In recent years, indoor positioning has emerged as a critical function in many end-user applications; including military, civilian, disaster relief and peacekeeping missions. In comparison with outdoor environments, sensing location information in indoor environments requires a higher precision and is a more challenging task in part because various objects reflect and disperse signals. Ultra WideBand (UWB) is an emerging technology in the field of indoor positioning that has shown better performance compared to others. In order to set the stage for this work, we provide a survey of the state-of-the-art technologies in indoor positioning, followed by a detailed comparative analysis of UWB positioning technologies. We also provide an analysis of strengths, weaknesses, opportunities, and threats (SWOT) to analyze the present state of UWB positioning technologies. While SWOT is not a quantitative approach, it helps in assessing the real status and in revealing the potential of UWB positioning to effectively address the indoor positioning problem. Unlike previous studies, this paper presents new taxonomies, reviews some major recent advances, and argues for further exploration by the research community of this challenging problem space.

https://www.mdpi.com/1424-8220/16/5/707/pdf

Ultra Wideband Indoor Positioning Technologies: Analysis and Recent Advances.

The availability of location information has become a key factor in today's communications systems allowing location based services. In outdoor scenarios, the mobile terminal position is obtained with high accuracy thanks to the global positioning system (GPS) or to the standalone cellular systems. However, the main problem of GPS and cellular systems resides in the indoor environment and in scenarios with deep shadowing effects where the satellite or cellular signals are broken. In this paper, we survey different technologies and methodologies for indoor and outdoor localization with an emphasis on indoor methodologies and concepts. Additionally, we discuss in this review different localization-based applications, where the location information is critical to estimate. Finally, a comprehensive discussion of the challenges in terms of accuracy, cost, complexity, security, scalability, etc. is given. The aim of this survey is to provide a comprehensive overview of existing efforts as well as auspicious and anticipated dimensions for future work in indoor localization techniques and applications.

Recent Advances in Indoor Localization: A Survey on Theoretical Approaches and Applications

.............................................................................................................................................................. 6 1 Introduction ............................................................................................................................................. 7 1.1 Motivation .......................................................................................................................................................... 7 1.2 Previous Surveys ............................................................................................................................................. 8 1.3 Overview of Technologies ........................................................................................................................... 9 1.4 Indoor Positioning Applications ............................................................................................................ 11 1.5 Structure of this Work ............................................................................................................................... 14 2 User Requirements ............................................................................................................................. 15 2.1 Requirements Parameters Overview .................................................................................................. 15 2.2 Positioning Requirements Parameters Definition ......................................................................... 17 2.3 Man Machine Interface Requirements ................................................................................................ 19 2.4 Security and Privacy Requirements ..................................................................................................... 20 2.5 Costs .................................................................................................................................................................. 20 2.6 Generic Derivation of User Requirements......................................................................................... 20 2.7 Requirements for Selected Indoor Applications ............................................................................. 21 3 Definition of Terms ............................................................................................................................. 25 3.1 Disambiguation of Terms for Positioning .......................................................................................... 25 3.2 Definition of Technical Terms ................................................................................................................ 27 3.3 The Basic Measuring Principles ............................................................................................................. 29 3.4 Positioning Methods ................................................................................................................................... 31 4 Cameras .................................................................................................................................................. 34 4.1 Reference from 3D Building Models .................................................................................................... 35 4.2 Reference from Images .............................................................................................................................. 36 4.3 Reference from Deployed Coded Targets .......................................................................................... 37 4.4 Reference from Projected Targets ........................................................................................................ 38 4.5 Systems without Reference ..................................................................................................................... 39 4.6 Reference from Other Sensors ............................................................................................................... 40 4.7 Summary on Camera Based Indoor Positioning Systems ........................................................... 40 5 Infrared ................................................................................................................................................... 42 5.1 Active Beacons .............................................................................................................................................. 42 5.2 Imaging of Natural Infrared Radiation ............................................................................................... 43 5.3 Imaging of Artificial Infrared Light ....................................................................................................... 43 5.4 Summary on Infrared Indoor Positioning Systems ....................................................................... 44

Indoor Positioning Technologies

The Global Positioning System (GPS) can be readily used for outdoor localization, but GPS signals are degraded in indoor environments. How to develop a robust and accurate indoor localization system is an emergent task. In this paper, we propose a smartphone inertial sensor-based indoor localization and tracking system with occasional iBeacon corrections. Some important issues in a smartphone-based pedestrian dead reckoning (PDR) approach, i.e., step detection, walking direction estimation, and initial point estimation, are studied. One problem of the PDR approach is the drift with walking distance. We apply a recent technology, iBeacon, to occasionally calibrate the drift of the PDR approach. By analyzing iBeacon measurements, we define an efficient calibration range where an extended Kalman filter is utilized. The proposed localization and tracking system can be implemented in resource-limited smartphones. To evaluate the performance of the proposed approach, real experiments under two different environments have been conducted. The experimental results demonstrated the effectiveness of the proposed approach. We also tested the localization accuracy with respect to the number of iBeacons.

Smartphone Inertial Sensor-Based Indoor Localization and Tracking With iBeacon Corrections

In this paper, we concern ourselves with the development of a localization system that permits multiple robots to localize themselves simultaneously within a given area, which has been outfitted with a network of stationary radio modules. We derive a clock synchronization scheme for the radio modules, show how each module is able to compute its position within the network, and finally demonstrate how multiple robots are able to operate simultaneously within the space by using time-difference-of-arrival measurements to localize themselves. Since robots are passive receivers in this system and are able to compute their position based only on received and local information, multiple robots can operate simultaneously and without the need for central coordination or centralized localization infrastructure. All results presented in this paper are supported by experimental results, and the functionality of the system is demonstrated by multiple micro-quadrocopters localizing and flying simultaneously within a space.

