Using Simulink As A Design Tool

SIMULINK is a graphical user interface (GUI) to MATLAB for solving ordinary differential equations (ODE’s). It is normally used as an analytical tool but may also be used as a design tool. This paper describes how to use SIMULINK from within the MATLAB environment to determine a target value for a design variable. This technique is applicable for use in a design course or in a numerical methods course, as well as for engineering practitioners. Building a model in SIMULINK may be accomplished by following a process consisting of four distinct stages. These stages are model development, model definition, model analysis, and model verification. Model development consists of developing a mathematical equation that describes in some manner a physical phenomenon. Model definition consists of building the model in SIMULINK. Model analysis consists of running the program to get a solution. Model verification consists of making the assessment of whether the answer from the computer is right or wrong. This paper describes how to use this process to create a dynamic simulation of a falling skydiver. Once the designer has a model describing the behavior of the system, it is often necessary to determine engineering targets for various parameters of the design. Designers frequently need to make trade-offs among competing design parameters affecting system performance. Thus, the designer must have a tool to predict how changing a particular design parameter will change system behavior. This paper concludes with a description of how to determine the optimum value of drag coefficient for the deployed parachute for the simple skydiver model in the case where we cannot solve for the design variable directly.