JP2019206038A - Robot arm mechanism - Google Patents

Abstract

To provide a robot arm mechanism that improves safety of an end effector so as to secure its reliability and that achieves safety measures eliminating an interference with an operation of the end effector.SOLUTION: A robot arm mechanism includes: a support part 2; an arm 5 that is movably supported by the support part; a wrist part 6 that is provided at the tip of the arm; an end effector 8 that is attached to the tip of the wrist part and that has fingers 81 and 82; and a cylindrical cover 9 for covering at least the whole of the fingers 81 and 82 of the end effector.SELECTED DRAWING: Figure 8

Description

  Embodiments described herein relate generally to a robot arm mechanism.

  Conventionally, articulated robot arm mechanisms have been used in various fields such as industrial robots. The inventors have achieved practical application of a linear motion expansion / contraction mechanism (Patent Document 1). This linear motion expansion / contraction mechanism expands the range of motion of the polar coordinate robot arm mechanism to improve practicality, and since there is no elbow indirect, it is safe and eliminates the need for a safety fence, and is installed next to the worker. It is a very useful structure that can realize collaborative work with.

  Thus, the robot arm mechanism installed next to the worker is required to have higher safety in every detail. For example, when the robot hand is attached to the wrist at the tip of the arm as an end effector, not only the robot hand itself but also the robot hand itself so that its fingers, hands, arms, and other parts are not caught in the robot hand's pongger, It is necessary to take safety measures so that it does not come into contact with Fonger. For this reason, it is conceivable to attach a contact sensor or proximity sensor in the vicinity of Fonger or in the vicinity thereof, but a reduction in safety due to malfunction cannot be completely eliminated. Also, specifications that do not disturb the operation of the robot hand mechanically or software are required.

Japanese Patent No. 5435679

  The purpose is to realize safety measures that improve the safety of the end effector in the robot arm mechanism, ensure its reliability, and do not hinder the operation of the end effector.

  The robot arm mechanism according to the present embodiment includes a support column, an arm that is movably supported by the support column, a wrist unit that is equipped at the tip of the arm, and an end that has a finger that is attached to the tip of the wrist. An effector and a cylindrical cover that covers at least the entire finger of the end effector are provided.

FIG. 1 is an external perspective view of a robot arm mechanism according to the present embodiment. FIG. 2 is a side view of the robot arm mechanism of FIG. FIG. 3 is a diagram showing an internal structure of the robot arm mechanism of FIG. FIG. 4 is a diagram showing the robot arm mechanism of FIG. FIG. 5 is a perspective view showing an example of a robot hand as an end effector attached to the wrist portion of FIG. FIG. 6 is a side view of the robot hand of FIG. FIG. 7 is a perspective view of a cover of the robot hand of FIG. FIG. 8 is a side view of the cover of FIG. FIG. 9 is a perspective view of a cover according to a modification of FIG. FIG. 10 is a side view of the cover of FIG. FIG. 11 is a perspective view of a cover according to another modification of FIG. 12 is a side view of the cover of FIG. FIG. 13 is a perspective view of a cover according to still another modification of FIG. FIG. 14 is a side view of the cover of FIG. FIG. 15 is a perspective view according to a modification of the cover of FIG. FIG. 16 is a perspective view according to a modification of the cover of FIG.

Hereinafter, the robot arm mechanism according to the present embodiment will be described with reference to the drawings.
1 and 2 are external views of a robot arm mechanism according to the present embodiment. FIG. 3 shows the internal structure of the linear motion extension / contraction mechanism. FIG. 4 shows the robot arm mechanism with a graphic symbol. The robot arm mechanism according to the present embodiment has a plurality of, here, six joint portions J1, J2, J3, J4, J5, and J6. The plurality of joint portions J1, J2, J3, J4, J5, and J6 are sequentially arranged from the base 1. In general, the first, second, and third joint portions J1, J2, and J3 are referred to as the root three axes, and the fourth, fifth, and sixth joint portions J4, J5, and J6 are mainly end effectors (hand effect). This is called the wrist 3 axis that changes the posture of the genitalia. The first joint portion J1 is a torsional joint for turning, and the third joint portion J3 is a linear motion extension mechanism. Therefore, the robot arm mechanism according to this embodiment is configured as a polar coordinate robot arm mechanism.

