Placement Of Beacons Research Articles

OPTILOD: Optimal Beacon Placement for High-Accuracy Indoor Localization of Drones.

For many applications, drones are required to operate entirely or partially autonomously. In order to fly completely or partially on their own, drones need to access location services for navigation commands. While using the Global Positioning System (GPS) is an obvious choice, GPS is not always available, can be spoofed or jammed, and is highly error-prone for indoor and underground environments. The ranging method using beacons is one of the most popular methods for localization, especially for indoor environments. In general, the localization error in this class is due to two factors: the ranging error, and the error induced by the relative geometry between the beacons and the target object to be localized. This paper proposes OPTILOD (Optimal Beacon Placement for High-Accuracy Indoor Localization of Drones), an optimization algorithm for the optimal placement of beacons deployed in three-dimensional indoor environments. OPTILOD leverages advances in evolutionary algorithms to compute the minimum number of beacons and their optimal placement, thereby minimizing the localization error. These problems belong to the Mixed Integer Programming (MIP) class and are both considered NP-hard. Despite this, OPTILOD can provide multiple optimal beacon configurations that minimize the localization error and the number of deployed beacons concurrently and efficiently.

The role of crosswalk-related features on drivers' spatial yielding compliance at signalized midblock crosswalks

The drivers' yielding distance to pedestrians at midblock crosswalks affects pedestrians' perceived safety. This distance can be influenced by either crosswalk-related or non-crosswalk. In most cases, crosswalk-related features are readily available or easy to collect compared to non-crosswalk features. However, the extent to which crosswalk-related features affect the spatial yielding compliance is not clear. This study evaluated the role of combined crosswalk-related features on drivers' spatial yielding compliance at signalized midblock crosswalks. The study used observational survey data collected from fifteen flash-based signalized midblock crosswalks located in Las Vegas, Nevada. Three logistic regression models, with crosswalk-related features only, non-crosswalk features only, and combined features, were developed and compared. It was revealed that the performance difference between the model with crosswalk-related features only and combined features was insignificant. This study found that the presence of state's law signs, “PED XING” signs, and placement of rectangular rapid flashing beacons (RRFBs) on the advanced pedestrians crossing signs (APCSs), are significant factors for high spatial yielding compliance. On the contrary, the yield line's presence at a distance greater than 40 ft from the crosswalk, presence of one stage crossing, and high Annual Average Daily Traffic (AADT) negatively affects the spatial yielding compliance. Moreover, the findings suggest that researchers should be careful about excluding the non-crosswalk features from the analysis. To improve spatial yielding compliance, several recommendations that the city planners and engineers can adopt are provided. • This study evaluated drivers' yielding compliance at the midblock crosswalk. • The influences of various features on spatial yielding compliance were evaluated. • The state's law and “PED XING” signs increases spatial yielding compliance. • A longer distance from yield lines to marked strips decreases spatial yielding compliance.

Deployment Method and Optimal Placement of Surface Beacon Navigation System for Co-located Lunar Landings

Lunar Space exploration is currently accelerating, and manned and unmanned missions to the Moon are planned by several space agencies and private companies in the coming 5–10 years. The construction of the Lunar Orbital Platform Gateway (LOP-G) and plans to establish a more permanent human presence on the Lunar surface will increase the landing frequency and require the capability to safely soft-land successive missions in near proximity to each other. The lunar South Pole is one of the preferred locations for surface exploration due to the discovery of volatiles in the permanently shadowed craters at the poles. However, landing on the lunar South Pole of the Moon is challenging due to the illumination and loss of Earth line-of-sight conditions combined with complex topography. The increased interest in co-located lunar landings concurrent with construction of lunar infrastructure and a challenging landing area warrants new approaches in navigation technology.In this paper we present a concept for a system of radio beacons installed around the Shackleton crater rim “SR1” landing site on the lunar South Pole. We present considerations for optimal placement of the radio beacons based on the specific landing site topography and quantify our finding with dilution of precision (DOP) calculations. We present a novel method for deploying the radio beacons as penetrators with embedded thermoelectric generators (TEGs) for autonomous power generation. We present findings on beacon survivability, penetration depth, spin-stabilization of the penetrators and maximal theoretical power generation.

