SDRE flight control for X-Cell and R-Max autonomous helicopters

This paper presents a state-dependent Riccati equation (SDRE) flight control approach and its application to autonomous helicopters. For our experiments, we used two different vehicles: an X-Cell-90 small hobby helicopter and a larger vehicle based on the Yamaha R-Max. The control design uses a 6-DOF nonlinear dynamic model that is manipulated into a pseudo-linear form where system matrices are given explicitly as a function of the current state. A standard Riccati equation is then solved numerically at each step of a 50 Hz control loop to design the nonlinear state feedback control law on-line. In addition, a static nonlinear compensator is designed to address issues with the mismatch between the original nonlinear dynamics and its pseudo-linear transformation.