JPS6095603A - Automatic control system for controlling object having time delay characteristic - Google Patents

Abstract

PURPOSE:To stabilize a revolving speed in a short time by selecting an advance rate and a return rate by a difference to a designated revolving speed, and adjusting a flow rate little by little by always returning a valve after advancing it. CONSTITUTION:A light reflecting zone is provided on the outside circumference of a rotor 2, a light of a light emitting element 8 is irradiated to said zone, and its reflected light is photodetected by a photodetector 9. A pulse from this rotation detector is counted by a frequency counter 10, and a revolving speed of a sample tube 1 is obtained. A designated revolving speed is inputted from a keyboard, etc., a changeover valve 6 is opened by a start signal S, and also a three phase pulse oscillator 12 is started. A central control device 11 compares a detecting signal from said counter 10 with a designating signal R0 and derives a difference D. A memory in this device 11 stores a table in which an advance rate and a return rate are set at every step by magnitude of said difference D, and basing on it, a flow rate control valve 7 is advanced and also returned, and its opening is adjusted. In this regard, the return rate is always smaller than the advance rate.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention (relating to a control system, particularly an automatic control system suitable for controlling an image that has a time variation of 1j1) ”
It is something that

[Prior Art] In the nuclear magnetic resonance system J3, a sample placed in a static magnetic field is rotated to homogenize the non-uniform components of the magnetic field, thereby increasing Ifi resolution. Nuclear magnetic resonance devices using flame-traversing magnets, which have recently become popular, also rotate the sample for this purpose. Because the magnet is placed in the same position, it cannot be expected to stabilize the rotation by using the braking force that is used to stir the air in the rotor attached to the sample tube, which is the case with a normal magnet. The rotation is stabilized by making it extremely large.

However, the intransitive verb r! is the number of rotations of a large rotating system. If you attempt to control using 11 circuits, the response speed to changes in the applied driving force will be extremely slow, so
For example, when using the proportional control method, as shown in Figure 1, 4-
This results in large hunting when starting up,
It takes a long time to stabilize and no measurements can be taken during that time. This also applies when changing the rotational speed, during which measurement must be interrupted. still,
In FIG. 1, the broken line shows the change in the rotational speed of the sample tube, and the solid line shows the change in the pressurized air flow m for applying rotational force to the sample tube.

[Object of the invention] The present invention has been made in view of the above-mentioned problems, and
The objective is to provide an automatic control method that can stabilize a rotating system with a large mass and a time delay characteristic in a short time.

[Structure of the Invention] The present invention includes (1) the step of detecting the state of the object and holding the detected value, (2) the step of calculating the difference between the detection (111) and the target value, (3)
A predetermined advancement rate corresponding to non-nuclear IQ,
(4) A step in which the controlled quantity is changed in one direction over a predetermined period of time; (5) After the change according to (4) above is completed, the process is left as it is for a predetermined period of time; (6) The process of repeating (1) to (5) above is repeated. It is characterized in that the advance rate d3 is set so that the return rate J,su・b becomes larger than (4). Hereinafter, the present invention will be explained in detail based on the drawings.

[Embodiment] Figure 2 is a block diagram showing an embodiment of the present invention. In the figure, J8 contains 1 ton of sample 11, J8 is 1 stone tube, 2 is taken as a part of the sample 1 color () [-J-Y, 3 is the sample 1'31 tube 1 and rotor. Reference numeral 2 is an air bearing (supporting data), and reference numeral 4 is a nozzle for spraying pressurized air onto the rotor 2 to rotate the sample tube. A compressor 5 generates pressurized air, and the pressurized air is sent to the nozzle 4 via a switching valve 6 and a flow rate regulating valve 7. A rotation detector consisting of a light emitting element 8 and a light receiving element 9 is arranged around the rotor 2, and its output is sent to a central controller 11 as a rotational speed signal via a frequency counter 10. The medium heat control device fJ 11 includes a rotation speed designation signal Ro and a start signal S.

A timing pulse from a three-phase pulse generator 12 that starts at the start (U) is supplied, respectively.

Reference numeral 13 denotes a pulse motor for changing the angle of opening of the flow rate regulating valve 7, and the pulse motor 13 adjusts the desired angle by driving pulses from a pulse oscillator 14 whose oscillation is controlled according to commands from a central controller. be turned or reversed.

