System identification and attitude control of a small scale unmanned helicopter

This paper copes with the problem of identifying the attitude dynamics of a small scale helicopter using the frequency sweep technology based on the flight data collected near the hovering condition. The frequency domain responses of a helicopter in the lateral, longitudinal and yaw channels are analysed by the partial coherence method, and the transfer functions are obtained by the weighted fitting method. The proposed method can identify the attitude dynamics including the actuator dynamics using the flight data only without carrying out any additional ground experiments. The models identified are verified by comparing model outputs with the experimental data on a small scale helicopter in our lab. We also carried out experiments on the attitude control of the helicopter to further validate the identified models.