Design and utility assessment of attitude control systems for EVA task performance

Abstract

Low gravity astronaut extravehicular activity (EVA) missions using a maneuvering Jetpack and robotic servicing and assembly missions could benet from spacecraft systems capable of maintaining pointing stability during critical operations. The addition of single-gimbal control moment gyroscopes (CMGs) to the attitude control system of these spacecraft could substantially improve the stability and pointing accuracy of the platform and could also conserve onboard fuel during missions. This thesis contains a description of recent work completed at Draper Laboratory and MIT's Space Systems Laboratory (SSL) and Man Vehicle Laboratory (MVL) that explores the performance and utility of a combined control concept for a Jetpack system using thrusters and CMGs as actuators. Simulation of the Mobility Augmenting Jetpack with Integrated CMGs (MAJIC) at Draper is described as well as the design, integration and physical demonstration of a combined control system with the Synchronized Positoin Hold Engage Reorient Experimental Satellite (SPHERES) facility at the SSL. Primary contributions in simulation for the Jetpack application have focused on implementing a new method for sizing CMG actuators and improving the performance and utility assessment strategies to compare a proposed MAJIC system with a Jetpack that does not include CMGs. Primary contributions with hardware within the context of the SPHERES facility have included the design, simulation, integration and testing of a CMG peripheral actuator package and associated laboratory and reduced-gravity testing with NASA's Flight Opportunity Program.