JPH11265202A - Control method and controller therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high speed servo controller capable of performing a high speed and high performance control beyond control performance by 2 degree of freedom PID control. SOLUTION: The controller calculates control deviation by subtracting an actual control result yk from a target instruction rk by a subtractor 12, and operates a following control arithmetic operation to the control deflection by a feedback(FB) control arithmetic part 16. A feed/forward(FF) control.arithmetic part 14 operates the control arithmetic operation of fbk =(K2 +K3 Z<-1> +K4 Z<-2> )(rk -yk )/(1-Z<-1> )(1-K1 Z<-1> ), ffk =(K5 +K6 Z<-1> )rk /(1-K1 Z<-1> ), and uk =fbk +ffk based on the target instruction. The feedback arithmetic result fbk of an FB control arithmetic part 16 is added to the feedforward arithmetic result ffk of an FF control arithmetic part 14 by an adding circuit 18, and a motor 1 is driven. In this formula, K1 -KN is a gain, rk is a target instruction in a sampling cycle (k), yk is an actual value, fbk is a feedback arithmetic result, ffk is a feedforward arithmetic result, and uk is a control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and a control apparatus, and more particularly, to a servo control of a device having a drive system requiring high-speed positioning, such as an industrial robot or a component mounting machine for an electric circuit board. The present invention relates to a control method and an apparatus for performing the control. The present invention also relates to a method for automatically determining the control parameters used for the control method and the control device or for determining an optimal control parameter.

[0002]

2. Description of the Related Art PID control for controlling a controlled object by combining control of a proportional (P) operation, an integral (I) operation and a differential (D) operation is widely known. JP-A-8-1714
No. 02 discloses a control device to which such PID control is applied. In the control device disclosed in JP-A-8-171402, a control device that controls a control target such as an arm of an industrial robot using a motor as an actuator is based on sampling control based on a sampling control theory. Control is performed by combining feedforward control with respect to the target command and feedback control with respect to the deviation between the target command and the actual detection signal. PID control parameters are used for the feedback control and the feedforward control. The feedback control calculation formula and the feedforward control calculation formulas 1 and 2 are shown.

[0003]

(Equation 10)

[0004]

[Equation 11]

Japanese Patent Application Laid-Open No. 8-171402 discloses an adjustment of control parameters such as a proportional gain k _p , an integral gain k _i , a differential gain k _d , a zero-order feed forward gain α, and a primary (speed) feed forward gain β. For ease, the disclosure discloses that a control parameter is calculated by variable conversion from poles and zeros of a transfer function of a control system using a variable conversion unit, a variable setting unit, or an optimum pole arrangement calculation unit. More specifically, control parameters are calculated according to the command values a, b, c, f, and g of poles and zeros in the z coordinate system. The calculated control parameters are set in the feedback control operation unit and the feedforward control operation unit and used for actual control.

In the control device described in Japanese Patent Application Laid-Open No. 8-171402, a proportional gain k _p , an integral gain k _i , a differential gain k _d , a zero-order feed forward gain α, and a first order (speed) feed forward gain β If the control parameters are set appropriately, the control target can be controlled well by the effects of the proportional action, the differential action, and the integral action, and the optimum pole arrangement calculation for determining the control parameters can be performed without trial and error. An optimal control parameter can be obtained.

[0007]

Problems to be Solved by the Invention
In the control device disclosed in Japanese Patent Application Laid-Open No. H08-209, although setting of control parameters is easy, the control function itself is not different from that of the conventional two-degree-of-freedom PID control device.
The control performance realized by the control device described in Japanese Patent No. 171402 is equal to that of the two-degree-of-freedom PID control device. That is, the control realized by the calculated control parameters is the optimal operation control in the conventional two-degree-of-freedom PID controller including the PID controller, and higher-speed operation control cannot be realized. High-speed operation is a universal requirement for the control target and the drive system, and higher-speed operation is always required. Therefore, improvement of the control algorithm and provision of a control device that enables such control are demanded. Have been.

In Japanese Patent Application Laid-Open No. Hei 8-171402, only three control parameters, a proportional gain k _p , an integral gain k _i , and a differential gain k _d , are used to determine the five poles related to the feedforward control operation and the feedback control operation. Of these, four poles that substantially affect the response are arranged. However, since there are three control parameters, the number of poles that can be freely arranged is three, and it is not possible to specify where one of the above four poles is arranged. Therefore, the degree of freedom in control parameter design is small, and the range of control performance is also limited. In order to achieve better control performance, a control method with a greater degree of freedom is required.

