JPH10118967A - Articulated robot - Google Patents

Abstract

(57) [Summary] In a horizontal articulated robot, a transfer time between two points is reduced, and a driving motor is reduced in capacity. SOLUTION: In an articulated robot provided with a plurality of arms that turn in a horizontal plane, a fixed base 1, a turning head 3 on the fixed base 1, which turns around a vertical axis, and a second head fixed to the turning head 3. 1 arm 5 and auxiliary link 7
A parallelogram link mechanism comprising a first arm 5 and a second arm 12 rotatably mounted on the auxiliary link 7 so as to be coaxial with the connecting axis of the first arm 5 and the auxiliary link 7. A spring device 20 is stretched between the first arm 5 and the second arm 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an industrial robot, and more particularly to a horizontal articulated robot.

[0002]

2. Description of the Related Art In a handling robot, particularly a robot for transferring a work between two processing machines which are relatively far apart, it is required to reduce a moving time between two points in order to reduce a non-machining time. Have been.

As a first example of the prior art, there is a so-called scalar type robot as shown in FIG. FIG. 5 is a plan view showing the configuration of the scalar robot, and FIG.
Is a side view of the same. The configuration of the scalar robot will be described with reference to FIG. 1 is a fixed base,
Fixed at the installation location. A first turning shaft 2 is provided vertically to the fixed base 1, and a turning head 3 is attached so as to be rotatable about the first turning shaft 2. The turning head 3 is driven by a first drive motor 4 mounted in the turning head 3. The turning head 3 includes:
The first arm 5 is fixed. A second pivot 11 is provided vertically at the tip of the first arm 5, and a second arm 12 is attached to be rotatable about the second pivot 11. The second arm 12 is driven by a second drive motor 13 on the first arm 5.

The first prior art has the following problems. First, consider a case where the reference point P at the tip of the second arm 12 moves from the start point A to the end point B along the shortest path, that is, a straight path. In order for the reference point P to move from the start point A to the end point B, the first arm 5 must first turn by the angle α. Second arm 1
2 rotates together with the first arm 5 while maintaining the angle β formed with the first arm 5, so that when the first arm 5 rotates by the angle α, the reference point P moves to the point C. In order for the reference point P to move from the point C to the end point B, it is necessary to turn the second arm 12 by the angle γ. Therefore, in order to move the reference point P from the start point A to the end point B along a straight path, it is necessary to turn the second arm 12 by the angle γ while turning the first arm 5 by the angle α. The operating angle γ of the second arm 12 is
2 with respect to the fixed base 1 and the second
Is different from the angle of the arm 12 with respect to the fixed base 1 by the first
Is larger than the operation angle β because the operation angle β of the arm 4 is added. In other words, the second arm 12
Needs to turn at a higher speed than the first arm 5. In addition, since the first arm 5 and the second arm 12 rotate simultaneously, an interference torque is generated between the first drive motor 4 and the second drive motor 13. That is, the interference torque increases the load on the first drive motor 4 and reduces the load on the second drive motor 13. In summary, the first conventional technique has the following problems. (1) Since the operating angle of the second arm 12 is large, it is necessary to increase the turning speed of the second arm 12 in order to perform a linear operation between two points. The capacity increases. (2) Since the interference torque due to the turning of the second arm 12 is applied to the first turning shaft 2 as a load, it is necessary to increase the capacity of the first driving motor 4.

As an example of the second prior art, there is a horizontal articulated robot with a parallelogram link mechanism shown in Japanese Utility Model Application Laid-Open No. 6-42089 proposed to solve these problems. FIG. 7 is a plan view of the horizontal articulated robot of Japanese Utility Model Laid-Open No. 6-42089 omitting the structure after the third axis, and FIG. 8 is a side view of the same. The configuration of the horizontal articulated robot with the parallelogram link will be described with reference to FIG.
Reference numeral 1 denotes a fixed base, which is fixed to an installation location. A first turning shaft 2 is provided vertically to the fixed base 1, and a turning head 3 is attached so as to be rotatable about the first turning shaft 2. The swivel head 3 is driven by a first drive motor 4 mounted therein. A first arm 5 is fixed to the turning head 3. A first rotating shaft 6 is provided vertically at the tip of the first arm 5, and an auxiliary link 7 is attached to be rotatable about the first rotating shaft 6. At the other end of the auxiliary link 7, a second rotation shaft 8 is provided vertically, and the link 9 is
Is mounted so as to be rotatable about a rotary shaft 8 of the motor. The other end of the link 9 is rotatably attached to a third rotating shaft 10 provided vertically to the fixed base 1. Thus, the fixed base 1, the first arm 5,
The auxiliary link 7 and the link 9 constitute a parallelogram link mechanism. A second turning shaft 11 is provided on the auxiliary link 7 coaxially with the first turning shaft 5.
The second arm 12 is attached to the auxiliary link 7 so as to be rotatable around the second pivot 11. Second arm 1
2 is driven by a second drive motor 13 on the auxiliary link 7.

