Adaptive Control of a 3-DOF Helicopter Under Structured and Unstructured Uncertainties

In this paper, an adaptive control strategy is presented for a three-degree-of-freedom helicopter under both structured and unstructured uncertainties. The adaptive control scheme learns online the helicopter’s inverse model with a Lyapunov-based adaptation law to estimate the system’s parameters. Moreover, a reference model is introduced to stabilize the helicopter at start-up and cope with unstructured uncertainties such as external disturbance. Therefore, the controller achieves accurate motion tracking in the presence of both structured uncertainties (parameters variation) and unstructured uncertainties (unknown disturbance). Unlike many controllers, the proposed adaptive control scheme’s stability is guaranteed by Lyapunov direct method. The proposed controller’s performance in coping with various uncertainties is highlighted in different operating conditions.