JP2006085272A - Speed control device and method for controlling position control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed control device capable of enhancing the responsiveness of speed/position control and increasing compensation for disturbance forces and a method for controlling a position control device. <P>SOLUTION: The method for controlling the rotational speed control device having a servo motor, a controller, and a load machine which is a control target 2 includes compensating a loop gain that has been decreased by the coupling of load inertia, by increasing load inertia J<SB>L</SB>to twice the inertia J<SB>M</SB>of the servo motor or more, and by multiplying a rotational speed control gain 2 by (1+J<SB>L</SB>/J<SB>M</SB>) times. This increase in the rotational speed gain 2 does not change the responsiveness of a closed loop but increases the effect of controlling disturbance forces by the rotational speed control gain, that is, (1+J<SB>L</SB>/J<SB>M</SB>), resulting in a 50% or more increase in control accuracy over conventional methods. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation speed control device, a rotation angle control device, a linear speed control device, and a control method for a linear position control device that drive a load machine.

  As an auto tuning method for servo motors, etc., a real-time auto tuning method is generally used in which an error with respect to a command value is detected instantaneously and a correction signal corresponding to the magnitude of the error is given to maintain fidelity. However, control against sudden disturbances is unstable, and particularly in digital control, the load on the CPU is large and the system tends to be complicated. In addition, although initial type auto-tuning that gives acceleration / deceleration signals to estimate load inertia and sets gain parameters has been generalized, the perfect one was not commercialized due to lack of theoretical considerations. . For this reason, it has been common to set many gain parameters with careless manual adjustment that relies on intuition and experience.

In order to easily and reliably adjust the gain parameter for determining the fidelity and stability of the operation with respect to the command in the operation control of the mechanical system by the negative feedback method,
A = Load mass ratio = (Load mass value converted on the motor side) / (Movable value of the linear motor alone),
B = Load inertia moment ratio = (Motor inertia converted load inertia value) / (Motor rotor inertia value)
, The value of the total gain (value at no load: 0 dB) +10 log {1+ (A or B)} [dB],
That is, it has been previously proposed to multiply the gain by the square root of {1+ (A or B)} (see Patent Document 1).
Further, as a condition for maximizing the energy transfer efficiency from the servo motor to the load machine, it has been said that the ratio of the motor inertia and the load inertia is 1: 1 (for example, non-patent). Reference 1).

JP 2001-209403 A (page 1-3, FIG. 1) Yasukawa Electric Manufacturing Co., Ltd. “Introduction to Servo Technology for Mechatronics” published by Nikkan Kogyo Shimbun, October 30, 1985, p. 14-15

However, in the method proposed in Patent Document 1, the conventional rotational speed control method takes the procedure of multiplying the control gain by the square root of {1+ (A or B)} when there is no load, so the control gain is low. There was too much problem.
In addition, when the motor inertia and the load inertia are 1: 1 as described in Non-Patent Document 1, there is a problem that the control gain is too low and the compensation for the disturbance force is not large.
The present invention has been made in view of such problems, and provides a speed control device and a control method for the position control device that can increase the response to speed and position control and increase the compensation for disturbance force. For the purpose.

  In order to solve the above problems, a first configuration of the present invention is a control method of a rotational speed control device including a servo motor for driving a load machine and a controller, wherein the load inertia is at least twice the servo motor inertia. The rotational gain is increased by (1 + load inertia / servo motor inertia) times to compensate for the loop gain reduced by the combination of load inertia.

In the conventional control method, the inertia ratio (servo motor inertia and load inertia) of the servo system has been considered to be optimal from the viewpoint of maximizing energy transmission efficiency (Non-patent Document 1). However, the basic function of the servo system should be considered as a converter from numerical information to position (speed). At this time, the optimum inertia ratio is different from the conventional condition. The control accuracy of the servo system increases as the gain (speed loop) increases. When the control target can be assumed to be a rigid body, the motor inertia J _M and the load inertia J _L are 1 / (J _M + J _L ) with respect to the loop gain of the speed control system. An increase in inertia reduces the loop gain. Therefore, when the speed proportional gain is multiplied by (J _M + J _L ), the loop gain does not change. The increase in the proportional gain does not change the response of the closed loop, but the effect of suppressing the disturbance force is increased by the rotational speed control gain, that is, (1 + load inertia / servo motor inertia), and the control accuracy is improved. Therefore, load inertia / servo motor inertia ≧ 2 in order to improve the disturbance force suppression effect by 50% or more with respect to load inertia / servo motor inertia = 1, which has been conventionally set to the optimum value.

