Drift Mechanism And Its Compensation Research Of Electronic Analytical Balance

The development of weighing instruments, especially electronic weighing instruments, has become an important symbol to measure the level of nationa l science and technology and industrial development. Electronic analytical balance is the integration of sensors, analog electronics and microprocessor technology, with multiple functions of automatic calibration, automatic display, tare, automatic output of data, automatic fault detection and overload protection. It is a standard equipment of widely used in laboratories, medicine, defense and so on.Due to poor foundation of material and heat treatment process, low machining accuracy, backward assembly technology, lack of theoretical basis of electromagnetic force balance sensors, short of development and application of information processing and compensation methods, there is a gap between Chinese manufacturers of electronic analytical balance and the inte rnational advanced level. To catch up with international advanced level still need to overcome technical difficulties, especially the drift mechanism analysis with complex hardware compensation methods, etc. These factors are not conducive to the improveme nt of electronic analytical balance's performance.Aiming at the large amount of drift and poor stability caused by temperature and time, this thesis consists of five parts: Chapter 1 is an introduction of advanced technology about electronic analytical balance at home and abroad and achieved technical index. The principle of PWM electronic analytical balance is elaborated and the background and significance of this research explained; Chapter 2 introduces the concept of temperature drift of electronic anal ytical balance, and analyzes temperature characteristics of permanent magnet, movable coil length, voltage reference sampling resistor and mechanical structure, and finally focuses on the electronic analytical balance's magnetic structure temperature field simulation and results analysis based on ANSYS; Chapter 3 mainly research the time drift mechanism of electronic analytical balance, including time stability analysis of a permanent magnet, the creep analysis of mechanical structures, drift analysis of el ectronic components and acceleration of gravity; Chapter 4 describes the hardware compensation method of electronic analytical balance temperature drift, a temperature drift compensation model based on multi-sensor weighted fusion and time drift compensation based on zero-tracking technology are established, including derivation, final compensation model and program flowcharts; Chapter 5 proposes detailed experiment process of drift compensation and zero tracking, and compare the temperature characteristics and time characteristics of electronic analytical balance before and after drift compensation, and ultimately achieve the technical specifications of electronic analytical balance.The proposed methods in this thesis were used on an electronic analytical balance with a range of 220 g and resolution of 0.1 milligram, and test results show that the indication error is less than the indication error for the 1st class balance specified by Chinese National Standard, “GB/T26497-2011 Electronic balance”, form 10? to 30?. What's more, the algorithms are easy to implement, with excellence real-time and low cost. The products have initially reached the international advanced level.