Conveying device

Abstract

To provide a conveying device which corrects a conveying trajectory according to a positional deviation without impairing trajectory characteristics generated offline when there is a positional deviation between an initial conveying position and a conveying position obtained through teaching.SOLUTION: A conveying device includes a trajectory correction unit that corrects a conveying trajectory Pt such that an end point E of the conveying trajectory Pt becomes a target end point E' when the target end point E' deviates from the end point E of the conveying trajectory Pt. When a deviation in the trajectory occurs in the middle of correction of the trajectory having a conveying start position as a start point and a conveying stop position as an end point, the trajectory correction unit sets an intermediate point M between the conveying start position TS and the conveying stop position TE, divides the trajectory into a first trajectory Pt1 having the conveying start position TS as a start point S and the intermediate point M as an end point E, and a second trajectory Pt2 having the intermediate point M as a start point S and the conveying stop position TE as an end point E, and performs trajectory correction.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a conveying device that conveys an object along a conveying track, and more particularly to a conveying device that optimizes the function of correcting the deviation between a preset conveying track and a target position. [Background technology]

[0002] Horizontal articulated robots that transport wafers often operate using a tip trajectory that is generated offline in advance to improve transport efficiency. The trajectory generated offline takes into account the dimensions of peripheral equipment (vacuum chambers), but in practice, work (teaching) is carried out to fine-tune the trajectory to account for external influences and assembly errors when assembling the robot to the chamber.

[0003] In this case, a positional deviation occurs between the stop position generated offline and the stop position adjusted by teaching. In actual operation, the transport operation must be performed based on the stop position adjusted by teaching, so the positional deviation must be taken into consideration.

[0004] One method, as shown in Patent Document 1 in Fig. 12(a), is to adjust the transfer trajectory of the wafer W generated offline without changing it, that is, to move the wafer W from the start position S to the stop position E obtained offline, and then move it to the taught stop position E'. However, this method may reduce the transfer efficiency and generate vibrations.

[0005] In light of this, Prior Art Document 2 proposes a method for correcting positional deviations without reducing conveyance efficiency or impairing the characteristics of the conveyance trajectory. As a specific example, we will explain a case where, for the offline trajectory Pt shown in Figure 13(a), the start position S is the same, but a positional deviation occurs between the stop position E determined offline and the stop position E' set by teaching. Of course, the same applies if the stop position E is the same and the start position S is shifted, or if both are shifted, as shown in Figure 14.

[0006] 13(a) and (b), the distances d1N and d2N (described later) from the start position S to the stop position E and the target stop position E' can be calculated. Since the position on the trajectory is expressed by the rotation angle of the joint axis, if the offline transfer start position is θ1, the offline transfer stop position is θN, and the teaching stop position is θN', the coefficient β is β=d2N / d1N=(θN´-θ1) / (θN-θ1) It can be expressed as:

[0007] Therefore, if the ratio of d1N to d2N (correction coefficient β) is corrected at each point Pk between the start position S(θ1) and the stop position E(θN), then: β=d2k / d1k=(θk´-θ1) / (θk-θ1) θk´=β(θk-θ1)+θ1 The trajectory Pt' connecting these points can be used as the corrected trajectory.

[0008] By performing the above-described correction, there is no need for separate movement at the start position S or the stop position E, and therefore no decrease in conveyance efficiency occurs. Furthermore, the change in speed and acceleration during operation due to position correction is also multiplied by the ratio of d1N and d2N as a coefficient, but the positional deviation L due to teaching is generally insignificant compared to the distance d1N between the start position and the stop position. Therefore, the correction coefficient becomes a value close to 1, and conveyance characteristics do not change significantly, as described in Patent Document 2 (paragraphs 0031 and 0032). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-145461 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-167828 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in reality, the distance d1N between the transfer start position S and the transfer stop position E may be very small. In addition, there is a possibility that the distance during movement may become excessively large, which may significantly impair the transfer track and transfer characteristics.

[0011] Let us take as an example the case where a robot is installed in a transfer chamber (vacuum chamber) whose interior is kept at a vacuum, as shown in Figure 15. The solid lines indicate the robot arms at the start / stop positions, and we consider the case where arms A1, A2, and hand H, which are in the first position, move to second positions A1', A2', and H'. The T axis indicates the shoulder joint, the R axis indicates the elbow joint, and the H axis indicates the wrist joint, and the dashed line indicates the trajectory of the wafer center.

[0012] Figure 16(a) shows the transfer trajectory of the wafer tip (center) using X and Y coordinates within the transfer chamber. The solid line represents the predetermined offline trajectory. The dashed line represents the movement locus of the wafer tip trajectory when the wafer tip transfer stop position is shifted 1 mm in the X direction and 1 mm in the Y direction on the XY coordinate system and the trajectory is corrected using the method described in Patent Document 2. Figures 16(b), 17(a), and 17(b) show graphs showing the operating angles of each axis over time. The solid and dashed lines correspond to the solid and dashed lines in Figure 16(a). As is clear from Figure 16(a), shifting the wafer tip by just 1 mm causes the tip trajectory to change significantly during operation. This results in a loss of the trajectory characteristics generated offline. Furthermore, when the tip coordinate system is converted into the joint coordinate system of each axis (T, R, H), comparing the trajectories before and after correction, it can be seen that the trajectories of the R-axis and H-axis shown in Figures 17(a) and (b) have hardly changed, whereas the trajectory of the T-axis shown in Figure 16(b) has changed significantly from the reference trajectory.

