After building actuation system using Isothermal Liquid blocks (IL) in Simscape its showing error

After building actuation system using Isothermal Liquid blocks (IL)(R2023a) in Simscape i got it connected to the MPC but it showing Plant model cannot be a pure direct feed-through system without additional dynamics but when i used the hydraulic blocks (R2020a) the plant got imported in mpc. Why the error coming while using IL block in simscape?

Answer 1

[nick]

Hi Kiran,

I understand that you are looking to debug the following error:

Plant model cannot be a pure direct feed-through system without additional dynamics error.

Kindly provide the complete model & files associated with this error. MPC Controllers include a linearized plant model. If the model linearizes to "ss(0,0,0,0)", then the above error message will appear.

You can resolve the error by the following the below mentioned steps:

• Try specifying input and open-loop output linearization points at the "Measured Outputs" signal and "Manipulated variable" signal, as shown in : https://www.mathworks.com/help/slcontrol/ug/linearize-simulink-model.html
• Specify the operating tpoint at different time points that are indicative of standard operating conditions of the plant model using the "findop" function, as shown in : https://www.mathworks.com/help/slcontrol/ug/findop.html
• Linearize the model and ensure that linearization is not "ss(0,0,0,0)".
• Return to "MPC Designer". Navigate to "Simulink Operating Point" section, and use the newly obtained time point as your operating point, as shown in : https://www.mathworks.com/help/mpc/gs/designing-a-model-predictive-controller-for-a-simulink-plant.html

You may refer to the following MATLAB answer to know more about the error :

https://www.mathworks.com/matlabcentral/answers/1957259

Hope this helps.