Industrial robot and control method thereof

Abstract

To provide an industrial robot for transport in which even when transporting a work-piece that has a large size and a thin thickness, the work-piece is reliably held by a hand by suppressing the effects of wind pressure while preventing a tact time from becoming excessively long, and .SOLUTION: An industrial robot has a base, a hand, an arm to which the hand is connected, an arm support part for supporting the arm, and a lifting mechanism which lifts the arm support art with respect to the base, and the robot, on which a work-piece is mounted on the hand, operates on the basis of a specified value of an operational speed. The industrial robot executes, when an operation command given to the industrial robot includes lowering of the arm support part (Step 103: Yes), deceleration processing for changing a position of the hand on the basis of an operational speed smaller than the specified value to control drive of each shaft (Step 104).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an industrial robot that transports plate-like or sheet-like workpieces such as glass substrates used for liquid crystal display panels and organic EL (electroluminescence) panels, and a control method thereof. [Background technology]

[0002] For example, in a manufacturing line for liquid crystal display panels used in liquid crystal display devices, a robot is used to transport a plate-shaped workpiece such as a glass substrate between different processing devices. In this case, the workpiece is transported by inserting the hand of the transport robot into a cassette or load lock chamber of the processing device that is the source of the workpiece, holding the workpiece on the hand, pulling out the hand with the workpiece on it from the cassette, moving the arm of the robot or the entire robot with the workpiece on the hand, then inserting the hand into a cassette of the processing device that is the destination of the workpiece to store the workpiece in the cassette, and then pulling out only the hand from the cassette. In some cases, a suction device provided on the hand is used to suction the workpiece to the underside of the hand and transport the workpiece. The hand is, for example, fork-shaped. The transport robot includes, for example, a horizontal multi-joint mechanism formed by connecting two arms and equipped with a hand at the tip, a lifting mechanism for raising and lowering the hand together with the horizontal multi-joint mechanism in the vertical direction, and a rotation mechanism for rotating the entire horizontal multi-joint mechanism in a horizontal plane with a vertical axis as the rotation axis. The horizontal articulated mechanism can move the hand forward or backward on the same straight line by making the angle between its two arms smaller or larger. To change the direction in which the hand moves on the horizontal plane, the horizontal articulated mechanism must be rotated by a rotation mechanism. In addition, a transport mechanism is provided to move the entire robot in a straight line on the horizontal plane.

[0003] When transporting a workpiece, even if the robot is moving rapidly, the workpiece needs to be accurately positioned relative to the hand and securely held by the hand. Patent Document 1 discloses a technique for preventing a large workpiece with a large amount of deflection from being misaligned on the hand, in which the hand is provided with multiple rubber or resin pads having contact surfaces that come into contact with the underside of the workpiece, and the contact surfaces of the pads are spherical. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-217509 A Summary of the Invention [Problem to be solved by the invention]

[0005] As workpieces become larger and thinner, the effect of wind pressure on the workpieces during their transportation by a robot cannot be ignored. In the case of a robot that transports a workpiece by holding it on its hand, the wind pressure causes the workpiece to move as if it is being turned over on the hand, which results in a change in the position of the workpiece on the hand, and in severe cases, the workpiece may fall off the hand. In some cases, suction pads are provided to fix the position of the workpiece on the hand, but the force generated by the wind pressure is such that it pries open the gap between the suction pad and the workpiece, and this force may cause the workpiece to detach from the suction pad. In order to reduce the effect of wind pressure, it is sufficient to slow down the movement speed of the hand, i.e., the movement speed of the robot, but this increases the time required to transport the workpiece, which increases the takt time.

[0006] An object of the present invention is to provide an industrial robot and a control method thereof that can prevent the tact time from becoming excessively long, even when transporting a large, thin workpiece, while suppressing the effects of wind pressure and securely holding the workpiece in the hand. [Means for solving the problem]

[0007] The industrial robot of the present invention has a specified value for the operating speed. Plate-shaped Work While keeping the work horizontal The present invention relates to an industrial robot for transporting a workpiece, the robot comprising: a base; a hand capable of holding a workpiece; and a connecting member for connecting the hand. , which can rotate in a horizontal plane an arm, an arm support section that supports the arm, a lifting mechanism that raises and lowers the arm support section relative to the base, and When each axis is operated, control is performed so that each axis moves at a specified value. A control unit that performs control to change the position of the hand, The hand is attached to the arm so as to be rotatable within a horizontal plane; The control unit executes a deceleration process to change the position of the hand based on an operating speed that is smaller than a specified value when it receives an operating command that includes lowering the arm support part if the hand is of a type that holds a workpiece on top of the hand, and when it receives an operating command that includes raising the arm support part if the hand is of a type that holds a workpiece below the hand.

