Abstract: H_∞ parameter identification for inflight icing detection is discussed in this paper for the development of the de-icing and anti-icing system of a large icing research prototype. First, the H_∞ method parameters are tuned and chosen.Then the method is evaluated by the airplane's longitudinal simulation data with measurement noises. The identification results show that the method can track the time-varying aerodynamic parameters in the ice accretion process, and that the maximum normalized Root Mean Square(RMS) error 11% indicates high accuracy of identification.The 81 different ice accretion processes are then identified by the H_∞ method.The results show that when the ice accretion process changes slowly and lasts long the identification accuracy is relatively poor, and that when the ice accretion time is between 100-300 s the accuracy is relatively high. The accuracy of H_∞ algorithm in the different standard deviations of measurement noises is analyzed by Monte Carlo simulation.The error and delay statistic characteristics of the three longitudinal aerodynamic derivatives show that the identification accuracy of derivatives of lift and pitching moment to angle of attack is relatively high as their mean normalized RMS errors are 1.8% and 4% respectively, and their mean delays are 3 s and 9.5 s respectively.

Key words: H_∞ filter, aircraft icing detection, ice accretion process, measurement noise, parameter identification