JP2002258922A - Numerical control system - Google Patents

Abstract

(57) [Problem] To provide a numerical control system that accurately corrects a lost motion that fluctuates according to a position, a speed, and a lubrication state of a control target. SOLUTION: Inversion detecting means 7 for outputting inversion detection information according to increase / decrease of a position command value, and friction correction value calculation for generating a current command correction value based on the inversion detection information and a preset friction correction value. Means 9, a friction estimating means 8 for estimating the amount of friction based on the position information of the controlled object and the corrected current command value, and a lost motion correction value for generating a position command correction value based on the estimated friction amount Calculation means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control system applied to NC machining.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a block diagram showing a conventional numerical control system disclosed in Japanese Unexamined Patent Application Publication No. H10-209, in which 32 denotes an NC program 3.
1 is a function generator for calculating the movement information of the axis based on 1. Reference numeral 33 denotes an axis control unit that controls the axis based on the movement information of the axis. In the axis control unit 33, 34 is a main control unit, 35 is a control program storage unit, 36 is an output unit, 37
Is an input unit, 38 is a lost motion correction amount calculation unit, 39
Is a multilayer neural network type inference unit, and 40 is a connection weight coefficient calculation unit. 41 is a power amplifier, 42 is a servomotor, 43 is a motor position detector, 44 is a coupling,
5 is a table to be controlled, 46 is a coupling 44
Is a bed connected to the ball screw 47.

Next, the operation will be described. In a machine tool to which one of the numerical control systems is applied, it is required to improve both processing accuracy and productivity. A lost motion occurs in a feed drive mechanism mounted on a machine tool, which adversely affects the quality of machine processing. Therefore, measures for avoiding this have been considered. 12, a function generator 32 calculates axis movement information based on the NC program 31, and sends a position command SP to an axis controller 33.
To transfer. The main control unit 34 includes a position command SP, a servo control program SCP stored in a control program storage unit 35, and a motor position detection unit 43 that detects the rotor position of the servomotor 42 input via the input unit 37.
Based on the position detection value DP, calculation of each control loop of a desired position, speed, and current is performed, and finally, the current command value SI is transferred to the power amplifier 41 via the output unit 36.
The power amplifier 41 generates each phase voltage to be applied to the servomotor 42 according to the current command value SI. By applying this voltage, a driving torque is generated in the servo motor 42,
Via the coupling 44, the ball screw 46, the bed 4
7 is driven to drive the table 45 to be controlled at a desired position and speed.

Now, it is assumed that a position command SP requiring a lost motion correction process has been transferred from the function generator 32 to the axis controller 33. At this time, the main control unit 34 determines the current feed speed from the previous position command and the current position command, and the information is used as the multilayer neural network type inference unit 3.
9 is transferred. The position detection value DP obtained by the motor position detection unit 43 is also transferred to the multilayer neural network type inference unit 39 via the input unit 37, and the lubrication time and the elapsed time from the stop of lubricating oil supply. In the input layer of the multilayer neural network type inference unit 39, the speed, the position, the lubrication time, and the elapsed time from the stop of lubricating oil supply, which are thus measured at any time during machine operation, are input. Is output, and is transmitted to the lost motion correction amount calculation unit 38. The lost motion correction amount calculation unit 38 calculates a lost motion correction amount based on the lost motion generation amount and a preset lost motion correction reference amount, and transfers the lost motion correction amount to the main control unit 34. Is added to the position command data at the predetermined timing to correct the movement amount. The connection weight coefficient calculating unit 40 uses the lost motion measurement condition data of the speed, the position, and the shaft lubrication state measured in advance, and the lost motion measurement amount under the measurement conditions as teacher data. The layer inference unit 39 calculates each interlayer coupling weight coefficient.

[0005]

Since the conventional numerical control system is configured as described above, lost motion measurement is required under a wide range of conditions for learning the neural network. In addition, there is a problem that it is not possible to cope with aging, changes in the weight of the load, changes in room temperature, and the like.

The present invention has been made to solve the above-described problems, and accurately corrects a lost motion that fluctuates in accordance with a position, a speed, and a lubrication state of a control target without using a neural network. The purpose is to obtain a numerical control system.

[0007]

A numerical control system according to the present invention comprises: a reversal detecting means for outputting reversal detection information according to an increase or a decrease in a position command value; a reversal detection information and a preset friction correction value. A current command correction value generating means for generating a current command correction value based on the estimated friction amount; a friction estimating means for estimating a friction amount based on the position information of the control target and the corrected current command value; And a position command correction value generating means for generating a position command correction value.

