Flight control of a large-scale flapping-wing flying robotic bird: System development and flight experiment

Large-scale flapping-wing flying robotic birds have huge application potential in outdoor tasks, such as military reconnaissance, environment exploring, disaster rescue and so on. In this paper, a multiple modes flight control method and system are proposed for a large-scale robotic bird which has 2.3 m wingspan and 650 g mass. Different from small flapping wing aerial vehicle, the mass of its wings cannot be neglected and the flapping frequency are much lower. Therefore, the influence of transient aerodynamics instead of only mean value are considered in attitude estimation and controller design. Moreover, flight attitude and trajectory are highly coupled, and the robot has only three actuators----one for wings flapping and two for tail adjustment, it is very difficult to simultaneously control the attitude and position. Hence, a fuzzy control strategy is addressed to determine the command of each actuator by considering the priority of attitude stabilization, trajectory tracking and the flight safety. Then, the on-board controller is designed based on FreeRTOS. It not only satisfies the strict restrictions on mass, size, power and space but also meets the autonomous, semi-autonomous and manual flight control requirements. Finally, the developed control system was integrated to the robotic prototype, HIT-phoenix. Flight experiments under different environment conditions such as sunny and windy weather were completed to verify the control method and system.