JP2017052032A - Stopper mechanism of robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stopper mechanism of a robot which inhibits occurrence of collision noise and enables accurate positioning in a structure using a movable stopper.SOLUTION: A stopper mechanism 10 of an embodiment includes a movable stopper 11 and a fixed stopper 12 which contacts with the movable stopper 11 from a circumferential direction. The movable stopper 11 comprises: a body part 20 formed by a non-elastic material and having a contact surface (a circumferential direction side end surface of a protruding part 20a) contacting with the fixed stopper 12; and an elastic member 21 which is formed by an elastic material and is provided at the body part 20 while protruding further than the contact surface in the circumferential direction and exposing the contact surface.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a robot stopper mechanism that defines a rotation range of an arm.

  In the robot, a plurality of arms are connected by a joint structure, and each arm is configured to rotate relatively around the joint. At this time, a movable range is set in advance for each arm, and each arm normally rotates only within the movable range by controlling the rotation of the motor. However, in general robots, a mechanical stopper mechanism is provided in order to prevent the arm from rotating beyond the movable range due to unintended factors (see, for example, Patent Document 1).

JP 2014-190566 A

  The mechanical stopper mechanism has a structure that restricts further rotation of the arm by physically contacting the stoppers provided on each arm. However, when each stopper is fixed to the arm, the rotation angle of the arm is less than ± 180 °. For this reason, some of the stoppers are movable to enable rotation exceeding ± 180 °. Hereinafter, the movable stopper is referred to as a movable stopper, and the stopper in contact with the movable stopper is referred to as a fixed stopper.

  Such a movable stopper is provided, for example, so as to be movable in a groove formed in the circumferential direction. When the fixed stopper comes into contact with the movable stopper, the movable stopper is moved by the fixed stopper. And when it is pushed to the end of the groove part, it cannot move any more, and therefore, further rotation of the arm is restricted.

Since the position at which the arm does not rotate any more is a reference position for positioning the rotation axis of the arm, it is necessary to set the position accurately.
By the way, since the movable stopper moves by contacting with the fixed stopper as described above, a collision sound is generated when contacting the fixed stopper. Therefore, the movable stopper is covered with an elastic member such as an elastomer, for example, so that a collision sound is not generated when it comes into contact with the fixed stopper.

However, in the case where the movable stopper is covered with the elastic member, the dimension of the movable stopper in the circumferential direction changes due to the elastic member bending when positioning. And the change of the dimension becomes an error, and there exists a possibility that it cannot position correctly. In addition, since the amount of bending of the elastic member changes depending on the force pressing the arm, the amount of bending is not constant, and the positioning accuracy may not be stable.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a robot stopper mechanism capable of accurately positioning while suppressing the occurrence of collision noise in a configuration using a movable stopper. is there.

  According to the first aspect of the present invention, the stopper mechanism defines a rotation range of the second arm that rotates relative to the first arm, and is provided on the first arm. A movable stopper that is movable in the circumferential direction that is coaxial with the rotation axis when the arm is rotated, and is provided on the second arm, and is fixed to the second arm and the second arm rotates. And a fixed stopper 12 that contacts the movable stopper from the circumferential direction.

  The movable stopper is formed of a non-elastic material and has a main body having a contact surface with the fixed stopper, and is formed of an elastic material so that the fixed stopper comes into contact with the contact surface when the fixed stopper is pressed against the movable stopper. And an elastic member that covers the movable stopper.

  Here, the time when the fixed stopper is pressed against the movable stopper means the time when positioning is performed, and the fixed stopper is strongly pressed against the movable stopper side by applying a torque sufficient to allow the elastic member to bend sufficiently. Shows the state. That is, the elastic member protrudes in the circumferential direction from the contact surface when a relatively small force is applied, such as when the elastic member is not simply in contact. On the other hand, the contact surface of the elastic member is exposed when a force sufficient to bend the protruding length at the time of positioning is applied.

  In this case, since the main body is covered with the elastic member, the contact between the main body and the fixed stopper is prevented by the elastic member when the movable stopper and the fixed stopper simply contact each other. Thereby, generation | occurrence | production of the collision sound which arises when the main-body part which is an inelastic member, and a fixed stopper can be avoided.

