The purpose of this thesis is to investigate how autonomous robust flight with a miniature quadrotor can be done while minimizing the lag in time of a
fast moving reference.

A general introduction to how quadrotors work and how they are controlled are given. A mathematical model is derived for the X-3D quadrotor from Ascending Technology and an Extended Kalman Filter is used with a IMU-driven model to estimate the state doing flight, handle sensor fusion and handle failing sensors.

A LQR using various reference models and a Robust H controller are derived and tested. Good results was obtained with the LQR, but the H controller was not able to stabilize the quadrotor in real flight, only in simulation. It is assumed to be caused by the assumption made that the on-board controller is fast enough to ignore any dynamics caused by the controller, motor controller and aerodynamics.

The derived estimator in combination with the LQR, using feed forward of the reference velocity, was able to follow a fast trajectory with a minimum
of lag in time.