A Framework for NLOS Ultra-Wideband Ranging in Collaborative Mobile Robot Systems

Ultra-wideband (UWB) localization is one of the most promising indoor localization methods. Yet, non-line-of- sight (NLOS) positioning scenarios remain a challenge and can potentially cause significant localization errors. In this work, we leverage the collaborative paradigm of a multi-robot system by sharing relative positioning information, and thus alleviating error susceptibility in NLOS ranging scenarios. In particular, we detail a decentralized particle filter based localization algorithm which combines an UWB range model with a robot detection model. Finally, we test both collaborative and non-collaborative versions of our algorithm in simulation, in mixed LOS/NLOS scenarios. Results show superior performance for the collabora- tive system when compared to non-collaborative systems utilizing only UWB rangin

Accommodation of NLOS for Ultra-Wideband TDOA Localization in Single- and Multi-Robot Systems

Ultra-wideband (UWB) localization is one of the most promising indoor localization methods. Yet, non-line-ofsight (NLOS) positioning scenarios remain a challenge and can potentially cause significant localization errors. In this work, we leverage the utility of a group of mobile robots to test and validate our approach systematically in a real world setup. We use a particle filter based localization algorithm, which is wellsuited for accommodating arbitrary observation models, with the ultimate purpose of integrating various sensory information within a single framework. In particular, we propose a novel, probabilistic UWB TDOA error model which explicitly takes into account NLOS, and introduce it into our localization framework in combination with a standard motion model based on deadreckoning information. We subsequently extend our single-robot localization framework to a multi-robot, collaborative system by enabling the sharing of relative, inter-robot observations. Our experimental results show how the novel TDOA error model is able to improve localization performance when knowledge of the LOS/NLOS path condition is available. These results are complemented by additional experiments which show how a collaborative team of robots is able to significantly improve localization performance when poor knowledge of LOS/NLOS path condition is available

Improving pedestrian dynamics modelling using fuzzy logic

The complementary nature of MEMS based pedestrian dead-reckoning (PDR) navigation and GNSS (Global Navigation Satellite System) has long been recognised. The advantages are quite clear for those applications requiring indoor positioning and that, for one reason or another, cannot rely with the lack of availability of GNSS indoors. One such example of application is firemen coordination during emergency interventions

Indoor Navigation of Emergency Agents

Existing indoor navigation solutions usually rely on pre-installed sensor networks, whereas emergency agents are interested in fully auto-deployable systems. In this paper, an almost self-deployable solution based on Radio-frequency identification tags and inertial Micro Electro Mechanical Sensors is presented. The benefits of the solution are evaluated and compared with the pure inertial positioning system

Assessment of the Integration Strategy between GPS and Body-Worn MEMS Sensors with Application to Sports

This paper describes experiments that were performed involving a professional downhill skier equipped with a low-cost L1 GPS receiver and a MEMS-IMU composed of 3 single axis gyroscopes, accelerometers and magnetometers. In addition, the skier carried an L1/L2 GPS receiver and a tactical-grade IMU (LN200). The experiments aimed to assess the navigation performance of different GPS/MEMS-IMU integration strategies compared to high-quality GPS/INS integration. After presenting an overview of currently applied integration methods, the unscented Kalman filter approach in loosely coupled mode. The relevance of the simple MEMS-IMU sensor error model was verified by comparing the filter output to the reference data

Implementation and Performance of a GPS/INS Tightly Coupled Assisted PLL Architecture Using MEMS Inertial Sensors

The use of global navigation satellite system receivers for navigation still presents many challenges in urban canyon and indoor environments, where satellite availability is typically reduced and received signals are attenuated. To improve the navigation performance in such environments, several enhancement methods can be implemented. For instance, external aid provided through coupling with other sensors has proven to contribute substantially to enhancing navigation performance and robustness. Within this context, coupling a very simple GPS receiver with an Inertial Navigation System (INS) based on low-cost micro-electro-mechanical systems (MEMS) inertial sensors is considered in this paper. In particular, we propose a GPS/INS Tightly Coupled Assisted PLL (TCAPLL) architecture, and present most of the associated challenges that need to be addressed when dealing with very-low-performance MEMS inertial sensors. In addition, we propose a data monitoring system in charge of checking the quality of the measurement flow in the architecture. The implementation of the TCAPLL is discussed in detail, and its performance under different scenarios is assessed. Finally, the architecture is evaluated through a test campaign using a vehicle that is driven in urban environments, with the purpose of highlighting the pros and cons of combining MEMS inertial sensors with GPS over GPS alone

