and further rotatably penetrates the end of the first arm 1. The other output shaft 63 is fitted and fixed to the first bevel gear 39 of the third gear train 41, and further rotatably passes through the respective end portions of the first arm 1 and the second arm 9.

The combination of the differential gear mechanism 49, the third gear train 41, and the seventh and eighth bevel gears 45, 47 is arranged in the second joint portion 5 as shown in FIG. . The second arm 9 swings with respect to the first arm 1 by driving the second input shaft 23 about the two output shafts 61 and 63. In this way, the hand 65 corresponding to the finger is attached to the tip of the second arm 9 corresponding to the wrist.

The bevel gears included in the first, second, and third gear trains 19, 31, 41, and the differential gear mechanism 49 described above have the same number of teeth in each combination, that is, a 1: 1 gear ratio. Has been done. Then, only the combination of the seventh bevel gear 45 and the eighth bevel gear 47 at the end portion of the first intermediate shaft 35 on the second joint portion 5 side is configured with the gear ratio of 1: 2.

Note that the above-mentioned configuration has been described with respect to the first joint portion 3 and the second joint portion 5 related to the first arm 1 and the second arm 9, and the rotary motion mechanism and the hand of another arm 7 not shown. The rotary motion mechanism 65, the grip motion mechanism, and the like are not included in the scope of the present invention, and a description thereof will be omitted.

The operation of the power transmission mechanism of the robot joint of the present invention configured as described above will be described.

Now, the second input shaft 23 is not moved and the first joint part 3 is driven. That is, when the first input shaft 11 that swings the first arm 1 is rotated by 90 degrees, for example, the first and second gears of the first gear train 19 are rotated.
The first arm 1 is 90 by the shaft 21 via the bevel gears 13 and 15.
Swing once. However, at the same time, the sixth bevel gear 29 of the second gear train 31 is also rotated by 90 degrees with the swing of the first arm 1, so that the sixth bevel gear 27 is meshed with the fifth bevel gear 27 and is rotated corresponding to the rotation of 90 degrees. Forced (induced movement).

Then, through the seventh and eighth bevel gears 45 and 47, the differential gear mechanism 4
Rotate the outer shell 59 of 9 by 45 degrees to move the 12th and 14th bevel gears 53, 5
7 makes a rotation of 45 degrees and generates a movement for rotating the thirteenth bevel gear 55 by 90 degrees, that is, an induced movement for swinging the second arm 9 by 90 degrees.

However, the third bevel gear 17 of the first gear train 19 rotates 90 degrees, the first intermediate shaft 35 rotates, and the ninth and tenth gears of the third gear train 41
Differential gear mechanism 4 via output shaft 63 via bevel gears 37, 39
The eleventh bevel gear 51 in 9 is rotated 90 degrees. This action cancels the induced motion that causes the second arm 9 to swing 90 degrees, that is, the motion that causes the thirteenth bevel gear 55 to rotate 90 degrees. Therefore, no induced motion occurs.

Next, when the second input shaft 23 that drives the second joint portion 5, that is, swings the second arm 9 is rotated, for example, 90 degrees without moving the first input shaft 11, when the second gear train 31 The second intermediate shaft 43 rotates 90 degrees via the fourth, fifth and sixth bevel gears 25, 27 and 29. Subsequently, the outer shell 59 of the differential gear mechanism 49 rotates 45 degrees via the seventh and eighth bevel gears 45 and 47, and the twelfth and fourteenth bevel gears 53 and 57 rotate 45 degrees. At this time, the first input shaft 11 is stopped and the shaft 63 of the tenth bevel gear 39 connected to the first input shaft 11 is stopped.
Is also stationary. Of course, the eleventh bevel gear 51 does not move, so the twelfth, fourteenth bevel gear 53,
The rotation of 57 by 45 degrees causes the 13th bevel gear 55 to rotate by 90 degrees, and the second
The arm 9 is rotated 90 degrees.

As described above, the swing motion corresponding to the rotation angle of each input shaft can be performed without generating the induced motion in the first joint part 3 and the second joint part 5.

