WO2008032591A1

WO2008032591A1 - Work transfer apparatus

Info

Publication number: WO2008032591A1
Application number: PCT/JP2007/067028
Authority: WO
Inventors: Takahiro Maeda; Michiharu Tanaka
Original assignee: Kabushiki Kaisha Yaskawa Denki
Priority date: 2006-09-12
Filing date: 2007-08-31
Publication date: 2008-03-20
Also published as: KR20090050024A; KR101310003B1; TW200832599A; TWI423377B; JPWO2008032591A1; JP5120258B2

Abstract

A position of a control point is kept by correcting warping caused by inertia moment operated while an arm of a robot is extending and retracting. In a control device (104) for controlling operation of the robot composed of a plurality of shafts, warping caused by inertia moment generated at the time of extending and retracting the arm by following an operation instruction given by an operation program previously stored in the storage means and an operation instruction given from an instructing means (106) arranged in the control device (104), is corrected by degree of freedom of the robot operated in the direction opposite to the warping direction.

Description

Specification

Work transfer device

Technical field

TECHNICAL FIELD [0001] The present invention relates to a work transfer device that transfers a work gripped by a work gripping device by horizontally moving an arm that is cantilevered with respect to a support portion, and in particular, a control point that is shifted due to the stagnation of the arm. The present invention relates to a work transfer device capable of correcting a position. Background art

In a semiconductor manufacturing system that processes a substrate such as a glass substrate for liquid crystal or a semiconductor wafer, a processing unit is arranged for each processing step, and the substrate is sequentially transported to these processing units. A series of treatments are performed on the substrate.

Figure 7 shows the configuration of the workpiece transfer device. Here, a state is shown in which a robot 102 composed of a plurality of axes inserts a glass substrate 107 into a substrate capacity setting set 100 for temporarily storing a plurality of substrates after a series of processing steps. The robot 102 operates by being supplied with motor driving power from the control device 104 via the cable 103. The control device 104 is connected to the teaching means 106 via a cable 105. The teaching means 106 has a plurality of buttons, and outputs an instruction to the control device 104 via the cable 105 by pressing each button. The control device 104 outputs motor driving power to the robot 102 via the cable 103 in accordance with the above instructions. The teaching means 106 may be a general-purpose computer or a personal computer, for example. The substrate capacity setting set 100 includes support pins 101 for holding or supporting the glass substrate 107.

FIG. 8 shows the configuration of the robot 102. The first arm link 108 is supported by the turning unit 129 via the first arm shaft 114. The first arm link 108 includes an arm shaft motor 115 and is connected to the arm shaft speed reducer 116. As the arm shaft motor 115 rotates, the first arm link 108 is supported by the turning force 129 and the force S to rotate the first arm shaft 114 connected to the arm shaft speed reducer 116. The first arm link 108 is provided with a first link belt 117 inside the first arm link 108 to reduce the arm axis speed. Power is transmitted from the machine 116 to the second arm shaft speed reducer 119 connected to the second arm shaft 118. The second arm shaft reducer 119 has a characteristic of rotating in the opposite direction to the arm shaft reducer 116. That is, when the arm shaft motor 115 rotates, the first link belt 117 is driven, the second arm shaft speed reducer 119 rotates, the connected second arm shaft 118 rotates, and the second arm link 109 rotates. It turns in the opposite direction to the first arm axis 114 around the two arm axis 118. A second link belt 120 is provided inside the second arm link 109, and power is transmitted from the second arm shaft speed reducer 119 to the flange speed reducer 121. The flange reducer 121 has a characteristic of rotating in the opposite direction to the second arm shaft reducer 119. Also, the reduction ratio of each reducer (arm shaft reducer 116, second arm shaft reducer 119, flange reducer 121) is set so that the rotation angle of the first arm shaft 114 and the rotation angle of the flange 122 are equal. It has been. Also, the distance from the turning center of the first arm shaft 114 to the turning center of the second arm shaft 118 and the distance from the turning center of the second arm shaft 118 to the turning center of the flange 122 are set to be equal. It is.

[0004] From the above mechanism, when the arm shaft motor 115 rotates, the first arm shaft 114 connected to the arm shaft speed reducer 116 rotates, and at the same time, the first link belt 117 is moved from the arm shaft speed reducer 116. The power is transmitted through the second arm shaft speed reducer 119. As the second arm shaft reducer 119 rotates, the connected second arm shaft 118 rotates in the opposite direction to the first arm shaft 114, and at the same time, the second arm shaft reducer 119 passes through the second link belt 120. The power is transmitted and the flange reducer 121 rotates. As the flange reducer 121 rotates, the connected flange 122 rotates in the opposite direction to the second arm shaft 118, that is, in the same direction as the first arm shaft 114. Further, the rotation angle of the first arm shaft 114 and the rotation angle of the flange 122 are equal to each other. The distance from the rotation center of the first arm shaft 114 to the rotation center of the second arm shaft 118 and the rotation center of the second arm shaft 118 are the same. Since the distance from the center of rotation to the rotation center of the flange 122 is equal, the workpiece gripping device 110, the glass substrate 10 7 gripped or placed by the workpiece gripping device 110, and the control device 104 are subject to motion control. The control point 123 that is a virtual point to be moved is linearly moved in the X-axis direction.

