JP2007018439A - Gantry type XY positioning device - Google Patents

Abstract

A gantry type XY positioning device capable of performing optimum positioning control in various movement patterns is provided.
By controlling the position of the X-axis frame 16 on the Y-axis frames 14A and 14B and the position of the moving object 18 on the X-axis, the moving object 18 can be moved and positioned in the XY plane. In the gantry-type XY positioning device GP3, the object to be moved on the X-axis frame 16 is included in the control system of the Y-axis motors 20A and 20B for controlling the position of the X-axis frame 16 on the Y-axis frames 14A and 14B. Observer calculation units 80A and 80B for estimating the amount of disturbance torque received by the Y-axis motors 20A and 20B due to the movement of the Y-axis 18 and the like, and based on the estimated value Te in the observer calculation units 80A and 80B, The drive command value Itp (It) of the motors 20A and 20B is corrected.
[Selection] Figure 1

Description

  The present invention relates to a gantry type XY positioning device used in an electronic component mounting apparatus or the like.

  An XY positioning device for moving and positioning a transfer head for mounting an electronic component on a substrate and a tool for performing cutting or the like to a predetermined position on an XY plane is widely used. As an example of this type of XY positioning device, a gantry-type (gate-type) XY positioning device is disclosed in, for example, Patent Document 1.

  This gantry type XY positioning device GP1 includes a pair of Y-axis frames 14A and 14B and an X-axis frame 16 arranged in parallel as shown in FIG. The X-axis frame 16 is constructed with both end portions 16A and 16B straddling the Y-axis frames 14A and 14B. The X-axis frame 16 incorporates a transfer head 18 that is a movement target so as to be slidable. By controlling the position of the X-axis frame 16 on the Y-axis frames 14A and 14B and the position of the transfer head 18 on the X-axis frame 16, the transfer head 18 can be moved and positioned in the XY plane. It is like that.

  The positioning device GP1 includes a pair of Y-axis motors 20A and 20B, and controls the positions of the X-axis frame 16 on the Y-axis frames 14A and 14B via the Y-axis motors 20A and 20B. The positioning device GP1 includes an X-axis motor 22 at the end of the X-axis frame 16, and controls the position of the transfer head (moving target) 18 on the X-axis frame 16 via the X-axis motor 22. ing.

  In the example of FIG. 5, for driving the transfer head 18, both the X-axis direction and the Y-axis direction are provided with a rotary X-axis motor 22 and Y-axis motors 20 </ b> A, 20 </ b> B. The timing belts 26A to 26E are combined, but a ball screw may be used instead of the timing belts 26A to 26E, or a linear motor may be used instead of the rotary motor.

  Both end portions 16A and 16B of the X-axis frame 16 must be driven synchronously on the Y-axis frames 14A and 14B. In this specific control, precise control is performed by focusing on only one of the all-axis control methods in which the Y-axis motors 20A and 20B are independently controlled in each of the pair of Y-axis frames 14A and 14B. There is a master / slave type control method in which the other is subordinated to this.

  However, when positioning is performed by the positioning device GP1, the balance of the loads received by both the Y-axis frames 14A and 14B slightly changes, so that a deviation occurs in the movement of both the Y-axis motors 20A and 20B, and positioning accuracy and There was a problem of adversely affecting the positioning time.

  As a technique for preventing this, the technique described in Patent Document 2 is known.

  This technique will be briefly described with reference to FIG. 6. In the gantry-type XY positioning device GP2 according to Patent Document 2, when the command pulse generated by the command pulse generator 51 is input to the deviation counters 52 and 53, The Y-axis motors 57 and 58 are operated, and the deviations A and B are stored in the deviation counters 52 and 53, respectively. If the deviations A and B are equal, the deviation between the pair of Y axes becomes zero, but if the deviations A and B have different values, the position deviation compensator 56 integrates the difference between the deviations A and B, Different compensation values K1, K2 are calculated and added to the deviations A, B to obtain speed commands R1, R2. The speed commands R1 and R2 are amplified by the speed amplifiers 54 and 55. When the motors 57 and 58 are driven by the speed commands R1 and R2, the position deviation between the left and right Y-axis frames 59 and 60 is integrated and compensated. Control that can eliminate the positional deviation between the axes can be performed.

  Here, the speed amplifiers 54 and 55 are variable gain amplifiers, and their gains are adjusted according to the position on the X-axis frame 62 of the moving object 63 detected by the position detector 64. As a result, the substantial speed loop gain is prevented from changing due to the position of the moving object 63 on the X-axis frame 62.

