JP6672649B2 - Robot stopper mechanism - Google Patents

Description

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

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

JP 2014-190566 A

  The mechanical stopper mechanism has a structure in which stoppers provided on each arm are in physical contact with each other, thereby restricting further rotation of the arm. However, when each stopper is fixed to the arm, the rotation angle of the arm becomes less than ± 180 °. For this reason, there is a type in which one of the stoppers is movable to enable rotation exceeding ± 180 °. Hereinafter, the movable stopper is referred to as a movable stopper, and the stopper on the side in contact with the movable stopper is referred to as a fixed stopper.

  Such a movable stopper is provided, for example, movably in a groove formed in the circumferential direction. When the fixed stopper comes into contact with the movable stopper, the movable stopper moves in the groove by being pushed by the fixed stopper. If the arm is pushed to the end of the groove, the arm cannot move any further, so that further rotation of the arm is restricted.

The position at which the arm does not rotate any more becomes a reference position for positioning the rotation axis of the arm, so that the position must be set accurately.
By the way, since the movable stopper moves by contacting the fixed stopper as described above, a collision sound is generated when the movable stopper comes into contact with the fixed stopper. For this reason, the movable stopper is covered with an elastic member such as an elastomer, for example, so that no collision sound is generated when the movable stopper comes into contact with the fixed stopper.

However, in the case of a configuration in which the movable stopper is covered by the elastic member, the elastic member bends at the time of positioning, so that the circumferential dimension of the movable stopper changes. Then, the change in the dimension becomes an error, and there is a possibility that the positioning cannot be performed accurately. Further, since the amount of bending of the elastic member also changes depending on the force pressing the arm, the amount of bending may not be 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 stopper mechanism of a robot that can accurately position while suppressing occurrence of a collision sound 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 coaxial with a rotation axis when the arm rotates and is movable in the circumferential direction, and is provided on the second arm and is fixed to the second arm and the second arm rotates. A fixed stopper 12 that comes into contact with the movable stopper from the circumferential direction.

  The movable stopper is formed of a non-elastic material and has a contact surface with the fixed stopper, and is formed of an elastic material such that when the fixed stopper is pressed against the movable stopper, the fixed stopper comes into contact with the contact surface. And an elastic member for covering 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 by applying a torque enough to allow the elastic member to sufficiently bend. It shows the state where it was turned on. That is, the elastic member protrudes from the contact surface in the circumferential direction when a relatively small force is applied, such as when the elastic member is not in contact with the elastic member. 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, when the movable stopper and the fixed stopper simply come into contact with each other, the elastic member prevents the main body from contacting the fixed stopper. Thereby, it is possible to avoid the generation of the collision sound generated when the main body, which is an inelastic member, and the fixed stopper come into contact.

  On the other hand, when positioning the rotating 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 brought into contact with the contact surface of the main body. Contact In other words, as long as a pressing force enough to expose the contact surface is applied, the circumferential dimension of the movable stopper at the time of positioning matches the width of the main body formed of the inelastic material. Thereby, at the time of positioning, the position of the fixed stopper always becomes the same position, and the determination accuracy is stabilized.

Therefore, in the configuration using the movable stopper, accurate positioning can be performed while suppressing the generation of the collision sound.
According to the second aspect of the invention, the movable stopper has a protrusion protruding from the main body in the circumferential direction, and an end on the protruding side serving as a contact surface. The elastic member covers the movable stopper so as to protrude in the circumferential direction from the projection, and has an opening exposing the projection at a position corresponding to the projection.

  When the main body is covered with the elastic member, if the contact surface of the main body is formed as a uniform flat surface, for example, when the fixed stopper is pressed during positioning, the elastic member may be deformed and enter the contact surface. is there. When the elastic member enters the contact surface, an error may occur because the circumferential dimension of the movable stopper differs according to the pressing force.

Therefore, by providing a convex portion that protrudes in the circumferential direction from the main body, and by using the end surface of the convex portion as a contact surface, when the elastic member is elastically deformed (when contracted in the circumferential direction), the elastic member is The deformation due to the bending is absorbed by the difference in the circumferential position between the main body and the projection.
This prevents the elastic member from entering the contact surface, that is, the circumferential end surface of the convex portion, and prevents an error in the circumferential dimension of the movable stopper. Therefore, it is possible to reduce the possibility that the positioning accuracy is deteriorated.

  According to the third aspect of the present invention, the movable stopper moves within a groove formed in the first arm and having a predetermined length in a circumferential direction, and the convex portion contacts the fixed stopper. , And at a portion that comes into contact with the groove. The elastic member also has an opening that exposes the convex portion at the portion that comes into contact with the groove.

  When the movable stopper moves within the groove, if the protrusion is provided only on the contact surface with the fixed stopper, the above-described error may occur depending on the degree of bending of the elastic member at the portion that contacts the groove. Further, when the movable stopper comes into contact with the groove, a collision noise may be generated.

