Simultaneous precision positioning and vibration suppression of an intelligent composite satellite structure utilizing piezoelectric sensors and actuators

Adaptive or intelligent structures which have the capability for sensing and responding to their environment promise a novel approach to satisfying the stringent performance requirements of future space missions. This research effort focuses on the development of a smart thruster mount truss structure with precision positioning and active vibration suppression capability for use in a space satellite. The smart thruster mount would utilize piezoelectric sensors and actuators for precision positioning to provide fine tuning of position tolerance for thruster alignment. The same structure may be used for suppressing the vibration that resonates throughout the spacecraft during thruster firing. This vibration renders sensitive optical or measurement equipment non-operational until the disturbance has dissipated. This smart system approach would greatly enhance mission performance by fine tuning attitude control, potentially eliminating the nonoperational period as well as minimizing fuel consumption utilized for position correction.; The configuration of the smart thruster mount truss system is that of a modified Stewart platform. Precision positioning of the truss structure is achieved using active members which extend or contract to tilt the upper platform where the thruster is mounted. An inverse kinematic analysis of a modified Stewart platform has been developed and is used to determine the required axial displacement of the active struts for the desired angular tilt of the smart platform. Experimental data is used to verify the precision positioning capabilities of the active struts. This information demonstrates the ability of the active strut to tilt the top of the smart platform by the required angular displacement.; Analytical verification of the vibration suppression capabilities of the active struts in the smart composite platform using finite element analysis is presented. A model of an active strut with surface mounted sensors/actuators was used to develop a vibration suppression scheme. This technique was used successfully to analytically demonstrate both the lateral and axial vibration suppression capability of the active strut.; The numerical and experimental results show that the proposed smart platform offers a promising method for achieving fine tuning of positioning tolerances of a thruster as well as minimizing the effect of the disturbance generated during thruster firing.