[0009] The control performance is greatly affected by the sampling time of the controller, and higher performance and higher speed control can be realized by shortening the sampling time. However, since the sampling time is determined by the calculation speed of the control means for performing the control calculation, the sampling time cannot be infinitely reduced. Therefore, from a practical point of view, there is also a need for a means for realizing an operation as high as possible under a certain sampling time determined by the calculation speed.

It is an object of the present invention to provide a control method and a control device according to a control algorithm capable of realizing a higher speed operation than a conventional two-degree-of-freedom PID controller in control at a certain sampling time. Another object of the present invention is to automatically calculate control parameters used in the control method and the control device, and to enable calculation of optimal control parameters, so that special knowledge and skill are not required for adjustment. It is an object of the present invention to provide a method and an apparatus for determining control parameters which do not require much time.

[0011]

According to a first aspect of the present invention, a target command r for an object to be controlled or an actuator is provided.
and _k, performs the deviation (r _k -y _k) based on the following equation 1-1 for each sampling period k feedback control calculation of the actual value y _k of the controlled object or actuator, sampled for the target command r _k for each period k based on the following equation 1-2 performs feedforward control operation, the feed forward calculation result by adding said and ff _k feedback calculation result fb _k, the addition result u
_A control method is provided for controlling an object to be controlled by driving an actuator based on _k .

(Equation 12)

The term (1-z ^-1 ) is included in the denominator of the feedback control arithmetic expression defined in Expression 1-1, which guarantees that the feedback control system includes an integral element. As with the PID control law, control resistant to disturbance is realized. The control law of the present invention defined by the above equation is the same as the conventional two-degree-of-freedom PID control law, but the order of the controller is the same, but K ₁ , K ₂ , K
_3, has four control parameters K _4. Therefore, of the five poles of the control system including the control means and the control target of the present invention, all four poles that substantially affect the response can be freely arranged. As a result, the degree of freedom in control parameter design is increased, and the range of achievable control performance can be widened. As a result, a higher-speed, higher-performance control operation can be realized as compared with the conventional two-degree-of-freedom PID control law.

The gains K ₁ , K ₂ , K ₃ , K ₄ used in the feedback control calculation and the other gains K ₅ , K ₆ used in the feed forward control calculation are respectively defined by the following equations.

(Equation 13)

Further, according to a second aspect of the present invention, a control pair
Indicates the actual position or angle of the elephant or actuator
Sampling means for reading a signal at a predetermined cycle, and control
Target command r to target_kAnd read by the sampling means
Actual position or angle signal y_kCalculate the deviation from
Deviation calculating means, and the deviation (r_k
-Y_k) For each sampling period k
Feed for performing feedback control calculation based on -1
Back calculation means, and the target command r_kAbout Sampli
The feedforward is performed for each switching cycle k based on the following equation 3-2.
Feedforward control operation means for performing word control operation
And the feedforward operation result ff _kAnd the fee
Dback operation result fb_kAnd the addition result u_kTo
Controls the control target by driving the actuator based on
A control device having an adding means is provided.

[Equation 14]

According further to the third aspect of the present invention, a target command r _k of the controlled object or actuator, the deviation of the actual value y _k of the controlled object or actuator (r _k -
y _k ) for each sampling period k
Performs feedback control computation based on the following formula 5-2 wherein target command r _k for each sampling period k
In the control device that performs a feedforward control calculation based on the above, adds the feedforward calculation result ff _k and the feedback calculation result fb _k, and drives an actuator based on the addition result u _k to control a control target. A control parameter determination method for determining the gain,

(Equation 15) Calculating the positions of the poles and zeros in the z-coordinate system of the transfer function of the control system such that the control system including the control target and the actuator exhibits the best control performance with respect to a target value and a disturbance; The positions of the poles and zeros of the function are applied to the following equations to obtain the gains K ₁ , K ₂ ,
A control parameter determination method for calculating K ₃ , K ₄ , K ₅ , and K ₆ is provided.

The gains K ₁ , K ₂ , K ₃ , and K ₄ used in the feedback control calculation and the other gains K ₅ and K ₆ used in the feed forward control calculation are respectively calculated by the following equations.

