Line tracing method and line tracing system

Abstract

This line tracing method uses a sub-driving device (12) that drives a tool (17) in a direction parallel to a processing surface of a workpiece (W) and a main driving device (11) that drives the sub-driving device in three orthogonal-axis directions XYZ for driving the tool (17) along a target trajectory (TT) by the sub-driving device while driving the sub-driving device along a basic trajectory (BT) by the main driving device. When the position of the tool (17) driven by the sub-driving device (12) is included in a limit region of a movable range of the tool in one of the X-axis direction and the Y-axis direction, and the driving direction of the tool driven by the sub-driving device is directed to the limit of the limit region, a driving command value to the sub-driving device with respect to the one of the X-axis direction and the Y-axis direction is reduced.

Description

Line tracing method and line tracing system

[0001] The present invention relates to a line tracing method and a line tracing system, and more particularly to a line tracing method and a line tracing system that are suitable for use in moving a tool such as a machining tool or an adhesive application nozzle along a target trajectory set on the main surface of a workpiece.

[0002] A known conventional line tracing method is a method for creating an NC program for incremental forming, in which incrementally formed portions are extracted from the 3D CAD data of a product, processing conditions for the extracted incrementally formed portions are determined, the extracted incrementally formed portions are broken down into unit shapes, and the movement trajectory of an incrementally formed tool corresponding to each unit shape is calculated based on the processing conditions (Patent Document 1).

[0003] Japanese Patent Application Publication No. 11-327619

[0004] However, the above-mentioned conventional technology is a method of creating an NC program for incremental forming, and uses a numerically controlled processing machine such as an articulated robot to move a tool along the movement trajectory of the created NC program. The NC processing machine then decelerates and accelerates or temporarily stops, repeating this process, so that the tool accurately passes through the movement trajectory. Therefore, the above-mentioned conventional technology has a problem in that it cannot handle installation errors in the processing machine or the workpiece.

[0005] The problem to be solved by the present invention is to provide a line tracing method and a line tracing system that can cope with installation errors in the processing machine or the workpiece.

[0006] The present invention solves the above problem by reducing the drive command value to the sub-drive unit in either the X-axis direction or the Y-axis direction when the position of the tool driven by the sub-drive unit is within the limit region of the movable range of the tool in either the X-axis direction or the Y-axis direction, and the drive direction of the tool driven by the sub-drive unit is toward the limit of the limit region.

[0007] According to the present invention, it is possible to deal with installation errors in the processing machine or the workpiece.

[0008] 1B is a front view showing a line tracing system according to an embodiment of the present invention. FIG. 1A is a right side view of FIG. 1A. FIG. 1B is a bottom view of FIG. FIG. 1B is a perspective view showing an example of a trajectory setting device according to an embodiment of the present invention. FIG. 1C is a view showing a method for detecting a target trajectory by a first trajectory detection device and a second trajectory detection device according to an embodiment of the present invention, and a method for driving a tool using the detection results (a view of the machining surface of a workpiece when viewed from above). FIG. 1D is a plan view showing a target trajectory, a movable range of a driving sub-device, and a basic trajectory according to an embodiment of the present invention. FIG. 1F is a plan view showing driving of a tool on a basic trajectory according to an embodiment of the present invention. FIG. 1G is a plan view showing an auxiliary driving device and a tool for explaining a malfunction in a limit region of the movable range. FIG. 1H is a plan view showing the operation of the tool executed in the line tracing system and the line tracing method according to an embodiment of the present invention. FIG. 1H is a flowchart showing processing executed by a control device according to an embodiment of the present invention. FIG. 1I is a plan view showing the operation of the tool executed in the line tracing system and the line tracing method according to an embodiment of the present invention.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a front view showing one embodiment of a line tracing system, FIG. 1B is a right side view of FIG. 1A, FIG. 1C is a bottom view of FIG. 1A, and FIG. 1D is a bottom view of FIG. 1B. The drive direction of the tool 17 driven by the auxiliary drive unit 12 of the line tracing system 1 according to this embodiment is represented by the X-axis and the Y-axis, and the drive direction of the auxiliary drive unit 12 driven by the main drive unit 11 is represented in a three-dimensional space by adding the Z-axis to the X-axis and Y-axis. Furthermore, in this specification, "drive" refers to moving by applying power, and "movement" refers to moving or shifting. For example, it is expressed as "the auxiliary drive unit 12 drives the tool 17 in accordance with a drive command value from the control unit 16, thereby moving the tool 17 in the X-axis direction." In some cases, these terms may have the same meaning.

[0010] The line tracing system 1 of this embodiment can be applied, for example, to an incremental forming process in which a processing tool is moved relative to a metal plate that is a workpiece to plastically process the metal plate, or to an application process in which a nozzle is moved relative to the workpiece to apply an adhesive or sealant to the workpiece. Below, an embodiment in which the line tracing system according to the present invention is applied to a process in which a metal plate that is a workpiece is incrementally formed into a predetermined product shape will be given, and the line tracing system and line tracing method according to the present invention will be described.

