JP7599302B2 - Industrial robot and control method thereof - Google Patents

Description

The present invention relates to an industrial robot that transports plate- or sheet-shaped workpieces, such as glass substrates used in liquid crystal display panels and organic EL (electroluminescence) panels, and a control method for the same.

For example, in a manufacturing line for liquid crystal display panels used in liquid crystal display devices, a robot is used to transport plate-shaped workpieces such as glass substrates 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 from the cassette, moving the arm of the robot or the entire robot with the workpiece still on the hand, then inserting the hand into a cassette of the processing device that is the destination of the workpiece and storing 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 is, for example, equipped with a horizontal multi-joint mechanism consisting of two connected 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 around a vertical axis as the axis of rotation. 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 within the horizontal plane, the horizontal articulated mechanism must be rotated using a rotation mechanism. In addition, a transport mechanism is provided to move the entire robot in a straight line within the horizontal plane.

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 misalignment of a large workpiece that has a large amount of deflection on the hand, in which the hand is provided with multiple rubber or resin pads with contact surfaces that come into contact with the underside of the workpiece, and the contact surfaces of the pads are spherical.

JP 2015-217509 A

As workpieces become larger and thinner, it is becoming increasingly difficult to ignore the effects of wind pressure on workpieces when they are being transported by a robot. When a robot 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, resulting in a change in the position of the workpiece on the hand and, in severe cases, the workpiece falling from the hand. Suction pads are sometimes provided to fix the position of the workpiece on the hand, but the force generated by the wind pressure is strong enough to pry the gap between the suction pad and the workpiece, and this force can cause the workpiece to detach from the suction pad. In order to reduce the effects of wind pressure, the movement speed of the hand, i.e. the movement speed of the robot, can be reduced, but this increases the time required to transport the workpiece and therefore the takt time.

The object of the present invention is to provide an industrial robot and a control method thereof that can hold a workpiece securely in the hand while suppressing the effects of wind pressure and preventing the takt time from becoming excessively long, even when transporting a large, thin workpiece.

The industrial robot of the present invention is an industrial robot that has a specified value for the operating speed and transports a plate-shaped workpiece while maintaining the workpiece in a horizontal position , and is equipped with a base, a hand capable of holding the workpiece, an arm to which the hand is connected and which can rotate in a horizontal plane , an arm support section that supports the arm, a lifting mechanism that raises and lowers the arm support section relative to the base, and a control section that executes control so that each axis moves at a specified value when each axis is operated in response to an operation command and controls to change the position of the hand , the hand being attached to the arm so as to be rotatable in a horizontal plane, and the control section executes a deceleration process to change the position of the hand based on an operating speed that is smaller than the specified value when it receives an operation command that includes lowering the arm support section if the hand is of a type that holds a workpiece on top of the hand, and when it receives an operation command that includes raising the arm support section if the hand is of a type that holds a workpiece below the hand.

When transporting a plate-like workpiece such as a glass substrate, 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 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 in the hand or fall off from the hand. In contrast, 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 a type that holds the workpiece on the hand, or when the arm support part ascends if the hand is a type that holds the workpiece below the hand, the workpiece may shift in position or fall off. On the other hand, in industrial robots, a specified value for 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 that specified value except for the period of acceleration and deceleration. Therefore, when the industrial robot of the present invention receives an operation command in which the workpiece is subjected to wind pressure in a direction away from the hand, it executes a deceleration process that changes the position of the hand at an operating speed slower than a specified value. As a result, the wind pressure received by the workpiece during the hand movement is reduced, making it possible to prevent the workpiece from shifting out of position or becoming detached. In addition, since the deceleration process is not executed when there is no risk of the workpiece becoming detached or becoming detached, it is possible to minimize the overall increase in takt time.

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 removed 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 lifting and lowering of the arm support part by the operation command exceeds a predetermined value. When the amount of lifting and lowering of the arm support part is small, the maximum value of the lifting and lowering 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 removed. Therefore, by not executing the deceleration process when the amount of lifting and lowering of the arm support part by the operation command is small, it is possible to shorten the takt time. Furthermore, 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 lifting and lowering of the arm support part in the industrial robot based on an operation speed that is smaller than the 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 slow down, for example when an operation command is to lower the arm support part while rotating, 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.

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 axis of rotation. Furthermore, the industrial robot of the present invention may be equipped with an articulated mechanism in which the arm support 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. Depending on the configuration of the industrial robot, various aerodynamic forces such as lift act on the work held by the hand as the hand moves, but according to the present invention, it is possible to prevent the work from shifting from the hand or from coming off the hand in various industrial robots.

