Robot control method and control device

Abstract

In robots, when performing continuous movement actions, the total time required for a series of movement actions is reduced without being constrained by factors such as acceleration. [Solution] When a robot is given an action command to perform action A, action B following action A, and action C following action B, action C is started when action A enters and ends in a deceleration section, or immediately before it ends. Furthermore, action B is executed in conjunction with at least one of action A and action C, such that action B starts after the start of the deceleration section of action A and ends before the end of the acceleration section of action C.

Description

Technical Field

[0001] The present invention relates to the control of an industrial robot (hereinafter referred to as a robot) suitable for transporting a workpiece, and particularly to a control method and a control device capable of operating the robot at high speed.

Background Art

[0002] In the manufacture of liquid crystal display panels and organic EL (electroluminescence) display panels, it is necessary to transport a workpiece, i.e., a glass substrate, between process chambers that perform respective processes on the glass substrate via a transfer chamber (transport chamber). Since each process chamber is generally maintained under reduced pressure conditions or vacuum conditions, it is preferable to transport the workpiece in a reduced pressure state or a vacuum state when transporting the workpiece between the process chambers.

[0003] An example of a robot for transportation used for such a purpose is disclosed in Patent Document 1. The robot described in Patent Document 1 is disposed in the transfer chamber when a plurality of process chambers are arranged so as to surround the transfer chamber. And this robot is a horizontal articulated robot, and includes a base fixed to the floor surface of the transfer chamber, a lifting mechanism that moves up and down with respect to the base, a first arm having one end attached to the lifting mechanism so as to be rotatable in a horizontal plane, a second arm having one end attached to the other end of the first arm so as to be rotatable in a horizontal plane, and a hand capable of holding a workpiece to be transported. The hand is an elongated member and can hold the workpiece at each of its both ends, and is attached to the other end of the second arm at the central portion in the longitudinal direction so as to be rotatable in a horizontal plane. In this robot, the hand can be swung in a horizontal plane by rotating the first arm with respect to the lifting mechanism or by rotating the hand with respect to the second arm.

[0004] Each process chamber is equipped with an inlet / outlet that opens toward the transfer chamber. When loading a workpiece into or unloading a workpiece from a process chamber using the robot described in Patent Document 1, the hand is first moved to a position facing the inlet / outlet of the process chamber so that its longitudinal direction is perpendicular to the inlet / outlet. This position is called the access position. The access position is also called the "front position" relative to the process chamber. By moving the hand positioned at the access position along its longitudinal direction so that the end of the hand enters the process chamber, the workpiece held by the end of the hand can be loaded into the process chamber, and the workpiece inside the process chamber can be unloaded while being held by the end of the hand. The movement of moving the end of the hand from the access position into the process chamber is called the forward movement, and the movement of moving the end of the hand from inside the process chamber back to the access position is called the backward movement. Both the forward and backward movements are classified as linear movements in which the hand is moved along a constant direction while maintaining the orientation of the hand in that constant direction. When performing forward and backward movements relative to the access chamber, the hand moves along a reference straight line, ensuring that the longitudinal centerline of the hand coincides with this line. This straight line is called the access reference line. The access reference line is defined for each process chamber and is a straight line perpendicular to the discharge entrance of that process chamber and passing through the access position of that process chamber.

[0005] When transferring workpieces between process chambers, the orientation of the access reference line differs for each chamber. Therefore, a rotational movement is necessary to change the orientation of the hand within the transfer chamber. Because the transfer chamber is a narrow space, the rotational movement is performed with the arm folded and the center of rotation in the rotational movement aligned with the longitudinal centerline of the hand to prevent collisions between the hand, arm, workpiece, etc., with the walls of the transfer chamber. When transferring workpieces, after the rotational movement is completed, a forward movement is performed to bring the hand into the target process chamber. However, if the access reference line of the process chamber does not pass through the center of rotation of the hand's rotational movement, the hand must be rotated so that its longitudinal direction is parallel to the access reference line. Then, while maintaining the longitudinal orientation of the hand, it must be moved laterally so that it aligns with the access reference line of the destination process chamber. This movement is called a lateral movement. After performing the lateral movement to move the hand to the access position of the target process chamber, the forward movement of the hand is performed.