[0006]

However, the second prior art also has the following problems. Consider a case where the reference point P at the tip of the second arm 12 is moved from a start point A to an end point B by following a straight line locus. Unlike the case of the first prior art, when the first arm 5 turns, the second arm 12 moves while maintaining the angle with respect to the fixed base 1 by the action of the parallelogram link mechanism. The operating angle can be small. But,
Since no interference torque is generated between the first drive motor 4 and the second drive motor 13, the second drive motor 13
Since the driving torque of the motor increases, it is necessary to increase the capacity. The first driving motor 4 is connected to the second arm 12.
Since the vehicle turns with the subsequent components as loads, a large driving torque is required. Accordingly, an object of the present invention is to provide a horizontal articulated robot in which the operating angle of the second arm 12 is small and the driving torque of the first driving motor 4 and the second driving motor 13 is small. I do.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a horizontal articulated robot having a parallelogram link and a spring device suspended between a first arm and a second arm. Thus, acceleration and deceleration of the first turning axis and the second turning axis are assisted.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of an articulated robot according to an embodiment of the present invention, in which structures after a third axis are omitted, and FIG. 2 is a side view of the same. In the figure, reference numeral 1 denotes a fixed base, which is fixed to an installation place. A swivel head 3 is rotatably attached to the fixed base 1 around a first swivel shaft 2 provided vertically. Swivel head 3
Is driven by a first driving motor 4 mounted in the turning head 3. The swivel head 3 has a first
Arm 5 is fixed and extends horizontally. That is,
The first arm 5 turns around the first turning axis 2 in a horizontal plane. At the tip of the first arm 5, a first rotation shaft 6 is provided vertically, and the auxiliary link 7 is connected to the first rotation shaft 6.
It is attached so that it can rotate around. Auxiliary link 7
At one end, a second rotating shaft 8 is provided vertically,
A link 9 is rotatably mounted. One end of the link 9 is rotatably attached to a third rotation shaft 10 provided vertically to the fixed base. Thus, the fixed base 1, the first arm 5, the auxiliary link 7,
The link 9 constitutes a parallelogram link mechanism.
A second turning shaft 11 is provided on the auxiliary link 7 coaxially with the first turning shaft 6. Second arm 12
Is mounted so as to be rotatable around a second pivot shaft 11. The second arm 12 is driven by a second drive motor 13 on the auxiliary link 7 and turns around a second turning axis 11 in a horizontal plane. A spring device 20 has one end pivotally connected to the first arm 5 and the other end pivotally connected to the second arm 12. The configuration of the spring device 20 will be described with reference to FIG. Spring device 20
Consists of a spring box 21, a spring receiver 22, a connecting rod 23, a first coil spring 24, a second coil spring 25, and a brake 24. At the end of the spring box 21, a mounting portion 2
1a is fixed. The other end has a bottom 2
From 1b, a cylindrical support cylinder 21c extends in the length direction of the spring box 21. The spring receiver 22 includes the spring box 21.
In. The connecting rod 23 has an attachment portion 23 at one end.
a is provided. The spring device 20 is mounted on the mounting portion 2.
At 1a, it is pivotally connected to the first arm 5 so as to be freely rotatable, and at the mounting portion 23a, it is pivotally connected to the second arm 12 so as to be freely rotatable. The connecting rod 23 passes through the support cylinder 21c with the end opposite to the mounting part 23a as the head, and
And is connected to the spring receiver 22. The natural length of the first coil spring 24 is
1, and the second coil spring 25 is
It is shorter than the first coil spring 24. First coil spring 24
And the second coil spring 25 are arranged concentrically inside the spring box 21, and have their ends fixed to the spring receiver 22. Since the connecting rod 23 slides on the support cylinder portion 21c, the spring receiver 22, the connecting rod 23, the first coil spring 24, and the second coil spring 25 are integrated,
The inside of the spring box 21 moves freely in the length direction of the spring box 21. The first coil spring 24 and the second coil spring 25 are
Since the connecting rod 23 is shorter than the spring box 21,
When the spring device 20 is in the most contracted state, the first coil spring 24 and the second coil spring 25 do not contact the bottom 21b of the spring box. Therefore, the reaction force of the first coil spring 24 and the second coil spring 25 is not applied to the connecting rod 23. In this state, the connecting rod 23 is pulled out of the spring box 21, that is,
The spring device 20 extends and continues until the first coil spring 24 contacts the bottom 21b of the spring box. First coil spring 2
