阅读说明：本技术 伺服电动机控制装置 (Servo motor control device ) 是由 广瀬登 辻川敬介 于 2020-03-26 设计创作，主要内容包括：本发明提供伺服电动机控制装置。具备：位置指令制作部,制作用于确定由伺服电动机驱动的被驱动体的目标位置的位置指令；反力指令制作部,制作用于确定被驱动体应受到的目标反力的反力指令；位置获取部,获取被驱动体的实际的位置；位置基准驱动控制部,生成位置基准驱动信号以使该位置接近目标位置；反力获取部,获取被驱动体受到的反力；反力基准驱动控制部,生成反力基准驱动信号以使该反力接近目标反力；以及驱动信号选择部,选择位置基准驱动信号和反力基准驱动信号中的任一个信号,位置指令制作部以使目标位置相对于时间成为二次以上的关系的方式制作位置指令,反力指令制作部以使目标反力与目标位置的关系呈大致线性的方式制作反力指令。(The invention provides a servo motor control device. The disclosed device is provided with: a position command generating unit that generates a position command for specifying a target position of a driven body driven by the servo motor; a reaction force command generating unit that generates a reaction force command for specifying a target reaction force to be applied to the driven body; a position acquisition unit that acquires an actual position of the driven body; a position reference drive control unit that generates a position reference drive signal to cause the position to approach a target position; a reaction force acquisition unit that acquires a reaction force applied to the driven body; a reaction force reference drive control unit that generates a reaction force reference drive signal so that the reaction force approaches a target reaction force; and a drive signal selection unit that selects either one of the position reference drive signal and the reaction force reference drive signal, wherein the position command generation unit generates the position command such that the target position is in a quadratic or more relationship with respect to time, and the reaction force command generation unit generates the reaction force command such that the relationship between the target reaction force and the target position is substantially linear.)

1. A servo motor control device is provided with:

a position command generating unit that generates a position command for specifying a target position to be located at by time a driven body driven by a servo motor;

a reaction force command generating unit that generates a reaction force command for specifying a target reaction force to be applied to the driven body by driving the servo motor, for each period of time;

a position acquisition unit that acquires an actual position of the driven body;

a position reference drive control unit that generates a position reference drive signal for driving the servo motor so that the position acquired by the position acquisition unit approaches the target position;

a reaction force acquisition unit that acquires a reaction force actually received by the driven body;

a reaction force reference drive control unit that generates a reaction force reference drive signal for driving the servo motor so that the reaction force acquired by the reaction force acquisition unit approaches the target reaction force; and

a drive signal selection unit that selects either one of the position reference drive signal and the reaction force reference drive signal,

wherein the position command creating unit creates the position command such that the target position has a relationship of two or more times with respect to time,

the reaction force command generating unit generates the reaction force command such that a relationship between the target reaction force and the target position is substantially linear.

2. The servomotor control device according to claim 1, wherein,

the correlation coefficient between the time at which the target position is reached and the time at which the target reaction force is reached is equal to or greater than the ratio of the gain of the position reference drive control unit to the gain of the reaction force reference drive control unit.

3. The servomotor control device according to claim 1 or 2, wherein,

the position command generating unit calculates the target position as a time function of at least two,

the reaction force command creating unit calculates the target reaction force as a time function having the same frequency as that of the time function of the target position.

4. The servomotor control device according to any one of claims 1 to 3, wherein,

the reaction force command creating unit creates the reaction force command so that the target reaction force precedes the target position in the position command by a fixed value.

5. The servomotor control device according to any one of claims 1 to 4, wherein,

further comprises a basic information acquiring unit for acquiring an initial position and an initial reaction force of the driven body, and an arrival position and an arrival reaction force,

the position command creating unit creates the position command for changing the target position with time so as to have a first position change time at which a first order differential value of the target position is fixed and a first order differential value of the target position is fixed, a second position change time after the first position change time and a third position change time after the second position change time at which a second order differential value of the target position is opposite in sign to a second order differential value of the first position change time and a last target position is equal to the arrival position,

the reaction force command generating unit generates the reaction force command for changing the target reaction force with time so as to have a first reaction force change time, a second reaction force change time after the first reaction force change time, and a third reaction force change time after the second reaction force change time, wherein the first reaction force is set to a value equal to the initial reaction force and a second differential value of the target reaction force is fixed in the first reaction force change time, the first differential value of the target reaction force is fixed in the second reaction force change time, the second reaction force change time is substantially equal in length to the second position change time, and the second differential value of the target reaction force is set to a value opposite in sign to the second differential value of the first reaction force change time in the third reaction force change time, and setting the last target reaction force to a value equal to the arrival reaction force.

