6.1 Introduction

The previous chapters discussed techniques for building simulations of dynamic systems, and covered topics such as the development of mathematical models of system components and the selection and use of numerical integration algorithms. This chapter assumes that development is complete and that an executable simulation is available for use. You can now define test scenarios and execute them. Each scenario simulates the behavior of the system under a specific set of conditions. The specification for a scenario consists of the initial conditions of the system and environment as well as any input signals that vary over time.

When setting up a simulation scenario, we must identify which variables to save during execution for later analysis. This output data must contain information sufficient to make judgments about the behavior of the simulation and of the system being simulated, and enough information must be collected to answer as many reasonable questions as possible about the performance of the simulated system, but not so much to overload the capabilities of the data storage devices and analysis tools. This requires some care in the selection of what information to collect and how frequently to save samples of time-varying values.

The data saved during simulation execution falls into three general categories:

Initial conditions These values define the starting conditions. Initial conditions are required for states in differential and difference equations. In addition, a number of parameter values are usually necessary to determine the initial condition of the system and its environment. Ideally,...