Beacon Location Research Articles

Comparative study on the effect of Parameter Mapping Sonification on perceived instabilities, efficiency, and accuracy in real-time interactive exploration of noisy data streams

This paper presents a comparative study on common Parameter Mapping Sonifications (PMSons) designed to reduce the perception of instabilities during the real-time interactive exploration of noisy data streams. The objective of this study is to evaluate the capacity of these PMSons in reducing the perceived fluctuations while preserving both efficiency and accuracy of participants’ estimations during the exploration task. Based on the real application of beacon localization for rescue operations, an abstraction of the task was developed which simulates the basic concepts involved, i.e. the estimation of local maxima during the exploration of a 1D data topography. Three different PMSons were selected, based on pitch, pitch averaged over time, and tempo, evaluated for three different noise levels applied to the data. Subjects explored the auditory graph using a pen tablet to define their auditory viewpoint (i.e. position) on the topography. Evaluations were based on subjects’ ability to quickly appraise the underlying data topography along with aesthetic considerations regarding the impact of noise on the exploration task. Results showed that both tempo and pitch averaged PMSon reduced the perceived instabilities compared to pitch, while tempo preserved the response time of the sonification feedback.

Efficient Distributed Localization Algorithm for Wireless Sensor Networks

Background: WSN covers a wide spectrum of military and hospital monitoring, military surveillance, fire and intruder detection and animal tracking. Objective: Among the various applications mentioned above, WSN plays a vital role in Internet of Things (IoT). It allows us to develop an intelligent system when there is a dynamic change in the environment. Results: It is shown that the localization error of the proposed system is less than the existing system. So it is a precise efficient localization for WSN. Conclusion: The proposed WSN uses distributed, RSS based and mobile beacon localization algorithm which gives relatively high precision. It can be used in a dynamic environment. It can reduce the energy consumption and also localization error.

Omnidirectional beacon-localization using a catadioptric system.

We present a catadioptric beacon localization system that can provide mobile network nodes with omnidirectional situational awareness of neighboring nodes. In this system, a receiver composed of a hyperboloidal mirror and camera is used to estimate the azimuth, elevation, and range of an LED beacon. We provide a general framework for understanding the propagation of error in the angle-of-arrival estimation and then present an experimental realization of such a system. The situational awareness provided by the proposed system can enable the alignment of communication nodes in an optical wireless network, which may be particularly useful in addressing RF-denied environments.

Location Privacy using Anonymous Beacon in Vehicular Ad Hoc Networks

Vehicular Ad hoc Network (VANET) plays a significant role in safety communication and commercial applications. Applications necessitate to track the location of vehicles, have a strong impact on location privacy and security. Ensuring the correctness of location information is essential without it being disclosed to other vehicles. Conventionally, a privacy preservation mechanism disseminates anonymous beacons for providing location based services to the vehicles and it is verified by the Location Server (LS). In VANET, it is crucial to develop a technique that provides security and privacy with minimum overhead. This study proposes a lightweight mechanism called as Preservation of Location Privacy through Anonymous Beacon (PLPAB) that provides location-based services to the users in a secured manner. Initially at the time of registration, a vehicle receives a triplet from LS. The triplet has a short term symmetric key for beacon encryption and decryption and it generates two random integers to evaluate mysterious time-dependent value shared between LS and vehicle. PLPAB includes two mechanisms such as anonymous beacon generation and location verification. In beacon generation, the vehicles broadcast an anonymous beacon at a specific interval for providing the secure location information. Instead of generating the beacon at all the time, it enables a vehicle to generate a beacon adapting to its mobility. Thus, it reduces unnecessary beacon generation, resulting in less overhead. In location verification, LS verifies the claimed location in the beacon by determining the inference of location using signal strength and speed of the beacon originator. The simulation results show that the PLPAB system achieves and preserves a higher level of location privacy on vehicles and is more resilient to attacks when compared to the existing A-VIP scheme.