In the JM construction as described above, for example, four light reflection bands are provided at 90° intervals on the outer periphery of the rotor 2, and when each light reflection band reaches a predetermined position, the light from the light emitting element 8 is reflected. 4 pulses per rotation are received from the rotation detector 1q, and the output of the frequency counter 10, which is counted by 81, is given by the rotation of the sample tube per second. A digital signal representing the number J is obtained.

Here, if the operator buffs the specified rotation speed from the keyboard etc. and commands star 1~, star 1~1
When the switching valve 6 hears "J" to No. 6 S, the three-phase pulse oscillator 12 starts, as shown in FIG. 3(a).

(b), (c) I display timing is in pulseless mode
-rEl.

It has Tb and Tc respectively, and the repetition period is 1-a + l
-b@-TC pulse signals Pa, Pb, and pc are repeatedly generated. This pulse signal causes the intermediate slit to have a control advance period of 1-a and a control return period of 1-a and a control return period of 1-b.
, and duration time Tc are respectively defined.

Then, at time to when period a begins, the central controller 11 compares the rotational speed signal from the frequency counter 10 with the specified signal Ro. Calculate the difference in numbers. Central control equipment 11
The internal memory stores the magnitude of the absolute value ID+ of [] as (1) lD'l≦2゜(2) 2<IDI≦5゜(3)
It is divided into five steps: D+≦20° (5) 20<l D I , and a table is stored in which advance rates and return rates are set for each step, for example, as shown in Table 1.

Table 1 The advance rate shown in J3 in Table 1 indicates how many percentage minutes the flow rate regulating valve 7 is to be advanced in the direction or open direction from the current state by dividing the period from fully open to fully open into 100 equal parts, and is the return rate. indicates the rate at which the opening/closing degree of the valve that has been advanced according to the advancement rate described above is returned to its original direction. As can be seen from Table 1, the return rate is always smaller than the advance rate, and it is true that the advance process and the return process are always performed as a pair in one control cycle. This is a feature of the invention.

FIG. 4 shows an example of rotation speed control performed using the above configuration. In the same figure, the broken line shows the output of the frequency counter 10, that is, the change in the rotation speed of the sample tube, and the solid line shows the change in the opening/closing degree of the flow m adjustment valve 7. The specified rotation speed is 20 rps (rotation 7
seconds), Ta=3.5 seconds, Tb=2.5 seconds, T c =
After 1 second, the central controller 11 reads to, tl, t. ,・
...and the rotation speed of the sample tube every 7 seconds.

First, at the start time to, the J3-C1 central control device 11 samples the rotational speed of the sample tube, and calculates the difference from the specified rotational speed. Since the sample O'31 tube is not rotating at this time, D becomes +20. The centrally controlled wage 1611 is based on Table 1, with the advance rate of (4) being 60%.

Select a return rate of 45% and turn off the flow m adjustment valve 7 for 3.5 seconds (T
a) Advance 60% from all 111 states, then advance 2°5
The flow rate was returned to 45% in seconds (Tb), and finally, after 6 seconds, the flow rate regulating valve 7 was adjusted to an opening degree of 15%.

Then, at tl 1 second (Tc) later, at J3, the rotation speed of the sample tube becomes 6 rps, and the central controller 11 outputs D-+14.
So, select (4) again, advance by 60% in 3.5 seconds, and return by 45% in 29.5 seconds. As a result, the flow rate adjustment valve 7 is in a state of 3o% after 6 seconds from Ll. adjusted to.

One second later, at 12, the rotation speed of the sample tube is 12r.
ps, and the medium heat control device 11 has D = + 8, so select (3) advance rate of 50% and return rate of 38% in Table 1,
It takes 3.5 seconds from t2 to advance by 50%, then returns to 38% over 2.5 seconds, and the diversion control valve 7 eventually reaches 1 after 6 seconds from t2.
It was adjusted to 70 degrees and 42%.

One second later, at 13, the rotation speed of the sample tube was 16r.
ps, iJ central control 1Liiff 11 it
Since D = +4, as shown in Table 1, 2) Select advance rate of 30% and return rate of 25%, advance by 30% over 3.5 seconds from t3, then move back by 25% for 2.5 seconds or tf -(' After all, the flow adjustment valve 7 is adjusted to an opening degree of 47% 6 seconds after t3.

