Transport robot hand and control method thereof

Abstract

To provide a transport robot hand with a simple structure, capable of tilting an adsorption part body along the surface of a bag-like workpiece. [Solution] When adsorbing a bag-shaped workpiece W, as the robot arm approaches the bag-shaped workpiece, the movable connecting structures 25A to 25C, which are in an unlocked state, naturally deform, causing the suction unit main body 3A to align with the bag-shaped workpiece. After the suction unit main body 3A has been brought into alignment with the bag-shaped workpiece and the bag-shaped workpiece has been adsorbed by the suction unit main body 3A, the cylinder rod 7A of the air cylinder 7 is contracted, thereby locking the movable connecting structures 25A to 25C, and the robot arm is then lifted up.

Description

[Technical Field]

[0001] The present invention relates to a transport robot hand equipped with a suction section at the tip of a robot arm that suctions bag-shaped workpieces and a posture change mechanism that changes the suction posture of the suction section relative to the bag-shaped workpieces, and a control method for the same. [Background technology]

[0002] Japanese Patent Publication No. 7560110 (Patent Document 1) discloses a transport robot hand equipped with a posture change mechanism that changes the suction posture of the suction part relative to a bag-shaped workpiece. This transport robot hand includes a tilting mechanism that tiltably supports the suction part, a sliding mechanism that supports the suction part so that the tilting fulcrum of the suction part can slide relative to a main body supported by a moving mechanism in a sliding direction that intersects the lifting direction, and a switching mechanism that switches between a locked state, which does not allow the sliding of the tilting fulcrum from its reference position by the sliding mechanism, and an unlocked state, which allows the sliding of the tilting fulcrum by the sliding mechanism without applying an elastic biasing force large enough to return it to the reference position. When switching from the unlocked state to the locked state, the switching mechanism returns the tilting fulcrum to its reference position. With this structure, the suction part is placed against the bag-shaped workpiece to perform suction, and the bag-shaped workpiece is then placed in a horizontal position for transport. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7560110 Summary of the Invention [Problem to be solved by the invention]

[0004] The transport robot hand disclosed in Patent Document 1 has a problem in that the structure of the posture changing mechanism is complicated, and the control is also inevitably complicated.

[0005] An object of the present invention is to provide a transport robot hand with a simple structure that can tilt the suction portion body along the surface of a bag-shaped workpiece.

[0006] Another object of the present invention is to provide a method for controlling a transport robot hand that can tilt the suction portion main body along the surface of a bag-like workpiece with simple control. [Means for solving the problem]

[0007] The present invention relates to a transport robot hand equipped with a suction unit at the tip of a robot arm for suctioning bag-shaped workpieces, and a posture change mechanism for changing the suction posture of the suction unit relative to the bag-shaped workpieces. The posture change mechanism for the transport robot hand of the present invention includes an air cylinder having one end connected to the suction unit body of the suction unit via a universal joint and the other end connected via a universal joint to a support structure provided at the tip of the robot arm, two or more linear guides arranged around the air cylinder at a radial distance from the air cylinder, a circumferential distance from the air cylinder, and not radially facing each other, and two or more movable connecting structures respectively arranged between the two or more linear guides and the suction unit body. Each of the two or more movable connecting structures includes a movable member movable along a corresponding linear guide, a connecting member having one end rotatably and swingably connected to the movable member by a first joint and the other end rotatably and swingably connected to the suction unit main body by a second joint, and a stopper that abuts against the movable member to restrict upward movement of the movable member, and the two or more second joints of the two or more movable connecting structures are attached to the suction unit main body at intervals in the circumferential direction and so as not to face each other in the radial direction. The two or more linear guides and the two or more movable connecting structures are locked when the movable member abuts against the stopper, and are unlocked when the movable member moves away from the stopper, thereby moving the air cylinder. Noshi The cylinder rod is combined to allow the tip of the cylinder rod to move up and down and to pivot.