[0008] When a plate-like workpiece such as a glass substrate is transported, the workpiece is placed horizontally on the hand or held horizontally below the workpiece by suction or other means. In this state, even if the hand and the workpiece are moved horizontally, the workpiece is hardly subjected to wind pressure. When the hand is moved vertically, the workpiece is subjected to wind pressure, but even when the wind pressure applies a force that presses the workpiece against the hand, the workpiece does not shift in position on the hand or fall off from the hand. On the other hand, when the workpiece is subjected to wind pressure in a direction away from the hand, that is, when the arm support part descends if the hand is of a type that holds the workpiece on the hand, or when the arm support part ascends if the hand is of a type that holds the workpiece below the hand, the workpiece may shift in position or fall off. On the other hand, in an industrial robot, a specified value of the operating speed is set for each axis or for the entire robot, and when each axis is operated based on an operating command, each axis is driven to move at the specified value except for the period of acceleration and deceleration. Therefore, when the industrial robot of the present invention receives an operation command that causes the workpiece to receive wind pressure in a direction away from the hand, it executes a deceleration process that changes the position of the hand at an operation speed slower than a specified value. As a result, the wind pressure received by the workpiece during the movement of the hand is reduced, making it possible to prevent the workpiece from shifting out of position or falling off. In addition, since the deceleration process is not executed when there is no risk of the workpiece being shifted out of position or falling off, it is possible to minimize the increase in the overall takt time.

[0009] In the industrial robot of the present invention, it is preferable that the control unit executes the deceleration process only when the hand is holding a workpiece. When the hand is not holding a workpiece, the workpiece will not be displaced or separated from the hand in the first place, so by not executing the deceleration process at such times, it is possible to shorten the takt time. In addition, it is preferable that the control unit executes the deceleration process only when the amount of elevation of the arm support part by the operation command exceeds a predetermined value. When the amount of elevation of the arm support part is small, the maximum value of the elevation speed of the hand does not become large considering the acceleration and deceleration time, and in such a case, there is no risk of the workpiece being displaced or separated from the hand. Therefore, by not executing the deceleration process when the amount of elevation of the arm support part by the operation command is small, it is possible to shorten the takt time. In addition, in the industrial robot of the present invention, it is preferable that the deceleration process is a process of driving and controlling an axis related to the elevation of the arm support part of the industrial robot based on an operation speed that is smaller than a specified value set for that axis. By controlling the speed of only the axis related to the raising and lowering of the arm support part to be slowed down, when an operation command is to lower the arm support part while rotating, for example, the rotation speed does not decrease, so it is possible to prevent the tact time from being extended when the amount of rotation is large.

[0010] The industrial robot of the present invention may be equipped with a mechanism for moving the base horizontally along a rail, or may be equipped with a mechanism for rotating the lifting mechanism relative to the base around a vertical rotation axis. Furthermore, the industrial robot of the present invention may be equipped with an articulated mechanism in which the arm support section and the arm can move the hand forward and backward along a predetermined direction while fixing the orientation of the hand relative to the arm support section in the predetermined direction. Depending on the configuration of the industrial robot, various aerodynamic forces such as lift act on the workpiece held by the hand as the hand moves, but according to the present invention, it is possible to prevent the workpiece from shifting in position in the hand or from coming off the hand in various industrial robots.

[0011] The method for controlling an industrial robot of the present invention includes: Plate-shaped A hand that can hold a workpiece and a robot to which the hand is connected , which can rotate in a horizontal plane The arm includes an arm support portion that supports the arm, and a lifting mechanism that lifts and lowers the arm support portion relative to a base, The hand is attached to an arm so as to be rotatable within a horizontal plane, and a specified value for the operating speed is set, and each axis is controlled so that it moves at the specified value when operating each axis in response to an operating command. Work While keeping the work horizontal A control method for a transporting industrial robot, which executes a deceleration process to change the position of the hand based on an operating speed lower than a specified value when an operating command including lowering an arm support part is received if the hand is of a type that holds a workpiece on the hand, and when an operating command including raising the arm support part is received if the hand is of a type that holds a workpiece below the hand.