  According to a second configuration of the present invention, in the control method of the rotation angle control device including the servo motor that drives the load machine and the controller, the speed control method of the first configuration is applied to the rotation angle control loop. The rotation angle of the load machine is controlled. Thus, by using the speed control device of the first configuration as the minor loop in the rotation angle control loop, the response of the rotation angle speed control can be improved, and as a result, the response of the rotation angle control can be improved.

  According to a third configuration of the present invention, in the control method of the linear speed control device including a servo motor, a controller, a ball screw coupled to the servo motor, and a load machine driven by the ball screw, The rotational speed control method of the first configuration is applied to the speed control of the servo motor, and the linear speed of the load machine is controlled. Thus, in the speed control device in which the ball screw is coupled to the servo motor, the linear speed control response can be improved by applying the control method of the speed control device of the first configuration to the linear speed control loop.

  According to a fourth aspect of the present invention, there is provided a linear method for controlling a linear position control apparatus including a servo motor, a controller, a ball screw coupled to the servo motor, and a load machine driven by the ball screw. The control method of the third configuration is applied to the minor loop of the position control loop to control the linear position of the load machine. In this way, by connecting the ball screw to the servo motor and using the speed control device of the third configuration as the minor loop in the linear position control loop, the response of the linear speed control is improved. Response can be improved.

  According to a fifth configuration of the present invention, in a control method of a linear speed control device including a servo motor for driving a load machine and a controller, the linear load mass is set to be twice or more of the servo motor movable part mass, and the linear speed control is performed. The gain is increased by (1 + linear motor movable part mass / load mass) times to compensate for the loop gain reduced by the combination of the load masses. Thus, by making the linear load mass more than twice the mass of the servo motor moving part, it is possible to improve the response of the linear velocity control by compensating for the loop gain reduced by the coupling of the load mass.

  According to a sixth configuration of the present invention, in the control method of the linear position control device including the linear servo motor that drives the load machine and the controller, the control method of the fifth configuration is applied to the linear position control loop. The linear position of the load machine is controlled. Thus, by using the speed control device of the fifth configuration in the linear position control loop using the linear motor, the response of the linear speed control can be improved, and as a result, the response of the linear position control can be improved. it can.

According to the first configuration of the present invention, the rotational speed control performance can be improved, and the compensation for the disturbance force can be increased.
According to the second configuration of the present invention, the position control performance can be improved, and the compensation for the disturbance force can be increased.
According to the third configuration of the present invention, the response of the linear velocity control can be improved, and the compensation for the disturbance force can be increased.
According to the fourth configuration of the present invention, the response of the linear velocity control is improved. As a result, the response of the linear position control can be improved, and the compensation for the disturbance force can be increased.
According to the fifth configuration of the present invention, it is possible to improve the response of the linear velocity control by compensating for the loop gain reduced by the coupling of the load mass, and to increase the compensation for the disturbance force.
According to the sixth configuration of the present invention, the response of the linear velocity control is improved. As a result, the response of the linear position control can be improved, and the compensation for the disturbance force can be increased.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing a configuration of a rotation speed control device according to an embodiment of the present invention. In the figure, 1 is a controlled object, 2 is a rotational angular velocity control gain, 3 is a subtractor, 4 is a subtractor, _Vr is a rotational angular velocity command, V is a rotational angular velocity, _TM is a servo motor generated torque, T is a drive torque, T _d indicates the disturbance torque.
As shown in FIG. 1, the transfer function of the control object 1 is obtained by integrating 1 / (servo motor inertia J _M + load inertia J _L ). The transfer function of the rotational speed control gain 2 is obtained by multiplying K _V by (1 + load inertia J _L / servo motor inertia J _M ), where K _V is the gain of the servo motor alone. And because it is J _L / J _M> 0, the rotational speed control gain is always greater than K _V, moreover rotational speed control gain as the load inertia J _L is greater than the servo motor inertia J _M is larger than K _V, torque The rotational speed control error due to the disturbance _Td can be reduced.

FIG. 2 is a block diagram showing a configuration of a rotation speed control device of a single servo motor when no load is taken into consideration. Control object 5 has a the integral of the first servo motor inertia J _M min, rotational speed control gain 6 has a K _V. The loop gain of the rotational speed control device in FIG. 2 is K _V / J _M. The loop gain of the rotation speed control device of FIG. 1 is also K _V / J _M , and the loop gain is the same as that of the rotation speed control device when no load is taken into consideration.