  On the other hand, when positioning the rotary shaft, the fixed stopper is strongly pressed against the movable stopper, so that the elastic member is bent by the pressing force, the contact surface is exposed from the elastic member, and the fixed stopper is the contact surface of the main body. To touch. In other words, as long as a pressing force sufficient to expose the contact surface is applied, the circumferential dimension of the movable stopper at the time of positioning coincides with the width of the main body formed of the inelastic material. Thereby, at the time of positioning, the position of the fixed stopper is always the same position, and the determination accuracy is stabilized.

Therefore, in the configuration using the movable stopper, the positioning can be accurately performed while suppressing the occurrence of the collision sound.
In the invention described in claim 2, the movable stopper protrudes from the main body portion in the circumferential direction, and an end portion on the protruding side has a convex portion serving as a contact surface. The elastic member covers the movable stopper so as to protrude in the circumferential direction from the convex portion, and has an opening that exposes the convex portion at a position corresponding to the convex portion.

  When the main body is covered with the elastic member, if the contact surface of the main body is formed as a uniform plane, for example, the elastic member may be deformed and enter the contact surface when the fixed stopper is pressed during positioning. is there. And when an elastic member penetrate | invades into a contact surface, since the dimension of the circumferential direction of a movable stopper changes according to pressing force, there exists a possibility that an error may arise.

Therefore, when the elastic member is elastically deformed (when contracted in the circumferential direction) by providing a convex portion protruding in the circumferential direction from the main body portion and using the end surface of the convex portion as a contact surface, the elastic member The deformation due to the bending is absorbed by the difference in position between the main body portion and the convex portion in the circumferential direction.
Accordingly, the elastic member is prevented from entering the contact surface, that is, the end surface on the circumferential side of the convex portion, and an error in the circumferential dimension of the movable stopper is prevented. Therefore, the possibility that the positioning accuracy is deteriorated can be reduced.

  In the invention described in claim 3, the movable stopper moves in a groove portion having a predetermined length in the circumferential direction formed in the first arm, and the convex portion is a portion in contact with the fixed stopper. , And a portion that contacts the groove. And the opening part which exposes the convex part of the site | part which contacts a groove part is also formed in the elastic member.

  When the movable stopper moves in the groove portion, if a convex portion is provided only on the contact surface with the fixed stopper, the above-described error may occur depending on how the elastic member is bent at the portion in contact with the groove portion. Further, when the movable stopper comes into contact with the groove portion, there is a possibility that a collision noise is generated.

  Therefore, by forming a convex portion at a portion that contacts the groove portion and forming an opening that exposes the convex portion in the elastic member, the collision sound is generated on both the side that contacts the fixed stopper and the side that contacts the groove portion. And the occurrence of errors in the circumferential dimension of the movable stopper. Thereby, a possibility that positioning accuracy may deteriorate can be reduced.

In the invention described in claim 4, the opening of the elastic member is formed so as to become wider as the distance from the convex portion increases. Thereby, when an elastic member elastically deforms, the escape part for releasing an elastic member is formed, and a possibility that an elastic member may penetrate | invade into a contact surface can be reduced.
In the invention described in claim 5, the opening is formed with a gap between the opening and the projection. Thereby, when an elastic member elastically deforms, the escape part for releasing an elastic member is formed, and a possibility that an elastic member may penetrate | invade into a contact surface can be reduced.

The figure which shows the robot by one Embodiment typically The figure which shows an example of the attachment position of a stopper mechanism typically The figure which shows the principal part of the stopper mechanism typically The figure which shows the structural example of the movable stopper typically Diagram showing an example of the contact state between the movable stopper and the fixed stopper in time series FIG. 1 schematically showing another configuration example of the movable stopper FIG. 2 schematically showing another configuration example of the movable stopper

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the robot 1 of this embodiment has a known configuration as a so-called six-axis vertical articulated robot, and a shoulder 3 is mounted on a base 2 via a first axis (J1). It is connected to be rotatable in the horizontal direction. The shoulder 3 is coupled to the lower end of the lower arm 4 extending upward via the second shaft (J2) so as to be rotatable in the vertical direction. A first upper arm 5 is connected to the tip of the lower arm 4 via a third shaft (J3) so as to be rotatable in the vertical direction. A second upper arm 6 is coupled to the distal end portion of the first upper arm 5 via a fourth shaft (J4) so as to be able to rotate. A wrist 7 is connected to the distal end portion of the second upper arm 6 via a fifth shaft (J5) so as to be rotatable in the vertical direction. A flange 8 is connected to the wrist 7 via a sixth shaft (J6) so as to be twisted and rotatable.