When 4 contacts the bottom 21b of the spring box, only the reaction force of the first coil spring 24 acts on the connecting rod. Further connecting rod 23
Is pulled out of the spring box 21, the second coil spring 25
Comes into contact with the bottom 21b of the spring box, and the first coil spring 2
4 and the reaction force of the second coil spring 25 is applied to the connecting rod 23. The above is described again with reference to FIG. FIG.
FIG. 4 is a diagram illustrating a relationship between displacement and force of the spring device 20.
The displacement becomes greater as the length of the spring device 20 in the most contracted state is set to 0 and the connecting rod 24 is pulled out of the spring box 21 and the length of the spring device 20 is increased. Displacement is 0 to D1
Until then, the force is zero. When the displacement becomes larger than D1, a force is generated according to the displacement-reaction curve 31 of the first coil spring 24. When the displacement reaches D2, a force is generated according to the displacement-reaction curve of the second coil spring 25. Therefore, the displacement-reaction curve 33 of the spring device 20 is a non-linear curve obtained by combining the displacement-reaction curve 31 of the first coil spring 24 and the displacement-reaction curve of the second coil spring 25.
By selecting a combination of the length and the spring constant of the two coil springs, the displacement-reaction characteristic of the spring device 20 can be selected in a desired form. The brake 26 is connected to the bottom 21 a of the spring box 21.
And restricts the sliding of the connecting rod 23 with respect to the spring box 21 in response to an external command. Now, consider a case where the reference point P at the tip of the second arm 12 is moved from point A to point B. When the reference point P is at the point A, since the spring device 20 is stretched, tension is generated in a direction in which the second arm 12 and the first arm 5 are drawn toward each other. Therefore, the tension of the spring device 20 generates a torque that causes the second arm 12 to pivot clockwise around the second pivot axis 11. Further, since the second arm 12 is attached to the auxiliary link 7, the tension of the spring device 20 causes the auxiliary link 7 to rotate clockwise around the first rotation shaft 6 with respect to the first arm 5. Also, a torque for rotation is generated. Since the parallelogram link is configured, the clockwise rotation of the auxiliary link 7 causes the first arm 5 to rotate counterclockwise. That is, the tension of the spring device 20 also acts as a torque for turning the first arm 5 counterclockwise around the first turning shaft 2. Thus, when the reference point P moves from the point A to the point B, the spring device 20 acts as a force that assists the acceleration torque. Since the spring device 20 is provided with the displacement-reaction characteristics as described above, a large force is generated when the reference point P is in the acceleration section L1, and a force is generated in the constant speed section L2. do not do.
In the constant speed section, a large torque is not originally required, and when the reference point P passes through the middle point M between the points A and B, the force of the spring device 20 acts in the direction of decelerating the arm.
In order to avoid this, the displacement-reaction characteristics as described above are provided. When the reference point P further enters the deceleration section, the first arm 5 and the second arm 12 move to extend the spring device 20 while resisting the force of the coil spring. In other words, the spring device 20 This time, it works to assist the deceleration of the first arm 5 and the second arm 12. In other words, the spring device 20 serves to convert the kinetic energy of the arm into the distortion energy of the coil spring and store it. Conversely, when the reference point P returns from the point B to the point A, the strain energy stored in the coil spring is converted into kinetic energy of the arm again. When the reference point P is at the point A or the point B and the position is temporarily held for the attachment / detachment of the work, the first driving motor is used to hold the position against the tension of the spring device 20. 4 and 2nd drive motor 13
Requires a large holding torque. At this time, according to a command from a robot control device (not shown), the connecting rod 23 is tightened by the brake 26 to suppress the generation of a large holding torque.
The spring device 20 may be a simple tension spring or a device having a function equivalent thereto, or a solid elastic body such as rubber as long as it has a function similar to a spring. Alternatively, a device utilizing the compressibility of a fluid may be used.
Further, a configuration in which the brake 26 is omitted and the structure is simplified can be considered. In the present embodiment, in order to avoid the complexity of the description, a two-axis articulated robot including the first arm 5 and the second arm 12 rotating in a horizontal plane is used. Even if the robot has three or more axes, the present invention can be implemented if a part of the robot has a horizontal two-axis configuration similar to the present invention.

