In the last two chapters, the decoupling control problem was discussed in detail. In the two decoupling control schemes, the MIMO system was decomposed into a series of independent SISO loops. Optimal design procedures were developed and analytical controllers were obtained. The common feature of the two methods is that the closed-loop response is decoupled and thus the response of each channel is determined by only one parameter. This is important for applications, since when a channel is tuned, it is usually desirable that other channels not be affected. Furthermore, this feature makes the tuning of decoupling control systems be simplified significantly.