The control method for an industrial robot of the present invention is an industrial robot having a base, a hand capable of holding a plate-shaped workpiece, an arm to which the hand is connected and which can rotate in a horizontal plane , an arm support part supporting the arm, and a lifting mechanism for raising and lowering the arm support part relative to the base , wherein the hand is attached to the arm so as to be rotatable in a horizontal plane, and a specified value for the operating speed is set, and when each axis is operated in response to an operation command, each axis is controlled so that it moves at the specified value , thereby transporting the workpiece while maintaining its horizontal state , and when an operation command is received 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 an operation command is received that includes raising the arm support part if the hand is of a type that holds a workpiece below the hand, a deceleration process is performed to change the position of the hand based on an operating speed that is smaller than the specified value.

In the control method for an industrial robot of the present invention, when an operational command is received that causes the workpiece to be subjected to wind pressure in a direction away from the hand, a deceleration process is executed to change the position of the hand at an operational 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 becoming detached. In addition, since the deceleration process is not executed when there is no risk of the workpiece becoming shifted out of position or becoming detached, it is possible to minimize the overall increase in takt time.

In the control method of the present invention, it is preferable to execute the deceleration process only when the hand is holding a workpiece, and it is also preferable to execute the deceleration process only when the amount of elevation of the arm support part by the operation command exceeds a predetermined value. When the hand is not holding a workpiece, or when the amount of elevation of the arm support part is small and the elevation 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 cases, it is possible to shorten the takt time. In this control method, it is preferable that the process is a process of driving and controlling an axis related to the elevation of the arm support part of an industrial robot based on an operating speed that is smaller than the specified value set for that axis. By controlling the speed of only the axis related to the elevation of the arm support part to be slow, it is possible to further prevent the takt time from becoming longer.

According to the present invention, even when transporting large, thin workpieces, it is possible to prevent the tact time from becoming excessively long, while suppressing the effects of wind pressure and securely holding the workpiece in the hand.

1 is a diagram showing a configuration of an industrial robot according to an embodiment of the present invention; 1A and 1B are a side view and a plan view, respectively, of the robot part. 10 is a flowchart showing a method for controlling the movement speed of the robot unit.

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-shaped 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 operation commands for the robot section 10 from the outside and drives and controls the robot section 10 based on the operation commands, 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 is raised in the robot section 10. The control device 40 includes a control section 41 to which operation commands are input, and a drive circuit 42 including a servo driver 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 and 13B to a certain position. Therefore, the control unit 41 generates a command including the 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.

2 is a diagram showing details of the robot part 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 part 10, respectively. The robot part 10 is equipped with 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 in a horizontal plane around a rotating shaft 31 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 rail 21 is attached. The lifting mechanism 24 is equipped with 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, which extends horizontally, 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 axis 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 an axis 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 axis 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 an axis 33B, and a hand 13B is attached to the tip of the second arm 12B.

The hands 13A and 13B are fork-shaped 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 relative 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-back direction, is shorter than the left-right width of the workpiece 50 to be transported.

In this robot, the horizontal articulated mechanism is configured such that the hands 13A, 13B move forward and backward in a linear motion perpendicular to the direction in which the arm support 26 extends, by a link mechanism incorporated in the first arm 11A, 11B and the second arm 12A, 12B. In other words, 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 forward movement, and the movement in the opposite direction to the forward movement is 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 on 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 on 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.

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 and 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 operating speed is set for each axis or for the entire axis for the movements of these axes. The specified value of the operating speed corresponds to, for example, the maximum speed when moving the corresponding axis, 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 operating speed for 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 of the hands 13A, 13B is the same as the specified value for the backward movement, and for the Z axis, the specified value for raising the arm support unit 26 is the same as the specified value for lowering it.

The following describes the transportation of a workpiece 50 such as a glass substrate using the industrial robot of this embodiment. When the industrial robot of this embodiment transports the workpiece 50 between processing devices, the cassettes (or load lock chambers) of each processing device are arranged at approximately equal distances from the rail 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 workpiece 50 is transported from the first cassette on the unloading side to the second cassette on the loading side by placing the workpiece 50 on the hand 13A, the robot unit 10 is moved along the rail 21 to a position facing the first cassette with both 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 retracted 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 simultaneously perform horizontal movement and lifting and lowering, and this shortens the tact time when actually transporting the workpiece 50. Then, with the workpiece 50 still on it, the hand 13A 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 retracted to pull the hand 13A out of the second cassette. Through the above operations, the workpiece 50 is transported from the first cassette to the second cassette. When the first cassette is placed on one side of the track consisting of a pair of rails 21 and the second cassette is placed on the other side, in addition to the above operations, a rotation operation around the rotation axis 31 is performed.

The transportation of the workpiece 50 by the robot unit 10 has been described, but there is a risk that the position of the workpiece 50 on the hands 13A and 13B may shift or 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 shifting 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 shift or fall off. When the hands 13A and 13B are rising, wind pressure acts in a direction that presses the workpiece 50 against the hands 13A and 13B, so the workpiece 50 does not shift 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 easier for the workpiece 50 to shift or fall off. When the workpiece 50 descends with horizontal or rotating motion, aerodynamic lift is applied to the workpiece 50, so the workpiece 50 is also prone to shifting or falling off.