[0008] According to the present invention, when adsorbing a bag-shaped workpiece, the robot arm is simply brought close to the bag-shaped workpiece, and the movable connecting structures, which are in an unlocked state, naturally deform, allowing the suction unit main body to align with the bag-shaped workpiece, without any special control. After the suction unit main body is aligned with the bag-shaped workpiece, the suction unit main body adsorbs the bag-shaped workpiece, and then the cylinder rod of the air cylinder is contracted to lock the two or more movable connecting structures, and the robot arm is raised, allowing the bag-shaped workpiece to be transported in a horizontal position. Thus, according to the transport robot of the present invention, the suction unit main body can be tilted to align with the surface of the bag-shaped workpiece with a simple structure, without requiring complex control, and the suction unit main body can be easily kept horizontal after adsorption.

[0009] The first joint may be composed of a shaft supported by the moving member and extending horizontally, and a rod end having an aligning plain bearing attached to the shaft, and the second joint may be composed of a shaft supported by the suction unit main body and extending parallel to the suction unit main body, and a rod end having an aligning plain bearing attached to the shaft. By adopting such a configuration, a movable connecting structure can be constructed inexpensively using a ready-made rod end.

[0010] In the control method for a transport robot hand of the present invention, in a first step, two or more movable connecting structures are unlocked and the tip of the robot arm is lowered so that the suction surface of the suction unit main body approaches a position close to the bag-shaped workpiece. Next, in a second step, during or after the first step, the cylinder rod of the air cylinder is extended or the tip of the robot arm is further lowered to press the suction surface of the suction unit main body against the bag-shaped workpiece. Next, in a third step, the suction unit adsorbs the bag-shaped workpiece. Then, in a fourth step, after the third step is completed, the cylinder rod of the air cylinder is retracted to drive the air cylinder until the two or more movable connecting structures are locked. Finally, in a fifth step, after the third step is completed, during or after the fourth step, the tip of the robot arm is raised and moved to a predetermined position. Thus, according to the control method for the transport robot hand of the present invention, the suction part can be aligned with the slanted bag-shaped workpiece by simply moving the robot arm, controlling the drive of the air cylinder, and controlling the suction part, and the bag-shaped workpiece can be easily sucked and transported. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a transport robot hand according to the present embodiment. [Figure 2] FIG. 10 is an exploded perspective view used to explain the mounting structure of an air cylinder that serves as a drive source for the attitude change mechanism. [Figure 3] FIG. 2 is an exploded perspective view of a linear guide and a movable connecting structure. [Figure 4] 10A to 10C are diagrams used to explain the adsorption operation. [Figure 5] 10A and 10B are diagrams used to explain whether or not the arrangement of the linear guide and the movable connecting structure is possible. [Figure 6] FIG. 10 is a flowchart illustrating an example of a control method for a transport robot hand. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the transport robot hand of the present invention will be described below with reference to the drawings. FIG. 1 shows a perspective view of the transport robot hand 1 of this embodiment. FIG. 2 is an exploded perspective view illustrating the mounting structure of an air cylinder 7, which serves as the drive source for the position change mechanism 5 (described later). The transport robot hand 1 of this embodiment is mounted below a support structure 2 attached to the tip of a robot arm (not shown). The transport robot hand 1 includes a suction unit 3 that suctions a bag-shaped workpiece such as a cement bag, and a position change mechanism 5 that changes the suction position of the suction unit 3 relative to the bag-shaped workpiece. The suction unit 3 includes a suction unit main body 3A with a suction nozzle connected to a vacuum generator (not shown) via a connection means, and an elastic skirt portion 3B attached to the bottom of the suction unit main body 3A that deforms along the surface of the bag-shaped workpiece.

