Controllability and Design of Unmanned Multirotor Aircraft Robust to Rotor Failure

A new design method for multi-rotor aircraft with distributed electric propulsion is presented to ensure a property of robustness against rotor failure from the control perspective. Based on the concept of null controllability, a quality measure is derived to evaluate and quantify the performance of a given design with the consideration of rotor failure. An optimization problem whose cost function is based on the quality measure is formulated and its optimal solution identifies a set of optimal design parameters that maximizes an aircraft’s ability to control its attitude and hence its position. The effectiveness of the proposed design procedure is validated through the results of experimentation with the Autonomous Flying Ambulance model being developed at Caltech’s Center for Autonomous Systems and Technologies

Aerodynamic Modeling and Parameter Estimation of a Quadrotor Helicopter

This study focuses on aerodynamic modeling of a quadrotor helicopter and the estimation of the model parameters in wind tunnel tests for hover, vertical climb, and forward flight conditions. The motion of a quadrotor is mainly affected by the aerodynamic forces and moments generated by rotors. Accurate calculation of rotor loads is essential for high fidelity simulation of a quadrotor. Momentum and blade element theories are used to obtain expressions for rotor forces and moments for a traveling vehicle. The parameters of the models are then identified through wind tunnel tests where the forces and moments created under various wind conditions and rotor speeds are measured with a six axes balance system