[0009]

As described above, according to the present invention, the following effects can be obtained. (1) When the horizontal articulated robot is operated to connect two points along a straight path, the operation angle of the second arm can be reduced, so that high-speed operation is facilitated. (2) Since the torque required for starting and stopping the first and second arms is assisted by the spring force, the acceleration / deceleration torque of the drive motor can be reduced. That is, the capacity of the motor can be reduced. (3) At the time of deceleration, the kinetic energy of the arm is converted into the distortion energy of the spring and stored, and at the time of acceleration, the distortion energy of the spring is converted into the kinetic energy of the arm. Therefore, energy loss due to acceleration / deceleration is small, and there is an energy saving effect. . (4) Since the operation of the spring device can be arbitrarily stopped by the brake device, the torque of the drive motor for maintaining the posture of the robot can be reduced, and there is an energy saving effect.

[Brief description of the drawings]

FIG. 1 is a plan view of an articulated robot according to an embodiment of the present invention.

FIG. 2 is a side view of the articulated robot according to the embodiment of the present invention.

FIG. 3 is a side sectional view of a spring device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between displacement and force of a spring device.

FIG. 5 is a plan view of an articulated robot showing an example of the first related art.

FIG. 6 is a side view of an articulated robot showing an example of the first related art.

FIG. 7 is a plan view of an articulated robot showing a second conventional example.

FIG. 8 is a side view of an articulated robot showing an example of a second related art.

[Explanation of symbols]

1: fixed base 2: first turning axis 3: turning head 4: first driving motor 5: first arm 6: first turning axis 7: auxiliary link 8: second turning axis 9 : Link 10: Third rotation axis 11: Second rotation axis 12: Second arm 13: Second drive motor 14: Locus of P point 20: Spring device 21: Spring box 21 a: Mounting part 21 b : Support part 21c: Bottom part 22: Spring support 23: Connecting rod 23a: Mounting part 24: First spring 25: Second spring 26: Brake 31: Curve showing the relationship between displacement and force by the first spring 32: Curve indicating the relationship between displacement and force by the second spring 33: Curve indicating the relationship between displacement and force of the spring device A: Start end of arm movement B: End end of arm movement C: First arm alone Position of reference point P when turned M: Midpoint of A and B points D1: Displacement of the spring device D2: Displacement of the spring device L1: Acceleration section L2: Constant speed section L3: Deceleration section α: Operating angle of the first arm β: Angle between the first arm and the second arm γ: Second Arm movement angle

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Seiji Ogata 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Inside Yaskawa Electric Co., Ltd. (72) Inventor Koichi Yamaguchi 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Yaskawa Electric Corporation

Claims (3)

[Claims] 1. A multi-joint robot having a plurality of arms that turn in a horizontal plane, a fixed base, a turning head that turns on a vertical axis on the fixed base, and a second head that is fixed to the turning head. A parallelogram link mechanism including an arm, an auxiliary link, and a link; and a second arm rotatably mounted on the auxiliary link coaxially with a connection axis between the first arm and the auxiliary link. , The first
An articulated robot having a spring device stretched between the first arm and the second arm. 2. The articulated robot according to claim 1, wherein the spring device has a non-linear characteristic. 3. The articulated robot according to claim 1, wherein the spring device has a brake.