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Efficient Aimpoint Tracking using Target Range Profiles of a Wideband FMCW Seeker
나원상,황익호,신효상,Antonios Tsourdos 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4
This paper proposes an efficient aimpoint tracking filter for high-range resolution FMCW radar seekers. A modified probabilistic data association scheme is devised to deal with closely located measurements generatedby scatterers of an extended target and multipath clutter. In order to discriminate the aimpoint measurement fromothers, an approximate target range profile is used for calculating likelihoods of the validated measurements. Simulationresults show the effectiveness and the superior performance of the proposed approach.
Neural-networks-based Adaptive Control for an Uncertain Nonlinear System with Asymptotic Stability
신종호,김승균,Antonios Tsourdos 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4
This paper proposes a neural-networks(NN)-based adaptive controller for an uncertain nonlinear system with asymptotic stability. While the satisfactory performance of the NN-based adaptive controller is validated well in various uncertain nonlinear systems, the stability is commonly restricted to the uniformly ultimate boundedness( UUB). To improve the UUB of the NN-based adaptive control to the asymptotically stability(AS) with continuous control, the existing NN-based adaptive controller is augmented with a robust-integral-signum-error (RISE) feedback term, and overall closed-loop stability is rigorously analyzed by modifying the typical stability analysis for the RISE feedback control. To demonstrate the effectiveness of the proposed controller, numerical simulations for a fault tolerant flight control with a nonlinear F-16 aircraft model are performed.
Earliest Intercept Geometry Guidance to Improve Mid-Course Guidance in Area Air-Defence
Shin, Hyo-Sang,Tahk, Min-Jea,Tsourdos, A.,White, B.A. The Korean Society for Aeronautical and Space Scie 2010 International Journal of Aeronautical and Space Sc Vol.11 No.2
This paper describes a mid-course guidance strategy based on the earliest intercept geometry (EIG) guidance. An analytical solution and performance validation will be addressed for generalized mid-course guidance problems in area air-defence in order to improve reachability and performance. The EIG is generated for a wide range of possible manoeuvres of the challenging missile based on the guidance algorithm using differential geometry concepts. The main idea is that a mid-course guidance law can defend the area as long as it assures that the depending area and objects are always within the defended area defined by EIG. The velocity of Intercept Point in EIG is analytically derived to control the Intercept Geometry and the defended area. The proposed method can be applied in deciding a missile launch window and launch point for the launch phase.
Coordinated standoff tracking of moving target groups using multiple UAVs
Hyondong Oh,Seungkeun Kim,Hyo-sang Shin,Tsourdos, Antonios IEEE 2015 IEEE transactions on aerospace and electronic syst Vol.51 No.2
<P>This paper presents a methodology for coordinated standoff tracking of moving target groups using multiple unmanned aerial vehicles (UAVs). The vector field guidance approach for a single UAV is first applied to track a group of targets by defining a variable standoff orbit to be followed, which can keep all targets within the field-of-view of the UAV. A new feedforward term is included in the guidance command considering variable standoff distance, and the convergence of the vector field to the standoff orbit is analyzed and enhanced by adjusting radial velocity using two active measures associated with vector field generation. Moreover, for multiple group tracking by multiple UAVs, a two-phase approach is proposed as a suboptimal solution for a Non-deterministic Polynomial-time hard (NP-hard) problem, consisting of target clustering/assignment and cooperative standoff group tracking with online local replanning. Lastly, localization sensitivity to the group of targets is investigated for different angular separations between UAVs and sensing configurations. Numerical simulations are performed using randomly moving ground vehicles with multiple UAVs to verify the feasibility and benefit of the proposed approach.</P>
Collision Avoidance Strategies for Unmanned Aerial Vehicles in Formation Flight
Seo, Joongbo,Kim, Youdan,Kim, Seungkeun,Tsourdos, Antonios IEEE 2017 IEEE transactions on aerospace and electronic syst Vol.53 No.6