  The base 2, the shoulder 3, the lower arm 4, the first upper arm 5, the second upper arm 6, the wrist 7 and the flange 8 function as the arm of the robot 1, and the illustration of the flange 8 which is the tip of the arm is omitted. However, a hand (also called an end effector) is attached. For example, the hand holds and transfers a workpiece (not shown), or is attached with a tool for processing the workpiece. Each axis (J1 to J6) provided in the robot 1 is provided with a motor (not shown) as a drive source corresponding to each axis.

  In addition, the 1st arm and the 2nd arm which were described in the claim mean having two arms which rotate relatively. Therefore, for example, when the base 2 is the first arm, the shoulder 3 that rotates relative to the base 2 corresponds to the second arm. Further, when the shoulder 3 is viewed as the first arm, the lower arm 4 or the base 2 that rotates relative to the shoulder 3 corresponds to the second arm. Hereinafter, in the present embodiment, an example in which the base 2 is a first arm and the shoulder 3 is a second arm will be described.

  As shown in FIGS. 2 and 3, a stopper mechanism 10 in the present embodiment is provided at a connecting portion between the base 2 and the shoulder 3. The stopper mechanism 10 includes a movable stopper 11 provided on the base side and a fixed stopper 12 (see FIG. 3) provided on the shoulder side. The movable stopper 11 is provided so as to be movable in the groove 13 provided on the base 2 side. On the other hand, the fixed stopper 12 is fixedly provided on the shoulder 3, and moves together with the shoulder 3 when the shoulder 3 rotates.

  More specifically, as shown in FIGS. 4A and 4B, the movable stopper 11 formed in a substantially L shape includes a main body 20 and an elastic member 21 that covers the surface of the main body 20. Has been. 4A shows a state in which the movable stopper 11 is viewed from the inside in the radial direction, and the horizontal direction in the figure corresponds to the circumferential direction. FIG. 4B shows the movable stopper 11 viewed from the radial direction.

  The main body portion 20 is formed with a plurality of convex portions 20a protruding in the circumferential direction. In addition, although mentioned later for details, the two convex parts 20a provided in the upper side of the figure are portions that come into contact with the fixed stopper 12, and the end surfaces on the circumferential side thereof correspond to the contact surface with the fixed stopper 12. . Further, the two convex portions 20 a provided on the lower side in the drawing are portions that come into contact with the inner surface side of the groove portion 13, and the end surfaces on the circumferential side thereof correspond to the contact surface with the groove portion 13. Moreover, the main-body part 20 is not flat form in this embodiment, but is formed in the shape curved along the circumferential direction. For this reason, when contacting the fixed stopper 12, as will be described later, the contact is made in a plane.

  The main body 20 is formed of a metal material that is an inelastic material, including the convex portion 20a. Note that the non-elastic material means a highly rigid material that does not require substantially considering elastic deformation. For this reason, not only a metal material but a non-metal material may be used as long as there is almost no elastic deformation. In the present embodiment, the main body portion 20 is formed of a metal material including the convex portion 20a. Therefore, it can be considered that the circumferential width D of the main body portion 20 including the convex portion 20a does not elastically deform and is a substantially constant value. Further, since the fixed stopper 12 is also formed of a metal material, deformation when contacting the movable stopper 11 can be almost ignored.

  On the other hand, the elastic member 21 is formed of an elastic material such as an elastomer. In addition, the material of the elastic member 21 is not limited to an elastomer. The elastic member 21 has a rectangular opening 21 a at a position corresponding to the convex portion 20 a of the main body 20. The opening 21a is formed to be approximately the same size as the convex portion 20a. That is, the elastic member 21 covers the main body portion 20 in a state where the contact surface with the fixed stopper 12 (end surface of the convex portion 20a) is exposed and protruded by a distance d in the circumferential direction from the convex portion 20a. ing. That is, the elastic member 21 covers the movable stopper 12 so that the fixed stopper 12 contacts the contact surface of the movable stopper 11.

