Non-fragile robust control for a class of system with unknown uncertainty

The non-fragile robust control design is discussed for the controlled plant and the controller with unknown uncertainty and different from other robust control methods were given, that is, the system can tolerate the greatest uncertainty on the basis of the guaranteed certain performance. Based on the meeting certain bandwidth and overshoot, a non-fragile robust performance design method is presented, it allows the system to tolerate the greatest uncertainty extent of the closed loop with the unknown uncertainty. It is also suggested that the design of the non-fragile robust performance can be formulated as a mu-synthesis problem. The selections of the weighting functions for a class of system with unknown uncertainty are studied and the mu-synthesis non-fragile robust PI controller is solved. The simulation results show that the proposed method is valid.