Robot hand

Abstract

A robot hand according to one aspect of the present disclosure can be equipped and used at a tip end of various types of robot arms, such as vertically articulated, horizontally articulated, or polar coordinate types. The robot hand has a base portion attached to the tip end of the robot arm. A plurality of gripping portions are supported on the base portion. The plurality of gripping portions are fixed to the base portion. Center lines of the plurality of gripping portions are inclined in directions that move away from each other toward the front.

Description

Robot Hand

[0001] The present disclosure relates to a robot hand.

[0002] Among robot hands attached to robots, there are those equipped with a plurality of gripping parts suitable for respective characteristics in order to handle various types of work (for example, Patent Document 1). Generally, these plurality of gripping parts are often fixedly arranged side by side, fixedly arranged in an L-shape along two orthogonal axes, or attached to a tool changer. In any case, a robot hand having a plurality of gripping parts is inevitably larger than a robot hand equipped with a single gripping part, and thus there is concern about interference with peripheral devices. For example, in the case of a robot hand in which two types of gripping parts are fixedly arranged side by side, when the posture of the robot hand is changed so that a work can be gripped by one of the gripping parts, the other gripping part may interfere with a container that houses the work. In the case of a robot hand in which two types of gripping parts are fixedly arranged in an L-shape, the rotational angle of a rotary joint close to the robot hand may have to be restricted physically or in software so that the robot hand itself does not interfere with the robot. In the case of a robot hand having a tool changer equipped with a plurality of types of gripping parts, the operation time of the tool changer for switching the gripping part to be used occurs, and thus the cycle time increases.

[0003] Japanese Patent Application Laid-Open No. 7-285090

[0004] An object is to provide a robot hand that can handle a plurality of types of work.

[0005] A robot hand according to an aspect of the present disclosure has a base part attached to the tip of a robot arm and a plurality of gripping parts supported by the base part. The gripping parts are fixed to the base part, and their respective center lines are inclined in a direction away from each other forward.

[0006] Figure 1 is a diagram showing a robot arm mechanism equipped with the robot hand according to this embodiment. Figure 2 is a perspective view of the robot hand of Figure 1. Figure 3 is a front view of the robot hand of Figure 2. Figure 4 is a tilted view of the robot hand of Figure 3. Figure 5 is a diagram that assists in explaining the effects exhibited by the robot hand according to this embodiment. Figure 6 is a diagram that assists in explaining the effects exhibited by the robot hand according to this embodiment. Figure 7 is a front view of the robot hand according to the first modification of this embodiment. Figure 8 is a front view of the robot hand according to the second modification of this embodiment. Figure 9 is a front view of the robot hand according to the third modification of this embodiment.

[0007] The robot hand according to this embodiment (hereinafter simply referred to as the robot hand) will be described below with reference to the drawings. In the following description, components having substantially the same function and configuration will be denoted by the same reference numerals, and redundant explanations will be given only when necessary.

[0008] The configuration of the robot hand 1 will be described below with reference to Figures 1 to 3. As shown in Figure 1, the robot hand 1 is attached to the tip (wrist portion 91) of various types of robot arms 9, such as vertical articulated type, horizontal articulated type, and polar coordinate type, and is used for this purpose. The robot hand 1 has multiple types of gripping parts so that it can grip multiple types of workpieces. The multiple types of gripping parts differ in at least one of the following: gripping method, size of the gripping part, or material constituting the gripping part. Gripping methods include methods of holding the workpiece by physically gripping it and methods of holding the workpiece by suction. Examples of gripping parts that hold the workpiece by physically gripping it include those with multiple fingers, such as two fingers or three fingers, and those with a wire that grips the workpiece. Examples of gripping parts that hold the workpiece by suction include those that utilize vacuum, suction, magnetism, fluid, and static electricity.

[0009] In this embodiment, it is assumed that two types of workpieces 100 and 200 housed in a container 300 are grasped by a robot hand 1. The first workpiece 100 has a smooth surface and is relatively heavy. The second workpiece 200 has an uneven surface and is relatively light. The robot hand 1 has a first suction pad 15, which is a rectangular plate shape with a single suction hole, as a gripping part for grasping the first workpiece 100, and a second suction pad 16, which is a rectangular plate shape with multiple suction holes, as a gripping part for grasping the second workpiece 200.

[0010] As shown in Figures 2 and 3, the robot hand 1 has a rectangular base plate 10 as a base portion attached to the tip of the robot arm 9. A circular adapter plate 11 is provided on the surface of the base plate 10 as a connecting portion for connecting to the tip of the robot arm 9. On the back side of the base plate 10, a first suction pad 15 is supported via a first support base 13, and a second suction pad 16 is supported via a second support base 14. On the back side of the base plate 10, the two types of suction pads 15 and 16 are arranged side by side along a uniaxial direction. Typically, the two types of suction pads 15 and 16 are arranged side by side at equidistant positions from the base plate 10. This means that the center positions of the respective suction surfaces of the two types of suction pads 15 and 16 are equidistant from the base plate 10. Of course, one of the two types of suction pads 15 and 16 may be arranged to protrude forward.

