Engineering topics
Publications and source records attributed to Spanos, J..
In this paper we present the results of a study to identify a nonlinear bending mode for a 60 meter space structure.
The Shuttle Radar Topography Mission is the first mission to provide high accuracy near-global topographic coverage of the Earth's land surface using a long-baseline interferometry approach.
We present a narrow-band tracking control using a variant of the Least Mean Square (LMS) algorithm [1,2,3] for supressing automobile engine/drive-train vibration disturbances. The algorithm presented here has a simple structure and may be implemented in a low cost micro controller.
Conditions are investigated for exponential convergence of the tracking error in feedforward adaptive systems without persistent excitation.
Persistent excitation conditions which ensure parameter convergence in adaptive algorithms have been studied by many researchers. Here, conditions are investigated for exponential convergence of the tracking error in feedforward adaptive systems without persistent excitation. Particular attention is paid to the continuous-time LMS algorithm in the overparametrized case. Results are presented.
An experimental implementation of a nanometer level optical pathlength control for large baseline space interferometry is presented. The pathlength compensation system is installed on a large flexible experimental truss, thus structural motions play a dominant role in the control system design. The associated control structure interaction problem is addressed to maintain the optical pathlength within the prescribed variation of 10-15 nanometer rms. By a successful blend of a structural control for damping augmentation and a direct pathlength control for the pathlength compensation, the optical pathlength variation has been maintained within 6 nonometer rms under the laboratory ambient disturbance and within 9 nonmeter rms under a severe forced resonant disturbance.
The paper describes experimental research in the are of active vibration isolation. The objective of the research is to quantitavely assess the performance gained by augmenting a passive isolator will an active stage.