JP2004234205A - Numerical controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a numerical controller capable of precisely compensating elastic change generated when the moving direction of an object to be controlled is inversed. <P>SOLUTION: When the control direction of a table 6 is inversed, the correction command value of backlash is updated according to an elapsed time since the inversion is generated, and the correction command value is added to a position command value, and the rotation of a survo motor 1 for driving the table 6 is controlled based on the addition result. Thus, it is possible to precisely compensate elastic change generated when the moving direction of the table 6 is inversed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a numerical controller that controls the position of a control target such as a table.
[0002]
[Prior art]
For example, if a drive mechanism using a ball screw adopts a fully-closed control system in which a sensor such as a linear scale detects position information of a control target and feeds back the information, the machine end is used when the movement direction of the control target is reversed. Although it is possible to detect the lost motion (play or elastic deformation) caused by the sensor with a sensor, a quadrant projection may be generated due to a response delay of the feedback control system.
In order to suppress the occurrence of quadrant protrusions, a conventional numerical control device adds a trapezoidal or rectangular backlash correction amount of a predetermined width to a position command value of a control target when the movement direction of the control target is reversed. I have to. In addition, the width of the trapezoid is determined in advance by measuring the shape of a protrusion that occurs when no correction is made with a sensor (see Patent Document 1 below).
[0003]
[Patent Document 1]
JP-A-2000-35814 (Pages 5 to 9, FIG. 5)
[0004]
[Problems to be solved by the invention]
Since the conventional numerical control device is configured as described above, every time the control conditions such as the moving speed of the control target and the arc radius change, the projection shape generated when no correction is applied is measured by the sensor, and the trapezoidal shape is obtained. Needs to be determined. Therefore, when the control target is driven by a continuous operation in which various moving speeds and arc radii are combined, there is a problem that requires much labor.
In addition, the shape of the backlash correction amount is trapezoidal or rectangular and is added to the position command value of the control target. However, the shape of the error that actually occurs does not always become trapezoidal or rectangular, so the quadrant projections are accurately detected. There was a problem that generation could not be suppressed.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a numerical control device capable of accurately compensating for elastic deformation that occurs when a moving direction of a control target is reversed.
[0006]
[Means for Solving the Problems]
The numerical control device according to the present invention is provided with a correction command value updating means for updating a backlash correction command value in accordance with an elapsed time after the reversal of the control direction of the control object, The backlash correction command value updated by the command value updating means is added to the position command value, and the rotation of the motor driving the control target is controlled based on the addition result.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a numerical control device according to a first embodiment of the present invention. In the figure, a servo motor 1 drives a table 6 to be controlled in a left or right direction in the figure. Numeral 2 detects the rotation amount of the servo motor 1. The coupling 3 couples the servomotor 1 and the ball screw 4, and the ball screw nut 5 is fitted with the ball screw 4. A work piece, a tool, and the like are fixed to the table 6 to be controlled, and are connected to the ball screw nut 5.
[0008]
The linear scale 7 is fixed to a base portion (not shown) and detects the position of the table 6. The linear scale head 8 is fixed to the table 6 and fitted with the linear scale 7.
The ball screw 4 and the ball screw nut 5 convert the rotary motion of the servo motor 1 into a linear motion, and the table 6 includes a drive transmitting member such as the ball screw 4 and the ball screw nut 5, a linear motion guide mechanism (guide rail) not shown. Is moved to a predetermined position.
[0009]
When numerically controlling the position of the table 6 (the position in the predetermined uniaxial direction), the position command generator 9 generates a position command value according to, for example, a machining program. The control direction detector 10 monitors the position command value generated by the position command generator 9 to detect the control direction of the table 6 in the axial direction, and has a positive or negative magnitude “1” according to the control direction. Is output. However, if the control direction is not reversed, the same control direction signal as the previous one is output. In the initial state, a control value signal having a zero value is output. Note that the control direction detection unit 10 constitutes a control direction detection unit.
