Study On Technology Of Touch Point Detection And Positioning In Large Interactive Surfaces

As the technology for input device,touch point detection and positioning technology of large interactive surfaces can make the interaction of application system in virtual scenes more flexible,diverse,lower-cost in order to achieve accurate input of the device.Touching point detection and positioning system of large interactive surfaces is a comprehensive positioning system integrated with computer technology and sensor technology.As flexible and diverse terminals,it can be applied to military,medical,education,and other fields.As a result,it has bright prospects.In this paper,a touch point detection and positioning system on two-dimensional surfaces are designed to achieve the detection and position of touch points on large interactive surfaces by combining the laser ranging positioning system and the scanning device.After comparing the positioning methods and the technical principles of the laser ranging technology and the image based positioning technology,due to the high measuring accuracy,the high anti-interference performance and the low cost of laser ranging technology,the author uses laser ranging positioning technology for positioning touch points,and employs the TDC-GP22 chip to improve the accuracy of time difference measurement to achieve high accuracy positioning of touch points,and gives detailed description of the timing principle and the work process of the TDC-GP22.After comparing scanning by swinging a two-dimensional flat mirror,parallel beam scanning and scanning by rotating a polyhedral reflecting prism,the author uses the scanning method by rotating a polyhedral reflecting prism whose scanning frequency can be increased to achieve the detection on a two-dimensional surface by using a laser ranging system.With the detected value of distance by using laser ranging technology and the rotated angle of the scanning device,the detailed position of a touch points on a surface can be computed.In the system,the MSP430 main-control chip is used to control the main modules,such as the laser emission module,the laser reception module,the time difference measurement module and the scanning module to achieve the detection and positioning of touch points on a two-dimensional surface.The application of the TDC-GP22 improves the positioning accuracy of touch points and achieves high accuracy positioning and measurement.The paper provides the design and making methods of the main hardware modules of the system,as well as the circuit diagrams of the hardware.The result shows that the solution is feasible,which can be used to achieve the positioning of single touch point on a large surface,and that the application of the TDC-GP22 to measurement brings high measurement accuracy.