Simscape model using the pneumatics library doens't run anymore using Matlab Release 2016a

Hello everybody,

I am working on a simscape model using the pneumatics library. The model was built with R2015aSP1. Recently I have updated my Matlab version to the newest Release R2017a. There were not made any changes in the model but it doensn't run anymore. I get the following error: "Initial conditions solve failed to converge. ...Nonlinear solver to advance time one step failed to converge due to Linear Algebra error. Failed to solve using iteration matrix." To get further information I tried different Matlab releases and as of R2016a the model doensn't run anymore and I get error mentioned above. Are there any major changes from R2015b to R2016a? I couldn't find any indications in the release notes.

Best regards!

Andreas

Answer 1

[Steve Miller]

Hi Andreas,

There were significant improvements to the Simscape modeling and simulation engine in R2016a. These were not specific to the pneumatic library, and were listed as "Simulation Speed Improvements" in the R2016a release notes. In our vast suite of test models, which includes internally created examples and very large ones from industry, a number of models that previously did not run well simulated much more smoothly in R2016a.

If a model stops working in a given release, after looking at the release notes to see if we have changed anything, it is usually a good idea to try some of the following steps:

1. Verify the behavior of the simulation with a variable-step solver, which can adjust the step size to ensure accurate results and stable simulation.
2. For Simscape models, if the auto solver is selected, make sure it picks ode15s or ode23t
3. Reduce the maximum step size and lower the Relative and Absolute tolerances by a factor of 10 to see if it is simply numerical error causing the problem or if there is a problem with the physics.
4. Set the zero-crossing algorithm to Nonadaptive to make sure the solver does not ignore important zero crossings.

Thanks,

--Steve