Design And Experiment Of Online Detection Of Water Content Of Fresh Tea Leaves And Online Control System Of Fixation

In the process of fresh tea leaves fixation,the water content plays a crucial role in the adjustment of the killing process parameters.There are many means to detect the water content of fresh tea leaves,but in the actual production of fresh tea leaves water content detection work exists in the detection efficiency is not high,the detection accuracy is not accurate and does not combine the detection results with processing parameters and other problems.In response to the above proposed problems,this thesis designs an online control system for online detection and fixation of fresh tea leaves water content based on near-infrared spectroscopy technology.The system is designed to quickly and accurately detect the water content of fresh tea leaves after picking,and then regulate the fixation temperature and duration based on the detection results.The main research of this thesis is as follows:(1)Determination of water content of fresh tea leaves with spectral data acquisition.Collect fresh tea leaves of the same species and different batches.After determining the water content determination method and the spectral data collection method,the collected fresh tea leaves were numbered and then their spectral data were collected in turn and their water content was determined.(2)Pre-processing of spectral data of fresh tea leaves with modeling of water content detection.The collected spectral data were pre-processed with multiple scatter correction and standard normal variety,and a water content detection model was established using partial least squares.Model performance evaluation indexes are introduced to analyze and compare the detection models built up from original spectral data with those built up from spectral data processed by different pre-processing methods.(3)Build the platform of water content online detection system and design the control system of fixation machine.After designing the structure of the online water content detection platform by NX.drawing software,we purchased the corresponding hardware equipment and completed the construction of the whole platform.After that,we designed the control system of the fixation machine,drew the relevant electrical drawings and completed the construction of the electrical cabinet.(4)Software design of on-line water content detection system and control system of fixation machine.After the hardware part is completed,the online detection interface is designed on the basis of Lab VIEW,and the communication between each component is realized on this basis.The inverter and PID temperature control algorithm are then used to regulate the rotational speed of the fixation drum and the temperature inside the fixation drum in the control system of the fixation machine.(5)Fresh tea leaves water content detection model test and fixation test.Static tests of the water content detection model were conducted first,followed by dynamic tests.The consistency of the dynamic test results with the static test results shows that the system can be applied to actual production.Finally,the fresh tea leaves fixation test was designed to find the most matching fixation process parameters with fresh tea leaves of different water content intervals.This study provides a new idea to realize the online detection of fresh tea leaves water content and the real-time regulation of the fixation process.