Autonomous aerobatics on commanded path

A guidance and control scheme for a fixed-wing aircraft that enables autonomous aerobatics on commanded path is presented. The proposed method utilizes the nonlinear path-following guidance law in the outer-loop, which creates an acceleration command for a given desired path, current position and velocity of the vehicle. The scheme considers the gravity outside the inner-loop, in that gravitational acceleration is subtracted from the acceleration command to form the specific force acceleration command. With the gravity term removed, the specific force acceleration is more easily controlled in the inner-loop compared to the total acceleration. For an aircraft with sufficient side-force authority a roll attitude is not constrained but can be selected. As a result a roll-to-inverted flight and active sideslip maneuvers such as knife-edge and slow roll are accomplished. Applications to a series of standard aerobatic maneuvers are demonstrated through flight tests to show the performance of the proposed method.