[0010]
The friction compensation gain unit 11 multiplies the control direction signal output from the control direction detection unit 10 by a predetermined friction compensation gain, and calculates a current command correction value corresponding to a correction torque amount for canceling friction acting on the table 6 based on the multiplication result. Is output to the adder 17.
The maximum backlash correction gain section 12 multiplies the control direction signal output from the control direction detection section 10 by a predetermined maximum backlash correction amount, and uses the multiplication result as a step-like maximum backlash correction signal as a transfer function filter 13. Output to The transfer function filter 13 models the transfer function from the friction acting on the table 6 to the deviation between the position of the table 6 and the position of the servo motor 1, and outputs the maximum value output from the maximum backlash correction gain unit 12. When a backlash correction signal is input, a backlash correction command value corresponding to the elapsed time after the inversion of the control direction of the table 6 is output. The maximum backlash correction gain unit 12 and the transfer function filter 13 constitute a correction command value updating unit.
[0011]
The adder 14 adds the position command value generated by the position command generator 9 and the correction command value updated by the transfer function filter 13, and the position controller 15 outputs the addition result of the adder 14 and the linear scale head 8. A speed command value is generated based on a difference from the output position information of the table 6.
The speed control unit 16 converts the rotation angle information of the servo motor 1 output from the encoder 2 into a position coordinate system to obtain speed information of the servo motor 1, and obtains the speed information and the speed command value generated by the position control unit 15. And generates a current command value based on the difference between The adder 17 adds the current command value generated by the speed control unit 16 and the current command correction value output from the friction compensation gain unit 11 to generate a corrected current command value (control signal). The current control unit 18 controls the rotation of the servo motor 1 based on the correction current command value generated by the adder 17. The control means includes the friction compensation gain unit 11, the adder 14, the position control unit 15, the speed control unit 16, the adder 17, and the current control unit 18.
[0012]
Next, the operation will be described.
First, when numerically controlling the position of the table 6 (the position in the predetermined uniaxial direction), the position command generator 9 generates a position command value according to, for example, a machining program.
When the position command generator 9 starts generating the position command value, the control direction detector 10 monitors the position command value and detects the control direction of the table 6 in the axial direction.
For example, when the table 6 is moving rightward in the drawing, a control direction signal of "+1" is output, and when the table 6 is moving leftward, a control direction signal of "-1" is output.
[0013]
When receiving the control direction signal of “+1” or “−1” from the control direction detection unit 10, the maximum backlash correction gain unit 12 multiplies the control direction signal by a predetermined maximum backlash correction amount, and calculates the multiplication result. Is output to the transfer function filter 13 as the maximum backlash correction signal.
Upon receiving the maximum backlash correction signal from the maximum backlash correction gain unit 12, the transfer function filter 13 uses the maximum backlash correction signal as an input condition and lapses from the time when the control direction of the table 6 is inverted. And outputs a backlash correction command value corresponding to.
[0014]
When the transfer function filter 13 updates the backlash correction command value, the adder 14 adds the correction command value and the position command value generated by the position command generation unit 9, and the position control unit 15 A speed command value is generated based on the difference between the addition result of No. 14 and the position information of the table 6 output from the linear scale head 8.
When receiving the control direction signal of "+1" or "-1" from the control direction detection unit 10, the friction compensation gain unit 11 multiplies the control direction signal by a predetermined friction compensation gain, and corrects the multiplication result by the current command correction. The value is output to the adder 17 as a value.
[0015]
The adder 17 adds the current command value generated by the speed control unit 16 and the current command correction value output from the friction compensation gain unit 11 to generate a corrected current command value.
When the adder 17 generates the corrected current command value, the current control unit 18 controls the rotation of the servo motor 1 based on the corrected current command value. That is, the drive current of the servo motor 1 is controlled.
Thus, the rotation shaft of the servo motor 1 rotates by an angle corresponding to the drive current of the servo motor 1, and the table 6 moves by a distance corresponding to the rotation.
