JP2000183128A - Control device for work transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To move a work WK linearly along a horizontal line, by preventing the moving trajectory of the work from changing into a curve deflected in its self-weight direction when carrying the work by a carrying robot to the carry-in port of a load locking chamber. SOLUTION: A vertical-deflection quantity ΔZ of an arm is set by making it correspond to a horizontal-movement quantity X of the tip of the arm. Then, a vertical-deflection quantity ΔZ12 corresponding to a present horizontal- movement quantity X12 (P12) of the tip of the arm is determined from the set content in the above. Accordingly, a vertical-movement quantity Z (vertical drive command) is so corrected that the arm is moved by the above deflection quantity ΔZ12 in the opposite vertical direction to its deflection direction, and the vertically drive command is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work transfer device for transferring a work at the distal end of an arm by horizontally moving an arm supported at one end with respect to a base end, and in particular, it is possible to eliminate bending of the arm. It concerns the device.

[0002]

2. Description of the Related Art For example, in a semiconductor manufacturing system such as a glass substrate for a liquid crystal or a semiconductor wafer, unit processing units for manufacturing, film formation, heat treatment and the like are arranged at predetermined positions, and the substrates are sequentially placed on these unit processing units. By carrying the substrate, a series of treatments are performed on the substrate.

FIG. 3 shows an example of this type of semiconductor manufacturing system, and illustrates a manufacturing system for manufacturing a liquid crystal panel by performing a predetermined process on a glass substrate.

[0004] As shown in FIG.
A plurality of storage cassettes (cassette magazines) C
And a plurality of glass substrates are accommodated in these accommodation cassettes C in a stepped manner.

[0005] The processing chamber 21 in FIG.
It is kept to a high degree of cleanliness. The processing chamber 21 includes a transfer chamber TC and a plurality of process chambers PC1 and PC provided around the transfer chamber TC and serving as the unit processing units described above.
2, PC3, PC4 and PC5, and a pair of load lock chambers 22 and 23 as a vacuum preparatory chamber. The processing chamber 21 is disposed adjacent to the clean room CR via the load lock chambers 22 and 23.

FIG. 5 shows the load lock chamber 22 (23).
Is a side view, and a gate 3 is provided between the load lock chambers 22 and 23 and the clean room CR. This gate 3 is made of a glass substrate (hereinafter referred to as “work” as appropriate).
) Is opened via the open / close door 22c only when the WK is carried in / out. In a normal state, the gate 3 is closed by the opening / closing door 22c, and the above-described processing chamber 21 is maintained in a high vacuum, high temperature, and high clean state.

Inside the clean room CR and the transfer chamber TC, there are provided work transfer robots R1 and R2 as work transfer devices, respectively.

[0008] The work transfer robot R1 provided in the clean room CR includes a storage cassette C (supply cassette).
Is transferred to the load lock chamber 22 serving as an entrance to the transfer chamber TC, and the work WK in the load lock chamber 23 serving as an exit from the transfer chamber TC is transferred to the storage cassette C (storage-side cassette). It is a robot to make it.

The work transfer robot R2 provided in the transfer chamber TC transfers the work WK carried into the load lock chamber 22 to a plurality of process chambers PC1, PC2.
… And then sequentially transferred to these process chambers PC
1, a robot for transferring the work WK, for which a series of processes has been completed in PC2, to the load lock chamber 23.

In this type of manufacturing system, a work transfer robot having the structure shown in FIGS. 1 and 2 is applied. The work transfer robot R1 provided in the clean room CR will be described as an example.

FIG. 1 is a side view of the work transfer robot R1, and FIG. 2 is a top view thereof.

As shown in these figures, the work transfer robot R1 has a swing arm 16 and a second arm 17 as first arms with respect to a base B, which are vertically movable via a vertical shaft 11. I have. The base end of the turning arm 16 is supported rotatably about the turning shaft 12. Swivel arm 16
A base end of the second arm 17 is rotatably supported around the second shaft 13 at the distal end of the second arm 17. Further, a hand H is supported at the distal end of the second arm 17 so as to be rotatable around the wrist axis 14. The work WK is placed and held on the hand H. Thus, the work transfer robot R1 is
The arms 16 and 17 are cantilevered with respect to a base B (vertical shaft 11) which is a base end of the arm.

When the turning shaft 12 and the second shaft 13 as horizontal driving shafts are driven in accordance with the driving command, the amount of horizontal movement of the arm tip (work WK) with respect to the base B changes. This situation is shown in FIGS. 4 (a) and 4 (b). In addition, the vertical movement amount of the arms 16 and 17 is changed by driving the vertical shaft 11 as a vertical drive shaft according to the drive command. As a result, the work WK at the tip of the arm is transported to a position according to the drive command.

[0014]

As described above, in the work transfer robot R1 having the structure in which the arms 16 and 17 are cantilevered with respect to the base end of the arm, the arms 16, 1
Due to the influence of the weight of the work 7 and the weight of the work WK, the arms 16 and 17 are bent in the direction of their own weight from the original state shown by the solid line to the state shown by the broken line as shown in FIG. That is, at the arm tip (work WK), the arm 17 is bent in the vertical direction by the amount of bending of ΔZ. In particular, with the recent increase in the size of the substrate, the amount of deflection has become a size that cannot be ignored.

