System Identification and Control System Design for the BURRO Autonomous UAV

An initiative was undertaken to develop key enabling technologies for the control and simulation of rotorcraft uninhabited air vehicles. Under this initiative, system identification and control law design for an unmanned version of the Kaman Aerospace K-MAX helicopter was completed. The unmanned mission consists of autonomously ferrying supplies from ships to inland troops at multiple sites and return, with remote pilot control for takeoff and landing phases. System identification of a hovering K-MAX with and without an external load was performed in the frequency domain using flight data provided by Kaman Aerospace. The results represent the first state-space identification of a coupled helicopter-slung load configuration. Special features of the identification include significant differences in coupling and stability of the intermeshing twin-rotor K-MAX compared to conventional single rotor helicopters, and parameters that identify the increased dynamic inflow of the intermeshing rotors and the load pendulum roots. After identification of the system math models, control laws were optimized to meet requirements adapted from piloted aircraft specifications. The optimized control laws met the requirements for adequate stability margins and satisfactory handling qualities and were successfully flown in recent flight tests.