Models

Abstract

System analytical models are given in the form of equations. Linear models are represented by linear differential equations. Structural models are represented in the form of second-order differential equations or in the form of first-order differential equations as a state-space representation. In the first case, the system dynamics is typically represented by the system degrees of freedom, and in the second case by the system states. Preferred by structural engineers, second-order differential equations of structural dynamics have a series of nice mathematical and physical properties. In this representation of a long tradition many important results have been derived. The state-space model is a standard model used by control engineers. Most linear control system analysis and design methods are given in state-space form. In this chapter we use both: second-order and state-space models.