Development of a real-time simulation environment

A systematic approach to real-time simulation of multibody systems requires a versatile real-time simulation environment. Such an environment includes, besides the numerical solver core of the mechanism dynamics, a graphics engine, and, in many cases, a physical visualization environment. The use of real-time simulation in human-in-the-loop-simulation (HIL) sets requirements for the flexible connection of the operator to the dynamics model. A visual preprocessor can be used for reducing modeling errors and for rationalizing model building by utilizing different preprogrammed components. An effective preprocessor should also offer a possibility to connect basic operator controls to the simulation model as well as enable the description of the virtual world. This paper focuses on the description of the real-time multibody simulation environment developed in Lappeenranta University of Technology. The simulation software environment consists of several function libraries in order to achieve an extendable and modular program structure. The core of the system is the dynamic solver module which is initialized using XML-based input files processed in the parser module. The graphics engine includes the visualization of the virtual world and a Graphical User Interface (GUI) for controlling the environment. A networking library is used to connect the graphics engine to the solver core via a client-server interface and allows distribution of the environment across multiple computers. In conclusion, the modeling stages and definition of the control interfaces are illustrated with the gantry crane model.