Range-Based Underwater Vehicle Localization in the Presence of Unknown Ocean Currents: Theory and Experiments

This paper addresses the problem of range-based autonomous underwater vehicle (AUV) localization in the presence of unknown ocean currents. In the setup adopted, the AUV is equipped with an attitude and heading reference system, a depth sensor, and an acoustic device that provides measurements of its distance to a set of stationary beacons. We consider the situation where the number of active beacons is not known in advance and may vary with time. The objective is to simultaneously localize the AUV and beacons, that is, to find their positions underwater. We start by deriving conditions under which it is possible to reconstruct the initial condition of the system under study. We consider the design model where the states evolve continuously with time, but the range measurements are only available at discrete instants of time, possibly in a nonuniform manner. For trimming maneuvers that correspond to AUV trajectories with constant linear and angular velocities expressed in the body frame, we show that if either the position of one of the beacons or the initial position of the AUV is known, then even without depth information the system is weakly observable (i.e., the set of states that are indistinguishable from a given initial configuration contains only a set of finite isolated points). If depth measurements are also available, then the system is observable even in the presence of unknown constant ocean currents. Equipped with these results, we then propose a novel observer for simultaneous AUV and beacon localization. The mathematical setup exploited borrows from minimum-energy estimation theory applied to continuous-time processes with discrete measurements, projection filters, and multiple-model estimation techniques. Convergence analysis of the resulting observer system yields conditions under which the estimation errors converge to a small neighborhood of the origin (whose size depends on the magnitude of the process and measurement noise). The results of field experiments with a robotic marine vehicle show the efficacy of the simultaneous AUV/multiple beacon localization system proposed.

Wearable self‐tuning antenna for emergency rescue operations

In this study, the design, hardware implementation and characterisation of a self-tuning 406 MHz antenna of a Cospas-Sarsat personal locator beacon are presented. The realised prototype is able to perform automatic tuning of the antenna under time-varying environmental conditions due to human body movements and sea water proximity. The impedance tuning is performed by tracking the instantaneous value of the reflection coefficient and by modifying an appropriate impedance matching network according to a real-time adaptive algorithm. A resilient default/backup software architecture has been designed to ensure that tuning guarantees a return loss higher than 10 dB for the personal locator beacon in most of impedance mismatching conditions.

An Efficient Node Localization Approach with RSSI for Randomly Deployed Wireless Sensor Networks

An efficient path planning approach in mobile beacon localization for the randomly deployed wireless sensor nodes is proposed in this paper. Firstly, in order to improve localization accuracy, the weighting function based on the distance between nodes is constructed. Moreover, an iterative multilateration algorithm is also presented to avoid decreasing the localization accuracy. Furthermore, a path planning algorithm based on grid scan which can traverse entirely in sensor field is described. At the same time, the start conditions of localization algorithm are also proposed to improve localization accuracy. To evaluate the proposed path planning algorithm, the localization results of beacon nodes randomly deployed in sensor field are also provided. The proposed approach can provide the deployment uniformly of virtual beacon nodes among the sensor fields and the lower computational complexity of path planning compared with method which utilizes only mobile beacons on the basis of a random movement. The performance evaluation shows that the proposed approach can reduce the beacon movement distance and the number of virtual mobile beacon nodes by comparison with other methods.

Optimal pinging frequencies in the search for an immobile beacon

ABSTRACTWe consider a search for an immobile object that can only be detected if the searcher is within a given range of the object during one of a finite number of instantaneous detection opportunities; i.e., “pings.” More specifically, motivated by naval searches for battery-powered flight data recorders of missing aircraft, we consider the trade-off between the frequency of pings for an underwater locator beacon and the duration of the search. First, assuming that the search speed is known, we formulate a mathematical model to determine the pinging period that maximizes the probability that the searcher detects the beacon before it stops pinging. Next, we consider generalizations to discrete search speed distributions under a uniform beacon location distribution. Lastly, we present a case study based on the search for Malaysia Airlines Flight 370 that suggests that the industry-standard beacon pinging period—roughly 1 second between pings—is too short.