[0011] The line tracing system 1 according to this embodiment includes a main driving device 11 , a secondary driving device 12 , a trajectory setting device 13 , a first trajectory detection device 14 , a second trajectory detection device 15 , and a control device 16 .

[0012] The main drive unit 11 of this embodiment is a drive unit that drives the auxiliary drive unit 12 in three orthogonal axis directions, and can be used with a numerically controlled processing machine such as an articulated industrial robot or an NC machine tool. For example, if an industrial robot is used as the main drive unit 11, the auxiliary drive unit 12 is attached to the hand unit 111 of the industrial robot. This allows the auxiliary drive unit 12 to be driven in three orthogonal axis directions (X-axis, Y-axis, and Z-axis). The main drive unit 11 may also be configured to rotate the auxiliary drive unit 12 about the three orthogonal axes.

[0013] The driving sub-unit 12 of this embodiment is a driving sub-unit that drives the tool 17 in a direction parallel to the workpiece W. As shown in the front view of FIG. 1A , the right side view of FIG. 1B , and the bottom views of FIG. 1C and FIG. 1D , the driving sub-unit 12 of this embodiment includes a rectangular frame 121, a beam 122 held by the frame 121 and movable reciprocally in the X-axis direction relative to the frame 121, and a slider 123 held by the beam 122 and movable reciprocally in the Y-axis direction relative to the beam 122, and the tool 17 is fixed to the slider 123. In other words, the frame 121, the beam 122, and the slider 123 form an XY stage between the driving sub-unit 11 and the tool 17.

[0014] Between the frame 121 and beam 122 constituting the X-axis direction drive mechanism of the XY stage, there are provided a linear guide (not shown) which allows the beam 122 to reciprocate in the X-axis direction relative to the frame 121, and an X-axis actuator 124 which moves the beam 122 back and forth a predetermined distance in the X-axis direction relative to the frame 121. Furthermore, between the beam 122 and slider 123 constituting the Y-axis direction drive mechanism of the XY stage, there are provided a linear guide (not shown) which allows the slider 123 to reciprocate in the Y-axis direction relative to the beam 122, and a Y-axis actuator 125 which moves the slider 123 back and forth a predetermined distance in the Y-axis direction relative to the beam 122. As a result, the tool 17 fixed to the slider 123 can be driven in two axial directions (X-axis direction and Y-axis direction) horizontal to the machining surface of the workpiece W relative to the main drive unit 11 to which the frame 121 is fixed.

[0015] 1A, a workpiece W made of a metal plate such as a steel plate or an aluminum plate is set horizontally below the driving sub-unit 12 with its periphery restrained by clamps 2. A rod-shaped tool 17 having a tip of an appropriate shape is held by the driving sub-unit 12 with its tip pointing downward.

[0016] The trajectory setting device 13 of this embodiment is a device that detectably sets a target trajectory TT for the tool 17 on the machining surface of the workpiece W, and examples thereof include a device that directly draws the target trajectory TT on the workpiece W, a device that displays the target trajectory TT by scanning with laser light, and a device that projects the target trajectory TT onto the workpiece W. FIG. 2 is a perspective view showing an example of the trajectory setting device 13 of this embodiment. The illustrated trajectory setting device 13 is a projection device that projects a target trajectory TT corresponding to the shape of the formed portion onto the machining surface of the workpiece W by scanning with laser light. Note that the trajectory setting device 13 of this embodiment is not an essential component of the line tracing system 1, and may be omitted as appropriate if the target trajectory TT is set in a previous process, for example.

[0017] 1A to 1D, the first trajectory detection device 14 of this embodiment is fixed to a slider 123 to which the tool 17 is fixed so as to move together with the tool 17, with its line of sight directed in the Y-axis direction, and detects a target trajectory TT of the workpiece W in the X-axis direction, and outputs this detection result to the control device 16. The control device 16 controls the X-axis actuator 124 based on the detection result of the first trajectory detection device 14, and drives the tool 17 in the X-axis direction. The first trajectory detection device 14 of this embodiment can be constituted by a CCD camera or the like, and captures an image of a certain range including the tip of the tool 17 and the machined surface of the workpiece W.

[0018] 1A and 1B , the second trajectory detection device 15 of this embodiment is fixed to a slider 123 to which the tool 17 is fixed so as to move together with the tool 17, with its line of sight directed in the X-axis direction, and detects a target trajectory TT of the workpiece W in the Y-axis direction, and outputs this detection result to the control device 16. The control device 16 controls the Y-axis actuator 125 based on the detection result of the second trajectory detection device 15, and drives the tool 17 in the Y-axis direction. The second trajectory detection device 15 of this embodiment can be constituted by a CCD camera or the like, and captures an image of a certain range including the tip of the tool 17 and the machined surface of the workpiece W.

[0019] 3 is a diagram showing a method for detecting a target trajectory TT by the first trajectory detection device 14 and the second trajectory detection device 15 of this embodiment, and a method for driving the tool 17 using the detection results, and is a plan view of the machining surface of the workpiece W. In the line tracing system 1 of this embodiment, the two first trajectory detection devices 14 and the second trajectory detection device 15 are arranged so as to capture images of the tool 17 and the target trajectory TT from directions orthogonal to each other.

