Numerical Simulation of the Fluid Control Systems by AMESim

Michel Lebrun
University Claude Bernard, Lyon
Daniela Vasiliu, Nicolae Vasiliu
University Politehnica of Bucharest

Abstract: Many different modeling and simulation software packages were created to perform studies in the fields of automobile, aerospace, robotics, offshore and general hydraulics engineering but none offered the full range of capabilities needed. There were deficiencies in the numerical capabilities, in the graphical interface and in the general modeling concept. The AMESim package was developed to overcome these limitations. This paper gives a description of the technical features, which were central objectives in the design of the software, and some examples of typical applications. A large amount of experience has been accumulated through more than 400 consultancy projects between the IMAGINE company, which created the software, and strong industrial companies.

Keywords: Modelling and Simulation Software, Fluid Control Systems, Electro Hydraulic Servo Systems

Michel Lebrun graduated Applyied Mechanics in INSA Lyon in 1970 and became Ph.D. in 1978 in the same institute, obtaining the diploma of "The Best State PhD Thesis". In 1986 he obtained the title of State Doctor and founded SOCIETE IMAGINE, a research company devoted to the fluid control systems. The company developed the most powerful software for modeling and simulation the dynamics of the engineering systems - AMESim - used by all the innovative companies all over the world. In 1990 Michel Lebrun awarded the GOLD MEDAL of the FRENCH DEVELOPMENT INDUSTRIAL SOCIETY. The main fields of activities were: the development of the Bond Graph theory as a tool for physical modeling of the technical systems; modeling and simulation of the automotive components and systems.

Vasiliu Daniela graduated in Mechanichal Engineering from "Politechnica" University of Bucharest in 1981. He became a Ph.D. in Fluid Control Systems in 1997 at the same university, after a research stage at INSA Toulouse. From 2001 she is state professor in the "Politechnica" University of Bucharest, as head of the CAD/CAE Laboratory from Power Engineering Faculty. She worked also for the industry, as project engineer in the National Turbomachinery Institute from Bucharest. In 1994 he joint INSA Toulouse as associated research professor, and SOCIETE IMAGINE from France, as associated researcher. She is also working as a scientific advisor for IT in the Romanian Environmental Engineering Institute. She is working mainly in modelling, simulation and dynamic identification of the electrohydraulic control systems.

Nicolae Vasiliu graduated in Hydropower Engineering from Politechnica University of Bucharest in 1969 as a lider of the promotion. He became a Ph.D. in Fluid Mechanics at the same university, after a research stage in Von KARMAN Institute and Gand State University. He is state professor in the Polytechnical University of Bucharest from 1994, as the head of the Fluid Control Laboratory from Power Department. He worked always for the industry, as project manager or scientific advisor. In 1980 he joint the Hydraulic Control Team from the Romanian Aerospace Institute. In 1994 he joint INSA Toulouse as associated professor, and SOCIETE IMAGINE from France, as scientific researcher. He is the general director of the Romanian Innovation Agency, and he is representing Romania in FPNI. He is working mainly in modelling, simulation and dynamic identification of the electrohydraulic control systems.

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CITE THIS PAPER AS:
Michel Lebrun, Daniela Vasiliu, Nicolae Vasiliu, Numerical Simulation of the Fluid Control Systems by AMESim, Studies in Informatics and Control, ISSN 1220-1766, vol. 18 (2), pp. 111-118, 2009.

1. Need of the Multiport Approach in System Modeling and Simulation

In the signal port approach, a single value or an array of values are transferred from one component block to another in a single direction. This is fine when the physical engineering system behaves in the same way such as with a control system. However, problems arise when power is transmitted. This is because modeling of components that transmit power leads to a requirement to exchange information between components in both directions. In order to use a signal port approach in this situation, two connections must be made between the components where physically there is only one. This leads to a great complexity of connections and means that even very simple models involving power transmission appear complex and unnatural.

In contrast to the signal port approach, with the multiport approach, a connection between two components allows information to flow in both directions. This makes the system diagram much closer to the physical system. Normally there are two values involved and the theory of bond graphs provides a good theoretical background into the relationship between these values and the power transmitted. However, there is no limitation in the number of quantities involved. There may be one quantity or three or more quantities. When there is only one quantity, the situation is just like with signal ports. Thus, signal ports can be regarded as a special case of multiports.

AMESim has always used the multiport approach and Figure 1 shows part of a simple electro hydraulic system using multiport block diagrams. Figure 2 shows the same system with signal ports. The control for the valve is identical in both cases since for this port, the multiport reduces to a signal port. However, for the hydraulic and mechanical ports, the extra connections needed for the signal port approach are apparent.



Figure 1. The multiport approach

Figure 2. The signal port approach

6. Conclusion

The main aim of the AMESim is "To create Good Models without Writing a Single Line of Code" (Lebrun and Claude, 1997). An important prerequisite of the basic element library is the creation of extremely well tested, reliable and reusable submodels that a user can employ with complete confidence (IMAGINE, 2005). The writer of the basic element library must be competent in all the modeling skills. However, the user of the basic element library is relieved of the need to write code and formulate the mathematics. Understanding of the details of the physics is not needed but decision on assumption is necessary which imply some knowledge of physics. Understanding of the engineering system and an ability to interpret results is still important. Experience in training design office staff to use of the basic element library suggests that it is learnt very rapidly. The possibility of quick high level technical developments as ABS, EBS, common rail multipoint injection systems, electro hydraulic automatic transmissions, self tuning hydraulic and pneumatic suspensions, hydraulic power steering, fly-by-wire systems and many others (Mare and Cregut, 2001; Lebrun, 2004). Companies like AEROSPATIALE, MATRA, BOSCH, FERRARI, DAIMLER-CRIYSLER, GENERAL MOTORS, etc. are currently using this modeling and simulation software for future developments.

Academic training programs are now developed in different countries, including Romania, for teaching the software in the terminal years (Vasiliu and Vasiliu, 2005), and for applied researches (Vasiliu, et al., 2003).

References

  1. IMAGINE SA (2005), Advanced Modeling and Simulation Environ-ment, Release 4.2.1. User Manual, Roanne.
  2. Lebrun, M., Claude, R. (1997), How to create Good Models without Writing a Single Line of Code, Fifth Scandinavian International Conference on Fluid Power, Linköping.
  3. Lebrun, M. (2004), EHA's Model Reduction Using Activity Indexes. Recent Advances in Aerospace Hydraulics, INSA Toulouse.
  4. Mare, J.C., Cregut, S. (2001), Electro Hydraulic Force Generator for the Certification of a Thrust Vector Actuator, Recent Advances in Aerospace Hydraulics, INSA Toulouse.
  5. Vasiliu, N., Călinoiu, C., Vasiliu, D., Ofrim, D., Manea, F. (2003). Theoretical and Experimental Researches On A New Type Of Digital Electro Hydraulic Speed Governor For Hydraulic Turbines, 1st International Conference on Computational Methods in Fluid Power Technology, Melbourne.
  6. Vasiliu, N., Vasiliu, D. (2004). Electro Hydraulic Servomechanisms with Two Stages DDV for Heavy Load Simulators Controlled by ADWIN, Recent Advances in Aerospace Hydraulics, INSA Toulouse.
  7. Vasiliu, N., Vasiliu, D. (2005). Fluid Power Systems, Vol.I. Technical Publishing House, Bucharest.