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.

This thesis describes the implementation of zero-cost auto-tuning techniques for embedded Proportional Integral and Derivative (PID) controllers, specifically focusing on their application in the control of proportional valves within Micro Gas Chromatography (uGC) systems. uGC systems are miniaturized versions of conventional GC systems, and require precise temperature, flow and pressure control for the micro-fabricated preconcentrators and micro columns. PID controllers are widely used in process control applications due to their simplicity and effectiveness. The Commercial Off The Shelf (COTS) available controllers are expensive, bulky, need system compatibility and have high lead times. The proposed auto-tuner features simple Python-implemented empirical calculations based on Ziegler Nichols relay-based PID tuning method to determine the optimal PID gains. Leveraging Wi-Fi the system enables tuning for any embedded platform while visualizing transient response through the Graphical User Interface (GUI). The embedded-GUI interface provides a customizable auto-tuning experience extending usage across diverse temperature, pressure and flow regulation applications in environmental analysis. Specifically for uGC systems, the GUI integrates with existing hardware stack using minor software enhancements to enable rapid, automated PID tuning for thermal and flow control applications. The performance is analyzed by evaluating response metrics including overshoot, rise time, and steady-state error. / Master of Science / Commercially available flow and thermal regulators are expensive and bulky. In applications like micro gas chromatography (uGC) systems, these commercial tools to regulate actuator control reduce portability and may require different regulators for different control ranges. To overcome these challenges, we developed an open-source, transparent Proportional-Integral-Derivative (PID) auto-tuner for micro-electromechanical systems (MEMS) actuators in uGC systems. The proposed Python-based Graphical User Interface (GUI) approach leverages simple empirically-driven calculations to determine optimal gains. By interfacing with any embedded system through standard connection like Wi-Fi, the auto-tuner enables interactive, vendor-agnostic tuning while visualizing full transient response. This provides accessible, customizable auto-tuning capabilities to enhance closed-loop PID control across instrumentation and device applications at no or minimal additional hardware cost. In uGC systems, we utilize the same setup for thermal, flow, and pressure control, with additional sensor costs offset by the implementation of multiple closed loops on the same system.Precise temperature and flow control is critical in many applications, such as minimizing fluctuations in analyte retention times in uGC systems. PID control offers reliable closed-loop control for such applications, but tedious manual tuning is required for each system. The proposed auto-tuner presented in this work will greatly simplify PID tuning to improve temperature and flow rate precision in these systems. The performance is analyzed by evaluating response metrics including overshoot, rise time, and steady-state error. This thesis discusses the auto-tuning technique, PID implementation, and experimental performance analysis. Overall, this work presents a novel embedded PID automated methodology for rapid and precise thermal and flow control in uGC and other precision regulation applications. The proposed auto-tuning method provides effective tuning across a wide variety of applications such as motors, temperature and pressure control, and flow regulation systems.