Enforcing the Positive-real or the Negative-imaginary Property in a Linear Model

This chapter deals with the problem of enforcing either the positive-real or the negative-imaginary property in a linear model through a forward action. Given a linear model, which is for example not positive-real, it is shown how to design a forward action able to make the system passive. In an analogous way, it is discussed how to design a forward action to make a system negative-imaginary. Matlab problems are included.