[0020] In the figure, assuming that the horizontal axis is the X axis and the vertical axis is the Y axis, one first trajectory detection device 14 detects the target trajectory TT within a detection region R1 including the tool 17, as shown in the upper left diagram of Fig. 3. Then, as shown in the lower left diagram of Fig. 3, a front detection area A1 and a rear detection area A2 through which the target trajectory TT passes are set in at least two locations around the tool 17 in the X-axis direction of the workpiece W, more preferably in two locations before and after the movement direction of the tool 17.

[0021] In contrast, the other second trajectory detection device 15 detects the target trajectory TT within a detection region R2 that includes the tool 17, as shown in the upper left diagram of Fig. 3. Then, as shown in the upper right diagram of Fig. 3, a front detection area A1 and a rear detection area A2 through which the target trajectory TT passes are set in at least two locations around the tool 17 in the Y-axis direction of the workpiece W, more preferably in two locations before and after the movement direction of the tool 17.

[0022] The line tracing system 1 of this embodiment determines a target position Pt of the tool 17 based on positions P1 and P2 of the target trajectory TT detected in the respective detection areas A1 and A2 by the first trajectory detection device 14 and the second trajectory detection device 15. In this case, the target position Pt may be, for example, the midpoint of a line connecting the two positions P1 and P2.

[0023] 3, a drive command value corresponding to a movement amount L1 of the tool 17 in the X-axis direction, determined based on data from the first trajectory detection device 14, is output to the X-axis actuator 124, thereby driving the beam 122 in the X-axis direction. At the same time, a drive command value corresponding to a movement amount L2 of the tool 17 in the Y-axis direction, determined based on data from the second trajectory detection device 15, is output to the Y-axis actuator 125, thereby driving the slider 123 in the Y-axis direction. In this way, the beam 122 and the slider 123 are simultaneously driven in the X-axis direction and the Y-axis direction, respectively, and their resultant vector becomes the actual movement amount Lt of the tool 17, causing the tool 17 to move along the target trajectory TT. In particular, the movement of the tool 17 is decomposed into movement in the X-axis direction and movement in the Y-axis direction, and the XY stage, the X-axis actuator 124, and the Y-axis actuator 125 are used to control the respective actuators, thereby significantly simplifying the control process and improving control responsiveness.

[0024] 1A, the control device 16 of this embodiment is composed of a computer including a ROM storing software, a RAM as a temporary storage device, and a CPU, and controls the main drive device 11 and the auxiliary drive device 12 based on the detection results of the first track detection device 14 and the second track detection device 15. The control device 16 of this embodiment can be mounted on the main drive device 11 and used in common, or it can be configured to control the main drive device 11 and the auxiliary drive device 12 separately.

[0025] In order to execute the following line tracing method, the control device 16 of this embodiment has the functions of setting a target trajectory TT corresponding to the shape of the forming portion in the workpiece W, setting the movable range of the tool 17 by the sub-drive unit 12 based on the target trajectory TT, setting a basic trajectory BT of the sub-drive unit 12 by the main drive unit 11 within the movable range, and driving the tool 17 along the target trajectory TT by the sub-drive unit 12 while driving the sub-drive unit 12 along the basic trajectory BT by the main drive unit 11.

[0026] 4 is a plan view showing the target trajectory TT, the movable range of the drive sub-unit 12, and the basic trajectory BT. In the line tracing method of this embodiment, as shown in FIG. 4, a target trajectory TT is set that corresponds to the shape of the forming portion of the workpiece W. The formed part shown in the figure is an engine hood outer panel of an automobile, with the upper side indicating the front side of the vehicle body. The target trajectory TT shown in the figure is a trajectory that follows the contour of the engine hood outer panel, which is the formed part.

[0027] Next, in the line tracing method of this embodiment, the total movable range E of the tool T by the drive sub-unit 12 (gray hatched range) is set based on the target trajectory TT. In this case, the movable range of the tool 17 in the drive sub-unit 12 is the range in the X-axis direction and Y-axis direction parallel to the workpiece W, as shown in four places in Figure 4, so the total movable range E based on the target trajectory TT is the entire area when the center of the drive sub-unit 12 is moved along the target trajectory TT, and has a certain width on both sides of the target trajectory TT.

[0028] Next, in the line tracing method of this embodiment, a basic trajectory BT of the sub-drive device 12 is set by the main drive device 11 within the entire movable range E. The basic trajectory BT can have an arbitrarily simple shape compared to the target trajectory TT, which may have a complex shape. The basic trajectory BT in the illustrated example is rectangular with curvature (curves) at the corners. Note that the shape of the basic trajectory BT is not limited to the illustrated example, and a simple shape such as a circle or ellipse is more preferable.

[0029] When setting the basic trajectory BT, the main drive unit 11 sets set points (coordinates) PP to be passed on the basic trajectory BT in order to move the center of the secondary drive unit 12 along the basic trajectory BT. However, as described above, the basic trajectory BT in this embodiment has a simple shape, so the number of set points PP can be significantly reduced. In the example shown in the figure, two set points PP are set at each of the four corners of the basic trajectory BT, for a total of eight set points PP, and these set points PP are input to the control device 16 of the main drive unit 11.

[0030] In the line tracing method of this embodiment, the tool 17 is pressed against the workpiece W, and the main drive unit 11 moves the sub-drive unit 12 along a basic trajectory BT, which has a simple shape. The sub-drive unit 12 then drives the tool 17 in the direction indicated by the arrow in accordance with the difference and direction between the basic trajectory BT and the target trajectory TT, as shown in FIG. 5 . FIG. 5 is a plan view showing the movement of the tool 17 on the basic trajectory BT, with the arrows indicating the driving distance and driving direction of the tool 17. In this case, the line tracing system 1 of this embodiment moves the sub-drive unit 12 while holding it in a fixed orientation using the main drive unit 11, and the XY stage of the sub-drive unit 12 drives the tool 17 in the X-axis and Y-axis directions.

[0031] As a result, the tool 17 moves along the target trajectory TT while making contact with the workpiece W, and then moves in a circular motion along the contour lines, gradually pressing down the bottom to form a concave plastically. Note that the target trajectory TT and the basic trajectory BT become smaller each time the tool 17 makes a revolution, but the control for moving the tool 17 based on the difference between the two remains the same.

[0032] In the incremental forming method using the line tracing method according to this embodiment, the number of set points PP on the basic trajectory BT is significantly reduced, so the movement speed of the auxiliary drive unit 12 by the main drive unit 11 can be increased accordingly. Furthermore, the auxiliary drive unit 12 has a smaller mass and higher responsiveness than the main drive unit 11, so it can drive the tool 17 at high speed so that it follows the target trajectory TT while moving at high speed. This makes it possible to shorten the forming time even if the forming portion of the workpiece W has a complex shape.

[0033] Furthermore, the incremental molding method using the line tracing method according to this embodiment employs a rectangular shape with curvature at the corners as the shape of the basic trajectory BT, which makes it easy to control the main drive unit 11 and allows continuous molding without having to stop the secondary drive unit 12 at the corners, thereby contributing to further shortening the molding time.

[0034] In the line tracing system and line tracing method of the present embodiment described above, the control content is significantly simplified and control responsiveness is improved by independently controlling the movement amount L1 in the X-axis direction and the movement amount L2 in the Y-axis direction, as explained in Figure 3. However, because the movement amount L1 in the X-axis direction and the movement amount L2 in the Y-axis direction are independently controlled, operational problems occur near the movement limits in each axial direction.

[0035] FIG. 6 is a plan view showing the drive sub-unit 12 and the tool 17 to explain this problem. In the figure, the dotted rectangular line indicates the entire movable range E of the tool 17 by the drive sub-unit 12, the reference symbol 12C indicates its movable origin, and the reference symbol 12C indicates the current position of the tool 17. If the X-axis direction movement amount L1 and the Y-axis direction movement amount L2 relative to the target trajectory TT are calculated independently at the current time shown in the figure, the Y-axis direction movement amount L2 may reach the limit of the Y-axis movable range, as shown in the figure. In this case, the tool 17 is driven by the X-axis direction movement amount L1. However, although a drive command value corresponding to the Y-axis movement amount L2 is output to the Y-axis actuator 125 in the Y-axis direction, the XY stage of the drive sub-unit 12 (specifically, the slider 123 relative to the beam 122) reaches its physical and mechanical movement limit, and therefore cannot be driven by the movement amount L2. As a result, the actual tool 17' deviates from the target trajectory TT, as shown in the figure. Reference symbol 17' indicates the position of the tool when the movement limit is reached.

[0036] Therefore, in the line tracing system 1 and line tracing method of this embodiment, when the position of the tool 17 driven by the sub-drive unit 12 is included in the limit area of ​​the movable range of the tool 17 in either the X-axis direction or the Y-axis direction, and the driving direction of the tool 17 driven by the sub-drive unit 12 is toward the limit of the limit area, control is executed to reduce the drive command value to the sub-drive unit 12 in either the X-axis direction or the Y-axis direction.

[0037] Here, the case where the position of the tool 17 is included in the limit region of the movable range of the tool 17 in either the X-axis direction or the Y-axis direction is not particularly limited and various margins can be set, but for example, if the current position coordinate of the tool 17 in the X-axis direction or the Y-axis direction is P, the movable range coordinate of the tool 17 in the X-axis direction or the Y-axis direction is R, and the margin constant is a (a is a constant from 0 to 1), it can be determined that the position of the tool 17 is included in the limit region when the position of the tool 17 satisfies |P|≧|a·R|. In this case, if the margin constant a is 0.9, the limit region of the movable range is a range of 10% from the movable limit.

