JPH05241608A - Pid controller - Google Patents

Abstract

PURPOSE:To accelerate operation and to lower the error rate of a control part by providing a first circuit for operation the derivative expression of a PID arithmetic expression and a second circuit for integrating the arithmetic result of the first circuit at the control part. CONSTITUTION:A motor 31 is driven by a motor driving device 30, and a bobbin 34 is rotated by the motor 31. A wire body 33 is stretched at a dancer roll 32 and taken up at low speed by the bobbin 34 to execute control for decelerating speed while being thicker by winding. The upside/downside of the dancer roll 32 is detected as a derivative value (e), sampled by a sampling circuit 1 and afterwards inputted to a derivative arithmetic circuit 21 as a digital sampling value en by an A/D converter 5. An output Yn of a differentiation/ integration circuit is converted to an analog manipulated variable (y) by a D/A converter 15, added with a reference velocity command (v) by an adder circuit 10 and impressed to the motor driving device 30. Only the addition/ subtraction is enough as arithmetic, labor is saved and acceleration is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a PID controller,
In particular, digital PI that aims to speed up and improve reliability
D control device.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional PID controller, which includes an adder 10, a PID controller 20, and a controlled object 30 controlled by the PID controller 20.

In the above configuration, when the predetermined set value x ₀ for controlling the controlled object 30 is given to the adder 10, the control variable x and the set value x ₀ output from the sensor or the like provided in the controlled object 30. Deviation e is input from the adder 10 to the PID control unit 20. PID control unit 2 with deviation e input
0 is P including proportional calculation P, integral calculation I, and differential calculation D
ID calculation is performed and the manipulated variable y is output. Controlled object 30
Accepts the manipulated variable y and performs an operation based on it.
By this operation, the control variable x provided in the controlled object 30 and detected by the sensor or the like is fed back to the adder 10.

In recent years, PID control devices have become digital due to the widespread use of microcomputers. Of FIG.
(a) and (b) are comparisons between an analog PID control device and a digital PID control device, and (a) shows the same analog PID device as in FIG. 4, so description thereof will be omitted, but (b)
The digital PID control device will be described below.

As shown in FIG. 6, this PID control device samples the set value x ₀ at times t _n-2 , t _n-1 and t _n of a cycle t _P to sample value x _{0 (n-2).} , X _{0 (n-1)} , x _0n , and A / D for A / D converting the sampling value output from the sampling circuit 1.
The D converter 5, the hold D / A converter 15 that holds the digital manipulated variable Y _n output from the PID control unit 20 and outputs the analog manipulated variable y by D / A conversion, and the control variable of the controlled object 30. a sampling circuit 11 for outputting a sampling value x _n by sampling the x, sampled value x _n output from the sampling circuit 11 a
It has a configuration in which an A / D converter 25 which performs D / D conversion and feeds back to the adder 10 as a digital signal x _Dn is newly added, and the PID control unit 20 performs digital calculation. This digital operation is based on the conventional analog PID
Arithmetic expression Instead of. Since the whole operation is obvious from the analog PID control device, it is omitted here.

The digital PID control unit 20 is shown in FIG.
As shown in (b) and (c), the CPU section 20a and the output section 20b
Is included. In the figure, × indicates a failure, and ○ indicates a state without abnormality. Considering the failure of the PID control unit 20, there are three cases (a), (b), and (c).
Since the U section 20a has more parts than the output section 20b, (a)
Is the most common case.

When a failure occurs in the PID control unit 20, there are four possible cases shown in (a), (b), (c) and (d) of FIG. (a) The control output becomes zero. (b) The control output becomes 100%. (c) The control output becomes unstable. (d) The control output holds the value immediately before the failure. As shown in (d) of FIG. 8, the PID control device preferably holds the control output immediately before the failure even if the failure occurs.

[0008]

However, according to the conventional digital PID control device, in order to improve the control accuracy, it is necessary to shorten the sampling period and speed up the sampling. As a result, the amount of calculation increases with an increase in the sampling amount, so that a high-speed CPU must be used. Further, since the digital PID control unit includes the integral calculation, there is a limit to the speeding up of the calculation speed, and if a CPU with a large number of parts is used for speeding up, the probability of failure becomes high. The failure of the CPU is (a), (b), (c), (d) in FIG.
Since it is not known which of the above results will lead to a decrease in reliability.

