Tracking the Tracker from its Passive Sonar ML-PDA Estimates

Target motion analysis with wideband passive sonar has received much attention. Maximum likelihood probabilistic data-association (ML-PDA) represents an asymptotically efficient estimator for deterministic target motion, and is especially well-suited for low-observable targets; the results presented here apply to situations with higher signal to noise ratio as well, including of course the situation of a deterministic target observed via clean measurements without false alarms or missed detections. Here we study the inverse problem, namely, how to identify the observing platform (following a two-leg motion model) from the results of the target estimation process, i.e. the estimated target state and the Fisher information matrix, quantities we assume an eavesdropper might intercept. We tackle the problem and we present observability properties, with supporting simulation results.Comment: To appear in IEEE Transactions on Aerospace and Electronic System

Performance Analysis of Bearings-only Tracking Problems for Maneuvering Target and Heterogeneous Sensor Applications

State estimation, i.e. determining the trajectory, of a maneuvering target from noisy measurements collected by a single or multiple passive sensors (e.g. passive sonar and radar) has wide civil and military applications, for example underwater surveillance, air defence, wireless communications, and self-protection of military vehicles. These passive sensors are listening to target emitted signals without emitting signals themselves which give them concealing properties. Tactical scenarios exists where the own position shall not be revealed, e.g. for tracking submarines with passive sonar or tracking an aerial target by means of electro-optic image sensors like infrared sensors. This estimation process is widely known as bearings-only tracking. On the one hand, a challenge is the high degree of nonlinearity in the estimation process caused by the nonlinear relation of angular measurements to the Cartesian state. On the other hand, passive sensors cannot provide direct target location measurements, so bearings-only tracking suffers from poor target trajectory estimation accuracy due to marginal observability from sensor measurements. In order to achieve observability, that means to be able to estimate the complete target state, multiple passive sensor measurements must be fused. The measurements can be recorded spatially distributed by multiple dislocated sensor platforms or temporally distributed by a single, moving sensor platform. Furthermore, an extended case of bearings-only tracking is given if heterogeneous measurements from targets emitting different types of signals, are involved. With this, observability can also be achieved on a single, not necessarily moving platform. In this work, a performance bound for complex motion models, i.e. piecewisely maneuvering targets with unknown maneuver change times, by means of bearings-only measurements from a single, moving sensor platform is derived and an efficient estimator is implemented and analyzed. Furthermore, an observability analysis is carried out for targets emitting acoustic and electromagnetic signals. Here, the different signal propagation velocities can be exploited to ensure observability on a single, not necessarily moving platform. Based on the theoretical performance and observability analyses a distributed fusion system has been realized by means of heterogeneous sensors, which shall detect an event and localize a threat. This is performed by a microphone array to detect sound waves emitted by the threat as well as a radar detector that detects electromagnetic emissions from the threat. Since multiple platforms are involved to provide increased observability and also redundancy against possible breakdowns, a WiFi mobile ad hoc network is used for communications. In order to keep up the network in a breakdown OLSR (optimized link state routing) routing approach is employed

Bearings-only tracking automation for a single unmanned underwater vehicle

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 73-75).Unmanned underwater vehicles have various missions within civilian, military and academic sectors. They have the ability to explore areas unavailable to manned assets and to perform duties that are risky to humans. In particular, UUVs have the ability to perform bearings-only tracking in shallow areas near shorelines. This thesis presents a guidance algorithm for this particular mission. This thesis first presents a Modified Polar Extended Kalman Filter for the estimation problem. Bearings-only tracking is a nonlinear problem that requires some sort of estimator to determine the target state. The guidance algorithm is developed based on the relative positions of the observer and the target. In order to develop the guidance algorithm, the effectiveness of a variety of course maneuvers are presented. The effectiveness of these maneuvers are analyzed both quantitatively and qualitatively. The results from this analysis is incorporated into the final guidance algorithm. This thesis also evaluates the developed guidance algorithm through a series of simulation experiments. The experiments explore a variety of scenarios by varying speed, geometry and acoustic environment. The results of the experiments are analyzed based on estimation errors and detection time. The final conclusions indicate that some of the geometries are more favorable than others. In addition, the degree of noise in the acoustic environment affects the range of the UUV's sensors and the UUV's ability to perform bearings-only tracking for an extended period of time. In addition, the desired speed ratio is one in which the observer is either the same speed as or slower than the target.by Danica Lee Middlebrook.S.M

Pistage 3D par mesures angulaires sans manœuvres

International audiencePassive target estimation is a widely investigated problem of practical interest. We are concerned specifically with an autonomous flight system developed onboard the ONERA ReSSAC unmanned helicopter. This helicopter is equipped with a (visible or infrared) camera and so is able to measure azimuths and elevation angles of a target. The latter is supposed to follow a constant velocity motion. It is well known that observer must maneuver in order to insure the observability of the target state. We are interested in tracking partly the target state when both the observer and the target have a constant velocity model in a three-dimensional space. We describe the set of all the trajectories compatible with the angle measurements and we propose a quick method to estimate these trajectories.Le pistage passif d'une cible est un domaine de recherche actif. Nous nous intéressons particulièrement au drone hélicoptère Ressac. Celui-ci est équipé d'une caméra optique et infrarouge. Il est donc capable d'effectuer des mesures angulaires (azimuts et sites) d'une cible. Cette cible est supposée suivre une mouvement rectiligne uniforme dans l'espace. Il est bien connu que l'observateur doit manœuvrer pour pour assurer l'observabilité de l'état de la cible. Dans ce papier, nous estimons partiellement cet état lorsque la cible et l'observateur sont en mouvement rectiligne uniforme dans l'espace 3D. Nous décrivons l'ensemble des trajectoires cible compatibles avec ces mesures angulaires et nous proposons une méthode rapide d'estimations de ces trajectoires

