JP7628048B2 - Work transport system and control method thereof - Google Patents

Description

The present invention relates to a workpiece transport system equipped with an articulated robot for transporting workpieces such as semiconductor wafers, and a control method thereof.

For example, in the semiconductor manufacturing process, workpieces such as semiconductor wafers need to be transported between a cassette that stores the workpieces and a workpiece processing device that performs a predetermined process on the workpieces. At this time, it is necessary to be able to load (carry in)/unload (carry out) the workpieces to multiple cassettes or multiple workpiece processing devices. In addition, the space in which the transport device can operate to transport the workpieces, i.e., the work area, is often limited. For this reason, the workpieces are often transported using a multi-joint robot in which multiple arms are rotatably connected to each other and the rotational force of a motor or the like is transmitted to the arms to perform operations such as extension and contraction. In the robot, the hand on which the workpieces are placed during transport is attached to the arm at the tip via a rotating shaft. The cassette, for example, is used to load and place the workpieces in a shelf-like manner, and has an opening on its front side facing the work area. By inserting the hand into the cassette through the opening, it is possible to load and unload the workpieces. Similarly, the workpiece processing device is also configured to have an opening facing the work area and to be able to load and unload the workpieces through the opening. A single workpiece transport system is made up of the cassette in which the workpieces are stored, the workpiece processing device, and the multi-joint robot. Cassettes are also used to load and unload workpieces from the work processing device, so they are collectively referred to as stages. To improve throughput in semiconductor manufacturing processes, etc., a work transport system that can transport workpieces between stages at high speed is required.

Patent Document 1 discloses that a horizontal articulated robot is used, and the robot is driven so that the third rotation axis counting from the hand side is positioned on the axis of access to the stage, and then the hand is moved in and out linearly relative to the stage, thereby loading and unloading workpieces at high speed without using a linear motion mechanism. In a work transport system, it is necessary to prevent the robot's arm or hand from colliding with the wall surfaces that partition the work area when the robot moves between stages, but Patent Document 2 by the present inventor discloses that several specified waypoints are predefined for the robot's posture, and the robot's movement path is determined to pass through the specified waypoints, in order to easily generate a safe path for the robot.

To shorten the transport time, it is necessary for the transport robot to move at high speed, and Patent Document 3 discloses a technique for speeding up the movement of a robot by dividing the acceleration section, constant velocity section, and deceleration section into segments when moving the robot in a straight line, and performing PTP control for each segment. Patent Document 4 discloses that when generating a trajectory for a robot arm, a group of intermediate teaching points is provided between a start teaching point and a target teaching point, and a trajectory is generated and evaluated based on the group of intermediate teaching points, while displacing the group of intermediate teaching points, and a trajectory is generated that passes through the group of intermediate teaching points with the best evaluation results.

By the way, there are two types of motion when moving a robot: PTP (Point To Point) motion and linear interpolation motion. Assuming that there is a reference point on the arm or hand of the robot, PTP motion is a motion in which the robot is moved by specifying only the start and end points of the trajectory drawn by the reference point. When the reference point is moved to the target coordinates, each axis of the robot is driven simultaneously to reach the target coordinates. In this case, the motors of each axis of the robot can be operated at the maximum speed specified in the specifications, so it is possible to reach the target coordinates in a short time, but the motion trajectory of the reference point is not a straight line, and the shape of the trajectory is not guaranteed. In order to prevent interference with walls, etc., it is necessary to increase the number of teaching points and perform PTP motion between adjacent teaching points. In contrast, linear interpolation motion is a motion in which the robot is moved by performing trajectory interpolation so that the motion trajectory of the reference point becomes a straight line when the reference point is moved to the target coordinates. Linear interpolation ensures that the trajectory is straight, but has the disadvantage that it takes longer to reach the target coordinates than PTP operation.

In the method described in the above-mentioned Patent Document 2, a standby/retraction position is set for each stage in the working area at a position on the near side of the front of the stage, and after the hand is moved to the standby/retraction position, the hand is moved straight toward the inside of the stage by linear interpolation. When moving between the standby/retraction position and a specified via point (or origin position), PTP operation is used. In the method described in Patent Document 1, the robot is also first driven so that the third rotation axis counting from the hand side positions the hand on the axis of access to the stage, but this position corresponds to the standby/retraction position in the method described in Patent Document 2, and the movement of the hand from this position to the inside of the stage must be linear, so linear interpolation operation that guarantees the shape of the trajectory is used.