  For this reason, as shown in FIG. 4B, when the movable stopper 11 is viewed from the radial direction, the surface of the convex portion 20a (the end surface in the circumferential direction, which corresponds to the contact surface) can be visually recognized. The distance d may be appropriately set according to the physical properties of the elastic member 21 and the pressing force (which can be calculated from the motor torque) that presses the fixed stopper 12 against the movable stopper 11 as will be described later.

  The movable stopper 11 is provided in a groove 13 formed on the base 2 side so as to be movable in the groove 13. More specifically, on the base 2 side, a holder main body 14 provided with the groove 13 and a lid member 15 that covers the groove 13 in a state where a part of the groove 13 is opened are provided. And the movable stopper 11 is arrange | positioned in the groove part 13 so that free movement is possible in the state which block | closes the level | step-difference part 11a from upper direction with the cover member 15. FIG.

Next, the operation of the above configuration will be described.
As shown in FIG. 5A, the fixed stopper 12 approaches the movable stopper 11 located on the center side of the groove portion 13 (a position not in contact with the end of the groove portion 13) from the circumferential direction as indicated by an arrow X. Assume that the fixed stopper 12 comes into contact with the movable stopper 11 as shown in FIG. In this state, the fixed stopper 12 substantially contacts the elastic member 21. In this case, the elastic member 21 does not bend so much when the movable stopper 11 and the fixed stopper 12 are in contact with each other. Therefore, the main body 20 of the movable stopper 11 and the fixed stopper 12 do not come into contact with each other. Is suppressed.

  On the other hand, as shown in FIG. 5C, when the fixed stopper 12 is strongly pressed against the movable stopper 11 by the motor torque at the time of positioning the rotary shaft, the pressing force that presses the fixed stopper 12 against the movable stopper 11 As a result, the amount of bending of the elastic member 21 increases.

  When the amount of bending of the elastic member 21 (in this embodiment, the amount of compression or deformation of the elastic member 21) exceeds the above-mentioned distance d (see FIG. 3), the movable stopper 11 protrudes toward the fixed stopper 12 side. While the portion 20 a directly contacts the fixed stopper 12, the opposite convex portion 20 a directly contacts the end of the groove portion 13 in the circumferential direction. At this time, the deformation due to the bending of the elastic member 21 is absorbed by the difference in the circumferential position between the main body portion 20 and the convex portion 20a because the elastic member 21 contracts in the circumferential direction.

At this time, as described above, since the main body portion 20 and the convex portion 20a are highly rigid, in the state where the elastic member 21 is bent by the distance d, the distance from the end of the groove portion 13 to the fixed stopper 12 is the convex portion 20a. This corresponds to the width D of the main body portion 20 including. That is, the position of the fixed stopper 12 can be accurately positioned at the position of the width D from the end of the groove 13. The same applies to the case where the fixed stopper 12 contacts from the opposite side to the case of FIG.
As described above, the stopper mechanism 10 can accurately define the position when positioning the rotary shaft while suppressing the generation of the collision sound at the time of simple contact.

According to the embodiment described above, the following effects can be obtained.
The stopper mechanism 10 defines a rotation range of a second arm (shoulder 3 in the embodiment) that rotates relative to the first arm (base 2 in the embodiment). A movable stopper 11 that is movable in a circumferential direction that is coaxial with a rotation axis when the second arm rotates, and is provided on the second arm, fixed to the second arm and And a fixed stopper 12 that contacts the movable stopper 11 from the circumferential direction when the second arm rotates.

The movable stopper 11 is made of an inelastic material, and has a main body portion 20 having a contact surface with the fixed stopper 12 (in this embodiment, an end surface on the circumferential side of the convex portion 20a) and an elastic material. And an elastic member 21 covering the movable stopper 12 so that the stopper 12 contacts the contact surface of the movable stopper 11.
Thereby, when the movable stopper 11 and the fixed stopper 12 are simply in contact with each other, the elastic member 21 prevents the main body portion 20 and the fixed stopper 12 from contacting each other, and the occurrence of a collision sound can be avoided.

  On the other hand, when positioning the rotary shaft, the fixed stopper 12 is strongly pressed against the movable stopper 11, so that the elastic member 21 is bent by the pressing force so that the fixed stopper 12 contacts the contact surface of the main body 20. Become. At this time, the main body portion 20 is formed of a non-elastic material and thus does not elastically deform. As a result, the fixed stopper 12 does not rotate any further.