  The first joint portion J1 is a torsion joint centered on a first rotation axis RA1 perpendicular to the ground contact surface of the base 1. The second joint portion J2 is a bending joint centered on the second rotation axis RA2 arranged perpendicular to the first rotation axis RA1. The third joint portion J3 is a linear motion expansion / contraction mechanism in which the arm portion 5 expands and contracts linearly about a third axis (moving axis) RA3 arranged perpendicular to the second rotation axis RA2. The fourth joint portion J4 is a torsional joint centered on the fourth rotation axis RA4 that substantially coincides with the third movement axis RA3. The fifth joint portion J5 is a bending joint centered on the fifth rotation axis RA5 arranged perpendicular to the fourth rotation axis RA4. The sixth joint portion J6 is a bending joint centered on the sixth rotation axis RA6 that is disposed perpendicular to the fourth rotation axis RA4 and the fifth rotation axis RA5.

  As shown in FIG. 4, the second joint portion J2 is offset with respect to the first joint portion J1 with respect to two directions of the rotation axis RA1 and an axis orthogonal to the rotation axis RA1. The rotation axis RA2 of the second joint portion J2 does not intersect the rotation axis RA1 of the first joint portion J1. The third joint portion J2 is offset with respect to the second joint portion J2 with respect to two directions of the rotation axis RA1 and an axis orthogonal to the rotation axis RA1. The rotation axis RA3 of the third joint portion J3 does not intersect the rotation axis RA2 of the second joint portion J2. One bending joint part of the base three axes of the plurality of joint parts J1-J6 is replaced with a linear motion expansion / contraction joint part J3, and the second joint part J2 is offset in two directions with respect to the first joint part J1, By offsetting the third joint portion J3 in two directions with respect to the second joint portion J2, the robot arm mechanism eliminates the singularity posture structurally.

  A base 1 of the robot arm mechanism is provided with a support column 2 that roughly forms a cylindrical body. The support column 2 is separated vertically, and the upper frame 21 of the support column lower portion 31 and the upper frame 22 of the support column upper portion 32 are connected by the first joint portion J1. The first joint portion J1 includes a torsional rotation axis RA1. The rotation axis RA1 is, for example, parallel to the vertical direction. The arm portion 5 pivots horizontally by the rotation of the first joint portion J1. The column lower part 31 is connected to the fixed part of the first joint part J1. The upper frame 22 is connected to the rotating portion of the first joint portion J1, and rotates about the rotation axis RA1. First and second frame rows 51 and 52 of a third joint portion J3 to be described later are housed in the hollow interiors of the frames 21 and 22 of the column portion 2 that forms a cylindrical body. On the frame 22 of the column upper part 32, the undulating part 4 that houses the second joint part J2 is installed. The rotation axis RA2 of the second joint portion J2 is, for example, horizontal. The undulating portion 4 has a pair of side frames 23 as a fixing portion of the second joint portion J2. The pair of side frames 23 are placed on the upper frame 22. The pair of side frames 23 supports a cylindrical body 24 as a rotating portion of the second joint portion J2 that also serves as a motor housing. A support portion (feeding mechanism) 25 is attached to the peripheral surface of the cylindrical body 24. The delivery mechanism 25 supports a roller unit 58, a drive gear 56, and a guide roller 57. The delivery mechanism 25 supports the first and second frame rows 51 and 52 so as to be movable back and forth, and also moves the first and second frames 53 and 54 when the first and second frame rows 51 and 52 move forward. When the first and second frame rows 51 and 52 are pulled back, the first and second frames 53 and 54 are separated. As the cylindrical body 24 rotates, the delivery mechanism 25 rotates, and the arm portion 5 supported by the roller unit 58 of the delivery mechanism 25 is raised and lowered.

  The linear motion expansion / contraction mechanism that forms the third joint portion J3 has a structure newly developed by the inventors, has a limited linear motion range, and has a pull-in range that is the same length as the linear motion range. It is clearly distinguished from a solid linear joint. When the first and second frame trains 51 and 52 are fed forward from the feed mechanism 25, the first and second frame rows 51 and 52 are configured as arm portions (columnar bodies) 5 with linear rigidity secured along the center axis (extension / retraction center axis RA 3). The When the first and second frame rows 51 and 52 are pulled back to the feed mechanism 25, they are returned to a state in which they can be bent behind the roller unit 58.

