Design Of Fuzzy Control System For Piggery Microclimate Environment Based On CFD

With the rapid development of pig industry in China,large piggeries have been widely used.There are some differences in microclimate environment in large piggeries,so it will have a negative influence on the part of pigs' growth.The microclimate of piggery has the characteristics of nonlinear,and traditional fan-wet curtain ventilation system is relatively simple for regulation in piggery microclimate environment,but it has a slow adjustment speed and low control precision.So traditional fan – wet system can't effectively solve problems that caused by pig microclimate differences.In view of the large piggery problems,such as environmental heterogeneity,climate control,nonlinear model of environment information acquisition node limited,a fuzzy control system for Piggery microclimate environment based on CFD(Computational Fluid Dynamics)is proposed.The system combines the microcontroller in piggery with the computer in the monitoring room,using fuzzy control technology and CFD technology,to control the operation of fans and wet curtains,it will make microclimate environment tends to appropriate range for pigs.Farm staff can observe the temperature information of the piggery by 3D graphics form on computer,and view piggery environment in real time.The main work of this paper will be carried out in the following 5 aspects:(1)The piggery microclimate environment fuzzy control scheme is designed.According to the microclimate control of piggery has the characteristics of large time delay and time variation,fuzzy control strategy is selected;Because of the coupling between temperature and humidity control,the decoupling control model is designed;According to the structure of piggery temperature field CFD simulation requirements and piggery,and sensor layout scheme is designed.Due to the distance between piggery and monitoring room is short,but data is large,Ethernet communication was selected.The monitoring room computer can receive the information collected in piggery environment,the temperature field of piggery is simulated by CFD,and is displayed in 3D form.(2)The hardware of fuzzy control system for piggery microclimate environment is designed.The boundary conditions are needed to do the CFD simulation of the temperature field in piggery,therefore,in the middle of the piggery and the wet curtain,one temperature and one humidity acquisition nodes are designed,two humidity acquisition nodes in piggery wet curtain are designed;The switches of the six fans are controlled by the contactor,the speed of two fans are controlled by the frequency converter,the switches of six wet curtains are controlled by an electromagnetic valve.According to the number of data collection nodes and controlled objects,STM32 is selected as the microcontroller.Environmental information are sent to computer in monitoring room by STM32.The monitoring room computer uses this information to simulate the temperature field of the piggery.(3)Fuzzy control system for piggery microclimate environment is simulated.The simulation is divided into the simulation of temperature field and simulation of fuzzy control system for piggery microclimate environment based on MATLAB.In order to verify the accuracy of the simulation of the temperature field,30 points in the simulation of the temperature field is selected,under the same conditions,the actual temperature value in piggery is measured,two methods are compared and analyzed.The fuzzy controller of temperature and humidity is designed,using step response method to simplify and identify control model,and the decoupling controller is designed by using feedforward compensation decoupling method,the control system is built on Simulink and the feasibility of the control method is verified by simulation.(4)The software of fuzzy control system for piggery microclimate environment is designed.Design of temperature and humidity acquisition program,wind speed acquisition program and fuzzy control program on piggery microcontrollers;In order to display the environmental information in piggery in real-time on the monitoring room computer,Design computer monitoring platform of monitoring room,CFD simulation software is secondary developed,to realize the interface between CFD simulation software and detection platform,the CFD simulation results are weighted and sent to the microcontroller as an input of the fuzzy controller.(5)Experiment and result analysis of piggery.In the actual piggery environment,temperature,humidity and wind speed information acquisition are tested,Ethernet transmission functions of piggery and control room are tested,the temperature field simulation function is tested,the overall control effect of control system for piggery microclimate environment is tested.The practical application shows that the system can stabilize the temperature in the piggery at about 21.00?,the absolute error of 0.5?,the humidity can be stabilized at around 65.00%RH,the absolute error of 3.00%RH,the system can meet the feeding requirements.The system has a large improvement in the regulation of microclimate environment in piggery,and reduce the incidence of pigs and manual work.It has a certain practical significance on the development of pig feeding industry.