IMPROVING DETECTION TECHNIQUE FOR FLIGHT RECORDERS OF THE DISTRESS AIRPLANES CRASHED INTO OCEAN BY INTEGRATING INERTIAL NAVIGATION SYSTEM INTO UNDERWATER LOCATOR BEACON

Flight recorder, used to analyze distress reasons, is equipped with underwater locator beacon (ULB) for being detected and recovered easily in sea. According to the recovery report for the Air France flight no. AF447 distress airplane, it nearly took two years and cost 40 million US dollars to search and recover the flight recorders. Apparently, future aviation safety could be greatly improved if earlier recovery of the flight recorders would reveal the crash reasons sooner. Therefore, this paper is aimed to develop an enhanced ULB, which integrates inexpensive inertial navigation system (INS) into ULB, for a cost-effective and time-saving operation of search and recovery in the future. This new equipment is anticipated to directly provide the location of flight recorders to the search and recovery authority. From the static and dynamic tests, maximum position errors are below 50 m when the standalone INS operates in a duty cycle of 78 seconds. From the case report of AF447 aircraft crush, the time taken from 38,000 feet (=11,582 m) descent to sea level is about 3 minutes and 30 seconds. Over this time frame, the maximum position error is about 140 m owing to the nearly linear drift property of the INS. Thus, the proposed INS-aided ULB approach should be feasible to the search and recovery mission.

Tracking Human Mobility Using WiFi Signals.

We study six months of human mobility data, including WiFi and GPS traces recorded with high temporal resolution, and find that time series of WiFi scans contain a strong latent location signal. In fact, due to inherent stability and low entropy of human mobility, it is possible to assign location to WiFi access points based on a very small number of GPS samples and then use these access points as location beacons. Using just one GPS observation per day per person allows us to estimate the location of, and subsequently use, WiFi access points to account for 80% of mobility across a population. These results reveal a great opportunity for using ubiquitous WiFi routers for high-resolution outdoor positioning, but also significant privacy implications of such side-channel location tracking.

Guoguo: Enabling Fine-Grained Smartphone Localization via Acoustic Anchors

Modern smartphones and location-based services and apps are poised to transform our daily life. However, current smartphone-based localization solutions are limited mainly to outdoor, mostly missing practical, robust and accurate indoor location solutions. Despite significant efforts on indoor localization in both academia and industry in the past two decades, highly accurate and practical smartphone-based indoor localization remains an open problem. To enable indoor location-based services (ILBS), e.g., step-by-step navigation for the Blind and visually impaired, there are several stringent requirements: highly accurate (foot-level); no additional hardware components or extensions on users’ smartphones; scalable to massive concurrent users. Current GPS, Radio RSS (e.g. Wi-Fi, Bluetooth, ZigBee), or Fingerprinting based solutions can only achieve meter-level or room-level accuracy. In this paper, we propose a practical and accurate solution that fills the long-lasting gap of smartphone-based fine-grained indoor localization. Specifically, we design and implement an indoor localization ecosystem Guoguo. Guoguo consists of an anchor network with a coordination protocol to transmit modulated localization beacons using high-band acoustic signals, a realtime processing app in a smartphone, and a backend server for indoor contexts and location-based services. We further propose approaches to improve its coverage, accuracy, and location update rate with low-power consumption. Our prototype shows centimeter-level localization accuracy in several typical indoor environments. Such precise indoor localization is expected to have high impact in the future ILBS and our daily activities.

Cellphone geolocation via magnetic mapping

We develop novel algorithms based on interval analysis with theoretical guarantees, to augment the accuracy of cell phone geolocation by taking advantage of local variations of magnetic intensity. Thus, the sources of disturbances to magnetometer readings caused indoors are effectively used as beacons for localization. We construct a magnetic intensity map for an indoor environment by collecting magnetic field data over each floor tile. We then test the algorithms without position initialization and obtain indoor geolocation to within 2 m while slowly walking over a complex path of 80 m. The geolocation errors are smaller in the vicinity of large magnetic disturbances. Finally, we fuse the magnetometer measurement with inertial measurements on the cell phone to yield even smaller geolocation errors of under 50 cm for a moving user. Our theoretical results connect geolocation accuracy to combinations of sensor and map properties.

