The Design Of The Speed Measurement And Control Software For The Molecular Pump Of Virtual Instrument

The superiority of the pumping speed of molecular pump performance for molecular pump basic theory has great significance,for the subsequent research and development,performance improvement as well as to the integrity of the vacuum system design methods are very important to improve the condition,more important is rapid,accurate,effectively to molecular pump pumping speed performance testing has become an important development goal of vacuum pump industry.At present,there are still some problems in the process of pumping speed test of molecular pump in China,such as low degree of automation,difficult to adjust the vacuum test point,and late data collection,which are difficult to meet the test needs of enterprises.Therefore,aiming at the pumping speed test of the molecular pump,the platform develops a set of automatic test software of the upper computer,so as to achieve the purpose of data collection and automation of vacuum degree control,which has practical significance.Firstly,the paper systematically introduces the test principle,test flow and test platform structure of pumping speed of molecular pump.Due to molecular pump in the process of pumping speed test need for vacuum degree adjustment and control,this is in order to make the test can effectively in different vacuum conditions,and compared with the other controller,PID controller has the characteristics of simple structure,and in practice,especially in industrial production is easy to implement,at the same time also can maintain strong superiority,therefore widely used in all kinds of industry control.In this paper,the PID algorithm is proposed as the main algorithm for vacuum control in the process of pumping speed test.Secondly,the data of initial parameters of PID algorithm is analyzed and discussed.Of PID controller can be used in practical process to obtain a good control effect,the result depends on whether the PID controller parameter selection of outstanding,for a new control system,the system of the initial PID parameters is often difficult to determine,on the other hand due to the traditional artificial experience setting method require staff have higher skills,able to operate too complex problems,but even the experienced operators also need to spend a lot of time and energy on the scene debugging,it is obviously for the high efficiency of be particular about laboratory test.Therefore,a quick and simple method is needed to integrate the initial values of PID parameters.In this paper,a relaying PID parameter integration method is used to modify the initial value of PID parameter offline.Then,the parameters of the PID algorithm are tracked and analyzed,and the tuning method is analyzed and studied.Although the relay type integration method is simple and easy to use,but used in the pumping speed of molecular pump in the process of the actual test,found that the vacuum degree adjustment process is a process of dynamic balance,this shows that the test environment and the status of test device does not always remain the same,the result of the use of the above type relay this way of setting PID parameters can be offline,it will effectively control the vacuum degree,its control performance will with the change of the pumping speed test system state.Therefore,in order to maximize the control effect of vacuum degree,the PID controller has a certain adaptive ability to the pumping system,which requires certain requirements on PID parameters and can be dynamically adjusted.Fuzzy PID controller is a combination of classical PID and fuzzy control,so that PID parameters have the ability to adjust online.Finally,the development tool of the upper computer software in this paper is LabVIEW,which aims to complete the software development work of the communication part of the test device,data processing part,algorithm control part,parameter setting part and human-machine interface part.And the upper computer software can be used to carry out the actual test of the pumping speed of the molecular pump,through the analysis and discussion of the experimental results,so that the upper computer software can achieve the molecular pump in the pumping speed test process of data acquisition,PID parameter setting,vacuum control and other functions.The experimental results improve the test accuracy and test efficiency,and have some practical significance and reference value for the speed test of molecular pump.