[0006] Ultimately, when transporting a workpiece using the robot described in Patent Document 1, the robot will either perform a forward movement following a rotational movement, or a lateral movement following a rotational movement, followed by a forward movement. When transporting a workpiece using a transport robot in this way, multiple movement actions are usually performed sequentially by the robot. Each movement action involves the robot accelerating from its starting point and moving, and then decelerating and stopping at its end point. When a robot performs two movement actions sequentially, if the robot stops at the end point of the first movement action (i.e., the starting point of the second movement action), the total time required for the two movement actions becomes longer. To shorten the required time, it is known that instead of stopping the robot between different movement actions, an overlapping action can be performed, as shown in Patent Document 2, in which the second movement action starts before the first movement action reaches its end point. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2015-139854 [Patent Document 2] Japanese Patent Publication No. 2022-57452 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] When a robot performs multiple movement actions in succession, overlapping movements between them can shorten the time from the start of the first movement to the end of the last movement. However, when using the horizontal articulated robot described in Patent Document 1 to transport workpieces between process chambers, the distance traveled in lateral movement is relatively small, but the acceleration and deceleration are large. If such lateral movement is overlapped with a rotational or linear movement, especially when overlapped with a rotational movement, the acceleration during the movement becomes larger, which may cause the workpiece placed on the robot's hand to shift position. Therefore, it has been difficult to shorten the overall travel time through overlapping. The inability to perform such consecutive movement actions by overlapping due to constraints such as acceleration is a phenomenon that can occur not only with the horizontal articulated robot shown in Patent Document 1, but with robots in general.

[0009] The object of the present invention is to provide a control method and a control device that can shorten the time required for a series of movement actions in a robot without being constrained by acceleration or other factors when performing movement actions in a series of actions. [Means for solving the problem]

[0010] According to one embodiment, a control method for controlling the movement of a robot in response to an action command causes the robot to perform a first movement, a second movement following the first movement, and a third movement following the second movement, and the control method is such that the third movement is started when the first movement enters and ends in a deceleration section or immediately before, and the second movement is started after the start of the deceleration section of the first movement and ends before the end of the acceleration section of the third movement, so that the second movement is performed in superimposition with at least one of the first movement and the third movement.

[0011] According to one embodiment, a control device for controlling a robot equipped with motors on each axis comprises a control unit that generates commands including speed for each motor in response to an operation command input from an external source, and a drive circuit that drives each motor based on the commands including speed. When the operation command causes the robot to perform a first movement, a second movement following the first movement, and a third movement following the second movement, the control unit generates commands including speed such that the third movement starts when the first movement enters and ends in a deceleration section, or immediately before it ends, and the second movement starts after the start of the deceleration section of the first movement and ends before the end of the acceleration section of the third movement, so that the second movement is executed in superimposed on at least one of the first and third movement. [Effects of the Invention]

[0012] According to the present invention, when a robot performs a series of movement actions, the time required for the entire series of movement actions can be reduced without being constrained by factors such as acceleration. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows a robot to which one form of control method is applied, where (a) is a top view and (b) is a front view. [Figure 2]This is a plan view illustrating the robot installed inside the transfer chamber. [Figure 3] This is a plan view showing the movement of the arm and hand. [Figure 4] (a) to (c) are plan views showing the movement of the arm and hand when the movement actions are superimposed. [Figure 5] (a) and (b) are graphs illustrating overlapping behavior. [Figure 6] This diagram illustrates the definitions of rotation angles and hand coordinates for each axis. [Figure 7] (a) to (c) are graphs showing the changes in angular velocity of each axis and the coordinates of the hand during overlapping motion. [Figure 8] (a) to (c) are graphs showing the change in hand acceleration during overlapping motion. [Modes for carrying out the invention]

[0014] Next, embodiments for carrying out the present invention will be described. Since the present invention relates to robot control, first, a robot to which a control method of one embodiment of the present invention can be applied will be described. Figure 1 shows an example of such a robot, where (a) is a plan view and (b) is a front view.

[0015] The robot 10 shown in Figure 1 is configured as a horizontal articulated robot for transporting plate-shaped workpieces such as glass substrates. It comprises a base 11 fixed to the floor surface where the robot 10 is installed, a lifting mechanism 12 driven by a motor (not shown) that moves up and down relative to the base 11 as indicated by arrows in the figure, a first arm 21 with one end rotatably connected to the upper surface of the lifting mechanism 12 and extending horizontally, a second arm 22 with one end rotatably connected to the other end of the first arm 21 and extending horizontally, and a hand 30 capable of holding the workpiece to be transported. The connection point between the lifting mechanism 12 and the first arm 21 is axis TH1, and by driving the first arm 21 with a motor (not shown), the first arm 21 can rotate in the horizontal plane around axis TH1. Similarly, the connection point between the first arm 21 and the second arm 22 is axis TH2, and by driving the second arm 22 with a motor (not shown), the second arm 22 can rotate in the horizontal plane around axis TH2.