[0012] In the control method for an industrial robot of the present invention, when an operation command is received that causes the workpiece to receive wind pressure in a direction away from the hand, a deceleration process is executed to change the position of the hand at an operation speed slower than a specified value. As a result, the wind pressure received by the workpiece during the movement of the hand is reduced, and it is possible to prevent the workpiece from shifting out of position or coming off. In addition, since the deceleration process is not executed when there is no risk of the workpiece being shifted out of position or coming off, it is possible to minimize the increase in the overall takt time.

[0013] In the control method of the present invention, it is preferable to execute the deceleration process only when the hand holds a workpiece, and it is also preferable to execute the deceleration process only when the amount of lift of the arm support part by the operation command exceeds a predetermined value. When the hand does not hold a workpiece, or when the amount of lift of the arm support part is small and the lifting speed of the workpiece does not increase considering the acceleration and deceleration time, the workpiece does not shift in position or fall off, so by not executing the deceleration process in such a case, it is possible to shorten the takt time. In this control method, it is preferable to perform a process of driving and controlling an axis related to the lifting and lowering of the arm support part of an industrial robot based on an operating speed that is smaller than a specified value set for that axis. By controlling the speed of only the axis related to the lifting and lowering of the arm support part to be slow, it is possible to further prevent the takt time from becoming long. Effect of the Invention

[0014] According to the present invention, even when transporting a large, thin workpiece, it is possible to prevent the tact time from becoming excessively long, suppress the effects of wind pressure, and securely hold the workpiece in the hand. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a configuration of an industrial robot according to an embodiment of the present invention; [Diagram 2] 1A and 1B are a side view and a plan view, respectively, of the robot part. [Diagram 3] 10 is a flowchart showing a method for controlling the movement speed of the robot unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an industrial robot according to an embodiment of the present invention. This industrial robot is intended to transport a substantially rectangular plate-like workpiece such as a glass substrate, and includes a robot section 10 that performs actual operations as a horizontal articulated robot, and a control device (robot controller) 40 that receives an operation command for the robot section 10 from the outside and drives and controls the robot section 10 based on the operation command, and the robot section 10 and the control device 40 are electrically connected by a cable. The robot section 10 is configured as a so-called double-handed robot that includes two hands 13A and 13B that each hold a workpiece 50 (not shown in FIG. 1). FIG. 1 shows a state in which the horizontal articulated mechanism in the robot section 10 is raised. The control device 40 includes a control section 41 to which an operation command is input, and a drive circuit 42 including a servo driver and the like that drives each motor (not shown) provided in the robot section 10. Since the industrial robot of this embodiment is used to transport the workpiece 50, the operation command is basically a command to move the hands 13A, 13B to a certain position. Therefore, the control unit 41 generates a command including a speed for each axis of the robot unit 10 based on the operation command, and the drive circuit 42 actually drives the motor of each axis of the robot unit 10 based on the command for each axis.

[0017] FIG. 2 is a diagram showing details of the robot section 10 in a state where the horizontal articulated mechanism is lowered, and (a) and (b) are a side view and a plan view of the robot section 10, respectively. The robot section 10 includes a base 22 that can move on a pair of parallel rails 21 that are provided in a straight line on the floor surface, a rotating table 23 that is provided on the base 22 and rotates around a rotation axis 31 in a horizontal plane by a motor (not shown) built into the base 22, and a lifting mechanism 24 that is provided upright relative to the rotating table 23. A cover 25 that covers the rails 21 is attached. The lifting mechanism 24 includes a fixed part 24A that is attached to the rotating table 23, and a moving part 24B that moves up and down relative to the fixed part 24A by a motor (not shown). FIG. 2(a) shows the robot of this embodiment in a state where the moving part 24B of the lifting mechanism 24 is located at the lowest position in its lifting range, while FIG. 1 shows the robot in a state where the moving part 24B is raised. The moving section 24B is provided with an arm support section 26 that holds the horizontal multi-joint mechanism so as to extend in the horizontal direction, and two sets of horizontal multi-joint mechanisms are attached to the tip of the arm support section 26 in an array in the vertical direction. The upper horizontal multi-joint mechanism includes a first arm 11A that is attached to the arm support section 26 and can rotate in a horizontal plane around a common shaft 32, and a second arm 12A that is attached to the tip of the first arm 11A and can rotate in a horizontal plane around a shaft 33A, and a hand 13A is attached to the tip of the second arm 12A. Similarly, the lower horizontal multi-joint mechanism includes a first arm 11B that is attached to the arm support section 26 and can rotate in a horizontal plane around a common shaft 32, and a second arm 12B that is attached to the tip of the first arm 11B and can rotate in a horizontal plane around a shaft 33B, and a hand 13B is attached to the tip of the second arm 12B.

