A Contribution for Virtual Prototyping of Mechatronic Systems Based on Real-Time Distributed High Level Architecture
Summary (3 min read)
- A mechatronic system is the combination of several components from different domains (mechanics, automatic control, electronics, and embedded control software).
- Their design can be difficult and the development period of such complex systems has to be as short as possible.
- Many methods are used for coupling of dynamic simulations.
- The authors present a method based on the high level architecture (HLA) to make communication possible between the 3D OpenMASK (Modular Animation and Simulation Kit) virtual prototyping simulator  and the MULTIPHYSICS OpenModelica  simulator.
- HLA is situated in continuation of the works on cosimulation with respect to disclosing proprietary information about the subsystem models by introducing a standardized layer to exchange data without requiring an integrator environment .
2 Modeling and Simulation for Mechatronics in a Distributed Architecture
- It consists of electronic, automatic, and computer technologies.
- Accordingly, the behavior of these systems with various technologies is difficult to model.
- Behaviors of the control part and the operative part are modeled by different hybrid automata, which can be coupled jointly following the method provided in Ref. .
- In the HLA terminology, the authors mean by the term “federate,” each elementary simulator, and by the term “federation” a group of intereffective federates.
- The authors identified two federates: one federate for the animation of 3D objects and one behavioral federate, which represents the control and operative parts of the mechatronic system (Fig. 1).
- HLA is defined under the IEEE standard 1516 for the architecture of interoperable distributed simulations.
- The HLA is described by some specifications composed of: — a series of rules that specifies the responsibilities of the federates and the federation — an object model template — specifications concerning the application programming interface (API).
- There are few applications to integrate HLA in commercial and academic simulators.
- HLA functions are not planned to integrate nonmilitary simulators.
- In the field of virtual prototyping, the authors found an approach presented in Ref.  to link the oRis platform with the RTI.
- OpenMASK is an open source platform for modular applications development and execution in animation, simulation, and virtual reality fields.
- An OpenMASK module can also contain inputs=outputs for the exchange of data.
- OpenMASK modules can exchange events directly or by means of the OpenMASK’s bus.
- Its goal is to model complex physical systems including electric, mechanical, hydraulic, and thermal components .
- OpenModelica is a free environment of modeling, compilation, and simulation, based on a BSD (Berkeley Software Distribution) license.
- The C code generated is combined with a library of useful functions, a run-time library and a digital solver differential algebraic equations.
- The default integration method for OpenModelica is the DASSL code as defined by Brenan et al. .
- In order to integrate event handling in the compiler and run-time system, the front-end must produce crossing functions and handlers for the events; the actual search for zero crossings is left to the solver .
6 Integration of HLA Services in Simulators
- Given that the authors are only interested in the dynamic state variables, they describe every mechanical component by an HLA object.
- During the simulation, the OpenModelica federate updates its HLA object attributes by calling the publish service or by sending interaction.
- When a connection request is received, a connection is established and the wrapper can receive the data from the simulation under OpenModelica.
- The second part catches messages and updates from RTI using callbacks functions declared in the class FederateAmbassador.
- After that, the federate requests to synchronize its execution with other federates.
7 Synchronization and Real-Time Management
- 1 Simulators Synchronization at the Beginning of the Simulation.
- Also, at each step, the federate can send interactions and receive data from other federates.
- The HLA time management coordinates the advance of logical time among all federates in a federation.
- In the next part, the authors present a module to make OpenModelica execution real time.
- The progression of simulation time during the execution of a simulation may have or not a relationship with the progression of wallclock time.
- After the integration of the HLA services in both simulators, the authors applied their global approach to a mechatronic system.
- The authors chose a simple but significant example.
- The linear drive is controlled by a controller module which delivers the dc motor supply voltage according to the position x of the linear drive.
- The authors instantiated the RealTime module and inserted it in the global model to synchronize the time execution with the wallclock time.
- Once the OpenModelica simulation starts, variables are communicated to OpenMASK via the RTI to animate the 3D objects.
- In the case of large models, efficiency problems can arise.
- Another aspect is to make the simulation more reactive referring to events.
- The authors have not yet addressed this aspect.
- The second way is linked to the accuracy in the case of bidirectional communication where events from OpenMASK serve as inputs for OpenModelica.
- Instead of using TIME ADVANCE REQUEST, as does a time-stepped federate, the event-driven federate uses NEXT EVENT REQUEST to request an advance of its clock.
- The authors presented an open source approach for modeling and simulating mechatronic systems based on the HLA.
- To make the global simulation real-time, the authors proposed an approach based on real-time techniques and HLA time management services.
- All open source modules developed are available in their laboratory and will be officially registered on the Modelica site.
- The authors plan to manage events taken into account by OpenMASK and benefits from its interactive feature.
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Cites background from "A Contribution for Virtual Prototyp..."
...In , the authors encode a connection between HLA and Modelica  for the virtual prototyping of mechatronic systems....
"A Contribution for Virtual Prototyp..." refers background or methods in this paper
...the time-stepped pattern, another typical pattern of time management is the event-driven pattern ....
...With the real-time simulations, a mapping function to translate wallclock time to simulation time can be used ....
...The simplest approach to manage logical time in a simulation is to advance time in equal steps ....
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Frequently Asked Questions (2)
Q1. What contributions have the authors mentioned in the paper "A contribution for virtual prototyping of mechatronic systems based on real-time distributed high level architecture" ?
In this paper, the authors present an open source approach for modeling and simulating mechatronic systems based on the high level architecture ( HLA ).
Q2. What future works have the authors mentioned in the paper "A contribution for virtual prototyping of mechatronic systems based on real-time distributed high level architecture" ?
In the future work, the authors will treat the extension presented especially in Sec. 9. The authors plan to manage events taken into account by OpenMASK and benefits from its interactive feature.