For this reason, when the arms 16 and 17 are extended with respect to the base end of the arm while holding the work WK, the movement trajectory of the work WK does not become a horizontal straight line when viewed from the side, but is caused by its own weight due to bending. The curve is shifted in the direction.

Here, the load lock chamber 22 shown in FIG.
As described above, it is integrated with the processing chamber 21 requiring high vacuum, high temperature and high cleanliness. Therefore, in order to minimize contamination and temperature gradients caused by contact with the outside air, the work WK and the hand H holding the work WK pass through the carry-in port 22a of the load lock chamber 22 (the carry-out port in the case of the load lock chamber 23). It must be as small as possible. That is, the vertical height of the carry-in entrance 22a needs to be minimum.

However, when the workpiece WK is transported to the loading port 22a of the load lock chamber 22 by the workpiece transport robot R1 and the movement trajectory of the workpiece WK is displaced in the direction of its own weight, the following problem occurs. I do.

(1) As shown in FIG. 5, the load lock chamber 2
The second entrance 22a and the work table 22b in the load lock chamber 22 are installed substantially linearly. However, even if the work WK is to be carried in linearly by the work transfer robot R1, if the second arm 17 is bent in the direction of its own weight, the work WK interferes with each part of the carry-in port 22a and the work table 22b, and the work WK is disturbed. There is a risk of damage.

(2) When the size of the workpiece WK to be transported becomes large, when the tip of the workpiece of the workpiece transport robot R1 hangs over the entrance of the storage cassette C (relatively, the arms 16 and 1).
7 is small) and when the tip of the work reaches the back of the storage cassette C (relatively, the arm 16,
17 is large), which cannot be ignored with respect to the vertical pitch of the cassette. For this reason, it is necessary to take sufficient clearance, and as a result, the vertical pitch of the storage cassette C must be increased. As a result, the number of work pieces accommodated in the accommodation cassette C decreases.

(3) Arm 1 of work transfer robot R1
It is possible to make the workpiece transfer locus close to a horizontal linear locus when viewed from the side by improving the rigidity of 6, 17. However, the weight and size of the arms 16 and 17 increase as the arm rigidity is improved. For this reason, driving the work transfer robot R1 requires a larger driving force, resulting in high cost. In addition, as the size of the second arm 17 increases, the carry-in port 22a of the load lock chamber 22 needs to be correspondingly enlarged, and the contact area with the outside air at the time of carry-in increases accordingly. This causes contamination of the processing chamber 21 and an increase in temperature gradient.

An object of the present invention is to solve these problems (1), (2) and (3).

Japanese Patent Application Laid-Open No. 7-99225 discloses an invention for solving the problems associated with the bending of the hand. However, the invention described in this publication corrects the deflection of the substrate accompanying the deflection of the hand by providing a dedicated hand mechanism.

An object of the present invention is to correct deflection without providing a dedicated hand mechanism.

Further, Japanese Patent No. 2575717 discloses an invention in which the problem of eliminating a positional shift when a substrate is carried in and out of a cassette is solved. However, the invention described in this publication is to dispose a sensor on the arm and detect the end of the substrate to correct the displacement.

An object of the present invention is to correct the deflection without providing a sensor on the arm.

[0026]

Therefore, according to a first aspect of the present invention, there is provided an arm supported at a cantilever position with respect to a base end, and the arm tip is moved horizontally by an amount corresponding to a drive command. A horizontal drive shaft that moves horizontally with respect to the end,
A vertical drive shaft for vertically moving the arm by a vertical movement amount according to the drive command, and controlling the transfer of the work at the tip of the arm by generating the drive command and outputting it to the horizontal drive shaft and the vertical drive shaft A control unit for controlling the work transfer device, the control unit comprising: a bending amount setting unit configured to set a vertical bending amount of the arm in association with the horizontal movement amount of the arm tip; The amount of bending corresponding to the current horizontal movement amount of the arm tip is obtained from the setting contents of the bending amount setting means, and the vertical movement is performed so that the arm vertically moves in the vertical direction opposite to the bending direction by the bending amount. The drive command is output after correcting the amount.

The first invention will be described with reference to FIGS.

As shown in FIGS. 11 and 12 (d), the arm 1 is associated with the horizontal movement amount X of the tips of the arms 16 and 17.
The amount of vertical deflection ΔZ of 6, 6 is set as line L6.

Then, as shown in FIGS. 11 and 12 (f), the current horizontal movement amount of the tip of the arms 16, 17 such as X
The flexure amount ΔZ12 corresponding to 12 (P12) is obtained from the above set contents. Then, the vertical movement amount (vertical drive command) Z is corrected so that the arms 16, 17 move vertically in the vertical direction opposite to the bending direction by the bending amount ΔZ12, and the drive command is output.

In a second aspect based on the first aspect, the control means outputs the drive command at each sampling time so that the tip of the arm follows a desired trajectory from a command start position to a target position. A bending amount corresponding to the horizontal movement amount of the tip of the arm at the current sampling time is obtained from the setting of the bending amount setting means, and the arm is vertically moved by the bending amount in a vertical direction opposite to the bending direction. The vertical movement amount is corrected so as to move, and a drive command at the current sampling time is output.

The second invention will be described with reference to FIGS.

As shown in FIGS. 11 and 12 (d), the arm 1 is associated with the horizontal movement amount X of the tips of the arms 16 and 17.
The amount of vertical deflection ΔZ of 6, 6 is set as line L6.

