JP2009032008A - Linear actuator - Google Patents

Abstract

A linear actuator capable of generating speed information and increasing a control band without depending on a difference value of position information and a sampling time is realized.
A position control means for calculating a deviation between a position detection value of a slider having a surface motor and a position command value and outputting a speed command value; and a deviation between the speed detection value of the slider and the speed command value. In a linear actuator comprising a speed control means for calculating and outputting a thrust command to the surface motor,
A state estimator for estimating and calculating the speed detection value based on the position detection value and the thrust command is provided.
[Selection] Figure 1

Description

  The present invention provides position control means for calculating a deviation between a position detection value of a slider having a surface motor and a position command value and outputting a speed command value; and a deviation between the speed detection value of the slider and the speed command value. The present invention relates to a linear actuator comprising speed control means for calculating and outputting a thrust command to the surface motor.

  In a linear actuator in which the stators of a pair of linear motors are arranged in parallel at a predetermined distance and the sliders of these linear motors are coupled by arm members, the midpoint position of the arm members is controlled to the command position, and the arm Japanese Patent Application Laid-Open No. 2004-133867 discloses a linear actuator including a posture control unit that suppresses yawing of a member.

  FIG. 5 is a functional block diagram showing a configuration of a conventional linear actuator disclosed in Patent Document 1. As shown in FIG. The first linear motor 10 and the second linear motor 20 are arranged in parallel at a predetermined distance.

A slider 12 incorporating a surface motor is moved along a stator 11 disposed on the first linear motor 10 to be position-controlled. The slider 12, the position detecting means 13 for outputting a position detection signal X _M read the scale which is disposed along the stator 11 (not shown) is mounted.

  Similarly, a slider 22 incorporating a surface motor moves along a stator 21 disposed on the second linear motor 20 to control the position. Position detecting means 23 for reading a scale (not shown) arranged along the stator 21 and outputting a position detection signal Xs is mounted on the slider 22.

  The slider 12 of the first linear motor 10 and the slider 22 of the second linear motor 20 are coupled in a bridge shape by an arm member 30, and the slider 12, the slider 22, and the arm member 30 move together, and the arm member 30. Is controlled as a virtual midpoint position Xc.

The position command Ps from the host device 40 is input to the midpoint position control means 51 of the midpoint position control unit 50. Position detection signal X _M and the position detection signal Xs is inputted into the middle point position detecting means 52, the middle point position signal Xc Based on these sums is calculated.

  The midpoint position control means 51 outputs a speed command Vs obtained by calculating a deviation between the position command Ps and the midpoint position signal Xc to the midpoint speed control means 53. The midpoint speed control means 53 outputs a thrust command Fc obtained by calculating the deviation between the speed signal Vc of the speed detection means 54 that calculates the speed based on the rate of change of the midpoint position signal Xc and the speed command Vs.

  The thrust command Fc is added to a corrected thrust command Fe from an attitude control unit 90 described later via an adder 61 and input to the first driver 70. Similarly, the thrust command Fc is subtracted from the corrected thrust command Fe from the attitude control unit 90 via the subtractor 62 and input to the second driver 80.

  The first driver 70 outputs a drive current Im based on the corrected thrust command (Fc + Fe) to a surface motor (not shown) included in the slider 12 of the first linear motor 10. Similarly, the second driver 80 outputs a drive current Is based on the corrected thrust command (Fc-Fe) to a surface motor (not shown) included in the slider 22 of the second linear motor 20.

When the arm member 30 is positioned, the slider 12 of the first linear actuator and the slider 22 of the second linear actuator generate a positional deviation (yaw angle error, squareness error) with respect to the traveling direction. The generation factor is the following mechanical characteristics.
-Stage level-Parallelism of linear motor-Torsion of arm member-Dynamic delay of control target (because the target of attitude control is a secondary delay system)
・ Friction, disturbance, etc.

