Abstract: Because of high nonlinear feature of the platform driven by electro-hydraulic actuators and the serious load coupling among actuators, the fidelity and smoothness of simulator are impacted. The driven branch of the platform was as control object in the platform controller design in the past and neglect-ing the influence caused by load-coupling among actuators, which resulted in declining of the platform control precision, even unsteadiness. For the above reasons, taking the platform as a control object in the controller design, a nonlinear adaptive control algorithm based on acceleration robust observer for the Stewart platform is presented, and asymptotic stableness of algorithm is demonstrated by using Lyapunov method. Experi-ment results show that the controller proposed here has better trajectory tracking performance and higher capability of dealing with load coupling among actuators.

Key words: Electro-hydraulic servo control system, Nonlinear adaptive control, Sliding mode observer, Stewart platform