[0013] In other words, as the tip moves to the right from the starting position in Figure 15, the T-axis gradually rotates left (counterclockwise in the figure), causing the R-axis and H-axis to move away from the upper wall of the transport chamber (decreasing the Y coordinate), and after the R-axis and H-axis rotate right within the area, the R-axis is controlled to return to almost its original X- and Y-coordinate positions. Arms A1 and A2 and hand H, which were in the starting positions, have moved to A1', A2', and H' at the completion positions (there is almost no change in A1 and A1'). At this time, correction is made so that the movement of the T-axis follows a trajectory that significantly overshoots the offline trajectory.

[0014] The reason why only the T-axis deviates significantly from the original trajectory is that, compared to the R-axis and H-axis, the distance L between the start position and the stop position of the T-axis is minute, as shown in Figure 16(b), and this has a significant effect on the correction coefficient and the trajectory. The method for calculating the correction coefficient in Patent Document 2 will be described again.

[0015] <Expression 1> β=d2 N / d1 N =(θ' N -θ1) / (θ N -θ1) β: coefficient θ' N : Teaching stop position θ N : Offline stop position θ1: Starting position

[0016] In Equation 1, as shown in FIG. 16(b), the distance L(θ N If -θ1) is small, the denominator will be small. Therefore, even if the tip is misaligned by about 1 mm, the correction coefficient will be large.

[0017] The conventional correction method is to calculate the distance between the start position and the stop position (θ N -θ1) and the distance between the start position and the stop position after teaching (θ' N-θ1) is calculated as the correction coefficient β. For this reason, as shown in Figure 16(b), when the distance L between the start position and the stop position is minute (for example, 0.1 mm), even if the positional deviation L' (around 1 mm) of a typical teaching tip is minute, the correction coefficient β will be large (for example, about 10 times larger). In this state, if the distance L between the start position and the stop position is short and the amount of movement D along the way is large, the amount of movement D will be multiplied by the correction coefficient β, and as a result, a correction will be made so that the amount of movement D' along the way is larger than expected, as shown by the dashed line.

[0018] In view of these problems, the present invention aims to provide a transport device that, when a positional deviation occurs between the initial transport position and the transport position obtained by teaching in a wafer transport robot, corrects the transport trajectory in accordance with the positional deviation without impairing the trajectory characteristics generated offline. [Means for solving the problem]

[0019] In order to achieve the above object, the present invention takes the following measures.

[0020] That is, the conveying device of the present invention is The object to be conveyed is conveyed along a conveying track from a conveying start position to a conveying stop position, When carrying out conveyance control using a predetermined conveyance track from a certain start point to a certain end point, if a target end point is deviated from the end point of the conveyance track, a trajectory correction unit is provided which corrects the conveyance track so that the end point of the conveyance track becomes the target end point, the trajectory correction unit corrects the trajectory by expanding or contracting the pre-correction distance along the deviation direction using the starting point as a reference, so that the ratio between the pre-correction distance and the post-correction target distance is the same regardless of which of the predetermined points on the trajectory the certain point is located at, where the deviation direction is the direction connecting the pre-correction end point and the post-correction target end point, the pre-correction distance is the deviation direction component of the distance from the start point to a certain point on the pre-correction trajectory, and the corresponding point is a point on the post-correction trajectory that is located on an axis along the deviation direction and that passes through the certain point, the post-correction distance is the deviation direction component of the distance from the start point to the corresponding point, the trajectory correction unit sets one or more intermediate points between the transfer start position and the transfer stop position when a deviation of the trajectory occurs midway during correction of the trajectory having the transfer start position as a start point and the transfer stop position as an end point, The trajectory is corrected by dividing it into a trajectory having the transfer start position as the starting point and the midpoint as the end point, and a trajectory having the midpoint as the starting point and the transfer stop position as the end point.

[0021] In this way, a first trajectory correction is performed with the midpoint as the end point and the start position of the transfer trajectory, and the midpoint as the start point. Then, a second trajectory correction is performed with the midpoint as the next start point and the original transfer stop position as the next end point. This prevents the midpoint from deviating from the trajectory, achieving overall trajectory optimization. Even if the distance between the transfer start position and the transfer stop position is small, sufficient distance can be ensured between the transfer start position and the midpoint during the transfer, and between the midpoint and the transfer stop position. This prevents the correction coefficient from being excessively large, and prevents deviations from the trajectory around the midpoint. This makes it possible to appropriately correct the entire trajectory in response to positional deviations of the transfer stop position without compromising the trajectory characteristics obtained offline.

[0022] Alternatively, the conveying device of the present invention conveys an object to be conveyed along a conveying track from a conveying start position to a conveying stop position, When carrying out conveyance control using a predetermined conveyance track from a certain start point to a certain end point, if a target start point is deviated from the start point of the conveyance track, a trajectory correction unit is provided which corrects the conveyance track so that the start point of the conveyance track becomes the target start point, the trajectory correction unit corrects the trajectory by expanding or contracting the pre-correction distance along the deviation direction using the end point as a reference so that the ratio between the pre-correction distance and the post-correction distance is the same regardless of which of the predetermined points on the trajectory the certain point is located at, where the deviation direction is the direction connecting the pre-correction start point and the post-correction target start point, the pre-correction distance is the deviation direction component of the distance from a certain point on the pre-correction trajectory to the end point, and the corresponding point is a point on the post-correction trajectory that is located on an axis along the deviation direction and that passes through the certain point, the post-correction distance is the deviation direction component of the distance from the corresponding point on the post-correction trajectory to the end point, the trajectory correction unit sets one or more intermediate points between the transfer start position and the transfer stop position when a deviation of the trajectory occurs midway during correction of the trajectory having the transfer start position as a start point and the transfer stop position as an end point, The system is characterized by dividing the trajectory into a first trajectory that starts at the transport start position and ends at the midpoint, and a second trajectory that starts at the midpoint and ends at the transport stop position, and correcting the trajectory.