Then, as shown in FIG. 11 and FIG. 12 (f), the amount of deflection ΔZ12 corresponding to the horizontal movement amount of the tip of the arm 16, 17 at the current sampling time, for example, X12 (P12) is obtained from the above set contents. . Then, the vertical movement amount (vertical drive command) Z is corrected so that the arms 16, 17 move vertically in the vertical direction opposite to the bending direction by the bending amount ΔZ12, and the drive command at the current sampling time is output. .

According to a third aspect of the present invention, in the first aspect, the control means is a control means for outputting the drive command so that the tip of the arm sequentially reaches each target position. The relationship between the drive amount of the vertical drive shaft with respect to the drive amount of the horizontal drive shaft when the arm tip moves between the respective target positions, and the relationship of the amount of vertical deflection of the arm with respect to the horizontal movement amount of the arm tip The control means obtains a bending amount corresponding to the horizontal movement amount of the arm tip at the next target position from the setting contents of the bending amount setting means, and sets the arm in the opposite direction to the bending direction. The drive command is output after correcting the vertical movement amount so as to vertically move by the bending amount in the vertical direction.

The third invention will be described with reference to FIGS.

As shown in FIGS. 10, 13 (a) and 13 (b), the vertical drive shaft is moved with respect to the drive amount J2 of the horizontal drive shaft when the tips of the arms 16, 17 move between the target positions P1, P2. The relationship of the drive amount ΔZ (ΔZ = a · J2 + b) indicates that the arm 16
17 (line L1).

Then, as shown in FIGS. 10 and 13 (c), the bending amount ΔZ2 corresponding to the horizontal movement amount J22 (P2) of the tips of the arms 16 and 17 at the next target position P2 is obtained from the above set contents. . And arms 16, 17
The vertical movement amount (vertical drive command) Z is corrected so that the vertical movement by the bending amount ΔZ2 in the vertical direction opposite to the bending direction, and the drive command is output.

In a fourth aspect based on the first aspect, the bending amount setting means sets the bending amount in accordance with the type of the arm or the type of the work.
As a result, even when the weight of the arms 16 and 17 changes or the weight of the work WK changes, an accurate bending amount can be obtained.

As described above, according to the present invention, the arm 1
Since the drive commands in which the vertical movement amount (vertical drive command) Z is corrected so that the vertical movements 6 and 17 move in the vertical direction opposite to the bending direction by the bending amount ΔZ, the work WK moves. The work WK is moved linearly in the horizontal direction by preventing the trajectory from becoming a curve shifted in the direction of its own weight. Therefore, the above problems (1), (2), and (3) are solved.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control device for a work transfer device according to the present invention will be described below with reference to the drawings.

In the present embodiment, a work transfer robot R which operates in the manufacturing system shown in FIG.
This will be described using 1 as an example. The description of FIG. 3 is as described above.

FIG. 1 is a side view (cross-sectional view) of the work transfer robot R1, and FIG. 2 is a top view thereof.

As shown in these figures, the work transfer robot R 1 is configured such that a turning arm 16 as a first arm and a second arm 17 with respect to a base B have a vertical axis Z through a vertical axis 11.
It is arranged to be able to move up and down in the direction of. The vertical shaft 11 is driven by a motor M1.

The base end of the turning arm 16 is supported rotatably about the turning shaft 12. The pivot 12 is a motor M2
Driven by

A base end of a second arm 17 is supported at the tip of the turning arm 16 so as to be rotatable around the second shaft 13. The second shaft 13 is driven by a motor M3.

Further, at the tip of the second arm 17,
The hand H is supported rotatably around the wrist axis 14. The wrist shaft 14 is driven by a motor M4.

The work WK is placed and held on the hand H.

As described above, the work transfer robot R1 includes the base B (the vertical shaft 1) in which the arms 16 and 17 are the base ends of the arms.
The structure is cantilevered with respect to 1).

The motors M2, M3
Is driven, and the turning shaft 12 and the second shaft 13 as horizontal driving shafts
Is driven. This changes the amount of horizontal movement of the tip of the arm (the rotation center 14 of the hand H) with respect to the base B.
That is, a distance X (hereinafter, this distance is referred to as an arm extension amount X) from the center of rotation of the turning arm 16 (the turning axis 12) to the center of rotation of the hand H (the wrist axis 14) changes.

As shown in FIG. 2, when the turning shaft 12 rotates in the direction of arrow A1 and the second shaft 13 rotates in the direction of arrow B1, the tips of the arms 16, 17 extend in the direction of arrow a1. When the turning shaft 12 rotates in the direction of arrow A2 and the second shaft 13 rotates in the direction of arrow B2, the tips of the arms 16 and 17 (the rotation center 14 of the hand H) contract in the direction of arrow a2.

The motor M1 is driven according to the drive command, and the vertical shaft 11 is driven as a vertical drive shaft. Thus, the vertical movement amount Z of the arms 16 and 17 in the Z-axis direction changes.

FIG. 7 shows the rotation angle J of the swing arm 16.
1, the geometric relationship between the rotation angle J2 of the second arm 17 and the amount X of arm extension is shown from above.

As shown in FIG. 7, the work transfer robot R1 has the length of the swing arm 16 (the swing shaft 12 and the second shaft 1).
3) and the length of the second arm 17 (the distance between the second shaft 13 and the wrist shaft 14), that is, the SCARA robot has a so-called link ratio of 1: 1.

