how to write PID function in .m file

i need a pid function in my m file. could anyone please write the function.

[Hero]

I do have same question

[PUJARI MURAGA]

You are having state space model. Suppose I have differential equations then is it possible to do without converting them in state space/laplace ?

Answer 1

[Arkadiy Turevskiy]

This demo might help.

Arkadiy

[sujan]

thank you,

but my model is a space state model, and it has many tf. and i dont know how to connect space state form and PID controller. so could you please tell me how to use PID in m file which is not in tranfer function. thank you Arkadiy

[Arkadiy Turevskiy]

well, how many inputs and outputs does you system have? If is a single-input-single output system, then everything shown in the demo is still applicable.If you more comfortable dealing with transfer functions, convert your state space system to a transfer function using tf:

ss_sys=ss(a,b,c,d);

tf_sys=tf(ss_sys);

Answer 2

[Krishnendu Mukherjee]

a way is there : suppose ur tf is (1/a+s) which is to be fed to a pid controler. then the overall tf will be: (Kp+Ki/S+Kd.S).(i/S+a)/(1+(Kp+Ki/S+Kd.S).(i/S+a)). now if you want to give step input then : num=[............] den=[............] tf=num/den ster(tf) so you have to transfer the PID and the tf to a overall transfer function.

[sujan]

thank you,

but my model is a space state model and its has 9 state parameters. and i dont know how to use PID in my system. and it is a MIMO system. 4 inputs and 9 outputs. so could you please help me to write a PID function for space state form not in tf. thank you

Answer 3

[Daniel]

Please where's the demo? I'm also trying to write a matlab function for pid using the user-defined function block

[Arkadiy Turevskiy]

html link added back

[Suyog]

How to write pid function in m file

[Sam Chak]

Hi @sujan

1. You can use the pid() function directly.
2. You can describe that in transfer function.
3. You can model it using the descriptor state-space.
4. Finally, you can put the pid equation in the way that is similar to the ordinary differential equation (ODE).