[0038] 7 , the plan view showing the drive sub-unit 12 and the tool 17 indicates that the entire movable range E of the tool 17 is expressed as an XY coordinate system with the movable origin 12C as the origin (the first quadrant has positive X and Y values, the second quadrant has negative X and positive Y values, the third quadrant has negative X and Y values, and the fourth quadrant has positive X and negative Y values), and the current position coordinate of the tool 17 in the X-axis or Y-axis direction is P and the drive command value to the drive sub-unit 12 is ΔD. When the drive direction of the tool 17 satisfies P·ΔD≧0, it can be determined that the drive direction of the tool 17 is toward the limit of the limit region.

[0039] Here, the position coordinate P of the tool 17 and the drive command value ΔD are positive or negative (or 0) values ​​defined in the XY coordinate system with the movable origin 12C as the origin. For example, if the current position coordinate P of the tool 17 is in the second quadrant of the XY coordinate system (the X coordinate has a negative value) and the tool 17 is further driven in the negative direction of the X axis from here, ΔD will become a negative value, and therefore P·ΔD≧0 will be satisfied. Therefore, in this case, the drive direction of the tool 17 will be toward the limit of the limit region.

[0040] In this embodiment, the decrease control (which is also suppression control) of the drive command value is executed when the position of the tool 17 is included in a limit area in either the X-axis direction or the Y-axis direction and the drive direction of the tool 17 is toward the limit of the limit area. Even if the position of the tool 17 is included in the limit area, the decrease control (which is also suppression control) is not executed when the drive direction of the tool 17 is not toward the limit of the limit area. Furthermore, even if the drive direction of the tool 17 is toward the limit of the limit area, the decrease control is not executed when the position of the tool 17 is not included in the limit area. This is because in either of these cases, the tool 17 will not reach its movement limit or the possibility of this happening is extremely low.

[0041] The reduction value of the reduction control of the drive command value in this embodiment is not particularly limited as long as it is less than the absolute value of the initially calculated drive command value, but for example, if the current position coordinate of the tool in the X-axis or Y-axis direction is P, a predetermined function β(P) (β(P) is a value between 0 and 1) that changes depending on the position coordinate P, and the drive command value to the sub-drive device 12 is ΔD, the drive command value can be reduced to a drive command value that satisfies ΔD' = β(P) · ΔD.

[0042] Here, the predetermined function β(P) is not particularly limited as long as it is a function that varies between 0 and 1. For example, if the current position coordinate of the tool 17 in the X-axis or Y-axis direction is P, the coordinate of the entire movable range of the tool 17 in the X-axis or Y-axis direction is R, and an arbitrary adjustment constant greater than 0 is γ, the predetermined function β(P) can be set as β(P) = γ |(R - P) / R|. Here, |(R - P) / R| on the right-hand side indicates the ratio of the limit region to the entire movable range R, and β(P) is a function that converges to 0 as P approaches the limit of the limit region. Therefore, the drive command value ΔD' becomes smaller (the amount of decrease in the drive command value becomes greater) as the current position coordinate P of the tool 17 approaches the limit of the limit region, thereby efficiently preventing the tool 17 from reaching its movable limit.

[0043] 7 is a plan view showing the operation of the tool executed in the line tracing system and line tracing method according to the embodiment of the present invention. In the state shown in FIG. 6, the movement amount L1 in the X-axis direction and the movement amount L2 in the Y-axis direction relative to the target trajectory TT are each calculated independently. However, as shown in the figure, the movement amount L2 in the Y-axis direction reaches the limit of the Y-axis movable range. In the Y-axis direction, although a drive command value corresponding to the movement amount L2 is output to the Y-axis actuator 125, the XY stage of the sub-drive unit 12 (specifically, the slider 123 relative to the beam 122) reaches its physical and mechanical limit, and therefore, it cannot be driven by the movement amount L2. Therefore, the actual tool 17' deviates from the target trajectory TT as shown in the figure.

[0044] In contrast to this, in this embodiment, the movement amount L2 in the Y-axis direction that was initially determined in accordance with the procedure described above is reduced to L2', and a drive command value ΔD' corresponding to this movement amount L2' is output to the Y-axis actuator 125. As a result, the tool 17" moves to a position that is a vector combination of the movement amount L1 in the X-axis direction and the movement amount L2' in the Y-axis direction, and as a result, the tool 17" overlaps with the target trajectory TT without reaching the movement limit.

[0045] 8 is a flowchart showing the process executed by the control device 16 according to the embodiment of the present invention. The process of this flowchart is executed by the control device 16 at predetermined time intervals.

[0046] First, in step S1, a movement amount ΔD of the tool 17 is calculated. As described with reference to Fig. 3, the movement amount ΔD is calculated by determining a movement amount ΔDx of the tool 17 in the X-axis direction based on data from the first track detection device 14, and determining a movement amount ΔDy of the tool 17 in the Y-axis direction based on data from the second track detection device 15.

