The Research On Controlling System Of600-Seed Automatic Iochemical Analyzer

Automatic biochemical analyzer is a large-scale testing apparatus whichcollects light, electricity, machines and liquid in itself. It is mainly used to test thebiochemical indicators of human body fluids and is one of the essential equipment formedical clinical examination. The research of biochemical analyzer in china startedlate and the level is low, so the precision gaps between the domestic instruments andthe world advanced equipments are relatively large. Although controlling system isthe core of the biochemical analyzer, the improvement of its stability is a long way togo. This paper aims to research and develop a medium-sized automatic biochemicalanalyzer control system which has a fully function, stable performance, reliableeconomic, simple to use, and it can also provide practical guidance for the follow-upproducts development.This paper first introduces the technology development status and trends ofdomestic and foreign biochemical analyzer and describes the types of biochemicalanalyzer, so introduce the focus of this article—discreted automatic biochemicalanalyzer. Then introduces the working principle and the overall structure of thebiochemical analyzer, highlights the designing of the control system design: thehardware part and software part. From the hardware point of view, the input andoutput amonnts of the entire control system is very many, so the system has very stricttiming and highly real-time. Therefore, we select the high-performance ARMchip—SAM3U4E(the Cortex-M3core) and Altera chip EP4CE10F17C8N. They formthe core of the hardware control system together. This not only simplifies thehardware structure, but also improves the stability and reliability of the entirehardware system. The software system includes PC software and controlling software.In the control software of the next-bit machine, we use FPGA to implement thereal-time control of the system. This can weaken the role of the host controller (MCU)in real-time control process, enhance the stability and reliability of the main program.The biochemical analyzers belong to Optical analytical instruments, thespectrophotometric method is established based on the material selectivity of the lightabsorption principle. So the accuracy of the collecting optical signal data acquisitionsystem is required very high. In order to facilitate the adjustment of the signalstrength of the data acquisition system, we use digital potentiometer and13-bits high-speed A/D converter chip AD7327.Both to meet the accuracy requirements, butalso reduces the cost of the system.The main control objects of automatic biochemical analyzer are stepper motors,the controlling way of stepper motor controlling has two ways: constant voltage andconstant current. Since the constant voltage control mode of the stepper motor has thehigh requirements, motors current wave is square wave, the torque is not constant,there is a relatively large pulse in the process of motor running, so in this paper, weselect the constant current controlling mode. We choose a different driver chipsdepending on the stepper motors, meanwhile we take a different trapezoidalacceleration and deceleration curves to ensure the smooth operation of the motor.Finally, some test experiments to validate the stability and reliability of theentire control system. Experimental results show that the performance of the controlsystem is fully able to meet the instrument design requirements.