[0023] Even with this configuration, even if the distance between the transfer start position and the transfer stop position is very small, sufficient distance can be ensured between the transfer start position and the midpoint during the transfer, and between the midpoint and the transfer stop position, so the correction coefficient does not need to be excessively large and correction does not deviate from the trajectory around the midpoint. This makes it possible to appropriately correct the entire trajectory in accordance with the positional deviation of the transfer start position without impairing the trajectory characteristics obtained offline.

[0024] In a conveying device that conveys the object to be conveyed using a multi-joint robot type conveying mechanism in which a plurality of links are connected in a bendable manner, the conveying trajectory is represented by the angle of each link constituting the articulated robot, When correcting at least one of the angles of the links that indicate the conveying track, the trajectory correction unit When there is an inflection point where the direction of the angle change of the link is reversed before and after passing through, it is preferable to set the inflection point as the midpoint.

[0025] In this way, it is possible to effectively prevent the corrected trajectory from deviating from the offline trajectory, particularly at the inflection points.

[0026] It is desirable that the trajectory correction unit performs trajectory correction using the midpoint when a positional deviation at the transfer end point position with respect to the distance between the transfer start position and the transfer stop position is equal to or greater than a predetermined threshold value.

[0027] In this way, the possibility of deviation from the trajectory can be automatically predicted and the present invention can be applied.

[0028] In a preferred embodiment, the trajectory correction unit calculates a positional deviation amount of an intermediate position that serves as an end point when correcting the first trajectory, and an offset amount for offsetting the entire second trajectory in advance when correcting the second trajectory based on the first trajectory correction, The ratio of the transport time from the transport start position to the transport stop position to the transport time from the transport start position to the intermediate point is multiplied by the positional deviation amount at the transport stop position, and the result is used as the positional deviation amount of the intermediate target point during the first trajectory correction, and is also used as the offset amount.

[0029] In this way, the amount of positional deviation at the midpoint can be appropriately given, and the end point of the first corrected trajectory and the start point of the second corrected trajectory can be appropriately connected.

[0030] The present invention is particularly effective when installed in a transfer chamber whose interior is maintained in a vacuum. In such a transfer chamber, the transfer device operates at the very edge of the boundary conditions, so overshooting is not permitted. However, the present invention can appropriately prevent excessive trajectory correction. [Effects of the Invention]

[0031] As described above, the present invention makes it possible to provide a transport device that, when a positional deviation occurs between the initial transport position and the transport position obtained by teaching in a wafer transport robot, corrects the transport trajectory in accordance with the positional deviation without impairing the trajectory characteristics generated offline. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a configuration diagram schematically illustrating a basic configuration of a conveying device according to an embodiment of the present invention; [Figure 2] FIG. [Figure 3] FIG. 3 is an explanatory diagram of a conveying track preset in the conveying device. [Figure 4] FIG. 10 is an explanatory diagram regarding correction of a conveyance trajectory. [Figure 5] 10 is a flowchart executed by the transport control means to realize the trajectory correction unit. [Figure 6] FIG. 10 is an explanatory diagram illustrating a case where deviation of the trajectory occurs after correction. [Figure 7] FIG. 10 is an explanatory diagram illustrating division processing of trajectory correction with an intermediate point added according to the present invention. [Figure 8] This is a configuration diagram corresponding to Figure 1, with the addition of a division processing function for trajectory correction. [Figure 9] 10 is a flowchart showing a division processing procedure for trajectory correction. [Figure 10] Diagram showing the trajectory of the T-axis before and after adding an intermediate point. [Figure 11] 10A and 10B are diagrams showing the trajectory of the arm tip before and after adding an intermediate point. [Figure 12] FIG. 1 is a diagram illustrating Patent Document 1. [Figure 13] FIG. 1 is a diagram illustrating Patent Document 2. [Figure 14] FIG. 1 is a diagram illustrating Patent Document 2. [Figure 15] FIG. 10 is a diagram illustrating a defect in Patent Document 2. [Figure 16] FIG. 10 is a diagram illustrating a defect in Patent Document 2. [Figure 17] FIG. 10 is a diagram illustrating a defect in Patent Document 2. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0034] As mentioned above, the present invention aims to improve the drawbacks of Patent Document 2. First, the configuration and correction method of the conveying device 1 of Patent Document 2 will be explained, and then a correction method using trajectory division according to one embodiment of the present invention will be explained.

[0035] First, as shown in FIG. 1, the underlying transport device 1 has a transport mechanism 2 such as a robot arm that transports an object W to be transported, such as a wafer, and a transport control means 3 that drives the transport mechanism 2 to control the transport of the object W to be transported.

