Fundamental performance of a smart structural system utilizing thermal expansion for pointing

Abstract

This study involved designing and developing a smart structural system for pointing control of large-scale trusses. The system consisted of a pointing control mechanism, an internal displacement-sensor, and a controller. The significant points of the system included the following: (1) artificial thermal expansions of truss members were utilized as linear actuators, (2) elastic hinges were employed instead of ball joints, and (3) the internal displacement-sensor that did not require external jigs and possessed high measuring accuracy was applied. The study involved conducting a feasibility study and an experimental demonstration. The results indicated that the pointing control mechanism produced a sufficient tilt angle to satisfy typical requirements of recent scientific satellites. Furthermore, the findings confirmed that the hysteresis of the pointing control mechanism could be kept sufficiently small due to the absence of sliding parts. The difference between the finite element analysis and the measured value corresponded to $2.9\%$ for a $3.6\mathrm{m}$ long truss. Additionally, the results suggested that the proposed smart structural system for pointing exhibited high control accuracy and tracking performance for a periodic motion. The root mean square error value for a circular trajectory with a radius of $500\mu \mathrm{m}$ for a period of $15\min$ corresponded to $4.6\%$ for the $3.6\mathrm{m}$ long truss.