ABSTRACT
A state equation is another variant of a transfer function, which still represents the system dynamics. The main distinction between transfer functions and state equations is that where a transfer function has only one input and one output, a state equation is capable of representing more than one input and more than one output. Where the controller specifications focus on only one output of the plant, transfer functions are used to design controllers using classical control theory. However, when the specifications involve a few outputs of the plant, the state space approach is more convenient. Hence, depending on the complexity of the problem, either the transfer function-based design or the state equation-based design is chosen. In modern
practice, whatever method is chosen, during the design of controllers, software tools such as MATLAB® are actively used (Cavallo et al. 1996).