In the numerical control system according to the present invention, the position command correction value generating means generates a position command correction value based on the amount of friction estimated by the friction estimating means and the position command value output from the position command value output means. Is generated.

A numerical control system according to the present invention includes a friction estimating means for estimating a friction amount based on position information of a control object and a corrected current command value, and a position command correction value based on the estimated friction amount. And a current command correction value generating means for generating a current command correction value based on the estimated amount of friction.

In the numerical control system according to the present invention, the current command correction value generating means generates a current command correction value based on the reversal detection information detected by the reversal detecting means and the friction amount estimated by the friction estimating means. It is something to do.

In the numerical control system according to the present invention, the friction estimating means estimates the amount of friction based on the position information of the control target and the current command value corrected by the current command value correcting means, and the estimated friction The output is limited so that the absolute value of the amount does not exceed a preset maximum friction amount.

In a numerical control system according to the present invention, the friction estimating means estimates the amount of friction in consideration of the effect of gravity when the movement direction of the control target is affected by gravity. It is.

In the numerical control system according to the present invention, in the position command correction value generating means, the position command is obtained by dividing the amount of friction from the friction estimating means by the position command value and the rigidity of the non-linear spring element that changes according to the amount of friction. A correction value is generated.

A numerical control system according to the present invention is based on a position information of a control target when the control target is operated based on a fixed position command value and a current command value to a driving means for driving the control target. A parameter estimating means for estimating the moment of inertia and the coefficient of viscous friction of the controlled object. The friction estimating means uses the output of the parameter estimating means to output position information of the controlled object and drive means for driving the controlled object. The friction amount is estimated based on the current command value.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 shows N according to Embodiment 1 of the present invention.
1 is a block diagram showing the configuration of one axis of a C machining system. In the figure, reference numeral 1 denotes a table (an object to be controlled) to which a workpiece or a tool is fixed, and 2 denotes a ball screw nut fixed to a lower surface of the table 1. (Drive means) 3, a ball screw (drive means) fitted with the ball screw nut 2, 4 a servo motor (drive means) for rotating the ball screw 3, and 5 a rotation amount of the servo motor 4 is detected. It is an encoder. The ball screw 3 and the ball screw nut 2 convert the rotational motion of the servo motor 4 into a linear motion. The table 1 includes a drive transmitting member such as the ball screw 3 and the ball screw nut 2 and a linear motion guide mechanism (guide rail) not shown. The position is controlled to be set to a predetermined position, or the moving operation is performed on the target trajectory. 6 is a position command value output means for outputting a position command value for numerically controlling the position of the table 1 in a predetermined one axis direction based on a machining program or the like, and 7 is an axis of the table 1 based on the increase or decrease of the position command value. It is determined whether or not the control direction of the direction is reversed. If the direction is reversed, stepwise reversal detection information having a positive or negative magnitude 1 corresponding to an increase or decrease of the position command value after the reversal is output, and the reversal is not performed. In this case, the inversion detection means outputs step-like inversion detection information having the same sign as the previous determination result and having the same size as 1. Numeral 8 denotes a friction estimating means for estimating the amount of friction acting on the control target based on the corrected current command value for the servo motor 4 and the rotation amount of the servo motor 4 output from the encoder 5 using the following equation (1). . f = Kt × ir−J × ddθ−C × dθ (1) where f is the estimated amount of friction in terms of the servo motor shaft, K
t is the torque constant of the servo motor 4, ir is the current command value to the servo motor 4, J is the moment of inertia in terms of the servo motor axis including all movable parts, ddθ is the angular acceleration of the servo motor 4, and C is the servo motor axis conversion. Coefficient of viscous friction, dθ
Is the angular velocity of the servo motor 4. Note that the above equation (1)
Since the value calculated in (1) often contains high-frequency noise, a value passed through a low-pass filter is output as the estimated amount of friction. Reference numeral 9 denotes a friction correction value calculation unit (current command correction value generation unit) for integrating a preset friction correction value with the reversal detection information from the reversal detection unit 7 to calculate a current command correction value. A lost motion correction value calculation means (position command correction value generation means) for calculating a position command correction value using the following equation (2) based on the amount of friction from. LM = f / K (2) where LM is the calculated lost motion correction value (position command correction value), f is the amount of friction estimated by the friction estimating means 8, and K is the driving force of the ball screw 3 or the like. It is the rigidity of the spring element included in the transmission system. Reference numeral 11 denotes a position command value correction unit that adds a position command correction value to the position command value. Reference numeral 12 denotes the distance between the target position indicated by the output of the position command value correcting means 11 and the current position indicated by the detected rotation amount of the encoder 5, to which the output of the position command value correcting means 11 and the detected rotation amount of the encoder 5 are input. Position control means (current command value generating means) for outputting a speed command corresponding to the speed command; 13 speed control means (current command value generating means) for outputting a current command value to the servomotor 4 according to the speed command value; Reference numeral 14 denotes a current command value correcting means for adding a current command correction value which is an output of the friction correction value calculating means 9 to the current command value, and reference numeral 15 denotes an input of the output of the current command value correcting means 14, which responds to the output. This is current control means for supplying a current to the servo motor 4.

