System identification and robust attitude control of an unmanned helicopter using novel low-cost flight control system

In recent years, unmanned aerial systems have attracted great attention due to the electronic systems technology advancements. Among these vehicles, unmanned helicopters are more important because of their special abilities and superior performance. The complex nonlinear dynamic system (caused by main rotor flapping dynamics coupled with the rigid body rotational motion) and considerable effects of ambient disturbance make their utilization hard in actual missions. Attitude dynamics have the main role in helicopter stabilization, so implementing proper control system for attitude is an important issue for unmanned helicopter hovering and trajectory tracking performance. Besides this, experimental utilization of low-cost flight control system for unmanned helicopters is still a challenging task. In this article, dynamic modeling, system identification, and robust control system implementation of roll and pitch dynamics of an unmanned helicopter is performed. A TRex-600E radio-controlled helicopter is equipped with a novel low-cost flight control system designed and constructed based on Raspberry Pi Linux-based microcomputer. Using Raspberry Pi makes this platform simpler to utilize and more time and cost-effective than similar platforms used before. The experiments are performed on a 5-degree-of-freedom testbed. The robust control system is designed based on H infinity method and is evaluated in real flight tests. The experiment results show that the proposed platform has the ability to successfully control the roll and pitch dynamics of the unmanned helicopter.