[0016]
Here, FIG. 2 is an explanatory diagram for explaining elastic deformation occurring between the servo motor 1 and the table 6.
M represents the rotational motion of the servomotor 1 equivalently converted to the linear motion coordinate system of the table 6, L represents the table 6, and K represents the elastic elements included in the drive transmission member such as the ball screw 4. C is a representation of the damping elements included in the drive transmission member collectively in the coordinate system of the table 6.
[0017]
FIG. 2A shows a case where the servo motor M and the table L are moving to the right. That is, the driving force U acting on the servo motor M and the dynamic friction F acting on the table L are balanced, and the elastic element K is contracted.
FIG. 2B shows a case where the servo motor M and the table L are moving to the left. That is, the directions of the driving force U and the dynamic friction F are reversed, and the elastic element K is extended.
When the position command value for the table 6 is reversed from right to left, the position of the table 6 is detected by the linear scale 7 and the linear scale head 8, and feedback control is performed. Table 6 can be made to follow the position command value. However, since the feedback control system has a response delay, a tracking error occurs only with the feedback control.
[0018]
FIG. 3 is a block diagram showing a control system of the numerical controller according to the first embodiment. The table 6 and the servomotor 1 are dynamically modeled using an inertia moment and a spring interposed therebetween. JL is the moment of inertia of the table 6, JM is the moment of inertia of the servomotor 1, K is the spring constant representing the rigidity of the drive transmission member such as the ball screw 4, C is the coefficient of viscous friction acting on the spring, and s is the Laplace operation representing the derivative. I am a child.
F is a dynamic friction torque acting on the table 6, and F0 is a friction compensation torque for canceling the dynamic friction. V (s) is the speed control unit 16 and is expressed by, for example, Kv (1 + Ki / s), where Kv is a speed proportional gain and Ki is a speed integration gain. P (s) is a position control unit 15, which is represented by, for example, a position proportional gain Kp. θr is the position command value, θM is the position of the servo motor 1, and θL is the position of the table 6.
However, in FIG. 3, the response of the current control unit 18 is omitted because the response is considered to be sufficiently faster than the position control unit 15 and the speed control unit 16.
[0019]
For example, when the position command for the table 6 is reversed from the positive direction to the negative direction, the position θL of the table 6 follows the position command value θr until immediately before the reversal, but the direction of the dynamic friction F acting on the table 6 at the time of reversal. Needs to move as much as the spring K expands and contracts.
Assuming that the displacement of the spring K is θL−θM, the transfer function from the dynamic friction F to θL−θM is given by the following equation (1).
θL−θM = J · F / ｛JL · JM · s²+ J ・ C ・ s + J ・ K｝
= [J ・ K / ｛JL ・ JM ・ s²+ J ・ C ・ s + J ・ K｝]
・ (F / K)
= B (s) · (F / K) (1)
Here, J = (JL + JM), (F / K) corresponds to the maximum backlash correction amount in the maximum backlash correction gain unit 12, and B (s) is a transfer function representing the time change of the maximum backlash correction amount. It is.
[0020]
Assuming that the transfer function from the position command value θr to the position θL of the table 6 is Q (s), the tracking error of the position θL of the table 6 with respect to the position command value θr is 1−Q (s).
Assuming that the speed controller 16 is V (s) = Kv (1 + Ki / s) and the position controller 15 is P (s) = Kp, the transfer function Q (s) is given by the following equation (2).
Q (s) = ｛JL ・ JM ・ s⁵+ (J ・ C + JL ・ Kv) s⁴
+ (JK + CKv + JLKvKi) s³
+ Kv (C · Kp + K + C · Ki) s²
+ Kv (C · Kp · Ki + K · Kp + K · Ki) s
+ K ・ Kp ・ Kv ・ Ki｝
/ [Kp · Kv ｛Cs²+ (K + C · Ki) s + K · Ki｝] (2)
[0021]
An error Δθ generated when the moving direction of the position command value θr with respect to the table 6 is reversed is given by the following equation (3).