<P>Collision avoidance strategies for multiple unmanned aerial vehicles (UAVs) based on geometry are investigated in this study. The proposed strategies allow a group of UAVs to avoid obstacles and separate if necessary through a simple algorithm with low computation by expanding the collision-cone approach to formation of UAVs. The geometric approach uses line-of-sight vectors and relative velocity vectors where dynamic constraints are included in the formation. Each UAV can determine which plane and direction are available for collision avoidance. An analysis is performed to define an envelope for collision avoidance, where angular rate limits and obstacle detection range limits are considered. Based on the collision avoidance envelope, each UAV in a formation determines whether the formation can be maintained or not while avoiding obstacles. Numerical simulations are performed to demonstrate the performance of the proposed strategies.</P>
Consensus-based reconfigurable controller design for unmanned aerial vehicle formation flight
Seo, J,Kim, Y,Kim, S,Tsourdos, A SAGE Publications 2012 Proceedings of the Institution of Mechanical Engin Vol.226 No.7
<P>This article presents a distributed controller design methodology with a failure detection logic for formation flight of unmanned aerial vehicles (UAVs). An output feedback linearization method with a consensus protocol is used to maintain a specified time-varying geometric configuration of multiple UAVs. In this approach, any explicit leader does not exist in the team, and the control strategy requires only the local neighbour-to-neighbour information between the vehicles. A graph Laplacian matrix is used to define the information flow topologies between the vehicles. The Failure detection algorithm is also proposed in order to detect a communication loss or an aircraft system fault and to isolate the failed one. The detection logic proposed in this study considers the case in which one of the vehicles totally broke down. Once the failure is detected, the failed vehicle is isolated. Reforming the interconnection topology using the failure detection logic can guarantee the stable formation flight with the proposed controller. Numerical simulations are performed to validate the performance of the proposed controller with which the formation geometry is dynamically reconfigured using failure detection information.</P>
Composite Model Reference Adaptive Control with Parameter Convergence Under Finite Excitation
Cho, Namhoon,Shin, Hyo-Sang,Kim, Youdan,Tsourdos, Antonios Institute of Electrical and Electronics Engineers 2018 IEEE transactions on automatic control Vol.63 No.3
<P>A new parameter estimation method is proposed in the framework of composite model reference adaptive control for improved parameter convergence without persistent excitation. The regressor filtering scheme is adopted to perform the parameter estimation with signals that can be obtained easily. A new framework for residual signal construction is proposed. The incoming data are first accumulated to build the information matrix, and then its quality is evaluated with respect to a chosen measure to select and store the best one. The information matrix is built to have full rank after sufficient but not persistent excitation. In this way, the exponential convergence of both tracking error and parameter estimation error can be guaranteed without persistent oscillation in the external command, which drives the system. Numerical simulations are performed to verify the theoretical findings and to demonstrate the advantages of the proposed adaptation law over the standard direct adaptation law.</P>
Earliest Intercept Geometry Guidance to Improve Mid-Course Guidance in Area Air-Defence
Hyo-Sang Shin,Min-Jea Tahk,A. Tsourdos,B. A. White 한국항공우주학회 2010 International Journal of Aeronautical and Space Sc Vol.11 No.2
This paper describes a mid-course guidance strategy based on the earliest intercept geometry (EIG) guidance. An analytical solution and performance validation will be addressed for generalized mid-course guidance problems in area air-defence in order to improve reachability and performance. The EIG is generated for a wide range of possible manoeuvres of the challenging missile based on the guidance algorithm using differential geometry concepts. The main idea is that a mid-course guidance law can defend the area as long as it assures that the depending area and objects are always within the defended area defined by EIG. The velocity of Intercept Point in EIG is analytically derived to control the Intercept Geometry and the defended area. The proposed method can be applied in deciding a missile launch window and launch point for the launch phase.