Department of Electrical and Electronics Engineering
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Item Autonomous aircraft maneuvering under unknown CG variations through a robust adaptive backstepping control(Sage, 2025-01) Mukherjee, Bijoy K.The objective of the present article is to address the hitherto unaddressed problem of executing demanding autonomous aircraft maneuvers mitigating significant uncertainties in lateral center of gravity (c.g.) position. As a major contribution, it is shown that, under a reasonable simplifying assumption, a strict feedback form of the dynamics with affine in c.g. position can be derived from the highly coupled equations of motion that is caused by asymmetric c.g. variations. Thereafter, a two-step adaptive backstepping control is proposed adapting to the c.g. position automatically. Also, the useful nonlinearities in the dynamics are identified from the aircraft’s dataset and are retained to prevent a conservative control design. To provide further robustness to the aforementioned model simplification as well as to aerodynamic uncertainties, a fast adaptive sliding mode control is integrated with each of the two steps of the baseline adaptive backstepping control and the asymptotic stability of the overall system is proved using Lyapunov’s method. To validate the efficacy of the proposed control, the high angle of attack Herbst maneuver is simulated for the F18-HARV aircraft and nearly identical maneuver performance is achieved over a wide range of lateral c.g. variations on either side of the fuselage centerline. Real time hardware in loop simulations are also performed to establish the real time applicability of the proposed control.Item UAV Performing Level Turn Maneuver Under CG Offset: Backstepping Control Scheme(IEEE, 2023) Mukherjee, Bijoy K.When an Unmanned Aerial Vehicle (UAV) experiences uneven cargo loading or release, the center of gravity (c.g.) undergoes a lateral shift, leading to complex coupled and non-linear asymmetric dynamics. This poses significant challenges in controlling the UAV, particularly during lateral/directional maneuvers. To ensure the UAV's safety and stability, it becomes imperative to implement nonlinear control strategies. This study tackles the issue by first ad-hoc modeling the asymmetric dynamics and then effectively transforming them into strict feedback form. This transformation guarantees the desired level turn maneuver performance for a fixed-wing UAV, even when facing lateral center of gravity shifts. Subsequently, a backstepping control approach is developed to enable autonomous maneuver execution. Simulation results illustrate that the maneuver performance under lateral asymmetry closely resembles that of the symmetric case, demonstrating the effectiveness and need of the proposed control strategy in handling such scenarios.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 A novel apparent power loss based distributed generator siting and sizing method considering dependent loads(Elsevier, 2024-03) Mukherjee, Bijoy K.In the present paper, it is first established that even though the standard Active Power Loss Sensitivity Factor (APLSF) based technique for Renewable Energy based Distributed Generation (REDG) system excels with respect to many available technical assessment indicators, its performance falls short in case of line loss reduction and power transfer capacity improvement indicators. On further investigation through Dynamic Fault Tree Analysis technique, it is found that the unsatisfactory performance of APLSF stem from neglecting reactive power loss and line reactance. Therefore, a novel apparent power loss augmented technique coined as Dynamic Loss Evaluation Indicator (DLEI) method is proposed here. The suitability of the proposed method is validated on IEEE 33 and 85 bus distribution systems for both voltage and voltage and frequency dependent load models and it is shown that the aforementioned indicators are improved along with the other indicators like voltage profile and voltage stability to name a few. For further validation, contingency and power quality analysis are also carried out and improved performance is observed in DLEI method when compared against the APLSF based method.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.Item A Single Loop Dynamic Inversion Control for a Fighter Aircraft Executing Rapid Large Amplitude Maneuvers(IEEE, 2017) Mukherjee, Bijoy K.Modern fighter aircraft undergo rapid and large angular excursions about the body axes in order to execute various complex maneuvers. Such severe flight conditions force the aircraft dynamics to nonlinear regime thereby making nonlinear control implementation almost unavoidable. Such nonlinear controls are usually formulated in inner and outer loops based on the two time scale separation principle. The present paper demonstrates that to perform certain maneuvers, nonlinear control can also be formulated on a single loop without resorting to such a slow-fast separation assumption for the dynamics. To validate the efficacy of the proposed method, nonlinear dynamic inversion controls are designed using this alternate formulation to automatically carry out two very well-known maneuvers cobra and aileron roll maneuver and the corresponding MATLAB simulation results are presented.Item Large Angle Maneuvering with an Asymmetric Aircraft: A Single Loop Control Formulation(ARC, 2018-01) Mukherjee, Bijoy K.Item High Alpha Maneuvering with a Laterally Asymmetric Fighter Aircraft: A Backstepping Control Approach(IEEE, 2020) Mukherjee, Bijoy K.Asymmetric release of payload or partial damage of wing shifts the center-of-gravity (c.g.) of a fighter aircraft to new positions resulting in a highly coupled and nonlinear asymmetric dynamics. Since controlling the aircraft becomes much more challenging when it tries to perform some high alpha maneuver with such lateral asymmetry, implementation of nonlinear control becomes mandatory for the safety of the aircraft. In the present paper, the highly coupled asymmetric dynamics is first converted to the strict feedback form and thereafter a backstepping control is designed to autonomously execute the high alpha cobra maneuver under significant lateral c.g. shift. The simulation results show the maneuver performance under lateral asymmetry to be almost the same as that without any asymmetry.Item Backstepping Control for Asymmetric Fighter Aircraft Executing the High Alpha Herbst Maneuver(IEEE, 2021) Mukherjee, Bijoy K.Asymmetric dynamics of a combat aircraft becomes highly coupled when center-of-gravity (c.g.) of an aircraft shifts to new position because of either partial wing damage or asymmetric release of store. It becomes difficult for an aircraft to execute high angle maneuvering under asymmetric center- of-gravity shift as nonlinearity and dynamics get more complex, under such situation implementation of nonlinear control becomes inevitable. In the present study, dynamics is first converted into strict feedback form and then backstepping control scheme is implemented to execute high alpha herbst maneuver under significant lateral center-of- gravity shift. The simulation result obtained by the present study advocates the maneuver performance under lateral asymmetry to be almost similar as that without any asymmetry.