JP 2011-119556 A JP 2019-84651 A JP 2019-166623 A JP 2019-135076 A

As shown in Patent Documents 1 and 2, in a workpiece transport system, when a standby/retraction position is set on the axis of access to the stage and outside the stage, the relationship between the standby/retraction position and the position inside the stage for loading and unloading the workpiece is easy to understand, and robot teaching can be easily performed. However, when the standby/retraction position is set in this way, the robot moves a large amount by linear interpolation, which is disadvantageous in shortening the transport time. In addition, when a robot is moved between a standby/retraction position of one stage and a standby/retraction position of another stage, PTP operation can be used, but in order to prevent the arm and hand of the robot from interfering with the inner wall of the working area when the arm of the robot rotates, the arm and hand must pass through a position in which they are folded to some extent (for example, the designated via point in Patent Document 2), which increases the robot's movement time.

The object of the present invention is to provide a workpiece transport system and a control method thereof that can reduce the time required to transport a workpiece compared to a case in which a standby/retraction position is set on the axis of access to the stage but outside the stage.

The work transport system of the present invention has a work area, multiple stages arranged adjacent to the work area, and a robot provided in the work area that loads/unloads workpieces to/from the multiple stages and transports the workpieces. A standby position and an operation switching point are determined for each stage. The operation switching point is a position where the stage is pulled back from the stage position toward the work area, and where a part of the robot or a part of the workpiece placed on the robot is inside the stage when the robot is at the operation switching point. The standby position is a position within the work area where the robot can turn directly to the standby position of another stage without interfering with the inner wall of the work area, and where the robot and the workpiece placed on the robot do not interfere with the inner wall of the work area or the inner wall of the stage even if the robot moves to the operation switching point of the stage corresponding to the standby position by point-to-point (PTP) operation. For each stage, the robot moves between the standby position and the operation switching point of the stage by PTP operation, and moves between the operation switching point of the stage and the stage position by linear interpolation operation.

According to the workpiece transport system of the present invention, an operation switching point is set at a position where a part of the robot or a part of the workpiece is inside the stage 20, the robot is moved by PTP operation between the standby position and the operation switching point, and the robot is moved by linear interpolation operation between the operation switching point and the stage position, so that the moving distance of the robot in the linear interpolation operation is shorter than that of the conventional workpiece transport system, and the time required for transporting the workpiece can be shortened. Also, since there is no need to fold the arms of the robot when moving between the standby position of one stage and the standby position of another stage, the transport time can be shortened.

In the workpiece transport system of the present invention, it is preferable for the robot to move between waiting positions using PTP operation. By moving the robot between waiting positions using PTP operation, it is possible to further reduce the transport time.

In the work transport system of the present invention, the robot is, for example, a horizontal articulated robot including a base, a base-side link rotatably connected to the base, an arm-side link connected to the base-side link, an arm rotatably connected to the arm-side link, and a hand rotatably connected to the arm to hold a work. In this horizontal articulated robot, the base-side link and the arm-side link form a link mechanism that regulates the movement trajectory of the center point of the connecting axis between the arm-side link and the arm so that it becomes a predetermined straight line. By applying the present invention to a work transport system including a horizontal articulated robot whose horizontal movement is greater than its vertical movement, it is possible to further shorten the transport time when the robot turns, and it is possible to significantly shorten the overall transport time.

The control method of the present invention is a method for controlling a robot in a work transport system having a work area, multiple stages arranged adjacent to the work area, and a robot provided in the work area for loading/unloading workpieces to/from the multiple stages to transport the workpieces, and a standby position and an operation switching point are determined for each stage, and when the robot is moved between the standby position for each stage and the stage position of the stage, the robot is moved between the standby position of the stage and the operation switching point by PTP operation, and the robot is moved between the operation switching point and the stage position of the stage by linear interpolation operation, the operation switching point is a position pulled back from the stage position of the stage toward the work area, and when the robot is at the operation switching point, a part of the robot or a part of the workpiece placed on the robot is inside the stage, and the standby position is a position in the work area where the robot can directly rotate to the standby position of another stage without interfering with the inner wall of the work area, and a position where the robot and the workpiece placed on the robot do not interfere with the inner wall of the work area or the inner wall of the stage, even if the robot moves to the operation switching point of the stage corresponding to the standby position by PTP operation.

According to the control method of the present invention, a motion switching point is set at a position where a part of the robot or a part of the workpiece is inside the stage , the robot is moved by PTP motion between the standby position and the motion switching point, and the robot is moved by linear interpolation motion between the motion switching point and the stage position, so that the moving distance by linear interpolation motion is shorter than that of the conventional control method, and the time required to transport the workpiece can be shortened. Also, since there is no need to fold the arms of the robot when moving between the standby position of one stage and the standby position of another stage, the transport time can be shortened.

