Analysis 0f Hexapod

Abstract

The project ‘Structural design, analysis and optimization of space subsystem - Hexapod’ was carried out during a research internship at Space Applications Center, ISRO. The aim of the project was to design, analyze and optimization of Hexapod consisting of 6 Actuator assembles, to adjust a space telescope's primary mirror segments' inclination and location.

A space telescope is a device intended to be used to capture images of space entities to make progress in research on celestial objects and space events. Over time, the requirement for larger primary mirrors inspired scientists to work on foldable primary mirrors. This kind of mirror consists of multiple segments, where each segment is attached on a mechanism that can finely position the mirror segment. This mechanism is called a Hexapod. Since it allows for exact control of the position and orientation of primary mirror segments, the development of high-precision hexapod mechanisms has been a crucial field of research for space telescope technology. A space telescope's resolution and image quality depend on accurate mirror alignment, which is necessary for the telescope to operate properly.

For the optical alignment of enormous mirrors in space telescopes, an incredibly precise positioning device has been created. In a novel arrangement, the design uses conventional mechanical parts including gears, bearings, and flexures. Analysis of a hexapod configuration consisting of Mirror, Delta frame and 3 Actuator Bipod assembly. This focuses on the development and analysis of a highly precise mechanical actuator system for a segmented mirror telescope used in space observations. The segmented mirror telescope offers advantages such as reduced launch size and a larger primary mirror surface for collecting large amounts of data. However, precise positioning and refocusing of the mirrors are essential to obtain accurate observations. To achieve this, a hexapod configuration is used to provide 6 degrees of freedom to the mirror, including three axis in translation and three axis in rotation. The study involved performing different FEA analyses, including Structural, Translation and Rotational Simulation, Modal, frequency response and random response analysis to check the mirror system's performance under various loading conditions. Based on the results, appropriate design changes were made, and the final design proved to perform correctly under different loading conditions. This study provides valuable insights into the development and analysis of highly precise mechanical actuator systems for space telescope applications.