| In recent years,mudslides,earthquakes and other geological disasters have occurred from time to time,which has brought huge losses to the safety of people's lives and property.If the earthquake can be predicted in advance,the loss can be avoided in time.At present,it is found that the earthquake precursor is closely related to the change of geochemical gas,so the earthquake precursor can be mastered by infrared gas detection technology.Temperature has an important impact on the detection of gas concentration and isotopic abundance.Once the temperature changes,the results of gas detection will be directly affected.Therefore,it is very necessary to develop a high-performance temperature control system.To solve this problem,a high-precision temperature control system using linear auto disturbance rejection algorithm is developed in this paper.Firstly,the research background and significance of the subject are introduced,and the relationship between earthquake precursors and geochemical gases is described.At the same time,this paper summarizes and analyzes the development status of temperature control in gas chamber of gas detection system at home and abroad,and then puts forward the research goal of this subject.Secondly,the selection of temperature control heat source is analyzed combined with thermodynamic knowledge.On this basis,the temperature control scheme is analyzed and demonstrated.The finite element analysis is carried out through COMSOL simulation software to determine the best heating structure of air outlet chamber and complete the design of temperature control box.The simulation analysis shows that the structure can provide a stable temperature environment,which lays a foundation for the realization of high-precision temperature control system.Then,the control model of the system is established,the linear active disturbance rejection control(LADRC)control algorithm is analyzed in detail,and its key parts are simulated to illustrate the advantages of the algorithm.Finally,the simulation temperature control performance comparison between PID and LADRC is completed in Matlab/Simulink.The simulation results show that LADRC algorithm has the advantages of high precision,no overshoot and fast response time.Then,combined with the system temperature control requirements and other factors,the hardware circuit of the temperature control system is realized to complete the functions of temperature acquisition,semiconductor cooler(TEC)drive and system control.Introduce and describe each part of the hardware,such as power supply circuit,temperature acquisition circuit,TEC drive circuit,etc.Then complete the software part of the system,write the programs of the upper computer and the lower computer,the lower computer completes the functions of data acquisition,algorithm operation and data upload,and the upper computer completes the functions of data transmission,display and storage.Finally,the working performance of the air chamber temperature control system developed in this paper is verified by experiments.Temperature control experiment and gas detection experiment were carried out in laboratory environment(ambient temperature 20?)and field environment experiment(ambient temperature 8?).The temperature control target temperature is 30?.The temperature control experiment proves that the temperature fluctuation range of the temperature control system developed in this paper is less than ±0.02? in the laboratory environment and field environment.On this basis,the gas detection experiment is carried out.The experimental results show that the gas chamber temperature control system designed in this paper can provide a high-precision temperature environment for the infrared gas detection system and provide a guarantee for accurate detection. |
PDF Full Text Request