The Research On The Intelligent PID Control Technology Of Electronic Analytical Balance

Electronic analytical balance is a high accuracy mass measuring instrument, which is fast and accurate, simple to operate. It is not only has a good stability but also has a variety of functions such as automatic calibration, fault self-diagnosis, etc. Thus it is widely used in national defense, scientific research, pharmaceutical, chemical and other fields.Electronic analytical balance generally uses the principle of electromagnetic force balance. Electromagnetic force balance sensor and circuit constitute a closed-loop control system. Only when the system is in equilibrium state, it can output stable weighing data. The rapid and stability of closed-loop system balance adjustment is the important guarantee to realize rapid and accurate weighing scales. Traditional balance adjustment is much realized by analog PID (Proportional Integral Derivative) circuit, which is fixed parameters, complicated parameter calibration, long time adjusting and poor adaptability.At the same time, due to the base material, precision manufacturing technology level of domestic constraints, the output consistency of electromagnetic balance sensor is poorer, and a fixed set of PID parameters are difficult to match multiple weighing sensor.Aiming at the PID adjusting technology shortcomings of the existing electronic balance, this thesis design intelligent PID control technology of electronic analytical balance, and mainly includes the following content. The first chapter is introduction, which introduces the research status of electronic analytical balance and PID control technology, summarizes the development and application of existing intelligent PID control technology, and the research significance of this topic is discussed. The second chapter introduces the general structure of electronic analytical balance, in-depth analysis of working principle of pulse width modulation and direct drive type electronic analytical balance, design traditional PID regulating circuit and improved circuit, and make the parameters setting. The third chapter, on the basis of in-depth analysis of composition and working principle of electromagnetic force balance sensor, establish of dynamic model of electronic balance weighing system, get the initial mathematical model initial model of weighing system through the system parameter identification based on the least square method. On this basis, the electronic analytical balance Simulink simulation model is established. The fourth chapter, First of all, according to the mathematical model of electronic analytical balance weighing systems, calculate the PID parameters with the Z-N formula method, the attenuation curve method and the optimal index algorithm make weighing system simulation and contrast adjustment effect. Then, according to the response characteristics of electronic analytical balance and actual debugging rules, combined with the incomplete differential PID algorithm, expert system and variable universe fuzzy control algorithm, design intelligent PID control scheme of electronic analytical balance, and make system simulation. Chapter v design hardware and software of intelligent PID control system of the electronic analytical balance, including precision photoelectric detection circuit, data acquisition circuit, the adaptive fuzzy PID compound control algorithm, etc., which is used for the actual balance system to validate effectiveness of the algorithm through the verification experiment.Simulation and experimental results show that the adaptive fuzzy PID compound adjustment technology can shorten the adjusting time of electronic analytical balance, improve robustness of the system, Stable time balance time is less than 3 seconds, error value of full range is less than plus or minus 0.0003g, repeatability is 0.0005g, achieve rapid and accurate weighing of electronic analytical balance.