Next, the operation will be described. When a position command value is output from the position command value output means 6 based on a machining program or the like, the reversal detection means 7 determines whether or not the control direction in the axial direction of the table 1 is reversed based on the increase or decrease of the position command value. Judge. Then, if not inverted, the same sign as the previous determination result is output, and if inverted, positive or negative stepwise inversion detection information having a magnitude of 1 according to the control direction of the inverted axis is output. . Further, the friction estimating means 8 estimates the friction amount of the table 1 based on the rotation amount and the current command value detected by the encoder 5, and the lost motion correction value calculating means 10 calculates the lost motion from the estimated friction amount. The correction value is calculated and output as a position command correction value, and the position command value correction means 11 adds the position command correction value and the position command value. Then, the position control means 12 outputs a speed command value corresponding to the distance between the target position indicated by the corrected position command value and the current position indicated by the rotation amount detected by the encoder 5,
The speed control means 13 outputs a current command value according to the speed command value. Furthermore, the friction correction value calculation means 9 outputs a current command correction value by integrating a preset friction correction value to the inversion detection information, and the current command value correction means 14 applies the current command correction value to the current command value. The current control means 15 adds
A current corresponding to the corrected current command value is supplied to the servo motor 4. Then, the servo motor 4 drives the ball screw 3 to rotate, and the table 1 moves to the position of the position command value at the speed of the speed command together with the ball screw nut 2.

As described above, according to the first embodiment, the position command value is input, the reversal detecting means 7 detects the reversal of the control direction based on the increase or decrease of the position command value, and outputs reversal detection information. And a friction estimating means 8 for estimating and outputting the amount of friction based on the current command value for the servomotor 4 and the current position of the table 1, and a position command correction value which changes according to the amount of friction from the friction estimating means 8. A lost motion correction value calculation means 10 for generating and outputting, and a position command correction means 11 for performing a correction operation of the position command value using the position command correction value, the position command used for numerical control of the table 1 Since the value is corrected, the position command value can be corrected using an appropriate position command correction value according to the current state of the control target. Therefore, different amounts of friction can be obtained in accordance with the position, speed, and lubrication state of the table 1, and the position command value can be corrected based on the amount. Therefore, play due to the play between the ball screw nut 2 and the ball screw 3 is caused. Even if there is backlash or elastic deformation depending on the relationship between the stiffness and friction of these drive transmission members, a fixed position command correction value is simply used when the control direction of the table 1 is reversed. As compared with the case where the position command value is corrected, the lost motion can be corrected more accurately, and the position can be controlled more accurately.

Embodiment 2 FIG. FIG. 2 is a block diagram showing a configuration of one axis of an NC machining system according to a second embodiment of the present invention. In FIG.
Lost motion correction value calculating means (position command correction) for calculating a position command correction value using the following equation (3) based on the friction amount estimated from the position command value and the position command value from the position command value output means 6. Value generating means). LM = f / K (θ) (3) where LM is the calculated lost motion correction value, f is the friction amount estimated by the friction estimating means 8, θ is a position command value (rotation amount), K (θ) is different for each position.
Stiffness of the spring element included in the driving force transmission system.
The other configuration is the same as that of the first embodiment, and the description is omitted.

Next, the operation will be described. The lost motion correction value calculation means 16 calculates a stiffness K (θ) of a spring element that differs for each position command value by a function or a table lookup based on the position command value θ from the position command value output means 6. Next, the lost motion correction value LM is calculated by dividing the friction amount f estimated by the friction estimating means 8 by the spring stiffness K (θ), and is output as a position command correction value. Other operations are the same as those in the first embodiment, and a description thereof will be omitted.

As described above, according to the second embodiment, the lost motion correction value calculating means 16 corrects the position command based on the amount of friction estimated by the friction estimating means 8 and the spring stiffness which differs for each position. Since the value is output, it is possible to calculate an appropriate position command correction value even if the actual amount of friction fluctuates depending on the position, speed, and movement distance, or if the spring stiffness of the driving force transmission system fluctuates according to the position. Therefore, the lost motion can be corrected more accurately and the position can be controlled more accurately than when the position command value is corrected using a fixed position command correction value when the control direction of the table 1 is reversed. Can be.