In the control method of the present invention, it is preferable to move the robot between waiting positions using PTP operations. By moving the robot using PTP operations in this manner, it is possible to further reduce the transport time.

In the control method of the present invention, the robot is, for example, a horizontal articulated robot including a base, a base-side link rotatably connected to the base, an arm-side link connected to the base-side link, an arm rotatably connected to the arm-side link, and a hand rotatably connected to the arm to hold a workpiece. In this horizontal articulated robot, the base-side link and the arm-side link form a link mechanism that regulates the movement trajectory of the center point of the connecting axis between the arm-side link and the arm so that it becomes a predetermined straight line. By applying the present invention to control the horizontal articulated robot in a workpiece transport system including a horizontal articulated robot whose horizontal movement is greater than its vertical movement, it is possible to further shorten the transport time when the robot turns, and to significantly shorten the overall transport time.

According to the present invention, the time required to transport the workpiece can be reduced compared to when the standby/escape position is set on the axis of access to the stage but outside the stage.

1 is a schematic plan view showing a workpiece transport system according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view of a horizontal articulated robot. FIG. 2 is a diagram illustrating a method for controlling a robot according to the present invention. 1A to 1C are diagrams showing the steps of transporting a workpiece using a conventional control method. 1A to 1C are diagrams showing the steps of transporting a workpiece using a control method according to the present invention. FIG. 11 is a diagram showing the positions of the workpiece and the hand over time, comparing the case where a conventional control method and the case where a control method based on the present invention are implemented.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a workpiece transport system according to an embodiment of the present invention. This workpiece transport system is composed of a robot 1, which is an articulated robot, arranged in a working area 40, and a plurality of stages 20 arranged in contact with the working area 40 and on which a workpiece 21 is loaded and unloaded. The workpiece 21 is, for example, a semiconductor wafer. Here, five stages 20 are provided, but the number of stages 20 provided is not limited to this. The workpiece 21 has already been stored in the stage 20 at the upper right in the figure. The working area 40 is a space in which the robot 1 can move its hand, arm, etc. without interfering with other objects. In the illustrated example, the working area 40 is rectangular, but the shape of the working area 40 is not limited to a rectangle, and may be a polygon with a larger number of vertices, a concave polygon, or a polygon with some curved sides. Each stage 20 has an opening facing the working area 40, and the hand of the robot 1 can enter the inside of the stage 20 through this opening to load and unload a workpiece 21 onto the stage 20. The articulated robot 1 can transport the workpiece 21 between the stages 20 by moving its links, arms and hands.

The robot 1 is a three-link horizontal articulated robot similar to that described in Patent Document 2, and includes two hands 7a, 7b that hold a workpiece 21, an arm 6 that rotatably holds the hands 7a, 7b, a link mechanism 3 that rotatably holds an arm joint J1 at the base end of the arm 6 and operates so that the movement trajectory of the arm joint J1 is a straight line substantially parallel to the arrangement direction of the stages 20, and a base 2 on which the base end of the link mechanism 3 is rotatably supported. The link mechanism 3 is located on the base 2 side and includes a base side link 4 rotatably held on the base 2, and an arm side link 5 located on the arm 6 side, and both links 4, 5 are rotatably connected to each other by the link joint J2.

Figure 2 shows the robot 1, which is a horizontally articulated robot, in more detail, and is drawn as a vertical cross-section with the links 4, 5, arm 6, and hands 7a, 7b extended. The base 2 is equipped with a lifting tube 8 that is driven by a lifting motor (not shown) to move up and down. The base side link 4 is connected to the lifting tube 8 and rotatably held by a link mechanism motor 8a built into the lifting tube 8, and can move up and down relative to the base 2 as the lifting tube 8 moves up and down. The base side link 4 has a base side pulley 4a, an arm side pulley 4b, and a belt 4c built in, and the belt 4c is stretched between the base side pulley 4a and the arm side pulley 4b. The diameter ratio of the base side pulley 4a to the arm side pulley 4b is 2:1. The arm-side pulley 4b is connected to the arm-side link 5, and when the base-side link 4 rotates around the center of rotation of the base-side pulley 4a, the rotation angle ratio between the base-side pulley 4a and the arm-side pulley 4b, i.e., the rotation angle ratio between the base-side link 4 and the arm-side link 5, is 1:2. Furthermore, the base-side link 4 and the arm-side link 5 are equal in length. As a result, in the link mechanism 3, the movement trajectory of the center point (arm joint J1) of the connecting shaft that rotatably connects the arm-side link 5 and the arm 6 is restricted to a predetermined straight line.