  With this configuration, even if the movable stopper 11 is provided with the elastic member 21, the circumferential dimension of the movable stopper 11 at the time of positioning can be determined by applying a pressing force sufficient to expose the contact surface. The width of the portion 20 (in this embodiment, the circumferential width D including the main body portion 20 and the convex portion 20a) is a constant value. Therefore, the position of the fixed stopper 12 at the time of positioning is always the same position, and the determination accuracy is stabilized.

Therefore, in the configuration using the movable stopper 11, the positioning can be accurately performed while suppressing the generation of the collision sound.
The movable stopper 11 protrudes from the main body 20 in the circumferential direction, and has a protruding portion 20a whose end on the protruding side becomes a contact surface. And the elastic member 21 has the opening part 21a which exposes the said convex part 20a in the position corresponding to the convex part 20a, while covering the movable stopper 11 in the state which protrudes in the circumferential direction rather than the convex part 20a. ing.

  In the case of the configuration in which the main body portion 20 is covered with the elastic member 21 as in the present embodiment, if the contact surface of the main body portion 20 is formed as a uniform plane, for example, when the fixed stopper 12 is pressed during positioning, The member 21 may be deformed and enter the contact surface. When the elastic member 21 enters the contact surface, an error occurs in the circumferential dimension of the movable stopper 11, which causes a deterioration in positioning accuracy.

Therefore, when the elastic member 21 is elastically deformed (when contracted in the circumferential direction) by providing the convex portion 20a projecting in the circumferential direction from the main body portion 20 and using the end surface of the convex portion 20a as a contact surface. The deformation due to the bending of the elastic member 21 is absorbed by the difference in position between the main body portion 20 and the convex portion 20a in the circumferential direction.
Thereby, the elastic member 21 is prevented from entering the contact surface, that is, the end surface on the circumferential side of the convex portion 20a, and an error in the circumferential dimension of the movable stopper 11 is prevented. Therefore, it is possible to prevent the possibility of deteriorating positioning accuracy.

The movable stopper 11 moves in the groove portion 13 having a predetermined length in the circumferential direction formed in the first arm, and the convex portion 20a is in contact with the fixed stopper 12, and It is formed in a portion that contacts the groove 13. And the elastic member 21 has the opening part 21a which exposes the convex part 20a of the site | part which contacts the groove part 13. As shown in FIG.
When the movable stopper 11 moves in the groove portion 13, if the convex portion 20 a is provided only on the contact surface with the fixed stopper 12, an error as described above may occur depending on the bending state of the elastic member 21 at the portion in contact with the groove portion 13. May occur.

  Therefore, the convex part 20a is formed also in the site | part which contacts the groove part 13, and the opening part 21a which exposes the convex part 20a is formed in the elastic member 21, and the side which contacts the fixed stopper 12, and the groove part 13 are contacted. On both sides, no dimensional error can occur. Therefore, it is possible to prevent the possibility of deteriorating positioning accuracy.

  In the case of this embodiment, the stopper mechanism 10 is provided at the joint between the base 2 and the shoulder 3. When the shoulder 3 rotates, the amount of movement of the hand of the robot 1 increases. That is, if the rotation axis (J1) of the shoulder 3 is not correctly positioned, a large error occurs in the hand of the robot 1. Accordingly, by providing the stopper mechanism 10 of the present embodiment at the joint between the base 2 and the shoulder 3, the rotation axis (J1) of the shoulder 3 can be accurately positioned, and the operation accuracy of the robot 1 is improved. Can be prevented from deteriorating.

  In the case of this embodiment, the main body 20 is formed of a metal material. When the elastic member 21 is formed of an elastomer, generally, a mold manufacturing method in which a resin material is provided on the main body portion 20 at a high temperature is often employed. Therefore, the productivity of the movable stopper 11 can be improved by forming the main body portion 20 from a metal material that can withstand the high temperature during molding.

The present invention is not limited to the embodiment described above and illustrated in the drawings, and various modifications and extensions can be made without departing from the scope of the invention.
In the embodiment, the quadrangular columnar convex portion 20a is illustrated, but other shapes such as a columnar shape and a triangular prism shape may be used. In this case, if the contact surface is formed to be a flat surface, the size and shape of the tip side and the base (end on the main body 20 side) may be different.

