Mechatronics Systems Engineering - Theses, Dissertations, and other Required Graduate Degree Essays

Receive updates for this collection

Modeling and Control of the Fuel Supply System in a Polymer Electrolyte Membrane Fuel Cell

Date created: 
2017-05-30
Abstract: 

Prolonging membrane longevity as well as improving fuel economy are essential steps toward utilization of fuel cells in industrial applications. Focusing on polymer electrolyte membrane (PEM) fuel cells, the present work elucidates a systematic approach to deal with cell durability issues, inflicted by membrane pinholes. This includes the model-based control of fuel overpressure, which is defined as the pressure difference between the anode and cathode compartments, at the inlet side of the fuel cell stack. Moreover, to enhance fuel savings, this work proposes a novel model-based technique for estimation of hydrogen concentration, which is used as the basis of fuel purging control. Employing a Ballard 3kW test station equipped with a 9-cell Mk1100 PEM fuel cell, the entire system is modeled using pneumatic variables. The developed model is experimentally validated. Depending on the underlying objective, a relevant system configuration for the PEM fuel cell anode is adopted. These include a flow-through anode, dead-ended anode, and anode with recirculation structures. A model predictive controller (MPC) is deployed to achieve the controller objectives, which include the improvement in control of the system transient response during the load change, reduction of hydrogen emission, and retaining the cell voltage level of a defective cell, by maintaining the fuel overpressure in the desired region. Furthermore, the controller performance is verified experimentally. Using the pressure drop across the fuel cell stack anode, the hydrogen concentration on the anode side is estimated in a hydrogen-nitrogen gas mixture. This pressure drop is correlated to the dynamic viscosity of a gas mixture. The estimation model which is verified experimentally for various scenarios provides a reliable and cost-effective method that can eliminate the use of the hydrogen sensor. This model is then utilized as the basis for controlling the fuel purging. Deploying an MPC based multivariable control strategy, both fuel overpressure and hydrogen concentration are controlled.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Farid Golnaraghi
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

A Fully 3D-printed Integrated Electrochemical Sensor System

Author: 
Date created: 
2017-08-30
Abstract: 

This thesis investigates the design, fabrication, and characterization of a 3D printed electrochemical sensor as well as compact potentiostat circuits on Printed Circuit Board (PCB) for portable electrochemical sensing applications. Conductive 3D printing technologies are investigated as well as the advances in sensors and electronics applications. An optimized Directly Ink Writing (DIW) technique is adapted to a novel 3D-PCB fabrication platform using silver nanoparticle ink for electronics applications. An electrochemical device called potentiostat is designed based on an open source system. Its prototype is 3D printed on FR4 substrate. Using the same 3D platform, a lactate sensor which is composed of a 3-electrode is printed on the flexible substrate. Together, the 3D printed system demonstrates the electrochemistry test including cyclic voltammetry (CV) and amperometry. Results of this research demonstrate that 3D-PCB technology can significantly accelerate the fabrication process of conventional electronic, and merge its capability into electrochemical applications.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Woo Soo Kim
Jiacheng Wang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Integrated sensing from multiple wearable devices for activity recognition and dead reckoning

Date created: 
2016-03-09
Abstract: 

Wearable devices are increasingly prevalent in our everyday lives. This thesis examines the potential of combining multiple wearable devices worn on different body locations for fitness activity recognition and inertial dead-reckoning. First, a novel method is presented to classify fitness activities using head-worn sensors, with comparisons to other common worn locations on the body. Using multiclass Support Vector Machine (SVM) on head-worn sensors, high degree of accuracy was obtained for classifying standing, walking, running, ascending/descending stairs and cycling. Next, a complete inertial dead-reckoning system for walking and running using smartwatch and smartglasses is proposed. Head-turn motion can derail the position propagation on a head-worn dead-reckoning system. Using the relative angle rate-of-change between arm swing direction and head yaw, head-turn motion can be detected. The experimental results show that using the proposed head-turn detection algorithm, head-worn dead-reckoning performance can be greatly improved.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Edward Park
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Wearable sensor system for human localization and motion capture

Date created: 
2017-04-27
Abstract: 