[0047] In the next step S2, it is determined whether the current position of the tool 17 is included in the limit region of the movable range of the tool 17 in either the X-axis direction or the Y-axis direction. Specifically, when the current position coordinate of the tool 17 in the X-axis direction or the Y-axis direction is P, the movable range coordinate of the tool 17 in the X-axis direction or the Y-axis direction is R, and a margin constant is a (a is a constant between 0 and 1), it is determined whether the position of the tool 17 satisfies |P|≧|a·R|. If the condition is not satisfied in either the X-axis direction or the Y-axis direction, the process proceeds to step S4, and drive command values ​​corresponding to the movement amounts ΔDx and ΔDy calculated in step S1 are output to the X-axis actuator 124 and the Y-axis actuator 125, respectively.

[0048] On the other hand, if |P|≧|a·R| is satisfied in either the X-axis direction or the Y-axis direction, the process proceeds to step S3 for that axis direction, and proceeds to step S4 for the axis direction for which |P|≧|a·R| is not satisfied. In step S4, for the axis direction for which |P|≧|a·R| is not satisfied, a drive command value corresponding to the movement amount ΔDx, ΔDy calculated in step S1 is output to the X-axis actuator 124 or the Y-axis actuator 125.

[0049] In the following step S3, it is determined whether the drive direction of the tool 17 is a direction toward the limit of the limit area. Specifically, when the current position coordinate of the tool 17 in the X-axis or Y-axis direction is P and the drive command value to the drive sub-device 12 is ΔD, it is determined whether the drive direction of the tool 17 satisfies P·ΔD≧0. If the drive direction of the tool 17 does not satisfy P·ΔD≧0, the process proceeds to step S4 for that axial direction, and in step S4, a drive command value corresponding to the movement amount ΔDx, ΔDy calculated in step S1 is output to the X-axis actuator 124 or the Y-axis actuator 125.

[0050] On the other hand, if the drive direction of the tool 17 satisfies P·ΔD≧0, the process proceeds to step S5, where the drive command value for the satisfied axial direction is reduced. Specifically, when the current position coordinate of the tool in the X-axis or Y-axis direction is P, a predetermined function β(P) (β(P) is a value between 0 and 1) that changes depending on the position coordinate P, and the drive command value to the drive sub-device 12 is ΔD, the drive command value is reduced to ΔD' that satisfies ΔD'=β(P)·ΔD.

[0051] As a result, as shown in FIG. 7, even if the current position of the tool 17 in the Y-axis direction is included in the limit region of the movable range of the tool 17 (step S2) and the driving direction of the tool 17 is toward the limit of the limit region (step S3), the amount of movement in the Y-axis direction is reduced to L2', so that the tool 17" moves to a position obtained by vector-combining the amount of movement L1 in the X-axis direction and the amount of movement L2' in the Y-axis direction. As a result, the tool 17" overlaps with the target trajectory TT without reaching the movable limit.

[0052] Figure 9 is a plan view showing the operation of the tool executed by the line tracing system 1 and line tracing method according to an embodiment of the present invention, and is a diagram showing how the tool 17 operates after the drive command value of the tool 17 is reduced and controlled as shown in Figure 7. The left diagram in Figure 9 shows the tool 17 at time t0 shown in Figure 7 and the tool 17" at the next time t1. The middle diagram in Figure 9 shows the case where the movable origin 12C at time t1 moves downward in the XY coordinate system at the subsequent time t2, and the right diagram in Figure 9 shows the case where the movable origin 12C at time t1 moves upward in the XY coordinate system at the subsequent time t3.

[0053] 9, when the movable origin 12C at time t1 moves downward in the XY coordinate system at a subsequent time t2, the tool 17 moves toward the movable origin 12C of the entire movable range E, and thus moves away from the movable limit. Also, as shown in the right diagram of FIG. 9, when the movable origin 12C at time t1 moves upward in the XY coordinate system at a subsequent time t3, the tool 17 approaches further toward the movable limit, but in this case too, the reduction control of the drive command value operates, and the tool 17 is prevented from reaching the movable limit.

[0054] As described above, the line tracing system 1 and line tracing method of this embodiment use the sub-drive unit 12 that drives the tool 17 in a direction parallel to the machining surface of the workpiece W, and the main drive unit 11 that drives the sub-drive unit 12 in the three orthogonal axial directions X, Y, and Z, and provide a detectable target trajectory TT for the tool 17 on the machining surface of the workpiece W, set an entire movable range E of the tool 17 by the sub-drive unit 12 based on the target trajectory TT, set a basic trajectory BT of the sub-drive unit 12 by the main drive unit 11 within the entire movable range E, and drive the sub-drive unit 12 along the basic trajectory BT by the main drive unit 11 while driving the tool 17 along the target trajectory TT by the sub-drive unit 12. In the case of driving the tool 17 along the X-axis direction, a first trajectory detection device 14 that moves together with the tool 17 and detects the position of the target trajectory TT in the X-axis direction of the workpiece W, and a second trajectory detection device 15 that moves together with the tool 17 and detects the position of the target trajectory TT in the Y-axis direction of the workpiece W that is not parallel to the X-axis direction, are used, and the tool 17 is driven in the X-axis direction by the auxiliary driving device 12 based on the position of the target trajectory TT in the X-axis direction detected by the first trajectory detection device 14, and at the same time, the tool 17 is driven in the Y-axis direction by the auxiliary driving device 12 based on the position of the target trajectory TT in the Y-axis direction detected by the second trajectory detection device 15, When the position of the tool 17 driven by the drive sub-unit 12 is included in the limit region of the movable range of the tool 17 in either the X-axis direction or the Y-axis direction, and the drive direction of the tool 17 driven by the drive sub-unit 12 is toward the limit of the limit region, the drive command value to the drive sub-unit 12 in either the X-axis direction or the Y-axis direction is reduced, so that the tool 17" overlaps with the target trajectory TT without reaching the movable limit. As a result, it is possible to deal with installation errors in the processing machines, such as the main drive unit 11 and the drive sub-unit 12, or the workpiece W. It is also possible to deal with cases where the workpiece W is moving, and further, it is possible to shorten the teaching time and the program creation time. Furthermore, even if the target trajectory TT of the tool 17 has a complex shape, it is possible to shorten the movement time of the tool 17.

