JPS6125788A - Balancer for robot arm - 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 an industrial robot in which members disposed above and below are connected so as to be relatively movable back and forth by an arm that can swing back and forth. This invention relates to a balance device that is used to bias the arm in an upright direction against the collapse moment caused by gravity and to balance the arm against gravity.

(Prior Art and its Problems) As a conventional balance device for a robot arm, when the arm is constituted by two parallel links, a cylinder unit has been used that pushes apart the space between the two links. In such a balance device, a suitably regulated fluid pressure must be supplied to the cylinder unit, and the balance device as a whole has the drawback of being very expensive. Moreover, if the fluid pressure supply system malfunctioned, the balance force would be lost, and there was a risk that the robot arm would collapse unexpectedly due to gravity.

In order to solve these problems, a rubber spring, which is generally used in the same way as a torsional respring, is installed between a square shaft and a square tube loosely fitted to the square shaft. It is also conceivable to use a biasing means interposed with an elastic body such as rubber that is elastically coupled so as to be relatively rotatable, but the first problem with this type of biasing means is that the Since the allowable relative rotation range between the square shaft and the square tube is relatively small, it cannot be applied as a balance device for a robot arm that has a swing range larger than the permissible rotation range. The second problem is that even if a plurality of biasing means are used in combination as a balance device for a robot arm, the force of the arm will be different when the arm is tilted forward and when it is tilted backward. The problem is that it is not possible to change the magnitude of the biasing force (balance force) that acts in the standing direction.

(Means for solving the problem) The first invention was made to solve the first problem mentioned above, and its feature is that the members arranged above and below can be moved back and forth. In the robot 7), which is connected by an arm so as to be relatively movable back and forth, a square shaft and a square tube loosely fitted on the square shaft are provided between at least one of the upper and lower arm pivot members and the arm. A biasing means having an elastic body interposed between the arm and the arm, which holds the arm relatively rotatably against elasticity in either the left or right direction, is interposed in such a manner that the arm is biased in the standing direction from the forward and backward tilted posture; There is a gap between one of the square tube or the square shaft of this biasing means and the arm or the arm pivot member connected thereto, when the arm swings within a certain range in the upright position. The point is that a play space is formed in which the power means can be freely rotated.

Further, the second invention has been made to solve the second problem as well as the first problem, and is characterized by an arm that can swing the members arranged vertically back and forth. In the robot, the distal end movable member is connected via an arm that can move vertically relative to the upper member, and at least one of the upper and lower arm pivot members and the arm. A first biasing means is interposed between the square shaft and the square tube loosely fitted to the square shaft, and an elastic body is interposed between the square shaft and the square tube loosely fitted to the square shaft to allow relative rotation between the square shaft and the square tube. , the arm is biased in the upright direction from the forward and backward tilted position, and one of the square cylinder or the square shaft in this biasing means is connected to the arm or the arm pivot member connected thereto. A play space is formed therebetween, in which the biasing means is allowed to rotate freely when the arm swings within a certain range in an upright position;
Further, a second biasing means similar to the biasing means is interposed between at least one of the upper and lower arm pivot members and the arm, and the second biasing means has a rectangular tube or a square shaft. When the arm swings and tilts toward the side where the distal end movable member is located against the urging force of the first urging means, the arm is connected to the arm or the arm pivot member connected thereto. The other feature is that a play space is formed in which the second biasing means rotates freely.

(Function) In the balance device according to the first invention, when the arm in the upright position swings within the certain range, that is, when the arm swings in a region where the lodging moment acting on the arm is very small. , the biasing means only freely rotates together with the arm and does not function as a means for applying a balancing force to the arm, and the arm swings back and forth beyond the certain range, that is, the dead zone for the biasing means. Only when the arm swings, the square axis of the biasing means and the square tube rotate relative to each other against the elasticity of the elastic body, and the restoring force of the elastic body that has been elastically deformed is applied to gravity. It will act on the arm as an opposing balancing force.

Further, in the balance device according to the second invention, the following action is performed in addition to the action of the first invention.

That is, due to the presence of the vertically swinging arm and the movable end member, the lodging moment acting on the front and back swinging arm is larger when the arm swings forward than when it swings backward. However, when the longitudinal swinging arm swings backward beyond the dead zone for the first biasing means, the second biasing means simply rotates freely together with the first biasing means, and only the first biasing means A balance force is applied to the arm to counter the lodging moment, and when the longitudinal swinging arm swings forward beyond a dead zone relative to the first biasing means, the second and first biasing means function. The balance force of both biasing means acts on the arm in the upright direction.