The power transmission mechanism of the robot joint portion according to the present invention is not limited to the one embodiment described above, and various modifications and applications are possible. For example, a spiral gear may be used instead of the bevel gear of each gear train to more smoothly transmit the rotation. Alternatively, the first arm and the first and second intermediate shafts are rotationally engaged with each other by a spline mechanism or the like so that the first arm and the second intermediate shaft can be expanded and contracted in the axial direction. A structure with variable length can be easily realized.

[Effects of the Invention] As is clear from the above description, according to the configuration of the present invention, the power transmission mechanism of the robot joint having the structure that does not reliably generate the induced motion can be obtained in a compact and cohesive state.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a power transmission device for a robot joint according to the present invention. Description of main drawings 1 ... 1st arm, 3 ... 1st joint part 5 ... 2nd joint part, 9 ... 2nd arm 11 ... 1st input shaft, 19 ... 1st gear train 23 ... … Second input shaft, 31 …… Second gear train 35 …… First intermediate shaft, 41 …… Third gear train 43 …… Second intermediate shaft, 49 …… Differential gear mechanism

Claims (1)

[Claims] 1. A power transmission mechanism for a joint part of an articulated robot comprising a plurality of joints and arms, wherein the first joint part 3 on one end side of the first arm 1 has first and second teeth having the same number of teeth. The third 3
A first gear train 19 in which the axes of the individual bevel gears (13, 15, 17) are meshed with each other at right angles to each other is provided, and the rotation of the third bevel gear 17 of the first gear train 19 on the side of the first arm is provided. A hollow first intermediate shaft 35 is provided so as to extend to the vicinity of the second joint 5 on the other end side of the first arm, and the third bevel gear is provided.
A hollow first input shaft 11 is fixedly provided on the rotation shaft center of the outer first bevel gear 13 of the first arm 1 opposed to the first arm 1 and inside the first gear train 19 of the first joint portion 3. The second gear train 31 in which the axes of the three bevel gears (25, 27, 29) having the same number of teeth, that is, the fourth, the fifth, and the sixth, are meshed at right angles to each other, is provided.
A sixth bevel gear 29 on the side of the first arm of the second gear train 31.
The second intermediate shaft 43, which is concentric with the first intermediate shaft 35, is fixed to the axis of the second intermediate shaft 43 and extends to the vicinity of the second joint, and the seventh bevel gear 45 for driving the second arm is fixed to the extended end thereof. The second input shaft 23 is fixed to the shaft center of the fourth bevel gear 25 outside the first arm of the second gear train 31, and the first input shaft 11 and the first intermediate shaft 35 are provided. A shaft 21 of a second bevel gear 15 that meshes with the first and third bevel gears (13, 17) provided in and is fixedly provided to the first arm 1, and the second input shaft 23 and the second intermediate shaft 43 are provided. A shaft 33 of a fifth bevel gear 27 that meshes with the fourth and sixth bevel gears (25, 29) provided on the first arm 1 is rotatably supported on the shaft 33. A differential gear mechanism 49 is provided on the two-joint portion 5, a second arm 9 is fixedly provided on one output shaft 61 of the differential gear mechanism 49, and the first arm 1 is provided. The second joint 5 is rotatably provided, and the other output shaft 63 of the differential gear mechanism 49 is rotatably provided with respect to the second joint 5 and the output shaft 63 is provided with the differential. A tenth bevel gear 39 that provides rotation to the gear mechanism 49 is fixedly provided, and the first intermediate shaft is also provided.
A ninth bevel gear 37 having the same number of teeth, which meshes at right angles with the axis of the tenth bevel gear 39, is fixedly provided at an end portion of the second joint 35 near the second joint 35, and the outer shell body 59 of the differential gear mechanism 49 is further provided with the above-mentioned. Second
A power transmission mechanism for a robot joint, comprising an eighth bevel gear 47 fixedly provided, which meshes at right angles with the axis of the arm driving seventh bevel gear 45 and has a gear ratio of twice that of the seventh bevel gear 45.