Integrated modeling to facilitate control architecture design for lightweight space telescopes

Abstract

The purpose of this thesis it to examine the effects of utilizing control to better meet performance and systematic requirements of future space telescopes. New telescope systems are moving toward tighter optical performance requirements with lower mass and cost, creating an implicit conflict for currently designed systems. Therefore, new technology and telescope types must be developed and implemented, and a key to lightweight systems is the addition of controls. This thesis uses an integrated modeling technique to examine a large tradespace of space telescope systems. The analysis techniques includes finite element and dynamic disturbance analyses to determine the effects of various parameters on overall system performance metrics. In particular, this thesis will focus on the control system architecture for future space telescopes. As systems become less massive, more control is necessary to meet the performance requirements. Less massive systems have more flexibility, which degrades performance. Thus, this flexibility must be controlled to obtain adequate performance. However, the control also has a cost that must be considered.

(cont.) As the areal density of the mirror decreases, the cost due to mass decreases, but the cost due to control increases because more control is required to meet the requirements. Therefore, a balance between lightweight systems and control is sought to give the best overall performance. Additionally, there are many different types of control that could be used on the system, thus finding optimal combinations of controllers, sensors, actuators, and bandwidths is a daunting task. The integrated modeling technique allows the designer to examine the effects of structural parameters and requirements on the control system architecture and the performance metrics. The ability to determine favorable control system architectures early in the design process will allow new technologies to be pushed further, while still maintaining confidence that the system will perform as expected.