MPC cannot be designed in app

I have a Carsim S-functon as the plant model for a MPC. But I get an error saying "Plant model cannot be a pure direct feed-through system without additional dynamics". Why does it keep saying that?

[Pengshan Dai]

I have the same problem, do you have a solution already?

[Dhruv Thakkar]

@Pengshan Dai I didn't. Please share the solution if you get it.

[Kumar Prabhakar]

SIR HAVE YOU SOLVED THE SAME PROBLEM

TELL ME HOW

[zhanglong zhang]

hello, i also have the problem,may you tell me how can i solve it? thank you.

Answer 1

[Junhao Jiang]

The compatibility between CarSim and Simulink is not high,if you have the state space,you should use it,or you only choose the s-function to make it.

[Dhruv Thakkar]

Hey, thanks for the reply. I do have the state-space, but I also want to capture the non-linearity and actuators delay which are difficult to model. Plus, I wil have no way to verify since I don't have actual vehicle data. Since Carsim is a high fidelity simulator I chose it. I didn't get the last thing you wanted to say.

[Pacifique Turabimana]

How can I add CarSim S-Function in Simulink Library?

I tried to link CarSim with Simulink but nothing to do after because I can't find CarSim in Simulink library, I tried even online MATLAB but I can't be ab;e to continue working on my research. Please guide me to solve it.

[Walter Roberson]

Unfortunately carsim.com does not appear to post their installation documentation online :(

Answer 2

[Walter Roberson]

According to https://www.mathworks.com/matlabcentral/answers/473358-mpc-controller-direct-feedthrough-from-manipulated-variables-to-any-output-in-plant-is-not-allowed#comment_961921 you currently have an output that is being calcuated from an input signal with no modeled delay, but MPC does not permit that. You need to configure your model to take some time between input and output for all signals.

You can use delay blocks, or you can use a transfer function.

https://www.mathworks.com/help/control/ug/time-delays-in-linear-systems.html

https://www.mathworks.com/matlabcentral/answers/42300-how-can-i-implement-time-delay-transfer-functions-in-simulink-250-e-s-20-s-1-s-10

[zhanglong zhang]

I added the delay module, but this is still the mistake. Please kindly guide me. Thank you very much.

as shown below:

[MUHAMMAD]

How did you solved this problem? I am facing same problem

[MUHAMMAD]

Solution:

I had same problem and It is solve by adding time delay.

You can add time delay in between MV and plant. I did using matlab command like like

plant = tf([num],[den],'OutputDelay',1.5 )

I hope this answer helped you.

Example

%%Transfer Function By System identification
num = [-1.324 6.6e05 -6.914e09 5.128e13 -1.054e19]
den = [1 1.99e04 1.371e09 1.145e13 4.037e17]
plant = tf([num],[den],'OutputDelay',1.5 )

[JGP]

can you help me? Even if I use the delay or LTI system, the error continues.

How do I insert the Matlab code you mentioned into Simulink?

Answer 3

[MUHAMMAD]

Solution:

I had same problem and It is solve by adding time delay.

You can add time delay in between MV and plant. I did using matlab command like like

plant = tf([num],[den],'OutputDelay',1.5 )

I hope this answer helped you.

Example

%%Transfer Function By System identification
num = [-1.324 6.6e05 -6.914e09 5.128e13 -1.054e19]
den = [1 1.99e04 1.371e09 1.145e13 4.037e17]
plant = tf([num],[den],'OutputDelay',1.5 )