Power Beacon Placement for Maximizing Guaranteed Coverage in Bistatic Backscatter Networks

The bistatic backscatter architecture, with its extended range, enables flexible deployment opportunities for backscatter devices. In this paper, we study the placement of power beacons (PBs) in bistatic backscatter networks to maximize the guaranteed coverage distance (GCD), defined as the distance from the reader within which backscatter devices are able to satisfy a given quality-of-service constraint. This work departs from conventional energy source placement problems by considering the performance of the additional backscatter link on top of the energy transfer link. We adopt and optimize a symmetric PB placement scheme to maximize the GCD. The optimal PB placement under this scheme is obtained using either analytically tractable expressions or an efficient algorithm. Numerical results provide useful insights into the impacts of various system parameters on the PB placement and the resulting GCD, plus the advantages of the adopted symmetric placement scheme over other benchmark schemes.

Optimal Beacon Placement for Self-Localization Using Three Beacon Bearings

Autonomous vehicles need to localize themselves within the environment in order to effectively perform most tasks. In situations where a Global Navigation Satellite System such as the Global Positioning System cannot be used for localization, other methods are required. One self-localization method is to use signals transmitted by beacons at known locations to determine the relative distance and bearing of the vehicle from the beacons. Estimation performance is influenced by the beacon–vehicle geometry and the investigation into the optimal placement of beacons is of interest to maximize the estimation performance. In this article, a new solution to the optimal beacon placement problem for self-localization of a vehicle on a two-dimensional plane using angle-of-arrival measurements is proposed. The inclusion of heading angle in the estimation problem differentiates this work from angle-of-arrival target localization, making the optimization problem more difficult to solve. First, an expression of the determinant of the Fisher information matrix for an arbitrary number of beacons is provided. Then, a procedure for analytically determining the optimal angular separations for the case of three beacons is presented. The use of three beacons is motivated by practical considerations. Numerical simulations are used to demonstrate the optimality of the proposed method.

Optimizing AP and Beacon Placement in WiFi and BLE hybrid localization

Nowadays, wireless communication techniques, such as WiFi, Bluetooth low energy (BLE), etc., have been pervasive in our daily lives, and not only provide convenient data transmission services, but also enable popular indoor positioning and navigation services. The placement of wireless infrastructures like WiFi access points (APs) and BLE beacons have significant influences on the performance of localization. More importantly, since APs and beacons are probably used for both network access and localization, it is necessary to take into account both coverage and localization when deploying APs and beacons. In addition, there still exist other critical challenges, including optimizing AP and beacon placement in WiFi and BLE hybrid localization and optimizing the placement of extra APs and/or beacons in an existing wireless network, which are essentially NP-complete. This paper tackles these problems of optimizing AP and beacon placement by proposing a heuristic differential evolution algorithm based on the widely used Cramer-Rao lower bound (CRLB). To be specific, the CRLB is leveraged as a metric for localization and meanwhile a coverage degree criterion is defined as a metric for coverage, both of which are incorporated into the evaluation function of the differential evolution algorithm. Furthermore, instead of using the ideal log distance path loss (LDPL) model, the more practical Motley-Keenan model is adopted to reflect the influences of obstacles that are widespread in indoor environments. On these grounds, a software is designed and implemented based on Geotools to optimize AP and beacon placement in an interactive GUI manner. Finally, extensive simulations and field experiments are conducted, and a thorough comparison confirms the efficiency and effectiveness of the proposed algorithm.

Comparison of Above-Sign and Below-Sign Placement of Rectangular Rapid-Flashing Beacons

