I am using the Fuzzy Controller in MatLab R2017a. But when I execute the controller, it gives an error:
Error in 'model3_FUZZY/Fuzzy_PID_Controller/FuzzyController': Initialization commands cannot be evaluated.
Caused by:
Struct contents reference from a non-struct array object.
The files are also given. Kindly guide me, How do I proceed, and remove this error.
Hi Tariq Sm ,
There is nothing wrong with the files. No simulation error message. Here are results, which I compared your original fuzzy system with the proportional control (Kp = 1). Strictly speaking, the so-called fuzzy PID controller does not contain the integral or derivative terms.
Your fuzzy control law is:
u = [5 + Fp(e)] + [0.25 + Fi(e)] + [1 + Fd(e)]
where all outputs of the fuzzy system are the functions of the error signal.
The reason your fuzzy controller cannot stabilize the 3rd-order system is because on each control term you added the destabilizing external energy {5, 0.25, 1}. If you remove them, the system will be stable.
Hi Tariq Sm,
You got the error because you didn't place the *fis file in the same directory where the *slx file is. So, put both files in the same folder will remove the error message. Even if you fix the error, the structure of your fuzzy PID controller is still improper.
If both files are already in the same folder, then the error must be due to the incorrect search path used by MATLAB to locate the FIS file. The folder that contains both files must be on the search path.
You need to correct the file locations (fuzzy fix file, etc.) regarding the specific operating file which is giving error.
Hi Majid Moradi zirkohi ,
Tariq Sm already uploaded his simulation files on this thread. Please scroll up. More importantly, the problem lies in the design of the fuzzy controller. Although Tariq Sm claimed that he followed the design that was published in the paper, the design of the fuzzy PID controller is incorrect.
As you can see, the control law in Tariq's design looks like this:
utariq = [5 + Fp(e)] + [0.25 + Fi(e)] + [1 + Fd(e)].
It is a single-input, mutiple-output (SIMO) fuzzy system. From the control theory perspective, it works similarly like a nonlinear proportional controller kp1·e + kp2·e + kp3·e + constant(5 + 0.25 + 1).
The integral term ki·∫e and the derivative term kd·e' are excluded in his design.
im also facing the same problem,
Error in 'program2model2/Fuzzy Logic Controller1': Initialization commands cannot be evaluated.
Caused by:
- Reference to a cleared variable fis.
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