[0005] FIGS. 9 and 10 show a state where the arms (first arm link and second arm link) of the robot 102 are extended and contracted. 9 and 10 are views of the robot shown in FIG. 8 as viewed from the positive direction of the Z-axis. In the figure, a indicates the distance from the turning center of the first arm shaft 114 to the turning center of the second arm shaft 118. Since a is equal to the distance from the turning center of the second arm shaft 118 to the turning center of the flange 122, the turning center of the first arm shaft 114, the turning center of the second arm shaft 118, and the turning center of the flange 122 are A triangle formed by connecting line segments is an isosceles triangle shown in the figure. The bases rl and r2 of the isosceles triangle are distances from the pivot center of the first arm shaft 114 to the pivot center of the flange 122 (arm expansion / contraction length). For example, when the first arm shaft 114 rotates α 1 times, the angle formed by the line connecting the first arm shaft 114 to the second arm shaft 118 and the line connecting the first arm shaft 114 to the flange 122 is / 3 1 Since the flange 122 pivots from the mechanism described above in the opposite direction to the second arm shaft 118 by the same angle as the first arm shaft, the direction of the cake gripping device 110 is from the second arm shaft 118 to the flange 122. The direction is an angle / 3 1 counterclockwise from the extended line (see Fig. 9). For example, when the first arm shaft 114 is turned α 2, this angle is / 32 (see FIG. 10). Therefore, the direction of the workpiece gripping device 110 can be kept constant when the arm is extended and contracted. The expansion / contraction length r of the arm can be obtained by equation (1).

r = 2asin (a)… (1)

In FIG. 8, the lifting shaft motor 124 is connected to a reduction gear (not shown), and is driven to a reduction gear (not shown) connected to the lifting installation unit 125 by a belt (not shown) provided inside the lower lifting link 1 12. Has been communicated. Further, a speed reducer (not shown) connected to the lift shaft motor 124 and a speed reducer (not shown) connected to the lifting support 126 are not shown in the upper lifting link 111, and are driven by a belt. Being! / A speed reducer (not shown) connected to the lift installation part 125 and a speed reducer (not shown) connected to the lift support part 126 have a characteristic of rotating in the opposite direction to the speed reducer connected to the lift shaft motor 124. Further, the distance from the turning center of the lifting / lowering installation part 125 to the turning center of a reduction gear (not shown) connected to the lifting / lowering shaft motor 124 and the reduction gear (not shown) connected to the lifting / lowering support part 126 from the turning center of the lifting / lowering shaft motor 124. The distance to the turning center is equal. From the above configuration, when the lifting shaft motor 124 rotates, the not shown and the speed reducer connected to the lifting shaft motor 124 rotate. Inside of lift link 112 and top of lift link 111 A belt (not shown) provided in each of them is driven, and a speed reducer (not shown) connected to the lifting / lowering mounting part 125 and a speed reducer connected to the lifting / lowering support part 126 are connected to the lifting / lowering shaft motor 124. The workpiece gripping device 110, the gripped glass substrate 107, and the control point 123 move in the Z-axis linear direction in accordance with the operation of the lifting support unit 126.

[0007] The elevation of the robot 102 is shown in more detail in FIG. In the figure, b indicates the distance from the rotation center of the lifting shaft motor 124 to the rotation center of a reduction gear (not shown) connected to the lifting support 126. b is equal to the distance from the center of rotation of the lifting / lowering mounting part 125 to the center of rotation of the speed reducer (not shown) connected to the lifting / lowering shaft motor 124. The triangle formed by the line connecting the rotation centers of the lift installation part 125 is an isosceles triangle. The base z of the isosceles triangle is the distance from the center of rotation of the lift installation part 125 to the center of rotation of the lift support part 126. For example, when the lifting shaft motor 1 24 forces γ rotation, the angle formed by the lower lifting link 112 and the shaft zero reference 127 and the angle formed on the extension line of the upper lifting link 111 from the shaft is γ. Keep the orientation of the に対する axis. The elevation amount ζ is obtained by the equation (2).

z = 2bsin (y) (2)

FIG. 12 shows a state where the robot 102 shown in FIG. 8 is viewed from the positive direction of the Z axis. The pivot 130 is connected to a reduction gear (not shown). The reduction gear is connected to a turning shaft motor 128 shown in FIG. The turning shaft 130 is connected to the turning portion 129, and the turning portion 129 is connected to the main body arm support portion 113. When the turning shaft motor 128 rotates, the connected reduction gear (not shown) rotates, and the turning shaft 130 rotates. As the turning shaft 130 rotates, the connected turning unit 129 turns in the turning positive direction 131 or the turning negative direction 132.

A series of flow of substrate transfer using the robot 102 will be described with reference to FIGS. Figure 13 shows the robot that inserts the workpiece gripping device into the board capacity set as seen from the Z-axis direction. When inserting the workpiece gripping device 110 into the board holding power set 100, the first arm shaft 114 is rotated to move the arm to the board holding power set 100 in the positive X-axis direction. In general, since the support pins 101 are provided in advance at a sufficient interval to allow the comb-shaped tip of the workpiece gripping device 110 to pass, the cake gripping device 110 can be inserted between the support pins 101. Substrate housing with multiple support pins 134 similar to support pins 101 When inserting the workpiece gripping device 110 into the cassette 133, the workpiece gripping device 110 must be in a state where it can be inserted into the board capacity setting set 133. If the swivel unit 130 is turned with the workpiece gripping device 110 inserted into the substrate holding force set 100, the substrate holding force set 100 and the workpiece gripping device 110 interfere with each other. Rotate and move the arm in the negative direction of the X-axis until the board capacity setting set 100 and workpiece gripping device 110 do not interfere. Next, the turning shaft motor 128 is rotated to rotate the turning shaft 130 and the turning portion 129 is turned. Since the first arm shaft 114 is supported by the turning portion 129, each portion connected from the first arm shaft 114 to the work gripping device 110 also turns together. FIG. 14 is a view in which the arm is contracted by the above-described operation, the turning portion 129 is turned, and the workpiece gripping device 110 is directed toward the board accommodation force set 133. Here, if the first arm shaft 114 is rotated, the workpiece gripping device 110 is rotated in the negative swing direction 132, and the arm is moved in the negative Y-axis direction to the board holding force set 133, the workpiece is held in the board holding force set 133. Device 110 can be inserted.