[0016] The hand 30 is an elongated member as a whole, and includes a hand base 31 rotatably connected to the other end of the second arm 22, and four hand forks 32 which are linearly formed members. Two of the four hand forks 32 are arranged in parallel with a predetermined interval therebetween and are fixed to the hand base 31 so as to project from the hand base 31 in a first protruding direction in the horizontal plane. The remaining two hand forks 32 are fixed to the hand base 31 so as to project from the hand base 31 in a second protruding direction which is opposite to the first protruding direction in the horizontal plane. Therefore, the direction in which these hand forks 32 project and extend is the longitudinal direction of the hand 30, and the hand base 31 is arranged at the central portion in the longitudinal direction of the hand 30. At both ends of the hand 30, that is, at the tip portions of the respective hand forks 32, a plurality of support members 33 for holding a work are attached so as to extend in a direction orthogonal to the longitudinal direction of the hand 30. In the illustrated example, four support members 33 are provided at the tip portion of each hand fork 32 for each hand fork 32. Both ends in the longitudinal direction of the hand 30, that is, each position where the support members 33 are provided, is a position where a work to be conveyed is placed on the hand 30. The connection position between the second arm 22 and the hand base 31 is the axis S, and by driving the hand base 31 by the illustrated motor, the hand 30 can rotate around the axis S in the horizontal plane.

[0017] As shown in Figure 1(b), the robot 10 is connected to a control device 40 that receives motion commands from an external source and drives and controls the robot 10 based on these motion commands. Specifically, the control device 40 drives and controls the motors of each axis of the robot 10 (i.e., the motor that drives the lifting mechanism 12, and the motors that drive each of axes TH1, TH2, and S), and comprises a control unit 41 that receives motion commands from an external source, and a drive circuit 42 that includes servo drivers and the like to drive the motors of each axis. Since the robot 10 is used for transporting workpieces, the motion commands include commands for individual movement operations that move the hand 30. Based on the movement commands, the control unit 41 generates commands for each axis of the robot 10, including the speed of the motor for that axis, and the drive circuit 42 actually drives the motors of each axis of the robot 10 according to the commands for each axis. The drive circuit 42 and the robot 10 are electrically connected by a connecting cable 43.

[0018] The robot 10 shown in Figure 1 is installed, for example, in a transfer chamber for transporting workpieces between process chambers. Figure 2 shows the installation of the robot 10 in the transfer chamber 50. Here, an XY coordinate system is defined in the transfer chamber 50 as shown in the figure, and the robot 10 is installed so that axis TH1 is at the center of the transfer chamber 50. The transfer chamber 50 is surrounded by a plurality of process chambers (in the illustrated example, six process chambers 51A to 51F). In this example, the transfer chamber 50 has an octagonal shape with the four corners of a rectangle cut off. Process chamber 51A is provided on one of the pair of sides of this octagon that extend in the Y direction, and process chamber 51D is provided on the other side. Two process chambers 51B and 51C are provided on one of the pair of sides that extend in the X direction, and two process chambers 51E and 51F are provided on the other side.

[0019] Each of the process chambers 51A to 51F has a transfer opening 52 that opens toward the transfer chamber 50 for loading and unloading the workpiece W. The position facing the transfer opening 52 is the access position, and the straight line passing through the access position and orthogonal to the transfer opening 52 is the access reference line L. After moving the hand 30 of the robot 10 to the access position, the hand fork 32 of the hand 30 moves the hand 30 toward the transfer opening 52 along the access reference line L such that the longitudinal center line of the hand 30 overlaps with the access reference line L, so that it can enter the interiors of the process chambers 51A to 51F through the transfer opening 52. Therefore, the forward movement is a movement operation for entering the interior of the process chamber with the hand fork 32 from the access position, and the backward movement is a movement operation for retreating the hand fork 32 from the interior of the process chamber to the access position. In the example shown in FIG. 2, a pair of hand forks 32 holding the workpiece W has entered the interior of the process chamber 51A.

[0020] The turning operation of the hand 30 is performed in a state where the arms 21 and 22 are folded, that is, a state where the first arm 21 and the second arm 22 are folded over each other. By rotating the hand 30 around the axis S, a turning operation can be performed around the axis S. Further, when the effective length of the first arm 21, that is, the distance between the axis TH1 and the axis TH2, is equal to the effective length of the second arm 22, that is, the distance between the axis TH2 and the axis S, if the arms 21 and 22 are folded over each other, the axis TH1 and the axis S overlap, so that a turning operation can be performed around the axis S by rotating the first arm 21 around the axis TH1. In the following description, it is assumed that the effective length of the first arm 21 is equal to the effective length of the second arm 22.

