The Research On Indoor Positioning System

At present, people's demand for Indoor Positioning System and navigation is becoming greater and greater. For example, users hope to use mobile facility to position and navigate freely. Although technology of outdoor Positioning System is getting more and more prefect, Indoor Positioning System is still at preliminary stage. Thus, the main research of this paper is on Indoor Positioning technology, introduction of presently commonly-used Indoor Positioning System, methods of range finding and analysis of advantages and disadvantages. On the basis of analysis of the actual state of Indoor Positioning technology, working principle and advantages and disadvantages of Cricket Indoor Positioning System based on technologies of ultrasonic waves and radio frequency are introduced in this paper. The system is also improved. Considering the privacy of consumers, they can choose weather to be positioned by themselves. The means of position information pictured by central server is not adopted but to picture coordinates information by each mobile Client. The change of environment should be considered when the distance is calculated, because the change of temperature will in turn change the speed of ultrasonic waves, which has impact on the accuracy of positioning system. In light of errors in the process of system calculation, distance calculation can be corrected by method of least square. When the coordinates is pictured, with the help of a polyhedron formula, improving the simple tri-angle measuring method makes position calculation accurate to reduce the inaccuracy of system. As it is very easy for the single of ultrasonic waves and radio frequency to conflict, to certain extend, improvement of Channel Assignment tactic, prolong random time delay and reduce the quantity of information carried by radio frequency single can reduce conflict between singles, make each node launching more average and lessen the consume of system energy. In the paper, the general design of positioning system based on ultrasonic waves and radio frequency is also introduced. Hardware constitution which is needed by Indoor Positioning at present will be completed. Transceiver Modules of ultrasonic waves and radio frequency are emphasized. The circuit design and principle are explained. The detailed control procedure, in which ultrasonic waves and radio frequency are launched and received, is talked about in the paper.In addition, because people in special places (such as tourists in a museum) need to understand exhibition location information which they face, then the traditional indoor positioning system cannot judge the direction of the face. In accordance with the actual needs, Indoor Positioning System based on the visual technology has been proposed in chapter four of this paper. After reading and studying some materials on Digital coding, image processing and identification technology, the general procedure of Coding principle of two-out-of-five Code, image processing and identification can be also grasped. According to the knowledge of study, positioning principle based on visual technique system is structured. After processing the image and identifying ID Code of mobile tenninal, information from exhibition hall where Image coding equipment is located will be sent to Mobile tenninal through radiofrequency signal on time, controlling related information in broadcasting exhibition area of Mobile terminal. In this paper with the help of Coding rule of two-out-of-five, Coding rule of three-out-of-five is bom and ID Coding procedure of Mobile terminal is also set. For the collected image of mobile terminal, they are handled by such methods as Grayscale, Median filter, Threshold Segmentation and so on. The results from the processing by following steps are also presented. Though the result of identification, it judges the direction of face and transmits the corresponding information to the target to be tested.