Health Articles

 

Microsoft word - autonomous_self-sufficient_positioning_system.doc

AUTONOMOUS SELF-SUFFICIENT POSITIONING SYSTEM
WITH TOLL DETECTION
Tiago Lindeza, Delfim Pinto, Ricardo Prata, André Costa R&D department, Dailywork Lda, Lisbon, Portugal {tiago.lindeza, delfim.pinto, ricardo.prata, andre.costa}@dailywork.pt Energy harvesting, low power localization, transportation, GPS, DSRC This document presents an innovative solution to extend the lifetime of autonomous positioning systems used in the transportation sector. The integration of a solar and mechanical energy harvesters along with the appropriate conditioning circuit, into the main location system are the key to reduce the dependence of batteries. Also, a toll detection circuit was added to provide information about crossing toll stations. 1 INTRODUCTION
2 STATE OF THE ART
The accentuated globalization of trade in the last Energy Harvesting is a technique [3] that captures decades by land, sea and air, led the companies the energy present in the environment and converts needs to depend on transportation networks and it into electrical energy. The harvesting is carried by systems for an effective fleet management, in order a transducer (eg: a solar panel, a Peltier cell, a to optimize resources. The success of these systems propeller, a piezoelectric material, etc) which is directly related to the ability to identify produces a voltage or electric current. Then, it is periodically and accurately the location of vehicles necessary to regulate this voltage/current to allow and goods, allowing routes optimisation and cargo charging a storage element (capacitor, super- capacitor or rechargeable battery). The energy Nowadays, it is possible to design with small size, storage circuit is a key point, since the collected high efficient and low cost, positioning systems such energy is sparse and intermittent, and can be out for as DWLocator [1] by DailyWork or PicoTrack [2] by Telic. These units are usually dependent of an As can be seen in Table 1: Energy sources and the internal rechargeable battery (lasting a few days or typical amount of energy they can produce (adapted from months without recharge) or a non-rechargeable [4])., the expected power collected is about some battery, having a lifetime limited to a few years, mW/cm2 in the case of solar energy while only some such as DWLocator [1] (3 years). Also they are µW/cm2 for the others. characterized by having a high period of messaging Typical Energy
Energy Source
Typical Application
(several hours or even days). Level Produced
The present article proposes a solution to increase the lifetime of autonomous systems in the Small solar panels electronic devices transportation sector, through the collection of external environmental energy (energy harvesting), as well as optimizing the energy consumption of the (heat into electrical device through the use of low power consumption sensors that allow sending information only upon Handheld devices detection of relevant events (beginning and end of or remote actuators the journey, passing through toll (motorway entry RF energy from an opened/closed, theft, etc.) Table 1: Energy sources and the typical amount of energy they can produce (adapted from [4]).

One can conclude that solar energy (captured with a conjunction with a LTC 3588 - Piezoelectric Energy small solar panel), is the most efficient energy Harvesting Power Supply. source. In addition, due to the vibrating environment The storage circuit needs to ensure the collection of inside the vehicle, the mechanical energy (captured a significant amount of energy and high number of by a piezoelectric material or a magnet oscillating charge/discharge cycles, which is not possible with a through a coil) may be a possible solution. Finally, common lithium rechargeable battery. In addition, the thermal and electromagnetic sources have a low the GPRS communications module used, needs power output in a natural vehicle environment, and current peaks of 1A. Two lithium capacitors [6] of will not be considered. 40F each were employed, having high capacity Apart from the study of the sources of energy, it is storage and being characterized by hundreds of also essential to optimize the power consumed by thousands of charge / discharge cycles. Also, they the system, checking the position of the vehicle only are able to provide current peaks of many Amperes. when it is relevant. For this, it is possible to use To ensure that the system is functional even in acceleration sensors (accelerometers), which verify periods of reduced energy production, a non- whether the vehicle is moving, stopped or had an rechargeable lithium battery is used. The device management process is executed by a whenever necessary. Another relevant factor for PIC24FJ128GA310 – Microchip nanoWatt XLP fleet management systems to process is the passage Techonolgy. It receives the information collected by of the vehicle through electronic tolls. the ADXL362 accelerometer (with typical The technology used for toll collection is known as consumption of 3µA) to identify if the vehicle is Dedicated Short Range Communication (DSRC) [5] moving or not. The information captured by the and implies on a tolling infrastructure reader, a few DSRC module and other sensors like temperature, meters away from the vehicle/unit identifier. When door or theft switch, among others are sent to a the identifier "senses"/detects the reader, it wakes, exchanging some frames performing a DSRC Finally, to allow the positioning of the vehicle, a transaction. In this self-sufficient positioning system GPS module FGPMMOPA6H of GlobalTop was the RSU DSRC beacon serve as a trigger to the integrated. For communication, a GPRS module system, starting a data communication through MC55i-W of Cinterion is used. mobile communication informing a cross of toll The results will be presented in the final submission collection stations. DEVELOPMENT
CONCLUSION
After discussing the various elements needed to The tracking system presented in this article uses the solar and mechanical energy of the external positioning system, it is necessary to integrate all the environment to respond to the needs, while making solutions above into one single unit. Figure 1 shows intelligent and efficient management of the energy the block diagram with the main implemented collected. All components were carefully chosen due to its consumption and wakening techniques were implemented to allow the system to communicate only after the detection of a relevant event. The "toll detector" circuit associated to an autonomous device is also an innovation which provides more information about the vehicle's route at fleet management teams. Finally, the online availability of the information collected by the central system will be the last step Figure 1: Developed block diagram. for a demonstration system through open-source and free OpenStreetMaps's platform [7]. In the case of solar energy, it uses a solar panel transducer able to provide a maximum of 112 mW, and a LTC3459-Synchronous Boost Converter for regulation. If there are mechanical sources (vibrations), they are received by a piezoelectric transducer or oscillating magnet through a coil, in REFERENCES
[1] Dailywork – Investigação e Desenvolvimento Lda, DWLocator Localizador Autónomo, [2] Telic – Telematik & Telemetrie, Telic Picotrack – the smallest tracking device for telematic projects, http://en.telic.de/telematics/picotrack/picotrack.html (July 2013). [3] Armstrong, T., Energy Harvesting, Ambient energy Harvesting?, http://www.energyharvesting.net/ (July 2013). [5] ISO 14906, Road transport and traffic telematics – Electronic fee collection — Application interface definition for dedicated short-range communication, 2011. Characterization of Lithium-Ion Capacitors for low-power energy neutral wireless sensor networks, http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6240578 (July 2013). [7] OpenStreetMaps

Source: http://www2.adeetc.isel.pt/cetc13/Book%20of%20Abstracts/Poster%202/cetc2013_submission_105.pdf