Therefore, an object of the present invention is to provide a PID control device capable of increasing the operation speed and improving the control reliability.

[0011]

SUMMARY OF THE INVENTION In view of the above problems, the present invention sets an input signal corresponding to an operation parameter of a controlled device to P in order to increase the operation speed and improve the control reliability.
The means for outputting the first operation result based on the operation expression obtained by differentiating the ID operation expression, the means for integrating the first operation result and outputting the second operation result, and the second operation result are input. The PID control device includes means for approximating the operating parameter of the controlled device to a set value.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the PID control device of the present invention will be described in detail below with reference to FIG.

In FIG. 1, the motor 31 is driven by the motor driving device 30, and the bobbin 34 is driven by the motor 31.
Is rotated. The filament body 33 is stretched around the dancer roll 32, and is wound around the bobbin 34, which is controlled to reduce the speed by the winding weight, at a constant speed. Dancer roll 32
The upper and lower sides of are detected as deviation value e, and sampling circuit 1
After being sampled by the A / D converter 5, the differential operation circuit 21 outputs the digital sampling value e _n by the A / D converter 5.
To enter. The digital PID calculation formula is, as described above, Becomes Differentiating this with respect to time, Becomes The differential operation circuit 21 outputs the differential operation result Y _'n. The output _Y'n is integrated by the integration calculation circuit 22 and the integrated output Becomes This output Y _n is D by the D / A converter 15.
/ A converted to analog manipulated variable y,
The addition circuit 10 adds the reference speed command v to the motor drive device 30. In the above equation, K _P , θ,
T _I and T _D are constants set arbitrarily. As apparent from the above equation, calculation of Y _n 'is e _n, since the _{e n-1, e n-} 2 may only addition and subtraction in a constant cycle, operation is very abbreviating. On the other hand, the integrating circuit 22 only needs to perform the integral calculation. From these results, the calculation speed can be increased and the failure rate can be reduced.

2 and 3 show the second and third aspects of the present invention.
In this embodiment, the furnace temperature is controlled by controlling heaters 41, 41 ₁ , 41 ₂ , ... 41 _n for heating the furnace 43, which have a slow control speed. The furnace 43 uses the temperature measuring devices 42, 42 ₁ , 42 ₂ , ... 42 _{n to} measure the furnace temperature T _x.
Is detected, the set temperature T ₀ is subtracted by the adder 10, and the subtraction result t = T _x −T ₀ is calculated by the integration calculation circuits 21, 21 ₁ , 2
1 ₂ ... 21 _n , and the integration calculation circuits 22, 22 ₁ , 22 ₂ ... 22 _n are input as in the first embodiment.
Through the heating devices 40, 40 ₁ , 40 ₂ ,
A control variable is given to 40 _n .

The third embodiment of FIG. 3 is a parallel control system, but it can be easily executed by copying one program. Further, the first to third embodiments can be further modified by combining only P control, PI control and the like.

[0016]

As described above, according to the PID control device of the present invention, the first circuit for calculating the differential formula of the PID calculation formula and the second circuit for integrating the calculation result of the first circuit are controlled. Since it is provided in the section, the calculation speed can be increased and the failure rate of the control section can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional PID control device.

FIG. 5 is a block diagram showing a conventional PID control device divided into an analog type and a digital type.

FIG. 6 is an explanatory diagram showing digital sampling.

FIG. 7 is an explanatory diagram showing a failure of the control unit.

FIG. 8 is an explanatory diagram showing an output state when the control unit has a failure.

[Explanation of symbols]

1 Sampling circuit 5 A /
D converter 10 adder 15 D /
A converter 20 control unit 21 differential operation circuit 22 integration operation circuit 30 control target (motor drive device) 31 motor 32 dancer roll 33 linear body 34 bobbin

Claims (1)

[Claims] 1. A first expression based on an arithmetic expression obtained by differentiating an input signal corresponding to an operation parameter of a controlled device from a PID arithmetic expression.
And a means for integrating the first operation result and outputting a second operation result; and inputting the second operation result for setting the operation parameter of the controlled device. A PID control device comprising means for approximating a value.