( z )
When designing compensators for real systems accommodations must be made for attributes of systems that don’t fit the paradigm of the control system design technique. It is often the case that the configuration of the real system is not compatible with the design technique. For instance, MIMO QFT design requires that the plant matrix, P(s) be square, that is, number of inputs must equal the number of outputs. Many real systems have more inputs than outputs,. For example, the inner loop of a flight control system (FCS) has three outputs [control roll rate (p), pitch rate (q), and yaw rate (r)] whereas many aircraft have more than three inputs, i.e. there are more than three control effectors.