Posture control unit 90 has a function of suppressing the yawing angle of the arm member 30 by the position deviation of X _M and Xs. The thrust command Fc to the first driver 70 and the second driver 80 is differentially manipulated by the corrected thrust command Fe output from the attitude control unit 90, and the position of the slider 12 of the first linear actuator is moved in the direction of arrow P. Then, the yaw angle is suppressed by operating the position of the slider 22 of the second linear actuator in the opposite arrow P ′ direction.

The posture target value θs is set to, for example, θs = 0 in order to set the yawing angle to an ideal 0 degree, and is input to the posture control means 91 of the posture control unit 90. Position detection signal X _M and the position detection signal Xs is inputted to the posture detecting means 92 calculates the attitude signal θ representing the output angle based on these differences.

  The attitude control means 91 outputs a speed command Vs ′ obtained by calculating the deviation between the attitude target value θs (= 0 or a constant) and the attitude signal θ to the speed control means 93. The speed control means 93 outputs a corrected thrust command Fe obtained by calculating the deviation between the output θ ′ of the angular speed detection means 94 that calculates the angular speed based on the rate of change of the output angle θ and the speed command Vs ′.

  FIG. 6 is a functional block diagram showing a conventional speed control system that is executed by digital processing in the midpoint position control unit 50 and the attitude control unit 90. The deviation Verr between the speed command Vcmd and the speed feedback value Vfb gives the thrust command f to the controlled object (mass m) via the speed control proportional gain Kv. In the feedback circuit, the speed Vo to be controlled is digitally processed to generate a speed feedback value Vfb.

JP 2006-101570 A "Introduction to Modern Control Theory" by Masatake Shiraishi, Nikkan Kogyo Shimbun, June 10, 1997, first edition, 4th edition issued

  In the conventional speed control system, the speed Vo to be controlled is calculated from the difference value (difference between the current position and the position one sample before) of the position information of the position detectors 13 and 23 constituted by a real-time encoder and the sample time. Yes.

When the velocity resolution ΔV is calculated from the position resolution (difference value) ΔX and the sample time ΔT, the following equation is obtained.
ΔV = ΔX / ΔT

In order to increase the speed resolution ΔV in order to increase the control band of speed control,
(A) The position resolution ΔX is reduced (b) The sampling time ΔT is increased.

  The position resolution ΔX is limited due to the structure of the encoder. Therefore, when the sample time ΔT is set to be long, it becomes impossible to cope with the rapid speed change of the controlled object, and the reliability of the speed control is lowered, so there is a limitation.

  Accordingly, the conventional speed calculation method based on the difference value of the position information and the sample time has a problem that it is difficult to increase the control bandwidth because the speed resolution cannot be increased without reducing the reliability of the speed control. .

  The present invention has been made to solve the above-described problems, and realizes a linear actuator that can generate velocity information and increase a control band without depending on a difference value of position information and a sampling time. It is an object.

In order to achieve such a subject, the present invention has the following configuration.
(1) Position control means for calculating a deviation between a position detection value of a slider having a surface motor and a position command value and outputting a speed command value; and calculating a deviation between the speed detection value of the slider and the speed command value In a linear actuator comprising speed control means for outputting a thrust command to the surface motor,
A linear actuator comprising: a state estimator for estimating and calculating the speed detection value based on the position detection value and the thrust command.

(2) When the position estimator is x (t), the thrust command is f (t), the mass of the slider is m, the viscosity coefficient is d, the restoration coefficient is k, and the constant is A , Equation of motion of the slider,
m · d ² x (t) / dt ² + d · dx (t) / dt + k · x (t) = A · f (t)
The linear actuator according to (1), wherein the speed detection value dx (t) / dt is estimated based on

(3) The sliders of a pair of linear motors arranged in parallel at a predetermined distance are coupled by an arm member, and the position control means and the speed control means for outputting the thrust command are used to determine the midpoint of the arm member. The linear actuator according to (1) or (2), wherein position control and speed control are executed.

(4) Attitude control means for calculating a deviation between a detected value of the yawing angle of the arm member and a target value of the yawing angle and outputting an angular velocity command value; and a deviation between the detected angular velocity value of the arm member and the angular velocity command value The linear actuator according to (3), further comprising a speed control unit that calculates the thrust command and outputs the thrust command.

