BITS Faculty Publications
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Item Multi-Objective MDP-Based Routing in UAV Networks for Search-Based Operations(IEEE, 2024-05) Chalapathi, G.S.S.; Chamola, VinayUnmanned aerial vehicle (UAV) systems have gained widespread recognition due to their versatility and autonomy. Their deployment for disaster mitigation and management operations is seen as one of their most important applications over the past decade. In such UAV networks, routing plays a crucial role in determining network performance parameters such as network lifetime, data transmission latency, and packet delivery ratio. This paper presents a novel routing mechanism - Multi-Objective Markov Decision Based Routing (MOBMDP) for UAV networks carrying out search-based operations. MOBMDP models routing decisions in a Markov Decision Process (MDP) framework and uses Q-learning to take decisions. It compares routing paths using three metrics, viz., Remaining Energy of the Minimum Energy Node (REMEN), Power Distance ratio (PD), and Expected Delay (ED). Amongst these metrics, PD is a novel metric proposed by this work. PD simultaneously optimizes the energy efficiency and energy distribution in the network. Further, MOBMDP uses a novel reinforcement learning inspired method to estimate transmission delay in a given path. Intensive simulation studies compare MOBMDP to four state-of-the-art routing protocols. Results show a significant improvement in network lifetime, packet delivery ratio, energy efficiency, average data transmission delay, and error in delay estimation.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 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 Adaptive block backstepping control for a UAV performing lateral maneuvers under lateral c.g. uncertainty(Emerald, 2022-03) Mukherjee, Bijoy KrishnaUnmanned aerial vehicles (UAVs) have wide applications in surveillance and reconnaissance without risking human life. Due to unbalanced payload distribution or in-flight deployment, UAVs may undergo lateral center of gravity (c.g.) variations resulting in an asymmetric dynamic having significant longitudinal and lateral/directional coupling and hence more pronounced nonlinearity. Therefore, automatic control of UAVs becomes extremely difficult when it is forced to perform maneuvers under such imbalance in lateral mass distribution. The purpose of this paper is to design adaptive nonlinear control so that the UAV can perform some useful lateral/directional maneuver under lateral c.g. uncertainty.Item A Comprehensive Review of Unmanned Aerial Vehicle Attacks and Neutralization Techniques(Elsevier, 2021-02) Gupta, Navneet; Chamola, VinayUnmanned Aerial Vehicles (UAV) have revolutionized the aircraft industry in this decade. UAVs are now capable of carrying out remote sensing, remote monitoring, courier delivery, and a lot more. A lot of research is happening on making UAVs more robust using energy harvesting techniques to have a better battery lifetime, network performance and to secure against attackers. UAV networks are many times used for unmanned missions. There have been many attacks on civilian, military, and industrial targets that were carried out using remotely controlled or automated UAVs. This continued misuse has led to research in preventing unauthorized UAVs from causing damage to life and property. In this paper, we present a literature review of UAVs, UAV attacks, and their prevention using anti-UAV techniques. We first discuss the different types of UAVs, the regulatory laws for UAV activities, their use cases, recreational, and military UAV incidents. After understanding their operation, various techniques for monitoring and preventing UAV attacks are described along with case studies.