Nondestructive System Of Watermelon Maturity Based On MEMS Accelerometer

Recent years, with the improving of people's material living standard, the demand for the quality of fruits and vegetables is also increasing. Watermelons as one of the most important economic crops in China, which has become a large-scale production and become one of the preferred cash crops for rural industrial structure adjustment and for farmers to increase wealth. The majority of consumers are not able to correctly choose mature watermelons, the estimate of maturity of watermelon is still using the traditional identification of calculating, watching, listening, measuring and other methods. These methods, depending on personal experience in most time, are difficult to make accurate estimation of maturity of watermelons. The price of maturity testers is very expensive; this greatly limits the popularization and application of nondestructive maturity testers.After analyzing the existing non-destructive testing technology of the watermelon maturity and the research situation of home and abroad, this paper designs a portable watermelon maturity based on MEMS accelerometer, and the instrumentation has been overcome the shortage of non-portable, also reduce the cost of the system. This design is composed of the MEMS accelerometer with an adjustable elastic tape and a small base box in which there is circuit board of the system, and the key and the LCD is on the surface of the base box. Compared with other maturity testers, this design has many features such as:we import the MEMS technology and make the system higher integration. During detection of Watermelon maturity achieve non-destructive testing. The single chip processed the vibration and the quality signals and calculated the maturity index and then compared with the maturity level classification before detect the maturity and classify it. The result will show on the LCD. The testing procedure takes short time and the accurate result. It doesn't need any other supplementary instrument. The design has high Portability and low cost.This design detects the watermelon maturity nondestructively based on the principles of acoustics and vibration and use the MEMS accelerometer as the conversion device of the vibration signal. It used MEMS accelerometer as the conversion device of vibration signal and used the function of Digital Signal Processing of the SPCE061A single chip to analyze them. At last used computation formula for maturity index to calculate the maturity index of watermelon and classified them according to the classification standards.This essay has mainly completed the design of the hardware circuit, software program and the algorithm. The hardware circuit includes the design of peripheral circuit for CPU, the circuit for collecting signals, the power supply circuits and the circuits for LCD and keys. The algorithm for data processing of the single chip system includes calculation of first-order natural frequency, algorithm for FFT, attack, maturity correction and weight. At the end of essay we tested the system, analyzed the result and put forward the improvement plan.