(Example) An example of the present invention will be described below based on the attached illustrative drawings.

In FIG. 1, reference numeral 1 denotes a rotary table rotatable around a vertical axis, which is rotatably supported on a base 2 and can be rotated in any direction forward or reverse by a rotation drive means within the base 2. . Reference numeral 3 denotes an intermediate movable member, which is supported by the rotary table 1 via a longitudinal swing arm 4 so as to be movable longitudinally and in parallel. The longitudinal swinging arm 4 is connected to a drive link 5 parallel to each other, forming a parallel four-speed link together with the rotary table 1 and the intermediate movable member 3.
and a posture maintaining link 6. Reference numeral 7 denotes a distal end movable member, which is supported by the intermediate movable member 3 via a vertically swinging arm 8 so as to be vertically movable in parallel. The vertically swinging arm 8 is composed of a drive link 9 and a posture holding link 10 that are parallel to each other and constitute a parallel four-speed link together with the intermediate movable member 3 and the distal end movable member 7. Reference numeral 11 denotes a pneumatic motor that swings the back-and-forth swinging arm 4 in the front-rear direction with respect to the rotary table 1 via the drive link 5, and is attached to the rotary table 1.

Reference numeral 12 denotes a pneumatic motor that swings the vertically swinging arm 8 in the vertical direction relative to the intermediate movable member 3 via the drive link 9, and is attached to the intermediate movable member 3. A robot hand equipped with an appropriate drive actuator (not shown) is attached to the tip movable member 7. Arm 4 against
By appropriately combining the back and forth rocking of the arm 8 and the vertical rocking of the arm 8 relative to the intermediate movable member 3, the tip movable member 7 can be moved to an arbitrary position while keeping its posture constant relative to the base 2. I can do it.

Next, the balance device of the present invention in the above-mentioned robot will be explained based on FIGS. 2 to 6. There is a One urging means 13 is interposed, and a second urging means 14 is interposed between the drive link 5 and the intermediate movable member 3.

Both the first and second biasing means 13.14 include a square shaft 15 with a square cross section and a square tube 16 with a square cross section loosely fitted therein.
, and a plurality of elastic bodies 17 such as rubber in the circumferential direction interposed between the two. Reference numeral 18 denotes a square tubular collar that is fitted onto the square shaft 15 at a location in contact with the elastic body 17 . The elastic body 17 is a bar-shaped member having a substantially triangular cross section, and separates the spaces having a triangular cross section between the four corners of the square tube 16 and the four sides of the square shaft 15 (collar 18) opposed thereto. It is decorated to fill.

The first biasing means 13 has shaft portions 15 protruding from both ends of its square shaft 15.
a is rotatably supported on the rotary table 1 via a bearing 19,
The posture maintaining link 6 is attached to both ends of the square shaft portion 15b of the square shaft 15 via a bracket 20,
The link 6 is supported so as to be able to swing together with the square shaft 15 about the axis of the square shaft 1S. Further, the rectangular tube 16 is connected to the rotary table 1 via a pair of left and right connecting plates 21. The pair of left and right connecting plates 21 are fixed and erected on a member 22 installed in the rotary table 1, and in the square tube support JL23 through which the square tube 16 passes,
It is provided with a play space 23a that allows the rectangular tube 16 to freely rotate within a range of 15 degrees.

Similarly to the first urging means 13, the second urging means 14 also has its square shaft 15 fixed to the drive link 5, and its square tube 16 connected to the intermediate movable member 3 via the connecting plate 24. Therefore, the drive link 5 swings relative to the intermediate movable member 3 together with the square shaft 15 of the second biasing means 14 about the axis of the square shaft 15 . Further, the connecting plate 24 is fixed to a member 25 which is installed in the intermediate movable member 3, and the connecting plate 24 is fixed to the member 25 within a 45 degree range in the square tube support hole 26 through which the square tube 16 passes. It is provided with a play space 26a that allows the rectangular tube 16 to freely rotate.

The rectangular cylinder support hole 23 and play space 23a of the connecting plate 21 in the first biasing means 13 are formed so as to perform the following functions.

That is, the posture holding link 6 changes from a vertically standing posture as shown in FIG. When the square tube 16 of the first biasing means 13 swings within the link 6, the square tube 16 of the first biasing means 13 is prevented from rotating rearward together with the link 6 by the square tube support hole 23 of the connecting plate 21, and only the square shaft 15 becomes the link. 6
The elastic body 17 is elastically deformed between the square shaft 15 and the square tube 16 as shown in FIG. 2, and the restoring force is applied to the link 6 as a balancing force in the standing direction. act.

