Solving Matrix Equation in Simulink

2014 1 13
1 个回答
更新时间：2014 2 2
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Hi everyone, I have the following matrix euation:
Pdot=beta*P-P*(Phi*Phi'-error*H)*P
which P is a matrix with 4*4 size. I want to solve this equation in simulink.I use matlab embeded block.In every step,this equation should be solved and P is updated. what code i should write?

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回答（1 个）

Mischa Kim
Mischa Kim 2014-1-13

1 个投票

The basic structure looks like this:
In the embedded function you compute Pdot which is inputted into an integrator that computes P. Don't forget to set initial conditions for P by opening the integrator. Assuming that all the other variables are constants the embedded function might look something like:
function Pdot = fcn(P)
beta = ...
Phi = ...
Phip = ...
error = ...
H = ...
Pdot = beta*P - P*(Phi*Phip - error*H)*P;

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Sarah Miller
Sarah Miller 2014-2-1
Thanks Mischa,
I tried it,but it is sensitive to initial condition,and this error was ocurred:
Derivative input 1 of 'onlineident2/Integrator' at time 48.42 is Inf or NaN. Stopping simulation. There may be a singularity in the solution. Would you pls what can i do?
Mischa Kim
Mischa Kim 2014-2-1
Hard to say. Can you attach the model (see paper clip)?
What happens when you change integrator settings (in > Simulation > Model Configuration Parameters)? Decrease RelTol and AbsTol to say 1e-10 .
Sarah Miller
Sarah Miller 2014-2-2
I cant attach the model,Where is the paper clip?
Mischa Kim
Mischa Kim 2014-2-2
When you have a comment text box open, the paper clip is right on top of the window on the right, next to the Help button.
Sarah Miller
Sarah Miller 2014-2-2
Yeah,you are right.onlineident2.mdl was attached. In fact,I want to solve 2 following matrix equation:
Pdot=beta*P-P*(Phi*Phi'-error*dP)*P
tetaDot= P*error*Phi
The size of teta is 4*1 and size of P is 4*4. If Initial Condition of teta is chosen like the following:
[0.2-1.625 0.01-0.625 0.5 40]'
no error was happened,but actually teta equation wasnt solved.
it is sensitive to initial condition,and this error was ocurred:
Derivative input 1 of 'onlineident2/Integrator' at time 48.42 is Inf or NaN. Stopping simulation. There may be a singularity in the solution. Would you pls what can i do?
Would you pls tell me, how can i cope with it?

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