[0036] As shown in FIG. 2, the transport mechanism 2 is a so-called articulated robot arm in which multiple links 21, 22, and 23 are connected in series so as to be bendable. With the transport object W placed on a holder 23b set at the tip of the robot arm, the angle θ between each link is adjusted by driving a motor (not shown) at each joint. A θ B θ C The conveyance mechanism 2 of this embodiment is configured to convey the object W to a desired position by changing the position of the first link 21. The conveyance mechanism 2 of this embodiment includes a first link 21 having a base end 21a connected to a base 20, a second link 22 having a base end 22a connected to a tip 21b of the first link 21, and a third link 23 having a base end 23a connected to the tip 22b of the second link 22 and having a holder 23b at its tip for placing the object W to be conveyed, and the links 21 to 23 are connected so as to be rotatable in the horizontal direction to form a three-axis horizontal articulated robot. The lengths of the links 21 to 23 are set to L1, L2, and L3, respectively.

[0037] As shown in FIG. 1, the transfer control means 3 includes a transfer control unit 34, a trajectory correction unit 33, and trajectory data 31 pre-stored in memory. These units 33 and 34 are implemented through software and hardware cooperation, with the CPU of an information processing device, such as a microcomputer equipped with a CPU, ROM, and various interfaces, executing a pre-stored transfer control processing routine (not shown) and a trajectory correction processing routine (shown in FIG. 5). The transfer control means 3 is also communicatively connected to a position deviation detection device SE. The position deviation detection device SE detects a position deviation when the end point of the transfer target W in the transfer mechanism 2 is taught at a position deviated from the offline trajectory, and inputs a signal indicating the direction and distance of the deviation to the transfer control means. While the transfer device 1 and the position deviation detection device SE are separate devices in this embodiment, the transfer device may also be provided with a position deviation detection unit that performs the same function as the position deviation detection device SE.

[0038] As shown in FIG. 3, the offline trajectory data 31 is obtained by dividing a conveyance trajectory Pt, through which the center of the conveyed object W passes, into (N-1) equal parts at time intervals T, and dividing the trajectory data 31 into a plurality of points P including a start point S and an end point E. 1~N It is discrete data expressed as k XY coordinates of (X k ,Y k ) is calculated by the following equation to calculate the angle θ of each of the links 21 to 23 that constitute the transport mechanism 2: Ak θ Bk θ Ck It is expressed as: X k =L1cosθ Ak +L2cos(θ Ak +θ Bk )+L3cos(θ Ak +θ Bk +θ Ck ) Y k =L1sinθ Ak +L2sin(θ Ak +θ Bk )+L3sin(θ Ak +θ Bk +θ Ck )

[0039] The conveyance control unit 34 in FIG. 1 controls the driving of the conveyance mechanism 2 so that the conveyance object W is conveyed along the conveyance track Pt, as shown in FIG. 3. Specifically, the conveyance control unit 34 controls the driving of the conveyance mechanism 2 so that the conveyance object W is conveyed along the conveyance track Pt ... A θ B θ C The point P that constitutes the conveying track Pt 1~N Each link is rotated so that the angle of the link is as shown in the figure, and this rotation is continued from the start point S to the end point E to point P. k By executing this command sequentially, conveyance control along the conveyance track Pt is performed.

[0040] The trajectory correction unit 33 in Figure 1 receives a signal regarding positional deviation from the positional deviation detection device SE (process S1 in Figure 5), and determines the target end point E' shown in Figure 4(a) based on this signal (process S2 in Figure 5).If the target end point E' is deviated from the end point E of the predetermined conveying trajectory Pt, the trajectory correction unit 33 corrects the conveying trajectory Pt used by the conveying control unit 34 to the conveying trajectory Pt' so that the end point E of the conveying trajectory Pt becomes the target end point E' as shown in Figure 4(b) (processes S3 to S7 in Figure 5).

[0041] Specifically, as shown in FIG. 4, a case where the target end point E' is shifted only in the X direction from the end point E will be described as an example. In this embodiment, the angle θ of each link representing the conveyance track Pt Ak θ Bk θ Ck To make it easier to understand, we will explain it using XY coordinates, and then we will explain it using the angle θ Ak θ Bk θ Ck will be explained.

[0042] First, as shown in FIG. 4(a), the direction connecting the end point E and the target end point E' is defined as the deviation direction G (the direction along the X axis in this example), and the distance from the start point S to the end point E in the deviation direction is defined as the pre-correction distance d1 N The distance from the start point S to the target end point E' in the deviation direction component is set as the corrected distance d2 N The uncorrected distance d1 N Corrected distance d2 NThe ratio (d2 N / d1 N ) is calculated (process S4 in FIG. 5).

[0043] Next, each point P that composes the orbit Pt 1~N As shown in Figure 4(a), the following process is performed for each point. k Distance before correction d1 k (Step S5 in FIG. 5), and this distance d1 k to the above ratio (d2 N / d1 N ) to get the corrected distance d2 k (Step S6 in FIG. 5), and then, as shown in FIG. 4(b), k The distance in the direction of deviation of the distance to the k Point P k is moved along the deviation direction G (step S7 in FIG. 5). 1~N As shown in Figure 4(b), the corrected trajectory Pt' is composed of points P' 1~N At any point, the uncorrected distance d1 k and corrected distance d2 k The ratio of the trajectory Pt to the trajectory Pt′ remains the same, and the trajectory Pt is corrected to the trajectory Pt′.