[0018] The hands 13A and 13B are in the shape of a fork with multiple rod-shaped members arranged in parallel so that the plate-shaped workpiece 50 can be transported while being kept horizontal by holding it from below. That is, the hands 13A and 13B are of a type that holds the workpiece 50 on the hands 13A and 13B. The hands 13A and 13B move forward or backward with respect to the workpiece 50 when taking out the workpiece 50 stored in a load lock chamber or the like and holding it on the hands 13A and 13B, or storing the held workpiece 50 in a load lock chamber or the like, and the direction in which the hands 13A and 13B move forward or backward is parallel to the direction in which the rod-shaped members extend. The width of the hands 13A and 13B in the left-right direction, i.e., the direction perpendicular to the front-rear direction, is shorter than the left-right width of the workpiece 50 to be transported.

[0019] In this robot, the horizontal articulated mechanism is configured such that the hands 13A, 13B move forward and backward in a linear motion in a direction perpendicular to the direction in which the arm support 26 extends, by a link mechanism incorporated in the first arms 11A, 11B and the second arms 12A, 12B. That is, both hands 13A, 13B move forward and backward in the same direction. The movement of the tips of the hands 13A, 13B away from the central axis 32 is the forward movement, and the movement in the opposite direction to the forward movement is the backward movement. The first arms 11A, 11B and the second arms 12A, 12B perform bending movements as a whole, and in order to keep the orientation of the hands 13A, 13B constant in the horizontal plane, the hands 13A, 13B are attached at the tips of the second arms 12A, 12B so as to be rotatable in the horizontal plane around the wrist axes 34A, 34B, respectively. In the upper horizontal multi-joint mechanism, a motor (not shown) provided in the arm support section 26 is driven to move the first arm 11A and the second arm 12A, and the hand 13A moves in a direction perpendicular to the extension direction of the arm support section 26 while maintaining its orientation. Similarly, in the lower horizontal multi-joint mechanism, a motor (not shown) provided in the arm support section 26 is driven to move the first arm 11B and the second arm 12B, and the hand 13B moves in a direction perpendicular to the extension direction of the arm support section 26 while maintaining its orientation. In this robot, the hands 13A and 13B can be moved forward and backward independently.

[0020] In the end, the movement of the robot section 10 of the industrial robot of this embodiment can be broken down into horizontal movement along the rail 21 (this is the X-axis or travel axis movement), rotation around the vertical axis of rotation 31 relative to the base (this is the θ-axis or pivot axis movement), horizontal forward and backward movement of the hands 13A, 13B (this is the R-axis movement), and vertical lifting and lowering of the arm support section 26 by the lifting mechanism 24 (this is the Z-axis movement). The robot section 10 executes an operation to move only one of these axes or an operation to move two or more axes simultaneously by drive control from the control device 40 in response to an operation command. A specified value of the operation speed is set for each axis or for the entire axis for the movement of these axes. The specified value of the operation speed corresponds to, for example, the maximum speed when the corresponding axis is moved, and when the control section 41 of the control device 40 operates each axis based on an operation command, it generally controls each axis to move at the specified value except for the period of acceleration and deceleration. The control device 40 performs servo control of each motor (not shown) in the robot unit 10, and the specified value of the motion speed on each axis does not depend on the direction of movement on that axis. Specifically, for the R axis, the specified value for the forward movement and the backward movement of the hands 13A, 13B is the same, and for the Z axis, the specified value when the arm support unit 26 is raised is the same as the specified value when it is lowered.

