There are many ways to classify automatic control systems.
① According to the type of control device, it can be divided into conventional control and computer Control two. Analog controller is used for conventional control (see control instrument), computer Control adoption Electronic digital computer 。② It can be divided into closed loop according to whether there is feedback or not Control system and Open loop control system 。 ③ It can be divided according to whether the set value is fixed Constant value control system And servo control system. Constant value control system The control system can automatically overcome the influence of disturbance and keep the controlled variable basically constant. Follow-up Control system The set value in is variable, and the system makes the controlled variable change with the set value. For example, in chemical production, the flow of material A is required to maintain a certain ratio to the flow of another material B. If the flow of material B changes, the flow of material A must change accordingly flow control It belongs to the follow-up control type. dispersed control theory It is also widely used in calculation, for example, square root: Formula: X (n+1)=Xn+[A/X ^ (k-1) - Xn] 1/k
For example, we derive the third power, that is, K=3;
Formula: X (n+1)=Xn+[A/X ^ 2-Xn] 1/3
For example, A=5, 5 is between the 3rd power of 1 and the 3rd power of 2, X0 can take 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0. Suppose we take 2 as the initial value:
Step 1: 2+(5/2x2-2) 1/3=1.7=X1
Step 2: 1.7+(5/1.7x1.7-1.7) 1/3=1.71=X3
Step 3: 1.71+(5/1.71x1.71-1.71) 1/3=1.709=X4
Step 4: 1.709+(5/1.709x1.709-1.709) 1/3=1.7099=X5
Each calculation is one more digit than the previous one, and the number of calculations is proportional to the accuracy. If the value is too large, the formula will automatically decrease, such as Step 1 and Step 2. If the value is too small, the formula will automatically increase, such as Step 3 and Step 4. [1]
