ZHANG Xiu-Yu Received his bachelor and master degrees from North China Electric Power University in 2003 and 2006, respectively. He is currently a Ph.D. candidate at the School of Automation, Beijing University of Aeronautics and Astronautics. His research interest covers robust control and adaptive control. E-mail: zhangxiuyu80@ 163.com LIN Van Professor at the School of Automation, Beijing University of Aeronautics and Astronautics. His research interest covers robust control and adaptive control. Corresponding author of this paper. E-mail: linyanee2@yahoo.com.cn