[0021] The transportation of a work 50 such as a glass substrate using the industrial robot of this embodiment will be described. When the industrial robot of this embodiment transports the work 50 between processing devices, the cassettes (or load lock chambers) of each processing device are arranged at positions that are approximately equidistant from the rails 21 in the horizontal direction. The vertical position (height) of the cassette is arbitrary as long as it is within a range that can be handled by the lifting mechanism 24. The cassettes may be arranged on both sides of a track consisting of a pair of rails 21. When the work 50 is transported from the first cassette on the unloading side to the second cassette on the loading side by placing the work 50 on the hand 13A, the robot unit 10 is moved along the rails 21 to a position facing the first cassette with both the hands 13A and 13B retreated and the first arms 11A and 11B and the second arms 12A and 12B folded, and the arm support unit 26 is raised and lowered by the lifting mechanism 24 so that the height of the hand 13A corresponds to the height of the first cassette. Then, the hand 13A is advanced to enter the first cassette, and the hand 13A is raised slightly to place the workpiece 50 on the hand 13A. After that, the hand 13A is retreated to pull the hand 13A together with the workpiece 50 out of the first cassette. Next, the robot unit 10 is moved along the rail 21 to a position facing the second cassette with the workpiece 50 mounted thereon, and the arm support unit 26 is raised and lowered by the lifting mechanism 24 so that the height of the hand 13A corresponds to the height of the second cassette. When the robot unit 10 is moved to the rail 21, the arm support unit 26 can be raised and lowered at the same time. When teaching the robot unit 10, it is common to perform horizontal movement and lifting and lowering at the same time, and this shortens the tact time when actually transporting the workpiece 50. Then, the hand 13A with the workpiece 50 placed thereon is advanced to enter the second cassette, the hand 13A is lowered slightly to place the workpiece 50 in the second cassette, and the hand 13A is then retreated to pull out the hand 13A from the second cassette. Through the above operations, the workpiece 50 is transported from the first cassette to the second cassette.When a first cassette is placed on one side of a track consisting of a pair of rails 21 and a second cassette is placed on the other side, in addition to the above operations, a rotation operation around a rotation axis 31 is also performed.

[0022] The transportation of the workpiece 50 by the robot section 10 has been described. However, there is a risk that the position of the workpiece 50 on the hands 13A and 13B may be displaced or the workpiece 50 may fall off from the hands 13A and 13B due to wind pressure during transportation. Therefore, in this embodiment, control is performed to prevent the workpiece 50 from being displaced or falling off. In the industrial robot of this embodiment, the workpiece 50 is placed on the hands 13A and 13B. If the hands 13A and 13B are moving horizontally, almost no wind pressure is applied to the workpiece 50, and the workpiece 50 does not become displaced or fall off. When the hands 13A and 13B are rising, the wind pressure acts in a direction that presses the workpiece 50 against the hands 13A and 13B, so the workpiece 50 does not become displaced or fall off. On the other hand, when the hands 13A and 13B are descending, the workpiece 50 is lifted up on the hands 13A and 13B, and a force that turns it over acts on the workpiece 50, making it more likely that the workpiece 50 will become displaced or fall off. When the workpiece 50 descends with horizontal or turning motion, an aerodynamic lift is applied to the workpiece 50, so that the workpiece 50 is also likely to become displaced or fall off at this time.

[0023] In this embodiment, when the robot unit 10 is operated based on a motion command, if the motion command includes lowering the arm support unit 26, the motion of the robot unit 10 based on the motion command is controlled using a motion speed (reduced speed) smaller than the specified value of the motion speed. A motion command including lowering the arm support unit 26 means not only a motion command to only lower the arm support unit 23, i.e., to move only the Z axis, but also a motion command to simultaneously move multiple axes including the Z axis, for example, a motion command to lower the arm support unit 23 while moving the robot unit 10 horizontally (while moving the X axis). Controlling the motion of the robot unit 10 using a reduced speed smaller than the specified value of the motion speed is called deceleration processing. In the deceleration processing, for example, a speed that is 70% of the specified value is set as the reduced speed, and control is performed such that at least the Z axis of the robot operates at the reduced speed during a period excluding acceleration and deceleration times. The extent to which the reduced speed is reduced from the specified value is determined appropriately depending on the configuration of the robot unit 10 (especially whether or not a member for suction is used and the material of the part of the hand that contacts the workpiece) and the size of the workpiece 50. The specified value for each axis and the ratio of the reduced speed value to the specified value are stored in advance in the control unit 41. Although the reduced speed may be applied to all axes in the deceleration process, the takt time is generally shorter if the reduced speed is applied only to the Z axis related to the raising and lowering of the arm support unit 23. As described above, if the deceleration process is not performed, the specified values ​​of the operating speeds for the raising and lowering of the Z axis are generally equal, so by performing the deceleration process, the maximum speed during the lowering movement becomes lower than the maximum speed during the raising movement.

