Analysis Instrument Automatic Sampling System Design

The blood vitamin detector is based on the principle of electrochemical detection.The automatic sample changer is an intelligent and automatic change sample instrument.It can complete the automatic change sample process only by putting the samples to the test position.At present,the existing products of many instrument companies has been high testing technology and inaccurate results,but far from the automation and intelligent direction of the development of testing instruments.The need for manual duty,in the process of measuring the manual sampling,long measuring time,low efficiency.The need for automated transformation of the existing testing instruments,with automatic changing samples instead of manual changing samples.With the implementation of the national "hierarchical diagnosis and treatment system",the analytical instrument is developing towards the direction of intelligence,automation and low cost.The development of automatic changing samples system based on electro-chemical vitamin analyzer has important market value and practical significance.This instrument adopts the system architecture of master slave multi-machine communication.The host computer system uses the ARM embedded system based on Linux as the system core.The main functions are the display of the graphical interface of human-computer interaction,the storage of data collection,the report printing and so on.The lower computer system is divided into changing sample system and measurement system,which completes data sampling and instrument control respectively.The communication between upper and lower computers is RS485 standard protocol.In the motion control module of the lower machine,the movement of the moving pair is a stepping motor.Although it has the advantages of simple control and no cumulative error,the step motor may lose or overshoot when the motor is started or stopped at a high speed.The S curve plus deceleration control algorithm is used in this paper.The purpose is to make step motor classification and deceleration motion,to solve the problem of step motor losing step or overshoot,as well as reducing the flexible impact of the motion mechanism,reducing the loss of the moving parts of the instrument and prolonging the service life of the instrument.In order to realize the constant speed stirring module,the micro motor should be well controlled by PID.The result of the canonical control algorithm is basically thought,and the data is optimized by introducing the two dimensional fuzzy control theory to achieve the on-line tuning of the PID control parameters.With the help of the fuzzy control toolbox provided by MATLAB,the design of fuzzy PID controller is realized.The speed detection of micro motor in the constant speed stirring module is a necessary link of the fuzzy PID speed regulation.The error of the motor speed will directly affect the accuracy of the speed regulation system.Therefore,the T micro motor speed measuring algorithm is used in the constant speed stirring module.According to the algorithm principle,the algorithm is more than the other speed measuring algorithm for the low speed segment.Add precision.In this system,the S curve speed control algorithm,T micro motor speed measurement algorithm and fuzzy PID speed control algorithm are used to ensure the stability of the operation and meet the requirements of the data acquisition precision.