Line tracing method

Abstract

In this line tracing method, when a tool T is moved along a target trajectory P provided on a main surface of a workpiece W, a trajectory detection device S that moves together with the tool T is used, the trajectory detection device S defines detection areas A1, A2 through which the target trajectory P passes in at least two locations around the tool T, and a target position Pt of the tool T is determined on the basis of the positions P1, P2 of the target trajectory P detected in the detection areas A1, A2, whereby the trace accuracy can be improved even if the target trajectory P is obstructed by the tool T.

Description

Line tracing method

[0001] The present invention relates to a line tracing method used to move a tool such as a machining tool or a nozzle for applying adhesive along a target trajectory set on the main surface of a workpiece.

[0002] A conventional line tracing method is described, for example, in Patent Document 1. Patent Document 1 describes a microcontroller car that runs along a line drawn on the floor. This microcontroller car has left and right wheels that are driven independently and a detection unit in which multiple line sensors are arranged in the vehicle width direction, and while running, the left and right wheels are controlled according to the position of the line sensor that detects the line, thereby allowing the car to automatically run along the line.

[0003] Japanese Utility Model Registration No. 3097635

[0004] The above-described line tracing can be applied, for example, to an incremental forming process for metal plates in which a processing tool is moved relative to a workpiece, an adhesive application process in which a nozzle is moved relative to a workpiece, etc. However, when a tool such as a processing tool or an application nozzle is moved along a target trajectory while detecting a target trajectory set on the workpiece, there is a problem in that the target trajectory may be partially blocked by the tool, which may reduce tracing accuracy.

[0005] The present invention has been made in consideration of the above-mentioned conventional situation, and aims to provide a line tracing method that can improve tracing accuracy when detecting a target trajectory set on the main surface of a workpiece and moving a tool along the target trajectory, even if the target trajectory is obstructed by the tool.

[0006] The line tracing method according to the present invention uses a trajectory detection device that moves together with the tool when moving the tool along a target trajectory set on the main surface of the workpiece. The line tracing method is characterized in that the trajectory detection device sets detection areas, through which the target trajectory passes, in at least two locations around the tool, and determines the target position of the tool based on the position of the target trajectory detected in the detection areas.

[0007] By adopting the above-described configuration, the line tracing method of the present invention detects a target trajectory set on the main surface of the workpiece and moves a tool along the target trajectory, so that even if the target trajectory is obstructed by the tool, the position error of the tool can be corrected to improve tracing accuracy.

[0008] FIG. 10 is an explanatory diagram of the main parts showing a first embodiment of the line tracing method. FIG. 11 is a perspective view showing a tool and a trajectory detection device. FIG. 12 is an explanatory diagram of the main parts showing a second embodiment of the line tracing method. FIG. 13 is an explanatory diagram of the main parts showing a third embodiment of the line tracing method. FIG. 14 is an explanatory diagram of the main parts showing a fourth embodiment of the line tracing method. FIG. 15 is an explanatory diagram of the main parts showing a fifth embodiment of the line tracing method. FIG. 16 is an explanatory diagram of the main parts showing a sixth embodiment of the line tracing method. FIG. 17 is an explanatory diagram of the main parts showing the sixth embodiment together with FIG. 7. FIG. 18 is an explanatory diagram of the main parts showing a seventh embodiment of the line tracing method.

[0009] 1 and 2 are diagrams showing a first embodiment of a line tracing method according to the present invention. That is, the line tracing method uses a trajectory detection device S that moves together with the tool T when moving the tool T along a target trajectory P provided on the main surface of a plate-shaped workpiece W.

[0010] The target trajectory P can be drawn directly on the workpiece W, formed by scanning with laser light, or projected. In the illustrated example, the target trajectory P is drawn directly on the workpiece W, and may be colored appropriately to make it easier to detect on the workpiece W.

[0011] The tool T is, for example, a processing tool or a nozzle for applying adhesive, and is attached to the hand H of the work robot shown in Fig. 2 and held so as to be movable in at least one axial direction (X or Y direction) parallel to the main surface of the workpiece W. The tool T may be movable in two axial directions (X and Y directions), or may be movable in an axial direction (Z direction) perpendicular to the main surface of the workpiece W and rotatable around the Z axis.