[0044] The above correction process is performed for the angles θ of each link 21 to 23. A θ B θ C To explain, the X and Y coordinates of the target end point E' are calculated using the following formula: A θ' B θ' C Convert to. JPEG2025141062000002.jpg54165φ is the angle of the third link 23 shown in FIG. 2 with respect to the X axis at the target end point E' with respect to the start point S (the posture of the third link 23).

[0045] Next, the angle θ' obtained above A θ' B θ' C The above pre-correction distance d1 N (θ N-θ1), the corrected distance d2 N (θ' N -θ1) and calculate the above ratio (d2 N / d1 N ) corresponding to the ratio β=(θ' N -θ1) / (θ N The deviation direction G in the XY coordinate system is expressed as the direction of increase or decrease in angle θ.

[0046] Then, the calculated ratio β is used to calculate the distance between each point P that constitutes the trajectory Pt. 1~N For each link, the angle θ before correction A θ B θ C The corrected angle θ' A θ' B θ' C The process of converting into is performed sequentially. θ' k =β(θ k -θ1)+θ1

[0047] The above process is performed at point P 1~N As a result, the point P' that constitutes the corrected orbit Pt' is 1~N At any point, the uncorrected distance d1 k (θ k -θ1) and corrected distance d2 k (θ' k -θ1) remains the same, the trajectory Pt is corrected to the trajectory Pt'.

[0048] Here, when the speed ratio between the trajectory Pt before correction and the trajectory Pt' after correction is considered, The velocity before correction is approximately (θ k -θ k-1 ) / T The corrected velocity is approximately (θ' k -θ' k-1 ) / T=β(θ k -θ k-1 ) / T

[0049] T is expressed as the time interval between time point k and time point k-1, and it can be seen that the velocity before and after correction changes by only β times at each time point, and the acceleration also changes by β times. k If the difference is small compared to (β), β will be close to 1 and (β-1) will also be small, so the pre-correction trajectory Pt will be corrected to the post-correction trajectory Pt' while maintaining its characteristics. Moreover, smooth transport from the start point S to the post-correction target end point E' will be possible without temporarily stopping the transport operation at the pre-correction end point E.

[0050] However, in reality, as shown in Fig. 6, there are cases where the pre-correction distance d1n(L) between the transfer start position TS and the transfer stop position TE is minute, and the axis turns in one direction, then reverses and returns to a position close to the transfer start angle. If a trajectory correction is performed with the transfer start position TS as the start point S and the transfer stop position TE as the end point E, and the teaching position as the new end point E', there is a possibility that the distance D during movement will become excessively large, like D', as shown in Fig. 16(b), and the original offline trajectory Pt and transfer characteristics will be significantly impaired.

[0051] Therefore, in this embodiment, as a preliminary process before performing the trajectory correction SR in Figure 5, when the distance d1N(N) between the transport start position TS and the transport stop position TE is small, rather than performing the above correction with the transport start position TS as the start point S and the transport stop position TE as the end point E, one intermediate point M is set between the transport start position TS and the transport stop position TE, and the trajectory is corrected by dividing it into a first trajectory Pt1 with the transport start position TS as the start point S and the intermediate point M as the end point E, and a second trajectory Pt2 with the intermediate point M as the start point S and the transport stop position TE as the end point E, as shown in Figure 7.

[0052] For this purpose, the transport control means shown in FIG. 8, which is an improvement over the transport device in FIG. 1, is provided with a midpoint extraction unit 132a.

[0053] For example, in the example shown in FIG. 16(b), even if the distance L (d1N) between the start point and the end point is minute, the articulated robot temporarily deviates from the trajectory at some point, as indicated by the arrow D → D'. For example, the T axis, which is the shoulder joint shown in FIGS. 15 and 16, temporarily increases counterclockwise from the initial angle θ1 to a certain point, then reverses clockwise from that point and finally returns to a position θN close to the initial angle. Because the transfer start position and transfer stop position are close to each other, as shown in FIG. 16(b), the deviation of the trajectory from the offline trajectory Pt is greatest at the inflection point where the rotation direction reverses. Therefore, the system of this embodiment detects whether there is an inflection point in the direction of change in the rotation angle of any axis, and if an inflection point is detected, this inflection point is set as the midpoint M.

[0054] The trajectory correction unit 33 shown in Fig. 8 divides the trajectory data 31 of the offline trajectory Pt shown in Fig. 6 into trajectory data 131 consisting of trajectory data 131a of a first trajectory Pt1 from the transfer start position TS to the midpoint M as shown in Fig. 7(a) and Fig. 8, and trajectory data 131b of a second trajectory Pt2 from the midpoint M to the transfer stop position TE as shown in Fig. 7(b) and Fig. 8. Then, for the first trajectory Pt1, the first trajectory data 131a is corrected to eliminate positional deviation at the midpoint M, and for the second trajectory Pt2, the second trajectory data 131b is corrected to eliminate positional deviation from the target position E' remaining at the transfer stop position TE.

[0055] At the intermediate point M, there is a sufficient distance D1 between the intermediate point M and the transfer start position TS, so the denominator when calculating the correction coefficient does not become small.

[0056] In this case, the system does not have the amount (positional deviation data) to be corrected at the intermediate point M. Therefore, as one example, in the offline trajectory shown in Fig. 6, if there is an inflection point at position K of the total stroke distance F, and the amount of positional deviation at the transfer stop position E is L', the time required for transfer over the total stroke distance F is T, and the time required for transfer from the transfer start position S to position K is T', and if the amount of positional deviation L' is distributed over the transfer time T of the total stroke F, the positional deviation to be eliminated at position K is L' x T' / T, which becomes the intermediate target point E'.

