4Bonchis A, Corke P I, Rye D C, et al. Variable structure methods in hydraulic servo systems control [J]. Automatica, 2001,37: 589-595.
5Kalyoncu M, Haydim M. Mathematical modeling and fuzzy logic based position control of an electro hydraulic servo system with internal leakage[J]. Mechatronics, 2009,19(6): 847-858.