(Equation 16)

The control method and apparatus according to the present invention are:
A pole arrangement calculating means for calculating a position of a pole and a zero point of a transfer function of the control system such that the control system including the control means and the control target shows the best control performance with respect to a target value and a disturbance; The above control parameters K ₁ , K ₂ , K ₃ , K ₄ , K are based on the positions of the poles and zeros of the transfer function.
_5, to calculate the K _6, having a control means for controlling operation based on the calculated control parameters.

The positions of the poles and zeros of the transfer function of the control system such that the control system exhibits the best control performance with respect to the target value and the disturbance are calculated by the optimum pole arrangement calculating means.
Based on the calculated positions of the poles and zeros, the control parameters K ₁ , K ₂ , K ₃ , K ₄ , K ₅ ,
To calculate the K _6. Based on the calculated control parameters, a feedback control operation and a feedforward control operation are performed in accordance with Equations 1-1 and 1-2. As described above, the denominator contains (1
−z ⁻¹ ), it is guaranteed that an integral element is included, and as in the conventional two-degree-of-freedom PID control law, control resistant to disturbance is realized. Further, the control law of the present invention is based on the conventional 2
Although the degree of freedom PID control law and the order of the controller do not change, the feedback control is performed using _four of K ₁ , K ₂ , K ₃ , and K ₄ .
Has two control parameters. Therefore, of the five poles of the control system including the control means and the control target of the present invention, all four poles that substantially affect the response can be freely arranged. As a result, the degree of freedom in control parameter design is increased, and the range of achievable control performance can be widened. As a result, a higher-speed, higher-performance control operation can be realized as compared with the conventional two-degree-of-freedom PID control law.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A servo control method and a servo control device according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a servo control device according to an embodiment of the present invention.
The servo control device illustrated in FIG. 1 includes an encoder 200 that detects a position or an angle of the motor 1 or the control target, and a controller 100 in order to control the motor 1 that drives the control target via the motor driver 2. . Controller 10
Numeral 0 has a control operation unit 10, a D / A converter 20, a sampling circuit 30, a variable conversion unit 40, a variable setting unit 50, and an optimum pole arrangement operation unit 60. The control operation unit 10 includes the subtractor 1
2. It has a feedforward (FF) control operation unit 14, a feedback (FB) control operation unit 16, and an adder 18.

The encoder 200 detects a position or an angle of the motor 1 or a control target driven by the motor 1, for example, an arm of an industrial robot, a transfer unit of a component mounting machine, or the like. Hereinafter, a case where the rotational position of the control target or the rotor of the motor 1 is detected to control these positions or angles will be exemplified.

The subtractor 12 calculates the position by subtracting the actual position signal y _k detected by the encoder 200 from the target position command r _k at the sampling period k deviation signal (r _k -y _k). The feedback (FB) control calculation unit 16 performs a control calculation based on the following equation 3 with respect to the position deviation signal (r _k −y _k ) calculated by the subtractor 12.

[0022]

[Equation 17]

Feedforward (FF) control operation unit 1
4 performs control computation on the basis of the following equation 4 for the target position command r _k at the sampling period k.

[0024]

(Equation 18)

The adder 18 adds the feedback operation result ff _k of the feedback (FB) control operation unit 16 and the feedback operation result fb _k of the feedback (FB) control operation unit 16 and uses the addition result as a control signal u _k as D / A converter 20. The operation in the adder 18 is shown in Expression 5 below.

[0026]

[Equation 19]

The D / A converter 20 converts the digital control signal calculated by the digital calculation in the control calculator 10 into an analog control signal, and applies the analog control signal to the motor driver 2. The motor driver 2 supplies electric power for driving the motor 1 to the motor 1 according to the control signal applied from the D / A converter 20. Thereby, the motor 1 operates according to the control signal and drives the control target. The result is detected by the encoder 200 and the encoder 2
The detection signal of 00 is applied to the subtractor 12 of the control operation unit 10 via the sampling circuit 30 at each sampling cycle. The above operation is repeated every predetermined sampling period.

As is apparent from Equations 3 and 4, the FB control operation section 16 and the FF control operation section 14 in the present embodiment have six gains K ₁ , K ₂ , K ₃ , K ₄ , K ₄ .
_5, performs control computation using a K _6. These gains are set in accordance with the commanded positions of the poles and zeros of the control system transfer function calculated by the optimum pole arrangement calculation unit 60, or at the specified positions of the poles and zeros of the control system transfer function specified directly from the variable setting unit 50. Accordingly, it is calculated in variable conversion section 40 and set in FF control calculation section 14 and FB control calculation section 16.