FIG. 3 shows an experimental apparatus that demonstrates the effects of the present invention. The rotational speed of the DC servo motor 21 is controlled by the digital controller 22, and the DC servo motor 21 is driven via the DC amplifier 23 to feed back the rotational speed signal of the tacho generator. As load inertia, a disk is rigidly coupled to the load side shaft of the DC servo motor 21.
FIG. 4 shows the rotational speed control responses measured for four types of load inertia. The horizontal axis is the rotational speed command, and the vertical axis is the DC motor rotational speed. The experiment was conducted under four conditions, where the load inertia was zero times (a), 1 time (b), 3 times (c), and 7 times (d) of the DC servo motor inertia. Due to the Coulomb friction existing in the bearing of the DC servo motor, an error that causes the rotational speed response to become a dead zone is generated. It can be seen that (a) the DC servo motor alone has the largest error, and the response error decreases as the load inertia increases. One time of (b) is what was conventionally set to the optimum value (Non-Patent Document 1). In order to improve the effect of suppressing disturbance force by 50% or more, load inertia / servo motor It is preferable that inertia ≧ 2. When the connection between the motor and the load can be considered as a rigid body, a large rotational speed control gain can be set as much as possible.However, in reality, some vibration characteristics appear, and the maximum acceleration when the load is combined is In order to decrease to 1 / (1 + J _L / J _M ), it is practical that the inertia ratio is about 4 to 9 times.

FIG. 5 is a diagram showing a time response when the DC servo motor is a single unit, where (a) is a rotation speed command and (b) is a response rotation speed. From the figure, it can be seen that the response rotation speed (b) shows a large dead zone and the amplitude is small.
FIG. 6 shows a case where the load inertia J _L is 7 times the DC servo motor inertia J _M , the rotational speed control gain is 8 times, the response rotational speed (b) is a dead zone, and the decrease in the amplitude is also small. I understand that. Thereby, the effect of the present invention was proved.

  In this way, the load inertia is set to be twice or more larger than the servo motor inertia and the rotation angular velocity control gain is set to (1 + servo motor inertia / load inertia). Thus, the rotation angle control performance can be improved by 50% or more of the inertia ratio.

  A second embodiment of the present invention will be described with reference to FIG. In this embodiment, the rotation angle θ of the servo motor is controlled with respect to the rotation angle command θr, and a block 10 represents the speed control device represented by the transfer function of FIG. Reference numeral 11 is a rotation angle proportional gain, and 12 is an integrator (not actually present, but shown as a physical phenomenon) from a rotation speed to a rotation angle. Thus, by using the speed control device of the first embodiment as a minor loop in the rotation angle control loop, the response of the rotation angle speed control is improved, and as a result, the response of the rotation angle control can be improved.

A third embodiment of the present invention will be described with reference to FIGS. The present embodiment is a linear speed control device in which a ball screw is coupled to a servo motor and driven so that the speed V _L of the load machine becomes a speed command Vr by the ball screw. In FIG. 8, 5 is a control target, 6 is a rotational speed control gain, 7 is a rotation / linear conversion block for converting rotational motion into linear motion by a ball screw having a pitch p, and 8 is a mass of a movable part coupled to the ball screw. A differentiator with _ML as a coefficient, 9 is a linear / rotational conversion block for converting linear motion into rotational motion. FIG. 9 shows an equivalent block diagram of the control system shown in FIG. 8, and it can be seen that it has the same shape as the block diagram of FIG. In FIG. 9, is set to _{J L = (p / 2π)} 2 M L.
As described above, in the speed control apparatus in which the ball screw is coupled to the servo motor, the linear speed control response can be improved by applying the control method of the speed control apparatus of the first embodiment to the linear speed control loop.

A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, the linear position X of the ball screw coupled to the servo motor is controlled in response to the linear position command Xr. Is shown. 14 is a linear position proportional gain, and 15 is an integrator (not actually present, but shown as a physical phenomenon) from a linear velocity to a linear position.
In this way, by connecting the ball screw to the servo motor and using the speed control device of the third embodiment as a minor loop in the linear position control loop, the response of the linear speed control is improved. As a result, the response of the linear position control is improved. Can be improved.

A fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, in a linear speed control device including a servo motor, a controller, and a load machine, the linear load mass is set to at least twice the mass of the servo motor movable part, and the linear speed control gain is (1 + linear motor movable part). By increasing the mass / load mass), the loop gain lowered by the coupling of the load masses is compensated.
In FIG. 11, 16 is a control target, 17 is a linear velocity control gain, 3 is a subtractor, 4 is a subtractor, _Vr is a linear velocity command, V is a linear velocity, M _M is a linear motor mover mass, and M _L is The load mass of the movable table or the like, _Td , indicates a disturbance.