[0012] As shown in Figure 2, the trajectory detection device S is attached to the hand H of the work robot and is movable together with the tool T. A camera or scanner can be used for this trajectory detection device S. The trajectory detection device S in the illustrated example is a camera that captures an image of a certain range including the tip of the tool T. Figure 1 shows an image of the trajectory detection device S.

[0013] In the line tracing method, a trajectory detection device S sets a front detection area A1 and a rear detection area A2 through which the target trajectory P passes at at least two locations around the tool T, more preferably two locations before and after the moving direction (the direction of the arrow in FIG. 1) of the tool T. In this case, in a more preferred embodiment, the front and rear detection areas A1 and A2 form a line or a band that the target trajectory P intersects.

[0014] The front and rear detection areas A1, A2 in the illustrated example are rectangular, i.e., strip-shaped, with the longer sides extending in the vertical direction in Fig. 1. Because the trajectory detection device S is a camera, these detection areas A1, A2 are made up of pixel groups determined by the number of pixels in the X and Y directions in the image shown in Fig. 1, and the position of the target trajectory P can be detected by image processing.

[0015] The line tracing method determines a target position of the tool T based on the position of the target trajectory P detected in the detection areas A1 and A2. More specifically, the line tracing method determines a target position Pt at the midpoint of a line connecting a position P1 of the target trajectory P in the front detection area A1 and a position P2 of the target trajectory P in the rear detection area A2, as shown in Fig. 1 , and moves the tool T so that the target position Pt and the center Tc of the tool T coincide with each other.

[0016] In other words, the above-mentioned line tracing method sets detection areas A1 and A2 at at least two locations around the tool T, more preferably two locations before and after the movement direction of the tool T, and identifies the positions P1 and P2 of the target trajectory P, thereby determining an approximation line of the target trajectory P and the target position Pt, and moving the tool T.

[0017] As a result, when the line tracing method detects a target trajectory P set on the main surface of the workpiece W and moves the tool T along the target trajectory P, even if the target trajectory P is blocked by the tool T, as shown by the dotted line in Figure 1, the position error of the tool T can be corrected to improve tracing accuracy.

[0018] Furthermore, in the above-described line tracing method, by setting detection areas A1 and A2 that are linear or strip-shaped and intersect with the target trajectory P, if the trajectory detection device S is a camera, the range in which image processing is performed can be reduced, thereby increasing the calculation speed and realizing rapid control.

[0019] Furthermore, the above-mentioned line tracing method enables a more accurate calculation of the target position Pt by setting forward and backward detection areas A1 and A2 before and after the direction of movement of the tool T, and in particular, the target position Pt can be determined with high accuracy even in areas on the target trajectory P where the curvature is relatively large, which can contribute to further improving the tracing accuracy.

[0020] In the above line tracing method, the orientations of the tool T and the trajectory detection device S may be kept constant and the tool T may be moved along the target trajectory P, or the orientations of the tool T and the trajectory detection device S may be controlled to be constant relative to the target trajectory. However, if the orientations of the tool T and the trajectory detection device S gradually change, some measures may be taken to prevent the cables from becoming tangled, or wireless data communication may be employed.

[0021] 2 to 9 are diagrams illustrating second to seventh embodiments of the line tracing method according to the present invention. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0022] Second Embodiment In the line tracing method shown in FIG. 3, a detection area A is set by a trajectory detection device S, the detection area A being in the shape of a ring and arranged coaxially with the center line of a tool T.

[0023] In the line tracing method of this embodiment, positions P1 and P2 of the target trajectory P are detected at two locations, one before the other and one after the other in the direction of movement of the tool T, in one detection area A. As a result, in the above line tracing method, as in the first embodiment, even if the target trajectory P is blocked by the tool T, the position error of the tool T can be corrected to improve tracing accuracy.