6. The servomotor control device according to claim 5, wherein,

the reaction force command creating unit sets the first reaction force change time or the second reaction force change time to a time specified by a program.

Technical Field

The present invention relates to a servo motor control device.

Background

For example, it is sometimes desirable to accurately control the position and pressure (reaction force to which a driven body receives) of the driven body such as a die (japanese: ダイ) during press working at each time. For example, a slight difference in conditions such as a deviation of the workpiece may cause a large change in the pressure applied to the driven body. Therefore, the following technique is proposed: the driven body is driven by a servo motor capable of performing detailed feedback control, and the position and force of the driven body are controlled.

As an example, patent document 1 describes "a servo motor control device including: a force detection unit that detects a force received from the outside by a driven body driven by the servo motor; a position command generation unit that generates a position command for indicating a position of the driven body; a position detection unit that detects a position of the driven body; a force command generation unit that generates a force command indicating a force to which the driven body should be subjected; a position control processing unit that generates a motor operation command based on a position deviation obtained from the position command generated by the position command generating unit and the position detected by the position detecting unit; a force control processing unit that generates a motor operation command based on a force deviation obtained from the force command generated by the force command generating unit and the force detected by the force detecting unit; and a control method selection unit that selectively switches between position control for controlling the operation of the servo motor in accordance with the motor operation command of the position control processing unit and force control for controlling the operation of the servo motor in accordance with the motor operation command of the force control processing unit by comparing the motor operation command generated by the position control processing unit with the motor operation command generated by the force control processing unit, wherein when a force is applied to the driven body from the outside, a control device of the servo motor controls the operation of the servo motor so that the driven body receives a predetermined force, and the control device of the servo motor further includes a command correction unit that corrects the force command generated by the force command generation unit or the position generated by the position command generation unit And a command correction unit that corrects the command and transmits the corrected command to the force control processing unit or the position control processing unit to change the timing at which the control method selection unit switches between the position control and the force control.

Patent document 1: japanese laid-open patent publication No. 2006-130533

Disclosure of Invention

Problems to be solved by the invention

The control device described in patent document 1 controls the force to be a desired value in a state where the force is applied to the driven body from the outside, controls the position to be a desired value in a state where the force is not applied to the driven body from the outside, and does not control the position of the driven body in a state where the force is applied to the driven body from the outside. Specifically, in the technique described in patent document 1, the force of the driven body is driven so as to match the command value, and thus the moving speed of the driven body may become excessively high. In particular, when the speed is controlled to be over-ridden (override) in order to improve the machining efficiency, there is a high risk that the position or force of the driven body may deviate from an appropriate value.

Therefore, a servomotor control device capable of accurately controlling the position of the driven body and the reaction force applied to the driven body is desired.

Means for solving the problems

A servo motor control device according to an aspect of the present disclosure includes: a position command generating unit that generates a position command for specifying a target position to be located at by time a driven body driven by a servo motor; a reaction force command generating unit that generates a reaction force command for specifying a target reaction force to be applied to the driven body by driving the servo motor, for each period of time; a position acquisition unit that acquires an actual position of the driven body; a position reference drive control unit that generates a position reference drive signal for driving the servo motor so that the position acquired by the position acquisition unit approaches the target position; a reaction force acquisition unit that acquires a reaction force actually received by the driven body; a reaction force reference drive control unit that generates a reaction force reference drive signal for driving the servo motor so that the reaction force acquired by the reaction force acquisition unit approaches the target reaction force; and a drive signal selection unit that selects either one of the position reference drive signal and the reaction force reference drive signal, wherein the position command generation unit generates the position command such that the target position is in a relationship of two or more times with respect to time, and the reaction force command generation unit generates the reaction force command such that a relationship between the target reaction force and the target position is substantially linear.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present disclosure, it is possible to provide a servomotor control device capable of accurately controlling the position of a driven body and a reaction force applied to the driven body.