[0011] In Figures 2 and 3, the three orthogonal axes of the hand coordinate system, with the robot hand 1 as the reference, are defined as follows. For example, when defined by the base plate 10, the width direction of the base plate 10 is the X-axis, the length (depth) direction of the base plate 10 is the Y-axis, and the thickness direction of the base plate 10 is the Z-axis. The Z-axis is parallel to a straight line (also called the center line of the base plate 10) that passes through the center point of the surface of the base plate 10 and is perpendicular to the base plate 10. The direction of the Z-axis is also called the front-to-back direction of the robot hand 1. In the robot hand 1, "front" is the direction along the Z-axis, and is the direction from the adapter plate 11 (base plate 10) connected to the robot arm 9 toward the suction pads 15 and 16. When the base part is not plate-shaped, the three orthogonal axes are defined as the Z-axis, which is perpendicular to the adapter plate 11 (mounting surface of the robot arm), and the X-axis and Y-axis, which are mutually perpendicular to the Z-axis. In this case, the center line of the base part is a straight line that passes through the center point of the adapter plate 11 and is parallel to the Z-axis. As described later, the center line of the suction pad is a straight line that passes through the center point of the pad surface (suction surface) of the suction pad and is perpendicular to the pad surface.

[0012] As shown in Figure 3, in a front view, the first suction pad 15 is fixed to the base plate 10 via the first support base 13 such that its centerline 15L is inclined outward at an angle θ1 relative to the centerline 10L of the base plate 10, and the second suction pad 16 is fixed to the base plate 10 via the second support base 14 such that its centerline 16L is inclined outward at an angle θ2 relative to the centerline 10L of the base plate 10. Note that the inclination of the first suction pad 15 outward with respect to the centerline 10L of the base plate 10 means that, in a front view, the centerline 15L of the first suction pad 15 is inclined in a direction away from the centerline 10L of the base plate 10 toward the front. At this time, the pad surface of the first suction pad 15 faces outward. Note that when the robot hand 1 is viewed in three dimensions rather than from a front view, it is described as follows. Specifically, the first suction pad 15 is fixed to the base plate 10 via the first support base 13 such that its centerline 15L is inclined outward at an angle θ1 with respect to the center plane of the base plate 10. The second suction pad 16 is fixed to the base plate 10 via the second support base 14 such that its centerline 16L is inclined outward at an angle θ2 with respect to the center plane of the base plate 10. The center plane of the base plate 10 is defined as a plane parallel to the YZ plane and containing the centerline 10L of the base plate 10. In other words, the suction pads 15 and 16 are inclined only around the Y axis.

[0013] As shown in Figure 3, for example, the first suction pad 15 and the second suction pad 16 are positioned symmetrically with respect to the center line 10L (center plane of the base plate 10) of the base plate 10 such that their inclination angles θ1 and θ2 coincide. In this case, it is desirable that the inclination angles θ1 and θ2 are greater than 0 degrees and less than 45 degrees, respectively. The reason for this will be explained later. Of course, the first suction pad 15 and the second suction pad 16 may be positioned so that their inclination angles θ1 and θ2 do not coincide.

[0014] The effects of the robot hand 1 according to this embodiment will be described below with reference to Figures 4 to 6. One feature of the robot hand 1 is that two types of gripping parts (a first suction pad 15 and a second suction pad 16) are fixed to the base plate 10. This feature allows the gripping part to be switched using only the movement of the robot arm 9. The gripping part to be used can be switched using only a change in the posture of the robot arm, without requiring a complex mechanism such as a tool changer with multiple gripping parts attached, or a drive source such as a motor to drive the tool changer. Moreover, as will be described later, since the multiple gripping parts are inclined outward with respect to the center line 10L of the base plate 10 to the extent that their respective center lines intersect at a slight angle, the gripping part to be used can be switched with only a slight change in the posture of the robot arm 9, and the time required to switch gripping parts can be reduced. Furthermore, since the robot hand 1 does not have a complex mechanism, the occurrence of malfunctions can be suppressed. In addition, since the robot hand 1 does not have a complex mechanism or drive source, its weight can be reduced compared to robot hands equipped with these.

