Derivative input is Inf

Hi,

I face a Simulink problem at the input of the integration block, which is:

Derivative input 1 of 'test_ahmed/Integrator' at time 0.003375 is Inf or NaN. Stopping simulation. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)

However,the input of the integration block is not infinity according the scope.

The model belongs to sliding mode control of biped robot in single support phase.

attached with the message simulink model..

Thank you!

Answer 1

[MUHAMMED FASIL]

Error with attached model.

1. Use 0.000000001 or so instead of 0 in Integrator initial condition box. Try reducing or increasing number of zeroes until your model runs fine.
2. Use a delay block in front of "division" block.

Otherwise send ur model to [e-mail]

[Ibrahim Seleem]

MUHAMMED FASIL Thanks for your answer. But I tried all of those solutions but the same problem occurred. I tried yesterday to send you email, but there was a problem occurred and email didn't be sent. So I'll attach the model and fuzzy functions here in zip file.

note: I'm using Matlab2012 I hope from you to help me.

[MUHAMMED FASIL]

Dear Ibrahim,

It ran without any error in my PC. Please try disabling algebraic loop error in diagnostic settings as shown in the attachment.

I hope u have also tried with variable step also and trying with ADAPTIVE algorithm

[Sofia Carvalho]

I have a similiar error, I guess: https://www.mathworks.com/matlabcentral/answers/334702-solar-pv-panel-simulink-solver-error