As described above, the control operation algorithm in the FF control operation unit 14 and the FB control operation unit 16 in the present embodiment is based on the FF control operation unit and the FB control operation unit in the PID control device described in JP-A-8-171402.
It differs from the calculation algorithm of the control calculation unit. In the present embodiment, the P.P.
Since the number of applied gains is one more than that of the ID control device, the number of poles that can be specified increases, and the number of input values in the variable conversion unit 40 also increases according to the PI described in JP-A-8-171402.
From the five of a, b, c, f, and g in the D control device, a, b, c,
d, f, and g.

As illustrated in FIG. 2, the coordinates of the four poles of the control system are a ± bj and c ± dj, and the coordinates of the two zeros are f ± gj. A, B, and P used here are numerical values calculated from the time constant T0, gain K, and sampling interval T of the control object measured in advance.

The operation of the variable converter 40 will be described with reference to FIG. FIG. 3 is a flowchart showing the operation of the variable conversion unit 40.

Step 1: The coordinate values of poles and zeros in the z-coordinate system: a, b, c, c, f, and g are input to the variable conversion unit 40 from the variable setting unit 50 or the optimum pole arrangement calculation unit 60. These values may be calculated in advance and the result may be input from the variable setting unit 50, or may be input after being calculated by the optimum pole arrangement calculation unit 60.

Step 2: The variable converter 40 determines a, b,
Substituting Equations 6 to 9 for c and d, α1, α2, α3, α4
Is calculated.

[0034]

(Equation 20)

Step 3: The variable converter 40 determines α ₁ , α
E is calculated by substituting ₂ , α ₃ , α ₄ , A, B, P, a, and c into Equation 10.

[0036]

(Equation 21)

Steps 4 and 5: The variable converter 40 checks the calculated value of e. If -1 <e <1, the control system is stable; otherwise, the control system is unstable. If the control system becomes unstable, the polar coordinate values a, b, c, and d are changed in step 5.

Step 6: The variable converter 40 determines α ₁ , α
₂ , α ₃ , α ₄ , A, B, P, K, a, c, e
It is substituted into to Formula 14, to calculate the gain _{K 1, K 2, K 3} , K 4.

[0039]

(Equation 22)

Step 7: The variable conversion unit 40 determines K ₁ , K
Substituting ₂ , K ₃ , K ₄ , f, and g into Equations 15 and 16,
Calculating the gain K _5, K _6.

[0041]

(Equation 23)

Step 8: The variable conversion unit 40 calculates the gains K ₁ , K ₂ , K ₃ , K ₄ , K ₅ , and K ₆ calculated as described above.
Is output to the FF control operation unit 14 and the FB control operation unit 16 of the control operation unit 10.

The derivation of Equations 6 to 16 will be described. Motor 1 which is a control target and / or its actuator
(In this specification, the called driver this), and the command current is a control signal u _k to the drive unit as an input, it can be expressed by the transfer function G for outputting the position of the drive unit (z).
Generally, the transfer function G (z) can be expressed by the following equation.

G (z) = K / s (sT ₀ +1) (17) where K indicates a gain, s is a Laplace operator, and T ₀ is a sampling period.

The transfer function G (z) can be expressed by the following equation when expressed in discrete time using the z parameter in the z coordinate system in accordance with the expression of the control method of the control operation unit 10 that performs sampling control.

G (z) = K (A + Bz) / (z−1) (z−P) (18) where T is a sampling period, and P = exp (−T / T ₀ ) (19) A = −T ₀ (P−1) −TP (20) B = T ₀ (P−1) + T (21)

FIG. 4 is a block diagram showing the control system shown in equation (18). The closed loop transfer function of the block diagram of FIG.

[0048]

(Equation 24)

Equation 22 can be expressed as Equation 23 by using poles and zeros in the z-coordinate system. As illustrated in FIG. 2, five poles are a ± bj, c ± dj, and e, and zero is f
± gj and -A / B.

[0050]

(Equation 25)

For simplicity, α ₁ ,
When α ₂ , α ₃ , and α ₄ are determined and the coefficients of the denominator polynomials of Expressions 22 and 23 are compared, fifth-order simultaneous equations represented by Expressions 24 to 28 are obtained.

