Design of DDP controller for autonomous autorotative landing of RWUAV following an engine failure

A Rotary-Wing Unmanned Aerial Vehicle (RWUAV) in the 500 kg class capable of fulfilling a number of missions, would represent a considerable capital outlay for any customer, as both the RWUAV as a platform and its payload comprising sophisticated sensors would be costly items. Therefore, in the event of an engine failure, a means should be provided to get the RWUAV safely back on the ground without incurring damage. A Differential Dynamic Programming (DDP) control algorithm was designed to compute the main and tail rotor collective pitch and the longitudinal and lateral cyclic pitch control inputs to safely land the RWUAV. The results obtained were compared to the flight simulation response. The main rotor dynamics, which are critical in a successful execution of an autorotative landing, were acceptably well modelled.