FIGS. 15 to 16 show a state in which the glass substrate 107 is transported and inserted into an arbitrary substrate capacity set 100 of the substrate capacity sets 100 in which a plurality of robots 102 are stacked. In many cases, a plurality of substrate capacity sets 100 are stacked in order to accommodate more glass substrates 107 in a limited area. If the stacked board capacity set 100 is counted as one stage from the bottom, two stages and one n stage, the board capacity set is placed above the nth board capacity set 135, for example, the second stage. The board capacity set is n + second stage board capacity set 136. In FIG. 15, the robot 102 is in a state where the arm gripping device 110 can be inserted into the nth-stage substrate capacity setting set 135 by performing an operation of extending the arm. Thus, when inserting the workpiece gripping device 110 into the n + second stage substrate storage cassette 136, the elevator shaft motor 124 is rotated, the elevator installation part 125 and the elevator support part 126 are rotated, and the n + second stage substrate is inserted. It moves to the Z-axis direction position where the workpiece gripping device 110 can be inserted into the holding force set 136 (see Fig. 16). After moving in the positive direction of the Z-axis, the first arm shaft 114 is rotated to extend the arm, and the workpiece gripping device 110 is inserted into the n + second-stage board capacity setting set 136. FIG. 16 shows a state after the glass substrate is transferred and inserted into the N + second stage substrate capacity set with respect to the substrate capacity set in which a plurality of robots are stacked in the state of FIG. [0011] In the robot 102 configured as described above, the arm (first arm link 108, second arm link 109) is cantilevered with respect to the main body arm support 113, so that the weight of the arm and the workpiece grip Under the influence of the weight of the device 110 and the glass substrate 107, the arm stagnates in the direction of gravity. With the recent increase in the size of glass substrates, this stagnation has increased due to the weight of the glass substrate and the size of the workpiece gripping device and arm corresponding to this, and the glass substrate contained in the substrate capacity setting set. In order to insert the robot's workpiece gripping device accurately and quickly during this period, and to extend and contract the arm without any interference with the glass substrate gripped by the workpiece gripping device, ), A technology that corrects the lead in the straight direction opposite to itch is disclosed (see Patent Document 1).

Thus, the conventional workpiece transfer device corrects the stagnation due to gravity of the glass substrate, the arm, and the workpiece gripping device.

Patent Document 1: Japanese Patent Laid-Open No. 2000-183128

Disclosure of the invention

Problems to be solved by the invention

[0012] The conventional workpiece transfer device described in Patent Document 1 corrects static stagnation due to the gravity of the substrate and the arm. However, many robots produce a stagnation that is larger than a static sag due to the moment of inertia that is applied when the arm extends or contracts.

The manner in which the moment of inertia is generated during arm expansion and contraction will be described with reference to Figs. Figure 17 shows the shape of the center of gravity when the robot grips the glass substrate on the workpiece gripping device. M represents the center of gravity including the workpiece gripping device 110 and the glass substrate 107, and the weight is m [kg]. Xg represents the distance in the X-axis direction from the arm shaft motor 115 to the center of gravity M, and Zg represents the distance in the Z-axis direction from the arm shaft motor 115 to the center of gravity M. FIG. 18 shows the relationship between the arm shaft motor 115 and the center of gravity M in FIG. 17 as a simple model. As the arm shaft motor 115 rotates, the translation force F1 [N] is generated when the arm moves in the positive direction of the X axis at an acceleration a [m / s ² ]. F1 is determined by equation (3),

F1 = ηι · a… ό)

It becomes. F2 shows the translational force due to the reaction that the center of gravity receives by Fl. F1 and F2 are in the relationship of equation (4). F1 = F2 (4)

The arm shaft motor shaft center position 137 indicates the center position of the arm shaft motor 115, N indicates the moment of inertia N [Nm] generated around the arm shaft motor shaft center position 137 by F2, and is obtained by equation (5). .

N = F2-Zg (5)

[0013] It is ideal that each part of the robot arm and the workpiece gripping device are close to a perfect rigid body! In many cases, the strength of the member is reduced in order to reduce the load and the cost. It has a certain degree of rigidity! /, But it is close to a perfect rigid body! / Unless it is almost a perfect rigid body, the moment of inertia N causes stagnation in each arm part and workpiece gripping device.

