table of Contents

1. Solve differential equations using an integer

1.1 Solving steps

1.2 Examples

2. The difference between simulink block diagram and control system block diagram

 

 

I just started learning simulink, and always confused the simulink block diagram with the control system block diagram, which resulted in the inability to correctly obtain the corresponding differential equation based on the simulink block diagram or the corresponding block diagram based on the differential equation. This article, I hope to help everyone ~

 

1. Solve differential equations using an integer

1.1 Solving steps

1) First move the term with the highest order in the differential equation to the left side of the equation, and move the remaining terms to the right side of the equation (try the lower term if it cannot be separated);

2) Determine the number of variables in the differential equation, the general variables contain time variables, if there are N variables, there are N-1 main lines

3) Draw the main line

4) Draw the smulink block diagram according to the main line and the differential equation

5) Combine the N-1 main lines according to a certain relationship

6) Output the final result

1.2 Examples

Find the following differential equation

1) First move the term with the highest order in the differential equation to the left side of the equation, and move the remaining terms to the right side of the equation (try the lower term if it cannot be separated);

 

2) Determine the number of variables in the differential equation, the general variables contain time variables, if there are N variables, there are N-1 main lines

by

It can be seen that the equation contains three variables, which are x, y, t, where t is the abscissa, a function of y is required, so there are two main lines, respectively, x, y

 

3) Draw the main line

What is the highest derivative order of the main line? The main line generally needs as many integration modules

 

4) Draw the smulink block diagram according to the main line and the differential equation

5) Combine the N-1 main lines according to a certain relationship

6) Output the final result

Complete the block diagram on the main line according to each item of the differential equation, and finally connect it with the sum or add function

Add initial conditions: double-click the integration module to set

Note: The initial value represents the initial value output by the integration module

Display initial conditions: select the module-right button-propriet ...

Drawing display results through scope

Reference to other examples: Reprinted from Huashan LunjianSimulink modeling for solving differential equations》

 

7) Simulation:Click run to run the simulation, double-click scope to view the results

 

8) Error correction

Because the new version does not support the direct use of t, we can change t to something else

The fun module can only use u as the name of the variable

2. The difference between simulink block diagram and control system block diagram

The simulink block diagram emphasizes the transfer relationship of variables. Without the transfer function, the loop is simply to pass the variable expression at the beginning of the line to the terminal of the line:

And the control system block diagram, the expression is obtained by the output = input X transfer function

 

See the appendix for the simulink block diagram six file of this case