1. Liu Chang-nian. Optimized design theory of hydraulic servo system [M]. Beijing: Metallurgical Industry Press, 1989: 155 (in Chinese).
2. Wu Zhen-shun, Zhang Li-chun, Zhao Chun-lei. Adaptive controller and its application in force system of asymmetric cylinder controlled by symmetric valve [J]. Chinese Journal of Mechanical Engineering, 2007, 20(6): 50–53.
3. Pi Yang-jun, Wang Xuan-yin. Observer-based cascade control of a 6-DOF parallel hydraulic manipulator in joint space coordinate [J]. Mechatronics, 2010, 20(6): 648–655.
4. Zhao Ji-yun, Chai Guang-yuan, Li Chang-xi. Theoretical study of the characteristic of an asymmetric hydraulic cylinder controlled by an asymmetric valve [J]. Journal of China University of Mining & Technology, 1996, 25(4): 22–27 (in Chinese).
5. Liu Rong, Wang Xuan-yin, Wu Gen-mao. Dynamic characteristics study on asymmetric hydraulic cylinder controlled by GPCM valve [J]. China Mechanical Engineering, 2004, 15(2): 154–154 (in Chinese).