  For this reason, a convex portion is also formed at a portion that comes into contact with the groove portion, and an opening that exposes the convex portion is formed on the elastic member. And the occurrence of errors in the circumferential dimension of the movable stopper is prevented. Thereby, the possibility that positioning accuracy may deteriorate can be reduced.

According to the fourth aspect of the present invention, the opening of the elastic member is formed so as to become wider as the distance from the projection increases. Thereby, when the elastic member is elastically deformed, a relief portion for releasing the elastic member is formed, and it is possible to reduce a possibility that the elastic member enters the contact surface.
In the invention described in claim 5, the opening is formed with a gap between the opening and the projection. Thereby, when the elastic member is elastically deformed, a relief portion for releasing the elastic member is formed, and it is possible to reduce a possibility that the elastic member enters the contact surface.

FIG. 1 is a diagram schematically illustrating a robot according to an embodiment. The figure which shows an example of the mounting position of a stopper mechanism typically. The figure which shows the principal part of a stopper mechanism typically The figure which shows the structural example of a movable stopper typically FIG. 6 is a diagram showing an example of a contact state between a movable stopper and a fixed stopper in a time series. FIG. 1 schematically shows another configuration example of the movable stopper. FIG. 2 schematically shows 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 the present embodiment has a known configuration as a so-called 6-axis vertical articulated robot, and a shoulder 3 is provided on a base 2 via a first axis (J1). They are connected so as to be rotatable in the horizontal direction. The lower end of a lower arm 4 extending upward through a second shaft (J2) is connected to the shoulder 3 so as to be rotatable in the vertical direction. A first upper arm 5 is connected to a distal end of the lower arm 4 via a third shaft (J3) so as to be rotatable in a vertical direction. A second upper arm 6 is connected to the tip of the first upper arm 5 via a fourth shaft (J4) so as to be able to twist and rotate. A wrist 7 is connected to the distal end 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 able to rotate.

  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 an arm of the robot 1, and the flange 8, which is the tip of the arm, is not shown. However, a hand (also called an end effector) is attached. The hand holds and transfers a work (not shown), and a tool for processing the work is attached to the hand, for example. Each axis (J1 to J6) provided in the robot 1 is provided with a motor (not shown) serving as a driving source corresponding to each axis.

  It should be noted that the first arm and the second arm described in the claims mean having two arms that rotate relatively. Therefore, for example, when the base 2 is the first arm, the shoulder 3 that rotates relatively to the base 2 corresponds to the second arm. When the shoulder 3 is regarded as the first arm, the lower arm 4 or the base 2 that rotates relatively 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 according to 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 movably in a 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. Have been. FIG. 4A shows a state in which the movable stopper 11 is viewed from the inside in the radial direction, and the left-right direction in the drawing corresponds to the circumferential direction. FIG. 4B shows a state where the movable stopper 11 is viewed from the radial direction.

  A plurality of protrusions 20a projecting in the circumferential direction are formed on the main body 20. Although details will be described later, two convex portions 20a provided on the upper side in the figure are portions that come into contact with the fixed stopper 12, and their circumferential end surfaces correspond to the contact surfaces with the fixed stopper 12. . Further, two convex portions 20a provided on the lower side in the figure are portions that come into contact with the inner surface side of the groove portion 13, and their circumferential end surfaces correspond to contact surfaces with the groove portion 13. In the present embodiment, the main body 20 is not formed in a flat plate shape, but formed in a shape curved along the circumferential direction. For this reason, when it comes into contact with the fixed stopper 12 as described later, it comes into contact with a flat surface.

  The main body 20 including the protrusions 20a is made of a metal material that is an inelastic material. The inelastic material means a material having high rigidity that does not need to consider elastic deformation. For this reason, the material is not limited to a metal material, and may be a non-metal material as long as it has almost no elastic deformation. In the present embodiment, the main body 20 is formed of a metal material including the protrusion 20a. Therefore, the width D in the circumferential direction of the main body 20 including the protrusion 20a does not undergo elastic deformation and can be considered to be a substantially constant value. In addition, since the fixed stopper 12 is also formed of a metal material, deformation when the fixed stopper 12 comes into contact with 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. The material of the elastic member 21 is not limited to an elastomer. The elastic member 21 has rectangular openings 21a at positions corresponding to the protrusions 20a of the main body 20, respectively. The opening 21a is formed to have substantially the same size as the protrusion 20a. That is, the elastic member 21 covers the main body 20 in a state where the contact surface (the end face of the convex portion 20a) with the fixed stopper 12 is exposed and in a state where the elastic member 21 protrudes from the convex portion 20a by a distance d in the circumferential direction. ing. That is, the elastic member 21 covers the movable stopper 12 such 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 (the end surface in the circumferential direction; corresponding to the contact surface) of the projection 20a can be visually recognized. Note that the distance d may be appropriately set according to the physical properties of the elastic member 21 and the pressing force for pressing the fixed stopper 12 against the movable stopper 11 (which can be calculated from the torque of the motor) as 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, a holder body 14 provided with a groove 13 and a cover member 15 that covers the groove 13 with a part of the groove 13 opened are provided on the base 2 side. The movable stopper 11 is disposed so as to be freely movable in the groove 13 in a state in which the step portion 11a is closed from above by the cover member 15.