At this time, it is assumed that the center of rotation of the hand H (wrist shaft 14) moves linearly along the X axis passing through the turning shaft 12. That is, the rotation center 14 of the hand H is
The rotation angle J1 of the turning arm 16 when it is located at 1 is J11, and the rotation angle J2 of the second arm 17 is J21. At this time, the horizontal line H of the rotation center 14 of the hand H
The amount of deflection ΔZ in the vertical direction with respect to L is defined as ΔZ1. The rotation angle J1 of the turning arm 16 when the rotation center 14 of the hand H is located at the target point P2 is set to J12,
The rotation angle J2 of the arm 17 is set to J22. Note that the deflection amount ΔZ of the rotation center 14 of the hand H at this time is set to ΔZ2. J1 is an angle with respect to the X axis, and is an angle that changes in the increasing direction. J2 is the angle of the second arm 17 with respect to the turning arm 16 and is an angle that changes in the decreasing direction.

Then, the rotation angle change amount Δ of the turning arm 16 is obtained.
The following relationship is established between J1 (= J12−J11) and the rotation angle change amount ΔJ2 (= J21−J22) of the second arm 17.

ΔJ2 = 2 · ΔJ1 (1) As a control method for causing the tip of the arm (the rotation center 14 of the hand H) of the work transfer robot R1 to reach the target point,
There are P (continuous path) control and PTP (point-to-point) control.

In the CP control, each drive shaft 11, 1 is moved so as to move along a desired locus between the target point P1 and the target point P2.
This is a control method for controlling the driving of the second and the third. The PTP control is performed so that each drive shaft 11,
This is a control method for controlling the drive of the motors 12 and 13 and the target point P1
This is a control method irrespective of the route through P2.

In the case of the PTP control, a drive command (speed command) for each of the drive shafts 11, 12, 13 is provided between the target points P1 and P2.
Of the drive shafts 11, 12, 13
Drive shafts 11, 12, 13 so that the operation times of
, A drive command is output.

Therefore, in the case of the PTP control, each drive shaft 1
A certain relationship is established between the drive amounts of 1, 12, and 13. As shown in FIG. 7, when the PTP control is applied to the SCARA robot R1 having the link ratio of 1: 1 and the fixed rotating shaft 12, the driving amount J2 of the horizontal driving shaft 13 (the second arm 1)
7 and the driving amount ΔZ of the vertical drive shaft 11 have the following relationship.

ΔZ = K · (1 + J2 / 180) (2) When this is generalized and expressed, it is as follows.

ΔZ = a · J2 + b (3) where a and b are constants. As described above, in the case of the PTP control, the drive amount ΔZ of the vertical drive shaft (vertical axis) 11 can be represented by a linear expression using the drive amount J2 of the horizontal drive shaft (second axis) 13 as a variable.

As described above, the workpiece transfer robot R1 is
Each drive shaft 11, 1 is controlled by P control or PTP control.
The work WK at the tip of the arm (the rotation center 14 of the hand H) is conveyed to the target positions P1 and P2 according to the drive command by controlling the driving of the units 2 and 13.

The work W is moved by the work transfer robot R1.
FIG. 4 shows how K is carried into load lock chamber 22.
(A) and (b) show.

The clean room CR as shown in FIG.
When the work WK is taken out of the accommodation cassette C of FIG.
The rotation shaft 12 is driven to rotate, and the hand H is positioned at a position facing the carry-in port 22 a of the load lock chamber 22. At this time, the distal ends of the arms 16 and 17 (the rotation center 14 of the hand H) are retracted toward the base end of the arm (the pivot 12).

Next, the turning shaft 12 and the second shaft 13 are driven to rotate, and the ends of the arms 16 and 17 (the rotation center 14 of the hand H) are extended toward the carry-in port 22 a of the load lock chamber 22. For this reason, the hand H is inserted into the entrance 22a.
Then, the work WK held by the hand H is moved to the target stop position W on the work table 22b in the load lock chamber 22.
3, the rotation drive of the turning shaft 12 and the second shaft 13 is stopped. Then, the vertical shaft 11 is driven downward. Therefore, the work WK can be placed at the target stop position W3 on the work table 22b.

FIG. 5 is a diagram showing the state at this time as viewed from the side.

The load lock chamber 22 is, as described above, a processing chamber 21 requiring high vacuum, high temperature, and high cleanliness.
It is integrated with. Therefore, in order to minimize contamination and temperature gradient due to contact with the outside air, the carry-in entrance 22a of the load lock chamber 22 may have a minimum size that allows the work WK and the hand H holding the work WK to pass therethrough. is necessary. That is, the vertical height of the carry-in entrance 22a needs to be minimum.

In order to minimize the vertical height of the loading port 22a, when the workpiece WK is loaded into the loading port 22a of the load lock chamber 22 by the workpiece transfer robot R1,
It is necessary to eliminate the bending ΔZ of the distal ends 14 of the arms 16 and 17 shown in FIG. 6 and to make the movement trajectory of the distal ends 14 of the arms 16 and 17 be a straight line along the horizontal direction.

In this embodiment, the following control is performed. Hereinafter, each case of the CP control and the PTP control will be described.