[0024] FIG. 3 is a flow chart showing a method of controlling the robot section 10 of the industrial robot of this embodiment, and shows the operation when the control section 41 performs deceleration processing. When an operation command for the robot section 10 is input to the control device 40, first in step 101, the control section 41 analyzes the operation command and checks which axis is intended to be moved and how much. The analysis of the operation command in step 101 is a process required for driving each axis of the robot section 10 by the control device 40, regardless of whether deceleration processing is performed or not. Next, in step 102, the control section 41 determines whether the workpiece 50 is placed on the hands 13A and 13B. The determination of whether the workpiece 50 is placed on the hands 13A and 13B may be based on the output of a contact sensor (not shown) provided on the hands 13A and 13B, or may be based on the result of analyzing a series of input operation commands. Here, when the workpiece 50 is not placed on the hands 13A and 13B, the workpiece 50 is not likely to be displaced or fall off, and therefore it is not necessary to perform deceleration processing. The process proceeds to step 106. It is also possible to configure the system so that the determination in step 102 is not performed and the deceleration process is performed when the arm support portion 26 is lowered regardless of whether the workpiece 50 is present or not.

[0025] When it is determined in step 102 that the workpiece 50 is placed on the hands 13A and 13B, the control unit 41 determines in step 103 whether the operation command is an operation command including the lowering operation of the arm support unit 26. When the operation command does not include the lowering operation of the arm support unit 26, it is not necessary to perform the deceleration process, and the process proceeds to step 106. When it is determined in step 103 that the operation command includes the lowering operation of the arm support unit 26, it is next determined in step 104 whether the lowering amount is equal to or greater than a predetermined value. When the lowering amount of the arm support unit 26 is small, such as when unloading the workpiece 50 in a cassette, the maximum value of the lowering speed of the hands 13A and 13B is also small when the acceleration and deceleration time is taken into consideration, and in such a case, there is no risk of the workpiece 50 being displaced or falling off, so it is not necessary to perform the deceleration process. In addition, when the reduced speed is set by performing the deceleration process, the acceleration and deceleration may be affected. Therefore, when the lowering amount is not equal to or greater than the predetermined value, the deceleration process is not performed, and the process of step 106 is then executed. On the other hand, if the amount of descent of the arm support part 26 is equal to or greater than a predetermined amount, the process of step 105 is executed to execute the deceleration process. Note that it is also possible to configure the process to execute the deceleration process when the arm support part 26 is lowered, regardless of the amount of descent, without making the determination in step 104.

[0026] In step 105, the control unit 41 performs deceleration processing by setting a reduced speed to, for example, 70% of the specified value of the robot's motion speed, and performs drive control of each axis based on the motion command while applying this reduced speed to at least the Z axis. When drive control based on the motion command is completed, the process returns to step 101 to execute control based on the next motion command. On the other hand, in step 106, the control unit 41 performs drive control of each axis based on the motion command while applying the specified value of the robot's motion speed as is, and when drive control based on the motion command is completed, the process returns to step 101 to execute control based on the next motion command.

[0027] In the industrial robot of the present embodiment described above, when an operation command including lowering the arm support unit 26 is received, a deceleration process is performed to change the position of the hand based on an operation speed (reduced speed) lower than a specified value, thereby weakening the wind pressure received by the workpiece 50 and preventing the workpiece 50 from being displaced or falling off. The reduced speed is applied to control at least the Z axis, i.e., the movement of lowering the arm support unit 26. As a method for preventing the workpiece from being displaced or falling off due to wind pressure, it is possible to reduce the specified value of the robot's operation speed itself according to the size of the workpiece and the configuration of the robot, and to operate the robot slowly in response to all operation commands. However, in this embodiment, the deceleration process is performed only when an operation command that may cause the workpiece 50 to be displaced or fall off is executed, so that an increase in takt time can be significantly suppressed.