[0021] When the rotational movement of the hand 30 is completed and the longitudinal centerline of the hand 30 coincides with the access reference line L of the process chambers 51A to 51F to be accessed, the hand can perform a forward movement immediately following the rotational movement. However, when the longitudinal centerline of the hand 30 and the access reference line L are parallel but separated, it is necessary to perform a lateral movement to move the hand 30 so that it coincides with the access reference line L while maintaining the longitudinal orientation of the hand. In the example shown in Figure 2, the access reference line L of the process chambers 51B, 51C, 51E, and 51F does not intersect with the axis TH1 of the robot 10, so when accessing these process chambers 51B, 51C, 51E, and 51F, it is necessary to perform a lateral movement immediately following the rotational movement.

[0022] Figure 3 is a plan view illustrating the movement of arms 21, 22 and hand 30 when performing a series of movement actions consisting of rotation, lateral movement, and forward movement. In Figure 3 (a), the initial state before starting the rotation action is shown. Here, arms 21 and 22 are folded. When the second arm 22 is overlapping the first arm 21, only the second arm 22 is shown in the figure. In this state, hand 30 does not overlap with arms 21 and 22. During the rotation action, hand 30 is rotated around axis TH1 of the robot 10, and hand 30 is rotated around axis S relative to arm 21 and 22. Specifically, during the rotation action, the first arm 21 is rotated +45° relative to the base 11 around axis TH1, and hand 30 is rotated 90° relative to the second arm 22 around axis S, so that the longitudinal direction of hand 30 faces the Y direction and the first arm 21 also extends from axis TH1 in the +Y direction. (b) shows the state after the turning motion has been completed.

[0023] After the rotational movement is complete, a lateral movement is performed to move the hand 30 in a direction perpendicular to its longitudinal direction, while maintaining the longitudinal orientation of the hand 30. In the illustrated example, the hand 30 is moved in the -X direction. During the lateral movement, all axes TH1, TH2, and S of the robot 10 are driven. In Figure 3, (c) shows the state after the lateral movement has been completed. After the lateral movement is completed, a forward movement is performed to move the hand 30 in the +Y direction while maintaining its orientation. During the forward movement, all axes TH1, TH2, and S of the robot 10 are also driven. The series of movements is completed when the forward movement is completed. (d) shows the completed state, i.e., the state after the forward movement has been completed. By performing the series of movements described here in reverse, the robot can be moved from the state shown in (d) to the state shown in (a) in Figure 3. In this case, the series of movements are performed in the order of backward movement, lateral movement, and rotational movement.

[0024] Figures 4(a) to 4(c) illustrate the movements of arms 21, 22 and hand 30 when the above-described movement actions are superimposed. Figure 4(a) shows the case where the rotational movement and the lateral movement are superimposed, and the arrows shown in thick lines in the figure indicate the movement of hand 30 at this time. Similarly, Figure 4(b) shows the case where the lateral movement and the forward movement are combined, and the arrows shown in thick lines indicate the movement of hand 30. Figure 4(c) shows the case where the rotational movement, the lateral movement, and the forward movement are superimposed. However, in the example shown in Figure 4(c), the rotational movement and the lateral movement are superimposed in the first half of the lateral movement period, and the lateral movement and the forward movement are superimposed in the second half of the lateral movement period. The arrows shown in thick lines indicate the movement of hand 30 at this time, divided into the first half and the second half of the lateral movement period.

[0025] Figures 5(a) and 5(b) illustrate overlapping motion by describing the time change of the robot 10's speed. Here, we consider that movements A, B, and C, all of which are movement movements, are performed consecutively in this order, and Figures 5(a) and 5(b) show the speed of the robot 10 for each movement. When overlapping occurs between movement movements when controlling the horizontal articulated robot shown in Figures 1 to 3, movements A to C correspond to turning, lateral movement, and forward movement, respectively. Movement A is performed first when the robot 10 is stationary. In movement A, the robot 10 accelerates at a predetermined acceleration from the start, and once it reaches the predetermined speed, the robot 10 operates at a constant speed, and then decelerates at a predetermined deceleration until it finally stops. The period when the robot 10 is accelerating and the period when it is decelerating are called the acceleration section and the deceleration section, respectively, and the period when it is operating at a constant speed is called the constant speed section. Movement C is also composed of an acceleration section, a constant speed section, and a deceleration section, similar to movement A. However, because the axes driven in robot 10 are different, the acceleration, deceleration, and speed in the constant-velocity section differ between operation A and operation C. In contrast, operation B, for example, which is a lateral movement, does not have a constant-velocity section and is composed of an acceleration section and a deceleration section, due to the short distance traveled. Since it is desirable to complete all movement operations as quickly as possible, the acceleration in the acceleration section and the deceleration in the deceleration section are set to be as large as possible. The speed in the constant-velocity section is also set to the maximum achievable speed determined by the robot's maximum rated values, etc.

