# Fuzzy-PID-Based Atmosphere Packaging Gas Distribution System for Fresh Food
## 3 Results and Discussions
### Gas Distribution System Performance  
The assessment of the performance of the gas distribution system includes evaluating three key metrics: the precision of gas distribution; the stability and dependability of the gas distribution system; and the reliability of data transmission and communication within the system.  
The examination of the gas distribution system is divided into two groups, primarily to evaluate the efficacy of a PID controller in enhancing the precision of gas distribution. The test conditions and indicators of gas distribution include a flow output of 3000 sccm and concentrations of CO\({}_{2}\) at 20%, 30%, and 40%, as well as a flow output of 4000 sccm and concentrations of CO\({}_{2}\) at 50% and 60%. The results indicate that the average error of the gas distribution system without the utilization of a PID algorithm is 2.64%. However, the implementation of a PID algorithm results in an average error of 0.22%, representing a 12-fold improvement in the accuracy of the gas distribution system. Additionally, the utilization of a PID algorithm results in a 50% reduction in gas distribution time, resulting in a significant increase in work efficiency.  
In order to evaluate the stability of the system under varying parameters, a series of gas distribution experiments were conducted using a fuzzy PID control mechanism. Four distinct sets of experiments were performed, each with a different gas concentration index and output flow. The concentration of CO\({}_{2}\) in each set was 30%, 40%, 50%, and 60%, respectively, while the concentration of N\({}_{2}\) was 70%, 60%, 50%, and 40%, respectively. The output flow for each set was fixed at 4000 sccm. The data acquisition cycle for the gas concentration was 1 s, and the data were continuously collected for 300 s, resulting in a total of 1200 data points. The results indicate that the gas concentration remains within a range of 30.0% \(\pm\) 0.3%, 40% \(\pm\) 0.3%, 50.0% \(\pm\) 0.2%, and 60% \(\pm\) 0.2% for each respective set,  
Figure 17: System simulation results.  
thus demonstrating the good stability of the gas distribution system under the fuzzy PID control mechanism.  
The gas distribution remote monitoring system developed in this study employs a 4G DTU as the communication module. The reliability and accuracy of communication transmission, such as packet loss rate and accuracy rate, were evaluated and calibrated before deployment. The system was tested under the conditions of a communication distance of 1200m, a communication time of 20 min, a temperature range of 23-33 degrees Celsius, and a humidity range of 35-45%. The packet loss rate and accuracy rate of the system under the RS485 interface were found to be satisfactory, with no garbled characters and no packet loss. Furthermore, when the system was subjected to continuous transmission for 110 h, with a baud rate of 115,200, number of bytes sent of 1000, and transmission interval of 1000 microseconds, the packet loss rate of data transmission was found to be between 0.74 and 0.77%. These results demonstrate that the reliability of the system's data transmission and communication can be fully guaranteed. The results show that by setting the data collection interval at seconds on the cloud server, the data transmission delay is approximately 15 ms, and the gas distribution system is able to accurately complete remote real-time monitoring with stable, normal, and accurate communication.