Δθ = (1−Q (s)) · B (s) (3)
Therefore, if the transfer function corresponding to the equation (3) is set for the maximum backlash correction gain unit 12 and the transfer function filter 13, the error of the table 6 can be corrected.
When the response of the control system represented by Q (s) is slow, the transfer function represented by the following equation (4) is set in the transfer function filter 13 in consideration of the response delay. The error of the table 6 can be corrected with high accuracy.
Δθ / Q (s) = (1−Q (s)) · B (s) / Q (s) (4)
[0022]
For example, when K is sufficiently larger than JL, JM, and C, Equation (1) can be approximated by Equation (5) below.
B (s) = 1 (5)
Further, when the response of the speed control unit 16 can be considered to be sufficiently faster than that of the position control unit 15, the response Q (s) of the control system can be approximated by the following equation (6).
Q (s) = 1 / (s / Kp + 1) (6)
As described above, the transfer function filter 13 may be set to the transfer function given by the following equation (7) or (8).
(1−Q (s)) · B (s) = (s / Kp) / (s / Kp + 1) (7)
(1−Q (s)) · B (s) = s / Kp (8)
[0023]
When C and K are sufficiently larger than JL and JM, Expression (1) can be approximated by Expression (9) below.
B (s) = 1 / {(C / K) s + 1} (9)
Therefore, a transfer function given by the following equation (10) or (11) may be set in the transfer function filter 13.
(1−Q (s)) · B (s) = (s / Kp)
/ [｛C / (K · Kp)｝ s²+ ｛(C / K)
+ (1 / Kp)｝ s + 1] (10)
(1−Q (s)) · B (s) = s / [Kp {(C / K) s + 1}] (11)
[0024]
FIG. 4A shows the time response of the X-axis and the Y-axis when the robot is moved by giving a clockwise arc position command to two orthogonal X-Y axes, and FIG. The time response of the Y-axis command value near the quadrant switching is enlarged and displayed. The solid line indicates the position command value to which the backlash correction command value has been added, and the dotted line indicates the position command value before correction.
FIG. 4C illustrates a part of an arc when the feedback control is performed on the position command value without performing the backlash correction, with the error being enlarged and displayed. The solid line indicates the motion locus of the table 6, and the broken line indicates the motion locus of the servomotor 1. The movement trajectory of the table 6 indicated by the solid line is almost circular, but has a large protrusion at the lowermost end. This is a quadrant projection caused by a response delay.
FIG. 4D is an enlarged view of a part of the arc when the backlash correction is performed and the feedback control for the corrected position command is performed. The locus of the table 6 indicated by the solid line smoothly draws an arc even in the quadrant switching section.
[0025]
As is clear from the above, according to the first embodiment, when the control direction of the table 6 is reversed, the backlash correction command value is updated in accordance with the elapsed time from the occurrence of the reversal. Since the correction command value is added to the position command value and the rotation of the servo motor 1 for driving the table 6 is controlled based on the result of the addition, the elastic deformation that occurs when the moving direction of the table 6 is reversed is reduced. As a result, it is possible to compensate accurately, and as a result, there is an effect that the position θL of the table 6 can accurately follow the position command value θr.
[0026]
Further, according to the first embodiment, a correction torque amount for canceling the friction acting on the table 6 is determined in consideration of the control direction of the table 6, and a control signal of the servomotor 1 is generated in consideration of the correction torque amount. With such a configuration, even when the friction acting on the table 6 is large, there is an effect that the elastic deformation generated when the moving direction of the table 6 is reversed can be accurately compensated.
Further, according to the first embodiment, the transfer function filter 13 in which the transfer function from the friction acting on the table 6 to the deviation between the position θL of the table 6 and the position θM of the servomotor 1 is modeled. Is used to update the backlash correction command value, so that the elastic deformation that occurs when the moving direction of the table 6 is reversed does not need to be measured in advance by a sensor for the projection shape that occurs when no correction is made. Is achieved.
