Use of evolutionary computation techniques for exploration and prediction of helicopter loads

The development of accurate load spectra for helicopters is necessary for life cycle management and life extension efforts. This paper explores continued efforts to utilize evolutionary computation (EC) methods and machine learning techniques to estimate several helicopter dynamic loads. Estimates for the main rotor normal bending (MRNBX) on the Australian Black Hawk helicopter were generated from an input set that included thirty standard flight state and control system parameters under several flight conditions (full speed forward level flight, rolling left pullout at 1.5g, and steady 45° left turn at full speed). Multi-objective genetic algorithms (MOGA) used in combination with the Gamma test found reduced subsets of predictor variables with modeling potential. These subsets were used to estimate MRNBX using Cartesian genetic programming and neural network models trained by deterministic and evolutionary computation techniques, including particle swarm optimization (PSO), differential evolution (DE), and MOGA. PSO and DE were used alone or in combination with deterministic methods. Different error measures were explored including a fuzzy-based asymmetric error function. EC techniques played an important role in both the exploratory and modeling phase of the investigation. The results of this work show that the addition of EC techniques in the modeling stage generated more accurate and correlated models than could be obtained using only deterministic optimization.