Chapter 5 Robust Performance Tailoring with Tuning - SSL - MIT

Chapter 2
Performance Tailoring
A common approach to designing high-performance systems is to use optimization
techniques to find a design that meets performance requirements [113, 26, 56, 109, 62,
51]. One popular problem statement is the design of a minimum mass structure given
constraints on load carrying capability or first natural frequency. In this example, the
objective is a static quantity; the mass of the structure does not change over time.
In contrast, the structural control problem posed by space-based interferometers has
driven the need for both structural and control optimization with a dynamic objec-
tive such as output variance or frequency response. In these problems the objective
function changes with time due to dynamic loading on the structure. Langley et al.
consider the minimization of kinetic energy and maximum strain energy by variation
of truss bay length and bay loss factor [68]. Moshrefi-Torbati, Keane et al. reduce the
frequency-averaged response of a truss by varying the truss topology [91]. The use
of optical performance metrics as cost functions is addressed by both Bronowicki [22]
and Milman et al [89].
In this thesis, the term Performance Tailoring (PT) is applied to structural opti-
mizations in which the goal is to tailor the structure to meet a dynamic performance
requirement. This chapter provides a formal definition of performance tailoring and
gives an illustrative example using a simple structural model that is representative
of a structurally-connected interferometer. The model details are presented and the
PT problem is formulated specifically for the problem of minimizing the RMS of an
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