[0055] Furthermore, in the line tracing system 1 and line tracing method of this embodiment, the current position coordinate of the tool 17 in the X-axis or Y-axis direction is P, the movable range coordinate of the tool 17 in the X-axis or Y-axis direction is R, and a margin constant is a (a is a constant between 0 and 1). If the position of the tool 17 satisfies |P|≧|a·R|, the position of the tool 17 is determined to be within the limit area. Therefore, a desired safety factor can be set by setting the margin constant to a desired value. The tool 17″ will then overlap with the target trajectory TT without reaching its movable limit. As a result, it is possible to accommodate installation errors in the processing machine, such as the main drive unit 11 and the auxiliary drive unit 12, or the workpiece W. It is also possible to accommodate a moving workpiece W, further reducing teaching time and program creation time. Furthermore, it is possible to shorten the movement time of the tool 17 even if the target trajectory TT of the tool 17 has a complex shape.

[0056] Furthermore, in the line tracing system 1 and line tracing method of this embodiment, the current position coordinate of the tool 17 in the X-axis or Y-axis direction is P, and the drive command value to the drive sub-unit 12 is ΔD. If the drive direction of the tool 17 satisfies P·ΔD≧0, it is determined that the drive direction of the tool 17 is toward the limit of the limit region, so the direction of the tool 17 can be easily determined. The tool 17″ will then overlap with the target trajectory TT without reaching the movement limit. As a result, it is possible to accommodate installation errors in the processing machines, such as the main drive unit 11 and the drive sub-unit 12, or the workpiece W. It is also possible to accommodate even if the workpiece W is moving, and further, it is possible to shorten the teaching time and program creation time. Furthermore, it is possible to shorten the movement time of the tool 17 even if the target trajectory TT of the tool 17 has a complex shape.

[0057] Furthermore, in the line tracing system 1 and line tracing method of this embodiment, where P is the current position coordinate of the tool 17 in the X-axis or Y-axis direction, β(P) is a predetermined function that varies depending on the position coordinate P (β(P) is a value between 0 and 1), and ΔD is the drive command value to the drive sub-unit 12, the line tracing system 1 and the line tracing method reduce the drive command value to one that satisfies ΔD' = β(P) · ΔD, so it is possible to set a desired reduction value according to the predetermined function. The tool 17" then overlaps with the target trajectory TT without reaching its movement limit. As a result, it is possible to accommodate installation errors in the processing machines, such as the main drive unit 11 and the drive sub-unit 12, or the workpiece W. It is also possible to accommodate a moving workpiece W, further reducing teaching time and program creation time. Furthermore, it is possible to shorten the movement time of the tool 17 even if the target trajectory TT of the tool 17 has a complex shape.

[0058] Furthermore, in the line tracing system 1 and line tracing method of this embodiment, where P is the current position coordinate of the tool 17 in the X-axis or Y-axis direction, R is the movable range coordinate of the tool 17 in the X-axis or Y-axis direction, and γ is an arbitrary adjustment constant greater than 0, β(P) is set to β(P) = γ |(R - P) / R|. Therefore, the closer the current position coordinate P of the tool 17 is to the limit of the limit area, the smaller the drive command value ΔD' becomes (the greater the amount of decrease in the drive command value). This makes it possible to efficiently prevent the tool 17 from reaching its limit of movement. The tool 17" then overlaps with the target trajectory TT without reaching its limit of movement. As a result, it is possible to accommodate installation errors in the processing machine, such as the main drive unit 11 and the auxiliary drive unit 12, or the workpiece W. It is also possible to accommodate a moving workpiece W, further reducing teaching time and program creation time. Furthermore, it is possible to shorten the movement time of the tool 17 even if the target trajectory TT of the tool 17 has a complex shape.

[0059] In the above-described embodiment, the main drive unit 11 and the auxiliary drive unit 12 are configured as separate devices, but a single device (e.g., a robot) may have the functions of the main drive unit 11 and the auxiliary drive unit 12.