  The first frame row 51 is composed of a plurality of first frames 53 that are connected to be freely bent. Typically, the first frame 53 is formed in a substantially flat plate shape. The first frame 53 is not limited to a flat plate shape, and may be a grooved body or a cylindrical body. Further, the cross-sectional shape of the first frame 53 is a square shape such as a U-shape or a square shape. The shape is not limited to (rectangular), and may be a polygonal shape such as a triangle or a pentagon, a circular shape, an elliptical shape, or an arc shape in which a part of the circular shape or the elliptical shape is cut out. Here, the first frame 53 will be described as having a substantially flat plate shape.

  The second frame row 52 is composed of a plurality of second frames 54 that are flexibly connected. The second frame 54 typically forms a groove having a U-shaped cross section. The second frame 54 is not limited to a groove-like body having a U-shaped cross section, and other various groove-like or cylindrical bodies having a cross-sectional shape can be adopted. For example, the second frame 54 may be a cylindrical body having a rectangular cross section. The second frame 54 is a groove or cylinder, and its cross-sectional shape is not limited to a quadrangle (rectangle), but a polygon such as a triangle or pentagon, and a circle, ellipse, circle or ellipse. An arc shape in which a part of the arc is cut off may be used. Here, the second frame 54 is described as being configured as a groove-shaped body having a U-shaped cross section.

  As will be described later, the first frame 53 and the second frame 54 are joined. Under the above-described shapes of the first frame 53 and the second frame 54, the overall shape of the cross section in a state where the first frame 53 and the second frame 54 are joined is a quadrangle, a triangle, a rhombus, or a trapezoid. , Other polygons, H-shape, circle and ellipse.

  The second frame 54 is connected to bendable between the bottom plates. The bending of the second frame row 52 is limited at a position where the end surfaces of the side plates of the second frame 54 come into contact with each other. At that position, the second frame row 52 is linearly arranged. The first first frame 53 in the first frame sequence 51 and the first second frame 54 in the second frame sequence 52 are connected by a combined frame 55.

  The connecting piece 55 is a block having a shape in which the upper part protrudes rearward from the lower part. The protrusion length with respect to the upper part and the lower part is half the length of the second frame 54. The upper part has the same thickness as the first frame 53 and the lower part has the same thickness as the second frame 54. The top first frame 53 is connected to the upper part so that it can be bent, and the top second frame 54 is connected to the lower part so that it can be bent. The connection position between the first frames 53 is shifted by ½ length with respect to the connection position between the second frames 54. The open / close position (connection position) of the front and rear second frames 54 is located at the front and rear center of the first frame 53. This position is equipped with a lock mechanism which will be described later.

  The first and second frame rows 51 and 52 are pressed and joined to the upper and lower rollers 59 of the rectangular cylindrical roller unit 58. The joined first and second frame rows 51 and 52 constitute a columnar arm portion 5. If the first and second frames 53 and 54 have the above-described typical cross-sectional shapes, the first and second frames 53 and 54 are rigidly joined to form a linear columnar body. However, if the planar shape of the first and second pieces 53 and 54 is a trapezoidal shape or a partial shape of an annular shape, the first and second pieces 53 and 54 are hardened by joining to form curved columnar bodies. Eggplant.

  A drive gear (pinion) 56 is provided behind the row of rollers 59. The drive gear 56 is connected to a motor (not shown) via a speed reducer. A linear gear (not shown) is provided across the front and rear in the center of the inner wall of the first frame 53. When the plurality of first frames 53 are aligned in a straight line, the front and rear linear gears are connected in a straight line to form a long linear gear (rack). The drive gear (pinion) 56 is meshed with a linear linear gear. The linear gear connected in a straight line forms a rack and pinion mechanism together with the drive gear 56. When the drive gear 56 rotates forward, the arm portion 5 extends forward. When the drive gear 56 rotates in the reverse direction, the arm portion 5 is pulled back into the undulating portion 4 and contracts. The first and second frame rows 51 and 52 that are pulled back to the rear of the roller unit 58 and released from the pressing by the upper and lower rollers 59 are separated from each other. The separated first and second frame rows 51 and 52 are returned to a bendable state. The first and second frame rows 51, 52 that have returned to the bendable state are bent in the same direction (the bottom plate side of the second frame 54) in the undulating portion 4, and are housed inside the column portion 2. At this time, the first frame row 51 is stored in a state substantially parallel to the second frame row 52.