[0024] 4, a trajectory detection device S sets two detection areas that form annular shapes and are arranged coaxially with respect to the center line of a tool T. The two detection areas are an inner detection area A3 and an outer detection area A4 that have different diameters.

[0025] In the line tracing method of this embodiment, in each of the detection areas A3 and A4, positions P1 to P4 of the target trajectory P are detected at four locations before and after the direction of movement of the tool T. As a result, in the above line tracing method, as in the first embodiment, even if the target trajectory P is blocked by the tool T, the position error of the tool T can be corrected to improve tracing accuracy.

[0026] Furthermore, in the above-described line tracing method, by increasing the number of detected positions P1 to P4 of the target trajectory P, the approximation line of the target trajectory P connecting these positions becomes more accurate, thereby enabling further improvement in tracing accuracy.

[0027] 5, a trajectory detection device S sets a plurality of band-shaped front detection areas A1 on the front side in the movement direction of the tool T. In the illustrated example, five front detection areas A1 are set. Note that the line tracing method according to the present invention is only required to detect at least two positions on the target trajectory P, and is therefore not limited to two positions in front and behind the movement direction of the tool T, and two positions in front or two positions in back may also be detected.

[0028] The above line tracing method can achieve the same effects as the first embodiment, and can also calculate an approximation line (shown by the thick dotted line) based on the position P1 of the target trajectory P in the multiple detection areas A1, even if the target trajectory P disappears due to processing or adhesive application, as shown by the thin dotted line in the figure, thereby improving the detection accuracy of the target position Pt. This can improve the processing accuracy and adhesive application accuracy.

[0029] 6, a track detection device S sets a plurality of strip-shaped detection areas A1 and A2 on the front and rear sides, respectively, of the moving direction of a tool T. In the illustrated example, five detection areas A1 and A2 are set on the front and rear sides, respectively.

[0030] The above-mentioned line tracing method can obtain the same effect as the first embodiment, and can detect multiple positions P1, P2 of the target trajectory P in the detection areas A1, A2 respectively before and after the movement direction of the tool T, allowing the target position Pt to be set and the tool T to be moved with high precision. In particular, when the target trajectory P is a curve, by calculating an approximation curve using a higher-order curve, even higher precision can be achieved in setting the target position Pt and moving the tool T.

[0031] 7, the trajectory detection device S is rotatable around the center line of the tool T. In this case, the device configuration can be such that the trajectory detection device (camera) S can be rotated by rotating the hand H of the working robot around the Z axis, as described above, or a structure can be employed in which the trajectory detection device (camera) S is rotatably attached to the hand H.

[0032] In the above line tracing method, the trajectory detection device S is rotated in a direction that reduces the angle θ of the line connecting the position P1 of the target trajectory P detected in the front detection area A1 and the position P2 of the target trajectory P detected in the rear detection area A2. This angle θ is, for example, the angle with respect to the movement direction of the tool T. In other words, in the above line tracing method, since the detection areas A1 and A2 are set in two locations, one before and one after the movement direction of the tool T, the fact that the line connecting the two positions P1 and P2 on the image is inclined means that the target trajectory P is inclined with respect to the movement direction of the tool T.

[0033] If the line connecting the two positions P1 and P2 on the image is inclined as described above, if the tool T and the trajectory detection device S continue to move in the same direction, the target trajectory P may deviate from the front detection area A1, as shown on the right side of Figure 7.

[0034] Therefore, in the above line tracing method, when the line connecting the two positions P1 and P2 is inclined, as shown in Figure 8, the trajectory detection device S is rotated in a direction that reduces the angle θ of the line connecting the two positions P1 and P2 so that the target trajectory P passes through both the front and rear detection areas A1 and A2, and the target position Pt is determined and the tool T is moved, as in the previous embodiment. In this way, the above line tracing method, as in the previous embodiment, can correct the position error of the tool T and improve tracing accuracy even if the target trajectory P is blocked by the tool T.

[0035] 9 uses two trajectory detection devices (cameras) S1 and S2 that move together with a tool T. One of the trajectory detection devices S1 sets detection areas A1 and A2 in front and behind the target trajectory P, in at least two locations around the tool T in the X-axis direction of the workpiece W, more preferably in two locations before and after the moving direction of the tool T, as shown in the top-bottom view on the left side of FIG.