(5) The linear actuator according to (4), further comprising a state estimator that estimates and calculates a detected value of an angular velocity of the yawing angle based on a detected value of the yawing angle of the arm member and the thrust command. .

(6) The state estimator uses the detected value of the yawing angle as θ (t), the thrust command as f (t), the inertia moment of the arm member as J, the viscosity coefficient as D, the restoration coefficient as K, and the constant as When A
J · d ² θ (t) / dt ² + D · θ (t) / dt + K · θ (t) = A · f (t)
The linear actuator according to (5), wherein the detected angular velocity value dθ (t) / dt is calculated based on

According to the present invention, the following effects can be expected.
(1) By speed estimation calculation by the state estimator, speed information of a continuous and smooth waveform can be obtained in real time with respect to discrete speed information by the conventional method, and controllability of speed control can be improved. it can.

(2) Since speed information can be generated in real time without depending on the difference value of the position information and the sampling time by speed estimation calculation by the state estimator, speed control that increases the control band and suppresses overshoot at high speed is possible. Can be realized.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing a speed control system to which the present invention is applied, and shows a speed control system for a slider of a linear motor having a single configuration. The same elements as those in the conventional speed control system described with reference to FIG.

  A state estimator 100 provided in the feedback circuit receives a thrust command f to be controlled and a current position x1, and outputs a real-time estimated speed x2 (with a hat). The state estimator is a well-known technique in the control field, and Non-Patent Document 1 discloses the theory.

  The basic function of the state estimator will be described below using Equations (1) to (3). The equation of motion of the control target (linear motor, midpoint of bridge-structured linear actuator, arm member attitude control system) is x (t): position, f (t): thrust, m: mass, d: viscosity coefficient, k: When used as a restoration coefficient, it is expressed by equation (1).

Equation (1) can also be expressed as the following equation.
m · d ² x (t) / dt ² + d · dx (t) / dt + k · x (t) = A · f (t)

  Here, by defining the position, velocity, and acceleration as in Expression (2), the equation of motion of Expression (1) is expressed by Expression (3).

  A process for estimating speed information from position information and thrust measured based on this general formula will be described with reference to formulas (4) to (14). The speed defined by Expression (2) is represented by the estimated speed x2 (with hat) shown in Expression (4).

  Similarly, the acceleration defined by Expression (2) is expressed as estimated acceleration x2 (with a hat) shown in Expression (5).

  Expression (6) is obtained by multiplying both sides of Expression (4) by a constant c.

  The difference between Expression (5) and Expression (6) is calculated to obtain Expression (7).

  Here, when the estimated speed x2 (with a hat) is obtained by defining the left side of the equation (7) as z, the equation (8) is obtained.

  Expression (9) is obtained by differentiating Expression (8) and substituting Expression (7).

  The value obtained by moving-(c + d / m) z on the right side of Equation (9) to the left side is set to zero, and this is solved for z to obtain Equation (10).

  The characteristic root λ and the constant c in Expression (10) are obtained by Expression (11). When the characteristic root λ is negative, the speed control system is stable.

  By substituting equation (10) into equation (9), equation (12) is obtained.

  To summarize the above, the differential value of z and the estimated speed x2 (with a hat) are expressed by Expression (13) and Expression (14).

  The functional blocks constituting the state estimator 100 shown in FIG. 1 are expressions (13) and (14) expressed as functional blocks. With such a functional block configuration, the estimated speed x2 (with a hat) can be obtained without complicated calculations for mathematically solving the differential equation.

  The functional blocks constituting the state estimator 100 shown in FIG. 1 represent a general-purpose state estimator. FIG. 2 is a functional block diagram when the state estimator of the present invention is applied to a midpoint control system of a linear motor having a bridge configuration. This state estimator 200 is obtained as k = 0 and A = 1 in the general-purpose state estimator 100.

  FIG. 3 is a functional block diagram when the state estimator of the present invention is applied to an attitude control system of an arm member in a bridge-structured linear motor. This state estimator 300 is obtained as m = J (moment of inertia), d = D, k = K, and A = L / 2 (L: length of arm member) in the general state estimator 100.