Figure 19 shows the stagnation of each part of the arm and the workpiece gripping device when the arm is extended in the positive direction of the X axis. As explained with reference to FIG. 18, the moment of inertia is applied counterclockwise in the figure around the first arm axis 114. The first arm link 108 swung counterclockwise in the figure due to the moment of inertia. The second arm shaft 118 is deviated counterclockwise in the figure around the first arm shaft 114 from the position when it is a complete rigid body. The second arm link 109 is swung counterclockwise around the second arm shaft 118 by the moment of inertia. The flange 122 deviates counterclockwise in the figure around the second arm shaft 118 from the position when it is a complete rigid body. The workpiece gripping device 110 is swung counterclockwise around the flange 122 by the moment of inertia. The ideal control point 139 shows the control point position when the arm is a perfect rigid body, but the position of the center of gravity is stagnated due to the influence of the above moment of inertia, and as a result the control point is also shifted The position indicated by control point 138 Thus, the amount of deviation in the Z-axis direction is ΔΖ1.

FIG. 20 shows a simple model of the relationship between the arm shaft motor 115 and the center of gravity M shown in FIG. 17, and the translational force F3 [N] when the X axis negative direction is contracted with acceleration a [m / s ² ]. This shows how this occurred. The translational force F3 is obtained by equation (6) as in equation (3).

F3 = m 'a… (6)

It becomes. F4 shows the translational force due to the reaction that the center of gravity receives by F3. F3 and F4 are in the relationship of equation (7).

F3 = F4 (7) The arm shaft motor shaft center position 137 indicates the center position of the arm shaft motor 115, N indicates the moment of inertia N [Nm] generated around the arm shaft motor shaft center position 137 by F4, and is obtained by equation (8). .

N = F4 -Zg (8)

FIG. 21 shows the stagnation of each part of the arm and the workpiece gripping device when the arm is contracted in the negative X-axis direction. As described with reference to FIG. 20, the moment of inertia is applied clockwise with the first arm shaft 114 as the center. The first arm link 108 crawls clockwise in the figure due to the moment of inertia. The second arm shaft 118 is deviated clockwise from the position of the complete rigid body around the first arm shaft 114 in the drawing. The second arm link 109 is swung clockwise around the second arm shaft 118 by the moment of inertia. The flange 122 is deviated clockwise from the position of the complete rigid body around the second arm shaft 118 in the drawing. The workpiece gripping device 110 is pinched clockwise around the flange 122 by the moment of inertia. The ideal control point 139 is the force indicating the control point position when the arm is a perfect rigid body, and the center of gravity position is stagnated due to the influence of the above inertial moment, and as a result, the control point 140 is also shifted. The Z axis displacement is Δ Δ2.

FIG. 22 shows the relationship between the speed of the arm axis motor and the amount of stagnation of the control point position and time when the robot moves the arm in the positive direction of the X axis. The horizontal axis t indicates time, the vertical axis V indicates speed, and the vertical axis Z indicates the amount of stagnation in the Z-axis direction at the control point position. When the robot moves the arm in the positive direction of the X axis, the arm axis motor has the speed waveform indicated by the arm axis motor speed 143. When the arm accelerates in the X-axis positive direction, the arm-axis motor 115 accelerates as indicated by the arm-axis motor speed 143, the moment of inertia is generated as described above, and the control point is shifted in the Z-axis positive direction. The amount of shift over time at this time is shown as the amount of stagnation 144 in the control point position during acceleration. When the arm decelerates from the steady speed in the positive direction of the X axis, the arm shaft motor 115 decelerates from the steady speed as indicated by the arm shaft motor speed 143, the inertia moment is generated as described above, and the control point is Shifts in the negative Z-axis direction. The amount of shift over time at this time is shown in Stagnation amount 145 of control point position during deceleration.

[0017] Due to the sag of the arm that occurs due to the above reasons, the workpiece gripping device of the robot is put in and out of the substrate stored in the substrate capacity setting and is gripped by the workpiece gripping device. When the substrate is taken in and out, and when the substrate is taken in and out of the processing unit, interference occurs in each part, and the substrate and the like may be damaged. As measures against this, it is possible to increase the space between the substrates in the board capacity set and to reduce the acceleration / deceleration speed of the arm to reduce the moment of inertia. There are adverse effects such as a decrease in the number of sheets and the time required for substrate transfer. It is also possible to create an operation program that controls the robot's operation in advance so that it does not interfere with the substrate capacity setting and the substrate processing unit due to the sag of the arm when it is extended and contracted. Since the sag when the force arm extends and contracts depends on the weight of the workpiece gripping device and the gripped glass substrate and the position of the center of gravity, all the motion programs created when the workpiece gripping device and the gripping glass substrate are changed must be recreated. There must be. In recent years, glass substrates have become larger in size, and demand for liquid crystal displays is increasing, so production is required more quickly, and this stagnation tends to increase.

[0018] The present invention has been made in view of such problems, and includes a substrate capacity setting without lowering the acceleration / deceleration speed of the arm's expansion / contraction operation, and the insertion / extraction of the glass substrate into / from the processing portion of the substrate. An object of the present invention is to provide a robot apparatus that can be used without interference. Means for solving the problem

In order to solve the above problems, the present invention is configured as follows.

The invention described in claim 1 includes an arm having a workpiece gripping device for gripping or placing a workpiece at a tip thereof, an arm shaft motor that extends and contracts the arm in a horizontal direction, and a lifting shaft motor that lifts and lowers the arm. And a workpiece transfer device comprising a control device that drives and controls the arm axis motor and the lifting axis motor of the robot, and the arm when the arm is extended and contracted by driving the arm axis motor. And the workpiece gripping device or the arm, the workpiece gripping device, and the inertia moment based on the horizontal movement acceleration / deceleration of the workpiece, the amount of vertical stagnation of the control point position of the robot is obtained. It is characterized by having correction means for driving and correcting in the vertical direction.