[0015] Another feature of the robot hand 1 is that the first suction pad 15 and the second suction pad 16 are inclined such that their respective centerlines 15L and 16L move away from each other in a forward direction. This feature allows the height H1 in the vertical axis direction defined by the first suction pad 15 and the second suction pad 16 when the robot hand 1 according to this embodiment is inclined to be lower than the height H2 in the vertical axis direction defined by the first suction pad 15 and the second suction pad 16' when the robot hand in which the first suction pad 15 and the second suction pad 16 are inclined, with their respective centerlines 15L and 16L positioned parallel to the centerline 10L of the base plate 10 is inclined. As a result, as shown in Figure 5, when the robot hand 1 is inclined to grip the first workpiece 100 with the first suction pad 15, the possibility of the second suction pad 16 interfering with the container 300 can be reduced.

[0016] Furthermore, the inclination angles θ1 and θ2 of the centerlines 15L and 16L of the first suction pad 15 and the second suction pad 16, respectively, with respect to the centerline 10L of the base plate 10 are greater than 0 degrees and less than 45 degrees, respectively. In other words, the centerlines 15L and 16L intersect at an angle greater than 0 degrees and less than 90 degrees. As a result, as shown in Figure 6, when the robot hand 1 equipped on the wrist portion 91 of the robot arm 9 is rotated together with the wrist portion 91, the range of motion of the wrist portion 91 can be narrowed so that the robot hand 1 and the workpiece held by the robot hand 1 do not interfere with the robot arm 9. In other words, the range of motion of the wrist portion 91 can be widened, allowing the posture of the robot hand 1 to be changed more flexibly. When the robot hand 1 is actually used, the inclination angles θ1 and θ2 of the first and second suction pads 15 and 16 are designed to be in the range of greater than 5 degrees and less than 10 degrees, typically 7.5 degrees, taking into consideration the inclination angle of the workpiece in the container 300. In other words, the first and second suction pads 15 and 16 are designed such that the intersection angle of their respective centerlines 15L and 16L is in the range of more than 10 degrees to less than 20 degrees, typically 15 degrees.

[0017] The feature described in this embodiment, in which the first suction pad 15 and the second suction pad 16 are inclined such that their respective centerlines 15L and 16L are inclined toward each other toward forward, defines only the positional relationship between the first suction pad 15 and the second suction pad 16. Therefore, the robot hand 1 does not need to have both the first suction pad 15 and the second suction pad 16 inclined outward with respect to the centerline 10L of the base plate 10.

[0018] Hereinafter, with reference to Figure 7, a robot hand 2 according to the first modified example of this embodiment will be described. As shown in Figure 7, the first suction pad 15 may be fixed to the base plate 10 via the first support base 23 such that its centerline 15L is inclined outward at an angle θ3 with respect to the centerline 10L of the base plate 10, and the second suction pad 16 may be fixed to the base plate 10 via the second support base 24 such that its centerline 16L is parallel to the centerline 10L of the base plate 10. Even a robot hand 2 according to the first modified example configured in this way will have the same effects as that of this embodiment.

[0019] As shown in Figure 3, in the robot hand 1 according to this embodiment, the first support base 13 is tilted outward at an angle θ1 together with the first suction pad 15, and the second support base 14 is tilted outward at an angle θ2 together with the second suction pad 16. However, the shapes of the first and second support bases 13 and 14 are not limited to this embodiment, as long as the first and second suction pads 15 and 16 can be arranged in the positional relationship shown in Figure 3.

[0020] Hereinafter, a robot hand 3 according to a second modification of this embodiment will be described with reference to Figure 8. As shown in Figure 8, the robot hand 3 may be configured such that only the first suction pad 15 has its centerline 15L inclined outward at an angle θ1 with respect to the centerline 10L of the base plate 10, and the first support base 33 that supports the first suction pad 15 against the base plate 10 has its centerline 33L parallel to the centerline 10L of the base plate 10. In this case, the first support base 33 only needs to have a fixing surface to which the first suction pad 15 is fixed inclined outward at an angle θ1 with respect to the horizontal plane. Similarly, the second support base 34 may be configured such that its centerline 34L is parallel to the centerline of the base plate 10, and the fixing surface to which the second suction pad 16 is fixed inclined outward at an angle θ2 with respect to the horizontal plane. Even a robot hand 3 according to this second modification will have the same effects as that of this embodiment.

[0021] The robot hand 1 according to this embodiment has two types of gripping parts: a first suction pad 15 having a single suction hole and a second suction pad 16 having multiple suction holes. However, the gripping parts are not limited to suction pads. A third modified robot hand 4 according to this embodiment will be described below with reference to Figure 9. As shown in Figure 9, the robot hand 4 has a plurality of gripping parts, in this case two types: suction pads 15 and a gripper 46. The suction pad 15 is supported on the base plate 10 via a first support base 13 such that its centerline 15L is inclined outward at an inclination angle θ4 with respect to the centerline 10L of the base plate 10. The gripper 46 has a chuck mechanism 461 and a pair of finger parts 462, 463 connected to a pair of movable parts of the chuck mechanism 461. The gripper 46 is supported on the base plate 10 via a second support base 44 such that its centerline 46L is inclined outward at an inclination angle θ5 with respect to the centerline 10L of the base plate 10. The center line 46L of the gripper 46 can be defined as the axis of symmetry when the pair of finger portions 462 and 463 operate symmetrically. Alternatively, the center line 46L of the gripper 46 may be defined as a straight line perpendicular to the support surface of the second support base 44 to which the chuck mechanism 461 is attached, and passing through the gripping center position 46C of the gripper 46. Even a robot hand 4 according to this third modified example will have the same effects as that of this embodiment.