Embodiment 3 FIG. 3 is a block diagram showing a configuration of one axis of an NC machining system according to a third embodiment of the present invention. In FIG.
Is a friction correction value calculation means (current command correction value generation means) which converts the estimated friction amount from the current value into a current value and outputs it as a friction correction value. The other configuration is the same as that of the second embodiment, and the description is omitted.

Next, the operation will be described. When the friction amount estimated from the friction estimating unit 8 is input, the friction correction value calculating unit 17 converts this into a current value and outputs it as a friction correction value. Other operations are the same as those in the second embodiment, and a description thereof will be omitted.

As described above, according to the third embodiment, the output of the amount of friction from the friction estimating means 8 is
Correction value calculating means 1 which converts the current into a current and outputs the current
7, the increase or decrease in the amount of friction that changes in accordance with the position, speed, or lubrication state of the table 1 can be offset by the estimated amount of friction, and the positional accuracy deteriorates due to the increase or decrease in the amount of friction. Can be prevented.

Embodiment 4 FIG. 4 is a block diagram showing a configuration of one axis of an NC machining system according to a fourth embodiment of the present invention. In FIG. A friction correction value calculation unit (current command correction value generation unit) that compares the value obtained by multiplying the sign with the friction amount estimated by the friction estimation unit 8 and outputs the larger absolute value as a friction correction value. . The other configuration is the same as that of the second embodiment, and the description is omitted.

Next, the operation will be described. When the inversion detection information is input from the inversion detection means 7, the friction correction value calculation means 18 multiplies a preset friction correction value by the sign of the inversion detection information from the inversion detection means 7 and the friction estimation means 8. Is compared with the estimated friction amount, and the larger absolute value is output as a friction correction value. Other operations are the same as those in the second embodiment, and a description thereof will be omitted. FIG. 5 is an explanatory diagram showing the operation of the friction correction value calculating means 18. When the moving direction of the controlled object in (a) reverses at high speed, the friction acting on the controlled object indicated by the thin line has a small absolute value, and
The sign is reversed at high frequencies. In such a case, since the friction estimation means 8 includes a low-pass filter,
The sign of the estimated amount of friction indicated by the dotted line is inverted with a delay after the actual friction. On the other hand, indicated by the dashed
The correction signal obtained by multiplying a preset friction correction value by a value equivalent to the actual friction during high-speed movement and the sign of the inversion detection information from the inversion detection means 7 has a sign that is not delayed from the actual friction. Is inverted. While the estimated amount of friction is delayed by the low-pass filter, its absolute value is small. Therefore, the friction correction value calculating unit 18 outputs a friction correction value generated from inversion detection information having a large absolute value. Therefore, the output of the friction correction value calculating means 18 does not have a large delay with respect to the friction acting on the controlled object.
In the case where the moving direction of the controlled object in (b) reverses at a low speed, the absolute value of the friction acting on the controlled object indicated by the thin line is large and the sign is gradually inverted. In such a case, the delay caused by the low-pass filter included in the friction estimating means 8 is not large. In addition, while the estimated absolute value of the friction amount is small, the friction correction value generated from the inversion detection signal is output, so that the delay is reduced.

As described above, according to the fourth embodiment, the friction correction value calculating means 18 is generated from the friction amount estimated by the friction estimating means 8 and the inversion detection information from the inversion detecting means 7. Because the absolute value of the friction correction value that is larger is output, the response delay of the output does not increase regardless of whether the sign of the friction acting on the controlled object is high or low. It is possible to accurately correct a quadrant projection caused by friction that varies according to the lubrication state of the control target.

Embodiment 5 FIG. FIG. 6 is a block diagram showing a configuration of one axis of the NC processing system according to the fifth embodiment of the present invention. In FIG. 6, reference numeral 19 denotes a preset friction correction value of the reverse detection information from the reverse detecting means 7. Friction correction value calculation means (current command correction value generation means) for outputting a sum of a value obtained by multiplying the sign and a value obtained by multiplying the friction amount estimated by the friction estimation means 8 by a preset gain as a friction correction value. It is. The other configuration is the same as that of the second embodiment, and the description is omitted.

