A control design for nonlinear systems using the properties of minimum phase systems

It is known that mechanical systems are generally nonlinear systems. A control design for nonlinear systems has attracted attention over the years, and a lot of design methods have been reported so far. One of such methods is flatness theory, which seems to be a powerful tool in nonlinear designs. However, it is difficult to find the flat output needed for the linearization of nonlinear systems. In this paper, we introduce a new idea of the so-called minimum phase output. And, we propose control design methods using the minimum phase output.