4Burton J A,Zinober S I. Continuous approximations of variable structure control [J]. Int J SYS SCI ,1986,17 (6) : 252- 259.
5Hwang G C, Chang S. A stability approach to fuzzy control design for nonlinear system[J]. Fuzzy Sets and Systems, 1992,48 : 279 - 287.
6Sinn C L, Yung Y C. Design of self-learning fuzzy sliding mode controllers based on genetic algorithms[J]. Fuzzy Sets and Systems, 1997,86 : 139- 153.
7Bartoszewicz A. Discrete-time quasi-sliding mode control strategies[J]. IEEE Trans on Ind Electron ,1998,45(4):633-637.
8Gao W B,Wang Y F,Homaifa A. Discrete-time variable structure control systems[J]. IEEE Trans on Ind Electr, 1995,42(2) : 117- 122.
9Katsuhisa Furuta,Pan Y D. Variable structure control with sliding sector [J]. Automatica, 2000,36 : 211 - 228.
10Xu J, Lee T,Wang M. Design of variable structure controllers with continuous switching control[J]. Int J Contr , 1996,65(3) : 409- 431.
4Bartoszewicz A. Time-varying sliding modes for second-order system[ J]. IEEE Proc. Control Theory Application, 1996, 143 (5) :455 - 462.
5Choi S B, et al. A timevarying sliding surface for fast and robust tracing control of 3 second-order uncertain systems [J]. Automatica, 1994, 30(5): 809-904.
9Wang Xuyong, Li Wanyu, Fu Yongling, et al. Investigation into Mechanism of Low Speed in Electro-hydraulic Position Servomotor System. New Achievement in Fluid Power Engi- neering [ C]. Hangzhou, Beijing,1993:147 - 150.
10Canudas De Wit C, Noel P, Brogliato B. Adaptive Friction Compensation in Robot Manipulators : Low-Velocities [ J ]. In- ternational Journal of Robotics Research, 1993,10 ( 3 ) : 189 - 199.