Next, the operation will be described. When an inversion detection signal is input from the inversion detection means 7, the friction correction value calculation means 19 multiplies a preset friction correction value by the sign of the inversion detection information from the inversion detection means 7 and the friction estimation means 8 Is added to a value obtained by multiplying the amount of friction estimated in (1) by a preset gain and output as a friction correction value. Other operations are the same as those in the second embodiment, and a description thereof will be omitted. FIG. 7 is an explanatory diagram showing the operation of the friction correction value calculating means 19. When the moving direction of the controlled object in (a) reverses at high speed, the friction acting on the controlled object indicated by the thin line has a small absolute value, and the sign is inverted at a high frequency. In such a case, since a low-pass filter is included in the friction estimating means 8, a signal obtained by multiplying the estimated amount of friction indicated by a dotted line by a preset gain has a sign that is significantly delayed from the actual friction and the sign is inverted. I do. On the other hand, indicated by a dashed line,
The correction signal obtained by multiplying a preset friction correction value by a value smaller than the actual friction during high-speed movement and the sign of the inversion detection information from the inversion detection means 7 has a sign that is not delayed from the actual friction. Is inverted. As described above, the friction correction value calculated from the estimated friction amount includes the response delay, but the friction correction value generated from the reversal detection information is added thereto. The delay included in the output is reduced. In the case where the moving direction of the controlled object in (b) reverses at a low speed, the absolute value of the friction acting on the controlled object indicated by the thin line is large and the sign is gradually inverted. In such a case, the delay caused by the low-pass filter included in the friction estimating means 8 is not large. In addition, since the friction correction value generated from the inversion detection information is added,
The delay included in the output of the friction correction value calculation means 19 is reduced.

As described above, according to the fifth embodiment, the friction correction value calculating means 19 multiplies the friction amount estimated by the friction estimating means 8 by a predetermined gain.
Since the friction correction value obtained by adding the friction correction value generated from the reversal detection information from the reversal detection means 7 is output, the response delay of the output is reduced regardless of whether the sign of the friction acting on the control target is high or low. It does not become large, and it is possible to accurately correct quadrant projections caused by friction that varies depending on the position, speed, and lubrication state of the control target.

Embodiment 6 FIG. FIG. 8 is a block diagram showing a configuration of one axis of an NC processing system according to a sixth embodiment of the present invention.
Is a friction estimating means for estimating the amount of friction acting on the control object using the following equations (4) and (5) based on the current command value for the motor and the rotation amount of the servo motor 4 output from the encoder 5. f1 = Kt × ir−J × ddθ−C × dθ (4) if (f1> Fmax) f = Fmax else if (f1 <−Fmax) f = −Fmax (5) where f is Estimated friction amount of servo motor shaft conversion, K
t is the torque constant of the servo motor 4, ir is the current command value to the servo motor 4, J is the moment of inertia in terms of the servo motor axis including all movable parts, ddθ is the angular acceleration of the servo motor 4, and C is the servo motor axis conversion. Coefficient of viscous friction, dθ
Is the angular velocity of the servomotor 4, and Fmax is the assumed maximum amount of friction. Since the value calculated by the above equation (5) often includes high-frequency noise, a value passed through a low-pass filter is output as the estimated amount of friction. The other configuration is the same as that of the fourth embodiment, and the description is omitted.

Next, the operation will be described. When the corrected current command value from the current command value correcting means 14 and the rotation amount of the servo motor 4 from the encoder 5 are input, the friction estimating means 20 uses the above equations (4) and (5). The calculated value is passed through a low-pass filter to remove noise, and the estimated friction amount is output. Other operations are the same as those in the fourth embodiment, and a description thereof will not be repeated.

As described above, according to the sixth embodiment, the friction estimating means 20 determines the correction value based on the corrected current command value from the current command value correcting means 14 and the rotation amount of the servo motor 4 from the encoder 5. In order to limit the output so that the absolute value of the estimated frictional amount calculated by the above does not exceed the assumed maximum frictional amount Fmax, even when the control target collides with a stationary object, the estimated frictional amount does not abnormally increase. It is possible to prevent the lost motion correction value and the friction correction value from abnormally increasing.

Embodiment 7 FIG. 9 is a block diagram showing a configuration of one axis of an NC processing system according to a seventh embodiment of the present invention.
Is a friction estimating means for estimating the amount of friction acting on the control target using the following equation (6), based on the current command value for the motor and the rotation amount of the servo motor 4 output from the encoder 5. f1 = Kt × ir−J × ddθ−C × dθ−G (6) where f1 is the estimated amount of friction in terms of the servo motor shaft,
Kt is a torque constant of the servo motor 4, ir is a current command value to the servo motor 4, J is a moment of inertia in terms of a servo motor axis including all movable parts, ddθ is an angular acceleration of the servo motor 4, and C is a servo motor axis conversion. Coefficient of viscous friction, d
θ is the angular velocity of the servo motor 4, and G is the torque obtained by multiplying the mass of the movable part by the gravitational acceleration. Since the value calculated by the above equation (6) often includes high-frequency noise, a value passed through a low-pass filter is output as the estimated amount of friction. The other configuration is the same as that of the fourth embodiment, and the description is omitted.

