Unmanned coaxial rotor helicopter dynamics and system parameter estimation

A numerical model that estimates the parameters of a small, unmanned coaxial rotor helicopter with a takeoff mass of 11.9 kg was developed. The modeled coaxial rotor helicopter did not have any additional damping to its dynamics such as a stabilizer bar or external gyro, which are common in commercial hobby helicopter models. Therefore, any sinusoidal actuator input from manual flight led to a large deviation of attitude rates, resulting in uncontrollable situations. A feedback attitude controller was included during test flights and parameter estimation to address this problem. Time domain experimental data were used to help estimate and validate the parameters of the helicopter. Attitude responses predicted by the model show extremely small discrepancies with experimental data. Therefore, the developed numerical model can be used for coaxial rotor helicopter controller design and other simulation purposes.