When the posture holding link 6 swings forward (in the direction of arrow 29) from a vertically standing posture, the first biasing means 13 is activated within the dead zone 30 having an angle of 15'' as shown in FIG.
Since the square tube 16 freely rotates forward together with the square shaft 15 and the elastic body 17 together with the link 6 within the play space 23a in the square tube support hole 23 of the connecting plate 21, the elastic body 17 is not deformed. , the first biasing means 13 does not apply a balancing force to the link 6 in the upright direction. When the posture maintaining link 6 swings forward (in the direction of arrow 29) within the forward swing range 31 of 30 degrees beyond the dead zone 30, the first biasing means 13 is activated as shown in FIG. The square tube 16 is prevented from rotating forward together with the link 6 by the square tube support hole 23 of the connecting plate 21, and only the square shaft 15 rotates forward together with the link 6. The elastic body 17 is elastically deformed between it and the cylinder 16, and its restoring force acts on the link 6 as a balancing force in the upright direction.

The rectangular tube support hole 26 and play space 26a of the connecting plate 24 in the second biasing means 14 are formed so as to perform the following functions.

That is, the drive link 5 changes from a vertically standing position as shown in FIG. 4 to a position backward (
When swinging within the swing range 28 of the angle 306 (in the direction of arrow 27) (when swinging forward with respect to the intermediate movable member 3), the angle l#16 of the second biasing means 14 is connected to the connecting plate. Since the square shaft 15 and the elastic body 17 integrally rotate together with the link 5 in the play space 26a in the square tube support hole 26 of No. 24, the elastic body 17 is not elastically deformed and the second biasing means 14 is No balancing force is applied to the drive link 5 in the standing direction.

From the vertical position of the drive link 5 to the front (arrow 29
As shown in FIG. 5, within the range of the dead zone 30 of 15°, when the movable member 3 is pivoted backwards (in the direction of the intermediate movable member 3), Similarly, the square tube 16 is connected to the square shaft 15 and the elastic body 1 in the play space 26a.
7 and the link 5, the elastic body 17 is not deformed, and the second biasing means 14 does not apply a balancing force to the link 5 in the upright direction. When the drive link 5 exceeds the dead zone 30 and swings forward (in the direction of arrow 29) within the forward swing range 31 at an angle of 30'',
As shown in FIG. 6, the square tube 16 of the second biasing means 14 is prevented from rotating forward together with the link 5 by the square tube support hole 26 of the connecting plate 24, and only the square shaft 15 is connected to the link 5.
Since the elastic body 17 rotates together with the square shaft 15 and the square tube 16, the elastic body 17 is elastically deformed, and the restoring force acts on the link 5 as a balancing force in the upright direction.

As is clear from the above action, the longitudinal swinging arm 4 swings back and forth within a range of 30" backward (in the direction of arrow 27) and 45" forward (in the direction of arrow 29) from the vertical standing position. When the arm 4 is within a swinging range 28.31 of 30'' in both the front and back that exceeds the 15-degree angle of the fuwaza band 30, the first biasing means 13 applies the force to the arm 4 at that angle. Provides a corresponding amount of balancing force in the standing direction. In other words, the back and forth swing 7-me 4 moves 30 degrees backward and 4 degrees forward.
5 degrees, a total range of 75'', whereas the square shaft 15 and square tube 16 of the first biasing means 13 swing in a range of 306 degrees front and back, a total of 60 inches, centering on the neutral position. There will be relative rotation within.

Further, the second biasing means 14 is configured such that the front and rear swinging arm 4 is in the dead zone 3.
Only when the arm 4 is within the forward swing range 31 of 30 degrees exceeding 0, a balancing force in the upright direction corresponding to the angle is applied to the arm 4. That is, while the longitudinal swinging arm 4 swings back and forth within a range of 75° as described above, the square shaft 15 and the square tube 16 of the second biasing means 14 swing forward about the neutral position. Relative rotation will occur only within a range of 30°.

Therefore, the balance force acting on the front-rear swing arm 4 in the upright direction is such that the arm 4 is in an area where the falling moment due to gravity is very small, that is, in the dead zone 30 with respect to the first and second re-energizing means +314. Sometimes zero,
A backward swing range 2 in which the arm 4 exceeds the dead zone 30
8, the force is applied only by the first biasing means 13, and when the arm 4 is within the forward swinging range 31 exceeding the dead zone 30, the force is applied by both the first biasing means 13 and the second biasing means 14. Given.