[0028] The above-mentioned industrial robot transports the workpiece 50 by placing it on the hands 13A, 13B, but the present invention can also be applied to an industrial robot that holds the workpiece 50 below the hands 13A, 13B using some kind of suction or adsorption means. In such a case, when an operation command including lifting the arm support part 26 is received, deceleration processing can be performed so that a reduced speed is applied at least to the lifting of the arm support part 26. [Explanation of symbols]

[0029] 10...robot part; 11A, 11B...first arm; 12A, 12B...second arm; 13A, 13B...hand; 21...rail; 22...base; 23...rotating table; 24...lifting mechanism; 24A...fixed part; 24B...moving part; 25...cover; 26...arm support part; 31...rotating axis; 32...common axis; 33A, 33B...axis; 34A, 34B...wrist axis; 40...control device; 41...control part; 42...drive circuit; 50...work.

Claims

1. An industrial robot having a specified value for the operating speed and capable of transporting a plate-shaped workpiece while maintaining the workpiece in a horizontal state, The base and A hand capable of holding a workpiece; an arm to which the hand is connected and which is rotatable within a horizontal plane; an arm support portion that supports the arm; a lifting mechanism for lifting and lowering the arm support part relative to the base; a control unit that executes control so that each axis moves at the specified value when each axis is operated in response to an operation command, and controls to change the position of the hand; Equipped with The hand is attached to the arm so as to be rotatable within a horizontal plane, The control unit executes a deceleration process to change the position of the hand based on an operating speed that is smaller than the specified value when the control unit receives the operating command including lowering the arm support part if the hand is of a type that holds the workpiece on top of the hand, and when the control unit receives the operating command including raising the arm support part if the hand is of a type that holds the workpiece below the hand.

2. The industrial robot according to claim 1 , wherein the control unit executes the deceleration process only when the hand is holding the workpiece.

3. The industrial robot according to claim 1 , wherein the control unit executes the deceleration process only when an amount of lifting of the arm support unit in response to the operation command exceeds a predetermined value.

4. 4. The industrial robot according to claim 1, wherein the deceleration process is a process of controlling the drive of an axis related to the lifting and lowering of the arm support part of the industrial robot based on an operating speed that is lower than a specified value determined for the axis.

5. 5. The industrial robot according to claim 1, further comprising a mechanism for moving the base horizontally along a rail.

6. 6. The industrial robot according to claim 1, further comprising a mechanism for rotating the lifting mechanism relative to the base about a vertical axis of rotation.

7. 7. The industrial robot according to claim 1, wherein the arm support portion and the arm form a multi-joint mechanism that can move the hand forward and backward along a predetermined direction while fixing an orientation of the hand relative to the arm support portion in the predetermined direction.

8. A control method for an industrial robot comprising: a base, a hand capable of holding a plate-shaped workpiece, an arm to which the hand is connected and rotatable within a horizontal plane, an arm support section supporting the arm, and a lifting mechanism for raising and lowering the arm support section relative to the base, the hand being attached to the arm so as to be rotatable within a horizontal plane, a prescribed value for an operating speed being set, and each axis being controlled so as to move at the prescribed value when each axis is operated in response to an operation command, thereby transporting the workpiece while maintaining the horizontal state of the workpiece, A method for controlling an industrial robot, comprising: executing a deceleration process for changing the position of the hand based on an operating speed that is smaller than the specified value when receiving an operating command that includes lowering the arm support part if the hand is of a type that holds the workpiece on the hand; and when receiving an operating command that includes raising the arm support part if the hand is of a type that holds the workpiece below the hand.

9. The method for controlling an industrial robot according to claim 7 , wherein the deceleration process is executed only when the hand is holding the workpiece.

10. 9. The method for controlling an industrial robot according to claim 7, further comprising the step of: executing the deceleration process only when an amount of elevation of the arm support part in response to the operation command exceeds a predetermined value.

11. 11. The method for controlling an industrial robot according to claim 8, wherein the deceleration process is a process for controlling the drive of an axis related to the lifting and lowering of the arm support part of the industrial robot based on an operating speed that is lower than a specified value set for the axis.

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