Development and experiment of active member for space-base precise pointing Hexapod

A platform scheme that provides precision pointing and active vibration isolation for space-base payloads based on parallel mechanism-Hexapod was proposed. With the analysis of the current Hexapod-s actuators, a high precision dual-driving hybrid actuator was developed. It integrated ball-screw actuator as macro-moving stage and piezoelectric stack actuator as micro-moving stage. Key characteristics of the hybrid actuator were measured at first, such as stroke, macro-moving stage open-loop positioning accuracy and micromoving stage dynamic property. An experiment system based on MATLAB/dSPACE environment was established and the actuator single degree-of-freedom positioning experiment and active vibration isolation experiment were carried on then. Experiment results show that the hybrid actuator stroke exceeds 50mm and its whole positioning error being less than 1μm with the close-loop compensation of the micro-moving stage. The results also show that when continuously excited at 30Hz on one end of the hybrid actuator, vibration on the other end is decreased more than 90% with the adaptive filtering active disturbance canceller (ADC) algorithm. The study indicates that the hybrid actuator is expected to apply to precise pointing Hexapod.