Recent advances in MEMS wearable inertial/magnetic sensors and mobile computing have fostered a dramatic growth of interest for ambulatory human motion capture (MoCap). Compared to traditional optical MoCap systems such as the optical systems, inertial (i.e. accelerometer and gyroscope) and magnetic sensors do not require external fixtures such as cameras. Hence, they do not have in-the-lab measurement limitations and thus are ideal for ambulatory applications. However, due to the manufacturing process of MEMS sensors, existing wearable MoCap systems suffer from drift error and accuracy degradation over time caused by time-varying bias. The goal of this research is to develop algorithms based on multi-sensor fusion and machine learning techniques for precise tracking of human motion and location using wearable inertial sensors integrated with absolute localization technologies. The main focus of this research is on true ambulatory applications in active sports (e.g., skiing) and entertainment (e.g., gaming and filmmaking), and health-status monitoring. For active sports and entertainment applications, a novel sensor fusion algorithm is developed to fuse inertial data with magnetic field information and provide drift-free estimation of human body segment orientation. This concept is further extended to provide ubiquitous indoor/outdoor localization by fusing wearable inertial/magnetic sensors with global navigation satellite system (GNSS), barometric pressure sensor and ultra-wideband (UWB) localization technology. For health applications, this research is focused on longitudinal tracking of walking speed as a fundamental indicator of human well-being. A regression model is developed to map inertial information from a single waist or ankle-worn sensor to walking speed. This approach is further developed to estimate walking speed using a wrist-worn device (e.g., a smartwatch) by extracting the arm swing motion intensity and frequency by combining sensor fusion and principal component analysis.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Edward Park
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Design of a hybrid spherical manipulator for lower limb exoskeleton applications

Author: 
Date created: 
2017-03-06
Abstract: 

An estimated (7.1%) of North American residents suffered from an ambulatory disability and mobility disablements in 2013. These disabilities cost an estimated annual equivalent of $375 billion in family caregiver support. One emergent technology that aims to address this health problem and improve the quality of life for sufferers is a lower-body exoskeleton which is a wearable robotic system that completely or partially supports users weight and provide controlled guidance of legs movements, thereby allowing them to stand and walk. One major shortcoming of current exoskeleton technologies is their limited range of motion about the hip joint. Such joints are capable of three rotational degrees of-freedom (DOFs). Current technologies only provide a single DOF hip-centered movements. The other two DOFs are either fully constrained or only available with passive motion. This design scheme generally results in a serial joint structure within the exoskeleton device, which has an inherently lower payload to-weight ratio than a parallel structure counterpart. Therefore, this characteristic leads to bulkier than necessary devices. The objective of this thesis is studying the feasibility and later on design compact three DOF robotic joints to replace the single DOF of the hip actuator of the commercially available exoskeletons. In this thesis a three degree-of-freedom (DOF) hip exoskeleton system that is capable of providing decoupled or combined 3-DOF rotational motion to a separate and passive target joint (i.e. the hip joint) is proposed.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Siamak Arzanpour
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Investigation of mesoscopic degradation phenomena in fuel cells

Date created: 
2017-03-16
Abstract: 

Commercialization of fuel cell technology for heavy-duty bus application relies on the durability of the components used in fuel cell stack. The durability of polymer electrolyte fuel cell (PEFC) is affected mainly by degradation of catalyst coated membrane (CCM). CCM consist of Pt/C based catalyst layers coated on both sides of PFSA ionomer membrane. In an operating fuel cell, PFSA ionomer membrane degrades under the action of combined chemical/mechanical stresses and Pt/C electrocatalyst degrades due to high voltage excursions. In this thesis, the most relevant approach to understand PEFC degradation during its operation is carried out by employing in situ stressors. The mesoscale morphology and affected physico-chemical properties of fuel cells are investigated with the commonly encountered stressors. Firstly, the mesoscale morphology and its relation to physico-chemical properties of the ionomer membrane under the influence of an accelerated stress test (AST) featuring in situ coupled chemical/mechanical stresses are investigated. The role of combined chemical/mechanical stresses on the ionomer membrane mesoscale morphology and structure is studied using transmission electron microscope (TEM) and thermogravimetric analysis. It is determined that the microstructure of PFSA ionomer membrane is strongly influenced by the degradation history of PEFC. The mesoscale morphological degradation is found to precisely influence the water uptake of the ionomer membrane. The effects realized through chemical and mechanical stressors in coupled and decoupled forms are evaluated through the mesoscale morphology and physico-chemical property studies. Secondly, cathode catalyst layer (CCL) subjected to a voltage cycling AST to mimic the high voltage excursions is studied. It is found that the CCL degradation led to the inhomogeneous distribution of solid and pore phases. The change in the CCL structure accompanied by the platinum agglomeration, carbon corrosion and spatial redistribution of ionomer with voltage cycling is investigated using TEM micrographs with phase sensitive mapping. The observed degradation effects of CCL through the agglomerated and dissolved platinum, corroded carbon, spatially redistributed ionomer, and compacted solids revealed the underlying mechanisms of activation and mass transport losses. Overall, a fundamental understanding of degradation mechanisms in CCM components at mesoscale is achieved from in situ fuel cell testing, which is of particular interest in commercializing and developing durable fuel cells.

