| The wireless transportation network built on Wireless Networked Sensor (WNS),with interactions among driver, vehicle, and road in it, has become a cutting-edgetechnology which will guarantee a safe and high-efficient operation.We have developed a platform integrated with hardware and software. LayerDivision Multiplexing (LDM) is adopted into our hardware platform which includescomplete modules in need; on the other hand, the real-time kernelμC/OS-Ⅱis portedas software platform to manage the running of application programs. As a whole, itprovides a general development kit for the application research of WNS.Upon the general platform, an application-specific traffic parameter surveillancesystem has been developed: based on WNS technology, a thin-film magnetoresistivemagnetic field sensor is used, and we also add the back-off scheme, flow and speedalgorithm, and synchronization mechanism. The enclosed sensor node, 10.3cm indiameter and 3cm in height, makes the deployment of the system convenient andflexible. Sensor nodes work at self-adaptive mode and 2.7% duty cycle, and canminimize power consumption. Touch screen was designed in our control node toconfigure and control the complete surveillance system.On a real site, we have measured the repeatability and consistence of our sensornodes. A 98.7% vehicle counting rate was obtained in a small sample of 231 vehicleswhich proves the feasibility of our flow algorithm, and the speed algorithm was alsotested. Results show that the sensor nodes employing low power and short-distancewireless technology can be used for fixed or temporary traffic monitoring. Merginginto the mature wired networks, it can also provide real-time data for traffic controland prediction. |
