Transport robot hand and its control method

Abstract

The present invention provides a transport robot hand with a simple structure that allows the suction unit body to be tilted along the surface of a bag-shaped workpiece. [Solution] When the robot arm is brought close to the bag-shaped workpiece W, the movable connecting structures 25A to 25C, which are in an unlocked state, deform naturally, causing the suction unit body 3A to conform to the bag-shaped workpiece. After the suction unit body 3A conforms to the bag-shaped workpiece, the suction unit body 3A holds the bag-shaped workpiece in place, and then the cylinder rod 7A of the air cylinder 7 is retracted to lock the movable connecting structures 25A to 25C, thereby raising the robot arm.

Description

Technical Field

[0001] The present invention relates to a transport robot hand provided with, at the distal end of a robot arm, a suction part that sucks a bag-shaped workpiece, and a posture changing mechanism that changes the suction posture of the suction part relative to the bag-shaped workpiece, and a control method thereof.

Background Art

[0002] Japanese Patent No. 7560110 (Patent Document 1) discloses a transport robot hand provided with a posture changing mechanism that changes the suction posture of a suction part relative to a bag-shaped workpiece. This transport robot hand is provided with a tilting mechanism that supports the suction part in a tiltable manner, a slide mechanism that supports the suction part such that the tilting fulcrum of the suction part is slidable in a sliding direction intersecting the elevating direction relative to a main body supported by a moving mechanism, and a switching mechanism that switches between a locked state in which sliding of the tilting fulcrum from the reference position by the slide mechanism is not permitted, and an unlocked state in which sliding of the tilting fulcrum by the slide mechanism is permitted without application of an elastic biasing force of a magnitude that can return the tilting fulcrum to the reference position. This switching mechanism returns the tilting fulcrum to the reference position when switching from the unlocked state to the locked state. With such a structure, suction is performed with the suction part placed in a state of being along the bag-shaped workpiece, and thereafter the bag-shaped workpiece is transported in a horizontal state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

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

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

[0006] Another object of the present invention is to provide a control method for a conveying robot hand that allows the suction unit body to be tilted along the surface of a bag-shaped workpiece with simple control. [Means for solving the problem]

[0007] The present invention relates to a transport robot hand equipped with a suction unit for adsorbing a bag-shaped workpiece and a posture changing mechanism for changing the suction position of the suction unit on the bag-shaped workpiece, at the tip of the robot arm. The posture changing mechanism of the transport robot hand of the present invention comprises an air cylinder, one end of which is connected to the suction unit body of the suction unit via a universal joint and the other end of which is connected to a support structure provided at the tip of the robot arm via a universal joint; two or more linear guides arranged around the air cylinder, spaced radially apart from the air cylinder and spaced circumferentially around the air cylinder, and not facing each other radially; and two or more movable connecting structures, each 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 that can move along a corresponding linear guide, a connecting member whose one end is rotatably and swingably connected to the movable member by a first joint and whose other end is rotatably and swingably connected to the suction unit body by a second joint, and a stopper that contacts the movable member and restricts its upward movement. The two or more second joints of the two or more movable connecting structures are attached to the suction unit body with circumferential spacing between them and so as not to face each other radially. When the movable member is in contact with the stopper, the two or more movable connecting structures are locked, and when the movable member moves away from the stopper, the two or more movable connecting structures become unlocked and the air cylinder no shi The Linda rod is designed to allow vertical movement and rotational motion at its tip.

[0008] According to the present invention, when picking up a bag-shaped workpiece, simply bringing the robot arm close to the bag-shaped workpiece allows the unlocked movable coupling structure to naturally deform, bringing the suction unit body to conform to the bag-shaped workpiece without any special control. After the suction unit body conforms to the bag-shaped workpiece, and after the bag-shaped workpiece is picked up by the suction unit body, the cylinder rod of the air cylinder is retracted to lock two or more movable coupling structures, and when the robot arm is pulled up, the bag-shaped workpiece can be transported in a horizontal position. Thus, with the transport robot of the present invention, the suction unit body can be tilted to conform to the surface of the bag-shaped workpiece with a simple structure without requiring complex control, and even after picking up, the posture of the suction unit body can be easily returned to a horizontal position for transport.

