| Indoor positioning system (IPS) is a system aiming to acquire the position information of indoor objects. IPS makes up the positioning accuracy deficiency of GPS in indoor environment. With the development of Internet of Things and mobile internet, people’s need of position and navigation in complex indoor environment is increasing fast, at the same time, IPS has a broad application prospect in areas such as public security and mobile e-commerce. At present, the positioning technology of IPS mainly includes RFID, Bluetooth, Wi-Fi, UWB, ZigBee, optics, ultrasonic, infrared, magnetic field, etc. There are some defects of IPS with single positioning technology, such as strong burden requirement, poor scalability and robustness, low positioning accuracy, long response time, and so on. Therefor integration of multiple positioning technologies is the developing direction of IPS.IPS based on force based touch screen technology is researched in this thesis. Force based touch screen technology, also known as zTouch, orginates from F-Origin company in the United States. The principle of zTouch is to set up multiple pressure sensors around the corner under a rigid panel, and to acquire the information of force perpendicular to the panel by sensors when object touches the panel, and to calculate the position according to the different values of each sensor point. zTouch can make up the inadequacies of other positioning technologies with the advantages of environmental robustness, persistence, burden free requirement, three-dimensional information awareness, high positioning accuracy, etc. In this paper, the main work is as follows:Firstly, the positioning principle is researched. In this part, the positioning mathematical model of four fulcrums unit is built and the positioning formula is derived at first, and then the dead zone problem is analyzed, and the influence of tilted platform on positioning accuracy is explored. At last, the positioning algorithm of the platform composed of multiple four fulcrums basic units is presented.Secondly, the positioning system is constructed. The positioning system is divided into position display subsystem, motion control subsystem and remote monitor subsystem. The position display subsystem includes a70×70cm2positioning platform which has16pressure sensors and signal amplifying circuit modules,4pieces of square glass, and a data acquisition card which is NI USB-6259(BNC) to acquire16sensors’data, and a computer with Lab VIEW software to calculating and displaying the location and trajectory information. In motion control subsystem, a small robot, Micromouse615added bluetooth function, is choosen as the controlled and located object. The Micromouse615is wireless controlled through the computer when it motions on the positioning platform, to avoid producing side force by directly contacting Micromouse615, which will have an influence on positioning accuracy. Remote monitor subsystem is to provide location service for Android devices by using the cross-platform network communication function of Lab VIEW. Android mobile phones can view the object’s position via the Internet.Lastly, the positioning system is tested. The result proves that the system has realized the wireless motion control of single Micromouse615, location and path display and remote monitor of positioning information. In addition, the platform tilted situation is also tested through leveling software, and the result proves that a tilted platform especially with "weak leg" will affect positioning accuracy. Under the condition of free "weak leg", positioning precision of the system reaches2cm in the research situation. On the basis of positioning function, the further function of motion control based on the given location is realized. In other words, Micromouse615automatically moves from the current location to the given target position on the platform. The experimental results show that the average error of position control reaches1.2cm in the single zone situation and5cm in the all zones situation. |
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