The arm 6 is connected to the tip of the arm-side link 5 and is rotatably held by an arm drive motor 51 built into the arm-side link 5. In FIG. 2, the arm drive motor 51 is built into the arm-side link 5 for convenience of explanation, but the installation location of the arm drive motor 51 is not limited thereto. For example, the arm drive motor 51 may be built into the arm 6. The hands 7a and 7b are connected to the tip of the arm 6 and are rotatably held by frame motors 6a and 6b built into the arm 6. The connection centers of the hands 7a and 7b to the arm 6 are the same axis, and this axis is the rotation center J3 of the hands 7a and 7b. The hand 7a is disposed above the hand 7b. The robot 1 is provided with a robot controller 10 for driving the robot 1 and controlling its operation, and a teaching pendant 15 is connected to the robot controller 10 via a cable 16. The teaching pendant 15 is used by an operator when teaching the robot 1.

The robot 1 also has an origin position determined for its posture. In the robot 1 of this embodiment, the origin position is the state in which the base side link 4, arm side ring 5, arm 6, and hands 7a, 7b are folded so as to overlap each other, and the tips of the hands 7a, 7b are facing upward in FIG. 1.

In the method described in Patent Document 2, a standby/retract position for the stage 20 is set at a position in front of the stage 20 in the working area 40, and a linear interpolation operation is performed when the hand is moved from the standby/retract position to the inside of the stage 20. The standby/retract position is outside the stage 20 and on the axis of access to the stage 20. A linear interpolation operation is also performed when the hand is returned from the inside of the stage 20 to the standby/retract position. In contrast, in the work transport system of this embodiment, a position that is located within the working area 40 but does not necessarily have to be on the axis of access to the stage 20 is set as the standby position. Instead of locating the standby/retract position on the axis of access to the stage 20, a position on the axis where the hand is pulled back a certain distance from the stage 20 toward the working area 40 is set as the operation switching point. The operation switching point is generally located closer to the stage 20 than the standby position in Patent Document 2. Therefore, generally, when the hand is at the operation switching point, a part of the hand or the work is inside the stage 20.

In this embodiment, the "standby position" is the posture position where the arm is pulled back after the workpiece has been acquired or stored, or the position reached by a command to move the arm to the front position of the stage 20, which satisfies the following two conditions:
Condition 1: Even if the robot 1 is advanced by PTP motion from the standby position to the motion switching point of the stage 20, it does not interfere with the inner wall of the working area or the inner wall of the stage.
Condition 2: Even if the stage 20 rotates directly relative to the standby position of the other stage 20, the hand and the workpiece carried on the hand do not interfere with the inner wall of the working area 40, etc.

The standby position that satisfies the above conditions in the present invention can be determined in the same manner as the designated via point described in Patent Document 2, for example. When the posture in which the hand or arm is folded is the origin position of the robot 1, the robot 1 can also move between the origin position and the standby position by PTP operation. In this embodiment, the fixed position of the workpiece 21 is determined on the stage 20, and the position where the workpiece mounting part of the hand of the robot 1 coincides with the fixed position of the workpiece 21 on the stage 20 is called the "stage position". Therefore, "teaching the stage position" means registering the posture in which the center of the workpiece mounting part of the hand coincides with the center position of the workpiece 21 placed on the stage 20 as a coordinate. The loading and unloading of the workpiece 21 is performed at the stage position. In the transportation of the workpiece 21, vertical movement such as scooping up the workpiece 21 is also required, but since the present invention aims to shorten the transportation time in the horizontal direction, the following description of the vertical movement of the robot 1 is omitted.