[0013] The posture change mechanism 5 includes an air cylinder 7 as a drive source. One end of a cylinder rod 7A of the air cylinder 7 is connected to the suction unit body 3A of the suction unit 3 via a universal joint 9, and the other end of the cylinder body 7B is connected to a support structure 2 provided at the tip of the robot arm via a universal joint 11. As shown in FIG. 2, a fixture 13 is fixed to the other end of the cylinder body 7B of the air cylinder 7. The fixture 13 includes a fixing plate 13b having a connecting pin 13a for connecting the universal joint 11. A fixture 15 is also fixed to the back surface of the support structure 2. The fixture 15 includes a fixing plate 15b having a connecting pin 15a for connecting the universal joint 11. The universal joint 11 connects these fixtures 13 and 15. A fixture 17 having an outer shape similar to a nut and including a connecting pin (not shown) for connecting the universal joint 9 is also fixed to the tip of the cylinder rod 7A of the air cylinder 7. A fixture 19 having a connecting pin (not shown) for connecting the universal joint 9 is also fixed to the suction unit body 3A. Furthermore, a detent guide 21 that prevents the cylinder rod 7A from rotating is fixed to one end of the air cylinder 7. This detent guide 21 includes a movable plate 21B with a recess 21A that fits into the hexagonal outer surface of the mounting fixture 17, a fixed plate 21C fixed to the cylinder body, and two rods 21D that have one end fixed to the movable plate 21B and slidably pass through the fixed plate 21C. Note that an air cylinder with a detent may be used instead of using such a detent guide 21.

[0014] In this embodiment, there are provided three linear guides 23A to 23C arranged around the air cylinder 7 with a radial gap between them and the air cylinder 7, with a circumferential gap between them and the air cylinder 7, and so as not to face each other radially, and three movable connecting structures 25A to 25C arranged between the three linear guides 23A to 23C and the suction portion main body 3A, respectively. The three movable connecting structures 25A to 25C each include a movable member 26a to 26c that can move along the corresponding linear guide 23A to 23C, a rod-shaped connecting member 29a to 29c that has one end rotatably and swingably connected to the movable member 26a to 26c by a first joint 27a to 27c and the other end rotatably and swingably connected to the suction part main body 3A by a second joint 28a to 28c, and a stopper 30a to 30c that abuts against the movable member 26a to 26c and restricts the upward movement of the movable member 26a to 26c.

[0015] FIG. 3 shows an exploded perspective view of the linear guide 23A and the movable connecting structure 25A, respectively representing the three linear guides 23A-23C and the three movable connecting structures 25A-25C. Hereinafter, the linear guide 23A and the movable connecting structure 25A will be described in detail using FIG. 3, and the linear guides 23B and 23C and the movable connecting structures 25B and 25C will not be described. The linear guide 23A includes a guide plate GP and a guide rail L. The moving member 26a includes a slider S that slides along the guide rail L and a slide plate SP fixed to the slider S. Fixing devices F1 and F2 are fixed to the slide plate SP. The first joint 27a includes a horizontally extending shaft SF1 whose both ends are rotatably supported by fixing devices F1 and F2 fixed to the moving member 26a using a pair of bearings b, and a rod end RE1 having an aligning plain bearing attached to the shaft SF1. The second joint 28a is also composed of a shaft SF2 extending parallel to the suction unit main body 3A and having both ends rotatably supported by bearings b attached to the suction unit main body 3A by fixtures F3 and F4, and a rod end RE2 having an aligning plain bearing attached to the shaft SF2. With this structure, the first joints 27a to 27c and the second joints 28a to 28c are each connected in a manner that allows them to rotate and swing.

[0016] In this embodiment, the three second joints 28a to 28c of the three movable connecting structures 25A to 25C are attached to the suction unit main body 3A at equal circumferential intervals and so as not to face each other in the radial direction. The three linear guides 23A to 23C and the three movable connecting structures 25A to 25C are combined so that when the moving members 26a to 26c are in contact with the stoppers 30a to 30c, the three movable connecting structures 25A to 25C are locked, and when the moving members 26a to 26c are separated from the stoppers 30a to 30c, the three movable connecting structures 25A to 25C are unlocked, allowing the tip of the cylinder rod 7A of the air cylinder 7 to move up and down and pivot.