According to a second aspect of the present invention, the control device includes storage means, and the robot mouth bot information, the workpiece gripping device information of the workpiece gripping device, and the workpiece information of the workpiece in advance. Information and other parameters are registered, and the amount of stagnation is obtained based on the parameters.

According to the invention of claim 3, when a gripping device identifier is assigned to each of the plurality of workpiece gripping devices, the workpiece gripping device information is registered in association with the gripping device identifier, and when the amount of stagnation is obtained, The amount of stagnation is obtained based on the workpiece gripping device information searched by the gripping device identifier.

In the invention according to claim 4, a work identifier is assigned to each of the plurality of works, the work information is registered in association with the work identifier, and when the amount of stagnation is obtained, the work identifier is searched. The amount of stagnation is obtained based on work information.

The invention according to claim 5 is characterized in that the robot is a horizontal articulated robot for transporting a liquid crystal glass substrate.

The invention's effect

[0020] With the above configuration, the control device of the present invention calculates the sag of the arm due to the moment of inertia when the robot having the arm and the lifting shaft expands and contracts, and the control point position shifts due to the sag. By correcting the amount by moving the lifting axis in the Z-axis direction, the vertical trajectory of the control point can be kept constant.

Brief Description of Drawings

[0021] FIG. 1 is a flowchart of the present invention.

[Figure 2] Stagnation angle when the arm is moved in the positive direction of the X axis φ 1

[Figure 3] Stagnation angle φ 2 when the arm is moved in the negative direction of the X-axis

[Figure 4] Relationship between arm axis motor speed, control point position, correction amount, and time when the arm is moved in the positive direction of the X axis

[Fig.5] Correction of the amount of sag ΔZ when the arm is accelerated in the positive direction of the X axis

[Fig.6] Correction of the amount of sag ΔZ when the arm is accelerated in the negative direction of the X axis

[Fig.7] Configuration of work transfer device

[Figure 8] Robot configuration diagram

[Fig.9] Robot arm extended [Figure 10] Diagram of robot arm contracted

11] A state diagram of the robot going up and down

[Figure 12] Configuration view from the top of the robot

13] Positional relationship diagram with the robot that expands and contracts to the X direction board capacity set

14] Positional relationship with the robot that expands and contracts to the Y direction board capacity set

Fig. 15] Before inserting the workpiece gripping device into the η stage of multiple substrate capacity sets. 16) Inserting the workpiece gripping device into the η + 2 stage of multiple substrate capacity sets. 17] Schematic diagram of the center of gravity when a glass substrate is gripped by a workpiece gripping device

[Figure 18] Model of moment of inertia when the arm is moved in the positive direction of the X axis

[Figure 19] Diagram of stagnation when the arm is moved in the positive direction of the X axis

[Fig.20] Model of moment of inertia when arm is moved in the negative X-axis direction

[Fig.21] Stagnation when arm is moved in the negative X-axis direction

[Fig.22] Relationship between speed and control point position stagnation amount and time of arm axis motor when arm is moved in X axis positive direction

Explanation of symbols

13 Temporal change in correction amount when the arm is accelerated in the X-axis positive direction

14 Temporal change in correction amount when arm is decelerated in the X-axis positive direction

15 Corrected control points when the arm is accelerated in the positive direction of the X axis

16 Corrected control points when the arm is decelerated in the positive direction of the X axis

100 board capacity set

101 Support pin

102 robot

103 cable

104 Control device

105 Cape Nore

106 Teaching means

107 Glass substrate

108 1st arm link 109 Second arm link

110 Work gripping device

111 Upper lifting link

112 Lower lift link

113 Main arm support

114 First arm shaft

115 Arm shaft motor

116 Arm shaft reducer

117 1st link belt

118 Second arm shaft

119 Second arm shaft reducer

120 2nd link belt

121 flange reducer

122 Flange

123 Control point

124 Lifting shaft motor

125 Lifting installation

126 Lifting support

127 Z-axis zero reference

128 slewing axis motor

129 Turning part

130 Rotating axis

131 Turning positive direction

132 Turning negative direction

133 Substrate capacity set

134 Support pin

135 nth stage board capacity set

136 n + second stage board capacity set 137 Arm shaft Motor shaft center position

138 Misaligned control point (when the arm accelerates in the positive direction of the X axis)

139 Ideal control point

140 Deviated control point (when the arm accelerates in the negative direction of the X axis)

141 Ideal center of gravity

142 Center of gravity shifted

143 Arm shaft motor speed

144 Sag amount of control point position during acceleration

145 Sag amount at control point position during deceleration

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0024] (First embodiment)

A workpiece transfer device that applies the present invention to a horizontal articulated mouth bot having a vertical lifting shaft having the configuration shown in FIGS. 7 and 8 will be described.