Next, the control method in the work transport system of this embodiment will be described. In this embodiment, the work can be moved directly between the standby position of one stage 20 and the standby position of another stage 20 by PTP operation. At this time, since there is no need to fold the link mechanism or arm of the robot 1, the transport time can be shortened. In this embodiment, the transport time of the work between the standby position and the stage position is greatly shortened, thereby further shortening the overall transport time. FIG. 3 is a diagram explaining the control method in this embodiment. In FIG. 3 and the figures following it, the solid arrows indicate movement by PTP operation, and the dashed arrows indicate movement by linear interpolation operation. In this embodiment, the hand is moved between the standby position and the operation switching point by PTP operation that enables the fastest movement, and the hand is moved between the operation switching point and the stage position by linear interpolation operation. The operation switching point is a position through which the hand passes, and is set so that the amount of movement, i.e., the distance, in the linear interpolation operation is as short as possible under the condition that the hand and the work do not interfere with the inner wall of the stage 20. Such an operation switching point is set at a position closer to the stage position than the standby/retraction position in the method shown in Patent Document 2, so according to this embodiment, the movement distance by linear interpolation operation is shorter, and the overall movement time of the hand, i.e., the transport time, is shortened. Below, we will explain the operation according to the conventional control method and the operation according to this embodiment in detail by comparing them.

In the work transport system shown in FIG. 1, consider the case where the upper hand 7a of the robot 1 is used to transport the work 21 stored in the upper right stage 20 to the lower left stage 20. FIG. 4 shows the steps of the movement of the robot 1 and the work 21 in a conventional control method. (a) shows the robot 1 at the origin position. As shown in (b), the robot 1 moves from the origin position to the standby/retraction position of the upper right stage 20 by PTP operation. This standby/retraction position is on the axis of access to the stage 20. Next, as shown in (c), the hand 7a is moved to the stage position by linear interpolation operation to obtain the work 21. After obtaining the work 21, the hand 7a is pulled back to the standby/retraction position by linear interpolation operation as shown in (d), and then the robot 1 moves by PTP operation to the intermediate position before turning, which is a posture position in which the hand 7a is folded to a certain extent as shown in (e) so that the hand 7a and the work 21 do not interfere with the inner wall of the working area 40 when the arm is turned. Then, while rotating using PTP operation, the robot 1 moves to an intermediate position after rotation, in which the hand 7a is somewhat folded, as shown in (f). The intermediate positions shown in (e) and (f) are, for example, designated waypoints in the control method shown in Patent Document 2. From the intermediate position shown in (f), the robot 1 moves by PTP operation to a standby/retraction position on the lower left stage 20, as shown in (g). Finally, the hand 7a of the robot 1 moves by linear interpolation operation to the stage position on the lower left stage 20, and stores the workpiece 21 on the stage 20.

Figure 5 shows the movement of the robot 1 and the workpiece 21 when the transport of the workpiece 21 shown in Figure 4 is performed by the control method of this embodiment. Even in the control method of this embodiment, the robot 1 moves from the origin position shown in (a) to the standby position for the stage 20 at the upper right by PTP operation as shown in (b). The standby position here is not in front of the stage 20, and the hand 7a is also in a folded state compared to the case shown in Figure 5. Then, as shown in (c), the hand 7a moves to the operation switching point by PTP operation, and then moves to the stage position by linear interpolation operation as shown in (d) to acquire the workpiece 21. After acquiring the workpiece 21, the hand 7a returns to the operation switching point by linear interpolation operation as shown in (e), and then returns to the standby position shown in (f) by PTP operation. Next, the robot 1 rotates to the standby position of the stage 20 at the lower left by PTP operation as shown in (g). The standby position of the stage 20 at the lower left is also not in front of the stage 20, and the hand 7a is also in a folded state. From the standby position shown in (g), the hand 7a moves to the operation switching point by PTP operation as shown in (h), and then moves to the stage position by linear interpolation operation as shown in (i) to store the workpiece 21 on the stage 20. After that, the hand 7a moves to the operation switching point by linear interpolation operation as shown in (j), and returns to the standby position by PTP operation as shown in (k) for the next transfer.

Figure 6 shows the movement of the hand 7a and the workpiece 21 when the robot 1, which is at the origin position with the workpiece 21 placed thereon, stores the workpiece 21 on the stage 20, in a comparison between the conventional method (left side of the dashed line) and the method of this embodiment (right side of the dashed line). In the figure, the workpiece 21 is shown as a large circle, and the rotation axis J3, which is the connection center of the hand 7a to the arm 6, is shown as a small circle. The hand 7a itself is represented by showing its center line as a line segment. Time passes in order from (a) to (i), which show the origin position. In both control methods, the hand 7a moves from the origin position by PTP operation. In the control method of this embodiment, the hand 7a has already passed the standby position at (c), and part of the workpiece 21 has already entered the stage 20 at (e). At the point (f), the conventional control method finally reaches the standby/retraction position, whereas the method of this embodiment reaches the operation switching point. After that, in both control methods, the hand 7a moves toward the stage position by linear interpolation, but in the case of this embodiment, the hand 7a reaches the stage position at (h), whereas in the conventional control method, the hand 1 reaches the stage position at (i). Thus, with the control method of this embodiment, the stage position can be reached early, shortening the transport time.

