【正文】 ing the builtin wireless transmitter in the Tmote Sky. Fig. 3 Tmote Sky H. Tmote Key Features ? 250kbps IEEE Chipcon Wireless Transceiver ? Interoperability with other IEEE devices. ? 8MHz Texas Instruments MSP430 microcontroller (10k RAM, 48k Flash Memory) ? Integrated ADC, DAC, Supply Voltage Supervisor, and DMA Controller ? Integrated onboard antenna with 50m range indoors / 125m range outdoors ? Integrated Humidity, Temperature, and Light sensors ? Ultra low current consumption ? Fast wakeup from sleep (6μs) ? Hardware linklayer encryption and authentication ? Programming and data collection via USB ? 16pin expansion support and optional SMA antenna connector ? TinyOS support : mesh working and munication implementation ? Complies with FCC Part 15 and Industry Canada regulations ? Environmentally friendly – plies with RoHS regulations [4]. I. ZigBee Wireless Technology ZigBee is a specification for a suite of high level munication protocols using small, lowpower digital radios based on an IEEE standard for personal area works [6] [7]. ZigBee devices are often used in mesh work form to transmit data over longer distances, passing data through intermediate devices to reach more distant allows ZigBee works to be formed adhoc, with no centralized control or highpower transmitter/receiver able to reach all of the devices. Any ZigBee device can be tasked with running the work. ZigBee is targeted at applications that require a low data rate, long battery life, and secure working. ZigBee has a defined rate of 250kbps, best suited for periodic or intermittent data or a single signal transmission from a sensor or input device. Applications include wireless light switches, electrical meters with inhomedisplays, traffic management systems, and other consumer and industrial equipment that requires shortrange wireless transfer of data at relatively low rates. The technology defined by the ZigBee specification is intended to be simpler and less expensive than other WPANs, such as Bluetooth. J. Types of ZigBee Devices ZigBee devices are of three types: ? ZigBee Coordinator (ZC): The most capable device, the Coordinator forms the root of the work tree and might bridge to other works. There is exactly one ZigBee Coordinator in each work since it is the device that started the work originally. It stores information about the work, including acting as the Trust Center amp。 and active sensors [3]. The sensors are implemented in this system placed beneath the roads in an intersection or on the lane dividers on each road. The sensors are active obstacle detectors that detect the presence of vehicles in their vicinity. The sensors are set in four levels on each road signifying four levels of traffic from starting from the STOP line. The fourth level indicates high density traffic and signifies higher priority for the road to the controller. The sensors required for obstacle detection can be either ultrasonic or Infrared LASER based sensors for better higher efficiency. B. Motes A mote, also known as a sensor node is a node in a wireless sensor work that is capable of performing some processing, gathering sensory information and municating with other connected nodes in the work. The main ponents of a sensor node are a microcontroller, transceiver, external memory, power source and one or more sensors [3]. Fig. 1 Block Diagram of a Mote C. Need for Motes The primary responsibility of a Mote is to collect information from the various distributed sensors in any area and to transmit the collected information to the central controller for processing. Any type of sensors can be incorporated with these Motes based on the requirements. It is a pletely new paradigm for distributed sensing and it opens up a fascinating new way to look at sensor works. D. Advantages of Motes ? The core of a mote is a small, lowcost, lowpower controller. ? The controller monitors one or more sensors. It is easy to interface all sorts of sensors, including sensors for temperature, light, sound, position, acceleration, vibration, stress, weight, pressure, humidity, etc. with the mote. ? The controller connects to the central controller with a radio link. The most mon radio links allow a mote to transmit at a distance of about 3 to 61 meters. Power consumption, size and cost are the barriers to longer distances. Since a fundamental concept with motes is tiny size and associated tiny cost, small and lowpower radios are normal. ? As motes shrink in size and power consumption, it is possible to imagine solar power or even something exotic like vibration power to keep them running. It is hard to imagine something as small and innocuous as a mote sparking a revolution, but that39。 《現(xiàn)代控制理論》 題 目 智能交通信號(hào)控制 學(xué)生姓名 學(xué) 號(hào) 學(xué) 院 專(zhuān) 業(yè) 指導(dǎo)教師 二Ｏ一 三 年 12 月 15 日 Intelligent Traffic Signal Control Using Wireless Sensor Networks and Vigneshwar. Santhanam Abstract:The growing vehicle population in all developing and developed countries calls for a major change in the existing traffic signaling systems. The most widely used automated system uses simple timer based operation which is inefficient for nonuniform traffic. Advanced automated systems in testing use image processing techniques or a