Dynamic Time Warping to Quantify Structural Maneuver Variability

Regime recognition (RR) enables indirect characterization of high and low cycle fatigue damage to critical aircraft components during fleet usage based on structural maneuvers and measured loads from a flight test program. To ensure that an RR algorithm is suitable for usage or condition-based maintenance (UBM/CBM), it is arguably necessary to guarantee that it performs consistently during the design phase, when presented with structural maneuvers precisely executed by test pilots during a flight test program, and during deployment, when presented with general maneuvers flown by fleet pilots that include damaging structural maneuvers or something similar enough to be considered structural maneuvers. Dynamic time warping (DTW) is used to provide a framework to efficiently and automatically identify flight segments in fleet data that resemble flight-test structural maneuvers for which component loads are known; a normalized metric based on DTW distance measures is proposed to quantify the similarity and control the procedure to pull similar maneuvers from the fleet data. The resultant distribution of this metric is used to quantify variability of a structural maneuver of interest and in turn provide guidance on the number of unique maneuvers that should be used in a verification and validation (V&V) process to analyze a candidate RR algorithm.