Next, the operation will be described. When the corrected current command value from the current command value correcting means 14 and the rotation amount of the servo motor 4 from the encoder 5 are input, the friction estimating means 21 converts the value calculated using the above equation (6) into a low-pass The noise is removed through a filter, and the estimated amount of friction is output. Other operations are the same as those in the fourth embodiment, and a description thereof will not be repeated.

As described above, according to the seventh embodiment, when the motion direction of the controlled object is affected by gravity, the friction estimating means 21 determines the amount of friction in consideration of the effect of gravity. Since the estimation is performed, the friction can be estimated with high accuracy even when gravity is exerted on the control target.

Embodiment 8 FIG. FIG. 10 is a block diagram showing a configuration of one axis of the NC machining system according to the eighth embodiment of the present invention. In the drawing, reference numeral 22 denotes a position command value from the position command value output unit 6 and a position command value from the inversion detection unit 7. Lost motion correction value calculation means (position command correction value generation means) for calculating a position command correction value using the following equations (7) and (8) based on the inversion detection information and the amount of friction from friction estimation means 21 It is. LM = f / (K (θ) · kf (f)) (7) if (| f |> F1) kf = kf1 else kf = kf2 (8) where LM is the calculated lost The motion correction value, f is the amount of friction estimated by the friction estimating means 21, θ is the current position (rotation amount) of the servo motor 4, and K (θ) is the function of the spring element for each current position expressed as a table or a table. rigidity,
kf (f) is a non-linear characteristic of the spring element. When the friction amount f is small, the rigidity of the spring element is small, and when the friction amount f is large, the rigidity of the spring element is large. The other configuration is the same as that of the fourth embodiment, and the description is omitted.
In the eighth embodiment, the non-linear characteristic of the spring element is expressed by the above equation (8). However, the same effect can be obtained by expressing it by another function or a table.

Next, the operation will be described. When the estimated friction amount from the friction estimating unit 21, the position command value from the position command value output unit 6, and the inversion detection information from the inversion detection unit 7 are input, the lost motion correction value calculation unit 22 The lost motion correction value is calculated using Expressions (7) and (8), multiplied by the sign of the inversion detection information, and output. Other operations are the same as those in the fourth embodiment, and a description thereof will not be repeated.

As described above, according to the eighth embodiment, the lost motion correction value calculating means 22 uses the equations (7) and (8) based on the estimated friction amount and the position command value. Since the lost motion correction value is calculated, even when the spring stiffness of the driven object has nonlinearity, it is possible to calculate the correction value in consideration of the characteristic,
Highly accurate correction is possible.

Embodiment 9 FIG. 11 is a block diagram showing a configuration of one axis of the NC machining system according to the ninth embodiment of the present invention. In FIG. 11, reference numeral 23 denotes a position command value output means 6 for outputting a predetermined position command value. And a corrected current command value which is an output of the current command value correcting means 14 during movement of the controlled object based on the position command value, and a rotation amount of the servo motor 4 which is an output of the encoder 5. From the following equation (9) using the method of least squares, a value obtained by multiplying the inertia moment J in terms of the servo motor axis including all the movable parts, the viscous friction coefficient C in terms of the servo motor axis, and the mass of the movable part by the gravitational acceleration is given. This is a parameter estimating means that calculates the torque G and outputs it to the friction estimating means 21. [J C fe G] = (B′B) ＾ − 1 B ′ [τ] B = [ddθ dθ sign (dθ) 1] τ = Kt × i (9) where [] ′ is a transposed matrix , [] ＾ − 1 is the inverse matrix, [τ]
Is a column vector of m rows composed of time series data of the command torque to the servo motor 4, and B is the angular acceleration ddθ and the angular velocity dθ.
A time-series data of sign (dθ) and a matrix of m rows and 4 columns in which all elements are 1 column vectors, f
e is the average value of the fluctuating friction. The other configuration is the same as that of the eighth embodiment, and the description is omitted.

