This page contains the analyse of simulation error for the generated FMUs.
We will analyse the simulation error for the FMU PID controller. We design a system with a PID controller. On this diagram we have two generated FMUs (for Model Exchange and Co-Simulation) which have been generated from Xcos PID block. We will simulate with different solvers in order to compare the simulation results. The results of simulation of FMUs will be compared with the results of Xcos PID block.
In the following tables, we have the errors that were received after the comparison with the simulation results of Xcos PID block.
| Mean error | Standard deviation | Min | Max | Order | |
| Dormand-Prince | |||||
| FMU for Model Exchange | 0.0009646 | 0.0024503 | 0 | 1.1003015 | 1.0002757 |
| FMU for Co-Simulation | 0.0010303 | 0.0026149 | 0 | 1.1008595 | 1.0002744 |
| Runge-Kutta | |||||
| FMU for Model Exchange | 0.0006739 | 0.0017135 | 0 | 1.0977626 | 1.0002757 |
| FMU for Co-Simulation | 0.0027873 | 0.0070039 | 0 | 1.1169099 | 1.0002715 |
| Mean error | Standard deviation | Min | Max | Order | |
| LSodar | |||||
| FMU for Model Exchange | 0.0008094 | 0.0025042 | 0 | 1.0899767 | 1.0002757 |
| FMU for Co-Simulation | 0.0002562 | 0.0005055 | 0 | 1.0934054 | 1.0003286 |
| CVODE-BDF-NEWTON | |||||
| FMU for Model Exchange | 0.0038599 | 0.0099237 | 0 | 1.0808262 | 1.0013951 |
| FMU for Co-Simulation | 0.0004579 | 0.0010252 | 0 | 1.0954875 | 1.0002918 |
| CVODE-BDF-FUNCTIONAL | |||||
| FMU for Model Exchange | 0.0000025 | 0.0000030 | 3 | 1.0915449 | 1.0002757 |
| FMU for Co-Simulation | 0.0005118 | 0.0012158 | 0 | 1.0959081 | 1.0002919 |
| CVODE-ADAMS-NEWTON | |||||
| FMU for Model Exchange | 0.0034273 | 0.0089805 | 0 | 1.0834061 | 1.0023902 |
| FMU for Co-Simulation | 0.0004833 | 0.0010910 | 0 | 1.095673 | 1.0003073 |
| CVODE-ADAMS-FUNCTIONAL | |||||
| FMU for Model Exchange | 0.0000241 | 0.0000390 | 0 | 1.091729 | 1.0002757 |
| FMU for Co-Simulation | 0.0005477 | 0.0011522 | 0 | 1.0956803 | 1.0003743 |
On this page we compared the simulation results of generated FMUs. By analysing the results, we could say that the better solver for the FMUs ME is CVODE-BDF with FUNCTIONAL iterations. For the FMUs CS we have almost the same value of errors for all kind of solvers, this is explained by the fact that the FMUs for Co-Simulation have there own solvers to perform numerical integration. All of the above results was obtained with the simulation that has been done with default parameters for the relative and absolute tolerances. So, by configuring the parameters of the tolerance a user is able to reduce the simulation errors.