Research On A Ranging System And Communication Mechanism For Indoor Ultrasonic Location

The indoor ultrasonic location system makes the real-time position information receiving become practical. Its application involve to domains and so on car device, individual navigation, emergency positioning, game interactions, and vehicle management. Especially, it gets a broad application in the robot navigation and control of small mobile car. Study of the indoor ultrasonic location system always takes much attention of the researchers at home and abroad. Indoor location demands highly of positioning information, which should reach an accuracy of the centimeter degree and be stable, confidential, low-cost and the like. Therefore, it is a meaningful work to design and realize the indoor ultrasonic location system.The paper designs and realizes an indoor ultrasonic RF location system,it contains RF synchronous ultrasonic range system and a communication mechanism to reduce collision of ultrasonic and RF. Firstly, the system ranges some reasonable transmitter nodes on the ceiling, calculates coordinates of transmitter nodes through referring to three-D coordinate system, and saves them in the memory of the transmitter nodes. Secondly, it makes the robot or the small mobile car to be positioned take the receiver node. Every transmitter node inspects the information road periodically and it could transmit RF and ultrasonic signals if the information road is free. Upon receiving RF signals, the receiver should start inspecting ultrasonic signals and inspect if there are more than one RF signal. If there is only one RF signal, it is probable to estimate the distance from the transmitter node through the time difference of signal arrival to the receiver, and improve the accuracy of the estimated distance by the choice of proper distance transmitter information. Thirdly, using the data of distance more than three groups from the transmitter to the receiver, the system could calculate the most recent location of the receiver node by positioning calculations. Finally, the location information is applied in other modules.The work the studier mainly accomplished is as follows:(1) Put forward the location scheme based on indoor ultrasonic RF location system through a survey of many kinds of location technology and schemes;(2) Designed a control circuit of ultrasonic transmitting, receiving, power source, string and micro-controller;(3) Made a corresponding circuit board;(4) Designed a communication mechanism of transmitters'random delay, receivers'inspection collision and choice of proper distance information because of signal collision easily caused by indoor ultrasonic and RF transmitting;(5) Checked it by experiments and Analysis of the Results.