[0052]

(Equation 26)

Solving these fifth-order simultaneous equations for the control parameters K 1, K 2, K 3, and K 4 of the feed forward (FF) control operation section 14 and the feedback (FB) control operation section 16 in the control operation section 10, results in FIG. Equations for calculating the control parameters can be derived from the pole arrangements a ± bj, c ± dj, and e illustrated in FIG. That is, control parameters K ₁ , K ₂ , K ₃ , and K ₄ can be obtained such that the poles of the transfer function of the control system coincide with a ± bj and c ± dj. However, strictly speaking, there are only four control parameters for five poles, so that all five poles cannot be freely arranged. Therefore, four poles a ± b
j, c ± dj are specified, and four control parameters and one pole satisfying these are determined. That is, the above fifth-order simultaneous equations are expressed by K ₁ , K ₂ , K ₃ , K ₄ and e
Solve for Thereby, Expressions 10 to 14 are obtained. At this time, e obtained by Expression 10 is solved.
Thereby, Expressions 10 to 14 are obtained. At this time, if the value of e obtained from Expression 10 is 1 ≦ e or e ≦ −1, the position of the pole exists outside the unit circle on the z plane, and the control system becomes unstable. . Therefore, in such a case, it is necessary to change the pole arrangement as described in steps 4 and 5 in FIG.

Similarly, by comparing the coefficients of the polynomials of the molecular formulas of Equations 22 and 23, the following simultaneous equations of Equations 29 and 30 can be obtained.

[0055]

[Equation 27]

The control system 1
Solving for the control parameters K ₅ and K ₆ of the feedforward (FF) control operation unit 14 and the feedback (FB) control operation unit 16 of Equations (15) and (1)
6 is derived.

As described above, the equations 15 and 16 for calculating the control parameters K ₅ and K ₆ can be obtained from the zero point arrangement f ± gj. In other words, control parameters K ₅ and K ₆ can be obtained from Equations 15 and 16 such that the zero of the transfer function of the control system matches f ± gj in the z-coordinate system.

The optimum pole arrangement calculator 60 for determining the coordinates of the poles and zeros in the z-coordinate system as input parameters to the variable converter 40 will be described. JP-A-8-1
In the optimal pole arrangement calculation in JP-A-71402, it has been described that the pole arrangement in which the disturbance response is optimal is a case where four poles overlap on the real axis and the real part of the quadrupole has the smallest value. However, in the PID control system disclosed in JP-A-8-171402, three pole positions: a ± b
Since only j and c could be designated, the optimum pole arrangement was determined while checking the position of another pole d. In the present embodiment, the four poles a ± bj and c ± dj can be arbitrarily specified, so that the fifth pole e is a value that stabilizes the control system, and the four poles a are within a range of −1 <e <1. Real parts a, c of
Can be selected as small as possible. The zero point f ± gj is described in Japanese Patent Application Laid-Open No. 8-171402.
As described in the publication, the response to the target value is best when the electrodes are arranged at the same positions as the poles. Therefore, in the optimum pole arrangement calculation in this embodiment, f = a and g =
Output as b.

The operation of the optimum pole arrangement calculation unit 60 based on the above technical background will be described with reference to the flowchart of FIG. FIG. 5 is a flowchart showing the operation of the optimum pole arrangement calculation unit 60.

Step 11: The optimum pole arrangement calculating section 60
Let a and c be initial values a = c = a0, respectively. Further, the optimum pole arrangement calculating unit 60 controls the control system so that the control system has no vibration.
= 0 and d = 0. At this time, it is necessary to select an initial value a0 for stabilizing the control system.
It is necessary to select a0 such that-(1-.epsilon.) <E <1-.epsilon. Here, ε is a sufficiently small positive number, and is a margin coefficient that gives a margin to stability. The margin increases as ε increases.

Step 12: The optimum pole arrangement calculating unit 60
Substituting a, b, c, and d into Equations 6 to 9 to obtain α ₁ , α ₂ , α
_3, to calculate the α _4.

Step 13: The optimum pole arrangement calculating unit 60
α ₁ , α ₂ , α ₃ , α ₄ , A, B, P, a, and c
And e is calculated.

Steps 14 and 15: Optimum pole arrangement calculator 6
0 determines whether or not-(1−ε) <e <1−ε. If − (1−ε) <e <1−ε, the optimum pole arrangement calculation unit 60 sets a = c = a−Δa (Δa means a minute a) in step 15, and again calculates the equation 6 Α ₁ , α ₂ , α ₃ , and α ₄ are calculated in accordance with Equation (9). Here, Δa takes an appropriate positive value in the step width for changing a and c.

