Structural Health Monitoring and Risk Management of a Reusable Launch Vehicle

Abstract

A structural-health-monitoring system can contribute to the risk management of a structure operating under hazardous conditions. An example is the wing leading-edge impact-detection system that monitors the debris hazards to the Space Shuttle Orbiter's reinforced carbon-carbon panels. Since return to flight after the Columbia accident, the system was developed and subsequently deployed on board the orbiter to detect ascent and on-orbit debris impacts, so as to support the assessment of wing leading edge structural integrity before orbiter reentry. As structural health monitoring is inherently an inverse problem, the analyses involved, including those performed for this system, tend to be associated with significant uncertainty. The use of probabilistic approaches to handle the uncertainty has resulted in the successful implementation of many development and application milestones. Nomenclature d = damage size, in. G max = maximum acceleration response G rms = rms of acceleration response P = damage probability P C = joint probability of critical damage P C=I = conditional probability of critical damage given an impact has occurred P F = probability of multisensor corroboration being weaker than flight experience P I = probability of impact P M = probability of multisensor corroboration being stronger than model experience r diag = diagonal corroboration ratio of multisensor response r horz = horizontal corroboration ratio of multisensor response = logarithmic decay dam = damage-G max correlation factor mea = test measurement scaling factor pan = reinforced carbon-carbon panel-to-panel test scaling factor sen = sensor configuration test scaling factor tst = test-article boundary condition scaling factor

Adaptive-gain multivariable super-twisting sliding mode control for reentry RLV with torque perturbation

“…During the reentry phase, RLV is subject to significant model uncertainties and severe torque perturbation. These, together with the fact that the boundaries of all uncertainties and perturbations are not known, make the reentry attitude control extremely challenging [1,2]. Therefore, a more advanced controller, which is robust to the uncertainties and disturbances without the control gains overestimation, would be a significant improvement over current RLV flight technology.…”