Attitude Control Optimization for a Small-scale Unmanned Helicopter

This paper presents results from the attitude control optimization for a small-scale helicopter by using an identified model of the vehicle dynamics that explicitly accounts for the coupled rotor/stabilizer/fuselage (r/s/f) dynamics. The accuracy of the model is verified by showing that it successfully predicts the performance of the control system currently used for Carnegie Mellon’s autonomous helicopter (baseline controller). Elementary stability analysis shows that the light damping in the coupled r/s/f mode, which is due to the stabilizer bar, limits the performance of the baseline control system. This limitation is compensated by a second order notch filter. The control system is subsequently optimized using the CONDUIT control design framework with a frequency response envelope specification, which allows the attitude control performance to be accurately specified while insuring that the lightly damped r/s/f mode is adequately compensated.