Co-simulation Methods for EPAS and Chassis Systems Development
Examensarbete för masterexamen
Automation och mekatronik 300 hp (civilingenjör)
Co-simulation has become a trending topic of simulation techniques in the recent years with an emerging need for complex system development. However it can show inconsistent results compared with mono-simulation due to the drawbacks of modular integration. Many research works have been done on various types of co-simulation. The scope of this thesis is to have a fundamental understanding including stability and error analysis for parallel co-simulation with force/displacement coupling. In the thesis we have shown that the co-simulation error is dominated by the coupling error rather than error by numerical method. In addition the causality and interface selection have an important eﬀect on the robustness of co-simulation results, which can further implies to higher degree extrapolation and multi-subsystems. The study based on a basic dual mass-spring-damper research model can indicate how a complex system can be partitioned in a robust manner. Besides, a state-of-the-art co-simulation technique called nearly energy-preservingcoupling-element (NEPCE) has been referred and evaluated. The techniques is based on the concept of preserving energy in the power bond and use the residual energy as the error indicator. From the analytical and numerical results of the thesis it is shown that the concept has a limited usage in our research model. A new "causality-based extrapolation" method has been proposed based on the rough knowledge of the system and interface dynamics. It is more accurate than monolower-degree extrapolation and faster than mono-higher-degree extrapolation. In certain cases, the improvement can be almost as good as mono-higher-degree extrapolation. This discovery is extendable to multi-subsystems as well. Lastly the diﬀerent designs of interface and extrapolation methods have been tested on a cosimulation case study of high ﬁdelity electric power assisted steering(EPAS)model and chassis model.
Matematik , Mathematics