Optimal Control Framework for Gust Load Alleviation using Real Time Aerodynamic Force Prediction from Artificial Hair Sensor Array

摘要

Novel artificial hair sensors, recently developed at the AFRL, possess many important features such as low cost, low power consumption, easy integratibility, low foot-print, high bandwidth etc. and are ideal for distributed surface flow sensing without affecting the flow. These sensors are capable of extracting flow features such as local flow velocity, local shear, leading edge stagnation point, flow separation points as well as the prediction of real-time force and moments. Measurement of surface flow features and force/moments enables real-time estimation of unsteady aerodynamic states that are not directly observable. The ability to estimate all possible states makes it possible to use multivariable feedback control based on modern state space control theory. In this paper, we present an optimal control framework for active gust load alleviation on a flap actuated typical 2DOF wing section that uses the force and moment prediction from arrays of artificial hair sensors and artificial neural network. For the system under study, initial results show that the control surface is effective in adding the damping in pitch DOF compared to plunge DOF. A state and control cost analysis also shows that the state cost cannot be minimized below certain value regardless of control effort thereby warranting the need for additional control effectiveness. The system dynamics allows estimation of states just with lift measurement, this excludes the needs of noisy moment measurement for state estimation. State estimation using wind tune test validates that lift can be used for full state estimation in pitch-plunge system. The control simulation shows that the combined estimator-optimal controller is effective to suppress the gust induced vibration. This work represents the first characterization of the ability of artificial hair sensors to estimate unsteady aerodynamic states for use in state-space control.