FIG. 8 is a control block diagram for performing the CP control. Hereinafter, the contents of the control processing performed in FIG. 8 will be described with reference to FIG. FIGS. 12A, 12B and 12C are top views showing the movement of the arms 16 and 17, and FIGS.
(D), (e), (f) is a side view showing the movement of the arm tip 14 (bending of the arm tip 14). In this embodiment, the arm tip 14 is located at the current position (command start position) P1.
Will be described by taking as an example a case where the robot moves from the target position to the target position P2.

As shown in FIG. 8, the target position setting section 31
Then, the target position P2 of the arm tip 14 is set. For example, the target position P2 of the arm tip 14 is obtained and stored by teaching. The current position setting section 32 detects the current position (command start position) P1 of the arm tip 14. For example, the current position P1 of the arm tip 14 is detected based on the detection values of the rotation angle sensors provided on the respective drive shafts 11, 12, and 13 (see FIG. 12A).

The bending amount calculating section 33 calculates the arm extension amount X
, The amount of deflection ΔZ of the arm tip 14 is calculated.

That is, the bending of the arms 16 and 17 is determined by the moments of inertia of the arms 16 and 17 and the work WK with respect to the base end of the arm (the pivot 12). Therefore, if the weights of the arms 16 and 17 and the work WK are determined, the bending amount ΔZ of the arm tip 14 is uniquely determined by the arm extension X of the work transfer robot R1. Therefore, the arm tip bending amount ΔZ can be expressed as a function of the arm extension amount X.

FIG. 11 shows the relationship between the arm extension X and the vertical movement Z. HL in FIG. 11 corresponds to the horizontal line, and the vertical movement amount Z of the horizontal line HL is defined as the origin 0. A curve L6 in FIG. 11 shows the measured value of the arm tip bending amount ΔZ with respect to the arm extension amount X. Curve L4
Is a curve obtained by inverting the curve L6 in the positive and negative directions, and shows the deflection correction amount ΔZ with respect to the arm extension amount X.

The correspondence L6 between the arm extension amount X and the arm tip bending amount ΔZ is stored in a storage table. Note that L4 may be stored.

In the present embodiment, the correspondence L6 between the arm extension amount X and the arm tip deflection amount ΔZ is stored in the storage table. However, the function f is determined as a predetermined function from the arm extension amount X to the arm tip deflection amount ΔZ. Expression ΔZ for calculating
= F (X) may be stored.

In the deflection amount calculating section 33, the command start position P1
Is calculated (read out) from the set storage content L6 of the above storage table. Similarly, arm tip flexure Δ corresponding to arm extension X2 at target position P2
Z2 is calculated from the setting storage content L6 of the storage table (see FIGS. 12A and 12D).

The trajectory planning section 34 calculates a desired trajectory L12 from the command start position P1 to the target position P2. The desired trajectory L12 is a straight line along the X axis (see FIG. 12B).

Then, via points P11 and P12 are set on the route L12 connecting P1 and P2, and the route L12 is divided into small sections (FIGS. 12B and 12E).

In the inverse converter 36, the sampling time Ta
Is generated and drive commands Z ', J1, J2 for the drive shafts 11, 12, 13 are generated and output.

That is, each time the sampling time Ta elapses via the sampler 35, each command position Ps on the locus L12
1, Ps2, P11, Ps3, Ps4, P12, Ps5, Ps6, and P2 are input to the inverse converter 36. That is, the distance between the command start position P1 and the passing point P11 is interpolated by the points Ps1 and Ps2, the distance between the passing point P11 and the passing point P12 is interpolated by the points Ps3 and Ps4, and the distance between the passing point P12 and the target point P2. Are interpolated by the points Ps5 and Ps6.

Each command position P for each sampling time
s1, Ps2, P11, Ps3, Ps4, P12, Ps5, Ps6, P2
12 is obtained (FIG. 12).
(F)).

For example, if the command position at a certain sampling time is P12 as shown in FIG. 11, the arm extension X12 corresponding to the command position P12 is obtained.
Arm tip flexure Δ corresponding to this arm extension X12
Z12 is determined from the correspondence L6. A deflection correction amount ΔZ12 corresponding to the arm extension amount X12 is obtained by reversing the above-obtained arm tip deflection amount ΔZ12. That is, the deflection correction amount Δ corresponding to the arm extension amount X12
Z12 is obtained from the curve L4 in FIG.

The deflection correction amount ΔZ1 at the command start position P1 is similarly obtained (see FIG. 11).

Next, the current command position P12 is set to the vertical axis 11
Is converted to a drive command Z ′ for the drive signal. That is, the difference ΔZ12 between the deflection correction amount ΔZ12 at the current command position P12 and the deflection correction amount ΔZ1 at the command start position P1.
-ΔZ1 is determined.

The drive command Z is corrected by adding the deviation ΔZ12−ΔZ1 to the original drive command Z (= 0) at the command position P12, and the corrected drive command Z ′ is applied to the vertical shaft 11. Is output.

The case where the current command position is P12 has been described as an example, but the deflection correction amount Zn corresponding to the command position Pn is similarly obtained at the other command positions Pn, and the original correction value at the current command position Pn is obtained. The drive command Z is corrected by adding the deviation ΔZn−ΔZ1 to the drive command Z (= 0), and the corrected drive command Z ′ is output to the vertical shaft 11.

On the other hand, the current command position P12 is
A process of converting the drive commands into the drive commands J1 and J2 for the second axis 13 is executed. That is, the arm extension amount X12 corresponding to the current command position P12 is obtained, and this arm extension amount X12 is obtained.
The respective axis drive commands J12 and J212 from which 12 are obtained are obtained by inverse conversion.