[0026] In Figure 5(a), operation B begins just before operation A finishes in the deceleration section. That is, operation A and operation B overlap. Furthermore, operation C begins just before operation B finishes in the deceleration section. That is, operation B and operation C also overlap. In the figure, arrow p indicates the section in which the overlapping operations are performed. The ratio of the amount of movement (i.e., the amount of movement) in operation B during the period in which it overlaps with operation A or operation C (i.e., the section indicated by arrow p) is called the overlap rate. In the example shown in Figure 5(a), the overlap rate is about 20%. When performing two consecutive movement operations with overlap, the amount to set the overlap rate is determined by considering the precision of the movement operations and the acceleration generated during the movement in the overlapping operation. If operation A here is the turning operation described above and operation B is a lateral movement operation, there is a risk that the acceleration will be large when the turning operation and the lateral movement operation are performed in superimposition, so it may not be possible to increase the overlap rate. If the overlap rate cannot be increased, it will be difficult to shorten the overall time required for the series of movement operations.

[0027] Figure 5(b) shows the time change of the robot 10's speed when overlapping motion is applied to operations A to C, as described using Figure 5(a), by a control method according to one embodiment of the present invention. In Figure 5(b), operation C starts immediately after the end of operation A, and operations A and C are executed consecutively. Operation C may start immediately before the end of operation A, resulting in a slight overlap between operations A and C. Operation B, as indicated in Figure 5(b) as "Operation B (no adjustment)", starts after the deceleration section of operation A begins and ends before the acceleration section of operation C ends, and is executed in conjunction with at least one of operations A and C. By executing operations A to C in this way, the overall operation time can be shortened compared to the case shown in Figure 5(a). If operation C starts simultaneously with or before the end of operation A, the overall operation time is determined only by operations A and C, and the operation time of operation B itself does not affect the overall operation time. In this case, the overlap rate for operation B is 100%.

[0028] When operation B is executed independently based on an operation command, the acceleration in the acceleration section and the deceleration in the deceleration section are maximized to minimize the operation time of operation B. However, if operation C starts simultaneously with or before the end of operation A, the operation time of operation B itself does not affect the overall operation time, so the acceleration in the acceleration section and the deceleration in the deceleration section of operation B can be set to small values. The change in speed of operation B when the acceleration and deceleration are reduced is shown as "Operation B (Adjusted)" in Figure 5(b). When the degree of acceleration and deceleration is adjusted, the amount of movement (amount of displacement) in operation B must be the same, so compared to the case without adjustment, the start of operation B will be earlier and the end of operation B will be later. In the example shown in Figure 5(b), operation B starts at the start of the deceleration section of operation A, and operation B also ends at the end of the acceleration section of operation C. Also, the maximum speed during operation B is lower compared to the case without adjustment of the degree of acceleration and deceleration, as indicated by arrow q in the figure. By adjusting the acceleration and deceleration in this way, the acceleration during operation B can be reduced without changing the overall operation time, which in turn makes it less likely for the workpiece W to shift position during transport.