  A wrist portion 6 is attached to the tip of the arm portion 5. The wrist 6 is equipped with fourth to sixth joints J4 to J6. The fourth to sixth joint portions J4 to J6 include three orthogonal rotation axes RA4 to RA6. The fourth joint portion J4 is a torsional rotary joint centered on a fourth rotation axis RA4 that substantially coincides with the expansion / contraction center axis RA3, and the end effector is swung and rotated by the rotation of the fourth joint portion J4. The fifth joint portion J5 is a bending rotation joint about the fifth rotation axis RA5 arranged perpendicular to the fourth rotation axis RA4, and the end effector is tilted back and forth by the rotation of the fifth joint portion J5. Is done. The sixth joint portion J6 is a torsional rotational joint about the sixth rotational axis RA6 that is arranged perpendicular to the fourth rotational axis RA4 and the fifth rotational axis RA5. By the rotation of the sixth joint portion J6, The end effector is pivoted.

  The end effector is attached to, for example, a disk-shaped adapter 7 provided in the rotating portion lower portion 11 of the sixth joint portion J6 of the wrist portion 6. The end effector is moved to an arbitrary position by the first, second, and third joint portions J1, J2, and J3, and is changed to an arbitrary posture by the fourth, fifth, and sixth joint portions J4, J5, and J6. In particular, the length of the expansion / contraction distance of the arm portion 5 of the third joint portion J3 enables the end effector to reach a wide range of objects from the proximity position of the base 1 to the remote position. The third joint portion J3 is characterized by a linear expansion / contraction operation realized by a linear motion expansion / contraction mechanism constituting the third joint portion J3 and a length of the expansion / contraction distance.

  5, 6 (a), and 6 (b) show a two-fingered robot hand that grips a workpiece with, for example, a plurality of, typically a pair of fingers 81, 82 as end effectors. . As is well known, the end effector includes a portion (referred to as an action portion or a movable portion) that directly acts on a workpiece (work object). In the robot hand 8, fingers 81 and 82 that move toward and away from each other (open and close) as an action part or a movable part. Needless to say, an end effector having various action parts such as a vacuum suction part and an electromagnet, or a movable part can be applied instead of the robot hand 8.

  A main body (gripper) 80 of the robot hand 8 is provided so that a pair of finger bases can move in a direction in which the linear guide mechanism approaches / separates. A pair of fingers 81 and 82 are attached to the pair of finger bases, respectively. The inter-finger distance between the pair of fingers 81 and 82 varies depending on the movable range (stroke) of the pair of finger bases. For example, the minimum inter-finger distance between the pair of fingers 81 and 82 is determined according to the size of the gripping object (work), and the attachment positions of the fingers 81 and 82 to the finger base are adjusted accordingly. The total width (outer width, outer dimension) of the pair of fingers 81, 82 when the pair of fingers 81, 82 are most separated is the distance between one outer surface of the pair of fingers 81, 82 to the other outer surface. The distance (maximum width) is expressed as Wmax, and the total width of the pair of fingers 81 and 82 when the pair of fingers 81 and 82 are closest to each other is expressed as Wmin.

  As shown in FIGS. 7 and 8, the hand cover 9 has a length that covers at least the entire fingers (movable parts) 81 and 82 of the end effector to the tip thereof, and is larger than the maximum width Wmax of the pair of fingers 81 and 82. It is constructed in a cylindrical shape with a slightly longer inner diameter (inner dimension). The tip portion of the hand cover 9 is opened with a diameter that allows the whole or part of the object to be gripped to pass through the hand cover 9.

  The cylindrical shape is defined as a hollow shape that is large enough to allow the object to be grasped (work) to be conducted and has a leading end that is open and a rear end that is opened as a portion attached to the gripper 80 or the adapter 7. The shape is not limited, and includes a rectangular tube shape, and further includes a hemispherical shape, a box shape, and the like.

  Since the fingers 81 and 82 are covered to the tip by the hand cover 9, the fingers, hands, arms, and other parts of the worker always come into contact with the hand cover 9 before contacting the fingers 81 and 82. Therefore, it is possible to avoid the situation where the fingers, hands, arms, and other parts of the worker are caught between the fingers 81 and 82, and it is possible to greatly improve safety, as well as electrical and software using proximity sensors and contact sensors. Since this is not a practical measure, there is essentially no risk of malfunction, and the reliability can be stably secured at a high level. The hand cover 9 does not interfere with the task of picking up, transferring and releasing the object to be grasped by the fingers 81 and 82.

