Some real-world applications of wireless sensor nodes

Steven D. Glaser, Shih-Chi Liu
2004 Smart Structures and Materials 2004: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems  
This paper presents two case histories of the use of wireless sensor Mote technologies. These are devices that incorporate communications, processing, sensors, sensor fusion, and power source into a package currently about two cubic inches in size -networked autonomous sensor nodes. The first case discussed is the November, 2001, instrumentation of a blastinduced liquefaction test in Tokachi Port, Japan. The second case discussed is the dense-pak™ instrumentation of the seismic shaking test of
more » ... full-scale wood-frame building on the UCB Richmond shake table. The utility of dense instumentation is shown, and how it allows location of damage globally unseen. A methodology of interpreting structural seismic respose by Bayesian updating and extended Kalman filtering is presented. It is shown that dense, inexpensive instrumentation is needed to identify structural damage and prognosticate future behavior. The case studies show that the current families of Motes are very useful, but the hardware still has difficulties in terms of reliability and consistancy. It is apparent that the TinyOS is a wonderful tool for computer science education but is not an industrual quality instrumentation system. These are, of course, growing pains of the first incarnations of the Berkeley Smart Dust ideal. We expect the dream of easy to use, inexpensive, smart, wireless, sensor networks to become a reality in the next couple of years. We report on two full-scale field applications of Motes -what we tried to achieve, what went right, and what went wrong. The first case is the Tokachi Port, Japan, campaign where we installed twenty 2-D accelerometer Motes for the blastinduced liquefaction experiment in November, 2001. The second case study is the instrumentation of a full-size three story wood-frame building that underwent strong shaking on the UCB Richmond Field Station seismic shake table in December, 2001. These were the first field applications of Mote technology, and much was learned that has led to recent hardware and software improvements. We have worked directly with Professor Culler, author of TinyOS, and Prof. Pister, builder of smart dust, since the smart dust idea took form during the summer of 2001. Prof. David Culler beautifully describes the Berkeley Smart Dust ideal:. Spread thousands of wireless sensor nodes casually over an arbitrary area of interest. They self-organize into a network conveying arbitrary information from any point to any other at whatever bandwidth is demanded...while operating at incredibly low energy usage (i.e, off most of the time) to run for years on small batteries and harvested energy...and being extremely responsive in times of key activity...without ever bothering you about design considerations, intended usage, faults, or constraints. THE MOTE Hardware The Motes are simple, robust, and are designed to be built from readily available components. The basic structure of the original Mote baseboard (the "Rene") consists of an Atmel AT90LS2343-4SC microcontroller, and the RFMonolithics TR1000 amplitude-modulation 916.5 MHz Hybrid ASH Transceiver (Atwood et al., 2000). The devices were fitted with a Microchip Tech Inc. AT90LS2343-4SC IC serial EEPROM to act as non-volatile flash memory. The Rene boards were powered by two AA-sized alkaline batteries and did not have any on-board power control circuitry. The most common antenna was an 80 mm long copper wire. Some of the later Crossbow-packaged devices used a stubby 80 mm whip. At the time there was little direct optimization of hardware variables such as antenna design, micro-controller choice, or memory type. For instance, the Atmel micro-controller was chosen over the StrongArm and TI MSP430 because there was a gcc (free) compiler available through Gnu. We now see that the MSP430 is a much more powerful controller (16bit vs. 8-bit), uses less power than the Atmel, has better internal analog-to-digital convertors, has pre-implemented UARTs, etc. Dust Inc. and University of Twente currently make excellent use of the TI chip. The detachable sensor board incorporated a two degree of freedom Analog Devices ADXL202e 2g MEMS accelerometer, and connected to the main board through a Hirose H-series 51-pin, 1 mm header. The Intel Laboratory at Berkeley, directed at the time by Prof. Culler, later tried to develop a five-sensor weather board. This board is currently being sold by Crossbow Inc. as the MTS420CA sensorboard. The weather board holds an ADXL202e accelerometer, the Sensirion SHT11 humidity and temperature sensor combination, the Taos TSL2550d light intensity sensor, and the Intersema MS5534AP pressure and temperature sensor combination. TinyOS (tiny operating system) A key innovative capability of the Mote is its pervasive support of fluid software, i.e., 1) it has the ability of processing, storage and data management functionality; 2) it can arbitrarily and automatically distribute itself among information devices and along paths through scalable computing platforms integrated with network infrastructure; 3) it can compose itself from preexisting hardware and software components; 4) it can satisfy its needs for services while advertising the services it can provide to others; 5) it can negotiate interfaces with service providers while adapting its own interfaces to meet components it serves. Recent progress in this area is the development of TinyOS, an embedded operating system for Motes. TinyOS migrates the event-based model being developed for clusters into a very light-weight form for Motes. The heart of TinyOS (TOS, 2004), communications, must be able to scale to thousands or millions of nodes within a single network and be flexible to dynamic topology changes. It must also be tolerant of failures due to lossy links or
doi:10.1117/12.539089 fatcat:a3irchbmonbcpi4yb4uswxpgue