Study On Fractional Order PID Optimal Control For Precise Injection Of Chemical Reagent

Safety production in the chemical industry has always been a very important issue.With the continuous progress of chemical technology,the requirements for some chemical experiments are also increasing.In the actual production work,the requirements for adding the reaction liquid in the chemical reaction process have become very strict.Once the speed of adding the reactant is too fast or too slow,or the freezing during the feeding process,it will cause insufficient chemical reaction.The situation is extremely easy to cause the production of dangerous gases,or even explosions,and cause safety accidents.In the past chemical reactions,feeding was usually done by people,which did not guarantee the speed and amount of feeding.With the gradual application of micro-syringe pumps to chemical experiments,the safety and the success of the experiment have been further improved.Promote.However,the micro-injection pumps currently on the market are mainly used in the medical field,and there are fewer products in the chemical field.In specific production,the specifications of the container for filling the reactants are not matched,and the speed during the feeding process cannot be well controlled And the filling amount.In response to this problem,this paper introduces fractional-order control into the control of the micro syringe pump.Due to the strong memory of fractional calculus,the modeling of the system is closer to the actual model.At the same time,the fractional-order PID controller is used to further optimize the syringe pump.Control performance.The main work of the paper is as follows:1.According to the research background in the field of chemical experiment safety and the research results of fractional-order control,the micro-injection pump based on fractional-order control is researched and the system is designed.First,the overall design of the system is carried out,and then based on the knowledge of fractional calculus,the controller needed by the system is designed,and then the hardware and software parts of the whole system are designed.2.Use the Riemann-Liouville fractional calculus definition to perform fractional modeling of the micro syringe pump system.Because the electromagnetic energy storage and mechanical energy storage of the stepper motor are related to the fractional order,and the memory of the fractional calculus Strong,the fractional-order model can fully reflect the changes of the system,which provides a premise for the application of the fractional-order controller.3.In the numerical solution of the fractional control system,because the fractional differential operator is an irrational function,it is necessary to discretize it.This paper mainly adopts an improved Oustaloup approximation,which is compared with the previous Oustaloup method.It works better at both ends of the approximate frequency band.Then based on the frequency domain response,a fractional PI~λD~μcontroller is designed.4.When tuning the fractional PID,compared with the integer PID,the fractional PID has two more adjustable parameters,namely the integral orderλand the differential orderλ,so the workload is relatively large when determining the parameters,Here are three tuning algorithms,Particle Swarm Optimization,Beetle Antennae Search and Pattern Search to auto-tune the 5parameters of the controller.And compare their effects.