Japanese Patent Application No. 2003-140751 Japanese Patent No. 3125015

  However, in the technique proposed in Patent Document 2, as shown in FIG. 7, the “position” of the movement target (load) on the X axis is simply detected, and the static inertia value applied to both Y axes is detected. Since the speed loop gain of each axis is changed on the basis of the above, there is a problem that it is not possible to cope with the case where the moving object is accelerated or decelerated on the X axis.

  In actual positioning, if the target coordinates are shifted from the current coordinates with the X and Y axes, the moving object is naturally driven in the Y axis direction while moving on the X axis. The movement speed depends on the deviation. If the movement speed is largely deviated, the movement speed increases accordingly. If the acceleration / deceleration is different, the influence of each Y-axis motor is also different.

  For this reason, simply changing the speed loop gain simply depending on the “position on the X-axis” of the movement target makes it difficult to always optimally compensate for various movement patterns. Met.

  The present invention has been made to solve such a conventional problem, and it is possible to perform optimum positioning control in various movement patterns by comprehensively considering the static and dynamic influences of the movement target. An object of the present invention is to provide a gantry-type XY positioning device that can be used.

  The present invention includes a pair of Y-axis frames arranged in parallel and an X-axis frame having both end portions straddling the Y-axis frame, the position of the X-axis frame on the Y-axis frame, and In a gantry-type XY positioning device that can move and position the moving object in the XY plane by controlling the position of the moving object on the X-axis, the position of the X-axis frame on the Y-axis frame is determined. In the control system of the Y-axis motor for controlling, an observer calculation unit that estimates an amount equivalent to the disturbance torque received by the Y-axis motor due to the movement of the moving object on the X-axis frame, The problem is solved by correcting the drive command value of the Y-axis motor based on the estimated value in the observer calculation unit.

  In the present invention, attention has been paid to the fact that the extent of the influence of the X-axis direction position of the movement target and acceleration / deceleration on each Y-axis motor can be grasped as a result of the disturbance torque applied to each Y-axis motor. Based on this knowledge, in the present invention, an observer calculation unit is provided in the control system of the Y-axis motor to estimate the amount corresponding to this disturbance torque received by the Y-axis motor, and based on this estimated value, a drive command value for the Y-axis motor I am trying to correct. Therefore, optimum positioning control can always be performed even when the moving object is positioned at any position on the X axis while performing any acceleration / deceleration.

  In the present invention, there is no particular limitation on how to correct the drive command value of the Y-axis motor based on the estimated value corresponding to the disturbance torque. When the control system includes a speed control unit that generates the speed command value of the Y-axis motor, the speed command gain in the speed control unit is made variable based on the estimated value corresponding to the disturbance torque. The correction may be performed.

  In the present invention, the correction may be performed by adding an estimated value corresponding to the disturbance torque at a predetermined addition point of the control system of the Y-axis motor. In this case, it is better to use a correction for varying the speed command gain in the speed control unit based on the estimated value corresponding to the torque disturbance.

  In the present invention, basically, the all-axis control method for independently controlling the Y-axis motor in each of the pair of Y-axis frames is also allowed to perform precise control by paying attention to only one of the control methods. The present invention can also be applied to a master / slave type control system in which the other is subordinate to this. However, according to the present invention, when this is applied to an all-axis control method and the correction is performed independently in each Y-axis motor in the pair of Y-axis frames, a more remarkable effect can be obtained. It is done.

  According to the present invention, it is possible to always perform optimum positioning in various movement patterns in consideration of the static and dynamic effects of the movement target.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 1, in the present embodiment, the present invention is applied to a gantry-type XY positioning device GP3 according to the electronic component mounting apparatus described above. However, in this embodiment, the rotational outputs of the Y-axis motors 20A and 20B are transmitted to both ends 16A and 16B of the X-axis frame 16 via the ball screws 30A and 30B (not via the timing belt). Yes.

  That is, as shown in the right part of FIG. 1, this gantry-type XY positioning device GP3 also includes a pair of Y-axis frame 14 and X-axis frame 16 arranged in parallel. For convenience of explanation, each Y-axis system is denoted by adding A at the end of the reference to the upper Y-axis system of FIG. 1 and B at the end of the reference for the lower Y-axis system. A distinction will be made as appropriate. The X-axis frame 16 is constructed with both end portions 16A and 16B straddling the Y-axis frames 14A and 14B. A transfer head 18 to be moved is slidably incorporated in the X-axis frame 16. It is.

  The positioning device GP3 includes a pair of Y-axis motors 20A and 20B, and controls the positions of the X-axis frame 16 on the Y-axis frames 14A and 14B via the Y-axis motors 20A and 20B. Further, the positioning device GP3 includes an X-axis motor 22 at the end of the X-axis frame 16, and controls the position of the transfer head (moving target) 18 on the X-axis frame 16 via the X-axis motor 22. ing. Thereby, the transfer head 18 can be freely moved and positioned in the XY plane. This is the same as the conventional example already described.

