14 research outputs found
D-SLATS: Distributed Simultaneous Localization and Time Synchronization
Through the last decade, we have witnessed a surge of Internet of Things
(IoT) devices, and with that a greater need to choreograph their actions across
both time and space. Although these two problems, namely time synchronization
and localization, share many aspects in common, they are traditionally treated
separately or combined on centralized approaches that results in an ineffcient
use of resources, or in solutions that are not scalable in terms of the number
of IoT devices. Therefore, we propose D-SLATS, a framework comprised of three
different and independent algorithms to jointly solve time synchronization and
localization problems in a distributed fashion. The First two algorithms are
based mainly on the distributed Extended Kalman Filter (EKF) whereas the third
one uses optimization techniques. No fusion center is required, and the devices
only communicate with their neighbors. The proposed methods are evaluated on
custom Ultra-Wideband communication Testbed and a quadrotor, representing a
network of both static and mobile nodes. Our algorithms achieve up to three
microseconds time synchronization accuracy and 30 cm localization error
Ultra-Wideband Angle of Arrival Estimation Based on Angle-Dependent Antenna Transfer Function
Ultra-wideband radio signals are used in communication, indoor localization and radar
systems, due to the high data rates, the high resilience to fading and the fine temporal resolution
that can be achieved with a large bandwidth. This paper introduces a new method to estimate the
angle of arrival of ultra-wideband radio signals with which existing time-of-flight based localization
and radar systems can be augmented at no additional hardware cost. The method does not require
multiple transmitter or receiver antennas, or relative motion between transmitter and receiver. Instead,
it is solely based on the angle-dependent impulse response function of ultra-wideband antennas.
Datasets on which the method is evaluated are publicly available. The method is further applied to
a localization problem and it is shown how a robot can self-localize solely based on these angle of
arrival estimates, and how they can be combined with time-of-flight measurements. Even though
existing angle of arrival techniques that use multiple antennas show better accuracy, the method
presented herein looks promising enough to be developed further and could potentially lead to
electronically and mechanically simpler angle of arrival estimation technology.ISSN:1424-822
Ultra-wideband range measurement model with Gaussian processes
This paper presents an ultra-wideband range measurement model based on Gaussian processes. An analysis of the range measurement error with off-the-shelf ultra-wideband radio modules reveals a strong correlation between the reported error and the relative pose of the two ranging modules. A Gaussian process is trained for capturing this correlation and is included in the measurement model. Its effectiveness and real-time applicability are experimentally demonstrated on a quadrocopter platform
Calibrating Away Inaccuracies in Ultra Wideband Range Measurements: A Maximum Likelihood Approach
ISSN:2169-353
A Multi-Static Radar Network with Ultra-Wideband Radio-Equipped Devices
A growing number of devices, from car key fobs to mobile phones to WiFi-routers, are equipped with ultra-wideband radios. In the network formed by these devices, communicating modules often estimate the channel impulse response to employ a matched filter to decode transmitted data or to accurately time stamp incoming messages when estimating the time-of-flight for localization. This paper investigates how such measurements of the channel impulse response can be utilized to augment existing ultra-wideband communication and localization networks to a multi-static radar network. The approach is experimentally evaluated using off-the-shelf hardware and simple, distributed filtering, and shows that a tag-free human walking in the space equipped with ultra-wideband modules can be tracked in real time. This opens the door for various location-based smart home applications, ranging from smart audio and light systems to elderly monitoring and security systems.ISSN:1424-822
State Estimate Recovery for Autonomous Quadcopters
A method for recovery from the complete loss of the state estimate is presented for autonomous quadcopters. Given an aerodynamic force model, the only measurements used to reinitialize the state estimate by means of a bank of extended Kalman filters are the angular rate and linear acceleration measurements of an IMU. The method is integrated within a complete recovery logic on a quadcopter platform and experimentally evaluated
Real-time hybrid dike breach model: simulating reservoirs of arbitrary shape and volume in laboratory tests
ISSN:0022-1686ISSN:1814-207