In the embodiment, the example in which the stopper mechanism 10 is provided in the joint portion between the base 2 and the shoulder 3 has been described. However, the stopper mechanism 10 may be provided in another joint portion.
In the embodiment, a 6-axis vertical articulated robot is illustrated, but the present invention has arms that rotate relative to each other even in other configurations such as a 4-axis horizontal articulated robot or a so-called 7-axis robot. Any robot can be applied.

In the embodiment, an example is shown in which the opening 21a having substantially the same size as the contact surface of the convex portion 20a is formed in the elastic member 21, but the opening 21a of the elastic member 21 is formed as shown in FIG. 6A, for example. Alternatively, the width may be increased as the distance from the convex portion 20a increases. Thereby, when the elastic member 21 elastically deforms, a possibility that the elastic member 21 may enter the contact surface can be reduced.
In this case, it is preferable that the position in contact with the convex portion 20a is closer to the main body portion 20 than the contact surface (the end surface on the circumferential direction side of the convex portion 20a). Thereby, when the elastic member 21 is elastically deformed, the possibility that the elastic member 21 enters the contact surface can be further reduced.

Further, as shown in FIG. 6B, the opening 21a may be formed with a gap between the opening 21a and the protrusion 20a. In this case, the inner surface of the opening portion 21a and the side surface of the convex portion 20a (the surface in the vertical direction of the convex portion 20a in the drawing) function as a relief portion, and the possibility that the elastic member 21 enters the contact surface can be reduced.
Further, as shown in FIG. 6C, the opening 21a may be formed so as to become wider as the distance from the convex portion 20a increases and with a gap between the convex portion 20a. . Even with such a configuration, the risk of the elastic member 21 entering the contact surface can be reduced.

  Further, as shown in FIG. 7A, the opening 21a may be circular. In this case, the shape of the opening 21a may be an ellipse or a triangle according to the shape of the convex portion 20a. Further, as shown in FIG. 7B, one opening 21a may be formed corresponding to the plurality of convex portions 20a.

  In the drawings, 1 is a robot, 2 is a base (arm), 3 is a shoulder (arm), 4 is a lower arm (arm), 5 is a first upper arm (arm), 6 is a second upper arm (arm), 7 Is a wrist (arm), 8 is a flange (arm), 10 is a stopper mechanism (robot stopper mechanism), 11 is a movable stopper, 12 is a fixed stopper, 13 is a groove, 20 is a body (contact surface), and 20a is convex. Portions (contact surfaces), 21, 30, and 40 are elastic members, and 21a is an opening.

Claims (5)

A stopper mechanism for a robot that defines a rotation range of a second arm that rotates relative to the first arm,
A movable stopper provided on the first arm and movable in a circumferential direction coaxial with a rotation axis when the second arm rotates;
A fixed stopper provided on the second arm, fixed to the second arm and contacting the movable stopper from the circumferential direction when the second arm rotates,
The movable stopper is
A body portion formed of an inelastic material and having a contact surface with the fixed stopper;
A robot stopper mechanism comprising: an elastic member formed of an elastic material and covering the movable stopper so that the fixed stopper contacts the contact surface when the fixed stopper is pressed against the movable stopper. The movable stopper protrudes from the main body portion in the circumferential direction, and has a protruding portion whose end on the protruding side becomes the contact surface,
The elastic member covers the movable stopper in a state of projecting in the circumferential direction from the convex portion, and an opening for exposing the convex portion is formed at a position corresponding to the convex portion. The robot stopper mechanism according to claim 1. The movable stopper moves in a groove portion having a predetermined length in the circumferential direction formed on the first arm,
The convex part is formed at a part that contacts the fixed stopper and a part that contacts the groove part,
The robot stopper mechanism according to claim 2, wherein the elastic member is formed with an opening that exposes the convex portion at a portion in contact with the groove.   4. The robot stopper mechanism according to claim 2, wherein the opening portion of the elastic member is formed so as to become wider as the distance from the convex portion increases.   The robot stopper mechanism according to claim 2, wherein the opening of the elastic member is formed with a gap between the opening and the convex.

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