Hardware Design And Realization Of Military Electronic Whiteboard Based On Laser Positioning

The electronic whiteboard, a piece of equipment supporting the interaction between people and computers in education and conferences, is now widely used in many fields, such as multi-media teaching, on-line distance education, internet conference etc. With the development of relevant technologies, the electronic whiteboard, by combining with the computer and projector, has evolved into an interactive system, which has greatly facilitated human communication in giving speeches, lectures or presentations in conferences. Having proven itself to be efficient in the educational field, this interactive system also plays an important role in business, political and even military fields.At present stage, there are various kinds of technologies concerning the electronic whiteboard. Some representative examples are technologies of pressure sensors, electromagnetic inductions, supersonic positioning, and CCD scanning, each having its own characteristics and advantages. However, the electronic whiteboard used in military maneuver and command or wars requires a larger writing space and stronger anti-interference performance. Therefore, the current technologies cannot satisfy military needs. On studying the military needs, this paper applies the technology of laser scanning technology which has a better anti- interference performance to the electronic whiteboard, accomplishes the hardware design of military electronic whiteboards based on laser positioning and realizes the function to trace handwriting.This paper is divided into six chapters. Chapter one and two introduce the background for the research on military electronic whiteboard, and the positioning theories of the laser scanning technology. Chapter three, four and five give a detailed account of the research work done by the author. The last chapter, chapter six, provides a conclusion for the thesis.The first chapter gives the background information for research on military electronic whiteboard, and then makes a brief description of the structure of the military whiteboard system and the functions of its parts. And then it goes on to state the major content and work included in this paper.The second chapter introduces theories of wireless positioning and laser measurement, with the focus on the positioning theory of laser scanning, and illustrates the positioning methods used in military whiteboard.Chapter three elaborates on the design and realization of the laser scanning system. It firstly presents the design of the writing system and calibration devices, including the selection of reflectible materials, design of the pen, eraser and calibration band. Then it expounds the design and optimization of optical devices, including the selection of components and laser emission modules, design of the drive circuit and optical devices. Moreover, it provides a systematic explanation of the ways to optimize optical devices and points out some problems worthy of notice. On reintroduction of the design and realization of laser receiving circuit, the rest part of this chapter is devoted to the solution plan for pen-up movement identification in laser scanning.Chapter four dwells on the design of signal processing system of the military electronic whiteboard. It introduces the design of the power circuit, the design of DSP processing unit its peripheral circuit, which further include the designs of the memory interface, analog/digital conversion circuit and communication interface. Then it discusses the control and realization of the polygon scanner motor and the drive process of laser emission circuit, followed by an elaboration on the design of anti-interference circuit in the end.Chapter five is dedicated to the arithmetic design of handwriting tracing and its realization of DSP. It sets forth at the beginning the subprogram of time delay identification, which is achieved by adopting different methods to collect reflection signals of the laser scanning systems both on the left and right. Then, it introduces subprogram of coordinates calculation. As there is no tangent instructions in TMS320VC5402 for coordinates calculation, here the author uses Taylor's series and trigonometric equation to get the tangent value. And the authentic results of writing are given in the end.Chapter six presents a final conclusion, and points out the direction for future research and work.The creative part of this paper lies in the hardware design of the military whiteboard based on laser positioning, and the realization of the handwriting tracing function within the range of 4m by 4m.The major contributions of this paper are listed below:(1) The utilization of red visible laser emission modules reduces the difficulty in debugging optical devices. Furthermore, the proposition of systematic and feasible methods of optimization enhances the accuracy in calibrating optical circuits.(2) Both the design and optimization of a better laser receiving circuit with more stable performance are accomplished.(3) It puts forward a plan for pen-up movement identification, which preliminarily solves the problem of dragging-stroke handwriting in laser scanning by combining accurate calibration of optical circuits with handwriting tracing arithmetic.(4) It designs handwriting tracing arithmetic, including the design of subprograms of time delay identification and coordinates calculation, and their realization in DSP.(5) It designs print circuit board according to the theory of electromagnetic compatibility, and improves the anti-interference performance of military electronic whiteboard.However, there are still some problems concerning the manufacture of military whiteboards remaining to be solved.(1) To simplify the hardware design of the signal processing system so as to better the maintainability of the system and to minimize the chances of systematic fault.(2) To conduct a standardized electromagnetic design of the print circuit board so as to strengthen the anti-interference performance of the system.(3) To study the influence that high-frequency noise has on the laser-scanning positioning technology, within the context of simulated warfare conditions.(4) To carry on further study on the case of pen-up movement identification in order to achieve the goal of identifying the pen-up movements under the conditions of high frequency pen-up and pen-down.(5) To solve the problem of handwriting infidelity.