The parameters of the robot 102 are input in advance to storage means (not shown) provided in the control device 104. The storage means includes a distance [m] from the first arm shaft 114 to the second arm shaft 118, a distance [m] from the second arm shaft 118 to the flange 122, and an arm shaft motor 115 to the flange 122 shown in FIG. Z-axis direction distance up to [m], the distance [m] from the lifting installation part 125 to the lifting axis motor 1 24, and the distance from the lifting axis motor 124 to the lifting support part 126 [m] Weight of gripping device [kg], X-axis direction distance [m] from workpiece gripping device flange 122 to workpiece center of gravity M, Z-axis direction distance [m] from workpiece gripping device flange 122 to workpiece weight M, workpiece X-axis direction distance [m] from gripping device flange 122 to control point, Y-axis direction distance [m] from workpiece gripping device flange 122 to control point, and Z from workpiece gripping device flange 122 to control point The workpiece gripper information, which is the axial distance [m], and the workpiece to be gripped Amount [kg], distance in the X-axis direction from the flange 122 of the workpiece control point to the workpiece center of gravity M [m], and distance in the Z-axis direction from the flange 122 of the workpiece control point to the workpiece center of gravity M [ m] workpiece information, stiffness value K [Nm / rad] between the arm and the workpiece gripping device, and the control device sends an operation command to each motor. Register the parameters of the command cycle time [s] of the output control cycle.

[0025] When there are a plurality of types of workpiece gripping devices or workpieces, identifiers (gripping device identifiers, workpiece identifiers) such as unique numbers are assigned to each, and the aforementioned parameters are registered for each identifier. These parameters are searched by the force identifier used for calculation during operation.

The various parameters are stored in the storage means of the control device 104 via a force input by pressing a button provided on the teaching means 106, communication means from an external storage device (not shown). It should be noted that force S, which requires other parameters for the desired operation and control of the workpiece transfer device, is omitted because it is not related to the present invention.

The robot 102 inputs an operation command to the control device 104 via the cable 105 in accordance with an operation program stored in the storage means in advance or by pressing a plurality of buttons provided in the teaching means 106, and the cable 103 It operates by giving to each motor via.

The operation of a robot composed of a plurality of axes to which the present invention is applied will be described with reference to the flowchart of FIG.

The operation program describes the number (identifier) of the workpiece gripping device provided during operation and the number (identifier) of the workpiece being gripped. First, the work program is selected in preparation for the operation of reproducing the designated operation program, and a parameter referred to by an identifier included in the work program is retrieved and read.

On the other hand, in the teaching mode in which the robot 102 is operated by operating the teaching means, when the operation command is input to the control device 104 via the cable 105 by pressing the button provided on the teaching means 106, the workpiece gripping device provided. The identifier (number) of the robot and the identifier (number) of the workpiece gripped during operation are transmitted.

[0028] The distance in the X-axis direction [m] from the flange 122 to the workpiece center of gravity M and the distance in the Z-axis direction [m] are the distance in the X-axis direction from the workpiece gripper flange 122 to the workpiece center of gravity M The distance [m], the Z-axis direction distance [m] from the workpiece gripping device flange 122 to the workpiece center of gravity M in operation, and the X axis from the workpiece flange 122 to the workpiece center of gravity M in operation It can be obtained using the direction distance [m] and the Z-axis direction distance [m] from the flange 122 of the workpiece gripped during operation to the center of gravity M of the workpiece. The X-axis direction distance from the first arm shaft 114 to the flange 122 after giving an operation command for one predetermined control cycle from the controller to each motor is the first arm stored in the storage means in advance. It can be obtained geometrically using the distance [m] from the axis 114 to the second arm axis 118 and the distance [m] from the second arm axis 118 to the flange 122. For example, in the case of an arm having the mechanism shown in FIGS. 8, 9, and 10, the distance in the X-axis direction from the first arm shaft 114 to the flange 122 is obtained by the equation (1) as described above. In addition, since the first arm shaft 114 and the arm shaft motor 115 are arranged at the same position in the X-axis direction, the first arm shaft 1 14 force and the X-axis direction distance [m] to the flange 122 are It is equal to the distance [m] in the X-axis direction from the shaft motor 115 to the flange 12 2.

[0029] (Step 1) Add the X-axis direction distance [m] from the flange 122 to the workpiece center of gravity M and the X-axis direction distance [m] from the arm axis motor 115 to the flange 122. The X-axis direction distance [m] from the arm shaft motor 115 to the workpiece center of gravity M after giving an operation command for one cycle, and the Z-axis direction distance [m] from the flange 122 to the workpiece center of gravity M and the storage means Calculate the distance [m] in the Z-axis direction from the stored arm axis motor 115 to the flange 122, and give an operation command for one cycle from the controller to each motor. From arm axis motor 11 5 to workpiece center of gravity M Find the distance [m] in the Z-axis direction.

(Step 2) The distance in the X-axis direction from the first arm shaft 114 to the flange 122 before giving an operation command for one cycle from the controller to each motor is the first arm shaft 114 stored in the storage means in advance. Can be obtained geometrically using the distance [m] from the second arm shaft 118 to the second arm shaft 118 and the distance [m] from the second arm shaft 118 to the flange 122. For example, in the case of an arm having the mechanism shown in FIGS. 8, 9, and 10, the distance in the X-axis direction from the first arm shaft 114 to the flange 122 is obtained by the equation (1) as described above.

From the above, the X-axis direction distance [m] from the flange 122 to the workpiece center of gravity M and the X-axis direction distance [m] from the arm shaft motor 115 to the flange 122 are added, and one cycle of operation from the controller to each motor. Obtain the distance [m] in the X-axis direction from the arm shaft motor 115 before giving the command to the workpiece center of gravity M

(Step 3) The difference in the X-axis direction distance from the arm shaft motor 115 obtained in Step 1 and Step 2 to the workpiece center of gravity M is calculated. In other words, the X axis movement distance of the workpiece center of gravity Ask.

[0032] (Step 4) By dividing the movement distance in the X-axis direction of the center of gravity obtained in Step 3 by the square of the periodic time [s] for which the control device previously stored in the storage means outputs the operation command to each motor. Acceleration / deceleration a [m / s ² ] is calculated.