DOA-Based Endoscopy Capsule Localization and Orientation Estimation via Unscented Kalman Filter

The endoscopy capsule is a medical device capable of capturing images inside human's digestion system, specifically the small and big intestine. For medical diagnostics and surgery, it is required to know the position and direction of the image taken inside digestion system. This paper considers an alternative method of presurgery gastroscopy and colonoscopy monitoring procedure that allows the patient to freely move inside the medical ward. The direction-of-arrival (DOA) and inertial measurement unit (IMU) measurements are integrated to track the movement of capsule with respect to patient's body reference frame. The DOA is estimated via antenna arrays installed within a medical ward and the IMU is installed on the capsule endoscopy. The IMU sends the position information wirelessly to the antenna arrays in medical ward. Additional beacons are attached to the patient to allow body orientation and absolute position estimation due to the free movement. The nonhomogeneous nature of human body refracts the signal transmitted by the capsule, which leads to a highly nonlinear DOA function. This paper implements the unscented Kalman filter (UKF) to track the capsule by fusing the measurements made by DOA, IMU, and additional beacons attached to the patient. Simulations are conducted to investigate the capsule tracking and orientation estimation performance with respect to DOA resolution and beacons localization accuracy. Results confirm that compared with the DOA resolution, the beacons localization accuracy has a higher impact on the capsule orientation estimation performance. Furthermore, this paper investigates the impact of the number of available antenna arrays on multiplication required by UKF.

Single Beacon Indoor Localization System Based on Counter-Synchronized Compass and RSSI

Indoor localization system has been a popular research area in recent decades and many of them are based on multiple beacons localization method. However, there are some special applications to which the multiple beacons method is not an optimal solution due to its overdesign and cost of redundancy. Multiple beacons method uses at least three transducers and each transducer’s location must be known to find the location of a target object by using either Triangulation or Trilateration calculation. When the multiple beacons method is applied in an items lost and found system, the precise Cartesian coordinates of a target item can be found, but it is definitely overdesign and incurring redundant cost. It is due to the fact that the target item requires only two simple information i.e. Clock orientation and distance information; therefore, single beacon is enough for the task. In this paper, we propose a single beacon localization method to optimize the solution in the items lost and found system by utilizing clock orientation and estimated distance information. The proposed single beacon localization algorithm has been demonstrated and proven that it can be one of the optimal solutions for items lost and found system.

Improved Weighted Centroid Localization Algorithm Based On Rssi Differential Correction

abstract Node localization is one of the key technologies of wireless sensor networks (WSN). Due to the indoor environment requires a high positioning accuracy, an improved algorithm based on RSSI is put forward. In terms of RSSI ranging, the error correction coefficient received from self-correcting locator beacon nodes, and then had been applied to distance solving from unknown nodes to the beacon nodes. In the choice of weights, the algorithm uses inverse distance and replaces the method of determining the distance and the reciprocal of the weights, and also fixes the weight factor. On the complexity of the algorithm, select one of the most recent four from unknown node to beacon nodes, reducing the amount of data calculation. Simulation results show that the proposed algorithm positioning accuracy has been greatly improved.

SU‐E‐J‐32: Calypso(R) and Laser‐Based Localization Systems Comparison for Left‐Sided Breast Cancer Patients Using Deep Inspiration Breath Hold

Purpose:Our institution uses a manual laser‐based system for primary localization and verification during radiation treatment of left‐sided breast cancer patients using deep inspiration breath hold (DIBH). This primary system was compared with sternum‐placed Calypso(R) beacons (Varian Medical Systems, CA). Only intact breast patients are considered for this analysis.Methods:During computed tomography (CT) simulation, patients have BB and Calypso(R) surface beacons positioned sternally and marked for free‐breathing and DIBH CTs. During dosimetry planning, BB longitudinal displacement between free breathing and DIBH CT determines laser mark (BH mark) location. Calypso(R) beacon locations from the DIBH CT are entered at the Tracking Station. During Linac simulation and treatment, patients inhale until the cross‐hair and/or lasers coincide with the BH Mark, which can be seen using our high quality cameras (Pelco, CA). Daily Calypso(R) displacement values (difference from the DIBH‐CT‐based plan) are recorded. The displacement mean and standard deviation was calculated for each patient (77 patients, 1845 sessions). An aggregate mean and standard deviation was calculated weighted by the number of patient fractions.Some patients were shifted based on MV ports. A second data set was calculated with Calypso(R) values corrected by these shifts.Results:Mean displacement values indicate agreement within 1±3mm, with improvement for shifted data (Table).Conclusion:Both unshifted and shifted data sets show the Calypso(R) system coincides with the laser system within 1±3mm, demonstrating either localization/verification system will Resultin similar clinical outcomes. Displacement value uncertainty unilaterally reduces when shifts are taken into account.

