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 micro-moving 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 1 μm with the close-loop compensation of the micro-moving stage. The results also show that when continuously excited at 30 Hz 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.