One second later, at t4, it was 83 and the rotation speed was 18°5rp.
s, and the central controller 11 is D=+1.5, so the first
(1) Advance rate of 0% and return rate of 0% were selected in the table, and the adjustment of the J3 flow fii 1JiJ valve regulating valve 7 was stopped at this recycle, and the interval I11 was kept as it was.

The rotational speed at the next non-pull time t5 was 21 rps, and since the central controller 11 was +)--1, the adjustment of the flow rate regulating valve 7 was subsequently stopped, and the readiness remained at 47%.

Next sampling] 1, At time i t6, trial o'81
The rotational speed of the pipe is 22 rps and D = -24f, so the 1.9 section of the flow rate regulating valve 7 is stopped at -C, and the opening degree is 71.
It remained at 7%.

The next sampling is J3 at 11y interval 1"7, and the rotation speed of the sample tube is 22.5 rps, D--2, E, so
The central control unit 11 has an advance rate of 30% as shown in Table 1.

A return rate of 25% was selected. 1 = So, D's? 1F'j is negative C゛, the direction of 1 to advance is this: j, and the opposite,
That is, the direction is to restrict the flow rate, and the return direction is also reversed. Therefore, the peak 42 of the flow ω adjustment valve 7 reaches 6 seconds after the end 7.
% condition.

One second later, at t8, the rotational speed of the sample tube is 22.
rps and D--2, the central controller 11 again stopped adjusting the flow m regulating valve 7, and the angle of 68 degrees was maintained as it was.

At the next Zumbling time t9, the rotation speed of the test F4 tube at J3 becomes 21.5 rps, and thereafter the rotation speed is 2o±2 rps.
was maintained in the range for a long time, and the flow m adjustment was also stopped during that time.

[Effect] As can be seen from Figure 4, this Komei samples the rotational speed, selects the advance rate and return rate based on the difference from the specified rotational speed, and always returns after advancing to adjust the flow rate little by little. Because of this, there is extremely little hunting and the rotational speed can be stabilized in a short period of time.

Needless to say, the rotation can be stabilized in a short time not only at the time of starting, but also when changing the rotation speed midway through.

Further, if the steps in Table 1 are further divided, more accurate control becomes possible, and it goes without saying that the advance rate and return rate of each step must be set appropriately depending on the object to be controlled.

Further, as the central control device, a computer may be used, or individual circuits may be combined to form an lt4. When combining circuits individually, the same operation can be performed using a code converter or the like without necessarily using a memory that stores the conversion table shown in Table 1.

Further, the present invention is not limited to the test tube rotation mechanism used in a nuclear magnetic resonance apparatus, but can be widely used in automatically controlling objects having time delay characteristics.

[Brief explanation of drawings]

Figure 1 shows the hunting that occurs in the conventional control method.
FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a diagram showing the output pulses of a three-phase pulse oscillator, and FIG. 4 is a block diagram showing the configuration of an embodiment of the present invention. This is a diagram showing an example. 1: sample tube, 2: rotor, 3: stator, 4: nozzle,
5: Compressor, 6: Cut-off valve, 7: Flow m adjustment valve, 8:
Optical detector, 9: Light receiver, 10: Frequency counter, 11
z medium heat control 211 device, 12: 3-phase pulse oscillator, 13
: Pulse motor, 14: Pulse oscillator. Patent applicant: Mr. Ikuo, representative of Honda Electronics Co., Ltd.

Claims (1)

[Claims] An automatic control method for controlling an object having time delay characteristics, comprising: (1) detecting the state of the object and obtaining a detected value; (2) determining the difference between the detected value and a target value; (3) changing the controlled port in one direction over a predetermined period by a predetermined advance rate corresponding to the value of the difference; (4) changing the controlled port in one direction by a predetermined advance rate corresponding to the value of the difference; (5) After the change according to (4) above is completed, the head is released for a predetermined period of time. Step (6) Repeating the steps (1) to (5) above, and setting the advance rate in (3) to be greater than the return rate in (4). A control system that takes 14 characteristics.