An error occurred while running the simulation and the simulation was terminated

Hi everyone, I am using matlab simmulink to simulate the system. However, I am having the following problem:

An error occurred while running the simulation and the simulation was terminated

Caused by:

• Domain error. To compute complex results, make at least one input complex, e.g. 'power(complex(a),b)'.

Answer 1

[Walter Roberson]

You have a MATLAB Function block in the lower left. It has s0 as input and ds0 as output. The 4th line of code for it is

ds0=(s0.^(q0/p0));

where q0/p0 does NOT happen to be an integer.

That code has problems when s0 is negative. Negative raised to a fractional power gives a complex result, but you have not specifically marked the inputs as being complex.

In practice, s0 does go negative.

You could try

ds0=(complex(s0).^(q0/p0));

and that will remove the error about complexity. However you will then get errors about how the complexity of ds0 does not match the back-propagated complexity of the signal. It is doubtful that your Position Tracking Controller is prepared to handle complex input.

[The Tran]

Thanks for your help. I am converting the file from S-function to matlab-function. However, the above error occurred because I am simulating the kinematic equations in the document. Can you help me check?

[Walter Roberson]

The file chap7_3plant.m uses

    T1=abs(x1)^(q/p)*sign(x1);
    T2=abs(x1)^(q/p-1)*sign(x1);
%...
    T1=abs(x2)^(p/q)*sign(x2);
    T2=abs(x2)^(2-p/q)*sign(x2);

Notice the abs(). Your implementation for ds0 has s0.^(q0/p0) without the abs()