JPS58119004A - Bang-bang control method - Google Patents

Abstract

PURPOSE:To reduce an overshoot by supplying a command value obtained by subtracting an estimated overshoot value from a desired value, and performing switching from the command value to the desired value when the amount of the overshoot approximates the desired value. CONSTITUTION:To the automatic speed controller ASR10 consisting of a speed control element 1, limiter 2, feedback element 6, and adder 7, the control circuit consisting of a bang-bang element 9 and an adder 8 is added. The theta of the bang-bang element 9 corresponds to the amount of an overshoot when such an input that the limiter 2 is saturated is applied and the command value obtained by subtracting the value theta from the desired value is applied to the speed control element 1 through the adder 8. As the output of the adder 7 approximates the desired value, the theta approximates zero under the control of the bang-bang element 9 to perform less-overshoot speed control. Thus, while starting time is held short, the amount of the overshoot is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bang-bang control method, and particularly to a bang-bang control method that enables quick response and small overshoot control.

Generally, the controlled quantity of the controlled object (speed, position, temperature flow rate, etc.)
In a control system for achieving a target value given from an external source, it is necessary to quickly approach the target value, reduce vibrations caused by overshoot, and shorten the settling time.

FIG. 1 shows a conventional motor speed control system as an example of such a control system, in which speed control elements 1. Limiter 2. Feedback element 6. It consists of an automatic speed regulator (hereinafter abbreviated as AIR) 10 consisting of an adder 7, and a self-made current 11 represented by a -th order lag element (hereinafter abbreviated as ACR) 3, and is controlled as a control object. The motor has a torque constant of 4°, a rate of inertia of 5, and a torque disturbance TL.

In such a control system, depending on the purpose of the control, the speed may or may not decrease when the load (corresponding to TL in Figure 1) changes, or the speed command may change in steps. In such a case, there are cases where overshoot is acceptable and cases where there should be no overshoot. Depending on these conditions, the transfer function Gn of the speed control element 1 is selected for each case as shown in Table 1. It was used.

Table 1 Among these, especially when speed reduction is not allowed even if the load changes (offset error 0), the proportional integral element G is used as Qlm as shown in Table 1. In this case, the speed Overshoot when the command changes is unavoidable. Further, even if an offset error is allowed, the first-order lag/advance element G is used even when a fast response is required, which again has the disadvantage that overshoot is inevitable.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a pumping control method that makes it possible to significantly reduce the amount of overshoot even in systems that require high precision settling and quick response. It is in.

The present invention estimates the overshoot amount in advance, gives a command that subtracts the overshoot amount from the originally intended target value, and then switches the command value to the target value when the overshoot amount approaches the target value. It is characterized by the following.

Hereinafter, the present invention will be explained in detail using examples. FIG. 2 shows an embodiment in which the present invention is applied to the conventional motor speed control shown in FIG. 1, and is characterized in that an adder 8 and a bang-bang element 9 are added to ASRlo. Here, θ shown in the bang-bang element 9 corresponds to the amount of overshoot when a step input that saturates the limiter 2 is applied, and ε is a threshold value determined by the system. The bang-bang element 9 and the adder 8 change the target value to reduce the overshoot t, and its operation will be explained using the time chart of FIG.

Now, as shown in FIG. 3, the target value ω0 is ω. =0 to ω
02a in a stepwise manner, ``the response speed ω at the output of the feedback element 6, and this and the target value ω. In the case of the conventional method, the deviation δ from the third
The response is shown by the solid line in the figure. In other words, the start-up is extremely fast and there is no offset (4), but the settling time is long due to overshoot, and 1 = 1 in the figure. It lasts for about a while.

However, in this embodiment, the target value human power ω. -a(〉C), a-θ, which is obtained by subtracting θ of the bang-bang element 9 output from the output a<t=ta> of the adder 7, is the initial deviation δC (dotted line in Figure 83), which is gradually decreases (this corresponds to the apparent target value a becoming a-θ).

Then, when the output of the adder 7 reaches ε at t-duplex, that is, when the δ value of the solid line in FIG. is one θ+
Changes from ε to ε. Moreover, the time required up to this point is such that the system starts up at a high speed, so even if the target value decreases from a to a-0, it will start up in a short time, with almost no change.

Here, θ is the overshoot amount when applied to the limiter in the conventional method, as shown in speed response ω1 in Figure 3.
l is chosen to be equal, and ε is the control deviation to be spoofed,
In other words, the conventional 1=1, which can be considered to have stabilized. If the value is about the deviation in , then t=t! Then, the deviation becomes small as δ=e, and the target value at that time is ω. =a (note that θ=0), so ω has reached ω, =a−ε, which is extremely close to the target value a.

Therefore, the speed response ω, (track separation) according to the present invention is t=11
When the target value a has been reached, a nearly minute step input change -ε appears to be re-inputted, and the bank-bank element 9 is activated (δ decreases ε), and rapidly changes ω,
is set to the target value a.

According to the experimental data of the above embodiments, by using the present method in a system having an overshoot of 1β chi using the proportional integral element of the conventional method, it was possible to reduce j to 91.5%.

As described above, according to the present invention, it is possible to know the amount of overshoot when an input is applied that causes the limiter 2 to reach the saturation value, and if an appropriate C determined by the system is given, the control constant can be adjusted. This has the effect that the amount of overshoot can be easily reduced without requiring special adjustment and without degrading performance by lowering the loop gain.

Fig. 1 is a block diagram showing a conventional motor speed control system, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a control system according to the conventional method and the method of the present invention. It is an explanatory diagram of a step response in .

1...Speed control element, 2...Limiter, 4...Torque constant, 5...Inertia factor, 6...Speed feedback Sankiju 1 Figure 2

Claims (1)

[Claims] 1. A bang-bang element is provided that generates an output as large as a foot when the deviation between the controlled variable of the controlled object and its target value exceeds a predetermined threshold, and the output of the bang-bang element is Control the deviation value obtained by subtracting it from the deviation! Simply input the control l! 9. A bang-bang control method characterized in that the controlled quantity is controlled by the wood ratio output.