August 1, 2007, in Minneapolis I-35W Mississippi River bridge collapsing, this caused 13 people were killed and more than 100 injured in the tragedy reveals a serious problem facing the nation. Most transport infrastructure that people rely on the aging, urgent repair. In fact, the FHWA (Federal Highway Administration) as early as 2006, the country has more than a quarter of the bridge included in the list of problems, some structural defect exists, while others have lost their function. How can we extend the life of these facilities at the same time to avoid a repeat of such tragedies?
Only do visual inspection clearly enough: I-35W bridge before the accident had already passed the routine visual inspection. More innovative and comprehensive inspection method is the use of sensors to monitor the structural vibration, and then send the monitoring results to the data collection point, analyze when, where there may be a problem. In the past, the bridge for such detailed structural analysis is not only difficult, but also costly.
For each sensor transmitter power usually need foot heavily wiring; even if operation of the device without power and communications wiring can be achieved, but also need routine maintenance, in order to replace the battery. For maintenance requirements, the sensor can not be placed into those hard to reach, there may be monitoring very important sites, making it impossible to collect sufficient data, security also will be greatly reduced.
However, AdaptivEnergy company is introducing a new technology it is possible to remote monitoring and security architecture becomes simple and economical. AdaptivEnergy''s Joule-Thief technology does not depend on batteries to run, but to collect and store energy vibration, and then use the stored power-driven microprocessor, various sensors and a radio transmitter. Texas Instruments (TI) ultra-low power microcontroller (MCU) and radio frequency (RF) technology to collect vibration data, control the overall operation of the system, and periodically sends related information to a collection point.
Joule-Thief possible to collect vibration energy of the vehicle and other vehicles through the bridge when generated, then sends the data of all sensors on the bridge to a collection point, and in this analysis, which monitor the structure of firmness. Joule-Thief-driven wireless sensor that is able to run without maintenance for years to collect and send important information to help protect the life of the bridge, buildings, vehicles and machinery and equipment and save costs.
Implement ambient intelligence
Joule-Thief is a kind of vibration energy can collect and use new technologies. Because everything around us there are different levels of vibration, so almost everything can become a potential source of energy. Perhaps the most famous contemporary energy harvesting method is the use of solar panels and wind turbines as a source of electricity, but there may be the oldest use of water turn the wheel. In order to meet the needs of small-scale electricity, radio frequency identification (RFID) tags Wireless charges, warehouse pallet tags, credit card system (wave-and-go credit card) and many other applications will sometimes use radio wave environment. These identification cards to receive energy from the passive RFID reader, and then send back a response to identify low energy.
In addition, Joule-Thief technology can also collect other architectures machinery, vehicles, buildings and bridges and other produce such as general mechanical vibration energy. Small sensor transmitter may be mounted to the door, the electric motor base and other small space. Sensors in these places no batteries, power lines or communication wiring work can be carried out, but also be able to run down indefinitely without the need for maintenance. Therefore, this technique is particularly suitable for those who need long life, high temperature operating personnel or difficult to access applications. In addition, it can be used as if environmental conditions require effective method dormant electronic products, "wake up."
When ready to design AdaptivEnergy Joule-Thief technology, its engineers in the development work will start soon it will be met with a significant impact on the final result of the selection.
In the early development work, AdaptivEnergy also recognized the need to use very low power consumption and sophisticated signal processing capabilities to achieve its design goals. One reason is that, at lower levels of vibration energy harvesting energy equipment collected is very limited, so the sensors used to gather information, the control system is running and sends microcontroller and RF transceiver related information must rely on only a small amount of power It will be able to operate normally.
Another advantage of using modern ultra-low power microcontroller is able to wake up immediately from standby and off. and especially the MSP430 MCU can be woken up from standby power consumption during operation minimal power consumption in standby mode is only negligible in 0.5? A, in less than one microsecond. MSP430 MCU mixed signal integration helps reduce the total number of components AdaptivEnergy, thereby improving data monitoring and processing performance while reducing costs and shorten time to market.
After comparing a number of performance and price of various options, AdaptivEnergy selected TI''s MSP430 MCU and radio frequency (RF) transceiver chip set, because they can take advantage of low battery power collector to collect and provide the highest possible storage and processing transmission capacity. 2 Figures 1 and accumulated energy and recovery time compared with the input amplitude.
The key to low-cost ambient intelligence is driven by the energy harvesting sensor transmitter, this intelligence can sense, monitor and report on factories, offices, vehicles, homes, shopping malls, transportation hubs, etc. - in short, including almost all of the human environment and the natural environment, including health. In the hundreds of millions of wireless sensor nodes are installed each year, more and more nodes by the kinetic energy collected to drive.