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 at the center side of the groove 13 (a position not in contact with the end of the groove 13) from the circumferential direction as indicated by an arrow X. It is assumed 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 just by the contact between the movable stopper 11 and the fixed stopper 12, so that 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 rotating shaft, a pressing force for pressing the fixed stopper 12 against the movable stopper 11 is used. As a result, the amount of deflection of the elastic member 21 increases.

  When the amount of deflection of the elastic member 21 (the amount of compression or deformation of the elastic member 21 in the case of the present embodiment) exceeds the above-described distance d (see FIG. 3), the movable stopper 11 becomes convex on the fixed stopper 12 side. The portion 20a directly contacts the fixed stopper 12, and the opposite convex portion 20a in the circumferential direction directly contacts the end of the groove 13. 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 20 and the protrusion 20a because the elastic member 21 contracts in the circumferential direction.

At this time, as described above, since the main body 20 and the protrusion 20a have high rigidity, when the elastic member 21 is bent by the distance d, the distance from the end of the groove 13 to the fixed stopper 12 is equal to the protrusion 20a. And the width D of the main body 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 comes into contact from the opposite side to the case of FIG.
As described above, the stopper mechanism 10 suppresses the generation of the collision sound at the time of mere contact, but can precisely define the position when positioning the rotating shaft.

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

The movable stopper 11 is formed of an inelastic material, has a 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 is formed of an elastic material and fixed. An elastic member 21 covering the movable stopper 12 so that the stopper 12 comes into contact with the contact surface of the movable stopper 11.
Thereby, when the movable stopper 11 and the fixed stopper 12 simply come into contact with each other, the contact between the main body 20 and the fixed stopper 12 is prevented by the elastic member 21, and the generation of a collision sound can be avoided.

  On the other hand, when positioning the rotating shaft, the fixed stopper 12 is strongly pressed against the movable stopper 11, so that the pressing force causes the elastic member 21 to bend and the fixed stopper 12 to contact the contact surface of the main body 20. Become. At this time, since the main body 20 is formed of an inelastic material, it does not elastically deform. As a result, the fixed stopper 12 does not rotate any more.

  With such a configuration, even in a configuration in which the elastic member 21 is provided on the movable stopper 11, the circumferential dimension of the movable stopper 11 at the time of positioning can be adjusted as long as a pressing force enough to expose the contact surface is applied. The width of the portion 20 (in the present 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, accurate positioning can be performed while suppressing the generation of collision noise.
The movable stopper 11 has a protrusion 20a that protrudes from the main body 20 in the circumferential direction, and an end on the protruding side serves as a contact surface. The elastic member 21 covers the movable stopper 11 so as to protrude in the circumferential direction from the protrusion 20a, and has an opening 21a at a position corresponding to the protrusion 20a to expose the protrusion 20a. ing.

  In the case of a configuration in which the main body 20 is covered with the elastic member 21 as in the present embodiment, if the contact surface of the main body 20 is formed as, for example, a uniform flat surface, the elastic stopper 21 is pressed when the fixed stopper 12 is pressed during positioning. The member 21 may be deformed and enter the contact surface. Then, 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, by providing a convex portion 20a that protrudes in the circumferential direction from the main body portion 20 and using the end surface of the convex portion 20a as a contact surface, when the elastic member 21 is elastically deformed (when contracted in the circumferential direction), The deformation due to the bending of the elastic member 21 is absorbed by the difference between the positions of the main body 20 and the protrusions 20a in the circumferential direction.
Accordingly, the elastic member 21 is prevented from entering the contact surface, that is, the circumferential end surface of the projection 20a, and an error in the circumferential dimension of the movable stopper 11 is prevented. Therefore, it is possible to prevent the possibility that the positioning accuracy is deteriorated.

Further, the movable stopper 11 moves within a groove 13 having a predetermined length in a circumferential direction formed on the first arm, and the convex portion 20a has a portion that comes into contact with the fixed stopper 12, and It is formed at a portion that comes into contact with the groove 13. The elastic member 21 has an opening 21a that exposes the projection 20a at a position that comes into contact with the groove 13.
In the case where the movable stopper 11 moves in the groove 13, if the protrusion 20 a is provided only on the contact surface with the fixed stopper 12, the above-described error may occur depending on the degree of bending of the elastic member 21 at the portion in contact with the groove 13. May occur.

