Micro gas chromatography (μGC) system is a miniaturized and portable version of the conventional GC system, suitable for various applications such as healthcare and environmental analysis. The process of gas chromatography requires precise temperature control for the micro-fabricated preconcentrators and separation columns used since temperature changes directly affect retention time. Proportional Integral and Derivative (PID) controllers provide reliable temperature control and can be tuned to obtain the desired response. The conventional method of tuning the PID control parameters by trial and error is a tedious process and time-consuming process.
This thesis aims to develop a PID auto-tuning and control system for auto-tuning microfabricated heaters in modular μGC systems. The developed system is based on the Ziegler Nichols rule-based PID tuning method for closed-loop systems, which uses the relay response of the micro-heater to calculate the PID tuning parameters. The system also includes an analysis system to verify the performance of the PID-tuned values and a tuning system where the PID values can be further tuned to obtain more precise control for the heaters. The aim of developing this system is to reduce the effective tuning time for heaters while satisfying the control requirements. In this thesis, we discuss the tuning methodology and the implementation of the PID tuning and control system, followed by a performance evaluation of the heaters tuned using the proposed system is discussed. / Master of Science / Gas chromatography (GC) is an established technique used for the qualitative and quantitative analysis of compounds present in a mixture. Micro-gas chromatography (μGC) systems are miniaturized versions of conventional GC systems. They are portable, energy-efficient, and facilitate on-site analysis in real-time, which is suitable for applications such as health care, forensics, and environmental analysis, requiring in-field analysis.
GC is based on the principle that components of a gaseous mixture, when passed through a heated column coated with a stationary phase, separate out based on their extent of interaction with the stationary phase. The temperature control needs to be precise since it directly affects the process. PID control is the most common and reliable method for temperature control. It can be tuned to obtain the desired response, which can, however, be a tedious process.
This thesis aims to develop a PID auto-tuning and control system for μ-fabricated heaters in μGC systems. As a part of this thesis, a system facilitating faster tuning of PID parameters for a given heater using the Ziegler Nichols closed-loop tuning method is developed. It uses the relay response of the micro-heater to determine the tuning value. The obtained PID values can be evaluated using the analysis system developed as a part of the system and can be further fine-tuned using the provided system to obtain the desired response. As a part of this thesis, we first discuss the development of the PID tuning and control system, after which the performance of the tuned values is evaluated for two micro-heaters.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/114236 |
| Date | 31 March 2023 |
| Creators | Gupta, Poonam |
| Contributors | Electrical and Computer Engineering, Nazhandali, Leyla, Abbott, Amos L., Agah, Masoud |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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