Drawings

Fig. 1 is a block diagram showing a configuration of a machine tool including a servo motor control device according to an embodiment of the present disclosure.

Fig. 2 is a diagram showing a position command and a reaction force command generated in the servo motor control device of fig. 1.

Fig. 3 is a block diagram showing control of a position command and a reaction force command in the servo motor control device of fig. 1.

Fig. 4 is a diagram showing an alternative of the position command and the reaction force command generated in the servo motor control device of fig. 1.

Fig. 5 is a flowchart showing a control procedure in the servomotor control device of fig. 1.

Description of the reference numerals

1: a servo motor control device; 10: a basic information acquisition unit; 20: a position command making unit; 30: a reaction force command generating unit; 40: a position acquisition unit; 50: a position reference drive control unit; 60: a reaction force acquisition unit; 70: a reaction reference drive control unit; 80: a drive signal selection section; m: a servo motor; w: a driven body.

Detailed Description

Embodiments of the present disclosure are described below with reference to the drawings. Fig. 1 is a block diagram illustrating a configuration of a machine tool 100 including a configuration of a servo motor control device 1 according to an embodiment of the present disclosure.

The machine tool 100 shown in fig. 1 includes a driven body (e.g., a press type) W, a servo motor M for driving the driven body W, a servo driver S for supplying a driving current to the servo motor M, and a servo motor control device 1 for inputting an operation command to the servo driver S, and includes a position detection unit P for detecting a position of the driven body W as a rotational position of the servo motor M, and a reaction force detection unit F for detecting a reaction force received by the driven body W from the outside.

The servomotor control device 1 includes: a basic information acquiring unit 10 that acquires an initial position and an initial reaction force and an arrival position and an arrival reaction force of a driven body W driven by a servo motor M; a position command generating unit 20 that generates a position command for specifying a target position to be located by the driven body W for each time; a reaction force command generating unit 30 that generates a reaction force command for specifying a target reaction force to be applied to the driven body W by driving the servo motor M in time; a position acquisition unit 40 that acquires an actual position of the driven body W; a position reference drive control unit 50 that generates a position reference drive signal for driving the servo motor M so that the position acquired by the position acquisition unit 40 approaches the target position; a reaction force acquisition unit 60 that acquires a reaction force actually received by the driven body W; a reaction force reference drive control unit 70 that generates a reaction force reference drive signal for driving the servo motor M so that the reaction force acquired by the reaction force acquisition unit 60 approaches a target reaction force; and a drive signal selection unit 80 that selects either one of the position reference drive signal and the reaction force reference drive signal.

The servo motor control device 1 can be configured by installing an appropriate program in a computer device having a CPU, a memory, and the like. The basic information acquisition unit 10, the position command generation unit 20, the reaction force command generation unit 30, the position acquisition unit 40, the position reference drive control unit 50, the reaction force acquisition unit 60, the reaction force reference drive control unit 70, and the drive signal selection unit 80 of the servo motor control device 1 are functionally distinct, and may not be clearly distinguished in physical structure and program structure.

The basic information acquiring unit 10 can be configured as follows, for example: the machining program is analyzed to obtain an initial position and an initial reaction force (a position and a reaction force of an arrival position and an arrival pressure of a previous command) of the driven body W, and an arrival position and an arrival reaction force, among the commands of the machining program.

The position command generating unit 20 generates a position command in which the target position of the driven object W at each time is in a relationship of two or more times with respect to time, based on the initial position and the arrival position of the driven object W acquired by the basic information acquiring unit 10 and parameters specified in the machining program or stored in advance in the servo motor control device 1. That is, the position command creating unit 20 may be configured to calculate the target position x as a time function x (t) a of two or more times_n·tⁿ+A_n-1·t^n-1+···+A₀·t⁰. N is an integer of 2 or more, A_nAre the coefficients of each time.

