With co-simulation, models from multiple simulation tools are coupled into a composite model and simulated together. This offers several advantages:
- The most suitable tool can be used for each part of the model
Most simulation tools are tailor-made for a certain kind of simulation. With co-simulation, each part of the composite model can be simulated using a tool specialized for that particular modelling domain.
- Co-operation is facilitated
Different simulation tools are popular in different organizations, departments or sectors. There is usually a large investment in existing models and trained staff. With co-simulation, all partners in a project can keep using their existing tools and hence preserve their investments.
- Improved modularity
It is often desirable to use different models for the same part of the system. A slow but detailed model can for example be replaced with a faster but simplified version depending on performance requirement. Co-simulation makes it possible to replace one sub-model while leaving the rest of the composite model unchanged.
- More accurate boundary conditions
Accurate boundary conditions, such as for example the load acting on a hydraulic piston, is often difficult to model in a single simulation tool. Co-simulation makes it possible to model this using a model from another simulation tool.
Numerically robust decoupling
A common issue with co-simulation is numerical stability. Decoupling a model into several sub-models induces time delays, which can cause numerical errors. One way to solve this is to introduce physically motivated time delays directly into the model equations. In this way, no numerical decoupling is required. This is the basic idea behind transmission line modeling (TLM).
Extensive compatibility
A co-simulation framework needs to support a wide range of tools. The best way to achieve this is to support open standardized interfaces such as the Functional Mock-up Interface (FMI). There is ongoing research in investigating and ensuring compatibility between TLM and FMI.
Multi-domain co-simulation
Effective co-simulation requires coupling of models from different domains, such as system simulation, multi-body mechanics and finite element models. It could also be of interest to couple time-driven and event-driven simulation tools.
Open Cyber-Physical System Model-Driven Certified Development
Cyber-physical systems put increasing demands on reliability, usability and flexibility while, at the same time, lead time and cost efficiency are essential for industry competitiveness. Tools and environments for model-based development of cyber-physical systems are becoming increasingly complex and critical for the industry: tool interoperability, vendor lock-ins, and tool life-cycle support are some of the challenges.
