Research And Development Of Optical Touch System Based On Four Cameras

With the popularity of smart phones, tablet PCs and other smart terminal equipment，people need to be more flexible and convenient way of human-computer interaction, all bornout of touch technology. Wherein the optical touch technology due to its fast response, touchaccuracy high, has been widespread concern and research. Optical touch technology researchand innovation and diversification of development programs to solve the optical touchtechnology in a number of critical issues, the promotion of optical touch technology todevelop a low cost, high performance optical touch products are essential.This paper through research and learning related touch technology, in view of the largesize of the screen touch is proposed based on ARM Cortex-M3kernel architecture32-bitmicro-controller based on the four road camera optical touch system development plan. It hasthe characteristics of simple construction, low cost, stable performance and suitable for largesize screen and so on.In terms of functional structure, the system consists of image acquisition module, dataprocessing module and main control module. Data processing module will preprocess theimage data obtained by four road cameras, and then sent to the main control module tointegrate and to calculate the contact position coordinates, and the send it to the host computerto interact. In terms of hardware platform, system uses LPC1768micro-controller as the maincontrol chip, LPC812as the processor chip, OV7675image sensor as the CMOS opticalsensor of the camera. In order to improve the development efficiency, a secondarydevelopment tool called the I2C adapter has been used.In terms of software design, the design process of the entire software system is analyzedin detail through introducing the software program of the image acquisition module, dataprocessing module and the main control module. This paper independently developed a set ofupper computer software which was used to improving the efficiency of development.In terms of camera calibration, this paper combined and improved two classic cameracalibration algorithms of Tsai two-step method and Zhang Zhengyou plane method, and thendeduced the calibration process, then discussed and analyzed the calibration results. Thispaper described some key parameters of the camera and their measurement methods were introduced.