As a specific example, as shown in fig. 2, the position command generating unit 20 may be configured to generate a time function x (t) a where the target position is quadratic₂·t²+A₁·t+A₀In the form of a time-varying position command. In this case, the position command may include a first position change time Q1, a second position change time Q2 after the first position change time Q1, and a third position change time Q3 after the second position change time Q2, wherein the first target position is set to a value equal to the initial position and the second differential value (acceleration) of the target position is fixed at the first position change time Q1, and the first differential value (velocity) of the target position is fixed (a) at the second position change time Q2₂0), at the third position change time Q3, the second order differential value of the target position is set to a value whose positive and negative are opposite to those of the first position change time Q1, and the last target position is set to a value equal to the arrival position. In fig. 2, the portions indicated by the broken lines indicate the states of holding the command values between the preceding step and the subsequent step.

The values of the second order differential value and the first order differential value of the target position in the position command have appropriate values depending on the device configuration of the machine tool 100, the object to be machined, and the like. Therefore, it is preferable to set these values to values designated in the machining program or values stored in advance in the servomotor control device 1.

The reaction force command generating unit 30 generates a reaction force command so that the relationship between the target reaction force and the target position is substantially linear. As shown in fig. 3, the correlation coefficient between the time at which the target position is reached and the time at which the target reaction force is reached is preferably equal to or greater than the ratio between the gain of the position reference drive control unit 50 and the gain of the reaction force reference drive control unit 70. By setting the correlation coefficient between the position command and the reaction force command to be equal to or greater than the ratio, it is possible to suppress a deviation between the reaction force and the target reaction force when the servo motor M is driven by the position reference drive signal and a deviation between the position and the target position when the servo motor M is driven by the reaction force reference drive signal. This can keep both the press pressure and the press speed in the machine tool 100 within appropriate ranges, thereby improving the machining quality. The lower limit of the specific numerical value of the correlation coefficient between the position command and the reaction force command is preferably 0.90, and more preferably 0.95.

Therefore, like the position command creating unit 20, the reaction force command creating unit 30 creates a reaction force command in which the target reaction force of the driven body W at each time is in a relationship of two or more times with respect to time, based on the initial reaction force and the arrival reaction force of the driven body W acquired by the basic information acquiring unit 10 and parameters specified in the machining program or stored in the servo motor control device 1 in advance. That is, the reaction force command creating unit 30 may be configured to calculate the target reaction force y as a time function y (t) ═ B having the same number of times as the time function x (t) of the target position x_n·tⁿ+B_n-1·t^n-1+···+B₀·t⁰。

As a specific example, as shown in fig. 2, the reaction force command creating unit 30 may be configured to create a time function y (t) of making the target reaction force quadratic, B₂·t²+B₁·t+B₀Form (a) over timeThe reaction force command is converted. In this case, the reaction force command Sy may include a first reaction force change time R1, a second reaction force change time R2 after the first reaction force change time R1, and a third reaction force change time R3 after the second reaction force change time R2, wherein the first reaction force change time R1 is set to a value equal to the initial reaction force, the second differential value (acceleration) of the target reaction force is fixed, and the first differential value (velocity) of the target reaction force is fixed (B2 is set to a value equal to the first differential value (velocity) of the target reaction force₂0), at the third reaction force change time R3, the second order differential value of the target reaction force is set to a value whose positive and negative are opposite to those of the first reaction force change time R1, and the final target reaction force is set to a value equal to the arrival reaction force.

Preferably, the first reaction force change time R1, the second reaction force change time R2, and the third reaction force change time R3 in the reaction force command are substantially equal to the first position change time Q1, the second position change time Q2, and the third position change time Q3 in the position command, and particularly preferably, the second reaction force change time R2 in the reaction force command is substantially equal to the second position change time Q2 in the position command. This enables the relationship between the target reaction force and the target position to be substantially linear.

The lower limit of the ratio of the second reaction force change time R2 to the second position change time Q2 is preferably 0.95, and more preferably 0.98. On the other hand, the upper limit of the ratio of the second reaction force change time R2 to the second position change time Q2 is preferably 1.05, and more preferably 1.02. By setting the ratio of the second reaction force change time R2 to the second position change time Q2 to be equal to or greater than the lower limit and equal to or less than the upper limit, the relationship between the position command and the pressure command can be made substantially linear, and the deviation of the actual position and reaction force from the target position and target reaction force can be suppressed.