[0009] The first joint may consist of a shaft portion supported by a movable member and extending horizontally, and a rod end having a self-aligning sliding bearing attached to the shaft portion. The second joint may also consist of a shaft portion supported by the suction body and extending parallel to the suction body, and a rod end having a self-aligning sliding bearing attached to the shaft portion. By adopting such a configuration, a movable connecting structure can be constructed inexpensively using commercially available rod ends.

[0010] In the control method for a transport robot hand of the present invention, first, in the first step, two or more movable coupling structures are unlocked, and the tip of the robot arm is lowered so that the suction surface of the suction unit body is brought close to the bag-shaped workpiece. Next, in the second step, during or after the execution of the first step, the cylinder rod of the air cylinder is extended, or the tip of the robot arm is lowered further to press the suction surface of the suction unit body against the bag-shaped workpiece. Next, in the third step, the bag-shaped workpiece is picked up by the suction unit. Then, in the fourth step, after the completion of the third step, the cylinder rod of the air cylinder is retracted and the air cylinder is driven until two or more movable coupling structures are locked. Finally, in the fifth step, after the completion of the third step, during or after the execution of 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, by simply controlling the movement of the robot arm, the air cylinder, the drive control, and the suction part, the suction part can be aligned with the slanted bag-shaped workpiece, and the bag-shaped workpiece can be easily transported by suction. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of the transport robot hand of this embodiment. [Figure 2] This is an exploded perspective view used to explain the mounting structure of the air cylinder that serves as the drive source for the attitude change mechanism. [Figure 3] This is an exploded perspective view of the linear guide and movable coupling structure. [Figure 4] (A) through (C) are diagrams used to explain the adsorption operation. [Figure 5] (A) and (B) are diagrams used to explain the feasibility of the arrangement of the linear guide and the movable coupling structure. [Figure 6] This diagram shows a flowchart illustrating an example of a control method for a transport robot hand. [Modes for carrying out the invention]

[0012] An embodiment of the transport robot hand of the present invention will be described below with reference to the drawings. Figure 1 shows a perspective view of the transport robot hand 1 of this embodiment. Figure 2 is an exploded perspective view illustrating the mounting structure of the air cylinder 7, which is the drive source for the attitude 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 for adsorbing bag-shaped workpieces such as cement bags, and an attitude change mechanism 5 for changing the suction posture of the suction unit 3 on the bag-shaped workpiece. The suction unit 3 has a suction unit body 3A having a suction nozzle connected to a vacuum generator (not shown) via a connecting means, and an elastic skirt portion 3B provided at the lower part of the suction unit body 3A that deforms along the surface of the bag-shaped workpiece.

[0013] The posture change mechanism 5 is equipped with an air cylinder 7 as a drive source. One end of the cylinder rod 7A of the air cylinder 7 is connected to the suction part body 3A of the suction part 3 via a universal joint 9, and the other end of the cylinder body 7B is connected to the support structure 2 provided at the tip of the robot arm via a universal joint 11. As shown in Figure 2, a mounting fixture 13 equipped with a fixing plate 13b having a connecting pin 13a for connecting the universal joint 11 is fixed to the other end of the cylinder body 7B of the air cylinder 7. A mounting fixture 15 equipped with a fixing plate 15b having a connecting pin 15a for connecting the universal joint 11 is also fixed to the back surface of the support structure 2. The universal joint 11 connects these mounting fixtures 13 and 15. A mounting fixture 17 having an outer shape similar to a nut and equipped with 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, and a mounting fixture 19 equipped with a connecting pin (not shown) for connecting the universal joint 9 is also fixed to the suction part body 3A. Furthermore, a rotation-preventing guide 21 is fixed to one end of the air cylinder 7 to prevent the cylinder rod 7A from rotating. This rotation-preventing guide 21 comprises 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, one end of which is fixed to the movable plate 21B and which slide through the fixed plate 21C. Alternatively, an air cylinder with a rotation-preventing mechanism may be used instead of using such a rotation-preventing guide 21.

