关键词: android多点触摸屏, 校正, 信噪比（SNR）, 人机界面（HMI）

Abstract: In order to design a new practical industrial human-machine interface, a touch input system design way based on a five-point touch calibration and a median average filter algorithm is proposed. The system uses a five-point touch calibration to calculate the correction factor based on a sampling of five points of the touch screen as a touch-screen calibration parameters; based on mXT224 controller, it utilizes the average median threshold way to filter white Gaussian noise and spike noise, and then effectively corrects calculation of multi-point input, step by step uploads input coordinate information, and ultimately passes information to the upper application. The tests show that the noisy environment based on the optimization of the Android multi-touch input system can maintain a high signal to noise ratio（over 80∶1）, and support with gloves or a stylus to touch input with the response time of less than 10 ms, which is accorded with the industrial Human-Machine Interface（HMI） design requirements.

Key words: android multi-touch screen, calibration, Signal to Noise Ratio（SNR）, Human-Machine Interface（HMI）