As shown in fig. 4, the reaction force command generating unit 30 may generate a reaction force command as follows: the target reaction force in the reaction force command reaches the arrival reaction force and becomes a fixed value before the target position in the position command reaches the arrival position. That is, the reaction force command creating unit 30 may make the first reaction force change time R1 and the third reaction force change time R3 in the reaction force command slightly shorter than the first position change time Q1 and the third position change time Q3 in the position command. Therefore, the reaction force command may have a reaction force holding time R4 for holding the target reaction force to the reaction force after the third reaction force change time R3 so that the entire time length matches the entire time length of the position command.

In order to generate such a reaction force command, the values of the first reaction force change time R1 and the third reaction force change time R3, or the ratios of the first reaction force change time R1 and the third reaction force change time R3 to the first position change time Q1 and the third position change time Q3 may be described in the machining program. In this case, the command of the machining program may include a code number indicating a command to which the present embodiment is applied, an arrival position, a speed in the second reaction force change time R2, and lengths of the arrival reaction force and the first reaction force change time R1.

The reaction force command generating unit 30 may generate the reaction force command by making the second reaction force change time R2 in the reaction force command slightly shorter than the second position change time Q2 in the position command as follows: the target reaction force in the reaction force command reaches the arrival reaction force before the target position in the position command reaches the arrival position, and becomes a fixed value. In this case, the value of the second reaction force change time R2 or the ratio of the second reaction force change time R2 to the second position change time Q2 may be described in the machining program.

The response of the feedback control of the reaction force of the driven body W is slower than the response of the feedback control of the position of the driven body W. Therefore, by making the target reaction force in the reaction force command reach the reaction force before the target position in the position command, and compensating for the delay in response of the reaction force control, the actual position of the driven body W and the actual reaction force can be made more linear, and therefore, the deviation of the actual position and the reaction force from the target position and the target reaction force can be further reduced.

The position acquisition unit 40 acquires the detection value of the position detection unit P. The position detection unit P can be, for example, a rotary encoder provided in the servo motor M.

The position reference drive control unit 50 generates a position reference drive signal for specifying an output of the servo motor M, for example, a speed, a torque, and the like, based on a deviation between the current target position in the position command and the actual position of the driven body W acquired by the position acquisition unit 40. That is, the position reference drive control unit 50 performs feedback control of changing the value of the position reference drive signal so that the position of the driven body W approaches the target position.

The reaction force acquisition unit 60 acquires the detection value of the reaction force detection unit F. The reaction force detection unit F may be configured to include, for example, a strain gauge.

The reaction force reference drive control unit 70 generates a reaction force reference drive signal for specifying the output of the servo motor M, for example, the speed, the torque, and the like, based on the deviation between the current target reaction force in the reaction force command and the actual reaction force of the driven body W acquired by the reaction force acquisition unit 60. That is, the reaction force reference drive control unit 70 performs feedback control in which the value of the reaction force reference drive signal is changed so that the reaction force of the driven body W approaches the target reaction force.

The drive signal selection unit 80 selects either one of the position reference drive signal and the reaction force reference drive signal in consideration of the value of the position reference drive signal and the value of the reaction force reference drive signal, and inputs the selected signal to the servo driver S. Specifically, the drive signal selection unit 80 may be configured to input the smaller one of the values of the position reference drive signal and the reaction force reference drive signal to the servo driver S. The drive signal selection unit 80 may determine which of the position reference drive signal and the reaction force reference drive signal is to be selected, with reference to past values of the position reference drive signal and the reaction force reference drive signal, and other information than the past values.

Fig. 5 shows a control procedure of one step of the machine tool 100 in the servo motor control apparatus 1. The servo motor control device 1 includes the following steps: acquiring basic information including an initial position and an initial reaction force of the driven body W and an arrival position and an arrival reaction force (step S11: basic information acquisition step); generating a position command for specifying a target position of the driven body W by time (step S12: position command generation step); generating a reaction force command for specifying a target reaction force to be applied to the driven body W for each time period (step S13: reaction force command generating step); acquiring an actual position of the driven body W (step S14: position acquisition process); generating a position reference drive signal for driving the servo motor M so that the actual position of the driven body W approaches the target position (step S15: position reference drive signal generation step); acquiring a reaction force actually received by the driven body W (step S16: reaction force detection step); generating a reaction force reference drive signal for driving the servo motor M so that an actual reaction force of the driven body W approaches a target reaction force (step S17: reaction force reference drive signal generation step); comparing the position reference drive signal with the reaction force reference drive signal (step S18: drive signal comparison process); outputting a position reference drive signal to the servo driver S (step S19: position reference drive signal output process); outputting a reaction force reference drive signal to the servo driver S (step S20: reaction force reference drive signal output step); and confirming whether the process to which the control is applied has ended (step S21: end confirmation process).