[0033] (Step 5) Add the weight [kg] of the workpiece gripping device registered in the control device! /, And the weight [kg] of the workpiece gripping device in operation. Then, the total weight of the tip portion is obtained from the flange 122, and the translational force F [N] is obtained from the acceleration / deceleration a [m / s ² ] obtained in step 4 by the equation (9).

F = m 'a… (9)

[0034] (Step 6) The Z-axis direction distance [m] from the arm shaft motor 115 to the center of gravity M after giving an operation command for one cycle from the control device obtained in Step 1 to each motor. Using the reaction force of the translational force F [N] obtained (the value is equal to the translational force F), obtain the moment of inertia N [Nm] using Equation (10).

N = F-Zg (10)

[0035] (Step 7) Using the stiffness value K [Nm / rad] applied to the workpiece gripping device gripped during operation and the moment of inertia N [Nm] obtained in Step 6, it is possible to Find the angle φ [rad].

φ = N / K (11)

The required stagnation angle φ is illustrated by FIGS. Figure 2 shows the stagnation angle φ 1 when the arm is moved in the positive direction of the X axis. Figure 3 shows the stagnation angle Φ 2 when the arm is moved in the negative direction of the X axis. When the point of intersection between the turning center line of the first arm axis 114 and a straight line that passes through the control points when each part of the arm and the workpiece gripping device 110 are completely rigid and is parallel to the workpiece gripping device 110 is P Each angle is an angle formed by a straight line that passes through the point P and the control point, and a straight line that connects the control point 138 and the point P that are displaced by the gripping of each part of the arm and the workpiece gripping device 110.

The stagnation angle φ is also defined as point P when the intersection point of each arm part and a straight line passing through the center of gravity and parallel to the work gripping device 110 when the work gripping device 110 is a complete rigid body is point P. When the straight line passing through the center of gravity position 141, the arm parts, and the workpiece gripping device 110 It is equal to the angle formed by the straight line connecting the displaced center of gravity 142 and point P.

[0036] (Step 8) The distance [m] from the first arm axis 114 to the second arm axis 118, the distance [m] from the second arm axis 118 to the flange 122 stored in the storage means in advance, and the arm axis Using the angle of the motor 115, geometrically determine the distance in the X-axis direction (arm expansion / contraction length) from the first arm shaft 114 to the flange 122 after giving an operation command for one cycle from the controller to each motor. . For example, in the case of an arm having the mechanism shown in FIGS. 8, 9, and 10, the distance in the X-axis direction from the first arm shaft 114 to the flange 122 is obtained by the equation (1) as described above.

[0037] (Step 9) The distance from the first arm axis 114 to the control point by adding the arm expansion / contraction length obtained in Step 8 and the X-axis direction distance [m] from the flange 122 of the workpiece gripping device to the control point Find R [m] and use the stagnation angle φ [rad] found in step 7 to find the stagnation amount AZ [m]. The amount of stagnation A Z [m] is obtained by equation (12).

A Z = Rsin ((i)) (12)

[0038] (Step 10) Assuming that each part of the arm is a complete rigid body, geometrically obtain the lift amount [m] of the lift shaft after giving an operation command for one cycle from the controller to each motor, The Z-axis direction distance [m] from the workpiece gripping device flange 122 to the control point is added to the lift [m], and the control point after the operation command for one cycle is given from the control device to each motor. Calculate the Z-axis direction position [m], subtract the stagnation amount AZ [m] obtained in Step 9, and use this as the corrected target control point Z-axis direction position Zc [m].

(Step 11) After giving an operation command for one cycle from the control device to each motor, the distance [m] from the lifting / lowering installation part 125 to the lifting / lowering axis motor 124 stored in the storage means in advance, Each motor of the lift shaft to operate with only the lift shaft to the target control point Z-axis direction position [m] corrected in step 10 using the distance [m] from the motor 124 to the lift support portion 126 Find the angle geometrically. For example, in the case of a lifting shaft equipped with the mechanism shown in FIG. 11, the distance [m] from the lifting mounting portion 125 to the lifting shaft motor 124 stored in the storage means in advance, and the distance from the lifting shaft motor 124 to the lifting support portion 126. If the distance [m] is equal, and b is the corrected target control point Z-axis direction position Zc [m], the lift shaft motor angle γ of the lift shaft is a modified formula (2) ( 13). γ = asin (Zc / 2b).

(Step 12) An operation command corresponding to the lifting axis motor angle γ obtained in Step 11 is newly output to each axis motor of the robot 102 via the cable 103 as an operation command to the lifting axis motor.

[0041] The operation command output to each motor over the course of the above processing takes the correction into account, and as a result, the target control point position is corrected. Fig. 4 shows the speed 143 of the arm axis motor when the robot shown in Fig. 22 moves the arm in the positive direction of the X axis, the relationship between the control point position and time, and the correction amount. The horizontal axis t indicates time, the vertical axis V indicates speed, and the vertical axis Z indicates the amount of stagnation 144, 145 in the Z-axis direction of the control point position. The correction amount is equal to that obtained by inverting the sign of the stagnation amount Δ obtained in step 9. The correction amount when the arm accelerates in the X-axis positive direction is correction 13 during acceleration, and the arm moves in the X-axis positive direction. The correction amount when decelerating is correction 14 when decelerating.