[0036] 9, the other trajectory detection device S2 sets detection areas A1 and A2 on the front and rear sides through which the target trajectory P passes, in at least two locations around the tool T in the Y-axis direction of the workpiece W, more preferably two locations before and after the moving direction of the tool T. In other words, the two trajectory detection devices S1 and S2 are arranged so as to capture images of the tool T from directions that are 90 degrees different from each other.

[0037] In the line tracing method, the trajectory detection devices S1, S2 determine the target position Pt of the tool T based on the positions P1, P2 of the target trajectory P detected in the respective detection areas A1, A2. In this case, as shown in the lower right diagram in Fig. 9, the line tracing method determines the actual movement amount Lt by combining the movement amount L1 of the tool T determined based on the data from one trajectory detection device S1 and the movement amount L2 of the tool T determined based on the data from the other trajectory detection device S2, and moves the tool T accordingly.

[0038] As with the previous embodiment, the above line tracing method can correct the position error of the tool T to improve tracing accuracy even if the target trajectory P is blocked by the tool T, and can perform processing and adhesive application on the target trajectory P consisting of a closed curve without tangling cables.

[0039] The detailed configuration of the line tracing method according to the present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention, and the configurations of the above-described embodiments can also be combined. Furthermore, the line tracing method according to the present invention is a method that can be implemented in macro (robot arm) and micro (handheld high-speed vision-based compensation system) systems such as experimental systems, and can also be applied to systems that only have a robot arm.

[0040] A Detection area A1 Front detection area A2 Rear detection area P Target trajectory P1, P2 Position of target trajectory Pt Target position S Trajectory detection device S1 One trajectory detection device S2 Other trajectory detection device T Tool W Work

Claims

1. A line tracing method comprising the steps of: when moving a tool along a target trajectory set on the main surface of a workpiece, using a trajectory detection device that moves together with the tool, setting detection areas through which the target trajectory passes in at least two locations around the tool using the trajectory detection device, and determining a target position of the tool based on the position of the target trajectory detected in the detection areas.

2. A line tracing method according to claim 1, characterized in that the detection area is a line or band that intersects with the target trajectory.

3. A line tracing method according to claim 1, characterized in that the detection area forms a ring shape arranged coaxially with respect to the center line of the tool.

4. A line tracing method as described in any one of claims 1 to 3, characterized in that the trajectory detection device sets the detection areas, which are a front detection area and a rear detection area, before and after the movement direction of the tool.

5. A line tracing method as described in claim 4, characterized in that the trajectory detection device is rotatable around the center line of the tool, and the trajectory detection device is rotated in a direction that reduces the angle of a line connecting the position of the target trajectory detected in the front detection area and the position of the target trajectory detected in the rear detection area.

6. The line tracing method according to claim 4, characterized in that the trajectory detection device sets a plurality of the front detection areas on the forward side in the moving direction of the tool.

7. A line tracing method as described in claim 6, characterized in that the trajectory detection device is rotatable around the center line of the tool, and the trajectory detection device is rotated in a direction in which the angle of a line connecting the positions of the target trajectory detected in the multiple front detection areas becomes smaller.

8. The line tracing method according to claim 4, characterized in that the trajectory detection device sets a plurality of front detection areas and rear detection areas in front of and behind the moving direction of the tool, calculates an approximation curve based on the positions of the target trajectory detected in the plurality of front detection areas and rear detection areas, and determines the target position of the tool on the approximation curve.

9. The line tracing method according to claim 1, further comprising: two trajectory detection devices that move together with the tool; one of the trajectory detection devices sets detection areas through which the target trajectory passes in at least two locations around the tool in the X-axis direction of the workpiece; and the other trajectory detection device sets detection areas through which the target trajectory passes in at least two locations around the tool in the Y-axis direction of the workpiece; and the target position of the tool is determined based on the position of the target trajectory detected in each of the detection areas.

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