[0017] 4(A) shows an example of a state in which a bag-shaped workpiece W is adsorbed and transported by the transport robot hand 1 of this embodiment when the bag-shaped workpiece W is deformed and its surface is inclined. As shown in order in FIGS. 4(A) to 4(C), according to this embodiment, when adsorbing the bag-shaped workpiece W, the movable connecting structures 25A to 25C in the unlocked state are naturally deformed without any special control, and the adsorption portion main body 3A can be fitted to the bag-shaped workpiece W simply by bringing the robot arm close to the bag-shaped workpiece W. 4(C), after the elastic skirt portion 3B below the suction portion main body 3A is fitted to the bag-shaped workpiece W, the suction portion main body 3A adsorbs the bag-shaped workpiece W, and then the cylinder rod 7A of the air cylinder 7 is contracted to bring the moving members 26a to 26c of the three movable connecting structures 25A to 25C into contact with the stoppers 30a to 30c, locking the three movable connecting structures 25A to 25C, and then the robot arm is raised, allowing the bag-shaped workpiece W to be transported in a horizontal position. Thus, the transport robot of the present invention can tilt the suction portion main body 3A along the surface of the bag-shaped workpiece W with a simple structure without requiring complex control, and can easily transport the suction portion main body 3A in a horizontal position after adsorption.

[0018] Unlike the above embodiment, if the three linear guides 23A-23C and the three movable connecting structures 25A-25C were arranged circumferentially without being equally spaced circumferentially, as shown in FIG. 5A, with the two second joints 28a and 28b facing each other in the radial direction, the three movable connecting structures 25A-25C would not be able to smoothly move the suction unit main body 3A up and down or smoothly rotate the suction unit main body 3A in the horizontal direction. Therefore, the three linear guides 23A-23C and the three movable connecting structures 25A-25C must be arranged around the air cylinder 7 with a radial gap between them, a circumferential gap around the air cylinder 7, and no radial gap between them. As long as this principle is observed, theoretically, two or more linear guides and two or more movable connecting structures can be provided. For example, when two linear guides 23A and 23B and two movable connecting structures 25A and 25B are used, the two linear guides 23A and 23B should not be configured to face each other with the air cylinder 7 sandwiched between them, as shown in Figure 5(A), but should be configured so that the two linear guides 23A and 23B do not face each other with the air cylinder 7 sandwiched between them, as shown in Figure 5(B).

[0019] FIG. 6 shows a flowchart of an example of a control method for the transport robot hand 1. This control method can be executed using a computer implemented in the control device of the transport robot (not shown). In a first step ST1, two or more movable connecting structures are unlocked, and the tip of the robot arm is lowered so that the suction surface of the suction unit main body 3A approaches a position close to the bag-shaped workpiece W. Next, in a second step ST2, during or after the execution of the first step ST1, the cylinder rod 7A of the air cylinder 7 is extended, or the tip of the robot arm is further lowered, so that the suction surface of the suction unit main body 3A is pressed against the bag-shaped workpiece W. Step ST2 may be executed by lowering the cylinder rod 7A automatically under its own weight to press the suction surface of the suction unit main body 3A against the workpiece W, or by actively lowering the cylinder rod 7A using the air cylinder 7 to press the suction surface of the suction unit main body 3A against the bag-shaped workpiece W, or by lowering the robot arm to press the suction surface of the suction unit main body 3A against the bag-shaped workpiece W.

[0020] Next, in the third step ST3, the bag-shaped workpiece is sucked by the suction unit 3. Then, in the fourth step ST4, after the third step ST3 is completed, the cylinder rod 7A of the air cylinder 7 is retracted and the air cylinder 7 is driven until two or more movable connecting structures are locked. Note that the timing for driving the air cylinder 7 in the fourth step can be other than immediately after suction, and can be while the robot arm is rising or after it has been raised. Then, in the fifth step ST5, after the third step is completed, the tip of the robot arm is raised and moved to a predetermined position during or after the execution of the fourth step ST4.

