Songyin Cao was born in 1982. He received the B.S. degree in 2003 in Yangzhou University. He is now a Ph.D. candidate at School of Automation in Southeast University. His research interests include fault detection and diagnosis, antidisturbance estimation, and initial alignment. E-mail: cao_songyin @ yahoo.com.cn Corresponding author,Lei Guo was born in 1966. He received the Ph.D. degree in control engineering from Southeast University, Nanjing, in 1997. He is now a professor at School of Instrumentation and Opto-Electronics Engineering, Beihang University, Beijing. His research interests include robust control, stochastic systems, fault detection, filter design, and nonlinear control with their applications.E-mail: lguo @buaa.edu.cn Xinyu Wen was born in 1977. He is a lecturer at Department of Automation in Taiyuan University of Science and Technology, and doctor candidate at School of Automation in Southeast University. His research interests include antidisturbance control and intelligent control. E-mail:wxysunrain@ 163.com