  The concept of the present invention is that the cover 9 covers the entire movable part (acting part) such as the end effector fingers 81 and 82 up to the tip thereof together with the whole or a part of the object to be grasped with high reliability. It is to ensure a level of safety. The category of this concept includes that the cover 9 has various shapes other than the cylindrical shape. For example, the cover 9 is not limited to a cylindrical shape, and may be a rectangular tube shape such as a triangle, a square, a pentagon, a hexagon, and an octagon, or a hemispherical shape, a box shape, or the like according to the shape of the object to be grasped. It may be. Further, it has been described above that the inner dimension of the cover 9 is slightly longer than the maximum width Wmax of the fingers 81 and 82, but the inner dimension of the cover 9 is significantly larger than the maximum width Wmax of the fingers 81 and 82 depending on the dimension of the object to be grasped. It may be long. Further, the cover 9 covers the movable parts (acting parts) such as the fingers 81 and 82 of the end effector up to the tip thereof, but the movable parts (acting parts) such as the fingers 81 and 82 are grippers of the end effector. It may be calibrated so as to cover with the main body 80 such as the end effector. This will be specifically described below.

  As shown in FIGS. 9 and 10, the hand cover 9-1 has a shape in which a cylindrical portion and a conical portion having an inner diameter longer than the diameter of the grasped object 101 larger than the maximum width Wmax of the pair of fingers 81 and 82 are combined. It is. From the viewpoint of realizing a smooth picking task, the inner diameter of the hand cover 9-1 is preferably in the range of 1.5 to 3 times the maximum width Wmax of the pair of fingers 81 and 82.

  Further, as shown in FIGS. 11 and 12, when the gripping object 102 is, for example, a rod or a rectangular parallelepiped that is long in the front-rear direction, the hand cover 9-2 is a box having an inner dimension that is slightly longer than the length and width of the gripping object 102. Configured in shape.

  13 and 14, the hand cover 9 may have a cylindrical shape with a length that covers the main body (gripper) 80 together with the fingers 81 and 82. Further, the hand cover 9 is typically cylindrical with a constant diameter, but the tip end portion 91 is stepped as shown in FIG. 15 or the tip portion 92 is conically widened as shown in FIG. It may be a thing. In that case, it is possible to cope with various shapes and movements of the action portion such as the hand of the end effector.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  8 ... Robot hand, 9 ... Hand cover, 80 ... Gripper, 81, 82 ... Finger.

Claims (10)

A strut,
An arm supported movably on the support column;
A wrist equipped at the tip of the arm;
An end effector having a movable part attached to the tip of the wrist part;
A robot arm mechanism comprising: a cylindrical cover that covers at least the entire movable portion of the end effector.   2. The robot arm mechanism according to claim 1, wherein the cover has an inner diameter longer than a maximum width of the movable part so as not to interfere with the movable part.   The robot arm mechanism according to claim 2, wherein the end effector is a gripping robot hand that grips an object to be gripped by at least a pair of fingers.   2. The robot arm mechanism according to claim 1, wherein the cover has a cylindrical shape or a rectangular tube shape.   The robot arm mechanism according to claim 4, wherein the cover has a shape that expands in a stepped or conical shape toward the front.   2. The robot arm mechanism according to claim 1, wherein the cover is made of a flexible material. A strut,
An arm supported movably on the support column;
A wrist equipped at the tip of the arm;
An end effector attached to the tip of the wrist;
A robot arm mechanism comprising a cylindrical cover that covers the end effector up to the tip thereof. A strut,
An arm supported movably on the support column;
A wrist equipped at the tip of the arm;
An end effector attached to the tip of the wrist and gripping a gripping object by the gripping portion;
A robot arm mechanism comprising: a cover that covers the entire gripping portion together with at least a part of the gripping object. Moving parts;
A main body for supporting the movable part;
A robot hand comprising a cover having a cylindrical shape covering the entire movable portion.   An end effector cover having a movable part, which can be attached to a robot arm or a wrist part mounted on the tip of the robot arm, and has a cylindrical shape covering the entire movable part. .

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