Structure for bridge safety monitoring is not only very important, high-rise buildings and other buildings and gymnasium same is true, because it is difficult to be found in the aging columns and beams is likely to lead to disastrous consequences. Motor factory machinery and other equipment, the sensor can alert staff to pay attention to bearing wear and the need to maintain other issues, its forecast, which helps to avoid the higher cost of the failure to extend the service life of the equipment.
The potential rewards are very generous: It is estimated that the information from the device industry, the United States each year for mechanical maintenance costs of more than $ 1.3 trillion, and assets by monitoring carried out preventive maintenance can save tens of billions of dollars a year, equivalent to saving almost 5% of the maintenance costs. Improve other savings mainly from the effect of the operation of the machine, reducing the frequency of replacement of equipment and plant shutdowns during idle equipment and other aspects.
Cars powered by wireless vibration sensor can improve the safety performance and also help to mitigate each vehicle on the assembly line weighing 300 to 500 pounds of wiring. Powered by the vibration of the tire pressure monitoring system will be used in the current system battery from the historical stage.
Than the vehicle, energy harvesting sensor for the importance of the aviation industry is worse. Among other functions, such sensors also for the integrity of the aircraft framework for security monitoring, and even can be monitored from the dead, hidden space or high temperatures inaccessible places. Commercial aircraft, per foot of wire will generate approximately $ 2,000 of installation and lifetime maintenance costs, not including the cost of fuel or spare battery consumption. If you no longer need wires and batteries, powered by the vibration and has a wireless transmission function of the sensor can save a lot of money for cost-sensitive industry, and in this industry, the weight, space and fuel consumption to a minimum is very important .
Motion for Joule-Thief energy harvesting may be derived from sources other sports outside of mechanical vibration, such as pressure or airflow; and its output, except for the vibration sensor power supply, but also for temperature, chemical, light, humidity, and other environmental conditions sensor powered. Not only can achieve energy cost savings of automated sensor-based, but also to the family and the workplace become more environmentally friendly and comfortable.
Active radio frequency identification carriages and containers can be vibration-powered devices are used to assist tracking (RFID). This technique may eventually be used in human clothing, in order to reduce the number of batteries we carry, this application has a particular importance in alleviating the load for soldiers on the battlefield.
Efficient Energy Harvesting
Joule-Thief core technology is a piezoelectric ceramic intelligent energy beam (Smart Energy Beam), can react to the motion and vibration into energy to be stored for subsequent use. AdaptivEnergy''s Ruggedized Laminated Piezo (RLP) technology for pre-stressing a piezoelectric ceramic material, in order to achieve more than the power and size of the ceramic stress and non-weight ratio. For ceramics and metal substrates bonded together polyimide advanced ceramic technology allows for up to 4 to 10 times the stress is applied, which can improve power. In addition, RLP technology also enables energy beam is able to sense the movement of the hand can not feel, so that a wide range of vibration spectrum can effectively collect energy.
Because Joule-Thief energy beam is scalable, it can be applied according to the power demand they be made of various lengths and widths. AdaptivEnergy has developed a much higher efficiency than conventional rectifier and storage capacitor technology electronics, electrical energy can be stored for many hours. When necessary, it can even be stored in a mechanical static environment, enabling the collection of the generated energy. In addition, if the relevant hungry applications require more energy storage, the DC output device can also be fed to the battery charging circuit.
Ultra-low power control and transmission
Based on active intelligence and communications by the MSP430F2274 MCU and CC2500 RF transceiver chip set consisting of perfectibility RLP Smart Energy Beam and collection electronics. CC2500 RF transceiver supports reliable, low-cost digital wireless applications in the 2.4GHz band. MSP430 MCU with extremely low power consumption in standby mode and work. The system shown in Fig.
Less than 1 microsecond fast wake-up standby mode can achieve fast response, and system-on-chip (SoC) integrated AdaptivEnergy help companies save space and board costs, while providing for a variety of ambient intelligence applications maintenance-free wireless sensor. Integrated analog to digital converter (ADC) with pulse-width modulation (PWM) output simplifies AdaptivEnergy sensor system is connected to an external circuit design, clock and diverse programs and I / O can improve embedded control flexibility. When the sensor transmitter for larger systems, flash memory is used for sensing, communications and other functions easily develop and upgrade the algorithms and control software.
Energy harvesting is an emerging field of power technology, the technology can make use of the building framework, as well as the vehicle''s inherent mechanical vibration to generate electrical energy without wires and batteries to drive the sensor, so that not only meet the needs of large-scale wind and solar systems, but also to meet small-scale demand for sensors and other devices. The method described in this article can achieve broader environmental intelligence, improve security and reliability while reducing weight, space, and installation and maintenance costs of a variety of applications.

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