Further, according to the first embodiment, when the control direction of the table 6 is reversed, a predetermined amount of backlash is input to the transfer function filter 13, so that the table is not complicated. There is an effect that it is possible to accurately correct the elastic deformation that occurs when the moving direction of 6 is reversed.
[0027]
Embodiment 2 FIG.
5 is a block diagram showing a numerical control apparatus according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted.
The maximum backlash correction gain calculation unit 19 calculates a maximum backlash correction amount from the position command value generated by the position command generation unit 9 and adds the maximum backlash correction amount to the control direction signal output from the control direction detection unit 10. , And outputs the multiplication result to the transfer function filter 13 as a maximum backlash correction signal. The maximum backlash correction gain calculating section 19 constitutes a correction command value updating unit.
[0028]
FIG. 6 is an explanatory diagram illustrating a method of calculating the maximum backlash correction amount in the maximum backlash correction gain calculation unit 19.
The value of the dynamic friction F acting on the table 6 increases and decreases depending on the position, depending on how the machine is assembled. In the case of a structure in which the ball screw 4 is supported by bearings at both ends, dynamic friction is large at both ends, and is often small at the center. The relationship between the position command value θr and the dynamic friction F is measured in advance by a method of measuring a control current in the case of performing a constant-velocity linear motion, and is approximated by a function F (θr). In this case, for example, it is expressed by the following equation (12).
F (θr) = 1 / (a1 · θr + b1) + 1 / (a2 · θr + b2) (12)
Here, a1, a2, b1, and b2 are appropriate constants.
[0029]
The spring constant of the machine changes depending on the position. This is because the length from the servo motor 1 to the ball screw nut 5 changes depending on the position. The relationship between the position command value θr and the spring constant K is approximated by a function K (θr) based on the design data or measured values of the machine. In this case, for example, it is expressed by the following equation (13).
K (θr) = 1 / (a3 · θr + b3) (13)
Here, a3 and b3 are appropriate constants.
As described above, from the dynamic friction F (θr) and the spring constant K (θr) expressed as a function, the maximum backlash correction amount maxΔ is given by the following equation (14) as a function of the position command value θr.
maxΔ = F (θr) / K (θr) (14)
[0030]
Next, the operation will be described.
When receiving the position command value from the position command generator 9, the maximum backlash correction gain calculator 19 calculates a maximum backlash correction amount from the position command value.
For example, when the table 6 is at the end of the ball screw 4, the maximum backlash correction amount is increased as shown in FIG. 6, and when the table 6 is at the center of the ball screw 4, the maximum backlash correction amount is increased. Make it smaller.
Then, the maximum backlash correction gain calculator 19 receives the control direction signal from the control direction detector 10 and multiplies the control direction signal by the maximum backlash correction amount in the same manner as in the first embodiment. The result of the multiplication is output to the transfer function filter 13 as a maximum backlash correction signal.
[0031]
As is clear from the above, according to the second embodiment, the maximum backlash correction amount is calculated from the position command value generated by the position command generator 9 and the control direction signal output from the control direction detector 10 is calculated. Is multiplied by the maximum backlash correction amount, and the result of the multiplication is output to the transfer function filter 13. Therefore, when the elastic deformation generated when the moving direction of the table 6 is reversed changes according to the position. However, elastic deformation can be compensated with high accuracy, and as a result, the effect that the position θL of the table 6 can follow the position command value θr with high accuracy can be achieved.
[0032]
In the second embodiment, the relationship between the position command value θr and the maximum backlash correction amount maxΔ is represented by an approximation function. A similar effect can be obtained by using a calculation method of interpolating maxΔ.
[0033]
Embodiment 3 FIG.
FIG. 7 is a block diagram showing a numerical control apparatus according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG.
The friction estimating unit 20 estimates the friction acting on the table 6 from the position command value generated by the position command generating unit 9 and the corrected current command value (control signal) generated by the adder 17, and outputs the estimated friction signal. I do. The maximum backlash correction gain calculation unit 21 calculates a maximum backlash correction amount from the estimated friction signal output from the friction estimation unit 20 and the position command value generated by the position command generation unit 9, and calculates the maximum backlash correction amount. Output to the transfer function type filter 13. The friction estimator 20 and the maximum backlash correction gain calculator 21 constitute a correction command value updating unit.