Sensor-Augmented EGNOS/Galileo Receiver for Handheld Applications in Urban and Indoor Environments - SARHA

In pedestrian user environments, like dense urban canyons or indoors, the GNSS positioning performance regarding accuracy and availability reaches well-known technological limits. These limitations can be overcome by adding additional sources of information to the system. The main objective of the project ‘SARHA - Sensor-Augmented EGNOS/Galileo Receiver for Handheld Applications in Urban and Indoor Environments’ is the combination of a modern satellite navigation receiver with augmentation and autonomous sensors. Additionally, the hybrid navigation system will be enhanced by a transponder receiver, which communicates with transmitters installed inside buildings, to provide absolute position updates. The transponder will allow the SARHA system to significantly increase reliability and accuracy of the positioning solutions indoors. The hybrid navigation software is split up into two parts. The first one will be implemented directly on the GPS receiver, whereas the second part will run on a microcontroller. In this way a small, low-performance microcontroller can be used, what represents the first step to reduce dimension, weight and energy consumption of the mobile system. The project aims at meeting the requirements of fire fighters, rescue services, police, special task forces, solitary, and lone workers for handheld applications acting in environments with unfavourable satellite signal conditions, using hybrid navigation system architecture. Based on the Galileo signal definitions, analyses are set up to explore the signal characteristics in comparison to the GPS signals. Improvements due to Galileo signal availability in urban and indoor environments are assessed and will later ensure seamless integration of enhanced technologies into continuous developments

SARHA – Development of a Sensor-Augmented GPS/EGNOS/Galileo Receiver for Urban and Indoor Environments

The main objective of the project ‘SARHA - Sensor-Augmented EGNOS/Galileo Receiver for Handheld Applications in Urban and Indoor Environments’ is the development of a modern satellite navigation receiver with autonomous sensor augmentation. Additionally, the hybrid navigation system will be enhanced by a transponder capable of receiving absolute position updates from transmitters installed inside buildings. The transponder will allow the SARHA system to significantly increase reliability and accuracy of the positioning solutions indoors. The hybrid navigation software is split up into two parts. The first one will be implemented directly on the GPS receiver, whereas the second part will run on a microcontroller. Thus, a small, low-performance microcontroller can be used, representing the first step towards the reduction of size, weight and power consumption of the mobile system. This paper provides an overview on personal mobility and typical applications related to the system, describes the system architecture and the hybrid navigation software in detail. Furthermore, emphasis is laid on a comparison of different step detection algorithms, showing their advantages and disadvantages. Based on the Galileo signal definition, additional analysis set up to explore the signal characteristics in comparison to the GPS signals, are provided. Improvements due to the Galileo signal availability in urban and indoor environments are assessed and will later ensure seamless integration of enhanced technologies into the continuous developments

Location System and Corresponding Calibration Method

The present invention relates to a location system, for locating at least one object within a predefined cell, comprising at least first and second receivers (A, B, C, D), first and second transmitters respectively, including first and second internal clocks (rxA, rxB, rxC, rxD), the receivers, the transmitters respectively, having known locations, a transmitter, a receiver respectively, worn by the object and designed to communicate by means of signal exchanges with the receivers, the transmitters respectively, electronic circuits designed to compute a position related information of the object based on the signal exchanges, at least two reference transmitters (1, 2, 3), two reference receivers respectively, arranged to carry out a calibration operation of the first and second internal clocks, the system being characterized by the fact that it comprises a support adapted to link the two reference transmitters (1, 2), two reference receivers respectively, to each other, the support being configured such that it may be set at least in a first calibration configuration in which the two reference transmitters (1, 2), two reference receivers respectively, have a relative distance (dtx1/tx2) with respect to each other which is, a priori, known for the purpose of carrying out the calibration operation