Abstract: In order to restrain the coupled disturbance of each degree of freedom of the hydraulic Stewart platform, combination tracking errors, which consist of the tracking errors of each degree of freedom and the coupled position error, are proposed in this article through Taylor series expansion of the trajectory. The coupled position error expressed by the differential position errors of each two neighbor degrees of freedom is used to represent the result of the action of the coupling disturbance. Backstepping design methodology is adopted to develop an adaptive robust position tracking controller with uncertain parameters in the system dynamics. Both parts of the combination tracking errors are shown to be exponentially stable under the proposed control law. Simulation results with the combination of AMESim and MATLAB demonstrate the effectiveness of the approach as contrasted with the traditional proportionintegrationdifferentiation (PID) controller in improving the error tracking of each degree of freedom with coupling disturbance.

Key words: adaptive control systems, trajectory tracking, backstepping, coupling attenuation, Stewart platform