how to represent this state space model in matlab using A,B,C,D matrix?

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senthil kumar 2015-8-13

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评论： senthil kumar 2015-8-19

In this x5dot equation there is a term like sgn(x6)*x5/Aa*x6. how to enter this term interms of A B C D matrix in state space.

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Sebastian Castro 2015-8-14

在 MATLAB Online 中打开

Don't know what your error message was (you should always include that), but I copied your code over and it worked for me after one change.

The ode45 expects a function handle, which you can find by putting an @ character in front of the function name as follows:

[t,x]=ode45(@cktt,tspan,x0);

... Now, when I look at the results, it seems like the only state that gives me a non-NaN output is state 6. However, the code runs and you can look into the equations now to see if they're okay :)

- Sebastian

senthil kumar 2015-8-19

thank you for your reply. now i written simulink code for entire active suspension. i attached file here. when i ru n the simulation , i am geeting singularity error at integrator.i tried many things. it wont work. something wrong in that integrator which i dont know. please help me.

Actually i written simulink code for above equation only.i changed diffrent solver, and tolerance value. but not acting any answer.getting singularity error at integrator in actuator.

i attached file with PID when i run without connecting PID. it is working correctly. when i connect ,it wont work. i took some random value for PID intially.

ALso i put some saturation value for integrator inside actuator.then only it will work. without saturation value it gives singularity error.

something wrong in integrator which i dont know.please help me in that point.i attached road input also . the values of constant are there in simulink file.

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Answer 1

Sebastian Castro 2015-8-13

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As soon as you introduce nonlinearities like that square root and the "sgn" function, you cannot express a system using state-space.

The two ways to create nonlinear models both involve implementing each of the above first-order equations in the form xdot_k = f(x_1,x_2,...,x_k,...x_n-1,x_n). These are: