Emidio DiGiampaolo

A Passive UHF-RFID System for the Localization of an Indoor Autonomous Vehicle

A global localization system combining odometry data with radio frequency identification (RFID) readings is proposed. RFID tags are placed at the ceiling of the environment and can be detected by a mobile robot unit traveling below them. The detection of the tags is the only information used in the proposed approach (no distance or bearing to the tag is considered available), but differently from similar localization setups reported in the literature, only a small number (about one each square meter or less) of tags are used. This is possible using a suitable tags antenna in ultrahigh frequency band, expressly designed to obtain regular and stable RFID detection regions, which allows us to consider an efficient Kalman filtering approach to fuse RFID readings with the vehicle odometry data. A satisfactory performance is achieved, with an average position error of about 0.1 m. The hardware/software localization setup described in this paper is cheap and easy to use and may provide a satisfactory approach in several industrial and domestic scenarios.

Mobile Robot Localization Using the Phase of Passive UHF RFID Signals

This paper presents a global localization system for an indoor autonomous vehicle equipped with odometry sensors and a radio-frequency identification (RFID) reader to interrogate tags located on the ceiling of the environment. The RFID reader can measure the phase of the signals coming from responding tags. This phase has non-univocal dependence on the distance robot tag, but in the considered frequency, it is really sensitive to a change in the position of the robot. For this reason, a multihypothesis Kalman filtering approach provides a really satisfactory performance even in the case that a very small density of tags is used: In the experimental tests, an average position estimation error of about 4 cm is achieved using only two tags for an area of about 5 m2.

Wireless Crack Monitoring by Stationary Phase Measurements from Coupled RFID Tags

The possibility to wirelessly monitor the state and the evolution of cracks is of increasing interest in emerging structural health monitoring systems. A simple and effective measurement method considers the placement of two passive radio frequency identification (RFID) antennas on top of the crack, so that the cracks evolution will produce a change of the inter-antenna coupling and in turn of the phase of the backscattered field. An ad-hoc design technique, based onto the coupled-modes physics, permits to maximize the sensors sensitivity avoiding, or at least mitigating, the read range reduction during the evolution of the displacement that is instead typical of amplitude-oriented RFID displacement sensors. The proposed idea is demonstrated by numerical and experimental examples showing the possibility of sub-millimeter resolution with low-cost devices.

Wireless Passive RFID Crack Width Sensor for Structural Health Monitoring

All mechanical structures are subjected to deformation and cracks, due to fatigue, stress, and/or environmental factors. It is, therefore, of uttermost importance to monitor the mechanical condition of critical structures, in order to prevent catastrophic failures, but also to minimize maintenance costs, i.e., avoid unnecessary inspections. A number of technologies and systems can be used for this purpose: among them, the ones proposing the use of wireless passive crackmeters have a strong impact potential, in terms of simplicity of installation and measurement and low cost. This paper, hence, shows a crack width wireless radio-frequency identification sensor, developed for applications on various materials (such as concrete and metal) and able to detect submillimeter deformations occurring on the object, on which it is placed. A design method based on high-sensitivity phase detection is shown.

Constrained Pole-Zero Synthesis of Phase-Oriented RFID Sensor Antennas

Passive sensing by means of radiofrequency identification has been extensively explored for various applications, such as gas detection, temperature change, and deformation. The sensing indicator is generally based on the amplitude and phase of the backscattered field. However, a degradation of the communication performance must be usually accepted for achieving the sensing capability. This work introduces a design method suitable for phase-based RFID sensors that permits to shape the phase response while preserving the impedance matching between the antenna and the microchip. The RFID sensor is modeled as a two-ports scatterer comprising a lumped sensor at one of the ports and an RFID chip at the other port. A pole-zero representation of the electromagnetic interaction between the reader and the RFID sensor allows to introduce a constrained design of the antenna with a full control on the sensor dynamic range and on the communication performance. The proposed method is numerically and experimentally validated by means of a pair of strongly coupled dipoles connected to a voltage-controlled varactor emulating a dynamic sensor response.

An RFID-Enabled Wireless Strain Gauge Sensor for Static and Dynamic Structural Monitoring

Strain gauge measurements are widely used in structural health monitoring and damage detection of existing infrastructures as well as in laboratory prototyping tests of new structures and materials. Wireless sensing of strain gauge is desirable in many practical applications because of the difficulty to access at the measurement point or to handle wired sensors. In this paper, we show a semi-passive wireless strain gauge sensor, which allows a high level of measurement accuracy comparable with that of wired strain sensors. It overcomes the limits and drawbacks of devices based on wireless sensor networks and those based on similar RFID-based sensors. The ability to perform measurements over long distances and to handle fast time-varying phenomena (e.g., vibration) makes the proposed device practical in realistic scenarios.

Investigation of suitable parameters for setup-independent RFID sensing

RFID systems are growing in use also for sensing purposes. In the last years, there has been quite a lot of effort in identifying RFID parameters most suited to sensing and at the same time wirelessly recordable: there are however still some open issues to solve. The use of wirelessly recordable parameters being independent from the measurement setup is surely one of the most interesting open questions and promises, if solved, significant improvements to the state of the art of RFID sensing. This work shows hence two such parameters and analyzes their performance in terms of setup independence.