[0029] The following describes simulation examples of changes in the rotation angle of each axis, the velocity of the hand 30, and the acceleration when the control method of this embodiment is applied to the robot 10 shown in Figures 1 to 3. Figure 6 is a diagram illustrating the definition of the rotation angle of each axis and the coordinates of the hand. The coordinates of the hand 30 are defined with axis S as the origin, the direction toward the longitudinal direction of the hand 30 as the y-direction, and the direction perpendicular to the y-direction as the x-direction. The xy coordinate system here is a coordinate system attached to the hand 30 and is different from the XY coordinate system set in the transfer chamber 50. Figures 7(a) to 7(c) are graphs showing the changes in the rotation angle of each axis and the x-direction velocity and y-direction velocity of the hand 30. Figure 7(a) shows the case when the conventional overlapping motion method shown in Figure 5(a) is applied, and Figures 7(b) and 7(c) both show the case where motion B is superimposed on motions A and C as shown in Figure 5(b). Figure 7(b) shows the case where the acceleration / deceleration degree is not adjusted, and Figure 7(c) shows the case where the acceleration / deceleration degree is adjusted. Figures 8(a) to 8(c) are graphs showing the change in acceleration at hand 30. (a) shows the acceleration in the x-direction at hand 30, (b) shows the change in the y-direction, and (c) shows the acceleration obtained by combining the acceleration in the x-direction and the acceleration in the y-direction. In Figures 8(a) to 8(c), "Conventional" shows the change when the conventional overlapping motion method shown in Figure 5(a) is applied. "Increased OL amount (no adjustment)" shows the case where motion B is superimposed on motions A and C as shown in Figure 5(b), but no adjustment of the degree of acceleration or deceleration is made. "Increased OL amount (with adjustment)" shows the case where motion B is superimposed on motions A and C as shown in Figure 5(b), and the degree of acceleration or deceleration is adjusted.

[0030] Comparing the graphs shown in Figures 7(a) to 7(c), the overall operation time for the series of movements is shorter when using the control method of this embodiment (Figures 7(b) and 7(c)) compared to when using the conventional control method (Figure 7(a)), by the amount indicated by arrow r in the figures. Furthermore, comparing the speed of the hand 30, the maximum speed is lower in the x-direction of the hand 30 when the acceleration / deceleration is adjusted (Figure 7(c)) compared to when the acceleration / deceleration is not adjusted (Figure 7(b)).

[0031] Comparing the graphs shown in Figures 8(a) to 8(c), in the overlap operation using the control method of this embodiment without adjusting the degree of acceleration and deceleration, there are periods in which the absolute value of the acceleration in the x-direction and the composite acceleration of the hand 30 are considerably larger than in the conventional overlap operation, as shown by figure s. In contrast, when the degree of acceleration and deceleration is adjusted, the increase in the absolute value of the acceleration in the x-direction and the composite acceleration can be suppressed compared to when the degree of acceleration and deceleration is not adjusted. Thus, it can be seen that by adjusting the degree of acceleration and deceleration during movement, the increase in the acceleration actually experienced by the hand 30 and workpiece W can be suppressed while shortening the overall operation time.

[0032] The control of the robot 10 in this embodiment has been described above. As described above, the control that performs overlapping operations is realized when the control unit 41 analyzes the operation command input from the outside in the control device and generates a command including the speed for each axis of the robot 10, and the drive circuit 42 actually drives the motor of each axis of the robot 10 according to the command for each axis. Specifically, when an operation command is input that includes performing operation A, then operation B after operation A, and then operation C after operation B, the control unit 41 generates commands for each axis of the robot 10 so that operations A to C are executed in overlapping order with the speed changes shown in Figure 5(b).

[0033] According to the control method of this embodiment described above, when the first movement operation A, the second movement operation B, and the third movement operation C are executed in succession, it is possible to prevent excessive acceleration from being applied to the robot's hand 30 or the workpiece W held by the hand 30, while also shortening the overall operation time of the series of movement operations.

[0034] The control method of this embodiment is not limited to horizontal articulated robots used for transporting workpieces W, but can also be applied to robots of other forms or for other purposes. Furthermore, although the second movement operation, operation B, is described above assuming that there is no constant velocity section, the second movement operation may also have a constant velocity section. The first and third movement operations may not include a constant velocity section.

[0035] The above describes an example of a configuration for carrying out the present invention, but the above technology can take the following configuration.

[0036] (1) A control method for controlling the movement of a robot in accordance with an action command, When the aforementioned motion command causes the robot to perform a first movement, a second movement following the first movement, and a third movement following the second movement, When the first movement operation enters and ends in the deceleration section, or immediately before it ends, the third movement operation is started. A control method in which the second movement is performed in superimposition with at least one of the first movement and the third movement, such that the second movement starts after the start of the constant-velocity section of the first movement and ends before the end of the constant-velocity section of the third movement.

[0037] (2) The control method according to (1), wherein the second movement is performed in superimposition with at least one of the first movement and the third movement, such that the second movement starts after the start of the deceleration section of the first movement and the second movement ends before the end of the acceleration section of the third movement.

[0038] (3) The control method according to (1) or (2), wherein when the second movement is performed in conjunction with at least one of the first movement and the third movement, the second movement is performed with acceleration and deceleration smaller than the acceleration and deceleration when the second movement is performed alone.

