Error modeling and accuracy analysis of a multi-level hybrid support robot

As for the multi-level hybrid feed support robot in the Five-hundred-meter Aperture Spherical radio Telescope (FAST), the cabin´s time-varying barycenter and structural deformation are main factors causing the terminal receivers´ pose error. In order to ensure tracking accuracy of astronomical observations, firstly the elasticity model of the cable-driven Stewart manipulator is deduced to analyze the terminal error caused by the gravity torque. Newton-Raphson method is adopted to acquire the terminal error range and propose compensation strategy. Then error model considering structural deformation is formulated and the terminal accuracy is analyzed with an improved set theory based method. Finally the sensitivity analysis is also carried out and accuracy synthesis is implemented. Error modeling and analysis method proposed for the support robot in this paper can also be used to other complex hybrid robots with either large dimension or heavy duty.