[0022] The robot hand according to this embodiment and its modified form has two types of gripping parts. However, the robot hand may have three or more types of gripping parts. For example, if there are three types of gripping parts, the three types of gripping parts may be fixed side by side, with the two types of gripping parts located at both ends fixed to the base plate 10 such that their respective centerlines are inclined outward with respect to the centerline 10L of the base plate 10, and the gripping part located in the center fixed to the base plate 10 such that its centerline is parallel to the centerline 10L of the base plate 10. Of course, the three types of gripping parts may also be arranged radially at equal intervals, and the three types of gripping parts may be fixed to the base plate 10 such that their respective centerlines are inclined outward with respect to the centerline 10L of the base plate 10.

[0023] The following additional notes are disclosed regarding this embodiment and its variations. (Note 1) The robot hand 1 has a base portion 10 attached to the tip of a robot arm 9 and a plurality of gripping portions 15, 16 supported by the base portion 10, the gripping portions 15, 16 being fixed to the base portion 10 and their respective centerlines inclined toward each other toward forward. (Note 2) In the robot hand 1 described in Note 1, the centerlines of the gripping portions 15, 16 are fixed to the base portion 10 such that they intersect at an angle of more than 0 degrees to less than 90 degrees. (Note 3) In the robot hand 1 described in Note 1, there are two gripping portions 15, 16, which are arranged symmetrically with respect to the centerline of the base portion 10. (Note 4) In the robot hand 1 described in Note 1, there are two gripping portions 15, 16, which have their respective centerlines inclined toward the centerline of the base portion 10 at an angle of inclination of more than 0 degrees to less than 45 degrees toward the centerline of the base portion 10. (Note 5) In the robot hand 1 described in Note 1, there are two gripping parts 15 and 16, one of which has its centerline inclined outward with respect to the centerline of the base part 10 at an angle of inclination of more than 0 degrees to less than 45 degrees, and the other gripping part 15 or 16 has its centerline parallel to the centerline of the base part 10. (Note 6) In the robot hand 1 described in Note 4, the angle of inclination of one of the centerlines of the gripping parts 15 or 16 with respect to the centerline of the base part 10 is the same as the angle of inclination of the other centerline of the gripping part 15 or 16 with respect to the centerline of the base part 10. (Note 7) In the robot hand 1 described in Note 4, the angle of inclination of one of the centerlines of the gripping parts 15 or 16 with respect to the centerline of the base part 10 is different from the angle of inclination of the other centerline of the gripping part 15 or 16 with respect to the centerline of the base part 10.

[0024] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0025] 1...Robot hand, 9...Robot arm, 91...Wrist section, 10...Base plate, 11...Adapter plate, 13, 14...Support base, 15, 16...Suction pads.

Claims

1. A robot hand having a base portion attached to the tip of a robot arm, and a plurality of gripping portions supported by the base portion, wherein the gripping portions are fixed to the base portion and their respective centerlines are inclined in a direction that moves away from each other toward the front.

2. The robot hand according to claim 1, wherein the centerlines of the gripping portions intersect at an angle greater than 0 degrees and less than 90 degrees.

3. The robot hand according to claim 1, wherein the gripping portion comprises two portions, which are arranged symmetrically with respect to the center line of the base portion.

4. The robot hand according to claim 1, wherein the gripping portion comprises two parts, and the centerlines of each part are inclined outward with respect to the centerline of the base portion at an angle of inclination of more than 0 degrees to less than 45 degrees.

5. The robot hand according to claim 1, wherein the gripping portion comprises two parts, one of which has its centerline inclined outward with respect to the centerline of the base portion at an angle of inclination of more than 0 degrees to less than 45 degrees, and the other having its centerline parallel to the centerline of the base portion.

6. The robot hand according to claim 4, wherein the angle of inclination of one center line of the gripping portion with respect to the center line of the base portion is the same as the angle of inclination of the other center line of the gripping portion with respect to the center line of the base portion.

7. The robot hand according to claim 4, wherein the angle of inclination of one center line of the gripping portion with respect to the center line of the base portion is different from the angle of inclination of the other center line of the gripping portion with respect to the center line of the base portion.

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