FIG. 5 shows a state in which the amount of sag Δ 補正 is corrected when the robot accelerates the arm in the positive direction of the X axis. The sum of the amount of stagnation Δ Ζ and the correction amount is zero, so the corrected control point 15 and the ideal control point 138 have the same Z-axis position, and the Z-axis position of the control point is kept constant. It is. Fig. 6 shows how the robot corrects the sag amount Δ Δ when the robot accelerates the arm in the negative direction of the X axis. Since the added value of the stagnation amount ΔΖ and the correction amount is zero, the corrected control point 16 and the ideal control point 139 have the same Z-axis position, and the control point Z-axis position is kept constant. Be drunk.

[0043] By executing this series of processing flows in the output cycle of the operation command of the control device, it is possible to always correct the stagnation due to the moment of inertia in the vertical direction. In addition, since this stagnation correction does not use complicated calculation as in the embodiment, the calculation time by the microcomputer provided in the control device for controlling the robot can be reduced, so that the robot motion control process Les, which can affect.

Also, if multiple glass substrates with different weights are mixed in multiple substrate capacity sets, prepare an operation program with different workpiece identifiers (numbers) to be gripped, and match the glass substrates to be gripped. By executing the operation program, the glass substrate can be transported without any stagnation due to the moment of inertia. [0044] The above is an example for carrying out the present invention. The arm is a linear motion shaft composed of, for example, a motor, a rack & pinion, or a ball screw, or a linear motion shaft powered by air pressure or hydraulic pressure by electromagnetic valve control. In addition, the first arm shaft 114, the second arm shaft 118, and the flange 122 are each equipped with a motor, and can be individually rotated to perform interpolation operation in the X-axis direction and operate in the Y-axis direction and the Z-axis direction. It may be possible. The arm has a mechanism that can linearly interpolate the glass substrate in the X-axis direction!

The lifting shaft is a linear motion shaft composed of, for example, a rack and pinion or a ball screw, a linear motion shaft powered by air pressure or hydraulic pressure controlled by a solenoid valve, and the lifting shaft motor 124 and the lifting support portion in addition to the lifting shaft motor 124. 126 may be equipped with a motor, rotate individually, perform interpolation in the Z-axis direction, and operate in the X-axis and Y-axis directions. The lift axis only needs to have a mechanism that can perform linear interpolation in the Z-axis direction. 7, 8, 12, 13, and 14 exemplify a general device. The force pivot 130 is not necessarily provided.

Further, the teaching means 106 shown in FIG. 7 may be a general-purpose computer or personal computer equipped with an external storage device, for example, the force teaching means 106 provided with an external storage device (not shown). If the operation program is stored in the storage means in advance, the teaching means 106 may not be provided. The cable 105 shown in FIG. 7 is shown as an electrically connected wired transmission means! /, A force that can be a wireless means using radio waves! /, For example.

[0045] Since the present invention can be applied to a robot having degrees of freedom in the horizontal direction and the vertical direction, it can be applied to, for example, a vertical 6-axis articulated robot used in many industrial robots. I can do it. For example, in handling between presses, a workpiece must be conveyed at high speed and accurately to a pressing machine that continues to operate. Since the work entrance of the press machine is the minimum size to carry the work, it is possible that the work and the press machine may interfere with each other due to the stagnation caused by the moment of inertia when transporting at high speed. However, if the present invention is applied, the amount of stagnation that occurs during the conveyance of the workpiece is calculated, and the calculated 橈 is the direction deviated by stagnation from the position where each part is a complete rigid body. The amount of stagnation can be eliminated linearly by linear interpolation using 6 degrees of freedom.

Industrial applicability The present invention is considered to generate dynamic stagnation due to a high-speed and long-stroke operation, and can be applied particularly to an operation in which one end is operated and a workpiece is conveyed at the other end.

Claims

The scope of the claims

[1] A robot provided with an arm having a workpiece gripping device at a tip for gripping or placing a workpiece, an arm shaft motor that extends and retracts the arm in a horizontal direction, and a lifting shaft motor that lifts and lowers the arm; In a workpiece transfer device including a control device for driving and controlling the arm shaft motor and the lifting shaft motor of the robot,

Control point position of the robot by the moment of inertia based on the horizontal movement acceleration / deceleration of the arm and the workpiece gripping device or the workpiece when the arm is extended and contracted by driving the arm shaft motor A workpiece conveying apparatus comprising: a correction unit that obtains the amount of stagnation in the vertical direction and corrects the amount of stagnation in the vertical direction by driving a lifting shaft.

[2] The control device includes storage means, and registers robot information of the robot, workpiece gripping device information of the workpiece gripping device, workpiece information of the workpiece, and other parameters in advance. 2. The work conveying apparatus according to claim 1, wherein the amount of stagnation is obtained based on the value.

[3] A gripping device identifier is assigned to each of the plurality of workpiece gripping devices, and the workpiece gripping device information is registered in association with the gripping device identifier. When the amount of stagnation is obtained, the gripping device identifier is searched. 3. The workpiece transfer device according to claim 1, wherein the amount of stagnation is obtained based on the workpiece gripping device information.

[4] A work identifier is assigned to each of the plurality of works, the work information is registered in association with the work identifier, and the amount of stagnation is obtained based on the work information retrieved by the work identifier. 3. The workpiece transfer device according to claim 1, wherein the amount of stagnation is obtained.

[5] The workpiece transfer apparatus according to claim 1, wherein the robot is a horizontal articulated robot for transferring a liquid crystal glass substrate.