Note that any number of first biasing means 13 and second biasing means 14 can be used. In particular, when the longitudinal swinging arm 4 is composed of two links 5 and 6 as in the embodiment, there are a total of four link joints, so the biasing means is applied to each link joint. Can be distributed. Furthermore, it is also possible to arrange a plurality of biasing means in parallel in the direction of the pivot axis in one link pivot portion.

Further, in the embodiment, the square shaft 15 of the biasing means is connected to the link side, and the square tube 16 is connected to the link pivot member side, but this can also be reversed. Furthermore, although the play spaces 23a and 26a for obtaining the fuwawa belt 30 are formed in the support portion of the square tube 16, it is also possible to form the play spaces in the support portion of the square shaft 15.

Further, it is also possible to provide play space in both the square shaft support part and the square tube support part.

(Effect of the invention) According to the present invention (first invention) that can be implemented as described above,
Since a dead zone for the biasing means is provided within the range of forward and backward swing of the robot arm, the relative rotation tolerance range of the biasing means (i.e., the tolerance between the rectangular shaft and the rectangular cylinder connected by an elastic body) (relative rotation range), it is possible to increase the range of back-and-forth swing of the robot arm. In other words, it has become possible to utilize the biasing means, which has a smaller allowable relative rotation range than the longitudinal swing range of the robot arm, as a means for applying a balancing force to the robot arm. Moreover, the fuwazai with respect to the biasing means is
Since the lodging moment acting on the robot arm is set in a very small region, there is no possibility that the existence of the dead zone will have a substantially negative effect on the robot arm drive system or safety.

Further, according to the balance device of the second invention, although the above-mentioned biasing means whose biasing force cannot be freely adjusted during operation is used as the balancing force applying means, it is difficult to swing backward. The balance force applied to the forward-swinging arm can be made larger as necessary than the balance force applied to the forward-swinging arm. Therefore, due to the existence of the vertically swinging arm and the movable end member supported by it, the lodging moment is larger when the longitudinally swinging arm is swinging forward than when it is swinging backward. A suitable balance can be added.

[Brief explanation of the drawing]

Figure 1 is a side view of the entire robot, Figure 2 is an enlarged side view with a partial cutout of the main parts, Figure 3 is an enlarged vertical front view of the main parts, and Figures 4 to 6 are when the arm swings. FIG. 6 is a longitudinal sectional side view of a main part showing the operating state of the biasing means. DESCRIPTION OF SYMBOLS 1... Rotating table, 3... Intermediate movable member, 4... Front-rear swing arm, 5.9... Drive link, 6.10...
Posture holding link, 7... Tip movable member, 8... Vertical swing arm, 11.12... Pneumatic motor, 13.
...First biasing means, 14...Second biasing means, 15...
・Square shaft, 16... Square tube, 17... Elastic body, 21.2
4... Connecting plate, 23.26... Square tube support hole, 23a
, 26a...play space, 30...dead zone.

Claims (2)

[Claims] (1) In a robot in which members disposed vertically are connected so as to be relatively movable back and forth by an arm that can swing back and forth, an angular shaft is connected between at least one of the upper and lower arm pivot members and the arm. and a rectangular tube loosely fitted to the rectangular shaft, and a biasing means interposed between the elastic body and the rectangular tube that connects both of them so that they can rotate relative to each other against elasticity in either the left or right direction. The biasing means is interposed between one of the rectangular tube or the rectangular shaft and the arm or the arm pivot member connected thereto, so as to bias the arm in the upright direction. A balance device for a robot arm, which forms a play space in which the biasing means freely rotates when swinging within a certain range in a posture. (2) In a robot in which members disposed above and below are connected so as to be relatively movable back and forth by an arm that can swing back and forth, and a movable tip member is further connected to the upper member via an arm that can swing up and down. between at least one of the upper and lower arm pivot members and the arm, and a square shaft and a square tube loosely fitted to the square shaft, the two are rotated relative to each other against elasticity. A first biasing means interposed with an elastic body that can be coupled to the arm is interposed so as to bias the arm in the upright direction from the forward and backward tilted posture, and one of the square tube or the square shaft in this biasing means is provided. and the arm or the arm pivoting member connected thereto, a play space is formed in which the biasing means is allowed to freely rotate when the arm swings within a certain range in the upright position; A second biasing means similar to the biasing means is interposed between at least one of the upper and lower arm pivot members and the arm, and one of the square tube or the square shaft in the second biasing means , between the arm or the arm pivoting member connected thereto, except when the arm swings and tilts toward the side where the distal end movable member is located against the urging force of the first urging means. A robot arm balance device comprising a play space in which the second biasing means rotates freely.