On demand-driven movement strategy for moving beacons in sensor localization

In wireless sensor networks, estimating sensor location demands a large number of neighbor location references due to the unavoidable wireless signal attenuation problem. However, the cost of deployment increases with the increase in beacon location references. This limitation can be overcome using moving beacons exploiting the control over the number, position, and strength of beacon transmissions. In this scenario, the trade-off between localization cost and accuracy, which are directly linked up with anchor movement and transmission pattern, introduces many challenges that have recently attracted research interest. This paper aims to propose a noise-tolerant and cost-effective range-free localization technique using moving beacons that localize randomly deployed sensor nodes within a maximum localization error bound while minimizing the cost of beacon traversal and transmissions. We found that the mean localization error can be kept within 20–35% of the maximum transmission radius by selecting the movement and beacon transmission parameters according to user demand. The proposed schemes are compared with other works and also shown to be robust against positional errors of the moving beacon.

Beacon selection and calibration for the efficient localization of a mobile robot

SUMMARYThis paper proposes a localization scheme using ultrasonic beacons in an unstructured multi-block workspace. Indoor localization schemes using ultrasonic sensors have widely been studied due to their low costs and high accuracies. However, ultrasonic sensors are susceptible to environmental noise due to the propagation characteristics of ultrasonic waves. In addition, the decay of ultrasonic signals over long distances implies that ultrasonic sensors are unsuitable for use in large indoor environments. To overcome these shortcomings of ultrasonic sensors, while retaining their advantages, a multi-block approach was devised by dividing an indoor space into several blocks with multiple beacons in each block. However, it is difficult to divide an indoor space into several blocks when beacons cannot be installed in a regular manner or when some new beacons are installed. To resolve this difficulty, a dynamic algorithm is needed to divide an indoor space into multiple blocks and to select suitable beacons. Therefore, this paper proposes a real-time localization scheme to estimate the position of a mobile robot independent of beacon locations and to estimate the position of a new beacon installed at an unknown position. A beacon selection algorithm was developed to select optimal beacons according to robot position and to set up sets of beacons for mobile robot navigation. By using the new beacon searching and calibration algorithm, a mobile robot is able to navigate in an unknown space without requiring the additional setup time needed to install new beacons. The performance of the proposed localization system was verified using real experiments.

Road traffic information using a dedicated radio beacon

Traffic information is available on national and local FM radio throughout Europe. Dedicated motorway FM radio frequencies exist in some European countries. Radio traffic information limited coverage areas also exist in different countries. In this article, we present, develop and evaluate a radio beacon that instantly delivers traffic information to oncoming drivers over communication ranges several hundred meters in distance. This beacon uses a low power co-channel repeater to achieve a single isofrequency seamless communication network. The proposed local beacon effectively overrides the network-wide signal for a targeted road segment. The beacon is operated over large audience frequencies. The aim of this beacon is to deliver emergency information to drivers, using the existing unmodified car radios. No particular action is necessary for the car drivers to receive the alert information transparently. To enhance the beacon effectiveness, Radio Data System (RDS) and RDS Traffic Message Channel (RDS–TMC) services are also supported. This particular Vehicle to Vehicle communication system is intended to work as a complementary means to existing optical driver information systems. The FM radio beacon objectives are described and some initial on site measurements are performed to define the beacon technical requirements. The theoretical concept of the beacon is detailed and some associated laboratory measurements used to validate its working mode are provided. A technical description of a prototype equipment assembly is presented. Results obtained during experimentation campaigns along a motorway network are analyzed.

Design and validation of two optical beacons for guidewire localization in breast-conserving surgery

Stereotactically placed guidewires are used for indicating the location of a nonpalpable carcinoma in breast-conserving surgery. Pathologists use the end of the embedded guidewire to guide sectioning during intraoperative margin assessment, but they do not currently have a tool to indicate the location of the guidewire end for informed sectioning. We present analysis and experimental testing of two optical methods for localizing the end of an embedded fiber-optic guidewire: the first uses irradiance emitted from the fiber to indicate the location of the guidewire end, while the second system uses the fiber optic to create a photoacoustic pulse for localization. Both systems locate the end of the guidewire within ±5 mm, which ensures that the lesion of interest is bisected during sectioning. The accuracy of the irradiance-based beacon is influenced by standard margin paints, so the photoacoustic beacon proved more useful under current tissue-handling protocols.