Since the input of the attitude control is the angle θ, the motion equation handled by the state estimator 300 is that the detected value of the yawing angle is θ (t), the thrust command is f (t), the inertia moment of the arm member is J, the viscosity coefficient Is D, the restoration coefficient is K, and the constant is A,
J · d ² θ (t) / dt ² + D · θ (t) / dt + K · θ (t) = A · f (t)
The speed detection value dθ (t) / dt is estimated and calculated.

  FIG. 4 is a functional block diagram showing an embodiment of a linear actuator provided with a speed control system including a state estimator to which the present invention is applied, in the midpoint position control unit 50 and the attitude control unit 90. The same elements as those of the conventional configuration described with reference to FIG.

  The state estimator 200 in the midpoint position control unit 50 and the state estimator 300 in the attitude control unit 90 are characteristic portions of the embodiment of the present invention in which the control characteristics of the speed control system are improved compared to the conventional configuration.

It is a functional block diagram which shows the speed control system to which this invention is applied. It is a functional block diagram at the time of applying the state estimator of this invention to the midpoint control system of the linear motor of a bridge | bridging structure. It is a functional block diagram at the time of applying the state estimator of this invention to the attitude | position control system of the arm member in the linear motor of bridge | bridging structure. It is a functional block diagram showing one embodiment of a linear actuator provided with a speed control system to which the present invention is applied. It is a functional block diagram which shows the structure of the conventional linear actuator currently disclosed by patent document 1. FIG. It is a functional block diagram which shows the conventional speed control system currently performed by the digital process in a midpoint position control part and an attitude | position control part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st linear motor 20 2nd linear motor 11,21 Stator 12,22 Slider 13,23 Position detection means 30 Arm member 40 High-order apparatus 50 Midpoint position control part 51 Midpoint position control means 52 Midpoint position detection means 53 Middle Point speed control means 200 State estimator 61 Adder 62 Subtractor 70 First driver 80 Second driver 90 Attitude control section 91 Attitude control means 92 Attitude detection means 93 Speed control means 300 State estimator

Claims (6)

Position control means for calculating a deviation between a position detection value of a slider having a surface motor and a position command value and outputting a speed command value; and calculating a deviation between the speed detection value of the slider and the speed command value In a linear actuator comprising a speed control means for outputting a thrust command to a surface motor,
A linear actuator comprising: a state estimator for estimating and calculating the speed detection value based on the position detection value and the thrust command. When the position estimator is x (t), the thrust command is f (t), the mass of the slider is m, the viscosity coefficient is d, the restoration coefficient is k, and the constant is A, the slider Equation of motion,
m · d ² x (t) / dt ² + d · dx (t) / dt + k · x (t) = A · f (t)
The linear actuator according to claim 1, wherein the speed detection value dx (t) / dt is estimated based on the calculation.   The sliders of a pair of linear motors arranged in parallel at a predetermined distance are coupled by arm members, and the position control means and the speed control means for outputting the thrust command are used to control the position of the middle point of the arm members. The linear actuator according to claim 1, wherein speed control is executed.   Attitude control means for calculating a deviation between a detected value of the yawing angle of the arm member and a target yawing angle value and outputting an angular velocity command value; and calculating a deviation between the detected angular velocity value of the arm member and the angular velocity command value. The linear actuator according to claim 3, further comprising speed control means for outputting the thrust command.   The linear actuator according to claim 4, further comprising a state estimator that estimates and calculates an angular velocity detection value of the yawing angle based on a detection value of the yawing angle of the arm member and the thrust command. The state estimator sets the detected value of the yawing angle as θ (t), the thrust command as f (t), the inertia moment of the arm member as J, the viscosity coefficient as D, the restoration coefficient as K, and the constant as A. When
J · d ² θ (t) / dt ² + D · θ (t) / dt + K · θ (t) = A · f (t)
The linear actuator according to claim 5, wherein the angular velocity detection value dθ (t) / dt is estimated based on the calculation.

Images