How it works
How it works
The software tools used provide extensive libraries with function blocks for the various physics: mechanics, hydraulics, thermodynamics, electrics, control, etc.. These function blocks are dragged and dropped to a sketch pane and get connected by the user, similar to electrical or hydraulic circuit diagrams. Therefore, in contrast to 3D simulations, where 3D CAD geometry is required as input, it’s often spoken as of 1D simulations. A very simple example is the step response of the mass-spring-damper system in the picture shown. After entering parameters, the software automatically derives the equations for the simulation from this graphic representation of the simulation model, meaning it compiles the code.
The content of these blocks, the underlying equations, can of course be adapted to the respective purpose or created from scratch. Compared to FEA and CFD, the calculation itself usually only requires relatively short time, the specific know-how respectively effort consists of the appropriate abstraction of the real product and gradual refinement of the model.
Our Simulation Capabilities
Many times objectives of the different areas compete. To find an overall optimum, all disciplines must therefore be integrated in a common model: mechanics, hydraulics, pneumatics, thermodynamics, electrics/ electronics, control and software. System simulation offers these capabilities.
In contrast to usually very time-consuming 3D simulations, which are therefore often static/ quasi-static (FEA) or steady-state (CFD), a very wide variety of time scales can be analyzed with system simulation. From milliseconds, minutes to whole days, depending on the physics. Since it is usually not necessary to solve as many equations for the lumped elements as it is for FEA or CFD, the solution process is much shorter.
Causal and Acausal Modeling
Acausal modeling is mainly used for physical systems, no defined inputs/ outputs are required. The advantage: the user get´s a clear plan of the entire system which can be understood very well. In causal modeling the function blocks require defined inputs/ outputs to enable a defined signal flow. Therefore it is mainly used in control engineering.
System simulation can be used in early development phases to find an optimal product architecture. No CAD geometry is required yet, definitions are made via parameters of a function block. The software packages used also offer applications for semi-automatic import of specific geometry parameters from a 3D CAD file.
Interfaces to 3D Simulation
Co-Simulation between system simulation und MBD/ FEA/ CFD, or via FMI/ FMU.
Testing of Control: MiL – SiL – HiL
- Model in the Loop: Testing of the controller model (e.g. in Simulink®) with the virtual, physical twin of the product (machine, vehicle, etc.). We do not use the term "Digital Twin" here, because from our point of view this would include control already and many other aspects like CAD geometry, manufacturing data, etc..
- Software in the Loop: Testing of the compiled controller code with the virtual, physical twin of the product.
- Hardware in the Loop: Testing of the controller hardware (ECU, PLC, etc.) with the flashed code and the virtual, physical twin of the product (realtime-simulations).
Due to short solve time, many variants can be validated virtually.
Intellectual Property Protection
Models can be encrypted, passed on to customers and suppliers without publishing the IP. For example, the model of a machine can be passed as a black box, only with definitions of inputs & outputs, to a controller supplier so that they can optimize the controller. Experience shows that it is much more efficient to work with a model than to rely solely on text-based specifications.