Design Of Intelligent Electronic Analytical Balance Based On MSP430F449

Electronic analytical balance is the high-precision instruments for mass measurement and it is widely used in national defense, scientific research, trade, chemical, pharmaceutical, electronics, metallurgy and other fields. Electronic analytical balance is weighing with high accuracy and fast response, good stability, automatic calibration, easy to operate and so on.In this thesis, the electronic analytical balance is designed by using low-power single-chip MSP430F449 as the information processing core and high-precision 24-bitΔ-ΣA/D converter CS5532 for signal acquisition unit. The technology of data pre-processing, non-linear correction, automatic temperature compensation and smart zero-tracking is adopted to enhance its accuracy and stability.Firstly, a brief introduction is given, including the development history, the classification and the development trend at home and abroad of the electronic analytical balance. The significance of this research is indicated. The system composition and the electromagnetic force balance sensor of the working principle of electronic analytical balance are analyzed, The design of electronic analytical balance system sensor and analog circuits, data acquisition circuit and the circuit design of single-chip microcomputer system was introduced.Secondly, the system analysis of electronic analytical balance software design was discussed, which includes functional requirements and modular software design. The methods of Modular programming for signal input module, man-machine interface and data-processing module are given in details.The electronic analytical balance is designed with tare, weighing, calibration, data storage, communications, automatic zero-tracking, fault self-diagnosis, performance testing and other functions.And also the virtual PC operation panel function is completed.Thirdly, the information processing methods of electronic analytical balance are studied. Adaptive average filtering algorithm and the threshold level multi-discriminant algorithm are presented, which could enhance the sensitivity and stability of electronic analytical balance; the method of Newton interpolation with LSM(least squares method) combined is applied to improve the nonlinearity of system; and the temperature drift compensation models is established to realize the temperature drift automatic compensation of electronic analytical balance, with the use of regular calibration and zero-tracking technology, the time drift automatic compensation is realized.Finally, according to the measurement of performance requirements and technical specifications of electronic analytical balance, we have completed the experiment test to examine the partial load error, repeatability error and indication error in room temperature.The experimental results show that the above-mentioned design of electronic analytical balance meets the design requirements with scale range of 210g, accuracy of 0.1mg, the maximum allowable error≤0.3mg in room temperature. And it has good stability, high sensitivity and high reliability.