[0039] (4) The control method according to (3), wherein the second movement is started at the same time as the deceleration section of the first movement is started, and the second movement is terminated at the same time as the acceleration section of the third movement is ended.

[0040] (5) The robot has a first arm, one end of which is rotatable in a horizontal plane around a first axis; a second arm, one end of which is connected to the other end of the first arm via a second axis and is rotatable in a horizontal plane around the second axis; and a hand, the other end of the second arm via a third axis and is rotatable in a horizontal plane around the third axis. The first movement is either a rotational movement or a linear movement, the second movement is a lateral movement, and the third movement is the other of the rotational movement and the linear movement. The aforementioned rotational movement is a movement in which the hand is rotated around the third axis from a state in which the first arm and the second arm are folded together and the hand is facing a first direction in the horizontal plane, so that the orientation of the hand is a second direction different from the first direction. The aforementioned linear movement is a movement in which the hand moves along the second direction while remaining facing the second direction. The control method according to any one of (1)-(4), wherein the lateral movement is a movement that drives the first arm and the second arm to move the hand in a direction perpendicular to the second direction.

[0041] (6) A control device for controlling a robot equipped with a motor on each axis, A control unit that generates commands including the speed for each of the motors in response to an operation command input from an external source, A drive circuit that drives each of the motors based on a command including the speed, Equipped with, The control unit generates a command including speed such that, when the operation command causes the robot to perform a first movement, a second movement following the first movement, and a third movement following the second movement, the control unit causes the third movement to start when the first movement enters a deceleration section and ends, or immediately before it ends, and the second movement is performed in superimposed on at least one of the first movement and the third movement, such that the second movement starts after the start of the constant-velocity section of the first movement and ends before the end of the constant-velocity section of the third movement.

[0042] (7) The control method according to (6), wherein the control unit generates a command including the speed such that the second movement starts after the start of the deceleration section of the first movement and ends before the end of the acceleration section of the third movement.

[0043] (8) The control device according to (6) or (7), wherein the control unit generates a command including the speed such that when the second movement is performed in conjunction with at least one of the first movement and the third movement, the second movement is performed with acceleration and deceleration smaller than the acceleration and deceleration when the second movement is performed alone.

[0044] (9) The control device according to (8), wherein the control unit generates a command including the speed such that the second movement starts at the same time as the deceleration section of the first movement starts, and the second movement ends at the same time as the acceleration section of the third movement ends.

[0045] (10) The robot has a first arm, one end of which is rotatable in a horizontal plane around a first axis; a second arm, one end of which is connected to the other end of the first arm via a second axis and is rotatable in a horizontal plane around the second axis; and a hand, the other end of the second arm via a third axis and is rotatable in a horizontal plane around the third axis. The first movement is either a rotational movement or a linear movement, the second movement is a lateral movement, and the third movement is the other of the rotational movement and the linear movement. The aforementioned rotational movement is a movement in which the hand is rotated around the third axis from a state in which the first arm and the second arm are folded together and the hand is facing a first direction in the horizontal plane, so that the orientation of the hand is a second direction different from the first direction. The aforementioned linear movement is a movement in which the hand moves along the second direction while remaining facing the second direction. The control device according to any one of (6)-(9), wherein the lateral movement is a movement that drives the first arm and the second arm to move the hand in a direction perpendicular to the second direction.

[0046] According to the configurations shown in (1) and (6), the entire second movement is superimposed on at least one of the first movement and the third movement, thus allowing for a reduction in the overall execution time of the series of movement operations while better avoiding constraints such as acceleration. In particular, according to the configurations shown in (2) and (7), the entire second movement is superimposed on at least one of the deceleration section of the first movement and the acceleration section of the third movement, thus allowing for a reduction in the overall execution time of the series of movement operations while better avoiding constraints such as acceleration.

[0047] According to the configurations shown in (3) and (8), when the second movement is performed in conjunction with at least one of the first and third movement movements, a smaller acceleration is used than when the second movement is performed alone. Therefore, the increase in acceleration in the robot when multiple movement movements are performed in conjunction can be suppressed. In particular, by adopting the configurations shown in (4) and (9), the increase in acceleration can be minimized while shortening the overall operation time of the series of movement movements.

