A Stochastic Global Identification Framework for Aerospace Vehicles   Operating Under Varying Flight States
  In this work, a novel data-based stochastic global identification framework is introduced for air vehicles operating under varying flight states and uncertainty. In this context, the term global refers to the identification of a model that is capable of representing the system dynamics under any admissible flight state based on data recorded from sample states. The proposed framework is based on stochastic time-series models for representing the system dynamics and aeroelastic response under multiple flight states, with each state characterized by several variables, such as the airspeed and angle of attack, forming a flight state vector. The method's cornerstone lies in the new class of Vector-dependent Functionally Pooled (VFP) models which allow the explicit analytical inclusion of the flight state vector into the model parameters and, hence, system dynamics. The experimental evaluation is based on a prototype bio-inspired self-sensing composite wing that is subjected to a series of wind tunnel experiments. Distributed micro-sensors in the form of stretchable sensor networks are embedded in the composite layup of the wing to provide the sensing capabilities. Data collected from piezoelectric sensors are employed for the identification of a stochastic global VFP model. The estimated VFP model parameters constitute two-dimensional functions of the flight state vector defined by the airspeed and angle of attack. The identified model is able to successfully represent the aeroelastic response of the wing under the admissible flight states via a minimum number of estimated parameters compared to standard identification approaches. The obtained results demonstrate the high accuracy and effectiveness of the proposed global identification framework, thus constituting a first step towards the next generation of fly-by-feel aerospace vehicles with state awareness capabilities. 
Fotis Kopsaftopoulos, Raphael Nardari, Yu-Hung Li, Fu-Kuo Chang
cs.SY