  However, as shown in the left part of FIG. 1, the control system C of the Y-axis motors 20A and 20B in this embodiment performs the following positioning control in various movement patterns of the transfer head 18. It is set as such.

  That is, the control system C includes a position command unit 70, position control units 72A and 72B, variable gain speed control units 74A and 74B, servo amplifier units 76A and 76B, speed detection units 78A and 78B, and an observer unit. 80A and 80B are provided.

  The position command unit 70 commands a target position Pt for driving and positioning the transfer head 18. The position controllers 72A and 72B generate a target speed command value Vt based on the position deviation Dp between the target position Pt calculated at the addition points 82A and 82B and the actual detection position Pd. The speed controllers 74A and 74B are fed back from the target speed command value Vt calculated at the addition points 84A and 84B and the encoders 32A and 32B (calculated by the speed detectors 78A and 78B based on the encoder signal Pd). The target current command value It is calculated based on the speed deviation Dv from the actual speed ω. In calculating the target current command value It from the speed deviation Dv, the gain Gv is changed in a timely manner (described later). The servo amplifiers 76A and 76B amplify the target current command value It to a magnitude Itp that can drive the Y-axis motors 20A and 20B. The speed detectors 78A and 78B calculate the actual speed ω of the Y-axis motors 20A and 20B from the time change of the actual detection position Pd of the encoders 32A and 32B.

  Here, the configuration of the observer units 80A and 80B will be described in detail.

  The observer units 80A and 80B estimate the amount corresponding to the disturbance torque received by the Y-axis motors 20A and 20B due to the movement of the transfer head (movement target) 18 on the X-axis frame 16. FIG. 2 shows the configuration of the A series (80A).

  In the observer unit 80A according to the present embodiment, the target current command value It and the actual feedback speed ω of the Y-axis motor 20A are used as input elements, while the torque constant nominal value Ktn and the motor inertia nominal value Jmn are reversed. The estimated value Te corresponding to the disturbance torque is obtained by calculation. In the transfer function in the block of FIG. 2, symbol s indicates a Laplace operator, and g indicates an observer gain (low-pass gain). The block 86A functions as a low-pass filter.

  Since the block diagram shown in FIG. 2 includes differential elements, actually, an estimation calculation of the estimated value Te corresponding to the disturbance torque is performed using the block diagram as shown in FIG. 3 which is equivalent to this. . The B series also includes an observer unit 80B that is exactly the same as the A series observer unit 80A.

  Returning to FIG. 1, the estimated value Te corresponding to the disturbance torque calculated by the observer units 80A and 80B is input to the speed control units 74A and 74B, and is used to adjust / change the speed loop gain (speed command gain) Gv. Is done. When the estimated value Te increases, the speed loop gain Gv is set high. On the other hand, when the estimated value Te decreases, the speed loop gain Gv is set low. When actually adjusting the gain, a correspondence between the estimated value Te and the gain Gv obtained experimentally in advance is prepared as a Te-Gv table, and the gain Gv is set according to the estimated value Te. It is practical to switch.

  Next, the operation of the gantry-type XY positioning device GP3 according to this embodiment will be described focusing on the A series for convenience.

  When the position deviation Dp between the target position Pt from the position command unit 70 and the actual detection position Pd from the encoder 32A is calculated at the addition point 82A, the target speed command value Vt is obtained at the position control unit 72A. This target speed command value Vt is compared with the actual speed ω of the Y-axis motor 20A fed back via the encoder 32A and the speed detector 78A at the addition point 84A, and the deviation Dv is input to the speed controller 74A. The As a result, the target current command value It is generated in a form in which proportional control and integral control are used together. Since the torque of the Y-axis motor 20A increases or decreases depending on the magnitude of the current value, the target current command value It corresponds to a target torque command for the Y-axis motor 20A. Thereafter, the target current command value It is amplified to the current value Itp by the servo amplifier 76A, and the Y-axis motor 20A is driven.

  Here, an estimated value Te corresponding to the disturbance torque estimated to be actually generated in the motor 20A is obtained in the observer unit 80A, and this information is transmitted as a gain switching signal to the speed control unit 74A.

  In the speed control units 74A and 74B, when the estimated value Te increases according to the value of the estimated value Te (when it is estimated that the disturbance torque has increased), the speed loop gain Gv is calculated from the Te-Gv table. A higher target speed command value Vt is generated by setting it higher, and the generated torque of the Y-axis motor 20A is increased.

  On the other hand, when the estimated value Te decreases (when it is estimated that the disturbance torque has decreased), the speed loop gain Gv is set low to generate a lower target speed command value Vt, and the Y-axis motor Reduce the generated torque of 20A.