Step 16:-(1-.epsilon.) <E <1-.epsilon.
If not, the optimum pole arrangement calculating unit 60 calculates a = c = a + Δ
a, and a and c are set to have the minimum value of-(1−ε) <e <1−ε.

Step 17:-(1-.epsilon.) <E <1-.epsilon.
If not, the optimum pole arrangement calculation unit 60 sets f and g for determining zero of the control system as f = a and g = b = 0.

Step 18: The optimum pole arrangement calculation unit 60 outputs the calculated values a, b, c, d, f, and g to the variable conversion unit 40, and ends.

The variable converter 40 determines the PID control parameters using the parameters determined by the optimum pole arrangement calculator 60 as described above.

As described above, in the optimum pole arrangement calculating section 60, the optimum pole arrangement is calculated with a = c = f and b = d = g = 0. It can also be set in the conversion unit 40. Further, the variable conversion unit 40 can also constitute a control operation unit for inputting such redundant variables in a fixed manner.

For example, among the variables used in the variable conversion section 40, redundant variables are fixed and a = c = f, b = d = g =
If it is set to 0 and only a is set in the variable conversion unit 40, a controller 100A as shown in FIG. 6 is obtained. Controller 100A
Is connected to a control operation unit 10, a D / A converter 20, a sampling circuit 30, a variable conversion unit 40A, a variable setting unit 50A, and an optimum pole arrangement operation unit 60 as shown in the figure.
The controller 10A includes a subtractor 12, a feedforward (F
F) A control operation unit 14, a feedback (FB) control operation unit 16 and an adder 18. Although the controller 100 illustrated in FIG. 1 and the control device illustrated in FIG. 6 have similar configurations, the configurations of the variable conversion unit 40A and the variable setting unit 50A are completely different. That is, in FIG. 6, a can be applied to the variable conversion unit 40A in a variable state as the variable setting unit 50A.

The processing in variable conversion section 40A at this time will be described with reference to FIG. FIG. 7 is a flowchart showing the processing in the variable conversion unit 40A in this case.

Step 31: The variable setting section 50A sets a in the variable conversion section 40A.

Step 32: c = f = a, b = d = g =
Set to 0.

Steps 33 to 39: The same as steps 12 to 18 illustrated in FIG.

FIG. 8 shows a calculation flowchart of the optimum pole arrangement calculation unit when a redundant variable is fixed. The operation contents of the optimum pole arrangement operation unit 60 are the same as the operation contents described above, but only the variable a to the variable conversion unit 40A.

Step 41: a, b, c, d, f, and g are fixed. Steps 42 to 46: Steps 12 to 1 illustrated in FIG.
Same as 6.

Step 47: The optimum pole arrangement calculator 60B outputs only a to the variable converter 40A.

The controller 100A of FIG. 6 has a lower degree of freedom than the controller 100 illustrated in FIG. 1, but can perform simple adjustment by fixing redundant variables.

Experimental Example An example of the embodiment of the present invention will be described below with reference to FIG. T0 = 0.413 (sec), K = 1247.0
The embodiment of the control method of the present invention is applied to the control target represented by The sampling interval is T = 0.1 (ms)
ec). The control result according to the present embodiment under this condition and the result according to JP-A-8-171402 are shown as comparative examples.

Comparative Example When the optimum pole was determined by the control device disclosed in Japanese Patent Laid-Open No. 8-171402, the position of the optimum pole was a = c = d = 0.818.
It was 7. The control parameters at this time were converted as follows by the variable conversion unit. Kp = 9.987, Ki = 49.1066, Kd = 0.007782, α = 0.531851, β = 0.871265 When the controller was operated with these control parameters,
A graph shown by a curve C1 in FIG. 9 was obtained. Curve R is a change in the target command.

This Example When the optimum pole was obtained based on the embodiment of the control device of the present invention, the position of the optimum pole was a = c = 0.557, and the other pole e was e = −0. .8627. At this time, the control parameters became the following values by the variable conversion unit 40. K ₁ = −0.836519, K ₂ = 378.7754, K ₃ = −695.541, K ₄ = 320.562, K ₅ = 315.463, K ₆ = −284.41 Controller using this control parameter When the control object was operated and controlled by operating the device 100, the result indicated by the curve A1 in FIG. 9 was obtained.