  Therefore, the convex portion 20a is also formed at the portion that comes into contact with the groove portion 13, and the opening portion 21a that exposes the convex portion 20a is formed on the elastic member 21, so that the side that comes into contact with the fixed stopper 12 comes into contact with the groove portion 13. No dimensional errors can occur on both sides. Therefore, it is possible to prevent the possibility that the positioning accuracy is deteriorated.

  In the case of the present embodiment, the stopper mechanism 10 is provided at a joint between the base 2 and the shoulder 3. When the shoulder 3 rotates, the amount of movement of the robot 3 increases as the robot 1 moves. That is, if the positioning of the rotation axis (J1) of the shoulder 3 is not performed correctly, a large error occurs at the hand of the robot 1. Therefore, 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 accuracy of the operation of the robot 1 can be improved. Can be prevented from becoming worse.

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

The present invention is not limited to the embodiments described above and illustrated in the drawings, and various modifications and extensions can be made without departing from the gist thereof.
In the embodiment, the quadrangular prism-shaped protruding 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 flat, the size and shape of the tip side and the root (the end on the side of the main body 20) may be different.

In the embodiment, the example in which the stopper mechanism 10 is provided at the joint between the base 2 and the shoulder 3 is shown, but the stopper mechanism 10 may be provided at another joint.
Although the embodiment has exemplified the 6-axis vertical articulated robot, 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. If it is a robot, it 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 projection 20a is formed in the elastic member 21. However, for example, as shown in FIG. , May be formed so as to become wider as the distance from the projection 20a increases. Thereby, when the elastic member 21 is elastically deformed, the possibility that the elastic member 21 enters the contact surface can be reduced.
In this case, the position in contact with the protrusion 20a may be closer to the main body 20 than the contact surface (the end surface on the circumferential side of the protrusion 20a). Thus, when the elastic member 21 is elastically deformed, the possibility that the elastic member 21 enters the contact surface can be further reduced.

As shown in FIG. 6B, the opening 21a may be formed with a gap between the opening 21a and the projection 20a. In this case, the inner surface of the opening 21a and the side surface of the protruding portion 20a (the vertical surface of the protruding portion 20a in the drawing) function as a relief portion, and the possibility that the elastic member 21 invades 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 protrusion 20a increases, and to have a gap between the opening 21a and the protrusion 20a. . Even with such a configuration, the possibility that the elastic member 21 enters the contact surface can be reduced.

  Further, as shown in FIG. 7A, the opening 21a may have a circular shape. In this case, the shape of the opening 21a may be elliptical or triangular in accordance with the shape of the projection 20a. Further, as shown in FIG. 7B, one opening 21a may be formed corresponding to the plurality of projections 20a.

  In the drawing, 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 main body (contact surface), and 20a is convex. Portions (contact surfaces), 21, 30, and 40 indicate elastic members, and 21a indicates an opening.

Claims (6)

A robot stopper mechanism that defines a rotation range of a second arm that rotates relatively 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, the fixed stopper being fixed to the second arm, and coming into contact with the movable stopper in a circumferential direction when the second arm rotates,
The movable stopper,
A main body formed of an inelastic material and having a contact surface with the fixed stopper;
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;
It is constituted by,
The elastic member projects from the contact surface in a state before the fixed stopper is pressed against the movable stopper, while the fixed stopper is in contact with the contact surface in a state in which the fixed stopper is pressed against the movable stopper. Robot stopper mechanism that comes into contact with the robot. 2. The elastic member according to claim 1, wherein the elastic member is provided at a position sandwiching the contact surface, and contacts the fixed stopper at a position sandwiching the contact surface when the fixed stopper is pressed against the movable stopper. 3. Robot stopper mechanism. The movable stopper has a protrusion protruding in the circumferential direction from the main body, and an end of the protruding side serving as the contact surface,
The said elastic member covers the said movable stopper in the state which protrudes in the circumferential direction from the said convex part, The opening which exposes the said convex part is formed in the position corresponding to the said convex part. 3. The stopper mechanism of the robot according to 1 or 2. The movable stopper moves in a groove having a predetermined length in a circumferential direction formed on the first arm,
The convex portion is formed at a portion that contacts the fixed stopper, and at a portion that contacts the groove portion,
4. The stopper mechanism of the robot according to claim 3, wherein the elastic member has an opening that exposes the convex portion at a portion that contacts the groove. 5. 5. The stopper mechanism according to claim 3, wherein the opening of the elastic member is formed to be wider as the distance from the protrusion increases. 6. The stopper mechanism for a robot according to claim 3, wherein the opening of the elastic member is formed with a gap between the opening and the protrusion.

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