[0057] Therefore, if the correction coefficient for the trajectory up to the midpoint M is β1, the correction coefficient β1 is β1=(D1+L´×K / F) / D1 and the denominator is not infinitesimal. Therefore, if the distance dk at each point from the transfer start position TS to the intermediate point M is corrected by enlarging or reducing it by the same ratio as above, the intermediate target point E' is corrected to a new intermediate point M2 near the intermediate point M, as shown by the dashed line in Figure 7(a). Therefore, the corrected trajectory Pt1' is made appropriate without deviating from the offline trajectory Pt1.

[0058] The same applies to the latter half of the trajectory correction Pt2 from the midpoint M to the transport stop position TE. However, it is necessary to take into consideration that the midpoint M has been corrected to a new midpoint M2, which must be set as the next start point S, and that the positional deviation L' at the target stop position E has been partially eliminated at the new midpoint M2.

[0059] Therefore, as one example of a corresponding response, as shown in Figure 7(b), the entire second trajectory Pt2 from the midpoint M of the offline trajectory to the stop position E is offset by the amount of correction made in the first half (correction amount α = L' × T' / T) to create trajectory Pt20, and the remaining positional deviation amount L' (1 - T' / T) is distributed proportionally over the transport time from F to K in the second half, while correcting the distance dk by the same ratio at each point from the midpoint M2 to the end point E2 after the offset.This will generate a trajectory Pt2' in which the end point E' is corrected to the target transport stop position TE', as shown by the dashed line in Figure 7(b).

[0060] The correction coefficient β2 here can be expressed using the distance D2 between the new midpoint M2 and the transfer start position TE as follows: β2=(D2-L´(1-T´ / T)) / D2 Since there is a sufficient distance D2 between the transfer start position and the target, the denominator is not infinitesimal. Therefore, if the same trajectory correction as above is performed, deviation from the trajectory will not occur, as shown by the dashed line in Figure 7(b).

[0061] The above explanation was given using Cartesian coordinates, but in reality the Cartesian coordinate system is converted into the rotation angle of each axis, Correction coefficient β=(θ' N -θ1) / (θ N -θ1) is β1=(θ' M -θ1) / (θ M -θ1) β2=(θ' N -θ M ) / (θ N -θ´ M ) The denominator of each correction coefficient does not become a minimum, which prevents the correction trajectory from deviating and overshooting.

[0062] Note that such two-stage correction is not always performed, but is performed when there is a high risk that the orbit correction will deviate from the offline orbit.

[0063] Specifically, in the case where the transport start position TS and the transport stop position TE are close to each other, this depends on the relative relationship with the amount of positional deviation, and therefore in this embodiment, a division process necessity determination unit 132b shown in Fig. 8 is provided. This division process necessity determination unit 132b performs division control by setting a midpoint M when the ratio γ of the amount of positional deviation L' to the distance L between the transport start position TS and the transport stop position TE shown in Fig. 6, i.e., L' / L, exceeds a threshold value (for example, 1).

[0064] 9 is a flowchart showing the procedure when the transfer control means executes the above. First, the division process necessity determination unit 132b determines whether the ratio γ is equal to or greater than a threshold value (step S11). If the result is NO, as shown in FIG. 6, the transfer start position TS is set as the start point S and the transfer stop position TE is set as the end point E (step S12), and the trajectory correction process SR is executed, and the process ends.

[0065] If the answer is YES in step S11, the midpoint extraction unit 132a detects whether there is an inflection point between the transfer start position TS and the transfer stop position TE (step S13). As described above, this is because the trajectory tends to deviate significantly from the offline trajectory at the inflection point.

[0066] If NO, as described above in step S12, the trajectory correction process SR is executed with the transfer start position TS as the start point S and the transfer stop position TE as the end point E, and then the process ends.

[0067] On the other hand, if the answer is YES in step S13, the inflection point is set to midpoint M (step S14). Then, a first trajectory correction SR1 (step S15) is executed to correct midpoint M to a new midpoint M2, with transfer start position TS as the start point S and midpoint M as the end point E, and a second trajectory correction SR2 (step S16) is executed to correct transfer stop position E to a target stop position E', with the new midpoint M2 as the start point S and transfer stop position TE as the end point E. Then, the corrected trajectories 1 and 2 are combined to form a new corrected trajectory (step S17), and the process ends.

[0068] Figure 10(b) shows the result of adding and setting a correction point, midpoint M, on the offline trajectory shown in Figure 10(a) and recalculating. As shown in Figure 10(b), the corrected trajectory has been corrected to a trajectory that passes almost through midpoint M (PM), and there is no deviation from the offline trajectory. The tip trajectory shown in Figure 11 also follows the original offline trajectory, and the deviation in the stopping position has been corrected without any deviation, as shown by the dashed line.

[0069] Moreover, the problem can be solved without complexity by simply adding the positions used when calculating the correction coefficients, without changing the correction formula.

[0070] And because the correction points can be determined in advance for the trajectory determined offline, there is no disruption to current operations. Furthermore, during operation, the offline trajectory is corrected online and output to the driver, so there is no decrease in transport efficiency. In other words, after moving the offline trajectory, there is no need to move to the teaching stop position.