[0021] According to this control method, by simply moving the robot arm, controlling the drive of the air cylinder 7, and controlling the suction part 3, the suction part 3 can be aligned with the slanted bag-shaped workpiece W, and the bag-shaped workpiece can be easily sucked and transported. [Industrial Applicability]

[0022] According to the present invention, the suction unit body can be tilted along the surface of the bag-shaped workpiece with a simple structure without requiring complex control, and even after suction, the suction unit body can be easily placed in a horizontal position for transport. [Explanation of symbols]

[0023] 1...Transport robot hand 2...Support structure part 3...Adsorption part 3A...Adsorption unit body 3B...Elastic skirt part 5...Attitude change mechanism 7...Air cylinder 7A...Cylinder rod 7B...Cylinder body 9...Universal joint 11...Universal joint 21...Non-rotating guide 23A to 23C... Linear guide 25A to 25C…Movable connection structure 26a to 26c...moving members 27a to 27c...First joint 28a to 28c...Second joint 29a to 29c...Connecting members 30a to 30c...Stopper

Claims

1. A transport robot hand provided at a tip of a robot arm with a suction unit that suctions a bag-shaped workpiece and a posture change mechanism that changes the suction posture of the suction unit relative to the bag-shaped workpiece, The attitude change mechanism includes: an air cylinder having one end connected to a suction portion main body of the suction portion via a universal joint and the other end connected to a support structure provided at the tip of the robot arm via a universal joint; two or more linear motion guides arranged around the air cylinder with a radial gap between them and the air cylinder, with a gap in the circumferential direction of the air cylinder, and not facing each other in the radial direction; two or more movable connecting structures respectively disposed between the two or more linear guides and the suction portion main body; Each of the two or more movable connecting structures includes a moving member that is movable along the corresponding linear motion guide, a connecting member that has one end rotatably and swingably connected to the moving member by a first joint and the other end rotatably and swingably connected to the suction unit main body by a second joint, and a stopper that abuts against the moving member to restrict upward movement of the moving member, and the two or more second joints of the two or more movable connecting structures are attached to the suction unit main body at intervals in the circumferential direction and do not face each other in the radial direction, The two or more linear guides and the two or more movable connecting structures are combined so that when the movable member is in contact with the stopper, the two or more movable connecting structures are locked, and when the movable member is separated from the stopper, the two or more movable connecting structures are unlocked, allowing the tip of the cylinder rod of the air cylinder to move up and down and to rotate.

2. the first joint includes a shaft portion supported by the moving member and extending in a horizontal direction, and a rod end having an aligning plain bearing attached to the shaft portion, 2. The transport robot hand according to claim 1, wherein the second joint comprises a shaft supported by the suction unit body and extending parallel to the suction unit body, and a rod end having an aligning plain bearing attached to the shaft.

3. 3. A method for controlling a transport robot hand according to claim 1, comprising: a first step of lowering a tip end of the robot arm so that the suction surface of the suction unit main body approaches a position close to the bag-like workpiece while the two or more movable connecting structures are in an unlocked state; a second step of extending the rod of the air cylinder or further lowering the tip of the robot arm during execution of the first step or after completion of the first step to press the suction surface of the suction unit main body against the bag-shaped workpiece; a third step of suctioning the bag-shaped workpiece with the suction unit; a fourth step of retracting the rod of the air cylinder after the third step is completed, and driving the air cylinder until the two or more movable connecting structures are in a locked state; A method for controlling a transport robot hand, characterized in that after the third step is completed, a fifth step is carried out in which the tip of the robot arm is raised and moved to a predetermined position during or after the fourth step is completed.

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