Bond Graph Modeling Techniques Thtsim, Software for The Simulation of Continuous Dynamic Systems on Small And Very Small Computer Systems

Abstract

From our own investigations it is seen as a trend to use small and low-cost computer systems for the interactive simulation of small and medium size continuous dynamic syetems. Such simulation systems can be used where previously an an logue computer had been applied, as a greater range of flexibility is available. The LSI-II from DIGITAL with a dual floppy disc and graphical outputs has been chosen to build a powerful simulation system. THTSIM is a software package that can be used in this system and that offers som usefull extensions, in addition to the normal facilities of a “hands-on” interactive block diagram orientated simulation language. THTSIM also accepts a bond graph as a model input, and stored data from previous simulation runs or from real processes can be used. Frequency analysis is possible by means of an FFT algorithm. To create multi-run facilities, for example for parameter estimation, the main functions of the program are also FORTRAN callable. TBTSIM is written in PDP-II assembler language, and by means of conditional assemblies a load module can be generated for either a stand-alone processor without mass-storage or for systems based on the RT-II or RSX-II operating system. A FORTRAN version is available too. Planned developments for the near future are discussed, including the use of p rsonal computers with acceptable graphics and calculation performance and the use of the PASCAL language.