[0071] As described above, the conveying device 1 according to this embodiment is a conveying device that conveys an object to be conveyed along a conveying trajectory Pt from a conveying start position TS to a conveying stop position TE, and is equipped with a trajectory correction unit 33 that corrects the conveying trajectory Pt so that the end point E of the conveying trajectory Pt becomes the target end point E' when conveyance control is performed using a conveying trajectory Pt that is set in advance from a certain start point S to a certain end point E, if the target end point E' is deviated from the end point E of the conveying trajectory Pt. The trajectory correction unit 33 defines the direction connecting the end point E before correction and the target end point E' after correction as the deviation direction G, and corrects the direction connecting the start point S on the trajectory Pt to a certain point P k The distance in the direction of deviation of the distance to k Then, a point P on the corrected trajectory Pt' is k The point located on the axis along the deviation direction passing through k After correction, the starting point S on the trajectory Pt' is k The distance in the direction of the deviation of the distance to the k Then, at a point P k The uncorrected distance d1 is the same as the distance d1 at any of the specified points on the orbit Pt. k and corrected distance d2 k The ratio of the starting point S to the uncorrected distance d1 k The trajectory Pt before correction is corrected to the trajectory Pt' after correction by enlarging or reducing the trajectory Pt along the deviation direction G.

[0072] If deviation of the trajectory occurs midway during correction of the trajectory from the transport start position TS as the starting point S to the transport stop position TE as the end point E, the trajectory correction unit 33 sets an additional intermediate point M between the transport start position TS and the transport stop position TE, and divides the trajectory into a first trajectory Pt1 with the transport start position TS as the starting point S and the intermediate point M as the end point E, and a second trajectory Pt2 with the intermediate point M as the starting point S and the transport stop position TE as the end point E, and corrects the trajectory.

[0073] As a result, even if the distance between the transfer start position TS and the transfer stop position TE is very small, a sufficient distance can be secured between the transfer start position TS and the midpoint M during the transfer, so the correction coefficient does not become excessively large. Therefore, it is possible to appropriately correct the entire transfer trajectory Pt (Pt1, Pt2) in accordance with the positional deviation of the transfer stop position TE without impairing the trajectory characteristics obtained offline.

[0074] In addition, in this embodiment, when the transport object W is transported using the transport mechanism 2 of the articulated robot type in which the plurality of links 21 to 23 are connected so as to be bendable, the transport trajectory Pt is determined by the angle θ Ak θ Bk θ Ck The trajectory correction unit 33 calculates the angle θ of each link that indicates the conveyance trajectory Pt. Ak θ Bk θ Ck When correcting the offset trajectory, if there is an inflection point where the direction of the link angle change reverses before and after passing through, the inflection point is set as the midpoint M, which effectively prevents the correction trajectory from deviating from the offset trajectory, especially at the inflection point.

[0075] Furthermore, when the positional deviation L' at the transport end position TE relative to the distance L between the transport start position TS and the transport stop position TE is equal to or greater than a predetermined threshold, the trajectory correction unit 33 performs division correction of the trajectory by adding and setting an intermediate point M, so that the possibility of deviation from the trajectory can be automatically predicted and the present invention can be applied.

[0076] Furthermore, when the trajectory correction unit 33 calculates the positional deviation amount of the intermediate position M, which is the end point E when correcting the first trajectory Pt1, and the offset amount for offsetting the entire second trajectory Pt2 in advance when correcting the second trajectory Pt2 based on the first trajectory correction, the trajectory correction unit 33 multiplies the ratio of the distance F between the transport start position TS and the transport stop position TE and the distance K between the transport start position TS and the intermediate point M by the positional deviation amount L' at the transport stop position TE to obtain the positional deviation amount of the intermediate target point E' when correcting the first trajectory Pt2, and also uses this as the offset amount.Therefore, the amount of positional deviation at the intermediate point M can be appropriately determined, and the end point of the first corrected trajectory Pt1' and the start point of the second corrected trajectory Pt2' can be appropriately connected.

[0077] This transport device 1 is installed and used in a transport chamber whose interior is kept under vacuum. In such a transport chamber, the transport device operates at the very edge of the boundary conditions, and therefore overshooting is not permitted. In light of this, the present invention makes it possible to appropriately prevent excessive trajectory correction and optimize transport.

[0078] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments.

[0079] For example, in this embodiment, the trajectory is corrected so that the end point E of the preset conveyance trajectory Pt becomes the target end point E', but as shown in FIG. 14, the trajectory may be corrected so that the start point S of the conveyance trajectory Pt becomes the target start point S'. In this case, similarly to the above, the ratio (d21 / d11) of the corrected distance d21 to the pre-correction distance d11 is calculated. Then, the point P k The uncorrected distance d1 of the deviation direction component of the distance from k Calculate this distance d1 k Multiply by the above ratio (d21 / d11) to get the corrected distance d2 k Calculate the point P k The distance from the end point E to the offset direction component is the corrected distance d2 k Point P kis moved along the deviation direction G. In this way, the position deviation of the starting point S can be corrected.

[0080] In such a case, if the distance between the start point S and the end point E of the conveying track Pt is small, the same effect as in the above embodiment can be achieved by adding an intermediate point and correcting the track by dividing it.

[0081] Additionally, although the above-described trajectory correction is applied to a transport device that uses a robot arm-type transport mechanism 2 in which multiple links are rotatably connected in series, it can also be applied to transport devices that use other transport mechanisms 2. For example, it can be a transport device such as a parallel manipulator in which multiple links are connected in parallel. Furthermore, although each functional unit shown in FIG. 1 is realized by executing a predetermined program on a processor, each functional unit may also be configured with a dedicated circuit.

