This is a great opportunity to express my sincere gratitude to all who have supported me during the completion of this thesis. First and foremost, I am heartily thankful to my supervisor, Professor Changyun Wen, for his constant guidance and inspirational encouragement. This thesis would not have been possible without his knowledge and valuable advices. I am also grateful to him for his genuine concern about my well-being and future plans. I am specially grateful to Dr. Jing Zhou for her generous support which is highly beneficial to the related research. Some of her bright thoughts are very helpful in shaping up my ideas. I would also like to extend my appreciation to Professor Guang-Hong Yang for his useful discussion about actuator redundancy. Appreciation continues to Professor Gang Tao for his constructive comments in improving the quality of this thesis, to Processors Romeo Ortega and David John Hill for their advisory comments and encouragement. Furthermore, it is a great pleasure to thank my colleagues, Guoqi Li, Yan Chen and Jiangshuai Huang, for hours of productive discussions. I would like to convey special acknowledgement to my close friends, Yue Tian, Jianglei Qin, Xi Wang, Ling Huang and Zhaolei Wang. I am extraordinarily fortunate to have them always by my side, giving me faith, sharing my joy and bitterness.