Simulink and Simscape models built in 2021a do not work properly in 2021b

I built a bipedal robot locomotion control model using Simulink and Simscape in 2021a. When I ran this model in 2021b, the results were so far off from 2021a that it didn't work properly. I tried checking with the model upgrade tool and got the following prompt:

However, in both 2021a and 2021b, the solver automatically selects the ode45 method. I haven't used the ode23t method, I tried updating and it still didn't work, so I can't understand the prompt.

Also, I found that the model runs a lot faster in 2021b, but the results are not the same as in 2021a. So I suspect the solver has changed. How can I fix this so that I get the same simulation results in 2021b as in 2021a?

Answer 1

[Tom Vose]

Hi Jingchao. It's hard to know what's going on without seeing the model. If possible, I'd suggest that you submit the model and repro steps to technical support so someone can take a look.