|
PHD THESIS ABSTRACT
Precision opto-mechanical systems, such as space telescopes, combine structures, optics and controls in order to meet stringent pointing and phasing requirements. In this context a novel approach to the design of complex, multi-disciplinary systems is presented in the form of a multivariable isoperformance methodology. The isoperformance approach first finds a point design within a topology, which meets the performance requirements with sufficient margins. The performance outputs are then treated as equality constraints and the non-uniqueness of the design space is exploited by trading key disturbance, plant,
optics and controls parameters with respect to each other.
Three algorithms (branch-and-bound, tangential front following and vector spline approximation) are developed for the bivariate and multivariable problem. The challenges of large order models are addressed by presenting a fast diagonal Lyapunov solver, apriori error bounds for model reduction as well as a governing sensitivity equation for similarity transformed state space realizations.
Specific applications developed with this technique are error budgeting and multiobjective design optimization. The isoperformance approach attempts to avoid situations, where very difficult requirements are levied onto one subsystem, while other subsystems hold substantial margins. An experimental validation is carried out on the DOLCE laboratory testbed trading disturbance excitation amplitude and payload mass. The predicted performance contours match the experimental data very well at low excitation levels, typical of the disturbance environment on precision opto-mechanical systems. The relevance of isoperformance to space systems engineering is demonstrated with a comprehensive NEXUS spacecraft dynamics and controls analysis. The isoperformance approach enhances the understanding of complex opto-mechanical systems by exploiting physical parameter sensitivity and performance information beyond the local neighborhood of a particular point design.
|
|