Next, the operation will be described. When the physical parameter of the control target is changed due to, for example, replacement of a workpiece mounted on the table of the control target, the parameter estimating unit 23 issues an instruction to the position command value output unit 6 to output a parameter for parameter measurement. A position command value is generated, and a parameter is calculated from the corrected current command value during movement of the controlled object based on the position command value and the rotation amount of the servo motor 4 using the above equation (9). The friction estimating means 21 performs subsequent friction estimation calculations using the calculated parameters. Other operations are the same as those in the eighth embodiment, and a description thereof will not be repeated.

As described above, according to the ninth embodiment, the parameter estimating means 23 causes the position command value output means 6 to generate a position command value for parameter estimation as necessary, and based on the position command value. The corrected current command value and the rotation amount of the servomotor 4 during the movement of the controlled object are measured, and the parameters used by the friction estimating means 21 are calculated and updated. Even when the physical parameter of the control target is changed due to the exchange of the work or the like, the parameter can be easily updated, accurate friction estimation can be always performed, and highly accurate correction can be performed.

[0042]

As described above, according to the present invention, the inversion detecting means for outputting the inversion detection information according to the increase or decrease of the position command value, and the inversion detection means based on the inversion detection information and the preset friction correction value. Current command correction value generating means for generating a current command correction value; friction estimating means for estimating a friction amount based on position information of a control target and a corrected current command value; and a position estimating unit based on the estimated friction amount. Since the current command correction value generating means is provided with the position command correction value generating means for generating the command correction value, the current command correction value generating means is provided by the friction which fluctuates according to the position / speed / lubrication state of the control target. Quadrant projections can be accurately corrected. Also, by providing the position command correction value generation means, the position / speed /
There is an effect that lost motion that fluctuates according to the lubrication state of the control target can be accurately corrected.

According to the present invention, the position command correction value generating means generates the position command correction value based on the amount of friction estimated by the friction estimating means and the position command value output from the position command value output means. With such a configuration, the provision of the position command correction value generation means allows the lost motion to vary according to the position, speed, and lubrication state of the controlled object even when the rigidity of the drive means varies according to the position. Can be corrected with high accuracy.

According to the present invention, the friction estimating means for estimating the amount of friction based on the position information of the control object and the corrected current command value, and the position command correction value is generated based on the estimated amount of friction. Since it is configured to include the position command correction value generation unit and the current command correction value generation unit that generates the current command correction value based on the estimated amount of friction, by providing the position command correction value generation unit, Lost motion that fluctuates depending on the position, speed, and lubrication state of the control target can be accurately corrected. Further, the provision of the current command correction device has an effect of accurately correcting a quadrant projection caused by friction that varies depending on the position, speed, and lubrication state of the control target.

According to the present invention, the current command correction value generating means generates the current command correction value based on the reversal detection information detected by the reversal detecting means and the friction amount estimated by the friction estimating means. With the provision of the current command correction value generating means, the output response delay does not increase regardless of whether the sign of the friction acting on the controlled object is high or low, and the position / speed is always constant. There is an effect that the quadrant projection caused by the friction that fluctuates according to the lubrication state of the control target can be accurately corrected.

According to this invention, the friction estimating means estimates the amount of friction based on the position information of the control target and the current command value corrected by the current command value correcting means, and calculates the absolute value of the estimated friction amount. Since the output is limited so that the value does not exceed the preset maximum friction amount, the control target collides with another object by the friction estimating means, and the current command to the driving means for driving the control target is given. Even when the values become abnormally large, there is an effect that the position command correction value and the current command correction value do not become abnormal values.

According to the present invention, when the movement direction of the controlled object is affected by gravity, the friction estimating means is configured to estimate the amount of friction in consideration of the effect of gravity. The estimating means makes it possible to accurately estimate the friction even when gravity affects the controlled object, and as a result, there is an effect that the position command value and the current command value can be accurately corrected.

According to the present invention, the position command correction value generating means divides the amount of friction from the friction estimating means by the position command value and the stiffness of the non-linear spring element which changes according to the friction amount. Since it is configured to generate the position command correction value, the position command correction value generation unit can accurately generate the position command correction value even when the control target has a characteristic as a non-linear spring element.

According to the present invention, the control is performed based on the position information of the control target when the control target is operated based on the fixed position command value and the current command value to the driving means for driving the control target. A parameter estimating means for estimating a moment of inertia and a viscous friction coefficient of the object; the friction estimating means uses the output of the parameter estimating means to obtain position information of the controlled object and a current command value to a driving means for driving the controlled object; Is configured to estimate the amount of friction on the basis of the above, so that even when the load mass of the controlled object changes, the moment of inertia and the viscous friction coefficient of the controlled object can be easily estimated by the parameter estimating means. In addition, there is an effect that the position command value and the current command value can be accurately corrected with the estimated parameters.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of one axis of an NC processing system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of one axis of an NC processing system according to a second embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of one axis of an NC processing system according to a third embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of one axis of an NC processing system according to a fourth embodiment of the present invention;

FIG. 5 is an explanatory diagram showing an operation of a friction correction value calculating unit.