Then, the drive command J1 at the command position P12
12 is output to the turning shaft 12 and the drive command J
212 is output to the second shaft 13.

Although the case where the current command position is P12 has been described as an example, the arm extension amount Xn corresponding to the current command position Pn is similarly obtained when the other command position is Pn.
Each axis drive command J1n for obtaining the arm extension Xn,
J2n is obtained by the inverse conversion, the drive command J1n is output to the turning shaft 12, and the drive command J2n is
Output to axis 13.

In the control section 38, each drive shaft 11, 12, 1
The drive control of No. 3 is executed each time the sampling time Tb elapses. Note that T is between the sampling times Ta and Tb.
It is assumed that the relationship a ≧ Tb holds.

That is, each time the sampling time Tb elapses via the sampler 37, each command position Ps1, Ps2, P1
Drive commands at 1, Ps3, Ps4, P12, Ps5, Ps6, and P2 are input to the control unit 38.

Assuming that the current command position is P12, the drive command Z '(= Z + (ΔZ) corresponding to this command position P12
12-ΔZ1)), and the position and speed of the motor M1 for the vertical shaft 11 are controlled according to the drive command Z '. As a result, the vertical axis 11 is moved vertically Z ′ (= Z +
(ΔZ12−ΔZ1)).

The case where the current command position is P12 has been described as an example, but the drive command Z '(= Z + (ΔZn−) corresponding to the current command position Pn is similarly applied to other command positions Pn.
ΔZ1)) is input, and the position and speed of the motor M1 for the vertical shaft 11 are controlled according to the drive command Z '. As a result, the vertical axis 11 is moved vertically Z ′ (= Z + (ΔZn−Δ
Z1)).

Next, control of the turning shaft 12 and the second shaft 13 will be described.

Assuming that the current command position is P12, drive commands J112 and J212 corresponding to the command position P12 have been input. In response to the drive commands J112 and J212, the motor M2 for the turning shaft 12 The position and speed of the motor M3 for the two shafts 13 are respectively controlled. As a result, the pivot 12
Is driven by an angle J112 and the second shaft 13 is driven by an angle J212.

Although the description has been given taking the case where the current command position is P12 as an example, the drive commands J1n and J2n corresponding to the current command position Pn are similarly inputted when the other command position Pn is present. , J2n, the position and speed of the motor M2 for the turning shaft 12 and the motor M3 for the second shaft 13 are respectively controlled. As a result, the turning shaft 12 becomes the angle J1n.
And the second shaft 13 is driven by the angle J2n.

As described above, the arm tip 14 moves on the straight path L12 along the X axis from the command start position P1 to the target position P2. During this time, at each sampling time tn, the vertical drive amount is set so that the distal end 14 of the arms 16 and 17 moves vertically in the vertical direction Z opposite to the bending direction by the difference ΔZn−ΔZ1 with respect to the bending amount at the command start position. Z is corrected. As described above, according to the present embodiment, since the vertical drive amount Z is corrected, the arm tip 14 moves linearly along the horizontal line HL. That is, it is possible to prevent the movement locus of the work WK from becoming a curve shifted in the direction of its own weight.

PTP Control FIG. 9 is a control block diagram for performing PTP control.
Hereinafter, the contents of the control processing performed in FIG. 9 will be described with reference to FIG. FIG. 13A shows the arms 16 and 17.
13 (b) and 13 (c) are side views showing the movement of the arm tip 14 (bending of the arm tip 14). In the present embodiment, a case where the arm tip 14 moves from the current position (command start position) P1 to the target position P2 will be described as an example.

As shown in FIG. 9, the target position setting section 31
Then, the target position P2 of the arm tip 14 is set. For example, the target position P2 of the arm tip 14 is obtained and stored by teaching. The current position setting section 32 detects the current position (command start position) P1 of the arm tip 14. For example, the current position P1 of the arm tip 14 is detected based on the detection values of the rotation angle sensors provided on the drive shafts 11, 12, and 13 (see FIG. 13A).

The bending amount calculator 39 calculates the bending amount ΔZ of the arm tip 14 with respect to the rotation angle J2 of the second arm 17.

FIG. 10 shows the relationship between the rotation angle J2 of the second arm 17 and the vertical movement amount Z. HL of FIG.
Corresponds to the horizontal line, and the vertical movement amount Z of the horizontal line HL is defined as the origin 0. A curve L3 in FIG. 10 indicates an actually measured value of the arm tip bending amount ΔZ with respect to the second arm rotation angle J2.

As described above, when the PTP control is applied to the work transfer robot R1 of the embodiment, the rotation angle J2 of the second arm 17 (the drive amount J2 of the second shaft 13)
And the driving amount ΔZ of the vertical shaft 11 has the following relationship.

ΔZ = K · (1 + J2 / 180) (2) When this is generalized and expressed, the following equation is obtained.

ΔZ = a · J2 + b (3) where a and b are constants.

Therefore, the above equation (3) is stored as an approximate equation indicating the relationship between the rotation angle J2 of the second arm 17 and the deflection correction amount ΔZ.

The correspondence obtained from the above approximate expression (3) is shown as L1 in FIG.

In FIG. 10, the curve L1 obtained from the approximation equation (3) is approximately equal to the curve L6 indicating the actual measured amount of deflection obtained by inverting the sign.

