JPH0253589A - Driving device for arm of articulated robot - Google Patents

Abstract

PURPOSE:To make an arm itself slender and to lighten it by crossing two belts inside an arm and winding between both pulleies. CONSTITUTION:Belts 14, 15 are made independent in two pieces, the respective tip is fixed to pulley 11, 12, these belts 14, 15 are wound in reverse direction on the pulley 11, 12, the tip is fixed to the pulley 11, 12 and the intermediate part of these belts 14, 15 is crossed at the top and bottom. As a result, the belts 14, 15 become so-called crossing and shorter than a parallel hanging, so the resonant frequency of the belt 14, 15 does not become low during rotating power transmission, also the arm 2 of an articulated robot 1 can be made slender and lightened at the intermediate part between both pulley 11 and 12, so the movement of the arm 2 of a robot 1 can be quickened at high speed and the positioning accuracy at that time can be increased as well.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an improvement in an arm drive device for an articulated robot.

BACKGROUND OF THE INVENTION Belt transmission devices are often used as arm drive devices for horizontal articulated robots.

A conventional belt transmission device is, for example, disclosed in Japanese Patent Application Laid-Open No. 61-1738.
As seen in Publication No. 75, they are hung in parallel. In parallel belts, the distance between the belts on the tight side and the loose side is equal to the diameter of the pulley, so the arms become thicker and heavier, which causes a decrease in motion performance.

Furthermore, since the distance of the belt that is not wound around the pulleys becomes longer, the resonance frequency becomes lower during transmission of rotational force, especially on the slack side, making it difficult to control the amount of rotation, that is, positioning, with high precision.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to increase the speed of arm rotation and improve positioning accuracy in an arm drive device for an articulated robot.

Solution to the Invention Therefore, the present invention provides a drive pulley on the base side of the arm and a driven pulley on the front side, fixes the front arm to the driven pulley, and connects these pulleys with a belt for transmitting rotational force. In an articulated robot that is wrapped around the The middle part is made to intersect at the top and bottom.

In this way, the belt becomes what is called a cross,
It is shorter than a parallel belt (as a result, the resonant frequency of the belt does not drop during rotational force transmission, and the arm can be tugged at the intermediate part between both pulleys, making it lighter and faster, allowing the robot arm to move faster. Moreover, the positioning accuracy at that time can also be improved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show a horizontal articulated robot 1 of direct-drive type.

The articulated robot 1 includes a first arm 2 as a rear arm,
A second arm 3 is provided as the front arm. These first arm 2 and second arm 3 are driven by a first motor 4 and a second motor 5, respectively, as drive sources. That is, the first motor 4 and the second motor 5 are located at the base of the first arm 2, are fixed in a stacked state in the vertical direction, and serve as the main body of the robot.

The first arm 2 is directly fixed at its base portion to a drive shaft 6 that is integrated with the output shaft of the first motor 4.

Further, the second arm 3 is rotatably supported by upper and lower bearings 8 at the distal end portion of the first arm 2 via a fulcrum shaft 7 fixed to the upper end of the base side. The second arm 3 has a working shaft 13 at its tip that is vertically movable and rotatable.

Further, the output shaft 9 of the second motor 5 passes through the inside of the first motor 4, faces the inside of the first arm 2, and has an intermediate shaft 9a.
At the same time, it is supported by the bearing 10 on the first arm 2 side and is integrated with the drive pulley 11.

The rotational force of the drive pulley 11 is driven by two independent belts 14 and 15. That is, these belts 14.15 are shifted in the axial direction and are wound in opposite directions around the drive pulley 11 and the driven boob 1712 fixed to the fulcrum shaft 7, and are crossed at the intermediate portion. 15 are fixed to the outer circumferential surfaces of the drive boob IJII and the driven pulley 12 by fixtures 16 and 17, respectively. Note that the fixtures 16 and 17 are fixed at positions that allow the necessary rotation angle for each drive pulley 11 or driven pulley 12. In this way, the two belts 14 and 15 form a so-called cross,
Since they intersect at the middle, the first arm 2 is thinner and lighter at the middle, except for the joints at both ends.

Effect of the Invention When the articulated robot l moves, the first arm 2 and the second arm
The arm 3 moves the working shaft 13 at the tip to a predetermined position by rotating by a required angle in the horizontal direction.

That is, the rotation of the first motor 4 is directly transmitted to the first arm 2 via the drive shaft 6. In addition, the second motor 5
The rotation of is transmitted to the drive pulley 11 via the output shaft 9. As a result, the rotation of the drive boob I711 is transmitted to the driven pulley 12 and the shaft 7 via the cross belt 14.15, and is finally transmitted to the second arm 3 within a maximum rotation angle range of 220 @. It is transmitted by. Of course, the first of these
The rotation amounts of the motor 4 and the second motor 5 are controlled by known pulse servo control.

In the process of transmitting this rotational force, the free section of the belt 14.15, that is, the section that is not wound around the drive pulley 11 or the driven pulley 12, is shorter than in the case of parallel winding. Since the hanging part becomes longer, the rigidity of the belt 14, 15 becomes higher, and the resonant frequency becomes higher compared to the conventional parallel belt, so the servo gain of the second motor 5 becomes accurate and positioning is improved. The accuracy, that is, the accuracy of the stop position will be improved.

In addition, since the rotational force is transmitted in the opposite direction between the drive boob IJ 11 and the driven pulley 12, the level of interference between the rotational force of the first arm 2 and the rotational force of the second arm 3 is low. As a result, vibrations during exercise, especially during acceleration and deceleration, are suppressed to a low level.

Furthermore, the middle part of the first arm 2 is thinner to correspond to the cross-crossing of the belts 14 and 15, and the weight of the first arm 2 itself can be set to be smaller than that of conventional ones, so it is easy to rotate. Since the required rotational force is small and the inertia when stopped is also small, the articulated robot 1 can move at high speed.

Other Embodiments Although the second motor 5 is located below the first motor 4 in the above embodiment, the second motor 5 may also be located above the first arm 2. 1 may be installed inside the base side of the arm 2.

Aoi Akira's Effects In the present invention, the two belts are wound in a cross pattern within the arm between both pulleys, so the arm itself can be made thinner and lighter, and the free section of the belt can be hung in parallel. Because it is shorter than the belt, the resonant frequency of the belt can be set higher. This makes it possible to speed up the motion of the articulated robot and improve positioning accuracy.

Furthermore, because the belt crosses the rotation direction of the drive pulley and the driven pulley in opposite directions, the degree to which the drive torque of the second motor interferes with the rotational movement of the first arm can be suppressed. .

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of an arm drive device of an articulated robot, and FIG. 2 is a plan view of essential parts of the arm drive device. 1...Multi-joint robot, 2...1st arm, 3...2nd arm
Arm, 4...first motor, 5...second motor, 9...
Output shaft, 11... Drive pulley, 12... Driven pulley, 1
4.15...Belt, 16.17...Fixing tool.

Claims (2)

[Claims] (1) A drive pulley located at the base of the rear arm and rotated by a drive source such as a motor, a driven pulley located at the front end of the rear arm and fixed to the fulcrum side of the front arm, and a pulley that extends between both pulleys. In an articulated robot consisting of a belt,
A multi-joint system characterized by having two independent belts, each wound around a pulley in an axially shifted manner in opposite directions, both ends of each belt being fixed to the pulley, and both belts intersecting in the middle. Robot arm drive device. (2) An arm drive device for an articulated robot, characterized in that the belt intersection portion of the rear arm is made thinner.