[0034]
The friction estimating unit 20 calculates the estimated friction F # acting on the table 6 based on the following equation (15).
F ＾ = KT · i− {Jαr + Dωr + FM · sign (ωr)} (15)
Here, KT is a torque constant of the servo motor 1, i is a correction current command value including friction compensation, αr is an acceleration command value which is a second order differential value of the position command value θr, and ωr is a first order differential value of the position command value θr. , J (= JL + JM) is the total value of the moment of inertia of the mechanical system such as the table 6 and the servo motor 1, D is the total value of the viscous friction coefficient acting on the servo motor 1 and the table 6, and FM is the servo motor. The friction, sign (ωr), acting on 1 indicates a sign function that outputs “1” when ωr is positive and outputs “−1” when ωr is negative.
[0035]
The maximum backlash correction gain calculator 21 calculates the maximum backlash correction amount maxΔ based on the following equation (16).
maxΔ = F ＾ / K (θr) (16)
Here, F ＾ is the estimated friction output from the friction estimating unit 20, and K (θr) is a function representing the relationship between the position command value θr and the spring constant K.
[0036]
Next, the operation will be described.
Upon receiving the corrected current command value from the adder 17, the friction estimating unit 20 acts on the table 6 from the corrected current command value and the position command value generated by the position command generating unit 9 using Expression (15). Estimate the friction and output the estimated friction signal.
When receiving the estimated friction signal from the friction estimating unit 20, the maximum backlash correction gain calculating unit 21 calculates the maximum backlash from the estimated friction signal and the position command value generated by the position command generating unit 9 using Expression (16). The lash correction amount is calculated, and the maximum backlash correction amount is output to the transfer function filter 13.
[0037]
As is clear from the above, according to the third embodiment, the friction acting on the table 6 is estimated from the position command value generated by the position command generator 9 and the correction current command value generated by the adder 17. Since the maximum backlash correction amount is calculated from the estimated value and the position command value generated by the position command generation unit 9, and the maximum backlash correction amount is output to the transfer function filter 13, the table 6 is used. Even if the elastic deformation that occurs when the direction of movement of the motor changes is changed according to operating conditions such as position, speed, moving distance, arc radius, lubrication state of machine, and temperature, elastic deformation can be compensated with high accuracy. As a result, there is an effect that the position θL of the table 6 can be made to follow the position command value θr with high accuracy.
[0038]
Embodiment 4 FIG.
FIG. 8 is a block diagram showing a numerical control apparatus according to Embodiment 4 of the present invention. In the figure, the same reference numerals as those in FIG.
The friction compensation value calculation unit 22 multiplies the control direction signal output from the control direction detection unit 10 by the estimated friction signal output from the friction estimation unit 20, and sets the multiplication result as a current command correction value corresponding to the correction torque amount. Output to the adder 17. Note that the friction compensation value calculation unit 22 constitutes a control unit.
[0039]
Next, the operation will be described.
When receiving the control direction signal from the control direction detection unit 10, the friction compensation value calculation unit 22 multiplies the control direction signal by the estimated friction signal F # output from the friction estimation unit 20, and calculates the multiplication result as a correction torque amount. Is output to the adder 17 as a current command correction value corresponding to.
The adder 17 adds the current command value generated by the speed controller 16 and the current command correction value output from the friction compensation value calculator 22 to generate a corrected current command value.
[0040]
As is clear from the above, according to the fourth embodiment, the control direction signal output from control direction detection section 10 is multiplied by the estimated friction signal output from friction estimation section 20 and the multiplication result is corrected torque. Since the configuration is such that the current command correction value corresponding to the amount is output to the adder 17, the amount of friction acting on the table 6 depends on the operating conditions such as the position, speed, moving distance, arc radius, lubrication state of the machine, and temperature. Even if it changes accordingly, elastic deformation can be compensated with high accuracy, and as a result, there is an effect that the position θL of the table 6 can follow the position command value θr with high accuracy.