IMPROVED NON-LINEAR SIGNAL ESTIMATION TECHNIQUE FOR UNDERSEA SONAR BASED NAVAL APPLICATIONS

The aim of this work is to develop passive target tracking algorithm, suitable for implementation in target motion analysis for underwater applications. The vehicle is assumed to be standstill in underwater watching for any target ship using bearings only measurements. Using these measurements, the algorithm calculates the course of the target, which is further used to find out target range and speed. Provision is given to generate range and course if the speed of the target is known by some other means. Pseudo Linear Estimator (PLE) is developed to reduce the noise in the measurements and to find out target motion parameters. Though PLE offers a biased estimate in certain scenarios, it has an advantage as it hardly diverges. It offers the features of Kalman filter viz., sequential processing, flexibility to adopt the variance of each measurement etc.  The Monte-Carlo simulation results are presented for a typical scenario and it is shown that this algorithm is useful for naval underwater applications.Â

Performance Analysis of Extended Kalman filter and Unscented Kalman filter for Doppler Bearing Passive Target Tracking

Abstract-Conventional passive bearing together with Doppler measurements is explored in Target motion analysis (TMA). This Doppler bearing tracking (DBT) approach offers one advantage compared to bearings-only tracking, that DBT does not require ownship maneuver. By using EKF and unscented Kalman filter (UKF), the target motion analysis is carried out. To obtain the convergence of the estimation fast the inclusion of range and bearing parameters is proposed in the target state vector. Doppler shifts are experienced by the harmonic signals at the ownship so that the frequency measurements can be explored to improve estimation accuracy. This paper deals with the performance evaluation of both EKF and UKF for under water tracking applications and the results for DBT are compared between extended Kalman filter and Doppler-bearing passive target tracking using unscented Kalman filter Monte Carlo simulations

Trajectographie Passive sans manœuvre de l'observateur

Les méthodes de trajectographie conventionnelles par mesures d angle supposent que la source est en mouvement rectiligne uniforme tandis que l observateur est manœuvrant. Dans cette thèse, nous remettons en cause cette hypothèse en proposant un autre modèle de cinématique de la source : le mouvement circulaire uniforme. Nous prouvons qu une telle trajectoire est observable à partir d un observateur en mouvement rectiligne uniforme. Puis, nous étudions l apport de mesures additionnelles de fréquence ou la faisabilité de la trajectographie par mesures de distances. Le cas d une source en mouvement rectiligne uniforme et d un observateur manœuvrant est étudié pour ce dernier type de mesures. Chaque cas donne lieu à une analyse de l observabilité de la trajectoire de la source et à la mise au point de l estimateur du maximum de vraisemblance. Nous montrons que ce dernier s avère le plus souvent efficace.The conventional bearings-only target motion analysis methods assume that the source is in constant velocity motion (constant speed and heading) while the observer maneuvers. In this thesis, we reassess this hypothesis and propose another model of the kinematics of the source: the constant turn motion (an arc of circle followed at constant speed). We prove that this kind of trajectory is observable by an observer in constant velocity motion. Then, we study the contribution of the addition of frequency measurements or the feasibility of target motion analysis methods that use range only measurements. The case of a source in constant velocity motion with a maneuvering observer is examined for this last type of measurements. Each case leads to an analysis of the observability of the trajectory of the source and to the development of the associated maximum likelihood estimator. We show that this estimator often appears to be efficient.TOULON-Bibliotheque electronique (830629901) / SudocSudocFranceF

Control of aircraft in the terminal manoeuvring area using parallelised sequential Monte Carlo

This paper reports on the use of a parallelised Model Predictive Control, Sequential Monte Carlo algorithm for solving the problem of conflict resolution and aircraft trajectory control in air traffic management specifically around the terminal manoeuvring area of an airport. The target problem is nonlinear, highly constrained, non-convex and uses a single decision-maker with multiple aircraft. The implementation includes a spatio-temporal wind model and rolling window simulations for realistic ongoing scenarios. The method is capable of handling arriving and departing aircraft simultaneously including some with very low fuel remaining. A novel flow field is proposed to smooth the approach trajectories for arriving aircraft and all trajectories are planned in three dimensions. Massive parallelisation of the algorithm allows solution speeds to approach those required for real-time use.This work was supported by EPSRC (Engineering and Physical Sciences Research Council - UK) Grant No. EP/G066477/1AIAA Conference on Guidance, Navigation and Control 201

Angles-Only Navigation for Autonomous Orbital Rendezvous

The proposed thesis of this dissertation has both a practical element and theoretical component which aim to answer key questions related to the use of angles-only navigation for autonomous orbital rendezvous. The first and fundamental principle to this work argues that an angles-only navigation filter can determine the relative position and orientation (pose) between two spacecraft to perform the necessary maneuvers and close proximity operations for autonomous orbital rendezvous. Second, the implementation of angles-only navigation for on-orbit applications is looked upon with skeptical eyes because of its perceived limitation of determining the relative range between two vehicles. This assumed, yet little understood subtlety can be formally characterized with a closed-form analytical observability criteria which specifies the necessary and sufficient conditions for determining the relative position and velocity with only angular measurements. With a mathematical expression of the observability criteria, it can be used to 1) identify the orbital rendezvous trajectories and maneuvers that ensure the relative position and velocity are observable for angles-only navigation, 2) quantify the degree or level of observability and 3) compute optimal maneuvers that maximize observability. In summary, the objective of this dissertation is to provide both a practical and theoretical foundation for the advancement of autonomous orbital rendezvous through the use of angles-only navigation