FIG. 6 is a block diagram showing a configuration of one axis of an NC processing system according to a fifth embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an operation of a friction correction value calculating means.

FIG. 8 is a block diagram showing a configuration of one axis of an NC processing system according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of one axis of an NC processing system according to a seventh embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of one axis of an NC processing system according to an eighth embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of one axis of an NC processing system according to a ninth embodiment of the present invention.

FIG. 12 is a block diagram showing a conventional numerical control system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Table (control object), 2 ball screw nuts (drive means), 3 ball screws (drive means), 4 servo motors (drive means), 5 encoders, 6 position command value output means, 7 inversion detection means, 8, 20, 21 Friction estimation means, 9, 17 to 19 friction correction value calculation means (current command correction value generation means), 10, 16, 22 lost motion correction value calculation means (position command correction value generation means), 11 position command value correction means, 12 position control means (current command value generation means), 13 speed control means (current command value generation means), 14 current command value correction means, 15 current control means, 23 parameter estimation means.

Claims (8)

[Claims] 1. A position command value correction means for correcting a position command value output from a position command value output means with a position command correction value, and a current command based on the position command value corrected by the position command value correction means. Current command value generation means for generating a value, current command value correction means for correcting the current command value generated by the current command value generation means with a current command correction value, and current corrected by the current command value correction means Current control means for supplying a current based on a command value to a driving means for driving a control object; and reversal detection by detecting reversal of the control direction in accordance with an increase or decrease in the position command value output from the position command value output means. A current command correction value based on the reversal detection information detected by the reversal detection means and a preset friction correction value; Current command correction value generation means for supplying to the positive means, friction estimation means for estimating the amount of friction based on the position information of the control object and the current command value corrected by the current command value correction means, and the friction estimation Generating a position command correction value based on the friction amount estimated by the means,
A numerical control system comprising: a position command correction value generation unit that supplies the position command value to the position command value correction unit. 2. The position command correction value generating means generates a position command correction value based on the friction amount estimated by the friction estimating means and the position command value output from the position command value output means. 2. The numerical control system according to claim 1, wherein the numerical control is supplied to a correction unit. 3. A position command value correction means for correcting a position command value output from a position command value output means with a position command correction value, and a current command based on the position command value corrected by the position command value correction means. Current command value generation means for generating a value, current command value correction means for correcting the current command value generated by the current command value generation means with a current command correction value, and current corrected by the current command value correction means A current control unit that supplies a current based on the command value to a driving unit that drives the control target; and a friction amount is estimated based on the position information of the control target and the current command value corrected by the current command value correction unit. Friction estimating means, and a position command correction value generating means for generating a position command correction value based on the amount of friction estimated by the friction estimating means and supplying the position command correction value to the position command value correcting means. A current command correction value generating means for generating a current command correction value based on the amount of friction estimated by the friction estimating means and supplying the current command correction value to the current command value correcting means. 4. The current command correction value generation means generates a current command correction value based on the reversal detection information detected by the reversal detection means and the amount of friction estimated by the friction estimation means. The numerical control system according to claim 1, wherein the numerical control is supplied to a computer. 5. A friction estimating means for estimating a friction amount based on position information of a control target and a current command value corrected by the current command value correcting means, and an absolute value of the estimated friction amount is set in advance. The numerical control system according to any one of claims 1 to 4, wherein the output is limited so as not to exceed the set maximum friction amount. 6. The apparatus according to claim 1, wherein the friction estimating means estimates the amount of friction in consideration of the influence of gravity when the movement direction of the controlled object is affected by gravity. The numerical control system according to any one of claims 5 to 13. 7. The position command correction value generating means generates a position command correction value obtained by dividing the amount of friction from the friction estimating means by the position command value and the stiffness of a nonlinear spring element that changes according to the amount of friction. The numerical control system according to any one of claims 1 to 6, wherein: 8. An inertia moment of a controlled object based on position information of the controlled object when the controlled object is operated based on a fixed position command value and a current command value to a driving unit for driving the controlled object. And a parameter estimating means for estimating a viscous friction coefficient, wherein the friction estimating means uses the output of the parameter estimating means based on positional information of the controlled object and a current command value to a driving means for driving the controlled object. The numerical control system according to any one of claims 1 to 7, wherein the amount of friction is estimated by using a numerical value.