Document type: 
Thesis
File(s): 
3-D reconstructed structure of pristine PFSA membrane
3-D reconstructed structure of degraded PFSA membrane
Senior supervisor: 
Erik Kjeang
Steven Holdcroft
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Totem-pole power factor correction rectifier with Gallium-Nitride devices for telecom power supply

Date created: 
2016-12-14
Abstract: 

Wide-bandgap (WBG) semiconductor technology will largely replace silicon switching devices in the active power factor correction (PFC) circuit of a telecom power supply in the near future. Superior electrical characteristics of commercially available Gallium Nitride (GaN) devices make totem-pole PFC a clear winner over competing topologies in terms of efficiency. This thesis focuses on the development of a totem-pole PFC using state-of-the-art GaN devices for next-generation telecom power supplies. A detailed investigation of ac zero-crossings of this topology has successfully identified the rapid fluctuation in voltage across low-frequency MOSFET as the source of common-mode noise. An equivalent circuit accompanied by a set of equations correlate different circuit parameters with the noise generation. Challenges associated with current reversal near zero-crossings of a synchronous totem-pole PFC are studied and a formerly unreported source of common-mode noise generation around ac zero-crossings has been investigated in detail.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jiacheng (Jason) Wang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Functional magnetic resonance imaging in white matter using 3 T gradient-echo-planar imaging

Date created: 
2016-12-14
Abstract: 

White matter structures make up functional connectivity of the brain. The ability to observe white matter in action will provide insight into both normal brain function, as well as diseases characterized by loss of white matter integrity. Detection of functional magnetic resonance imaging (fMRI) activation in white matter is has been increasingly reported despite historically being controversial. The majority of development work to-date has used high-field MRI and specialized pulse sequences. In the current study, we utilized 3T MRI and a commonly applied gradient echo (GRE) echo-planar imaging (EPI) sequence to probe the robustness of fMRI activation using conventional clinical conditions. Functional activity was stimulated in target regions of interest within the corpus callosum, using an established visual-motor interhemispheric transfer task. The results confirmed that it was possible to detect white matter fMRI activation at the group level (N = 13, healthy individuals). Individual analyses revealed that 8 of the 13 individuals showed white matter activation in the body of the corpus callosum. Overall, the group results replicated prior 4 T MRI studies, but showed a lower percentage of individuals with activation. The findings support the concept that while white matter activation is detectable, the activation levels are close to thresholds used for routine 3 T MRI studies. Furthermore, by applying alternate hemodynamic response functions during analysis, larger clusters of activation were seen at the group-level

Document type: 
Thesis
File(s): 
Senior supervisor: 
Carolyn Sparrey
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

3D Failure Analysis of Fuel Cell Electrodes using Multi-Length Scale X-ray Computed Tomography

Author: 
Date created: 
2016-09-06
Abstract: 

X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Similar to medical CT scanners, laboratory XCT enables low-intensity X-ray imaging of a specimen at different incident angles followed by reconstruction into three-dimensional views. Fuel cell materials are compatible with this technique as they are sufficiently transparent to X-rays. In this thesis, electrode failures are analyzed by comparative tomography data sets for conditioned beginning of test (BOT) and degraded end of test (EOT) membrane electrode assemblies subjected to cathode degradation. Cracks and thickness of the cathode catalyst layer (CCL) are analyzed at the micro length scale, followed by a complementary nano length scale analysis of the fine porous structure. Additionally, a novel image processing based technique is developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels in the degraded CCL. The results of this work reveal several failure modes of catalyst layers including but not limited to carbon corrosion, Pt agglomeration, and Pt migration. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Erik Kjeang
Woo Soo Kim
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Waste heat-driven adsorption cooling systems for vehicle air conditioning applications

Date created: 
2015-10-01
Abstract: 

Waste heat-driven adsorption cooling systems (ACS) are potential replacements for vapor compression refrigeration cycles in vehicle air conditioning (A/C) applications. Working pairs in an ACS are a combination of an adsorbent material (e.g., zeolite and silica gel), and an adsorbate (e.g., water and methanol). Most of these materials are non-toxic, non-corrosive, non-ozone depleting, and inexpensive. Besides, an ACS operates quietly and valves are its only moving parts. However, the bulkiness and heavy weight of ACS are major challenges facing commercialization of these environmentally friendly systems.The focus of this research is to develop a proof-of-concept ACS with high specific cooling power for vehicle A/C applications. As such, this Ph.D. dissertation is divided into three main parts: (i) adsorbent material characterization, (ii) adsorber bed design, and (iii) ACS design. In-depth analytical and thermodynamic cycle models are developed to understand the phenomena in adsorption process, adsorber bed and ACS. Also, a modular two-adsorber bed ACS equipped with thermocouples, pressure transducers and flow meters is designed and built for the first time at the Laboratory for Alternative Energy Conversion (LAEC) to test different adsorbent materials, adsorber beds, condensers, and evaporators under different operating conditions. A low-operating pressure evaporator with capillary-assisted tubes is designed and installed on the testbed to improve the performance of ACS. In addition, a novel expansion valve and control valves are proposed to simplify the control system and reduce the complexity of ACS for vehicle A/C applications. Using this ACS testbed with enhanced performance, a specific cooling power of 150 W/kg of dry adsorbent is achieved.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Dissertation) Ph.D.