Therefore, in this embodiment, when the robot part 10 is operated based on a motion command, if the motion command includes lowering the arm support part 26, the motion of the robot part 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 part 26 means not only a motion command to only lower the arm support part 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 move the robot part 10 horizontally (while moving the X axis) and lower the arm support part 23 at the same time. Controlling the motion of the robot part 10 using a reduced speed smaller than the specified value of the motion speed is called deceleration processing. In deceleration processing, for example, a speed that is 70% of the specified value is set as the reduced speed, and control is performed so that at least the Z axis of the robot operates at the reduced speed during the period excluding the acceleration and deceleration time. The extent to which the reduced speed is reduced from the specified value is determined appropriately depending on the configuration of the robot part 10 (especially whether or not a member for suction is used and the material of the contact part of the hand with 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, applying the reduced speed only to the Z axis related to the raising and lowering of the arm support unit 23 generally shortens the takt time. As described above, if the deceleration process is not performed, the specified values for the operating speeds for the rising and lowering of the Z axis are generally equal, so by performing the deceleration process, the maximum speed during descent is lower than the maximum speed during ascent.

Figure 3 is a flow chart showing a method for 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 necessary for the control device 40 to drive each axis of the robot section 10, 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 cannot be displaced or fall off, and therefore there is no need to perform deceleration processing. The process proceeds to step 106. It is also possible to configure the system so that deceleration processing is performed when the arm support portion 26 descends, regardless of whether or not a workpiece 50 is present, without making the determination in step 102.

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 there is no need to perform the deceleration process. In addition, when the reduction 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 system so that the deceleration process is executed when the arm support part 26 is lowered, regardless of the amount of descent, without making the determination in step 104.

In step 105, the control unit 41 performs deceleration processing by setting the 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 still applying the specified value of the robot's motion speed, 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.

In the industrial robot of the present embodiment described above, when an operation command including lowering the arm support portion 26 is received, a deceleration process is performed to change the position of the hand based on an operation speed (reduced speed) that is smaller than the 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 at least the Z axis, i.e., to control the movement of lowering the arm support portion 26. As a method of 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 depending on the size of the workpiece and the configuration of the robot, and operate the robot slowly for 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, making it possible to significantly suppress an increase in takt time.

The above-mentioned industrial robot transports the workpiece 50 by placing it on the hands 13A and 13B, but the present invention can also be applied to industrial robots that use some kind of suction or adsorption means to hold the workpiece 50 below the hands 13A and 13B. In such cases, 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 to at least the lifting of the arm support part 26.

10...Robot section; 11A, 11B...First arm; 12A, 12B...Second arm; 13A, 13B...Hand; 21...Rail; 22...Base; 23...Rotary table; 24...Lifting mechanism; 24A...Fixed section; 24B...Moving section; 25...Cover; 26...Arm support section; 31...Rotary axis; 32...Common axis; 33A, 33B...Axis; 34A, 34B...Wrist axis; 40...Control device; 41...Control section; 42...Drive circuit; 50...Work.

Claims (11)

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 the 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 lower 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. The industrial robot according to claim 1, wherein the control unit executes the deceleration process only when the hand is holding the workpiece. The industrial robot according to claim 1 or 2, wherein the control unit executes the deceleration process only when the amount of lift of the arm support unit in response to the operation command exceeds a predetermined value. The industrial robot according to any one of claims 1 to 3, wherein the deceleration process is a process of controlling the drive of an axis related to the elevation of the arm support part of the industrial robot based on an operating speed that is lower than a specified value set for that axis. The industrial robot according to any one of claims 1 to 4, further comprising a mechanism for moving the base horizontally along a rail. The industrial robot according to any one of claims 1 to 5, further comprising a mechanism for rotating the lifting mechanism relative to the base about a vertical axis of rotation. The industrial robot according to any one of claims 1 to 6, wherein the arm support and the arm form a multi-joint mechanism that can move the hand forward and backward along a predetermined direction while fixing the orientation of the hand relative to the arm support in the predetermined direction. 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. The method for controlling an industrial robot according to claim 7, wherein the deceleration process is performed only when the hand is holding the workpiece. The method for controlling an industrial robot according to claim 7 or 8, wherein the deceleration process is executed only when the amount of lift of the arm support part in response to the operation command exceeds a predetermined value. The method for controlling an industrial robot according to any one of claims 8 to 10, wherein the deceleration process is a process for controlling the drive of an axis related to the elevation of the arm support part of the industrial robot based on an operating speed that is lower than a specified value set for that axis.

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