[0082] Furthermore, when an intermediate point is extracted, it is possible to perform trajectory correction only from the intermediate point to the transfer stop position without performing correction from the transfer start position to the intermediate point. In this case, the first half of the trajectory will match the offline trajectory, and the trajectory will be corrected in the second half. In this way, it is not necessary to calculate the positional deviation at the midpoint or to offset the offline trajectory beyond the midpoint, so that the same effects as those of the above embodiment can be obtained simply.

[0083] Of course, the opposite may be made, and the trajectory correction may be performed only from the transfer start position to the midpoint, without correcting from the midpoint to the transfer stop position.

[0084] Furthermore, two or more intermediate points may be set. In this case, it is preferable to correct the trajectory by dividing it into at least one trajectory starting from the transfer start position and ending at the nearest intermediate point, and another trajectory ending at the transfer stop position and starting at the nearest intermediate point.

[0085] Furthermore, the specific configuration of each part is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0086] 21·22·23…Link 33...Trajectory correction section TS: Transfer start position TE: Transfer stop position S...Starting point S': Target starting point E...End point E' ... target end point M…Midway point Pt...Transport trajectory before correction Pt1: First transfer trajectory before correction Pt2: Second transport trajectory before correction Pt' ... Corrected transport trajectory Pt1´: First transfer trajectory after correction Pt2´: Second conveyance trajectory after correction W: Object to be conveyed G…Shift direction P k …a certain point P' k …Corresponding points d1 k …Distance before correction d2 k ...corrected distance θ Ak θ Bk θ Ck …link angle

Claims

1. A conveying device that conveys an object along a conveying track from a conveying start position to a conveying stop position, When carrying out conveyance control using a predetermined conveyance track from a certain start point to a certain end point, if a target end point is deviated from the end point of the conveyance track, a trajectory correction unit is provided which corrects the conveyance track so that the end point of the conveyance track becomes the target end point, the trajectory correction unit corrects the trajectory by expanding or contracting the pre-correction distance along the deviation direction using the starting point as a reference, so that the ratio between the pre-correction distance and the post-correction target distance is the same regardless of which of the predetermined points on the trajectory the certain point is located at, where the deviation direction is the direction connecting the pre-correction end point and the post-correction target end point, the pre-correction distance is the deviation direction component of the distance from the start point to a certain point on the pre-correction trajectory, and the corresponding point is a point on the post-correction trajectory that is located on an axis along the deviation direction and that passes through the certain point, the post-correction distance is the deviation direction component of the distance from the start point to the corresponding point, the trajectory correction unit sets one or more intermediate points between the transfer start position and the transfer stop position, A conveying device characterized in that the trajectory is divided into a trajectory having a conveyance start position as a start point and an intermediate point as an end point, and a trajectory having a intermediate point as a start point and a conveyance stop position as an end point, and the trajectory is corrected.

2. A conveying device that conveys an object along a conveying track from a conveying start position to a conveying stop position, When carrying out conveyance control using a predetermined conveyance track from a certain start point to a certain end point, if a target start point is deviated from the start point of the conveyance track, a trajectory correction unit is provided which corrects the conveyance track so that the start point of the conveyance track becomes the target start point, the trajectory correction unit corrects the trajectory by expanding or contracting the pre-correction distance along the deviation direction using the end point as a reference so that the ratio between the pre-correction distance and the post-correction distance is the same regardless of which of the predetermined points on the trajectory the certain point is located at, where the deviation direction is the direction connecting the pre-correction start point and the post-correction target start point, the pre-correction distance is the deviation direction component of the distance from a certain point on the pre-correction trajectory to the end point, and the corresponding point is a point on the post-correction trajectory that is located on an axis along the deviation direction and that passes through the certain point, the post-correction distance is the deviation direction component of the distance from the corresponding point on the post-correction trajectory to the end point, the trajectory correction unit sets one or more intermediate points between the transfer start position and the transfer stop position, A conveying device characterized in that the trajectory is corrected by dividing it into a first trajectory having a starting point at the conveying start position and an end point at an intermediate point, and a second trajectory having a starting point at the intermediate point and an end point at the conveying stop position.

3. A conveying device that conveys the object to be conveyed using a multi-joint robot type conveying mechanism in which a plurality of links are connected in a bendable manner, the conveying trajectory is represented by the angle of each link constituting the articulated robot, When correcting at least one of the angles of the links that indicate the conveying track, the trajectory correction unit 3. The conveying device according to claim 1, wherein when there is an inflection point where the direction of the angle change of the link is reversed before and after passing, the inflection point is set as the midpoint.

4. The conveying device according to claim 1 or 2, wherein the trajectory correction unit performs trajectory correction using the midpoint when a positional deviation at the conveying end position relative to the distance between the conveying start position and the conveying stop position is equal to or greater than a predetermined threshold.

5. the trajectory correction unit calculates a positional deviation amount of an intermediate position that serves as an end point when correcting the first trajectory, and an offset amount for offsetting the entire second trajectory in advance when correcting the second trajectory based on the first trajectory correction, 3. The conveying device according to claim 1, wherein the ratio of the conveying time from the conveying start position to the conveying stop position to the conveying time from the conveying start position to the intermediate point is multiplied by the positional deviation amount at the conveying stop position to obtain the positional deviation amount of the intermediate target point during the first trajectory correction, and also obtain the offset amount.

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