Browsing by Author "Lee, Seokwon"

Now showing 1 - 11 of 11
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    Analysis of guidance laws with non-monotonic line-of-sight rate convergence
    (IEEE, 2021-09-20) Lee, Seokwon; Cho, Namhoon; Shin, Hyosang
    This study presents analyses of guidance laws that involve non-monotonic convergence in heading error from a new perspective based on an advanced stability concept. Pure proportional navigation with range-varying navigation gain is considered, and the gain condition to guarantee asymptotic convergence to the collision course is investigated while allowing the heading error to exhibit patterns that involve intermediate diversion. The extended stability criterion considered in this study allows local increase of the function in some finite intervals, which is less conservative than the standard stability theorem. The existing guidance laws involving intentional modulation of the heading error as well as the design of the navigation gain are discussed with respect to the new stability criterion.
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    Analysis of rendezvous guidance laws for autonomous aerial refueling for non-maneuvering and identical speed targets
    (Elsevier, 2022-01-14) Lee, Seokwon; Kim, Mingu
    This study analyzes rendezvous guidance schemes for UAVs refueling. Assuming the target is non-maneuvering with identical speed, a necessary condition is investigated for the UAV to approach the rendezvous point. Three types of guidance laws are considered to analyze the performance under the condition. A reachable region is analytically obtained using the closed-form solution of the deviated pursuit and pure proportional navigation. Numerical simulation demonstrates the analyzed result for the rendezvous mission.
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    Analytic approach to impact time guidance with look angle constraint using exact time-to-go solution
    (American Society of Civil Engineers, 2023-12-12) Lee, Seokwon; Kim, Jinrae; Kim, Youdan; Cho, Namhoon
    This paper proposes an analytic approach for impact time control guidance laws against stationary targets using biased proportional navigation. The proposed guidance scheme realizes the impact time control in two different ways: the first approach directly uses the exact time-to-go error to satisfy both the impact time control and the field-of-view constraint, while the second approach adopts a look angle tracking law to indirectly control the impact time, with the reference profile of the look angle generated using the exact time-to-go solution. The stability properties of the proposed guidance laws are discussed, and numerical simulations are carried out to evaluate their performance in terms of accuracy and efficiency.
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    Data-driven capturability analysis for pure proportional navigation guidance considering target maneuver
    (Springer, 2021-06-15) Lee, Suwon; Lee, Youngjun; Lee, Seokwon; Kim, Youdan; Han, Yongsu; Park, Jangseong
    A data-driven statistical analysis of the missile’s capture region is performed. The capture region is the region of the initial geometric configuration for pursuer missile against a target in which the missile can intercept the target while satisfying specific constraints. The statistical verification approach has advantages over the analytic approach in that it can deal with various guidance algorithms and target maneuver utilizing numerical simulator. In this study, the verification model is constructed using the Gaussian process regression model. The verification model computes the probability distribution of the target capture over the initial configuration space. The data-driven capturability analysis is conducted for the maneuvering target using the Gaussian process regression model. The capture region derived from the statistical model is compared with the analytic model, and the effectiveness of the active sampling algorithm is demonstrated.
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    Destination and time-series inference of moving objects via conditionally Markov process
    (Springer, 2024-10) Lee, Seokwon; Shin, Hyo-Sang
    This paper presents a destination and time-series inference algorithm for tracking moving targets. The destination of the object is considered the intent, and inference and state estimation are performed in the Bayesian framework. To describe the destination-aware target motion, we construct the state transition model using a conditionally Markov process. We introduce a multiple model to achieve simultaneous intent and time-series inferences. Given finite destination candidates, the maximum a posteriori hypothesis is chosen as the destination. For time-series inference, local estimates obtained from Kalman filters are fused to yield target state estimates. To address unspecified terminal conditions, the proposed algorithm incorporates parameter correction techniques based on relative geometry. Numerical simulations are performed to validate the proposed inference algorithm.
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    Generalized analysis of biased proportional navigation guidance with fractional power error feedback
    (AIAA, 2022-06-03) Cho, Namhoon; Kim, Jinrae; Lee, Seokwon; Kim, Youdan
    This study presents a comprehensive analysis of biased proportional navigation guidance laws with variable gain in the bias command that achieve stationary target interception with a desired impact angle under the restriction of permissible look angle. More specifically, this study investigates the bias shaping approach, which takes the bias gain function given by a product of factors in range and look angle. The linear feedback and fractional power feedback of impact-angle error are considered for command structures. For each command form, this study examines the conditions that should be satisfied by the gain functions to guarantee mission accomplishment without violation of the constraints. The analysis particularly focuses on estimating the set of feasible initial or final conditions that ensure compliance with the constraints along the trajectory. Numerical simulation is performed for a range of initial and final flight-path angles to verify the analytical results. The findings of this study provide a general foundation for the design of a nonswitching guidance law for impact-angle control with limited look angle through shaping of gain profiles.
