With the rapid development of computer technology, thermostatic element the application field of computer is more and more extensive. Digital computer has been widely used not only in scientific calculation and data processing, but also in the field of control system design. The basic application of digital computer in the design of control system is to directly participate in the control, assume the task of controller in the control system, thus forming the computer control system. The design method of computer control system is also similar to that of continuous system, which can be divided into classical design and modern control theory design. The classical design method is mainly based on root locus method and frequency method. No matter which method is adopted, the design of the controller is much more complicated than that of the continuous system. Manual calculation is impossible and digital simulation technology is needed. Through the design of the controller based on the root locus method, the corresponding controller can be successfully formulated for a given object. The model is simulated and the results are analyzed. The improvement of the controller design is discussed, and the advantages and related problems are appropriately analyzed and discussed. The root locus method is a method to determine the relationship between the closed-loop pole distribution and the loop gain. Moreover, after simple generalization, this method can be used to select some parameters other than the loop gain, so that the poles of the closed-loop system can be distributed at or near the predetermined position.
The root locus can be used to study the relationship between the parameters of the controlled object and the closed-loop stability, and the approximate time response of the closed-loop system can be obtained by analyzing the position of the closed-loop poles.
Controller is an essential component of any industrial control system, and it is one of the important foundations of the control system. The significance of designing controller based on root locus method is that it can greatly improve the stability of the system and effectively guarantee the accuracy and reliability of the system.
Stability is not only the important performance of the system, but also the primary condition for the system to work. This is because, in the actual operation of the system, some external and internal factors are more or less disturbed. If the system is unstable, it will deviate from the original equilibrium state under the action of these disturbances. And with the passage of time and divergence. Therefore, how to analyze the stability of the system and find out the measures to ensure the stability of the system has become a basic task of the automatic control theory. There are many definitions of stability. Typically, there are two kinds of definitions: one is the equilibrium state stability first proposed by Lyapunov, a Russian scholar, and the other is the motion stability of the system. For linear systems, the two statements are equivalent.
The effect of value change on system behavior: In the poles of control system, a pair of isolated conjugate complex poles closest to the imaginary axis have a major impact on the system’s transition behavior, which is called dominant pole pair. It is used to analyze the influence of additional links on the performance of control system. For some purpose, it is often necessary to introduce additional links in control system, which is equivalent to introducing new open-loop points and open-loop zeros.
The influence of additional links on system performance can be estimated by root locus. Correction device for design of control system: Correction device is an additional part of the system to improve the performance of control system. Its type and parameter design can be determined by root locus. Root locus is short for root locus. It is the locus of characteristic equation of closed-loop system in s plane when a parameter of open-loop system changes from zero to infinity. When there is no zero and pole cancellation in closed-loop system, the root of closed-loop characteristic equation is the pole of transfer function of closed-loop system. We often call it closed-loop pole. Therefore, finding the distribution of the closed-loop poles from the zero of an open loop, the position of the poles and some variable parameters is actually solving the problem of finding the root of the closed-loop characteristic equation. When the order of the characteristic equation is higher than the fourth order, the process of finding the root is more complicated. If we want to study the influence of system parameter change on closed-loop characteristic equation, we need a lot of repeated calculation, and at the same time, we can not directly see the trend of influence. Therefore, the analytical method is inconvenient for finding the roots of higher order systems. On the graph, the thick solid line is called the root locus of the system. The arrow of the root locus indicates the changing trend of the root locus with the increase of K value, while the labeled value represents the value of the open-loop gain K corresponding to the closed-loop pole position. The arrows on the root locus indicate the changing trend of the root locus with the increase of K value, while the labeled values represent the open-loop gain K corresponding to the closed-loop pole position. Series lag controller (a < 1) is mainly used to improve the open-loop amplification coefficient of the system, but has no effect on the dynamic performance of the original performance. Draw the root locus of the uncorrected system.
The layout of the zero ZC and the pole of the controller on the s plane is determined. The root locus of the corrected system is drawn, and the dominant poles of the closed-loop system are found according to the performance index on the new root locus. According to the re-determined closed-loop dominant pole, the corresponding open-loop amplification factor is calculated according to the amplitude condition, and the performance index is finally checked. This paper briefly introduces the controller design of root locus method. The root locus method is undoubtedly to add advanced, lagged, zero-pole cancellation or three integrated links to the original system to achieve the desired control objectives, and ultimately to stabilize the system. Because the root locus method can be realized by computer simulation, the control that the previous manual algorithm can not achieve can also be realized now, and can be concise and concise in the form of graphics in front of us. Its advantages are: good stability and high accuracy.