[0060] DESCRIPTION OF SYMBOLS 1...Line tracing system 11...Main drive unit 111...Hand unit 12...Sub-drive unit 12C...Movable origin 121...Frame 122...Beam 123...Slider 124...X-axis actuator 125...Y-axis actuator 13...Trajectory setting device 14...First trajectory detection device 15...Second trajectory detection device 16...Control device 17...Tool 2...Clamp W...Work TT...Target trajectory BT...Basic trajectory A1, A2...Detection area P1, P2...Position Pt...Target position PP...Set point R1, R2...Detection area E...Total movable range

Claims

1. Using a sub-drive unit that drives a tool in a direction parallel to the machining surface of a workpiece, and a main drive unit that drives the sub-drive unit in three orthogonal axial directions, a target trajectory of the tool is set so as to be detectable on the machining surface of the workpiece, an entire movable range of the tool by the sub-drive unit is set based on the target trajectory, a basic trajectory of the sub-drive unit by the main drive unit is set within the entire movable range, and while the main drive unit drives the sub-drive unit along the basic trajectory, the sub-drive unit drives the tool along the target trajectory, using a first trajectory detection device that moves with the tool and detects the position of the target trajectory in the X-axis direction of the workpiece, and a second trajectory detection device that moves with the tool and detects the position of the target trajectory in the Y-axis direction of the workpiece, which is not parallel to the X-axis direction, A line tracing method in which the tool is driven in the X-axis direction by the sub-drive unit based on the position of the target trajectory in the X-axis direction detected by the first trajectory detection device, and at the same time, the tool is driven in the Y-axis direction by the sub-drive unit based on the position of the target trajectory in the Y-axis direction detected by the second trajectory detection device, wherein, when the position of the tool driven by the sub-drive unit is included in a limit region of a movable range of the tool in either the X-axis direction or the Y-axis direction, and the drive direction of the tool driven by the sub-drive unit is toward a limit of the limit region, the line tracing method reduces a drive command value to the sub-drive unit in either the X-axis direction or the Y-axis direction.

2. A line tracing method as described in claim 1, wherein the current position coordinate of the tool in the X-axis direction or the Y-axis direction is P, the coordinate of the movable range of the tool in the X-axis direction or the Y-axis direction is R, and a margin constant is a (a is a constant from 0 to 1), and if the position of the tool satisfies |P|≧|a·R|, it is determined that the position of the tool is included in the limit area.

3. A line tracing method as described in claim 1 or 2, in which the current position coordinate of the tool in the X-axis or Y-axis direction is P, a drive command value to the sub-drive device is ΔD, and if the drive direction of the tool satisfies P·ΔD≧0, it is determined that the drive direction of the tool is toward the limit of the limit area.

4. A line tracing method as claimed in any one of claims 1 to 3, wherein, when the current position coordinate of the tool in the X-axis direction or the Y-axis direction is P, a predetermined function β(P) (β(P) is a value between 0 and 1) that changes depending on the position coordinate P, and a drive command value to the secondary drive device is ΔD, the drive command value is reduced to a value that satisfies ΔD' = β(P) · ΔD.

5. The line tracing method according to claim 4, wherein β(P) is set to β(P) = γ · |(R - P) / R|, where P is the current position coordinate of the tool in the X-axis or Y-axis direction, R is the coordinate of the movable range of the tool in the X-axis or Y-axis direction, and γ is an arbitrary adjustment constant greater than 0.

6. A system comprising: a sub-drive unit which drives a tool in a direction parallel to a workpiece; a main drive unit which drives the sub-drive unit in three orthogonal axial directions; a first trajectory detection unit which moves together with the tool and detects a target trajectory of the tool which is detectably provided on the machining surface of the workpiece in the X-axis direction of the workpiece; a second trajectory detection unit which moves together with the tool and detects the target trajectory in the Y-axis direction of the workpiece which is not parallel to the X-axis direction; and a control unit which controls the main drive unit and the sub-drive unit based on detection results of the first trajectory detection unit and the second trajectory detection unit, wherein the control unit: sets a total movable range of the tool by the sub-drive unit based on the target trajectory; sets a basic trajectory of the sub-drive unit by the main drive unit within the total movable range; drives the tool along the target trajectory by the sub-drive unit while driving the sub-drive unit along the basic trajectory by the main drive unit; A line tracing system in which, when the tool is driven in the X-axis direction by the sub-drive unit based on the position of the target trajectory in the X-axis direction detected by the first trajectory detection device, and at the same time, the tool is driven in the Y-axis direction by the sub-drive unit based on the position of the target trajectory in the Y-axis direction detected by the second trajectory detection device, if the position of the tool driven by the sub-drive unit is included in a limit region of a movable range of the tool in either the X-axis direction or the Y-axis direction and the drive direction of the tool driven by the sub-drive unit is toward the limit of the limit region, the system reduces a drive command value to the sub-drive unit in either the X-axis direction or the Y-axis direction.

7. The line tracing system according to claim 6, further comprising a trajectory setting device for detectably setting the target trajectory of the tool on the machining surface of the workpiece.

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