Department of Electrical and Electronics Engineering
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Item Asymmetric UAV Performing Pointing Maneuver Under Lateral CG Offset: An Adaptive Backstepping Control Approach(IEEE, 2023) Mukherjee, Bijoy K.This work addresses the complex issue of autonomously executing the maneuvers with fixed-wing Unmanned aerial vehicles (UAV), which can experience significant lateral center of gravity (c.g.) variations due to uneven cargo loading or release. The study establishes that the asymmetric flight dynamics of the UAV, caused by laterally shifted c.g., can be effectively represented in a block strict feedback form. Subsequently, an adaptive backstepping controller is proposed to enable the closed-loop system to adapt to c.g. variations. The controller’s stability is proven using Lyapunov’s method. To verify the effectiveness of the proposed control scheme, simulations are conducted involving pointing maneuvers with the Aerosonde UAV. The results demonstrate that the proposed scheme exhibits high resilience to lateral c.g. variations and achieves superior tracking performance.Item Lateral Maneuvering with a UAV Mitigating Lateral CG Variations: Modeling and an Efficient Adaptive Backstepping Control(World Scientific, 2024) Mukherjee, Bijoy K.In this paper, an adaptive backstepping-based control scheme is proposed to perform autonomous lateral maneuvers under significant lateral offset in the center of gravity (c.g.) position in a UAV. It is first shown that the coupled equations of motion arising from lateral c.g. shift can be simplified and cast in block strict feedback form making it amenable to a two-step backstepping control design. Useful nonlinear terms in the equations of motion are identified and retained in the backstepping design to ensure a less conservative control. Adaptation law is incorporated to dynamically adjust to changes in the c.g. position by adding an adaptive term to each step of the backstepping control. Lyapunov’s direct method and LaSalle’s invariance principle are applied to establish asymptotic stability of both tracking errors and errors in the c.g. estimate. To validate the effectiveness of the proposed control strategy, simulation results for horizontal turn maneuver are presented for the fixed wing Aerosonde UAV and maneuver performance is observed to remain highly insensitive to a wide range of lateral c.g. positions on either side of the fuselage centerline. Furthermore, a comparative control performance analysis is carried out against an ad-hoc model-based adaptive backstepping control scheme available in the literature and the results show significant performance enhancement in the proposed scheme. Along with the c.g. variations, the effects of steady crosswind are also investigated and the control formulation is modified to mitigate these effects too. Real-time control hardware in loop simulations are also provided in support of the real time viability of the proposed control.Item High-α maneuver under lateral centre of gravity uncertainty: A robust adaptive backstepping control scheme(Sage, 2024-08) Mukherjee, Bijoy K.The present note addresses the novel problem of executing complex aircraft maneuvers under considerable center of gravity (c.g.) uncertainties arising from asymmetrical loading or release of payloads, uneven fuel consumption etc. First, the aircraft flight dynamics under predominantly lateral c.g. movement, is approximated and expressed in a block strict feedback form and thereafter an adaptive backstepping controller is proposed to adapt to the c.g. variations. To alleviate the model uncertainty caused by this model approximation and also to provide robustness to aerodynamic uncertainties in high-alpha regions, a sliding mode control is further integrated with the adaptive backstepping control law. Asymptotic stability conditions of the proposed controller are derived from the first principle using Lyapunov’s method and Barbalat’s lemma. To validate the proposed control scheme, the high-alpha Herbst maneuver is implemented in simulation for the F18-HARV aircraft and the results show that the maneuver performance remains nearly the same under both the nominal and the off-nominal c.g. positions.