In the workpiece transport system of this embodiment, the waiting position, operation via point, and stage position for each stage 20 may be registered in the robot controller 10 by teaching using the teaching pendant 15, for example, or may be calculated from the shape of the working area 40, the positional relationship of each stage 20 to the working area 40, and the dimensions of the link mechanism 3, arm 6, and hands 7a and 7b in the robot 1, and registered in the robot controller 40.

According to the workpiece transport system of this embodiment described above, an operational via point is set at a position where part of the hand or part of the workpiece is inside the stage 20, the robot is moved between the standby position and the operational switching point by PTP operation, and the robot is moved between the operational via point and the stage position by linear interpolation operation, so that the movement distance in the linear interpolation operation is shorter than when the robot is operated by the conventional control method, and the time required to transport the workpiece can be shortened. In addition, direct movement between the standby position of one stage and the standby position of another stage can be performed by PTP operation, and there is no need to fold the link mechanism or arms in the robot 1, which also shortens the transport time.

1... Articulated robot; 2... Base; 3... Link mechanism; 4... Base side link; 5... Arm part side link; 6... Arm; 7a, 7b... Hand; 8... Lifting tube; 10... Robot controller; 15... Teaching pendant; 20... Stage; 21... Workpiece; 40... Working area.

Claims (6)

A workpiece transport system having a working area, a plurality of stages arranged in contact with the working area, and a robot provided in the working area for loading/unloading a workpiece to/from the plurality of stages and transporting the workpiece,
A standby position and an operation switching point are defined for each stage,
the operation switching point is a position where the stage is pulled back from a stage position toward the working area, and where a part of the robot or a part of a workpiece placed on the robot is inside the stage when the robot is at the operation switching point;
the standby position is a position within the working area where the robot can turn directly relative to a standby position of another stage without interfering with an inner wall of the working area, and where the robot and the workpiece placed on the robot do not interfere with the inner wall of the working area or the inner wall of the stage even when the robot moves by point-to-point operation to the operation switching point of the stage corresponding to the standby position,
A workpiece transport system, wherein for each stage, the robot moves in a point-to-point manner between the waiting position and the operation switching point of the stage, and the robot moves in a linear interpolation manner between the operation switching point of the stage and the stage position. The workpiece transport system according to claim 1, wherein the robot moves between the waiting positions in a point-to-point manner. The robot comprises:
The base and
A base side link rotatably connected to the base;
an arm-side link connected to the base-side link;
an arm rotatably connected to the arm-side link;
a hand rotatably connected to the arm to hold the workpiece;
A horizontal articulated robot comprising:
3. The work transport system according to claim 1, wherein the base side link and the arm side link form a link mechanism that regulates a movement trajectory of a center point of a connecting shaft between the arm side link and the arm so that the movement trajectory is a predetermined straight line. A method for controlling a robot in a work transport system having a working area, a plurality of stages arranged in contact with the working area, and a robot provided in the working area for loading/unloading a work to/from the plurality of stages and transporting the work, comprising the steps of:
A standby position and an operation switching point are defined for each stage;
When moving the robot between the standby position and a stage position of the stage for each stage, the robot is moved between the standby position and the operation switching point of the stage by a point-to-point operation, and the robot is moved between the operation switching point and the stage position of the stage by a linear interpolation operation;
the operation switching point is a position of the stage pulled back from the stage position toward the working area, and a part of the robot or a part of the workpiece placed on the robot is inside the stage when the robot is at the operation switching point;
The waiting position is a position within the working area where the robot can rotate directly relative to a waiting position of another stage without interfering with the inner wall of the working area, and where the robot and the workpiece placed on the robot do not interfere with the inner wall of the working area or the inner wall of the stage even when the robot moves in a point-to-point operation to the operation switching point of the stage corresponding to the waiting position. The control method according to claim 4, wherein the robot is moved between the waiting positions in a point-to-point motion. The robot comprises:
The base and
A base side link rotatably connected to the base;
an arm-side link connected to the base-side link;
an arm rotatably connected to the arm-side link;
a hand rotatably connected to the arm to hold the workpiece;
A horizontal articulated robot comprising:
6. The control method according to claim 4, wherein the base side link and the arm side link form a link mechanism that regulates a movement trajectory of a center point of a connecting shaft between the arm side link and the arm so as to be a predetermined straight line.

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