[0014] In this embodiment, the air cylinder 7 is surrounded by three linear guides 23A to 23C, which are spaced radially apart from the air cylinder 7 and circumferentially apart from the air cylinder 7, and are not radially opposite to each other. The air cylinder 7 is also surrounded by three movable connecting structures 25A to 25C, which are respectively positioned between the three linear guides 23A to 23C and the suction body 3A. Each of the three movable connecting structures 25A to 25C includes 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 whose one end is rotatably and swingably connected to the movable member 26a to 26c by a first joint 27a to 27c and whose other end is rotatably and swingably connected to the suction 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] Figure 3 shows exploded perspective views of the linear guide 23A and the movable connecting structure 25A, representing the three linear guides 23A to 23C and the three movable connecting structures 25A to 25C, respectively. The details of the linear guide 23A and the movable connecting structure 25A will be explained below using Figure 3, and the explanations of the linear guides 23B and 23C and the movable connecting structures 25B and 25C will be omitted. The linear guide 23A includes a guide plate GP and a guide rail L. The movable member 26a consists of 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 consists of a shaft portion SF1 that extends horizontally and is rotatably supported at both ends by a pair of bearings b on fixing devices F1 and F2 fixed to the movable member 26a, and a rod end RE1 having a self-aligning sliding bearing attached to the shaft portion SF1. The second joint 28a also consists of a shaft SF2 that extends parallel to the suction body 3A and is rotatably supported at both ends by bearings b attached to the suction body 3A by fixing devices F3 and F4, and a rod end RE2 having a self-aligning sliding bearing attached to the shaft SF2. This structure enables the first joints 27a to 27c and the second joints 28a to 28c to achieve rotatable and swingable connections, respectively.

[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 body 3A at equal intervals in the circumferential direction 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 configured such 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 move away 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 vertically and rotate.

[0017] Figure 4(A) shows an example of the state when a bag-shaped workpiece W is deformed and its surface is inclined, and the conveying robot hand 1 of this embodiment picks up and conveys the bag-shaped workpiece. As shown in order in Figures 4(A) to (C), according to this embodiment, when picking up a bag-shaped workpiece W, simply by bringing the robot arm close to the bag-shaped workpiece, the movable connecting structures 25A to 25C, which are in an unlocked state, deform naturally, and the suction part body 3A can be brought to conform to the bag-shaped workpiece W without any special control. Then, as shown in Figure 4(C), after the elastic skirt portion 3B below the suction unit body 3A is aligned with the bag-shaped workpiece W, the bag-shaped workpiece W is sucked up by the suction unit body 3A. By retracting the cylinder rod 7A of the air cylinder 7, the moving members 26a to 26c of the three movable connecting structures 25A to 25C are brought into contact with the stoppers 30a to 30c, locking the three movable connecting structures 25A to 25C. When the robot arm is pulled up, the bag-shaped workpiece W can be transported in a horizontal position. Thus, with the transport robot of the present invention, the suction unit body 3A can be tilted along the surface of the bag-shaped workpiece W with a simple structure without requiring complex control, and even after sucking, the posture of the suction unit body 3A can be easily returned to a horizontal position for transport.

[0018] Unlike the above embodiment, if the three linear guides 23A to 23C and the three movable connecting structures 25A to 25C are not spaced equally in the circumferential direction, and instead arranged circumferentially so that the two second joints 28a and 28b face each other radially as shown in Figure 5(A), then the movement of the three movable connecting structures 25A to 25C will prevent the suction unit body 3A from moving smoothly vertically or from rotating smoothly horizontally. Therefore, the three linear guides 23A to 23C and the three movable connecting structures 25A to 25C must be spaced radially between them and the air cylinder 7, spaced circumferentially around the air cylinder 7, and not facing each other radially. As long as this principle is followed, theoretically, two or more linear guides and movable connecting structures can be provided. For example, when using two linear guides 23A and 23B and two movable connecting structures 25A and 25B, the two linear guides 23A and 23B must not be configured to face each other with the air cylinder 7 in between, as shown in Figure 5(A), but rather, as shown in Figure 5(B), the two linear guides 23A and 23B must not be configured to face each other with the air cylinder 7 in between.