In the basic information acquisition step of step S11, the basic information acquisition unit 10 acquires the initial position, the initial reaction force, the arrival position, and the arrival reaction force of the driven body W, and information necessary for generating the position command and the reaction force command.

In the position command generating step of step S12, the position command generating unit 20 generates a position command for changing the target position over time based on the information acquired in the basic information acquiring step.

In the reaction force command generating step of step S13, the reaction force command generating unit 30 generates a reaction force command in which the target reaction force is changed with time so that the relationship with the target position is substantially linear, based on the information acquired in the basic information acquiring step.

In the position acquisition step of step S14, the current position of the driven object W is confirmed by the position acquisition unit 40.

In the position reference drive signal generating step of step S15, the position reference drive control unit 50 generates a position reference drive signal for driving the servomotor M so that the deviation between the current target position in the position command created in the position command creating step and the position of the driven body W recognized in the position acquiring step is reduced.

In the reaction force detection step of step S16, the current reaction force acting on the driven body W is confirmed by the reaction force acquisition unit 60.

In the reaction force reference drive signal generating step of step S17, the reaction force reference drive control unit 70 generates a reaction force reference drive signal for driving the servomotor M so that the deviation between the current target reaction force in the reaction force command generated in the reaction force command generating step and the reaction force of the driven body W recognized in the position acquiring step is reduced.

In the drive signal comparison step of step S18, it is checked whether or not the value of the position reference drive signal generated in the position reference drive signal generation step is equal to or less than the value of the reaction force reference drive signal generated in the reaction force reference drive signal generation step. In this drive signal comparison step, when the position reference drive signal is equal to or less than the reaction force reference drive signal, the process proceeds to a position reference drive signal output step of step S19, and when the position reference drive signal exceeds the reaction force reference drive signal, the process proceeds to a reaction force reference drive signal output step of step S20.

In the position reference drive signal output step of step S19, the position reference drive signal generated in the position reference drive signal generation step is output. On the other hand, in the reaction force reference drive signal output step of step S20, the reaction force reference drive signal generated in the reaction force reference drive signal generation step is output. That is, in steps S18 to S20, the smaller one of the position reference drive signal and the reaction force reference drive signal is selected and output to the servo driver S.

In the end checking step of step S21, it is checked whether the step to which the control is applied has ended, that is, whether the end of the time of the position command and the reaction force command has been reached. If the process to which this control is applied is not completed, that is, if there are remaining target positions that are not used in the position reference drive signal generation process and target reaction forces that are not used in the reaction force reference drive signal generation process, the process returns to step S14 and the subsequent processes are repeated.

As described above, the servo motor control device 1 generates the position command having a relationship of two or more times with respect to time in the position command generating unit 20, and generates the reaction force command having a substantially linear relationship with the position command in the reaction force command generating unit 30. Thus, the servomotor control device 1 can suppress an increase in the difference between the actual reaction force acting on the driven body W and the target reaction force in the reaction force command when feedback control is performed to bring the actual position of the driven body W closer to the target position in the position command using the position reference drive control unit 50. In addition, the servomotor control device 1 can suppress an increase in the difference between the actual position of the driven body W and the target position in the position command even when feedback control is performed using the reaction force reference drive control unit 70 to bring the reaction force acting on the driven body W closer to the target reaction force in the reaction force command. This effect is particularly remarkable when performing the override control for increasing the operating speed of the machine tool 100.

Although the embodiments of the servomotor control device according to the present disclosure have been described above, the servomotor control device according to the present disclosure is not limited to the above-described embodiments. The effects described in the present embodiment are merely the best effects obtained by the present disclosure, and the effects obtained by the servomotor control device according to the present disclosure are not limited to the effects described in the present embodiment.

In the servo motor control device according to the present disclosure, the position command and the reaction force command may be calculated as any function such as an exponential function or a trigonometric function, may be calculated by connecting a plurality of linear functions, or may be calculated with reference to any reference waveform.