IDGREYMODEL - Too many inputs - but only one input - Help please

Hi,

I am trying to make a grey box model for my thermal network of a zone. I get the error

Error using idgrey (line 372)

The ODE function "Thermalzone" could not be evaluated successfully using the given set of parameters, sample time and optional arguments.

The error message generated during the evaluation was:

Too many input arguments.

Error in graamodell (line 7)

sys = idgrey(odefun,parameters,fcn_type);

However Ionly have one Input. I cant see how this is happening.

The code I have made is here:

%For the ODE function thermal zone
function [A,B,C,D] = Thermalzone(R1C1)
A=-1/(R1C1);
B=transpose([1/(R1C1), 1/(R1C1), 1/(R1C1), 1/(R1C1)]);
C=1;
D=transpose([0 0 0 0]);
end
%For the ID grey model
odefun = 'Thermalzone';
R1C1=0.3*0.4;
parameters={'R1C1', R1C1;};

fcn_type = 'c';

sys = idgrey(odefun,parameters,fcn_type);

Answer 1

[Jalaj Gambhir]

Hi,

The first issue is the missing Ts parameter. The value of Ts parameter is set based on the value of ‘fcnType’ (if not provided inside idgrey). Have a look here. But solving this issue alone does not solve the problem.

The next issue is the usage of transpose in the variables ‘B’ and ‘D’. The sizes for the terms should be consistent while solving the ODE. The matrix shape expected are mentioned here. The correct function definition:

%For the ODE function thermal zone 
function [A, B, C, D] = Thermalzone(R1C1,Ts) 
A= -1/(R1C1); 
B= [1/(R1C1), 1/(R1C1), 1/(R1C1), 1/(R1C1)]; 
C= 1; 
D= [0 0 0 0]; 
end

%For the ID grey model 
odefun = 'Thermalzone'; 
R1C1=0.3*0.4; 
parameters={'R1C1', R1C1}; 
fcn_type = 'c'; 
sys = idgrey(odefun,parameters,fcn_type); 

[Lara Hammer]

Thank YOU! It worked!