  In this embodiment, since the speed loop gain Gv is adjusted / changed based on the estimated value Te, it is possible to make a simple correction with good responsiveness.

  Exactly the same operation is performed for the B-series Y-axis motor 20B.

  As a result, control that effectively cancels the influence of disturbance torque on the Y-axis motors 20A and 20B due to the position of the transfer head 18 on the X-axis frame 16 and acceleration / deceleration during movement is performed. Thus, optimum positioning control is possible.

  In the above embodiment, the control by the encoder at the Y-axis motor end has been described as an example, but it is naturally possible to apply the control in the fully closed control using the linear encoder.

  Further, in the above embodiment, an example in which the estimated value corresponding to the disturbance torque calculated in the observer unit is used for gain adjustment in the speed control unit has been shown. In particular, it is not limited to this example as to how it is reflected in the correction of the drive command value of the Y-axis motor. In short, the final drive command value of the Y-axis motor (as described above) In the case of the configuration, it is only necessary to adjust / change Itp). For example, by using this estimated value, the proportional gain in the position control units 72A and 72B may be changed, or the gain of current amplification in the servo amplifier units 76A and 76B may be changed.

  Further, for example, as shown in FIG. 4, in the case of a gantry type XY positioning device GP4 capable of sufficiently increasing the observer gain (low-pass gain) g, this estimated value is set to any addition point. (In the example shown in the figure, a configuration may be adopted in which addition points 90A and 90B) are added as control signals. In this case, the estimated value can be reflected more finely in the control of the Y-axis motors 20A and 20B.

  As exemplified in the above-described embodiment, the present invention is applied to an all-axis control method, and the correction by the estimated value is performed independently for each of the pair of Y-axis motors. In particular, a remarkable effect can be obtained. However, the application target of the present invention is not necessarily limited to only a positioning device that employs an all-axis control method, and allows precise control by focusing only on one Y-axis motor. Even if it is applied to a master / slave type control system that depends on the above, a corresponding effect can be obtained in that the control on the master side can cancel the increase / decrease in disturbance torque. In addition, the master / slave control method is rather superior in that there is no control interference of each axis, and therefore a sufficiently beneficial effect can be obtained depending on the application target.

  The present invention can be widely applied to a gantry-type XY positioning device for moving and positioning a transfer head for mounting electronic components on a substrate and a tool for performing cutting and the like to a predetermined position on an XY plane.

The block diagram which shows typically the whole structure of the gantry type XY positioning device which concerns on one Embodiment of this invention. Block diagram showing the configuration of the observer section of the equipment Block diagram equivalent to the observer part of FIG. 1 is a block diagram corresponding to FIG. 1 schematically showing the overall configuration of a gantry-type XY positioning device according to another embodiment of the present invention. The perspective view which shows the whole structure of the gantry type | mold XY positioning apparatus of patent document 1 Block diagram schematically showing the overall configuration of the gantry-type XY positioning device described in Patent Document 2 The graph which shows the inertia characteristic of the motor used in the apparatus of FIG.

Explanation of symbols

14A, 14B ... Y-axis frame 16 ... X-axis frame 16A, 16B ... Both ends 18 ... Transfer head (moving target)
20A, 20B ... Y-axis motor 22 ... X-axis motor 30A, 30B ... Ball screw 32A, 32B ... Encoder 70 ... Position command unit 72A, 72B ... Position control unit 74A, 74B ... Variable gain speed control unit 76A, 76B ... Servo amplifier Part 78A, 78B ... speed detection part 80A, 80B ... observer part

Claims (4)

A pair of Y-axis frames arranged in parallel and an X-axis frame having both ends extending over the Y-axis frame, the position of the X-axis frame on the Y-axis frame and the X of the movement target In the gantry-type XY positioning device that can move and position the moving object in the XY plane by controlling the position on the axis,
In the control system of the Y-axis motor for controlling the position of the X-axis frame on the Y-axis frame, the disturbance received by the Y-axis motor due to the movement of the moving object on the X-axis frame It has an observer calculator that estimates the torque equivalent,
A gantry-type XY positioning device that corrects a drive command value of the Y-axis motor based on an estimated value in the observer calculation unit.   The Y-axis motor control system includes a speed control unit that generates a speed command value for the Y-axis motor, and the speed command gain in the speed control unit is variable based on an estimated value corresponding to the disturbance torque. The gantry-type XY positioning device according to claim 1, wherein the correction is performed as described above.   The gantry-type XY positioning apparatus according to claim 1 or 2, wherein the correction is performed by adding an estimated value corresponding to the disturbance torque at a predetermined addition point of a control system of the Y-axis motor. .   The gantry-type XY positioning device according to claim 1, wherein the correction is performed independently in each Y-axis motor in the pair of Y-axis frames.

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