A lateral/directional state-space model of the Raptor 50 helicopter is identified in forward flight condition. A frequency sweep test is properly designed and executed to collect a well-suited time-history database. The measured accelerometers are transferred from the sensor location to the gravity, then, a complete set of non-parametric input-to-output frequency responses that fully characterizes the coupled helicopter dynamics are extracted from the frequency sweep test data. With the help of small perturbation theory, a linearized dynamic model for the stability and control derivative is extracted from linearization of a nonlinear mathematical model. A nonlinear search based on secant method is conducted for the linear lateral/directional state-space model that matches the frequency-response data set. The identified model is verified in the time domain, which indicates that the model matches the flight data well. © 2010 Published by Elsevier Ltd.
Liu, P., Meng, Z., & Wu, Z. (2011). Identification of lateral/directional model for a UAV helicopter in forward flight. In Procedia Engineering (Vol. 16, pp. 137–143). https://doi.org/10.1016/j.proeng.2011.08.1063