In this embodiment, the approximate expression (3) is stored, but the correspondence L1 between the second arm rotation angle J2 and the deflection correction amount ΔZ obtained from the approximate expression (3) is stored in the storage table. You may let it.

In the deflection amount calculating section 39, the command start position P1
The deflection correction amount ΔZ1 corresponding to the second arm rotation angle J21 in is calculated from the approximate expression (3). Similarly, the deflection correction amount ΔZ2 corresponding to the second arm rotation angle J22 at the target position P2 is calculated from the above-described approximate expression (3) (see FIGS. 13A and 13B).

In the target position correcting section 40, the vertical drive command Z for the vertical axis 11 at the target position P2 is corrected.

That is, the difference ΔZ2−ΔZ1 between the deflection correction amount ΔZ2 at the target position P2 and the deflection correction amount ΔZ1 at the command start position P1 is obtained. The deviation ΔZ2 with respect to the original drive command Z (= 0) at the target position P2
The drive command Z is corrected by adding −ΔZ1 (see FIG. 13C). FIG. 13 (f) shows the correction drive command Z ', that is, the speed command for the motor M1 of the vertical shaft 11.

The horizontal drive command J at the target position P2
1, J2 is not corrected. FIG. 13D shows a drive command J1 for the turning shaft 12, that is, a speed command for the motor M2 of the turning shaft 12. FIG. 13E shows a drive command J2 for the second shaft 13, that is, the motor M of the second shaft 13.
3 shows a speed command.

In the case of PTP control, FIG.
As shown in (e) and (f), the acceleration / deceleration pattern of the speed command from the command start position P1 to the target position P2 is the same for each of the drive shafts 11, 12, and 13, and the operation time is The drive shafts 11, 12 and 13 coincide. That is, the time ta in the acceleration section of each speed command is equal, the time te in the constant velocity section is equal, and the time td in the deceleration section is equal.

The interpolation unit 41 generates and outputs speed commands Z ', J1, J2 for the drive shafts 11, 12, 13 each time the sampling time Ta elapses.

That is, every time the sampling time Ta elapses via the sampler 35, the current speed command is output to the motor M1 for the vertical shaft 11 according to the speed command pattern Z 'shown in FIG. Similarly, every time the sampling time Ta elapses, the current speed command is output to the motor M2 for the turning shaft 12 according to the speed command pattern J1 shown in FIG. 13D, and the speed command shown in FIG. The current speed command is output to the motor M3 for the second shaft 13 according to the pattern J2. In this way, the interpolation between the command start position P1 and the target position P2 is performed.

In the control unit 42, each drive shaft 11, 12, 1
The drive control of No. 3 is executed each time the sampling time Tb elapses. Note that T is between the sampling times Ta and Tb.
It is assumed that the relationship a ≧ Tb holds.

That is, a speed command is input to the control unit 42 via the sampler 37 every time the sampling time Tb elapses. Each motor M is set so that this speed command is obtained.
1, M2 and M3 are drive-controlled.

As described above, the arm tip 14 moves along the X axis from the command start position P1 to the target position P2. During this time, at each sampling time tn, the tip 14 of the arms 16 and 17 moves in the vertical direction Z opposite to the bending direction in the deflection correction amount difference ΔZn−Δ based on the approximate expression (3).
The vertical drive amount Z is corrected so as to move vertically by Z1. L2 in FIG. 10 indicates a measured value of the amount of deflection after correction. As can be seen from FIG. 10, according to the present embodiment, the vertical drive amount Z is calculated based on the approximate expression (3).
, The arm tip 14 moves linearly along the horizontal line HL. That is, the work WK
Is prevented from becoming a curve shifted in the direction of its own weight.

The effect of correcting the vertical drive amount Z according to the above equation (3) will be described with reference to FIG.

FIG. 14A shows a case where an approximate deflection correction amount ΔZ is obtained based on the above equation (3), and FIG.
Shows a case where the approximate deflection correction amount ΔZ is obtained based on an equation different from the equation (3).

Depending on the operating mode of the work transfer robot R1, in addition to the operating mode in which the arm tip 14 is moved from the command start position P1 to the target position P2, the arm tip 14 is moved from the command start position P1 to the intermediate position just before the target position P2. There is an operation mode of moving to P3 and temporarily stopping at this intermediate position P3.

In the case of the control of this embodiment shown in FIG. 14A, the deflection correction amount ΔZ2 at the target point P2 is obtained according to the above equation (3), and the deflection correction amount ΔZ3 at the intermediate point P3 is obtained. Then, the drive amount ΔZ of the vertical shaft 11 changes according to the same equation (3). Therefore, the target point P2
The deflection correction amount ΔZ3 when passing through the intermediate point P3 when the arm tip 14 is moved to
The deflection correction amount ΔZ3 at the intermediate point P3 when the shutter 4 is stopped coincides. That is, there is no error between the height of the arm tip 14 when passing through the intermediate point P3 up to the target point P2 and the height of the arm tip 14 when the arm tip 14 is once stopped at the intermediate point P3.