Comparing the comparative example disclosed in Japanese Patent Application Laid-Open No. 8-171402 with the example according to the embodiment of the present invention, the example according to the embodiment of the present invention has higher responsiveness (followability) to the target. High, high-speed servo control is realized. Further, although it cannot be confirmed only from the position response of the curve illustrated in FIG. 9, the response to disturbance has been improved since the pole arrangement farther from the origin has been realized, and good control performance has been realized.

That is, in the control method and control device of the present embodiment, four gains K ₁ , K ₂ , K ₃ , and K ₄
Performs feed-back control with three gains K ₁ , K ₅ , and K ₆ , so the degree of freedom in control parameter design is increased, and higher control performance than the conventional two-degree-of-freedom PID controller is achieved. Can be realized. In the control method and the control device according to the present embodiment, the influence of disturbance on the transfer function of the control system including the control target and the control means is minimized, and the positions of the poles and zeros in the optimal z coordinate system are determined. The control parameters K ₁ , K ₂ , K ₃ , K ₄ , K ₅ , and K ₆ are calculated by converting the calculated results into variables, thereby easily obtaining control parameters having desired characteristics. it can. Further, in the control means of the present invention,
The control system calculates the positions of the poles and zeros of the transfer function such that the control system exhibits the best control performance with respect to the target value and the disturbance, and calculates each control parameter by variable conversion based on the calculated values. The most suitable control parameter can be obtained, and the control parameter can be adjusted efficiently by avoiding the adjustment by trial and error.

The present invention is not limited to the above-described embodiment, but can take various modifications.
For example, in the above-described embodiment, the case where the position of the control target is controlled is illustrated, but the control target is controlled by angle control.
Alternatively, the present invention can be applied to other controls such as torque control and temperature control. In that case, encoder 2
Although 00 and the like need to be replaced with an angle detection sensor, a torque detection sensor, or the like instead of the position detection sensor, the sensor is selected according to the control purpose.

[0084]

According to the control method and control apparatus of the present invention, the conventional two-degree-of-freedom P
Fast operation and accurate control over that of the ID controller have been achieved.

According to the present invention, the control parameters used in the control method and the control device can be automatically calculated.
In addition, optimal control parameters could be calculated. According to this method, special knowledge and skill are not required for adjustment by a skilled person, and there is no need to spend time for adjustment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a servo control device according to an embodiment of the present invention.

FIG. 2 is a graph for analyzing stability in a z-coordinate system of a control target to be controlled in FIG. 1;

FIG. 3 is a flowchart illustrating a process of a variable conversion unit illustrated in FIG. 1;

FIG. 4 is a block diagram of a transfer function notation of a controlled object illustrated in FIG. 1;

FIG. 5 is a flowchart illustrating a process of an optimum pole arrangement calculation unit illustrated in FIG. 1;

FIG. 6 is a configuration diagram of a control device as a modified example of the control device illustrated in FIG. 1;

FIG. 7 is a diagram illustrating processing contents of a variable conversion unit illustrated in FIG. 1, and illustrating processing contents different from the processing method illustrated in FIG. 3;

8 is a flowchart showing a process of the optimum pole assignment calculation unit when a redundant variable is fixed with respect to the process of the optimum pole assignment calculation unit illustrated in FIG. 1;

FIG. 9 is a graph showing the results of an example based on the embodiment of the present invention and a comparative example according to JP-A-8-171402.

[Explanation of symbols]

 1, motor 2, motor driver 100, controller 10, controller 12, subtractor 14, feed-forward (FF) control calculator 16, feedback (FB) control calculator 18, adder 20 D / A converter 30 Sampling circuit 40 Variable conversion unit 50 Variable setting unit 60 Optimal pole arrangement calculation unit 200 Encoder

Claims (11)