[0041]
【The invention's effect】
As described above, according to the present invention, when the control direction of the control target is reversed, the correction command value updating means for updating the backlash correction command value in accordance with the elapsed time since the inversion is provided, The configuration is such that the backlash correction command value updated by the correction command value updating means is added to the position command value, and the rotation of the motor driving the control target is controlled based on the addition result. There is an effect that the elastic deformation that occurs when the moving direction is reversed can be accurately compensated.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a numerical control device according to Embodiment 1 of the present invention.
FIG. 2 is an explanatory diagram illustrating elastic deformation generated between a servomotor and a table.
FIG. 3 is a block diagram showing a control system of the numerical control device according to the first embodiment.
FIG. 4 is an explanatory diagram illustrating an effect of suppressing a quadrant projection.
FIG. 5 is a configuration diagram showing a numerical control device according to a second embodiment of the present invention.
FIG. 6 is an explanatory diagram illustrating a method of calculating a maximum backlash correction amount in a maximum backlash correction gain calculation unit.
FIG. 7 is a configuration diagram showing a numerical control device according to Embodiment 3 of the present invention.
FIG. 8 is a configuration diagram showing a numerical control device according to Embodiment 4 of the present invention.
[Explanation of symbols]
Reference Signs List 1 servo motor, 2 encoder, 3 coupling, 4 ball screw, 5 ball screw nut, 6 table, 7 linear scale, 8 linear scale head, 9 position command generator, 10 control direction detector (control direction detector), 11 friction Compensation gain section (control means), 12 maximum backlash correction gain section (correction command value updating means), 13 transfer function type filter (correction command value updating means), 14 adder (control means), 15 position control section (control) Means, 16 speed control section (control means), 17 adder (control means), 18 current control section (control means), 19 maximum backlash correction gain calculation section (correction command value updating means), 20 friction estimation section ( Correction command value updating means), 21 maximum backlash correction gain calculating section (correction command value updating means), 22 friction compensation value calculation Outlet (control means).

Claims (7)

A control direction detecting means for monitoring a position command value of the control object to detect a control direction of the control object, and an elapsed time since the inversion occurs when the control direction detected by the control direction detection means is inverted. Correction command value updating means for updating the backlash correction command value in accordance with, and adding the backlash correction command value updated by the correction command value updating means to the position command value, based on the addition result. A numerical control device comprising: a control unit that controls rotation of a motor that drives the control target. The control means determines a correction torque amount for canceling friction acting on the controlled object in consideration of the control direction detected by the control direction detection means, and generates a motor control signal in consideration of the correction torque amount. The numerical control device according to claim 1, wherein The correction command value updating means uses a transfer function type filter in which a transfer function from friction acting on the controlled object to a deviation between the position of the controlled object and the position of the motor is corrected using a transfer function type filter. The numerical controller according to claim 1, wherein the value is updated. 4. The numerical controller according to claim 3, wherein the correction command value updating means inputs a predetermined amount of backlash to the transfer function type filter when the control direction detected by the control direction detecting means is reversed. 4. The correction command value updating means, when the control direction detected by the control direction detecting means is reversed, inputs a backlash amount corresponding to a position command value of a control target to a transfer function type filter. Numerical control device. The correction command value updating means estimates the friction acting on the control target from the position command value of the control target and the control signal of the motor, and when the control direction detected by the control direction detection means reverses, the estimated value of the friction and 4. The numerical controller according to claim 3, wherein a backlash amount is calculated from the position command value of the control target, and the backlash amount is input to a transfer function type filter. 3. The numerical control according to claim 2, wherein the control means estimates friction acting on the control object from a position command value of the control object and a control signal of the motor, and obtains a correction torque amount from the estimated value of the friction. apparatus.

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