[0019] Figure 6 shows a flowchart of an example of the control method for the aforementioned transfer robot hand 1. This control method can be executed using a computer implemented in a control device of a transfer robot (not shown). In the first step ST1, two or more movable connection structures are set to an unlocked state, and the distal end portion of the robot arm is lowered so as to bring the suction surface of the suction part main body 3A close to a position proximate to the bag-shaped workpiece W. Next, in the second step ST2, during execution of the first step ST1 or after the end of the first step ST1, the cylinder rod 7A of the air cylinder 7 is extended, or the distal end portion of the robot arm is further lowered to press the suction surface of the suction part main body 3A against the bag-shaped workpiece W. The execution of step ST2 may allow the cylinder rod 7A to freely descend by its own weight to press the suction surface of the suction part main body 3A against the workpiece W, or the air cylinder 7 may actively lower the cylinder rod 7A to press the suction surface of the suction part main body 3A against the bag-shaped workpiece W, or the robot arm may be lowered to press the suction surface of the suction part 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 part 3. Thereafter, in the fourth step ST4, after the third step ST3 is completed, the cylinder rod 7A of the air cylinder 7 is retracted to drive the air cylinder 7 until the two or more movable connection structures enter a locked state. The timing for driving the air cylinder 7 in the fourth step is not limited to immediately after suction, and may be performed while the robot arm is being raised, or after the robot arm has been raised. Then, in the fifth step ST5, after the third step is completed, during execution of the fourth step ST4 or after the end of the fourth step ST4, the distal end of the robot arm is raised and moved to a predetermined position.

[0021] According to such a control method, the suction part 3 can be made to follow the inclined bag-shaped workpiece W and the bag-shaped workpiece can be easily sucked and transferred only by the movement of the robot arm, the drive control of the air cylinder 7, and the control of the suction part 3. [Industrial Applicability]

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

[0023] 1…Robot hand for transport 2...Support structure part 3...Adsorption part 3A... Adsorption unit body 3B...Elastic skirt section 5. Posture change mechanism 7... Air cylinder 7A...Cylinder rod 7B...Cylinder body 9... Flexible joint 11... Universal joint 21... Anti-rotation 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 comprising a suction unit for adsorbing a bag-shaped workpiece and a posture changing mechanism for changing the suction position of the suction unit relative to the bag-shaped workpiece, wherein the tip of the robot arm is equipped with a suction unit for adsorbing a bag-shaped workpiece, The aforementioned attitude changing mechanism is An air cylinder having one end connected to the suction part body of the suction part 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 guides are arranged around the air cylinder, spaced radially apart from the air cylinder and spaced circumferentially around the air cylinder, and not facing each other in the radial direction. The system comprises two or more movable connecting structures, each positioned between the two or more linear guides and the suction unit body, Each of the two or more movable connecting structures comprises a movable member that can move along the corresponding linear guide, a connecting member whose one end is rotatably and swingably connected to the movable member by a first joint and whose other end is rotatably and swingably connected to the suction body by a second joint, and a stopper that contacts the movable member to restrict the 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 body with a gap 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 combined in such a way that when the moving member is in contact with the stopper, the two or more movable connecting structures are locked, and when the moving member moves away from the stopper, the two or more movable connecting structures are unlocked, allowing vertical movement and rotational movement of the tip of the cylinder rod of the air cylinder.

2. The first joint consists of a shaft portion supported by the moving member and extending horizontally, and a rod end having a self-aligning sliding bearing attached to the shaft portion. The transport robot hand according to claim 1, wherein the second joint comprises a shaft portion supported by the suction body and extending parallel to the suction body, and a rod end having a self-aligning sliding bearing attached to the shaft portion.

3. A method for controlling a transport robot hand according to claims 1 to 2, The first step involves disengaging the two or more movable connecting structures and lowering the tip of the robot arm so that the suction surface of the suction unit body is brought close to the bag-shaped workpiece. A second step is to extend the rod of the air cylinder or to further lower the tip of the robot arm so that the suction surface of the suction unit body is pressed against the bag-shaped workpiece, during or after the execution of the first step. A third step involves adsorbing the bag-shaped workpiece with the adsorption part, A fourth step is to retract the rod of the air cylinder after the third step is completed and drive the air cylinder until the two or more movable coupling structures are locked, A method for controlling a transport robot hand, characterized in that, after the third step is completed, a fifth step is performed in which the tip of the robot arm is raised and moved to a predetermined position during or after the execution of the fourth step.

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