[Claims] A target command r _k that controls 1. A controlled object or actuator, the deviation (r _k -y _k) and the actual value y _k of the controlled object or the actuator by the following formula 1-1 at each sampling period k based performs feedback control computation, the performs feedforward control operation based on the target command r _k by the following formula 1-2 at each sampling period k, the feed-forward operation result and ff _k and the feedback calculation result fb _k adding to, and controls the controlled object by driving the actuator based on the addition result u _k, the control method. (Equation 1) 2. The gains K ₁ , K ₂ , K ₃ , and K ₄ used in the feedback control calculation are respectively represented by the following equations 2-1 to 2-1.
Another gain K defined by the equation 2-4 and used for the feedforward control calculation
_5, K ₆ are defined respectively by the following formulas 2-5 and 2-6, the control method according to claim 1, wherein. (Equation 2) 3. A sampling means for reading a signal indicating an actual position or angle of a control target or an actuator at a predetermined cycle, and a target command r _k for controlling the control target or the actuator.
A deviation calculating means for calculating a deviation from the actual position or angle signal y _k read by the sampling means; and a deviation (r _k -y _k ) calculated by the deviation calculating means, for each sampling cycle k: a feedforward control operation means for performing feedforward control operation based and feedback calculation means for performing a feedback control operation, the following formula 3-2 at each sampling period k for the target command r _k based on equation 3-1, wherein feedforward calculation result the a ff _k feedback calculation result by adding the fb _k, the addition result controller and an addition means for controlling the controlled object by driving the actuator based on u _k. (Equation 3) 4. The gains K ₁ , K ₂ , K ₃ , and K ₄ used in the feedback control calculation are given by the following equations 4-1 to 4-1.
Another gain K used for the feedforward control calculation, which is defined by Expression 4-4.
_5, K ₆ each formula 4-5, as defined by Equation 4-6, the control device according to claim 3. (Equation 4) A target command r _k for controlling 5. A controlled object or actuator, the deviation of the actual value y _k of the controlled object or actuator (r _k -y _k) by the following formula 5-1 at each sampling period k based performs feedback control computation, performs feedforward control calculation for the target command r _k on the basis of the following equation 5-2 for each sampling period k, the feedforward calculation result ff
_k is added to the feedback calculation result fb _k, and a control parameter determination method for determining the gain in a control device that controls an object to be driven by driving an actuator based on the addition result u _k , ] The poles a + bj, c in the z-coordinate system of the transfer function of the control system such that the control system including the control target and the actuator exhibits the best control performance with respect to the target value and the disturbance.
+ Dj and the positions of the zeros f and g are calculated, and the gains K ₁ , K ₂ , K ₃ , and K used for the feedback control operation are calculated based on the following equation using the calculated poles and zeros of the transfer function. ₄ and other gains K ₅ and K ₆ used for the feedforward control calculation are calculated. Control parameter determination method. 6. A transfer function of a control system, wherein four poles a ± bj and c ± dj in a z-coordinate system are arbitrarily designated, and
The pole e is a value that stabilizes the control system. Within the range of -1 <e <1, a pole arrangement in which the real parts a and c of the four poles are as small as possible is selected. placed, f = a, and calculates the optimal electrode placement as g = b, the calculated the control parameter gain K ₁ based on the following _{equation, K 2, K 3, K} 4, the K _5, K ₆ Convert [Equation 7] Control parameter determination method. 7. Each of a and c is set to an initial value a = c = a0, and the calculated control parameters are set to gains K ₁ , K ₂ , K ₃ , K ₄ , K ₅ and K ₆ based on the following equation. 7. The control parameter determination method according to claim 6, wherein the conversion is performed. 8. The control system has b = 0, d =
A0 such that − (1−ε) <e <1−ε (where ε is a sufficiently small positive number) is selected, and the calculated control parameters are converted into gains K ₁ , K ₂ , K
_3, K _4, K _5, the control parameter determination method according to claim 6, wherein converting the K _6. 9. The method according to claim 9, wherein in the step of arranging the optimum poles, a, b,
Substituting c and d into the following equation to calculate α ₁ , α ₂ , α ₃ , α _4, and Substituting α ₁ , α ₂ , α ₃ , α ₄ , A, B, and P into the following equation to calculate e, It is determined whether or not − (1−ε) <e <1−ε, and −
If (1−ε) <e <1−ε, a = c = a−Δa (Δa means a minute a), and α ₁ , α ₂ ,
α ₃ and α ₄ are calculated, and unless − (1−ε) <e <1−ε, a = c = a + Δa, and a and c are set to − (1−ε) <
e <1-ε so that the minimum value is satisfied, and − (1-
7. The control parameter determination method according to claim 6, wherein f and g for determining the zero point of the control system are f = a and g = b = 0 unless ε) <e <1−ε. 10. A redundant variable is fixed and a = c = f, b =
7. The control parameter determination method according to claim 6, wherein d = g = 0, and only a is set in the variable conversion step. 11. The method according to claim 6, wherein c = f = a and b = d = g = 0.