| Currently, unltrasonic sensor is a mature technology in the world wide, this sensor has follow adventages:high measurement precision, low cost and easily communicate with computer. Unltrasonic sensor is widely used in oil, agriculture and hydraulic industries for wter level detection, but less in household area. In this paper an unltrasonic sensor water level detection system is designed for household washing machine.In this paper, firstly introduce the unltrasonic sensor how to work and development history. Then it shows the water level sensor disadvantages in current household washing machine. Because the advantages of unltrasonic sensor, the unltrasonic water level detection is the better solution for current household washing machine.The basic research information & detail requirement be given for this application. Then is the mechanical design content, the most important task is how to keep water level stable? Next is electrical design content, it includes hardware and outside. The task is the compatibility with current control system, it should be considered for the application and promotion in the future. Softeware design includes temperature compensation & noise filtering. Temperature compensation can solve the environment temperature changing problem. Noise filtering is for fixing internal and external noise. Internal noise comes from unltrsonic sensor itself, and external noise comes from outside environment. Noise filtering can improve the system stability and precision.After that, start installing and debugging the system, in this process we found thers is a deviation between measurement value and real value. Some deviation be found by mathematical tool, so introduce a corrected formula into software for solving the deviation.At the last, use FMEA tool to evaluate the safety risk for this system. Then this syatem is released for marketing after the evaluation. |