[0048] According to the configurations shown in (5) and (10), in a horizontal articulated robot used for transporting plate-shaped workpieces such as glass substrates, the time required for transporting the workpiece can be shortened, thereby reducing the cycle time. [Explanation of Symbols]

[0049] 10...Robot, 11...Base, 12...Lifting mechanism, 21...First arm, 22...Second arm, 30...Hand, 31...Hand base, 32...Hand fork, 33...Support member, 40...Control device, 41...Calculation unit, 42...Drive circuit, 43...Connecting cable, 50...Transfer chamber, 51A~51F...Process chamber, 52...Inlet / Outlet, L...Access reference line, W...Workpiece.

Claims

1. A control method for controlling the movement of a robot in accordance with an action command, When the aforementioned operation command causes the robot to perform a first movement, a second movement following the first movement, and a third movement following the second movement, When the first movement operation enters and ends in the deceleration section, or immediately before it ends, the third movement operation is started. A control method in which the second movement is executed in superimposition with at least one of the first movement and the third movement, such that the second movement starts after the start of the constant-velocity section of the first movement and ends before the end of the constant-velocity section of the third movement.

2. The control method according to claim 1, wherein the second movement is performed in superimposition with at least one of the first movement and the third movement, such that the second movement starts after the start of the deceleration section of the first movement and ends before the end of the acceleration section of the third movement.

3. The control method according to claim 1 or 2, wherein when the second movement is performed in conjunction with at least one of the first movement and the third movement, the second movement is performed with acceleration and deceleration smaller than those when the second movement is performed alone.

4. The control method according to claim 3, wherein the second movement operation is started simultaneously with the start of the deceleration section of the first movement operation, and the second movement operation is terminated simultaneously with the end of the acceleration section of the third movement operation.

5. The robot has a first arm, one end of which is rotatable in a horizontal plane around a first axis; a second arm, one end of which is connected to the other end of the first arm via a second axis and is rotatable in a horizontal plane around the second axis; and a hand, the other end of the second arm via a third axis and is rotatable in a horizontal plane around the third axis. The first movement is either a rotational movement or a linear movement, the second movement is a lateral movement, and the third movement is the other of the rotational movement and the linear movement. The aforementioned rotational movement is a movement in which the hand is rotated around the third axis from a state in which the first arm and the second arm are folded together and the hand is facing a first direction in the horizontal plane, so that the orientation of the hand is a second direction different from the first direction. The linear movement described above is a movement in which the hand moves along the second direction while remaining facing the second direction. The control method according to claim 1 or 2, wherein the lateral movement is a movement that drives the first arm and the second arm to move the hand in a direction perpendicular to the second direction.

6. A control device for controlling a robot equipped with a motor on each axis, A control unit that generates commands including the speed for each of the motors in response to an operation command input from an external source, A drive circuit that drives each of the motors based on a command including the speed, Equipped with, The control unit generates a command including speed such that, when the operation command causes the robot to perform a first movement, a second movement following the first movement, and a third movement following the second movement, the control unit causes the third movement to start when the first movement enters a deceleration section and ends, or immediately before it ends, and the second movement is performed in superimposed on at least one of the first movement and the third movement, such that the second movement starts after the start of the constant-velocity section of the first movement and ends before the end of the constant-velocity section of the third movement.

7. The control method according to claim 6, wherein the control unit generates a command including the speed such that the second movement starts after the start of the deceleration section of the first movement and ends before the end of the acceleration section of the third movement.

8. The control device according to claim 6 or 7, wherein the control unit generates a command including the speed such that when the second movement is performed in conjunction with at least one of the first movement and the third movement, the second movement is performed with acceleration and deceleration smaller than the acceleration and deceleration when the second movement is performed alone.

9. The control device according to claim 8, wherein the control unit generates a command including the speed such that the second movement starts simultaneously with the start of the deceleration section of the first movement and the second movement ends simultaneously with the end of the acceleration section of the third movement.

10. The robot has a first arm, one end of which is rotatable in a horizontal plane around a first axis; a second arm, one end of which is connected to the other end of the first arm via a second axis and is rotatable in a horizontal plane around the second axis; and a hand, the other end of the second arm via a third axis and is rotatable in a horizontal plane around the third axis. The first movement is either a rotational movement or a linear movement, the second movement is a lateral movement, and the third movement is the other of the rotational movement and the linear movement. The aforementioned rotational movement is a movement in which the hand is rotated around the third axis from a state in which the first arm and the second arm are folded together and the hand is facing a first direction in the horizontal plane, so that the orientation of the hand is a second direction different from the first direction. The linear movement described above is a movement in which the hand moves along the second direction while remaining facing the second direction. The control device according to claim 6 or 7, wherein the lateral movement is a movement that drives the first arm and the second arm to move the hand in a direction perpendicular to the second direction.

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