Ganeshnavar Santoshkumar et. al; International Journal of Advance Research, Ideas and Innovations in Technology © 2018, www.IJARIIT.com All Rights Reserved Page | 2248 ISSN: 2454-132X Impact factor: 4.295 (Volume 4, Issue 3) Available online at: www.ijariit.com Study of unfurlable mechanism for space radars Santoshkumar Ganeshnavar sganeshnavar2@gmail.com Electronics And Radar Development Establishment (DRDO), Bengaluru, Karnataka Shreeshial B bshreeshial@gmail.com Electronics And Radar Development Establishment (DRDO), Bengaluru, Karnataka Ajai Kumar Shrivastava ajai.kr.shrivastava@lrde.drdo.in Electronics And Radar Development Establishment (DRDO), Bengaluru, Karnataka Sivakumar S. sivakumar.s@lrde.drdo.in Electronics And Radar Development Establishment (DRDO), Bengaluru, Karnataka Jai Kumar V Jaikumar.v@lrde.drdo.in Electronics And Radar Development Establishment (DRDO), Bengaluru, Karnataka ABSTRACT Unfurlable rim truss antennae are considered to be the most suitable for developing large size aperture structures for space antenna. They have largely deployed to stowed volume ratio, precision, and reliability in its operation. The mechanism is capable of altering its configuration from a stowed to deployed shape to meet specific operational requirements of space-borne radar. The proposed study of unfurlable mechanism for paraboloid reflector antenna is made up number of parallelogram units comprised of links with appropriate hinge joints, which concatenate in a repeatable fashion to form the desired structure. This study include geometric modeling, kinematic simulation and preliminary structural analysis of unfurlable rim truss. Keywords: Unfurlable mechanism, Rim truss, Offset fed paraboloid reflector, Simulation 1. INTRODUCTION Large unfurlable antennae have been built for spaceborne radars with different structural schemes, most of them can be classified as radial structures, modular structures, and rim truss. Among these, rim truss antenna with the advantage of high thermo-elastic stability and deployment reliability is investigated for the past few years. Miyasaka, A. and Hommat M. [1] have designed deployable rim truss mechanisms which are extensively used to fulfill the requirement of large aperture antenna in space environment than one can be carried to space orbit. Pei Li et.al [2] have presented research work on geometrical modeling and dynamic behaviour of support rim structure for mesh deployable antenna and it can be observed that the deployable rim truss has circular contour to support prime focus parabolic reflector system and for that of offset fed parabolic reflector system it is required have elliptical contour deployable support structure. Mark W. Thomson [3] has explained the concept used in deployable reflectors developed by AstroMesh Corporation. Xiaozhi Qi, et.al [4] have discussed on the detail geometrical modeling process for both axis symmetric parabolic reflector and offset fed parabolic reflector antenna. L. Datashvili [5] has done research to develop the concept of double pantograph based peripheral ring which satisfies the demand of significantly less mass and smaller folded volume while maintaining stability and deployment reliability. Zhang Yiqun et.al [6] studied kinematic simulation of Deployable Polyhedral Truss (DPT) used especially for large aperture antennae. S. Laxminarayan et.al [7] has used ADAMS software to carry out the kinematic analysis of deployable polyhedral truss of 18 bays. All the units rim truss structure has a single degree of freedom; one translation motion input is given to the telescopic diagonal member of the first unit. The motion of the first unit is transmitted to the next and subsequent units through gears. For offset fed parabolic reflector antenna, the support unfurlable rim truss structure has an elliptical shape, so each hinge has different angles to connect vertical and horizontal links of deployable rim truss. So the objective of this study is geometric modeling, kinematic simulation and preliminary structural analysis of unfurlable rim truss for offset fed paraboloid reflector antenna. The proposed study of an unfurlable mechanism for paraboloid reflector antenna is made up of a number of parallelogram units known as bays comprised of links with appropriate hinge joints, which concatenate in a repeatable fashion to form the desired structure. Each of these bays undergoes determined relative motion between the links to transform the mechanism from an initially compact state to unfurlable state. In the present development, the rimtruss has 30 bays forming a 30 equal sided polygon. Each bay is connected to the adjacent bays through revolute joints. A cable is routed through all the diagonal members of the rim