ABSTRACT
Design, development, modification, and control of an engineering system require an understanding and a suitable “representation” of the system; specifically, a “model” of the system is required. Any model is an idealization of the actual system. Properties established and results derived are associated with the model rather than the actual system, whereas the excitations are applied to and the output responses are measured from the actual system. This distinction is very important particularly in the context of the present treatment. An engineering system may consist of several different types of component; then, it is termed a multidomain (or mixed) system. Furthermore, it may contain multifunctional components; for example, a piezoelectric component which can function as both a sensor and an actuator. It is useful to use analogous procedures for modeling such components. Then the component models can be conveniently and systematically integrated to obtain the overall model. Analytical models may be developed for mechanical, electrical, fluid, and thermal systems in a rather analogous manner, because some clear analogies are present among these four types of systems. In view of the analogy, then, a unified approach may be adopted in the analysis, design, and control of engineering systems. Emphasized in this chapter are model types; the tasks of “understanding” and analytical representation (i.e., analytical modeling) of mechanical, electrical, fluid, and thermal systems; identification of lumped elements (inputs/sources, and equivalent capacitor, inductor, and resistor elements; considerations of the associated variables (e.g., through and across variables; state variables); and the development of state-space models and input-output (I/O) models.