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    Impact analysis of time synchronization error in airborne target tracking using a heterogeneous sensor network
    (MDPI, 2024-04-23) Lee, Seokwon; Yuan, Zongjian; Petrunin, Ivan; Shin, Hyosang
    This paper investigates the influence of time synchronization on sensor fusion and target tracking. As a benchmark, we design a target tracking system based on track-to-track fusion architecture. Heterogeneous sensors detect targets and transmit measurements through a communication network, while local tracking and track fusion are performed in the fusion center to integrate measurements from these sensors into a fused track. The time synchronization error is mathematically modeled, and local time is biased from the reference clock during the holdover phase. The influence of the time synchronization error on target tracking system components such as local association, filtering, and track fusion is discussed. The results demonstrate that an increase in the time synchronization error leads to deteriorating association and filtering performance. In addition, the results of the simulation study validate the impact of the time synchronization error on the sensor network.
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    Intent-informed state estimation for tracking guided targets
    (Elsevier, 2023-11-16) Lee, Seokwon; Shin, Hyosang; Tsourdos, Antonios
    This paper proposes a state estimation and prediction for tracking guided targets using intent information. A conditionally Markov process is used to describe the destination-oriented target motion, and the collision intent is incorporated through the zero-effort-miss guidance information. The expected arrival time necessary for the conditionally Markov model is determined through the collision geometry and destination motion. Finally, the Kalman filter technique is used to estimate and predict the target state. Numerical simulations demonstrate that the proposed approach can improve state estimation accuracy in both static and dynamic destination cases.
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    Inverse optimality of pure proportional navigation guidance for stationary targets
    (American Institute of Aeronautics and Astronautics, 2021-07-21) Lee, Seokwon; Cho, Namhoon
    The main contribution of this study is the optimality analysis of the PPNG performed in full generality. The new theoretical findings can explain the result of the former analysis in which the PPNG is derived as the minimum effort solution [5] and also describe a comprehensive design framework including the observability-enhanced guidance laws developed for the dual homing guidance problem. Furthermore, this study provides several examples illustrating how the PPNG with various navigation gain functions can be understood as optimal control solutions.
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    Look-angle-constrained control of arrival time with exact knowledge of time-to-go
    (AIAA, 2021-05-26) Cho, Namhoon; Lee, Seokwon
    The capability to control the time of arrival at a goal position as desired endows a single vehicle or a coalition of many of them with the strategic advantage to perform time-critical missions. Arrival time coordination can be used as an element to solve multi-agent, multidepot routing and task planning problems in cooperative unmanned aerial robots. The tactic known as Salvo, which either designates or synchronizes the impact times across multiple missiles to enhance their collective survivability as well as attack effectiveness, strongly depends on control of arrival time. In principle, control of arrival time is essentially adjustment of the arc length of the vehicle’s flight path through manipulation of the curvature, provided that most vehicles flying in the atmosphere often prefer not to change their speeds excessively. On the other hand, the capability to take measurements of the target with onboard sensors provides a higher degree of autonomy to the vehicle and hence allows a more intelligent behavior. Modern autonomous vehicles acquire information about the designated destination or the surrounding environment with imaging sensors, in particular. An onboard sensor that collects emission or reflection from the target is usually not likely to be omni-directional yet possesses only a finite field-of-regard. The requirement to ensure continuous acquisition of target-originated signals necessitates a measure to keep the information source inside the sensor’s field of view that spans over a solid angle of limited range. That is, a box constraint is imposed on the look angle.
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    Three-dimensional biased proportional navigation guidance based on spatial rotation of predicted final velocity
    (IEEE, 2022-08-17) Cho, Namhoon; Lee, Seokwon; Shin, Hyosang; Kim, Tae-Hun
    This study presents the design of three-dimensional biased proportional navigation guidance laws for arrival at a stationary target along a desired direction based on spatial rotation of predicted final velocity vector. The focus is on full constructive derivation using vector-form expressions without introducing local representation of rotation such as Euler angles or quaternions. The proposed approach synthesises the bias command in the form of an angular velocity vector through realisation of the predictive control design philosophy, the direction which has been unexplored in a three-dimensional setting. The proposed approach avoids heuristic choices and approximations in the design process and hence overcomes the limitation of earlier studies. The vector-form design approach provides theoretical and practical advantages including rigour in derivation, clear geometric understandings about the problem provided by identification of the most effective direction for rotation of final velocity, independence from selection of a fixed coordinate system, avoidance of singularities in local representations, more direct trajectory shaping, and simple implementation.