Several methods have been used to emphasize the presence of a pedestrian crossing, including supplementing signing with beacons. A device that has received national attention is the rectangular rapid-flashing beacon (RRFB). A question being asked is whether the position of the beacons above or below the pedestrian crossing sign influences the effectiveness of the treatment. A closed-course study found that at night RRFBs located above the crossing sign offered advantages compared with LEDs located within or below the sign. To determine if the position of the beacons affected driver yielding, RRFBs were installed above and below the pedestrian crossing sign at 13 sites in four locales. A staged pedestrian protocol was used to collect driver yielding to ensure a consistent presentation of approaching pedestrians. Preliminary findings showed only minor, if any, differences between the above and below positions (average daytime yielding for staged pedestrians was 64% for above and 61% for below), and the statistical test showed no significant difference. The open-road study found that the position of the RRFB did not affect a driver’s decision to yield. With apparent benefits identified from the closed-course study—i.e., lower discomfort and improved ability to detect the pedestrian as measured by identifying the direction a cutout photo of a pedestrian is traveling—and the lack of difference in driver yielding as a result of position, locating the beacons above the warning sign could improve the overall effectiveness of this treatment. As a result of these findings, FHWA plans to issue an official interpretation permitting placement of the beacons above the crossing warning sign.

Indoor radio location algorithm using empirical propagation models and probability distribution heuristics

Research is conducted at the Budapest University of Technology in the field of indoor positioning using radio waves, with practical application issues in focus. Our goal is to enhance and combine existing algorithms and create an implementation that is efficient enough to enable real-time operation in 3D space in multi-level office environments while retaining the accuracy of more complex systems. The proposed solution is based on proven empirical propagation models (the Motley-Keenan Model and the New Empirical Model of Cheung, Sau and Murch), with the ability to augment and refine with surveyed radio fingerprint data. The propagation model described in this paper can be used to generate estimated signal strength patterns for locations that were left out of the survey; and the values coming from the two different sources can be further handled in a common way. An algorithm is proposed to calculate a probability distribution over the floor plan using these expected values and the positioning-time measurements. The results from this location algorithm are combined with other probability distributions, generated by heuristics such as the distribution of walls, previous walking directions and typical indoor movement patterns, as well as data from G-sensors and digital compasses built into modern handheld devices. Other real-world issues are investigated like reaction to changes in the placement of radio beacons, and the comparability of various devices with different signal characteristics. The proposed algorithm can achieve an average positioning error of 3 metres in a common office environment using fingerprinting data, and errors are only about 50%greater when relying solely on simulated signal strength values.

Optimal sensor positioning for large scale metrology applications

As it strongly affects the system performance in measuring 3D point coordinates, beacon positioning represents a challenging issue in large scale metrology applications based on wireless sensor networks. This paper presents a software-assisted procedure for efficient placement of ultrasonic beacons in a wireless distributed network-based system for medium–large sized object measurements. A regular grid-based strategy and a genetic algorithm-based approach to the deployment problem are presented. The resulting network configurations are compared in terms of overall costs, sensor availability and measurement precision. The genetic algorithm outperforms the regular deployment solution, optimizing the objective functions and providing additional capabilities to represent a realistic working environment. The novelty here is the approach to the “pre-processing” phase of a sensor network deployment, involving working environment constraints, system functional characteristics, measurand geometry, and measurement task definition in the three-dimensional network design.

Placement of network services in a sensor network

An important challenge in designing a wireless sensor network is to maximise the network's lifetime. In a hierarchical cluster-based network, a key design issue is the placement of cluster heads (data loggers) such that the total power consumed by the overall network is minimised. Another key design goal is the localisation of sensors. In this study, we consider the placement of beacons and data loggers in the Cosumnes River Preserve. We consider a hybrid network in which the wireless sensors are deployed randomly into an irregular terrain while the data loggers and beacons are placed in a planned manner to satisfy the following three objectives: provide complete area coverage; load balance each cluster; minimise the total power consumption for collecting the data. We formulated an optimisation problem to determine the location of data loggers and beacons which is solved using an Integer Linear Program (ILP).

Self-configuring localization systems

Embedded networked sensors promise to revolutionize the way we interact with our physical environment and require scalable, ad hoc deployable and energy-efficient node localization/positioning.This paper describes the motivation, design, implementation, and experimental evaluation (on sharply resource-constrained devices) of a self-configuring localization system using radio beacons. We identify beacon density as an important parameter in determining localization quality, which saturates at a transition density. We develop algorithms to improve localization quality by (i) automating placement of new beacons at low densities (HEAP) and (ii) rotating functionality among redundant beacons while increasing system lifetime at high densities (STROBE).