On the other hand, in the case of FIG. 14B, the deflection correction amount ΔZ2 ′ at the target point P2 is obtained according to an equation different from the above equation (3), and the deflection correction amount ΔZ3 ′ at the intermediate point P3 is obtained. Desired. Then, the driving amount ΔZ of the vertical shaft 11 changes according to the above equation (3). Therefore, the intermediate point P3 when the arm tip 14 is moved to the target point P2
The deflection correction amount ΔZ3 at the time of passing (this is obtained based on the equation (3)) and the deflection correction amount ΔZ3 ′ at the intermediate point P3 when the arm tip 14 is stopped once at the intermediate point P3.
(This is obtained from an equation different from equation (3)). That is, an error occurs between the height of the arm tip 14 when passing through the intermediate point P3 up to the target point P2 and the height of the arm tip 14 when the arm tip 14 is temporarily stopped at the intermediate point P3.

As described above, according to the present embodiment, the height of the arm tip 14 when passing through the intermediate point P3 in the middle of the target point P2 and the arm tip 14 when temporarily stopped at the intermediate point P3
And the height can be matched.

In this embodiment, the description has been made on the assumption that the weight of the turning arm 16, the second arm 17, and the weight of the work WK of the work transfer robot R1 are univocal. However, the present invention can cope with a case where the type of the work transfer robot and the type of the work WK are different and the weight of the revolving arm 16 and the second arm 17 and the weight of the work WK change.

In the case of the CP control, the amount of arm bending or the amount of bending correction ΔZ may be stored in accordance with the weight of the turning arm 16, the second arm 17, and the weight of the work WK.

In the case of PTP control, the swing arm 1
6. The constants a and b in the approximate expression (3) may be determined according to the weight of the second arm 17 and the weight of the work WK.

[Brief description of the drawings]

FIG. 1 is a side view illustrating a configuration of a work transfer robot according to an embodiment.

FIG. 2 is a top view illustrating a configuration of a work transfer robot according to the embodiment.

FIG. 3 is a top view illustrating the manufacturing system according to the embodiment.

FIGS. 4A and 4B are top views showing a state where a work is carried in by a work transfer robot.

FIG. 5 is a side view showing a state where a work is carried in by a work transfer robot.

FIG. 6 is a side view for explaining how the arm bends.

FIG. 7 is a top view illustrating a geometric relationship of an arm of the work transfer robot according to the embodiment.

FIG. 8 is a control block diagram of the embodiment.

FIG. 9 is another control block diagram of the embodiment.

FIG. 10 is a graph showing a relationship between a second arm angle and a vertical movement amount.

FIG. 11 is a graph showing the relationship between the amount of arm extension and the amount of vertical movement.

12 (a) to 12 (f) are diagrams for explaining control processing corresponding to FIG.

13 (a) to 13 (f) are diagrams for explaining control processing corresponding to FIG.

FIGS. 14A and 14B are diagrams showing a relationship between an arm tip and a deflection correction amount.

[Explanation of symbols]

 R2 Work transfer robot WK Work 11 Vertical axis 12 Swivel axis 13 Second axis 16 Swivel arm 17 Second arm

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasuo Samejima 400 Yokokura Nitta, Oyama City, Tochigi Prefecture Komatsu Plant Koyama Plant F-term (reference) 2H088 FA17 FA30 MA20 3F059 AA01 AA14 AA16 BA04 BA08 DA08 FB17 3F060 AA01 AA07 AA08 BA00 DA09 DA10 EB12 EC12 FA01 5F031 CA02 CA05 FA11 FA12 GA42 GA43 GA49 MA09 MA28 MA29

Claims (4)

[Claims] An arm that is cantilevered with respect to a base end, a horizontal drive shaft that horizontally moves the arm tip with respect to the base end by a horizontal movement amount according to a drive command;
A vertical drive axis for vertically moving the arm by a vertical movement amount according to the drive command, and controlling the transfer of the work at the tip of the arm by generating the drive command and outputting it to the horizontal drive axis and the vertical drive axis. A control unit for the work transfer device, comprising: a bending amount setting unit configured to set a vertical bending amount of the arm in association with a horizontal movement amount of the arm tip, wherein the control unit includes: A bending amount corresponding to the current horizontal movement amount of the tip of the arm is obtained from the setting contents of the bending amount setting means, and the vertical movement is performed so that the arm vertically moves in the vertical direction opposite to the bending direction by the bending amount. A control device for a work transfer device for correcting the amount and outputting the drive command. 2. The control unit outputs the drive command at each sampling time so that the tip of the arm draws a desired trajectory from a command start position to a target position. The amount of bending corresponding to the amount of horizontal movement of the tip of the arm is determined from the setting of the amount of bending setting means, and the amount of vertical movement is set so that the arm vertically moves by the amount of bending in the vertical direction opposite to the direction of bending. 2. The control device for a work transfer device according to claim 1, wherein the drive command at the current sampling time is corrected and output. 3. The control means outputs the drive command such that the tip of the arm sequentially reaches each target position, and the bending amount setting means sets a distance between the target positions of the arm. Setting the relationship of the drive amount of the vertical drive shaft to the drive amount of the horizontal drive shaft when moving as the relationship of the amount of vertical deflection of the arm to the amount of horizontal movement of the tip of the arm; The means obtains a bending amount corresponding to the horizontal movement amount of the arm tip at the next target position from the setting contents of the bending amount setting means, and the arm vertically moves by the bending amount in a vertical direction opposite to the bending direction. The control device for a work transfer device according to claim 1, wherein the drive command is output after correcting the vertical movement amount so as to perform the driving command. 4. The control device for a work transfer device according to claim 1, wherein the bending amount setting means sets a bending amount in accordance with a type of the arm or a type of the work.