ABSTRACT
Recently, there are also several approaches developed to solve tracking problems [64, 81, 82, 84, 123, 148, 149, 164]. The classical approach for LTI systems has been to design a closed-loop system that achieves the desired transfer function as close as possible [64]. The inherent shortcoming is over-design. Game theory [123] is most suitable to finite time control of time-varying systems. The linear quadratic (LQ) control theory method [82] requires a prior knowledge of dynamics of the reference signal. The H∞ optimal tracking solution [148] is suitable for cases where the tracking signal is measured online and it can hardly deal with the case where a prior knowledge on this signal is available or when it can be previewed. However, there are only a limited number of papers devoted to reliable or fault-tolerant tracking control problems. In order to realize the reliable tracking control in the presence of actuator faults, a method based on robust pole region assignment techniques [164] and a method based on iterative LMI [84, 149] have been proposed. The latter is a multi-objective optimization methodology, which is used to ensure the designed tracking controller guarantees the stability of the closed-loop system and optimal tracking performance during normal system and maintains an acceptable lower level of tracking performance in fault modes.