Self-Calibrating Ultra-Wideband Network Supporting Multi-Robot Localization

Typical indoor environments contain multiple walls and obstacles consisting of different materials. As a result, current narrowband radio frequency (RF) indoor navigation systems cannot satisfy the challenging demands for most indoor applications. The RF ultra wideband (UWB) system is a promising technology for indoor localisation owing to its high bandwidth that permits mitigation of the multipath identification problem. This work proposes a novel UWB navigation system that permits accurate mobile robot (MR) navigation in indoor environments. The navigation system is composed of two sub-systems: the localisation system and the MR control system. The main contributions of this work are focused on estimation algorithm for localisation, digital implementation of transmitter and receiver and integration of both sub-systems that enable autonomous robot navigation. For sub-systems performance evaluation, statics and dynamics experiments were carried out which demonstrated that the proposed system reached an accuracy that outperforms traditional sensors technologies used in robot navigation, such as odometer and sonar.

Ultra wideband indoor navigation system

A self-localized Ultra-Wide-Band (UWB) system that is suitable to navigate mobile robots in indoor environments is introduced. In impulse-based UWB systems, positional accuracy is inversely proportional to the signal bandwidth. In the work, a number of anchor nodes are located at fixed positions in an indoor environment transmitting synchronized 2ns pulses with Differential Binary Phase Shift Keying (DBPSK) modulation. An UWB receiver mounted on a mobile robot utilizes Time Difference of Arrival (TDOA) between pairs of synchronized transmitting anchor nodes for localization. Self-localization implies that position estimation algorithms run locally on the mobile robot. A prototype non-coherent UWB system using off-the-shelf components is implemented where signal acquisition runs on a Field Programmable Gate Array (FPGA). Measurement results indicate sub-20cm positional accuracy with Line Of Sight (LOS) and Non-Line of Sight (NLOS) conditions relative to fixed anchor nodes in a typical indoor environment.

Experimental demonstration of self-localized Ultra Wideband indoor mobile robot navigation system

Nowadays the need for dealing with ultra-high speed Analog to Digital Converter (ADC) is becoming more and more common, from Telecommunications to Precise Instrumentation, every application is increasing the analog to digital interface data rate. The ultra-high sampling rate of the ADCs demands the use of advanced acquisition techniques as well as the latest technology available. The utilization of dedicated Application Specific Integrated Circuit (ASIC) is an expensive solution to deal with the very high throughput from the ADC and its lack of flexibility is a huge drawback. On the other hand, the technology, the architecture and the state-of-the art of the current Field Programmable Gate Arrays (FPGAs) make them especially suitable to act as interface between an ultra-high speed ADC and a data processing unit. Another extra advantage is the reconfigurability of the FPGAs, they can be quickly adapted to different ADCs or different data processing units. The purpose of this paper is to present a practical approach to interface an ultra-high speed 8-bit ADC, MAX104, from Maxim Integrated Circuit, which performs digitalization of the input signal with a sampling rate of 1Gsps and a commercial and popular FPGA, the Virtex2 Pro, from Xilinx Corporation. Once the ADC digital data have been acquired, then they can be processed by either the dedicated FPGA Digital Signal Processing (DSP) blocks, or the FPGA embedded processors or just send the data out to a PC for later processing. Hence, the proposed method of implementation can be used as front-end of a wide range of applications.

FPGA implementation of an ultra-high speed ADC interface

This work proposes an improved Real Time Localization System using UWB technology, for people and asset tracking in a closed environment, particularly in underground mines. The UWB technology has demonstrated a very good performance with a localization error margin below 41 centimeters. The main objective of this work was to develop an affordable, easy to use, and scalable localization system to detect people in underground mines that allows fast location and rescue in case of disaster. It can also improve the mine productivity under normal conditions. Different tests were carried out in mines and urban buildings to validate the design and evaluate the error margin. The test in an underground mine was done at “Casposo Mining”, which is located in the town of Calingasta, San Juan province, Argentina. Finally, an autonomy of 25 hours of continuous used was achieved using a 2000mAh battery.

Human Real Time Localization System in Underground Mines using UWB

In impulse-based UWB systems, positional accuracy is inversely proportional to the signal bandwidth. In this work, a number of anchor nodes are located at fixed positions in an indoor environment transmitting synchronized 2.5ns pulses with Differential Binary Phase Shift Keying (DBPSK) modulation. An UWB receiver mounted on a mobile robot utilizes Time Difference of Arrival (TDOA) between pairs of synchronized transmitting anchor nodes for localization. Self-localization implies that position estimation algorithms run locally on the mobile robot. A prototype non-coherent UWB receiver using off-the-shelf components is implemented where signal acquisition runs on a Field Programmable Gate Array (FPGA). Measurement results indicate sub-20cm positional accuracy with Line Of Sight (LOS) and Non-Line of Sight (NLOS) conditions relative to fixed anchor nodes in a typical indoor environment.

Cristian Sisterna

Papers

Ultra wideband indoor navigation system

Experimental demonstration of self-localized Ultra Wideband indoor mobile robot navigation system

FPGA implementation of an ultra-high speed ADC interface

Human Real Time Localization System in Underground Mines using UWB

Ultra wideband digital receiver implemented on FPGA for mobile robot indoor self-localization