Rechargeable Mini Inductive Loop Vehicle Detection Sensor Based On ZigBee

With the increase of the world's economy and the development of urbanization, the transportation issue has already become a universal problem all over the world. Intelligent Transportation System (ITS) is a valid approach to solve the increasing transportation issue. Vehicle detection is one of the key technologies in ITS. The ITS collects and processes traffic data (vehicle flow, vehicular speed, vehicle density and occupancy ratios) from vehicle detection sensors. Inductive loop detector as one type of the vehicle detector is applied extensively, with the characters of stability, high value to cost ratio and feasibility. On the other hand, most of the existing inductive loop vehicle detection sensors have some weak points such as friability of detective loop, huge engineering for setting and traffic interruption during installing the sensor. The design and reality of a new rechargeable intelligent vehicle detection sensor is presented in this paper against these weak points existing now.The emphasis of the paper is placed on the hardware design including the detector circuit, the fast-charge management circuit, the supply voltage supervisor, the interface, parts selecting and parameter setting; the software design including frequency detecting program, anti-jamming, transmit program, the design of the data frame and the network; the power consumption and the experiment. The outstanding of this system lies in the following three aspects:First, in order to reduce the installing project amount and make the loop durable and easily maintaining, the volume of the detective loop is reduced as possible as we can by the research of the coil, magnetic core and the methods of producing the inductive loop.Second, communication in RF (radio frequency) and powered by rechargeable batteries bring on the advantages of getting rid of the feeder cable completely and reducing the installing project amount enormously. ZigBee wireless module which is selected as the RF module is a short-range wireless network technology with the features of easily forming a network, low cost and low power consumption.Third, the purpose of the intelligent management of the energy and transmitter by means of low power MCU is to minimize the power consumption and prolong the working period of the sensor.