As shown in FIG. 11, the transfer function of the controlled object 16 is obtained by integrating 1 / (linear motor mover mass M _M + load mass M _L ). The transfer function of the linear speed control gain 17 is obtained by multiplying K _V by (1 + load mass M _L / linear motor mover mass M _M ), where K _V is the gain of the linear motor alone. And because it is M _L / M _M> 0, the linear speed control gain is always greater than K _V, moreover linear speed control gain as the load weight M _L is greater than the linear motor mover mass M _M is larger than K _V The linear velocity control error due to the disturbance _Td can be reduced.
Similarly to Example 1 for rotational speed control, if load mass / linear motor mover mass ≧ 2, the effect of suppressing disturbance force can be improved by 50% or more.
In this way, in linear speed control using a linear motor, the linear load mass is made more than twice the mass of the moving part of the servo motor to compensate for the loop gain that is reduced due to the coupling of the load mass. Can be improved.

A sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the linear position X of the linear motor is controlled with respect to the linear position command Xr, and a block 18 represents a speed control device represented by the transfer function of FIG. 14 is a linear position proportional gain, and 15 is an integrator (not actually present, but shown as a physical phenomenon) from a linear velocity to a linear position.
Thus, by using the speed control device of the fifth embodiment in the linear position control loop using the linear motor, the response of the linear speed control is improved, and as a result, the response of the linear position control can be improved. .

  In the present invention, the rotational speed control performance can be improved in all control systems as the control amount, the rotational angular speed, the rotational angle, the linear speed or linear position when the ball screw is coupled, the linear speed or linear position by the linear motor, It can be applied to speed control and position control of industrial robots and machine tools.

It is a block diagram which shows the structure of the rotational angular velocity control apparatus which concerns on Example 1 of this invention. It is a block diagram which shows the structure of the rotational angular velocity control apparatus of a servomotor single-piece | unit. It is a block diagram of the system used in order to verify the effect of Example 1 of this invention. It is a figure which shows the experimental result when the response of rotational speed control is measured with respect to four types of load inertia. It is a figure which shows the time response of the rotation angular velocity in the case of a DC servomotor single-piece | unit. It is a figure which shows the time response of rotation angular velocity when making load inertia 7 times the DC servo motor inertia. It is a block diagram which shows the structure of the rotation angle control apparatus which concerns on Example 2 of this invention. It is a block diagram which shows the structure of the linear velocity control apparatus which concerns on Example 3 of this invention. FIG. 9 is an equivalent block diagram of the control system shown in FIG. 8. It is a block diagram which shows the structure of the linear position control apparatus which concerns on Example 4 of this invention. It is a block diagram which shows the structure of the linear speed control apparatus of the linear motor which concerns on Example 5 of this invention. It is a block diagram which shows the structure of the linear position control apparatus of the linear motor which concerns on Example 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control object 2 Rotational angular velocity control gain 3, 4 Subtractor 5 Control object 6 Rotational speed control gain 7 Rotation / linear conversion block 8 Differentiator 9 Linear / rotation conversion block 10 Speed control apparatus 11 represented by the transfer function of FIG. Rotational angle proportional gain 12 Integrator 13 Speed control device expressed by transfer function of FIG. 8 14 Linear position proportional gain 15 Integrator 16 Control target 17 Linear speed control gain 18 Speed control device expressed by transfer function of FIG. DC servo motor 22 Digital controller 23 DC amplifier

Claims (6)

In a control method of a rotation speed control device including a servo motor that drives a load machine and a controller,
Make the load inertia more than twice the inertia of the servo motor,
By increasing the rotational speed control gain by (1 + load inertia / servo motor inertia) times,
A control method for a rotational speed control apparatus, comprising compensating for a loop gain reduced by coupling load inertia. In a control method of a rotation angle control device including a servo motor that drives a load machine and a controller,
A control method for a rotation angle control device, wherein the rotation angle control loop is applied to the rotation angle control loop to control the rotation angle of the load machine. In a control method of a linear speed control device comprising a servo motor, a controller, a ball screw coupled to the servo motor, and a load machine driven by the ball screw,
A control method of a linear speed control device, wherein the rotational speed control method according to claim 1 is applied to speed control of the servo motor to control a linear speed of the load machine. In a control method of a linear position control device comprising a servo motor, a controller, a ball screw coupled to the servo motor, and a load machine driven by the ball screw,
A control method for a linear position control apparatus, wherein the control method according to claim 3 is applied to a minor loop of a linear position control loop to control a linear position of the load machine. In a control method of a linear speed control device including a servo motor that drives a load machine and a controller,
Make the linear load mass more than twice the mass of the moving part of the servo motor.
By increasing the linear speed control gain by (1 + linear motor moving part mass / load mass) times,
A control method for a linear velocity control device, wherein a loop gain reduced due to coupling of load masses is compensated. In a control method of a linear position control device including a linear servo motor that drives a load machine and a controller,
A control method for a linear position control device, wherein the control method according to claim 5 is applied to a linear position control loop to control the linear position of the load machine.

Images