A global strategy for tailsitter hover control

Abstract

We present a nonlinear hover controller for a small flying wing tailsitter vehicle, which enables recovering to hover from a large set of initial conditions. The proposed attitude control law is obtained by solving an optimal control problem, with the objective of correcting large attitude errors by turning primarily around the vehicle’s strongly actuated axis. Solutions for a set of initial attitudes are precomputed and stored in a lookup table. For each controller update, the optimal inputs are read from this table, and applied to the system in an MPC-like manner. Simulation results indicate that this control method is able to perform recoveries to hover from any initial attitude, given that the initial velocity of the vehicle is below a certain limit. Further, the performance of the control strategy is demonstrated on a small tailsitter vehicle in the ETH Zurich Flying Machine Arena.